Harley Backpressure & It's Effect on Performance
HTML-код
- Опубликовано: 1 апр 2024
- You've Heard the Old Timer Saying "You Need Some Backpressure..." but Is That Really True?
This Video, with a Few Guests, Gives Some Clear Guidance on How Harley Exhaust Works. ⬇️⬇️⬇️⬇️⬇️ Click Show More Below ⬇️⬇️⬇️⬇️⬇️
#harleydavidson #motorcycle #power #tech #tips
🎬 VIDEO LINK from MotoIQ on Backpressure - • Exhaust Back Pressure ...
🎬 VIDEO LINK from Engineering Explained on Backpressure - • Stop Saying Car Exhaus...
🎬 VIDEO LINK to Gale Banks on Backpressure - • The Facts Behind Harle...
🎬 VIDEO LINK to Backpressure Myth - • Performance Harley Exh...
🎬 VIDEO LINK to Backpressure & Burnt Exhaust Valves - • Will No Back Pressure ...
✅WRITTEN REPORT w/ dB Charts on Harley Exhaust ~ Myths & Facts - www.dkcustomproducts.com/harle...
🎬 **Thunder Torque Video Playlist** - • DK Custom Thunder Torq...
🔗 Thunder Torque Inserts™ Fitment Page - www.dkcustomproducts.com/choos...
🔗 Thunder Torque Inserts™ Product Page - www.dkcustomproducts.com/thund...
🏍️ Thank you for tuning in! Be sure to Like / Comment / Subscribe
✅ Get Your DK Custom Products Here
www.dkcustomproducts.com/
🛒 Our Gear & Amazon
Check out our new Amazon page for the gear we use!
www.amazon.com/shop/dkcustomp...
➡️ SOCIAL MEDIA - CONNECT WITH US
/ dkcustomproducts
/ dkcustom1
/ dkcustom
/ dkcustom
📸 Our Camera Gear: www.amazon.com/shop/dkcustomp...
EMAIL: Support@DKCustomProducts.com
The DK Team 
Авто/Мото
I’m gonna have to share this video on our page! I’ve had customers go back and forth with me over back pressure and the one thing I always say that gets them to finally see what I mean is “think of a garden hose, the water is your spent fumes, the hose is your exhaust pipe, the water spigot is your engine. Open the valve on the spigot to starts the flow, If you kink the hose (creating “back pressure”) it restricts flow of water. If you unkink it the flow is smooth and better. Now If you put a 3” diameter hose to the same water spigot without upping your water pressure “Horse Power” the water will be worse and it will dribble out slowly instead of coming out full velocity like it did with the smaller hose” it really comes down to the design of the exhaust, less bends smoother flow but without a few strategically placed bends you loose the velocity.
Also if you don’t have the power to create enough velocity to push spent fumes out the chamber then there’s no real reason to go even bigger with exhaust.
Yes, we have used that analogy as well! Glad you like the video! Thank you for commenting! MB
You are more talking about fluid velocity and differential pressure in your example and you are correct with your logic. The whole backpressure saga is actually pressure transient, a pressure wave traveling through the fluid. Tell anyone who thinks backpressure is great to stuff a potato in their exhaust outlet and enjoy their performance gain!
@@trailerparkcryptoking5213 yea I know there’s a difference but At times just simplifying it to a customer helps them actually understand it better than over explaining and getting really technical
@@Malavidacycles for sure....if they haven’t had an engineering fluid dynamics class they wouldn’t understand... but if their drunk uncle jimbob tells them something mechanical they spew it as gospel till they die! 🤣
Good video. I recently had new catless head pipes installed on 2022 Tri Glide that has stage 2 cam. Definitely cooler! Throttle response is still good but noticed some loss in torque. In 6th gear and 55-60 mph notice engine seems to lug, where before head pipe change it did not. Have just ordered TTI's to put in slip ons hoping this will help. Two days ago I installed tank lift along with cooling deflector wings. Took temps before and after install driving same road, mph and weather temps. Front cylinder and rear cylinder dropped 25 and 20 degrees respectively. Oil temp down 5 degrees to 220 with air temperature at 86 degrees. Thanks for great products guys. Also have your Nexgen shocks and lift installed. Wife says that's the first thing I should have put on. Wow what a difference in ride and handling. Keep up the good work and videos guys.
