HOOKER CAST TURBO MANIFOLDS VS E-BAY TURBO HEADERS-BOOST PSI VS BACK PRESSURE. BACK PRESSURE VS HP!
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- Опубликовано: 9 ноя 2022
- DO CHEAP, EBAY LS TURBO HEADERS MAKE POWER? WHICH ONE MAKES MORE POWER, CAST IRON HOOKER LS TURBO EXHAUST MANIFOLDS OR E-BAY TURBO HEADERS? HOW MUCH BACK PRESSURE IS TOO MUCH? WILL BACK PRESSURE REDUCE HORSEPOWER? HOW MUCH IS A TURBO CAM WORTH? HOW TO MEASURE BACK PRESSURE. CHECK OUT THIS COMPARISON BETWEEN A SET OF HOOKER CAST-IRON, SINGLE TURBO MANIFOLDS AND THE TYPICAL, CHEAP, E-BAY TUBULAR TURBO HEADERS. WHICH ONE MAKES MORE POWER? WHICH ONE HAS HIGHER BACK PRESSURE? ALSO TESTED STOCK CAM VS BTR STAGE 2 TURBO CAM AND NA VS TURBO ON A 5.3L LS.
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It is a pity the overboosting was not resolved for a more fair x psi comparison on both setups throughout the rpm range. And it would be nice to see a pair of factory manifolds with your usual fabbed up Y piece into the turbo to see how that compares with the merged Hooker setup.
Another successful testing session showing the facts! Good stuff and thank you for all your hard work over the years. It definitely gives guys a opportunity to make a informed decision without having to only listen to the guys selling the products, which would be the better choice for each individual based on what their needs or wants are!
This COMPLETELY makes me NOT regret selling my manifold turbo setup. On to better things now!! Thanks for the results!
I'd like to see the back pressure with one of the wastegates blocked off on the tubular system tested as well.
The change in back pressure and HP in the Hooker system I think is due to the increased back pressure and the wastegate unable to blow off enough exhaust to bring it down.
I also expected the cast iron manifolds to retain more heat energy and drive the turbo harder, and I thought we'd see a better boost number lower in the RPM range, and that didn't seem to happen.
I'm going to have to watch this one again taking note of back pressure reading line location.
Awesome info as always, thanks Richard for your dedication to excellence in automotive performance testing 👍
Hello like minded people
Wassup dude
When did hooker come out with these?
@@I_like_turtles_67 they have been out. Id like to see the summit racing manifold tested with it dual gates and stainless steel cast
@@Fackler91 I realized after clicking they've been around for a few years. Pretty good option for someone going LS turbo route.
Lol .
Great test Mr. Holdener. The back pressure surely could be preventing the turbine from spinning as fast as it could. It could also be diluting the cylinder mixture and acting as a buffer.
Higher back pressure results in less exhaust gases leaving the cylinder, which, in turn, results in less intake air and fuel entering the cylinder, and less power output. On a turbo setup, you need exhaust pressure at the turbo to spin it fast enough to create the boost you're looking for, but any other exhaust pressure increase results in loss of power.
CORRECT ✅
Finally some more dyno videos! Keep em coming!!
Very enlightening as always, thanks Richard
If you’ve watch any of these videos before it was pretty obvious which would win. Richard should run both hot sides N/A without a turbo on them. I think it’s obvious the headers would flow more and make more power than hooker set up N/A but it would be kinda interesting seeing what the difference would be. Anyway as always with all his dyno runs the more power N/A the more power under boost.
Bernoulli's principal. A decrease in pressure = increase in flow. I would guess the decrease in back pressure allowed more efficient spool which allowed the compressor to do I its thing more efficiently. Basically the entire turbo is working more efficiently as the back pressure drops.
drive pressure being lower or closer to 1:1 with boost pressure is just more efficient on the top end. I'd be interested to see cams with high overlap vs none on high backpressure setups.
I think the real interesting thing to look at would be HP/PSI on each engine across the dyno graph since the boost levels weren't even. That would probably somewhat normalize the results, although not completely. Just jam it into a spread sheet and calculate it out, if the dyno software doesn't.
