99% of headers are wrong!
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- čas přidán 16. 11. 2022
- In this, episode 18, DV explains why why header company's are selling you less than optimal headers even when there are no install space issues to deal wth. AS usuall he deetails the fixes that will allow up to 35 extra HP.
Note - you have never seen anything like this before. - Auta a dopravní prostředky
This gentelman is 100% right on ALL points.
In the early 90's I was a Fabricator in Aussy building V8 Super Cars.
We spent hundreds If not thousands of hours on the dyno and track testing all sorts of header combinations.
We had a 5 litre V8 limited to 7500rpm limit because of CAMS Rules.
So to get every ounce of H.P out of such a small engine took a huge amount of development, even on the intake side also.
We ended up having the engines so finely tuned an 1/8 inch change on just the intake length could cost us 45hp.
All our headers ended up being 4-2-1 with an expansion chamber of the collector to an X pipe, all lengths where based on the heat (Sound pulse) signature of each tube all the way to the X pipe.
If you listen to the engines (Before we had to really muffle the cars) of the higher funded teams (Holden, D.J.R etc) they ALL sound like high reving two stroke V8's, and we where making North of 600h.p reliably all day long.
Awesome to see this dear man share his wisdom 👍🏻
@Jay Riley From what I've seen in my simulations it makes cylinder to cylinder balance a lot better. Exhaust blowdown pulses going the wrong way through other cylinders creates more problems with the inlet stroke (because it messes up scavenging) than having intake runners that interfere. It also lets you run a choke a lot smaller without restriction, protecting the low-mid range without top end cost.
End result: Crossplane cranks with crossover headers make sexy Ferrari noises, make more mid-range torque, and can run with timing closer to ideal (because you don't get as much tendency for one cylinder to detonate from contamination). But it's difficult to get the length short enough for top end power, so on high RPM V8 racecars it's not always worth it overall
5 L V8 "small engine"
@@NicoKyunKyun They are in my world Lol.
Kiwi, we’re those Perkins engineering cars?
@@bmmarshall79 DJR cars. I was on the floor in the early 90's for the development of the E.A V8 Falcon and we where working along side Roush and his NASCAR boys!
I know Perkins was doing the same if not more!!
Guy's - I am so busy doing new videos that getting to answer your questions is getting to be really difficult. Hopefully you will get most of the answers you are looking for in future videos.
DV
Hi David, The information you provide in this video is phenomenal. THANKS for creating & posting it.
I'm interested to know if headers on engines with flat-plane crankshafts need to be configured//built differently than headers for typical cross-plane crankshaft engines.
Please do a follow-up video addressing headers for "flat plane" crankshaft engines. I believe the information would be very interesting & beneficial.
Your consideration & attention are sincerely appreciated.
Best regards,
Ben
Yes great job clarifying what everyone tries to keep a dark art. You covered the typical v8 well. I know you can't do every request but it would be great to have a follow up video that fills in the gaps for other types of engines and for building a 4-2-1. For example primary length/diameter (4), how to choose the secondary (2) length & diameter, and how does this effect the collector/tailpipe (1) length/diameter for other engines as well as the typical v8, as well as any info on step tubes, merge and venturi design, and if they produce any benefits. Would also be cool l to here more on the 9' primary header and any other stories about design successes. Thanks for all the hard work you and others put in!
No matter if you make it or not I am damn pleased being able to get all these real knowledge and partcipate your experience. Many of you guys should do this. So much knowledge is lost forever because young beople show weather interrest for knowledge nor respect for the wise guys. I learned in aviatikn from the old guys. The tricks and bits. We need to learn listening again.
My dad was a race engine builder and machinist (Pacific Northwest USA). His career spanned the 1960's through the 1990's. He did a lot of development and dyno testing (mostly V8's of every make). I know he would have been fascinated by your work. We had a customer that went to the trouble of building a 180 degree header system for a C3 Corvette running in the American SCCA Trans Am series in the 80's. The primaries came up and over the valve covers and back to vertical collectors that went down over the passenger side of the bell housing. They made the engine sound like a formula 1 engine. The pounding roar was completely gone! The power improvement was on par with what your work shows (2-4 percent). That's a lot when talking about the tiny margins we fight for in racing.
Yes' I only recently became aware of 180degree headers 'and how the sound of the engine is changed ' and I finally understood why a 289 in a mustang or fairlane etc ' doesn't sound like a 289 in a GT40.