Glad you like the video and are seeing all the benefits of having the cooling components installed.
I agree when my husband put the NexGen™ Shocks on our bike it was a world of a difference for my comfort and my back. lol
I am sure you will see the benefits of having the TTI's installed as well! Let us know how you like them!!!
Thank you for your business and for commenting! We appreciate you! MB
I think the best thing you guys bring is just plain truth from a riders perspective. What I personally appreciate is the information that is being passed. You have a got stuff your selling but your not telling us you gotta have this or that.
Here is the truth. Love that.
On my exhaust I have a headers to ditch my cat as I’m a dog person. The rest is stock and I happy with the sound and performance.
Again, thank you for just being guys who speak the truth.
Glad you like the video and have gotten your exhaust how you like it.
We do make parts to correct problems we have or to help with performance or esthetics, but we want to educate other riders and help with any issues they are having! That is why we do so much testing and so many reports.
Thank you for commenting! MB
You're correct, as what is important is gas flow rates. These need to be maximised. But gases have weight and therefore inertia. When the valves close the gases come to a gradual stop, when they open again it takes time to get them moving. If the exhaust pipe diameter is correct you get the best of reduced friction (big diameter) and increased gas velocity (narrow diameter). Remember gases have weight, so when the exhaust valve closes the exhaust gases can keep flowing due to their inertia. Just as they're slowing down the exhaust valve opens again and more gas is pushed into the exhaust. When the gases get to the end of the exhaust and out into the atmosphere the pressure suddenly drops (there's no pipe around the gases anymore) and this sudden drop in pressure is reflected back up the exhaust. If your valve timing and exhaust length are properly matched the wave of low pressure travelling back up the exhaust will arrive at the exhaust valve just as is opens which will help the gases from the cylinder exit the engine even more quickly. However the valve timing interval changes as the engine speed changes (but the exhaust pipe stays the same length!) so there will be an optimum engine speed when the valve timing and the low pressure wave exactly coincide. This is where your peak volumetric efficiency will occur and this usually is where the peak torque occurs. So all this means that your cam timing and your exhaust pipe dimensions need to be thought of together - they need to be calculated to give peak torque at the rpm range you want it.
The people who design the engines know this which is why you can lose power if you remove the mufflers as these are part of the exhaust and part of the design for peak volumetric efficiency. Similarly if you change the cam timing then you will change where the optimal volumetric efficiency occurs and this changes where the peak torque occurs, and as power equals torque x revs, you can change where the power occurs. Of course you will need to redo the fuelling as well otherwise it's unlikely you will be able to take advantage of the changes you've made.
Talking about back pressure doesn't really help understand any of this.
Very good explanation! We talk about the basic concept of backpressure because realistically everything you just explained is not plausible to draw a conclusion on when shopping for exhaust. That information and specs are not readily available and if they were, there are too many variances and QC issues with these engines for the information to be black and white. You seem to understand exhaust properties very well but most do not... so it just leaves more room for error trying to correlate and calculate things like cam timing to exhaust dimensions. However, it is reasonable to assume that if one were to understand how backpressure (while not the end all be all) has a negative effect on exhaust performance and efficiency, they can then make a much more educated decision on exhaust mods and choices. Thanks very much for your informative comment. -DS
@@DKCustomProducts True enough. Which is why I believe most, if not all, after market exhaust manufacturers design their exhaust systems for the stock cams. Any cam manufacturer worth their salt will recommend an exhaust that goes with their cam. My tuner has thirty plus years tuning behind him and has tried cam and exhaust combinations to find what work best. This research costs him money (no one pays him to do it) which is why he is expensive. Also he can't try every cam with every exhaust on every Harley, so he uses his experience to make a judgement. However you're paying for that research and experience and when you ride your bike you'll know where're that money went!