They were both even at 11psi up top so no need to over think it. The free flowing bigger pipes won.
@@3800TURBO Yes, less backpressure obviously wins up top. That's not the only thing that matters. The boost curve on the manifold setup is screwed up. There's no way it should take 6000rpm to reach peak boost and be down 2-4psi until then.
Myself and many others running the hooker setup would really like to see these things pushed further to see data and their limits. I’m making around 960whp with them and I’ve seem to basically hit a wall for power when everything else is good for 1300+. Thanks for the videos.
If you've got an extra input it's not too hard to add a sensor for it. I'd be really curious to see that measured at various parts of the manifold, like at the turbo, before the crossover, etc.
If you've got an extra input it's not too hard to add a sensor for it. I'd be really curious to see that measured at various parts of the manifold, like at the turbo, before the crossover, etc.
Steve Morris has a vid making 1200hp using them so they will make more just need the right setup or base hp to start
Would adding an additional wastegate help, like the tubular system, or alternatively, adding a second turbo and wastegate with it, I'd think you might be pushing the bottom end to it's limits at 1500 HP 😀
I think they got a cork in there some where. Maybe a spot in the casting design that's restricting flow.
Great information thanks for sharing. I ran a big block turbo car for years with a manifold on one side and a header on the other
Mave my 6.0 ls set up the same way
No YT channels talk about back pressure except for Banks. Awesome data.
Now we need a trick flow turbo header test, on a 5.3 preferably
SUGGESTION: measure the BSFC of an engine during runs at various throttle settings. Use a Hellion sytem on a Hemi, which uses full-length headers before each turbo. Find which uses the least BSFC, has the lowest EGT and backpressure, etc. Then use cast log manifolds with the exact same turbos.
Purrrrrfect video...praying this test would go down..thank uuu
Shit, "common" knowledge in some circles was that the turbo was the biggest restriction and the pre turbo exhaust didnt matter much... Seems there might be some error to that. Very awesome test.
I built my turbo setup with that info in mind... Im thinking i may have made that in error now.
Full-Race did a test on one of their 300HP Honda's, and going from Log to Tubular Manifold they picked up 40HP on a little 4 banger. It convinced me to change the header design on my turbo kit.
I would guess the increased back pressure makes the scavenging effect less efficient and leaving more inert gas in the combustion chamber for the next power cycle.
Awesome Tech! Thanks Richard!
For sure the back pressure made a difference. You reduced the pumping loss on the exhaust stroke for the same air flow on the intake. The question is why was the back pressure less. If you measured exhaust temperature and exhaust pressure at the inlet of the turbine that may help figure out why. A guess would be the headers are radiating more heat than the manifolds and lowering the specific volume of the exhaust gas which will equal less pressure for the same mass flow. Probably more to it, could turn into a science experiment real quick.
I'm wondering if the cast manifolds have a cork somewhere. May be one spot where it's just not large enough. Seen this difference even between different factory manifolds on turbo setups.
@@3800TURBO
Thinking out loud - Definitely the contributing factor would be the flow capability of the manifolds vs the headers, but the turbo/wastegate are the governing flow devices, so trying to figure out how the pieces fit together.
I did not see where the exhaust pressure was measured, but if it is just before the turbo, then up stream flow restrictions would not directly cause the pressure to be higher in front of the turbo.
Since between 6000 and 6500 rpm boost conditions are the same, that would mean that compressor power required is the same and turbo shaft speed is the same. That would also imply that the turbine volumetric flow is the same since turbine speed is the same for both cases. To get the intake conditions to equal in the two cases, the higher pressure and likely higher temperature case would require less turbine mass flow to drive the compressor than the lower pressure/temperature conditions. For the turbine side it is an energy balance, in both cases turbo shaft power would be equal, but the higher pressure and likely hotter air will allow more energy extraction and require less mass flow to get the same shaft power.
Long winded way of saying I agree that it is the flow restriction of the manifolds, just trying to figure out the impact to the devices that will most directly impact the back pressure at these levels of pressure and flow.
A twin scroll comparison would be interesting divided vs non divided, single and twin scroll and if it's out there twin turbo twin scroll.
