thank you for the constant content Steve. the SML build project was spectacular! We all appreciate you taking the time to document the build processes for us. Spreading the knowledge among the wrench bending community is awesome. Keep up the good work
Great explanation and one I have not heard anyone else offer. So many people talk about waste gates as if we are all experts already. Thanks for taking the time to explain the principles of operation.
Actually with no boost reference it regulates the exhaust turbine inlet pressure only so it is regulating the drive pressure to 10psi. How much boost it will make then is subject to the turbo and engine setup. I have seen twin turbo BBC make 20psi of boost with only 8psi of drive so the wastegate would be like having nothing at all. Now put a 66mm single on and you would probably only see 8psi of boost and like 25psi of drive then the gate would be opening to keep from sending the little single into parts scatter never never land. What you say about needing to control pressures on both sides to prevent an overboost situation or a turbo destruction situation is VERY true.
It depends on the ratio between the wastegate and diaphragm area. A little simplified. If the ratio is 2:1, the wastegate is adjusted to 10 psi with the boost reference connected and you have a drive pressure of 10 psi then the drive pressure would theoretically need to be 2*10+10=30 psi to open the wastegate without the boost reference.
This is probably one of my favorite “Steve Tech” vids so far. I’ve always wondered if folks use waste gates (or anything else to help control boost) on centrifugal superchargers. Thanks Steve, man I love this channel!!
I believe the item you're looking for is a blow off valve, or bleed valve in some circles. Bleeding air after you've used mechanical energy to compress it, makes no sense on a mechanically driven air pump, unless it's momentary to avoid surge, when the throttle shuts.
As a mechanic from Australia. Thank you for explaining that. I have had many an argument with apprentices and that explains it really well. Great content.
Steve old truck driver here. My turbo had a waste gate operated by a rod and hose to the turbo. Was told when the turbo reached a certain psi the gate would open and bypass exhaust psi.
That’s correct, the boost pressure is set by a spring only on most diesel trucks. When boost pressure is greater than the spring pressure the wastegate opens and maintains the max boost pressure
Boost reference on the wastegate also prevents overcharging the charge pipes when the motor goes from full throttle and high boost to no throttle (return to idle)...this momentarily spikes boost pressure when all that air has no place to go - but that spike boost also fully opens the wastegate releasing the exhaust pressure on the hot “drive” side of the turbo while the now unbalanced spike on the charge side acts as a “brake” on the cold side, which is at that moment only driven by the turbo impeller momentum. When you control boost only on the manifold reference side of the wastegate, you do so with an (air) pressure regulator which eliminates the closed throttle “spike” action on the wastegate (eliminated by the high pressure regulator) so you have to also run a cold side (manifold reference) blow off valve to release the excess pressure (and make that signature rice-rocket hiss sound on deceleration)...
Thanks Steve! I have an understanding now, with the new stuff the wastegates are electronically controlled so I’m used to seeing the information based off of voltage. I appreciate these videos they are great for engine theory
I always wanted a variable vane pitch viscous clutch [vaguely like a torque converter] on a supercharger so it could have variable boost with a single fixed ratio pulley arrangement where the boost load [resistance created by natural back pressure] working against the variable pitch vanes of the clutch would set the final boost, and then simply change the vane pitch upward from a lower level to increase boost as the engine needs it. Also, such a system would be capable of a total [or near total] shut-down in case of emergencies. In other words, kinda like the fuel cutoff mechanism on a diesel engine [or any engine for that matter] there would be an emergency shut-down mechanism on the viscous coupling that allowed you to completely disconnect it from driving the blower in case of an engine runaway or a crash.
I think you should make a smx 6 cylinder for us lower grade guys.you can call it the smaxx-6 keeping it around 1600 HP.would sell many.great job on all your projects.pull 2 cylinders off the smx and will be perfect moduler,all same parts.thanks for all the great info.
WW2 fighters before dual stage and dual speed super chargers used to have to be throttled at low altitude to not over boost very cool setups they had back in the day.
A shop vac with your hand over the end.... it spins faster because it does not have to work as hard, no load , its pushing no air... LESS drag with your hand over the end of the hose. It's counter intuitive , but makes sense if you think about it.
When you first started your business, did you ever think engines would make the power they do now? What's the biggest improvement in the last 15 years?
Steve is intelligent....From a physics side any science fans out there, look how forward facing, reverse facing and flat blade impellers work for any type of centrifugal blowers. Opening flow can add more CFM and increases the load on an whatever is driving it. I've seen electric motors burn up because a blower hose with x amounts of restriction popped off.
Makes sense. It's a limiter. Like a compressor for audio, Or a check valve on a water line. Few other thing I can think of. But my fingers are tired. Good viddy Steve.
Just remember, every engine feels the fastest right before it blows up. If its too good to be true, it probably is. Infinite boost is only fun for a few seconds lol..
When controlling boost only through the bottom port you dont restrict the pressure to the bottom port that will cause an initial boost spike then pressure will return to normal the correct way to do it is create an air leak to the bottom port to bleed off pressure
His explanation was perfect even for a person with minimal automotive knowledge, If you could not understand his explanation then this channel is way above your pay grade! Also you do realize that turbos, Superchargers and waste gates are all part of his day job!
Makes me so curious because the centrifugal supercharger kit I've been looking into has a blow off valve and a wastegate. I have some questions to ask now, as always thank you for the Steve tech tips they're invaluable to people like myself that just like to wrench every day. J Swap Jason.