@mark Hatch, that car was built by Jim McCrocklin, mike Halloran and myself, we did a ton of testing with Dennis Fisher, lots of fun
Holy cow for heat batman. I wonder if that was a concern at all.
@@blackfrost273industries4 We worked with the customer to design a quite elaborate insulated stainless steel enclosure with a lot of ventilation in the firewall and floor.
180* headers usually only work with a flat plane crankshaft. Latest tests prove that the bigger the diameter of the primary tube, the more torque the engine makes at ALL RPM & that an 18" collector is the ideal length. They also proved that running both sides into a Y pipe with a single outlet makes more power than duals or any other configuration.
180 degree headers are the true equal headers. they put the pulses all 180 from the last cyl. sounds more like f1 also, a hum rather than a classic v8 rumble. dude made a set on youtube great video & informative
I learned a lot from David’s books. Very knowledgeable guy with tons of experience.
This is very interesting; the thing I’m finding is, the more I learn, the more I realize that I don’t know.
Thanks for all you do David to give us your help and years of experience; greatly appreciated,.
Thank you for your years of research and passion David. 35 years old and glad I found your videos!
i used to swap headers around on my small block nova quite frequently, shorties, long tubes, tri y's, manifolds etc. always liked tri y's the best. never had access to a dyno but the butt dyno always said they were the ticket on my street cars. glad to see some science back up what i experienced. thanks for sharing i grew up reading your books and am still learning to this day!
These kind of topics are great, brilliant as always. Just re assures me I'm going in the right direction as i converted a set of 4 into 1 headers made for my (4 cylinder, sub 7k rpm) engine into 421s.
Interested to hear about anti reversion chambers as i dabbled with that too.
This is the real practical knowledge that comes from experience, not bench-racing or marketing speil .. Thank you sir for sharing your experience. I'd really like more details on the 2v vs 4v heads. Looking forward to more of your content.
Thanks David for your time to explain all that we should know about.
Really connected with your teachings. Understanding building my winning 2 stroke motors with proper pipe/pulse calculated really brought me to you. I feel like I now have a PhD after reviewing all of your videos.
God bless you sir!
Thank goodness for 2X playback speed.
Great idea! 😂
It is a must to make this video from a soul searching yoga video to a informative one
Lol. Ditto
2x was a bit much for my pea brain to process but 1.5x was a good compromise 😂
Talk slow, race fast !
The wisdom of senior mechanic and engineer. Very interesting stuff. I just subscribed.
Thanks DV! Just finished this chapter in the big block book last night so I did the homework! Starting your small block book tonight
On my 2 stroke racing kart the distance from the piston to the end of the header tube is measured and you can put longer ones on for a different torque curve. Or shorter ones. But it deffinetly makes a difference. This is on my Yamaha KT 100 race kart. I change the h.p from 12 to 16 h.p with different length pipe. On race boats the make tunable headers that move with a lever. Cool stuff. Thank you for sharing your wisdom.
Can't wait for part II. Great job as usual.
Much thanks.
Back in the '50s, Motor Trend or Hot Rod Mag had an article on exhaust pipe tuning with a crayon. Draw a line port to end of pipe, eight individual pipes on V8, with a crayon. This is with the engine warm and the exhaust pipes cooled to ambient temperature. Fire up the engine and run it at the rpm you want peak HP, where the crayon melts is where the pipe needs cutting. I suppose several people would be needed to get this info on one run, or it could take several runs. It might be worth a try to find each cylinder's favorite length. Have not tried it, being a two stroke motorcycle racer, I went with other information.
If you or others try it, let me know if it works.
Good luck on your endeavors!
I thought that was for where to put the x or h pipe for a v engine
That has been debunked several times. Same with x pipe placement, same with header extensions.
thats for 2 strokes.
I have followed your career all my life before the web, I sucked up everything you have shared via print and have several of your books next to me right now, Everybody thought Earnhardt could see air move, You were the Pioneer of Air Movement and traction Your my Hero and a Legend. Thanks, David for not keeping your wisdom to yourself and sharing your infinite knowledge, I have always appreciated it.
Best of the best. Your accomplishments are mind numbing. I majored in auto mechanics in school... Thank God. Just love engines and working on mechanical things of all kinds. I can do my own repairs small or large. Garages are so expensive, I have saved thousands of dollars in my life. Always learning and blessed to find men like you. David you are amazing and inspire me to get even more horse power out of my lawn mower. Engine science is amazing.