It would need to be done on something other than a v8 where the two inlets can isolate all of the negative cylinder to cylinder interference during each's valve overlap. Having two divided turbos would work on a v8, but only if the runners crossed banks to properly pair them, which is why it's only really done on "hot v" setups with the exhaust in the valley where the intake manifold typically sits. 2 rotor, 4cyl and 6cyl can utilize a (single turbo) divided turbo setup but you won't find any tangible benefit with 8 cylinders since they can't all be meaningfully separated
I'd be interested in seeing a comparison of those two exhaust setups NA and see how that compares. I'd love to see longtubes (whether fancy turbo headers for a race car or typical LTs) thrown in too, all 3 both NA and turbo.
My theory: More back pressure means you're having to drive the turbo harder to make the same boost, which means the engine's ingesting the air with more difficulty because of residual pressure from the exhaust stroke where it couldn't escape as easily due to the flow restriction (or lack of scavenging without header primary tubes) a.k.a. back pressure... I talked in a circle.
And higher peak cylinder pressures(theoretically) although as someone else said, there may be a little more residual exhaust diluting cylinder air composition.
thank you mate, the exact vid i wanted to see!
Yeah Richard! you read my mind 👍this will be interesting! Of course my vote and preference is good fabricated long tube but bolt on cast stuff can be great for an easy street set up
Well done, and would not have guessed this
Very interesting vid for sure, keep them coming Richard.
Would really like to read the real reason , since I’m also working on a turbo (gen 3 stroker hemi) build ….😉
Kinda new to all this stuff but I think it has something to do with exhaust pulses and wave tuning…. Probably would see the same affect NA then … .
Great vid showing how back pressure is not a good thing 👍. I knew it cost power and can hurt boost curves but I didn't know even that little bit of Bp could rob that much power. More air in=more air out=more air efficiently in = more air efficiently out = mo powa!
Hey Richard, have you ever tested a turbo manifold vs a regular manifold (or headers), on a naturally aspirated engine? I think it would be interesting to see how much power the turbo manifold gives up, just so you can install a turbo.
Would also love to see the stock manifolds vs tubular vs Holley manifolds for a bottom line NA and with boost
I think back pressure accounts for about half of the 6% difference in power between the cast and tubular manifolds. The other half would come from increased airflow and the extra fuel that comes with it.
I'm thinking about that time you did manifolds vs headers with a supercharger and saw more boost. That was a weird one.
-- Here's my only hypothesis: Because the exhaust gas is under pressure which makes it more dense, the tune frequency for the header is still valid. You still have that good factory intake. The cylinder gases are still getting discharged to a primary tube that likely holds more volume than the cylinder, so the system is still able to resonate and function properly.
Makes sense - back pressure is bad because during valve overlap you'll have dirty air flowing back into the cylinder and intake. Less clean air = less power.
Would be interesting to see this test with factory cam with 0 overlap.
Virtually all cams have some overlap, including factory cams. Engines don't function very well with 0 overlap.
Richard had the best tech channel on RUclips
Nicely done, I think it comes down to packaging and fabrication skill. I would also like to see a test done using stock manifolds as a budget builder would.
THEY WORK GREAT
@Richard Holdener I have a question. I have a silverado with a cammed lq4 that I want to turbo. Eventually I want to go 408 with a big cam. I'm only planning to run 15psi on both setups. The question, is there any benefit to running a vsr80mm or bigger vs 7875 at that boost level?
Thanks Richard, great product review / comparison. One question I have is price vs longevity.
Exactly. It was no surprise that tubular headers make more power, but they are nowhere near as durable as cast manifolds in a turbo setup.
NA test is needed with the cast iron manifolds and the turbo headers with Y pipe. I think you'll see a significant difference there and thus one of the reasons for the boosted difference.
How exactly do you run a turbo header na?
@@HerrPoopschitz take the turbo off and just run a regular exhaust pipe off the manifold or headers
@@HerrPoopschitz I seen guys run those turbo headers without turbos and just run the exhaust out the fender
@@jmullis78ify Ah. Goofy lazy people. Gotcha.