Some of them have recirculating air, so instead of compressing and releasing air, it just shoots the air back into the intake instead of atmosphere. Yours may not be quite the same, but that way it keeps air flowing, but under pressure, so things don't go boom.
I think wastegates are typically only found with turbochargers, as the waste gates takes the "waste" or excess exhaust gasses and vents this extra exhaust gasses either into the atmosphere A.K.A: the screamer pipe. The blow off is typically on the intake/cold side/boost/compressor piping leading to the throttle body. When the throttle blade is open, the blow off is sealed allowing all the compressed and/or intercooled air into the engine. When the engine throttle is closed, a vacuum/boost/throttle position sensor tells either the computer or just via vacuum signal to open this vent to prevent the compressed air from back feeding the compressor side of the turbos. When the boost gets trapped between the compressor side and a closed throttle, the pressure works against the engines exhaust driven side to attempt to slow the compressor wheel down. This forced slowing of the compressor while the exhaust is still trying to drive the turbo the other direction ends up causing broken impellers and broken turbos. Superchargers and prochargers are driven by the engine by mechanical connection, like a belt or crankshaft driven setup. Backfeeding this style boost set up, when it doesn't grenade the supercharger, tends to excessively wear the supercharger. Im fairly sure the prochargers will use a blow off only to remove excess cold side/intake side boost. Blow offs only releive the stored boost on the intake side. Waste gates are on the exhaust side(turbos only) and vent some portion of exhaust to maintain a boost pressure setting. Supercharger\prochargers change boost pressure by changing the pulleys used om the blower and crankshaft. A small pulley on the charger and big (either tooth count or specifically sized diameter) then the blower is considered overdriven. Driven faster tham engine RPM by whatever chosen amount. Swap those same pulleys around and the blower makes less boost and is then under driven. Driven slower than the engine RPM. Prochargers can be a bit different, as I think some rowdy race ones can have their drive ratios and/or pulleys changed to affect the boost curve(somewhat) and also the total boost created. Turbos need the exhaust side gate otherwise the boost gets trapped and tries spinning the turbo different directions at the same time. Also, venting the exhaust gas, as this is what drives the compressor side of a turbo is slowing the turbo down or controlling boost in the most accurate/safe/efficient way. Assuming the waste gate is the correct size to vent enough exhaust fast enough to keep turbo RPM and thus turbo boost at a stable spring regulated pressure or a CO2 regulated pressure. There's tons more of the nitty grtitty tech, and I am aware Steve has gone over everything in this comment in this video. As such, there are newcomers to car modifying getting interested every day. Cmon down, you might be the next person supercharging a 1UZ for drifting down unda'. Or maybe the next person to revolutionize turbo/charger/boost control tech. Bring out ya hot rodders....
@@threadtapwhisperer5136 gerzybear look it up for a J series. Tell me what you think. I understand how everything works I'm just curious after Steve's video.
If your car is equipped with a mass air meter you must use a bypass valve and not a blow off valve, If you install a blow off valve on a mass air car it will effect how the engine runs!
@@NeverEnoughPyro40 fair enough. But FuelTech ft600 will be controlling the car. So that isn't an issue. Fuel tech uses absolutely density I believe. I'm just curious how this will Affect my particular set up I plan on using.
I have to disagree on multiple points when you were talking about speeds relative to shop vac, blower and turbo shaft. 1: When you restrict the intake or exhaust of a shop vac the motor slows down because it is under more load. This is due to the increased mechanical resistance, the speed of any electric motor assembly is determined by the mechanical and electrical resistance of the system as a whole. You can see this first hand by restricting a computer's fan and monitoring it's rpm with an app such as Speedfan. 2: Opening a blow off valve will not overspeed the turbo. Turbine speed it determined by the volume of exhaust flow which is a product of intake volume. If you lose intake flow you will also lose exhaust to drive the turbine and it will slow down. 3: On a SC setup if the gate is vented to the atmosphere the difference in airflow through the compressor will be what ever the difference in efficiency is at the given boost pressures and compressor speed. Here is an example using nice round hypothetical numbers. Engine NA consumes 1000 cfm @ 7k rpm, SC is geared to supply 2000 cfm with an engine speed of 7k that will equate to 14.7 psi of boost. Now lets assume that a drop in boost pressure of 1.5 psi (10%) causes the compressor output to go up proportionally to 2200 cfm that just means the gate needs to vent 400 cfm so the engine sees a drop of 10% (1.5 psi). I've seen some recirculate the gate back to the intake side of the SC and that can cause issues but I've never seen a problem when vented to the atmosphere. These were street applications that weren't anywhere near the bleeding edge but I can't see it being a problem either way when vented to the atmosphere since the compressor is under less load at lower boost levels.
I have to disagree with your points 1: I'm not sure you have tried restricting a shop vac. The motor speed definitely increases. When you block the flow path of a shop vac the air in the impeller is basically trapped and spins with the impeller as it can't go anywhere else. This is less load on the motor as it is only spinning that air and not moving it anywhere. 2: Steve is talking about a blow off valve on the intake side of the engine instead of the exhaust side. If the engine reaches the desired boost level and then the intake is vented it is making enough exhaust gas for that boost level. If the engine increases rpm / load at this point then more of the intake will need to be vented to hold stable boost but there will be more exhaust flowing through the turbo so it's speed will increase. 3: With a centrifugal supercharger the boost increases with engine rpm but not quite in a linear way. If it has 10 psi at say 4000 rpm and that is all the boost you want, by the time you are at 6000 rpm you will have to vent a lot of air to hold that 10 psi. If you are pumping more air at the same pressure then the supercharger is doing more work and needs more power to drive it. I have a centrifugal supercharger on my car and it has a valve to vent air to atmosphere. It's there so when under light loads when there is vacuum after the throttle body the supercharger isn't trying to make boost before the throttle body. It's less parasitic loss driving a supercharger that is vented to atmosphere than one that is making full boost that is being mostly held back by the throttle. This makes the engine more efficient at part throttle.