Great channel, by the way.
I understand! We do all our on research as well on everything we do. It is nice that someone else puts effort into helping improve others rides. MB
This made it very easy to understand Good show 👏
Glad it was helpful! Thank you for commenting! MB
Put a drinking straw in your mouth and blow….the velocity is fast. Now, remove the straw and open your mouth wide open and blow….very little velocity. I read this a few years ago and it was a good illustration of how air moves in the exhaust and also the intake. Good video guys.
Good analogy! Glad you like the video! Thanks for commenting! MB
Good video
Glad you enjoyed! Thanks for commenting! 👍😎👍 MB
I've got some Thunder Torques from y'all a while back. They did give the bike a boost and it was fun on short runs. Not my favorite on long rides. That being said they sound awesome so hell I'm putting them back on and sending it to a good dyno. Damn you guys.
Good video.
Glad you like the video and have seen the benefits of having the Thunder Torques installed. What was the issue on long runs that you was having ?
Thanks for commenting! 😎 MB
@DKCustomProducts Power came on a little later then I want it. Just didn't quite fill right. I'm running a twin with a fairly mild torque cam and it's nice to just grab a little throttle and grunt on up the hill. I kept getting overexcited and dropping a gear and the state troopers at the top of the hill always like to say hello. Lol
When/if you try the TTI again, rotate them to a 45° angle. The more free flowing position will effect how soon or late the power comes on. These are universal but not a 1 size fits all... So some tuning may be required for the absolute best result and I personally like mine at a 45°. Feel free to give us a call to discuss further or go over what size TTI you have to see if there is a better size option for your application- DS
@DKCustomProducts I'll give it a try. I've got the biggest diameter you sell because the V&H mufflers on it are huge. If I can save a dyno charge that would be great. Thanks for the advice.
No Problem! Glad to help! Reach out if you need anything. 😎
I had a decattaed head pipe and s&s grand nationals, screaming eagle tuner. Why did I lose low end when I went from a catalyst header to a decatted head? I ended up putting the catted header back on. I also put my se street cannons on the decatted header and still had low end loss.
Could be the tune...that is the other thing you mentioned changing at the same time...so I would not rule that out til you went back to your OEM tune. See video link below.
Regarding the new epa compliant S&S headers. it is unknown what they have done design wise. We have had Quite a few comments from folks with the Gran National Slip-on's that have had good experience with the TTI's increasing their low and mid range torque.
I can't think of any feedback we've gotten on the catted or decatted headers.
ruclips.net/video/wQ6EzilYjiI/видео.html
Thank you for commenting! KP
Hi guys, thanks so much for the information! I bought the TTI's for my 4" Roadshark slip-ons a while ago. But, I haven't installed them yet because I'm wondering if I need to eliminate the baffles first?
That will be a personal preference. I do believe if you are keeping the baffle in you will need the Long Thread TTI's. You can remove the baffle and install the TTI's or you can install the TTI's into the baffle.
If you would like more help deciding what to do you can email our Customer Service and they will help you decide what size TTI's you need and which will better benefit what you are looking for;
Support@DKCustomProducts.com
662-252-8828
Thank you for commenting! MB
@@DKCustomProducts thank you! I forgot to mention that I have the largest ones.
If you are installing the 258 TTI's into a baffle you would need to get the Long Thread TTI'S and install it through the baffle and the exhaust. The baffle material is not thick enough to support the 258 TTI by itself.
Please feel free to email or call us with any questions or concerns;
Support@DKCustomProducts.com
662-252-8828
Thanks for commenting! MB
⚡
😎👍
Got a question on a different subject, are the 2022 have a rear lift kit on from the factory now?