@@jmullis78ify You don’t even have to take the turbo off, just disconnect the intake and have the engine breathe atmospheric pressure air. That way the NA combo still has a bit of the back pressure, just not as much as it would under load
Great test... Even thought the Hooker manifolds look good, the tubular headers create lower back pressure.. Tubular manifolds for me...
The pressure in the exhaust between the exhaust valve and the turbo is created by the piston pushing the waste gases out on the up stroke. This requires energy from the closed system, more pressure requires more energy meaning less is available for the output. It's a simple conservation of energy equation.
Normally they would say send it to Richard but now, Mr Banks, has done this and calculated the hp that is lost by back pressure ratio.
Richard is the GOAT. Period. Testing and results. Nobody can compare.
Thanks for redoing this video. So headers do work with boost just like cams.
I would like to know if the NA engine sees a similar power difference with the headers vs the Holly cast manifolds.
THIS IS NOT AN NA EXHAUST
@@richardholdener1727 you could still run them both na tho, please lol
@@justin_parks yeah, He does that a lot. annoying...
Didn't this video come out a few months back, turbo headers were the best right ! Glad I have mine.
I would love to see how the cast turbo manifolds like the Summit offering stack up here.
Thanks for sharing your wealth of knowledge with us.
Hey I was thinking it would be interesting to see a comparison between a self tuning/learning system with just basic input like you can do in your garage vs a Dyno tune
That’s a lot higher back pressure than I expected! maybe they aren’t as pretty on the inside lol but my guess the gate is probably the biggest problem and log manifold design’s in general can see some nasty high pressure points. how smooth is the flow to the single gate? I can’t imagine it’s dead consistent
Backpressure definitely makes a difference, but not all that HP is gained just from that. I think probably 50% of the HP gains is from scavenging increase front the longer tubes and smoother air flow.
Only thing OTHER than back pressure (and lower VE because less of the gas is able to leave) I can think of is if there was some more heat transfer from turbine to compressor on the cast setup? That seems like a stretch though. Maybe faster turbine speed due to faster boost response also led to a higher efficiency/cooler charge and better VE too? That’s still a knock on back pressure effect though.
In my mind its the same concept if it were a N/A combo. And you've proven it in other tests where you ran extremely long exhaust tubing. Exhaust restriction robs power whether its attributed to manifold, muffler, or undersized tube dia. they're all causing additional back pressure.
Hey Richard you should try the stock cast manifolds with 2 wastegates and compare to the tubular header manifold
I feel like back pressure is a large part of it, but with those pressure ratios of the tubular manifolds the turbo is going to be spinning much faster. I think that the tubular manifolds put the turbo more into its sweet spot and that made half the power gain. It could easily have shown LITTLE GAIN or even NO GAIN if a smaller turbo was used that has a different "sweet spot".
Help me understand, I thought that, like for like, compressor wheel RPM had a direct relationship with boost pressure. It seems like this is a cylinder filling/ pressure reversion issue.
@@ThomasCWiley compressor wheel speed is same as turbine wheel speed. The veloctiy (air flow) of the exhaust as it goes from manifolds to downpipe is what determines wheel speed. Backpressure is like boost, it is a measure of pressure and not necessarily airflow. You can have lots of boost and little air flow, and also you can have lots of backpressure and little air flow.
I see what you're saying about the turbo being in the sweet spot, but 11psi is 11psi, and the motor picked up 45hp. 40-50HP is actually a really common gain from what I've noticed, Full Race did a test back in the day comparing a log-style manifold to an equal length 4-1 manifold and their honda picked up 40HP. Gentle curves with merge collectors w/exhaust pulses is always going to be better than having the gases make sharp 90* turns. ruclips.net/video/TkOFB2R2sqc/видео.html
I wonder if exhaust overlap has an effect. Would the air charge be more diluted at a given back pressure figure if theres more cam overlap?
Im going to have to watch the turbo comparison video again. Not as apples to apples as it adds the compressor variable.
I could go pull out my chemical engineering fluid dynamics book, but....not sure what I could really calculate without more data. Regardless, yes, I could see the pressure difference making up part or most of the power difference.