@@HSVR383SC 1: Like I said you can see this first hand by restricting a computer fan or any fan/pump that gives you a rpm output for that matter. If you don't have access to something like that you can also verify it by monitoring what happens to current when you restrict a fan/pump. As the fan/pump slows current will rise. You are basing your opinion on the sound of the shop vac. Mine comes from monitoring data on fans, blowers and many other electro-mechanical devices. 2: Turbine speed is determined by exhaust flow which is a byproduct of intake flow. How can a byproduct increase once it's generator has been decreased or removed? It's a turbo/waste recycler not a perpetual motion device which is impossible in the first place. Is there potential for a momentary rise in shaft speed? Absolutely but unless you were already pushing really hard the odds of it causing damage are very slim. I've never seen a boost leak or blown charge pipe take out a turbo. 3: I never said there would be less parasitic draw since there will be some obviously but how is the below quote any different than what I said. "I have a centrifugal supercharger on my car and it has a valve to vent air to atmosphere. It's there so when under light loads when there is vacuum after the throttle body the supercharger isn't trying to make boost before the throttle body. It's less parasitic loss driving a supercharger that is vented to atmosphere than one that is making full boost that is being mostly held back by the throttle. This makes the engine more efficient at part throttle."
Yep, normally the guys running C02 bottles talk about dome pressure. People who don't want to run a C02 bottle talk about duty cycle with their MAC valve / boost control solenoid.
Interesting vid as ever Steve, would like to hear your thoughts on the current trend in time attack of using a DBW throttle on the intake side of a turbo'd car to control surge
Pounds of boost is measured per sq inch, That round diaphragm looks closer to 2 inch diameter and that's over 3 sq inches of surface area for that boost pressure to act on. Bottom side of that diaphragm has a large shaft on it greatly educing the surface area. So that's some real math required to calculate what pressure is required to tune that valves behavior to your liking.
I've actually seen a lot of videos of the guys at Fuel tech tuning costumers supercharged cars utilizing TurboSmart's new electronic wastegates to control boost with great success. I agree 100% with what you said in the video but this subject seems to be catching a lot of wind in recent months. Now we are talking about cars making hp similar to stuff you work with. Not low hp small blower car on the street. I personally have no experience in the subject as I'm a turbo import guy and always have been. It is interesting to see though. The idea that I'm seeing is this is only working or POSSIBLE to do with Turbosmart electronic gates. Not a standard spring pressure controlled gate.
I disconnected my reference line and it went from 8 to 15psi with a “7psi” spring, only time it creeped above 15 was when i sprayed it with a 150 shot and would creep to 18psi but maintained it
There’s surface area of the gate against spring pressure that come into play. Bigger the wastegate the less it’ll build on spring only. Exhaust back pressure acting on a larger surface area of wastegate valve.
@@danmyers9372 if i pinned the gate shut it would make over 40psi, had it stick shut once and glad i had cheap head gaskets at the time lol. It was a large frame T4 off a Freightliner on a stock 5.0 engine
🤔 so the only other way to have power on fly like a turbo would be to have different timing maps instead of trying to use boost maps like a turbo...???...always heard that you could use wastegates on centri's but I'm taking your advise on the subject.
i'm curious about electronic waste gates and how they work, i'm guessing an electromagnet in place of the spring simply put, but how does the reference and supply line compare into the electronic ones?
Why don’t the gate valve open to the entire size of the gates in/out hole size? I see ppl go to bigger gates to get more control sometimes and seems like if the valve opened as big as the pipe diameter then ppl prolly wouldn’t need to go bigger when them situations arise. If valve don’t open to the actual diameter then seems to me it’s kind of a waste as if gates such an such size then it should open the that size. Like if it’s a 50mm gate but as I see in vid the valve only opens about half way of that gate pipe diameter then you essentially are wrkn with say 40 mm. Just seems that the valving should have twice the range of movement and open the entire diameter up no?
With that being said about superchargers, a quick unloading of back-pressure on the compressor side of anyrhing is going to cause an overspeed. Meaning a blow-off valve. A wastegate can't be used to control any supercharger because it doesn't care about exhaust flow. It's mechanically driven and does what the rotating mass dictates. A blow-off(especially on gas engines) when the turbo is at boost and you come off throttle, keeps the boost(airflow) from reverting off the throttle blade and trying trying to spin your compressor wheel backwards, which will bend blades, destroy thrust bearings, break turbine shafts or explode depending on super or turbo. I was confused about whether you were talking about wastegates or blow-off at the end. Pressure on the dome is an assist on top of spring whether CO2 or air. Air is more efficient because it is what is is when compress it and CO2 is dependent on bottle volume and pressure/temperature.
A wastegate on a Centrifugal SC has nothing to do with exhaust, the WG is placed between the compressor outlet and the throttle blade, whether it is open or closed has zero impact on blower speed provided there isn't any belt slip. If the gate is vented to the atmosphere the difference in airflow through the compressor will be what ever the difference in efficiency is at the given boost pressures and compressor speed. Here is an example using nice round hypothetical numbers. Engine NA consumes 1000 cfm @ 7k rpm, SC is geared to supply 2000 cfm with an engine speed of 7k that will equate to 14.7 psi of boost. Now lets assume that a drop in boost pressure of 1.5 psi (10%) causes the compressor output to go up proportionally to 2200 cfm that means the gate needs to vent 400 cfm so the engine sees a drop of 10% (1.5 psi). Some recirculate the gate back to the intake side of the SC and that can cause issues but I've never seen a problem when vented to the atmosphere.