No, Later model trikes (2019+) are not equipped with a lift kit... They simply have stiff, near rigid, coil over shocks that do not sag. Older model trikes were equipped with air shocks that had more sag resulting in a lower ride height. Your trike would still benefit from the Convertible Comfort Lift™ which not only lifts the shock's mounting position but also corrects the shock angle for an improved ride quality. However, for some, this is not enough to overcome the terrible ride quality given by the stiff coil over shocks. The best solution is to replace the shocks entirely . Take a look at this link to see all Trike suspension upgrades we offer, including the Lift kit. -DS
So if I have the Vance and Hines 2 into 2 big radius pipes do I want the standard baffles in or out?
Pull out 🎉
It really matters what baffles you have. If you have the open baffles where you can see through the exhaust you can install the TTI's into the baffles, but if you have a baffle that is restricted or you can not see through the exhaust you would need to remove the baffles and insert the TTI's directly into the exhaust.
The best TTI results will come from the standard open baffles or no baffle.
Please feel free to email or text us pictures looking into your exhaust with the inside diameter about 1-2 inches into the exhaust and we can help you choose what size TTI and weather removing the baffle of keeping the baffle would be beneficial for what you looking for;
Support@DKCustomProducts.com
662-252-8828
Also here is a report we've done on Exhaust that you may find interesting/useful- www.dkcustomproducts.com/harley-exhaust-myths-and-facts.htm
Thanks for commenting! MB
@@DKCustomProducts I have the standard baffles that are open
@@travislohneis224 The 118 TTI installed at the exit of the baffle would work very well... You can even enlarge the baffle mounting screw hole to accept the TTI. This way you would not need to drill any new holes. The 118 series TTI can be found here shorturl.at/cyG35
They won’t dyno tune my 2020 CVO limited with SE-131 Stage 4 with a jackpot decatted headpipe 2-1-2 with TAB Zombie slip on’s? I’m told I need back pressure with lower db? Why?
Hi Mark, It may just be the verbiage the tech is using by saying "backpressure" or maybe he is simply uneducated on the concept of backpressure. This is my personal opinion but my observation is that many dyno operators like to see a certain end result or number. Larger baffles are great for sound but do not do anything notable to build exhaust gas velocity and therefor will not do a great job an bolstering peak TQ numbers in the end. They may even be more difficult to build a tune around but that is something I am sure he could clarify for you. What I am confident of is that if you equip the Zombie baffles with the TTI, and really push him to tune that set up... he will see that with the right configuration the Tabs with Z baffles are comparable to any slip-on. Basically, the TTI will correct any shortcomings of a larger baffle BUT If they will turn down $$$ based on a gross misunderstanding of "backpressure" take it as a 🚩 and find another tuner. DS
Why? Are you in California? Or one of the other States that have adopted the CARB guidelines?
It is possibly because they are concerned about working on a bike that will not meet EPA or CARB standards.
Regarding the comment on backpressure, that is pure ignorance. There is nothing in any EPA or CARB guidelines about backpressure, and adding backpressure to an engine is detrimental.
I would find a different dealership.
Oh, and I would also watch these two videos, one regarding dyno tuning in general and the next one regarding dyno tuning and a 131 Stage IV.
ruclips.net/video/isBHK-Jy7Wk/видео.html
ruclips.net/video/MSqLQl3dDAY/видео.html
Thanks for commenting! MB
@@DKCustomProducts I live in Indiana
Yeah, Indiana is Not one of the 13 States that have adopted the CARB emission standards out of Cali.
As Dwayne mentioned, it is either miscommunication or a red flag that they do not know what they are talking about. Always feel free to email or call with any questions.
Support@DKCustomProducts.com
662-252-8828
KP
Come on loud pipes saves lives! (Bro science bullsh!t)
Volumetric efficiency is the key
lol Loud pipes may save lives, but getting rid of backpressure and upping your torque makes riding feel a little more exciting!!!
Thanks for commenting! 😎 MB
Hey guys
Hey Stewart! Thanks for commenting! MB
I'm sure someone will correct me but I think the important bit is not to confuse back pressure with velocity ,
Thanks for the comment! Your statement is a very good approach to understanding exhaust performance and efficiency. -DS
alright then, I'm going to slap on my fishtails again 😁
Go for it!!! Thanks for commenting! 👍😎👍 MB
What about that lollipop thing that you guys sell the ghost near the end of your tailpipe apparently that creates backpressure what are you guys talking about
No, The Thunder Torque Inserts™ do not create notable backpressure. The proprietary concave and wavy design allows exhaust gasses velocity to increase... creating no backpressure, preventing exhaust reversion, and effectively reducing pumping loss to create a more efficient exhaust system over all. Backpressure is counter-productive in exhaust efficiency.