Think about a pressure washer, put a big nozzle on it and it moves the same quantity of water as a small nozzle would, but the engine has to work harder to do it. It isn't a perfect analogy because water isn't compressible like a gas is, but you get the idea. Back pressure indicates restriction to flow, which means more energy required to move the same quantity of fluid.
it would be interesting to see what it would be if you stuck a extra gate on the cross over of the hooker set up . but no back pressure results in bad turbo lag so the right size header and cross over is important.
Wow .... Great info. It would be neat to see if the cfm was the same on both from 6 to 6.5?
The back pressure is measured at the turbo flange so the manifolds will not change the back pressure readings. The dual waste gates are the factor. Way back in the eighties we put an extra waste gate in the system to relieve excess back pressure. The exhaust manifold/headers will contribute some HP but the lower back pressure will contribute equally.
Great, great video man! I have to say that area below 3500rpm that you pointed out is important for many of us too when it comes to a street car.
At 78mph my vette cruises at about 2k rpm.
On my Ford Lightning I love the low down power too.
2. I wonder also if scavenging is improved with the long tubes, helping pull out exhaust gasses using pulses from other cylinders, or is that less important on turbo engines because they already have pressurized intake air?
The higher the pressure of the exhaust gas, the longer the primary tube needs to be to emphasize the exact same RPM resonance, because pressure peaks and troughs travel faster in high-pressure air than in low-pressure air.
I say this was a pretty perfect example of pumping losses.
I think it's a reasonable assumption to conclude that the change in horsepower difference is attributable to back pressure change. To me, it raises the question of does the back pressure make it harder for the piston push against the pressure, or does the pressure make it harder for the turbocharger to push the boost into the combustion chamber, or both?
Strsight from schoolbook: if you are for some reason limited to some certain turbo (class rules etc.) that is not perfect for your combination, then use pulsetuned exhaust. If you can use a turbo that gets lower backpressure than boost then use as compact manifold as possible to get all the exhaust energy to turbine.
This guy always has bad turbo match that makes more backpressure than boost. 76/75 never works well, compressor too big for turbine. And 76mm compressor is +1100 hp turbo so lots of wastegating that drops turbine efficiency and makes boost/backpressure ratio worse.
I can only think this is directly related to pumping losses and the ability to effectively evacuate the combustion chamber. I wonder if less exhaust lobe timing would be better on the hooker setup
I think the higher backpressure creates lower HP levels through charge dilution. The less backpressure, the more spent gasses you can get out of the cylinder, letting more of a fresh charge in.
I also think the Hooker system is a great system for a street bound Turbo LS set up. It's much easier to package in a street car. Now if you're running at the track, and looking for all the horse powers, then you would want the tubular, but in a race car you're less worried about how it looks, cutting the car up to fit it, etc.
One thing I wonder though, if you plumbed both into a full street exhaust system, how much would that of leveled the playing field for this test?
Thanks Richard! I am curious whether the higher B/P was a function of the Hooker casting restrictions or waste gate (WG) size? Could a "Y" pipe & flange replace the single WG, then 2 WG's be installed on the branches of the "Y" to see if B/P would significantly drop with the increase in "window" of 2 WG's. Any thoughts Mr. R. H.?
How smooth are the internal castings of the Hooker manifolds? Has anyone tried porting or Extrude Honing? Thanks, Paul from S. Central Tx.
Cold you say - welcome to my world where there is snow in the air and starting to stick to the roof next door. Gotta keep those turbos warm, eh what?
Headers were more efficient at flow. Like you say boost is relative. Air in and air out equals efficiency and power. Take your cake and eat it too. Fun test. Wish the hookers flowed better they're a slick setup. Curious how long tubes would compare to the short tube headers. Also curious if scavenging is still a thing with turbo or if it's mainly flow restriction. And if a collector extension pre turbo would make any change as well. I supose the y pipe counts as a collector extension tho. 😂 As always thanks for your efforts and keep up the good work!
Yes again it’s an air pump more back pressure will effect flow be a good balance of both for high hp I think
More back pressure reduces air flow through engine due to less favourable pressure ratios and also causes higher pumping losses as piston works harder to push the exhaust out
Adding a second wastegate on the crossover of the Hooker setup might drop the back pressure quite a bit.