@@ReEvoluion That's basically what I said without your "Hypothetical " specs. The engine itself is using alot of its natural power to drive any supercharger and if you immediately release pressure from a centrifugal compressor side, the load of the engine will immediately come down and rotational speed will peak like the vacuum example. Turbos won't do that with proper gates because they are a regulated controller of compressor speed based on exhaust flow that the engine hardly cares about and creates a much more linear path of on/off power to the rest of the engine without more mechanical maintenance.
@@hankhank3129 @Hank Hank The engine will not overspeed if you vent the boost pressure. The parasitic draw from the SC is quite small relative to the sum of the driveline losses, aerodynamic drag and rolling resistance. The difference when the SC is loaded/unloaded at the same speed is even smaller relatively speaking since most of the SC parasitic draw is due to friction and the mass of the rotating parts not the pumping losses created by the compressor. The engine also has far less air available to generate power from while all of the other impeders are still present.
You can't make a direct comparison to an electro-mechanical device because the link to the SC is mechanical vs Electro Motor Force in an electric motor which is a balancing act between input (Watts) and output (mechanical impedance). When you restrict a shop vac it does not speed up it slows down. It may sound like it has sped up but that is not the case. I have monitored and maintained many different electro-mechanical systems over the years that had something to do with moving a fluid and not a single one has ever increased in speed when the negative or positive side was restricted.
What’s your opinion and have you tested inlet restrictors on centrifugal superchargers? Ive heard of them used to flatten the boost curve to be more like a turbo and not climb all the way to redline.
@@stevemorrisracing one of my questions regarding inlet restriction is it’s effect on air temp. I’ve see/heard of plugged air filters driving up IAT on turbo applications.
They use a small electric motor of sorts. Engine coolant is plumbed into the E-wastgate to keep the electronic bits cool enough. The heat of the exhaust is what makes an electronic wastegate so difficult to design and build. Without special considerations most electronics will not survive the heat.
When set up as you say, Does the ex. system pressure have any effect on the ability of the wastegate to control the boost? Do you get into situations where the wastegate does not have the flow capacity to reduce the ex. flow/ pressure enough to control the boost?
@@BEANS-O-MATICtransmissions thank you- Ona modern system- like this how much ex/ drive pressure is being used to create 30 lbs of intake boost? How much does ex lobe timing effect ex drive pressure? I.E. have they reduced the overlap? ie closing the ex valve early?
@@benrossbach6501 I'm guessing your throttle is after the supercharger? Use a blow off valve. My vortech setup has one between the supercharger and throttle. Will make it more efficient too.
Love me some insider knowledge videos and nobody does it like Steve! Does the choice of which way you run the exhaust side increase or decrease the cool turbo sounds?
OE manufacturers run the waste gate back through the vehicle’s exhaust so you don’t get the “cool sounds”. Waste gates need to have it’s own pipe that vents to outside air if you want the cool “whoosh” sounds.
The "cool woosh sound" is usually from the blow-off valve, not the waste gate. Waste gate is exhaust side regulation, blow-off valve is intake side. Cool woosh is sudden opening of blow-off when the throttle plate closes.
No, that is a blowoff valve. They are used to vent boost when the throttle blades are closed to prevent damage to the throttle blades. Blower systems have blow off valves only. Turbo systems have both a blow off valve and a waste-gate(s) to control the amount of boost.
thank you for the constant content Steve. the SML build project was spectacular! We all appreciate you taking the time to document the build processes for us. Spreading the knowledge among the wrench bending community is awesome. Keep up the good work
So hard to explain this to a customer. Now I can just say watch this video. Explained by the best.
Great explanation and one I have not heard anyone else offer. So many people talk about waste gates as if we are all experts already. Thanks for taking the time to explain the principles of operation.
Actually with no boost reference it regulates the exhaust turbine inlet pressure only so it is regulating the drive pressure to 10psi. How much boost it will make then is subject to the turbo and engine setup. I have seen twin turbo BBC make 20psi of boost with only 8psi of drive so the wastegate would be like having nothing at all. Now put a 66mm single on and you would probably only see 8psi of boost and like 25psi of drive then the gate would be opening to keep from sending the little single into parts scatter never never land. What you say about needing to control pressures on both sides to prevent an overboost situation or a turbo destruction situation is VERY true.
It depends on the ratio between the wastegate and diaphragm area.
A little simplified. If the ratio is 2:1, the wastegate is adjusted to 10 psi with the boost reference connected and you have a drive pressure of 10 psi then the drive pressure would theoretically need to be 2*10+10=30 psi to open the wastegate without the boost reference.
This is probably one of my favorite “Steve Tech” vids so far. I’ve always wondered if folks use waste gates (or anything else to help control boost) on centrifugal superchargers. Thanks Steve, man I love this channel!!
I believe the item you're looking for is a blow off valve, or bleed valve in some circles.
Bleeding air after you've used mechanical energy to compress it, makes no sense on a mechanically driven air pump, unless it's momentary to avoid surge, when the throttle shuts.
As a mechanic from Australia. Thank you for explaining that. I have had many an argument with apprentices and that explains it really well. Great content.