Thanks for commenting! MB
You may be mixing up "backpressure" and "anti-reversion".
It’s just ppl using the wrong terminology.
I had tab zombies on my 124 with the KW2:2 head pipes.
Ran like shit. Got 130mi on a tank bc it was scavenging all the fuel out below 3k.
Put in mediums and retuned it.
Rides as it should
Dyno chart looks like a table top on the tq curve not the Big Dipper.
I’ve heard many solid tuners use the term back pressure too.
Its everywhere.
Reversion and scavenging and such is too complex. Needs back pressure sounds neat and tidy
Thanks for the comment! I agree that most professionals are using the term because it doesn't really benefit anyone to interject with AcTuAlLy iTs nOt BaCkPrEsSuRe, iT's... I am guilty of letting the verbiage go unchecked when people are using it incorrectly. The Zombie baffles can be made to work well when supplementing with the Thunder Torque Inserts. I know that sounds like a shameless product plug but when you really look into how the TTI improve exhaust gas velocity and compare that to how the larger zombie baffles can rob performance, you will draw the conclusion that such an exhaust insert would correct the shortcomings of the otherwise too-large baffle. We do have a video showing the install process with zombie baffles coming soon, likely next week. -DS
Everything is relative and on planet earth the physics is that back pressure reduces flow. If you reduce flow through an engine then you reduce power assuming everything else is the same. If you put a 1” tailpipe on your truck it reduces flow and power! If you make a change to your exhaust and it changes your performance it’s because you changed pressure transient which is the low pressure wave that at some point in the exhaust system heads back toward the exhaust valve. The most favorable time for the low pressure wave to hit the exhaust valve is during valve overlap so that it helps bring in fresh intake charge for enhanced volumetric efficiency. Anyone in doubt just simply take a college level physics class and follow up with an engineering fluid dynamics class and get back with me! It’s science, but not rocket science!
If you want backpressure then shove a potato in your exhaust outlet and enjoy your performance gain....😂😂😂
LMAO 😂👍😎
Thank you for commenting! MB
Exhaust is confusing 🫤
It can be confusing. Here is a link to a report we've made on Exhaust that you may find useful/interesting - www.dkcustomproducts.com/harley-exhaust-myths-and-facts.htm
Please feel free to reach out with any questions you might have;
Support@DKCustomProducts.com
662-252-8828
Thank you for commenting! MB
@@DKCustomProducts
The thing I don’t get is how do my SE slip ons or any slip ons add low and midrange power
When you can see right through them?
Taking the baffles out or running open free flowing exhaust eliminates back pressure, but then you have reversion. That is where the TTI's come in and reduce reversion and speed up the exhaust gas velocity bringing back the torque.
This video explains this subject very well - ruclips.net/video/pr6z00gL5Yg/видео.html
Thanks MB
Stop interrupting video. You guys did more talking than the men in the video. We should be listening to them.
We agree! Check their videos out. -DS
makes me want to watch more!
Glad you like the video!!! We have a few videos on back pressure that you might find interesting.
Here is a link to two of the back pressure vides that you may find interesting - ruclips.net/video/mZ53YO_RZ0E/видео.html
and
ruclips.net/video/pr6z00gL5Yg/видео.html
Here is a written report on Exhaust that you may also find interesting - www.dkcustomproducts.com/harley-exhaust-myths-and-facts.htm
Thank you for commenting! MB
Would you guys mind switching microphones. It's bothersome to listen to the audio when the guy on the right voice comes out my left speaker and vice versa
Sorry for any problems this caused you! I will pass this information along to Kevin and Dwayne. Thank you for commenting! MB