Ok. Correct me off I’m not dissecting this test properly. The reason the tubular headers produce more hp is because of the exhaust tubes are not in conflict with the exhaust flow except at the end of the manifold but they are directed freely through a pipe. The hooker headers are in flow conflict right at the beginning and creating flow problems. Stock manifolds would be better than the hooker headers?? Something to wonder. !! Thanks Richard!!
well a engine is nothing but an air pump in the end of the day, if you need to push harder to get that exhaust out you use momentum and get a backpreasure that prevents the engine from running as free, so i think it is fair to say that it can be contributed to the backpreasure as it directly work against the engine, a turbo like a supercharger does steal hp, although it is more effective than a supercharger.
i think a interesting thing to have tried would be to get a air compressor and run the engine at the same 11psi without a turbo or charger, but an external air source to see what 11psi and no restrictions of spinning up the turbo would be.
Great info! Great content, thank you!
Any guess of how much more a natural aspirated aluminum headed BB Chevy would weight vs a single turbo inter cooled cast block LS package??
Not sure
I have a stainless steel version of the hooker cast iron turbo header. Got it on ebay, and can't find anymore like it.
Richard, you're using a Holley EFI for the tests right? Why not grab a couple of MAC valves to get turbo control? Once you got the PID figured out you could probably use one of these to really get some some consistent boost levels when testing so long as the wastegates had enough authority. Couold even use shop air to better control it by adding pressure on the gate. Keeping the boost level even would really help on tests like this I think. Wish there was an easy way to measure the CFM into the intke too.
I have gone to a bigger sized AR and gained similar power with everything else being the same so I would say sure the power comes from the reduction in back pressure.
Solid info 💪
I'm curious on if it's the type of merge they use. I'm running an action turbo manifold that's a stainless 3in pipe basically. Pass side dumps into the same pipe the driver side feeds into. It's on a 5.3 now but I'll be moving to a 403 soon and hoping this setup doesn't restrict my power output.
Even though there was no change in AFR, is it possible that there was a greater air mass with less backpressure? Boost is a measure of restriction, not airflow. Could it be that the engine became more efficient and the given mass air was achieved with a lower boost number which would mean a greater mass air when boost was matched? I realize AFR didn’t change but is there enough leeway in the Holley controller that 1lb or a 1/2lb of boost was compensated for in the fueling?
Great video and comparison. I'm curious what the heat differential was between the two exhausts closest to the turbine wheel. Possibly the cast iron sapping more heat versus the header transporting more heat to the turbine? Temp probe would be great to debunk that being that heat and pressure are relative.
THE REVERSE WOULD BE TRUE FOR HEAT
I'd also be curious to see the EGT differential between each setup, given that PV=nRT with more back pressure EGT should also rise I would think as long as timing, a/f, etc. stays consistent. Great video Richard!
Would the back pressure on the manifolds come down if you were to make a bypass pipe parallel to the passenger side manifold. So the merge on the passenger manifold would not be a factor anymore
I Did No Expect That Much Change In Back Pressure! Then I Thought Maybe The Greater Back Pressure Would Mean Greater Spool For The Hooker But It Clearly Did Not. And You Would Think 2 Wastages Would Bleed Off A Little Bit Of Pressure During Spool Up. This Makes Me Think It's Directly Related To The Wastage Amount / Sizing Change. You Figure At Full Song The Configuration With 2 Wastages Wide Open Is Allowing More Exhasut Flow Out The Engine Then Forcing It Though 1 Gate And The Turbo. I Know Diesel Guys Say Adding A Wastage In Some Instances Adds Power Becasue It Allows Some Exhasut To Flow Out While Turbo Still Makes The Same Amount Of Boost. Like It Becomes A Higher Ratio Turbine Housing WOT Full Boost When Gate Opens Allowing Greater Exhasut Flow.
Do you think the dual wastegate helped keep the backpressure down due to better bypass volume? I would like to see the hooker set up with a larger single wastegate and both header combos with better boost control. I think the difference will narrow a bit. What do you think?