Steve old truck driver here. My turbo had a waste gate operated by a rod and hose to the turbo. Was told when the turbo reached a certain psi the gate would open and bypass exhaust psi.
That’s correct, the boost pressure is set by a spring only on most diesel trucks. When boost pressure is greater than the spring pressure the wastegate opens and maintains the max boost pressure
Boost reference on the wastegate also prevents overcharging the charge pipes when the motor goes from full throttle and high boost to no throttle (return to idle)...this momentarily spikes boost pressure when all that air has no place to go - but that spike boost also fully opens the wastegate releasing the exhaust pressure on the hot “drive” side of the turbo while the now unbalanced spike on the charge side acts as a “brake” on the cold side, which is at that moment only driven by the turbo impeller momentum. When you control boost only on the manifold reference side of the wastegate, you do so with an (air) pressure regulator which eliminates the closed throttle “spike” action on the wastegate (eliminated by the high pressure regulator) so you have to also run a cold side (manifold reference) blow off valve to release the excess pressure (and make that signature rice-rocket hiss sound on deceleration)...
I can see why controlling boost becomes a true art. Thanks!
Thanks Steve! I have an understanding now, with the new stuff the wastegates are electronically controlled so I’m used to seeing the information based off of voltage. I appreciate these videos they are great for engine theory
I always wanted a variable vane pitch viscous clutch [vaguely like a torque converter] on a supercharger so it could have variable boost with a single fixed ratio pulley arrangement where the boost load [resistance created by natural back pressure] working against the variable pitch vanes of the clutch would set the final boost, and then simply change the vane pitch upward from a lower level to increase boost as the engine needs it.
Also, such a system would be capable of a total [or near total] shut-down in case of emergencies.
In other words, kinda like the fuel cutoff mechanism on a diesel engine [or any engine for that matter] there would be an emergency shut-down mechanism on the viscous coupling that allowed you to completely disconnect it from driving the blower in case of an engine runaway or a crash.
Thanks for the tech videos Steve! They help us broke folks that wanna learn way more than you know! Thanks again
That is really cool about the increased load on a centrifugal sc by using a waste gate on the compressor side.
Counter intuitive.
I think you should make a smx 6 cylinder for us lower grade guys.you can call it the smaxx-6 keeping it around 1600 HP.would sell many.great job on all your projects.pull 2 cylinders off the smx and will be perfect moduler,all same parts.thanks for all the great info.
WW2 fighters before dual stage and dual speed super chargers used to have to be throttled at low altitude to not over boost very cool setups they had back in the day.
Thanks Steve! Thank your team, love you all 🙂
Cheers Steve! I am currently Supercharging my bike and was wondering why people don't have boost control with superchargers. Now I know.
A shop vac with your hand over the end.... it spins faster because it does not have to work as hard, no load , its pushing no air... LESS drag with your hand over the end of the hose. It's counter intuitive , but makes sense if you think about it.
Very informative thanks for sharing
When you first started your business, did you ever think engines would make the power they do now? What's the biggest improvement in the last 15 years?
Nope
Steve is intelligent....From a physics side any science fans out there, look how forward facing, reverse facing and flat blade impellers work for any type of centrifugal blowers. Opening flow can add more CFM and increases the load on an whatever is driving it. I've seen electric motors burn up because a blower hose with x amounts of restriction popped off.
Thank you for sharing your Video on Turbos. Why is their never enough money to build a Motor right, but enough to Rebuild it ?
Makes sense. It's a limiter. Like a compressor for audio, Or a check valve on a water line.
Few other thing I can think of. But my fingers are tired.
Good viddy Steve.
Thank you
Great content thanks for sharing
Thanks for sharing buddy very good explanation
Thanks for the knowledge many racers are unwilling to share
thank you for taken time out to make a great video.
Just remember, every engine feels the fastest right before it blows up. If its too good to be true, it probably is. Infinite boost is only fun for a few seconds lol..
great tech vid, how about one for the BOV? I don't think a lot of people understand what the purpose of the BOV is.
The future is the E gate and those will be the death of the procharger
When controlling boost only through the bottom port you dont restrict the pressure to the bottom port that will cause an initial boost spike then pressure will return to normal the correct way to do it is create an air leak to the bottom port to bleed off pressure
Very interesting video Steve
Don't give up your day job Steve, you made that just about as clear as mud
His explanation was perfect even for a person with minimal automotive knowledge, If you could not understand his explanation then this channel is way above your pay grade! Also you do realize that turbos, Superchargers and waste gates are all part of his day job!
Some people use a controller boost leak on the turbo car to eliminate surge on small engines I've heard
There's also electronic waist gates now-- from Turbo Smart
Very informative as always. Greatly appreciated.
I love learning brother thank you Charlie Western PA
Love the knowledge
14👍's up Steve Morris thank you for sharing this video with us all
Thanks for the video
Makes me so curious because the centrifugal supercharger kit I've been looking into has a blow off valve and a wastegate. I have some questions to ask now, as always thank you for the Steve tech tips they're invaluable to people like myself that just like to wrench every day. J Swap Jason.
Some of them have recirculating air, so instead of compressing and releasing air, it just shoots the air back into the intake instead of atmosphere. Yours may not be quite the same, but that way it keeps air flowing, but under pressure, so things don't go boom.
I think wastegates are typically only found with turbochargers, as the waste gates takes the "waste" or excess exhaust gasses and vents this extra exhaust gasses either into the atmosphere A.K.A: the screamer pipe.
The blow off is typically on the intake/cold side/boost/compressor piping leading to the throttle body. When the throttle blade is open, the blow off is sealed allowing all the compressed and/or intercooled air into the engine. When the engine throttle is closed, a vacuum/boost/throttle position sensor tells either the computer or just via vacuum signal to open this vent to prevent the compressed air from back feeding the compressor side of the turbos.
When the boost gets trapped between the compressor side and a closed throttle, the pressure works against the engines exhaust driven side to attempt to slow the compressor wheel down.
This forced slowing of the compressor while the exhaust is still trying to drive the turbo the other direction ends up causing broken impellers and broken turbos.
Superchargers and prochargers are driven by the engine by mechanical connection, like a belt or crankshaft driven setup. Backfeeding this style boost set up, when it doesn't grenade the supercharger, tends to excessively wear the supercharger.
Im fairly sure the prochargers will use a blow off only to remove excess cold side/intake side boost.
Blow offs only releive the stored boost on the intake side.
Waste gates are on the exhaust side(turbos only) and vent some portion of exhaust to maintain a boost pressure setting.
Supercharger\prochargers change boost pressure by changing the pulleys used om the blower and crankshaft. A small pulley on the charger and big (either tooth count or specifically sized diameter) then the blower is considered overdriven. Driven faster tham engine RPM by whatever chosen amount.
Swap those same pulleys around and the blower makes less boost and is then under driven. Driven slower than the engine RPM.
Prochargers can be a bit different, as I think some rowdy race ones can have their drive ratios and/or pulleys changed to affect the boost curve(somewhat) and also the total boost created.
Turbos need the exhaust side gate otherwise the boost gets trapped and tries spinning the turbo different directions at the same time. Also, venting the exhaust gas, as this is what drives the compressor side of a turbo is slowing the turbo down or controlling boost in the most accurate/safe/efficient way. Assuming the waste gate is the correct size to vent enough exhaust fast enough to keep turbo RPM and thus turbo boost at a stable spring regulated pressure or a CO2 regulated pressure.
There's tons more of the nitty grtitty tech, and I am aware Steve has gone over everything in this comment in this video.
As such, there are newcomers to car modifying getting interested every day. Cmon down, you might be the next person supercharging a 1UZ for drifting down unda'. Or maybe the next person to revolutionize turbo/charger/boost control tech.
Bring out ya hot rodders....
@@threadtapwhisperer5136 gerzybear look it up for a J series. Tell me what you think. I understand how everything works I'm just curious after Steve's video.
If your car is equipped with a mass air meter you must use a bypass valve and not a blow off valve, If you install a blow off valve on a mass air car it will effect how the engine runs!
@@NeverEnoughPyro40 fair enough. But FuelTech ft600 will be controlling the car. So that isn't an issue. Fuel tech uses absolutely density I believe. I'm just curious how this will Affect my particular set up I plan on using.
I have to disagree on multiple points when you were talking about speeds relative to shop vac, blower and turbo shaft.
1: When you restrict the intake or exhaust of a shop vac the motor slows down because it is under more load. This is due to the increased mechanical resistance, the speed of any electric motor assembly is determined by the mechanical and electrical resistance of the system as a whole. You can see this first hand by restricting a computer's fan and monitoring it's rpm with an app such as Speedfan.
2: Opening a blow off valve will not overspeed the turbo. Turbine speed it determined by the volume of exhaust flow which is a product of intake volume. If you lose intake flow you will also lose exhaust to drive the turbine and it will slow down.
3: On a SC setup if the gate is vented to the atmosphere the difference in airflow through the compressor will be what ever the difference in efficiency is at the given boost pressures and compressor speed. Here is an example using nice round hypothetical numbers. Engine NA consumes 1000 cfm @ 7k rpm, SC is geared to supply 2000 cfm with an engine speed of 7k that will equate to 14.7 psi of boost. Now lets assume that a drop in boost pressure of 1.5 psi (10%) causes the compressor output to go up proportionally to 2200 cfm that just means the gate needs to vent 400 cfm so the engine sees a drop of 10% (1.5 psi). I've seen some recirculate the gate back to the intake side of the SC and that can cause issues but I've never seen a problem when vented to the atmosphere. These were street applications that weren't anywhere near the bleeding edge but I can't see it being a problem either way when vented to the atmosphere since the compressor is under less load at lower boost levels.
I have to disagree with your points
1: I'm not sure you have tried restricting a shop vac. The motor speed definitely increases. When you block the flow path of a shop vac the air in the impeller is basically trapped and spins with the impeller as it can't go anywhere else. This is less load on the motor as it is only spinning that air and not moving it anywhere.
2: Steve is talking about a blow off valve on the intake side of the engine instead of the exhaust side. If the engine reaches the desired boost level and then the intake is vented it is making enough exhaust gas for that boost level. If the engine increases rpm / load at this point then more of the intake will need to be vented to hold stable boost but there will be more exhaust flowing through the turbo so it's speed will increase.
3: With a centrifugal supercharger the boost increases with engine rpm but not quite in a linear way. If it has 10 psi at say 4000 rpm and that is all the boost you want, by the time you are at 6000 rpm you will have to vent a lot of air to hold that 10 psi. If you are pumping more air at the same pressure then the supercharger is doing more work and needs more power to drive it.
I have a centrifugal supercharger on my car and it has a valve to vent air to atmosphere. It's there so when under light loads when there is vacuum after the throttle body the supercharger isn't trying to make boost before the throttle body. It's less parasitic loss driving a supercharger that is vented to atmosphere than one that is making full boost that is being mostly held back by the throttle. This makes the engine more efficient at part throttle.