We know back pressure was less at the same 6000+, so I don’t see it being a issue having another waste gate. But someone might have a reason that I cannot come up with. Consistent boost numbers should make it irrelevant
@@ZONES89RS running the conservative boost numbers that they are, wouldn't the gates be bypassing the most out at 6000+? There is no doubt the tubular headers are better, I just feel like there are other factors that led to the massive difference in backpressure.
@@2GSpyderTurbo I am confident it’s the sloppy manifolds VS the tubular headers that have a very strict direction and flow.
Manifolds are cramming together exhaust gasses where the headers are directional and essentially helps fluid dynamics(gas).
The dual gates are superior for control especially at higher boost levels. It’s hard for me to wrap around them causing the difference in power. I can see consistency for sure. But 12 psi? That isn’t hardly anything .
Your speed secrets shirt has seen better days lol
IT MIGHT BE TIME TO RETIRE THE OG SECRET SHIRT
I think the lost hp could have been caused by the pumping loss of the piston pushing the exhaust out of the engine due to higher back pressure. But that is a pretty obvious reason so maybe I'm wrong.
When you run log style you have less manifold volume Wich works like a smaller turbine housing. That’s y tubular headers make these changes back to back.
You can stay log and run a much larger turbine housing and will spool faster make more power and torque below the curve and also the same or more total hp
Higher back pressure big changes in scavenging is why the headers do a better job making hp. The runners for each cylinder is even length or close to it so scavenging is same.
Yes, more back pressure is the reason for less power
It is obvious that the tube headers are a more efficient design. You mentioned that the tube headers had two wastegates and the manifolds had one. If the manifolds had a second wastegate installed in the cross-over pipe, would this reduce back pressure some and bring the HP closer to that of the headers? There are two advantages that I think the manifolds should have, one is reliability, two the exhaust should retain more heat for better turbocharger function. But I realize that these two advantages may not overcome the flow advantages of the headers.
I have those hooker manifolds and I can tell you that I’ve gone through 2 passenger side gaskets at only 17pounds of boost. Still wouldn’t say they are bad the car made good power and was a blast to drive just don’t expect high boost out of them.
always thought the log type manifolds will cost some power, mine are custom made headers very interesting
Fun video. I’m a bit confused about the back-pressure. Was it measured nearer to the head or nearer to the turbo? Ideally we would measure it at both places to evaluate the exhaust manifolds. Higher back-pressure should result in higher cylinder pressure when the intake valve opens. This is going to resist flow and reduce the total mass of air going in, or lower volumetric efficiency. The dyno doesn’t lie, there is less torque, so less air and fuel, assuming something else is not stealing power.
It looked like he had a tube right under the turbine inlet, so it was the pressure driving the turbo in these tests, not the pressure at the ports.
One interesting comparison may be spool time, if the Hooker manifolds get a turbo moving from idle quicker (IE: gaslight stomp).
It will largely depend on the total exhaust system's volume, and a bit on how much heat is lost. You can size the x-over on the Hooker much smaller than you typically see (2-2.25") and quite possibly have better transient response. The headers also have much more surface area to lose heat, which Richard has shown will slow turbo response.
@@hydrocarbon8272 The cast will get hotter and hold way more heat then stainless tubular. Think of a cast iron skillet.
It takes power to compress the gasses, so it makes sense to me that you lost power. The backpressure was evidence of wasted energy expenditure. I am curious if a hot side turbine change could help reduce that at all? In other words how much tuning can we find in the hot side without killing response to compensate for less than ideal mechanical limits like exhaust routing.
Yes backpressure will affect power. Higher backpressure the lower the power due to it not moving the exhaust as it should, if it gets high enough you can lose power from it polluting the next combustion cycle because it can't scavage enough exhaust fast enough.
Boost pressure is the same, only differences are the manifolds. Then higher HP manifold has greater efficiency, as the Turbo exhaust housing should be the most restriction in the exhaust path. And back pressure was measured at turbo flange. Therefore the Hooker headers have a design fault somewhere, my guess would where the 2 banks merge into one.
Was about to go back to cast manifolds but not after watching this!
I LIKE STOCK TRUCK MANIFOLDS
If power is relative to flow and restriction is contrary to flow. It stands to reason that any restrictions to flow will restrict power. The tubular system just plain flows better.