@@HSVR383SC
1: Like I said you can see this first hand by restricting a computer fan or any fan/pump that gives you a rpm output for that matter. If you don't have access to something like that you can also verify it by monitoring what happens to current when you restrict a fan/pump. As the fan/pump slows current will rise. You are basing your opinion on the sound of the shop vac. Mine comes from monitoring data on fans, blowers and many other electro-mechanical devices.
2: Turbine speed is determined by exhaust flow which is a byproduct of intake flow. How can a byproduct increase once it's generator has been decreased or removed? It's a turbo/waste recycler not a perpetual motion device which is impossible in the first place. Is there potential for a momentary rise in shaft speed? Absolutely but unless you were already pushing really hard the odds of it causing damage are very slim. I've never seen a boost leak or blown charge pipe take out a turbo.
3: I never said there would be less parasitic draw since there will be some obviously but how is the below quote any different than what I said.
"I have a centrifugal supercharger on my car and it has a valve to vent air to atmosphere. It's there so when under light loads when there is vacuum after the throttle body the supercharger isn't trying to make boost before the throttle body. It's less parasitic loss driving a supercharger that is vented to atmosphere than one that is making full boost that is being mostly held back by the throttle. This makes the engine more efficient at part throttle."
So putting pressure to the top of the gate is called dome pressure by some??
Yes
Yep, normally the guys running C02 bottles talk about dome pressure.
People who don't want to run a C02 bottle talk about duty cycle with their MAC valve / boost control solenoid.
Quality explanation
Interesting vid as ever Steve, would like to hear your thoughts on the current trend in time attack of using a DBW throttle on the intake side of a turbo'd car to control surge
Good info Steve
Actually seem fairly straightforward
Pounds of boost is measured per sq inch, That round diaphragm looks closer to 2 inch diameter and that's over 3 sq inches of surface area for that boost pressure to act on. Bottom side of that diaphragm has a large shaft on it greatly educing the surface area. So that's some real math required to calculate what pressure is required to tune that valves behavior to your liking.
Great video and great comparison for the procharger
Yeahhhhhh. My first turbo build 25 years ago i definitely mixed up the wastegate line 😬
You ever used lapping compound on the valve and seat to make a better seal?
Boost cut has been around for 25+ years. Use it as it can save an engine.
Thanks Steve
I've actually seen a lot of videos of the guys at Fuel tech tuning costumers supercharged cars utilizing TurboSmart's new electronic wastegates to control boost with great success. I agree 100% with what you said in the video but this subject seems to be catching a lot of wind in recent months. Now we are talking about cars making hp similar to stuff you work with. Not low hp small blower car on the street. I personally have no experience in the subject as I'm a turbo import guy and always have been. It is interesting to see though. The idea that I'm seeing is this is only working or POSSIBLE to do with Turbosmart electronic gates. Not a standard spring pressure controlled gate.
Australian made rite there folks 🇦🇺
Cool, thanks for the information 👍
I disconnected my reference line and it went from 8 to 15psi with a “7psi” spring, only time it creeped above 15 was when i sprayed it with a 150 shot and would creep to 18psi but maintained it
Yeah, how much boost a system will make without a boost reference on the gate depends on the set up. Engine size, turbo(s) size.
There’s surface area of the gate against spring pressure that come into play. Bigger the wastegate the less it’ll build on spring only. Exhaust back pressure acting on a larger surface area of wastegate valve.
@@justins8c252 it was a 38mm gate
@@danmyers9372 if i pinned the gate shut it would make over 40psi, had it stick shut once and glad i had cheap head gaskets at the time lol. It was a large frame T4 off a Freightliner on a stock 5.0 engine
🤔 so the only other way to have power on fly like a turbo would be to have different timing maps instead of trying to use boost maps like a turbo...???...always heard that you could use wastegates on centri's but I'm taking your advise on the subject.
i'm curious about electronic waste gates and how they work, i'm guessing an electromagnet in place of the spring simply put, but how does the reference and supply line compare into the electronic ones?
Keep it up
Why don’t the gate valve open to the entire size of the gates in/out hole size? I see ppl go to bigger gates to get more control sometimes and seems like if the valve opened as big as the pipe diameter then ppl prolly wouldn’t need to go bigger when them situations arise. If valve don’t open to the actual diameter then seems to me it’s kind of a waste as if gates such an such size then it should open the that size. Like if it’s a 50mm gate but as I see in vid the valve only opens about half way of that gate pipe diameter then you essentially are wrkn with say 40 mm. Just seems that the valving should have twice the range of movement and open the entire diameter up no?
Great info
With that being said about superchargers, a quick unloading of back-pressure on the compressor side of anyrhing is going to cause an overspeed. Meaning a blow-off valve.
A wastegate can't be used to control any supercharger because it doesn't care about exhaust flow. It's mechanically driven and does what the rotating mass dictates.
A blow-off(especially on gas engines) when the turbo is at boost and you come off throttle, keeps the boost(airflow) from reverting off the throttle blade and trying trying to spin your compressor wheel backwards, which will bend blades, destroy
thrust bearings, break turbine shafts or explode depending on super or turbo.
I was confused about whether you were talking about wastegates or blow-off at the end.
Pressure on the dome is an assist on top of spring whether CO2 or air. Air is more efficient because it is what is is when compress it and CO2 is dependent on bottle volume and pressure/temperature.
A wastegate on a Centrifugal SC has nothing to do with exhaust, the WG is placed between the compressor outlet and the throttle blade, whether it is open or closed has zero impact on blower speed provided there isn't any belt slip.
If the gate is vented to the atmosphere the difference in airflow through the compressor will be what ever the difference in efficiency is at the given boost pressures and compressor speed.
Here is an example using nice round hypothetical numbers. Engine NA consumes 1000 cfm @ 7k rpm, SC is geared to supply 2000 cfm with an engine speed of 7k that will equate to 14.7 psi of boost. Now lets assume that a drop in boost pressure of 1.5 psi (10%) causes the compressor output to go up proportionally to 2200 cfm that means the gate needs to vent 400 cfm so the engine sees a drop of 10% (1.5 psi).
Some recirculate the gate back to the intake side of the SC and that can cause issues but I've never seen a problem when vented to the atmosphere.
@@ReEvoluion That's basically what I said without your "Hypothetical " specs.
The engine itself is using alot of its natural power to drive any supercharger and if you immediately release pressure from a centrifugal compressor side, the load of the engine will immediately come down and rotational speed will peak like the vacuum example.
Turbos won't do that with proper gates because they are a regulated controller of compressor speed based on exhaust flow that the engine hardly cares about and creates a much more linear path of on/off power to the rest of the engine without more mechanical maintenance.
@@hankhank3129 @Hank Hank The engine will not overspeed if you vent the boost pressure.
The parasitic draw from the SC is quite small relative to the sum of the driveline losses, aerodynamic drag and rolling resistance. The difference when the SC is loaded/unloaded at the same speed is even smaller relatively speaking since most of the SC parasitic draw is due to friction and the mass of the rotating parts not the pumping losses created by the compressor. The engine also has far less air available to generate power from while all of the other impeders are still present.
You can't make a direct comparison to an electro-mechanical device because the link to the SC is mechanical vs Electro Motor Force in an electric motor which is a balancing act between input (Watts) and output (mechanical impedance).
When you restrict a shop vac it does not speed up it slows down. It may sound like it has sped up but that is not the case. I have monitored and maintained many different electro-mechanical systems over the years that had something to do with moving a fluid and not a single one has ever increased in speed when the negative or positive side was restricted.
So the reference line is the one the guys use to put a bleed on to increase boost without using a pressure source on top of the hat?
Yep that's the one.
If u try to control a SC with a waste gate…I imagine it’ll heat up the air a bunch too
Thanks! Are the new servo controlled wastgates any good yet?
What’s your opinion and have you tested inlet restrictors on centrifugal superchargers? Ive heard of them used to flatten the boost curve to be more like a turbo and not climb all the way to redline.
Can work, I am not doing it yet
@@stevemorrisracing one of my questions regarding inlet restriction is it’s effect on air temp. I’ve see/heard of plugged air filters driving up IAT on turbo applications.
Thanks again for the great content. How does the newer electronic gates work ? Are they using some sort of electronic solenoid?
They use a small electric motor of sorts. Engine coolant is plumbed into the E-wastgate to keep the electronic bits cool enough. The heat of the exhaust is what makes an electronic wastegate so difficult to design and build. Without special considerations most electronics will not survive the heat.
Steve have you ever used a turbo rpm gauge.
So why doesn’t someone create a gearbox system for supercharger pullies as a means of reducing pressure?
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When set up as you say, Does the ex. system pressure have any effect on the ability of the wastegate to control the boost? Do you get into situations where the wastegate does not have the flow capacity to reduce the ex. flow/ pressure enough to control the boost?
Yes to both questions. Drive pressure and gate size has an affect on a gates ability to control exh flow/boost ina given combo
@@BEANS-O-MATICtransmissions thank you- Ona modern system- like this how much ex/ drive pressure is being used to create 30 lbs of intake boost? How much does ex lobe timing effect ex drive pressure? I.E. have they reduced the overlap? ie closing the ex valve early?
How about when closing the throttle quickly. Have seen a lot of belt issues. Is there a way to deal with the sudden spike?
Sorry meant on a whipple.
@@benrossbach6501 I'm guessing your throttle is after the supercharger? Use a blow off valve. My vortech setup has one between the supercharger and throttle. Will make it more efficient too.
Love me some insider knowledge videos and nobody does it like Steve! Does the choice of which way you run the exhaust side increase or decrease the cool turbo sounds?
OE manufacturers run the waste gate back through the vehicle’s exhaust so you don’t get the “cool sounds”. Waste gates need to have it’s own pipe that vents to outside air if you want the cool “whoosh” sounds.
The "cool woosh sound" is usually from the blow-off valve, not the waste gate.
Waste gate is exhaust side regulation, blow-off valve is intake side.
Cool woosh is sudden opening of blow-off when the throttle plate closes.
What is the difference between a conventional and an electronic wastegate?
One moves via a spring and diaphragm assembly, and one moves via an electronic actuator.
I've seen vortechs with bypass valves on street cars for when the throttle snaps shut. Is that the same thing he's advocating against?
No, that is a blowoff valve. They are used to vent boost when the throttle blades are closed to prevent damage to the throttle blades. Blower systems have blow off valves only. Turbo systems have both a blow off valve and a waste-gate(s) to control the amount of boost.
No, bov dumps the boost when you close the throttle. Trying to regulate boost at open throttle is what he is talking about not to do.
No new videos, what’s up?
U say hook it up right. I think hook it up wrong and just build a motor to handle 35 lbs lol
7 pounds force does not equal 7psi on the face of the valve. This explanation is way oversimplified.
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STEVE BIULDS ENGINES FROM SCRATCH!! He's not Jesus or God. But close!!