Thank you for sharing your hard work.
Cheers to and your health
VERY interesting. From the beginning of time I was always told that a 90 degree engine is the optimum and equal length headers are a MUST. Thank you for clarifying.
Thanks DV! I have always thought equal length’s were BS! You have really put it into perspective for me with which one’s should be different lengths! I have always figured a big torque increase, but didn’t realize the amount of HP increase at high rpm!
It's not exactly BS. It depends on the type of header we are talking about. The top fuel type of header, where each tube is self scavenging, equal length is important. All cylinders are running at the same rpm and have the same resonance. The reason equal lengths are BS in the rest of the world of headers, is that scavenging due to other cylinders is more important than the self scavenging of each cylinder.
@@kart70 Correct there are many more things to take into consideration including merge collector design (which ARE equal length anyway) and overall length etc.
Mr. Vizard, absolutely the best explanation of the flow into & out of and why of the internal combustion engine. Using pressure is genius as I would bet someone made such sensors to withstand the rigors of this environment. But using them in this fashion makes perfect sense. Thank you! This is a keeper for my CZcams save file. In your name sir.
DK, ASE Master Tech since 78.
I got a friend with an h22 engine honda. No turbo. Did a naphin drawing of a tuning tube to install at the collector flange. He installed it while bolted to a mustang chasis dyno. Picked up 10 hp at 6500rpm 265 to 275hp . Changed the sound from a raspy honda with a lot of reversion slap. After it sounded like a healthy big block chevy. The tuning tube used the inertia of the exhaust pulses to stop the reversion. I think it also increased scavenging in the primary.
A twin cam vtec inline 4 sounded like a healthy V8 with triple the cubes and a pushrod cam?
That's an amazing piece of tube.
@@hayden6056 figure out what size your collector flange is. Buy an adapter that takes it from like 3" to 2 1/4. Weld a foot of 2 1/4 tube to it. Slip it in. At the collector. Be sure to have an air fuel ratio gauge to verify which way you need to go with idle transition feed restrictions at 1700 rpm. After that. Primary main jets at 3800 rpm. Then you can see what happens just below wide open throttle under load for the secondary mains. Why not wide open throttle as a third step keep the manifold vacuum above the power valve opening manifold vacuum. With the jetting all done. Then go wot with the manifold vacuum below the power valve rating. So you can see what you need to do with the power valve restrictions.
@@hayden6056 Exactly .I'm calling B.S. on a 4 cyl. anything sounding like a BBC. Ain't gonna happen unless you are on the Really good drugs.
@@lilorbielilorbie2496 I've got four v8's here and 3 different kinds. My poncho sounds sort of similar to my Holden as they basically nicked the design off them but still different.
Then nothing sounds like my LS motors due to the change in firing order and the aluminium heads.
Also my two LS motors sound nothing alike because of exhaust and head and cam differences.
I'm unsure where a 4 cylinder sounding like a big block Chevy went to talking to me about my jetting so maybe is cooked. Especially seeing as the only one that runs a carb isn't running anyway and probably won't be a carb next time around.
How do you fuck so much the sound signature of a "flat plane" 4 cyl to make it sound like a crossplane
Wow!.....your video just popped up.
...I’ve subscribed instantly!
I bought & read multiple times your 1st & 2nd (tuning the mini ‘A’ series books) ...40+ years ago!
Your knowledge & expertise was awesome back then, so without hesitation I will watch & support everything you do...
Regards Tony 👍
When I started watching and getting the jist of where you were going with this video I immediately thought about pressure transducer sensor as a means to graph the pulse. It was neat to see you went the same direction. This is my first exposure to your CZcams channel. Looking forward to watching more.
Fascinating video.
Thank you for sharing your knowledge David.
Your How to Build Horsepower book is very good, and I am a Mopar guy, but concepts hold. Fantastic analysis and presentation.
I found out about your videos when my ex was in a class taught by Marvin & I must say you make very detailed informative videos
Thanks, David.
The great thing about the Ford 2 liter is, it's a non-inerferance engine. Timing belt breaks, easy fix. Reliable, decent power, good on gas.
Great comments on Total Seal. Keith Jones, and Kevin Studeker have been critical assets in all of my racing engine builds. They are hands on experts.
The key to getting it correct it must include the most important fact dual plane puts the pulses not even time period for each side. To get the max flow 4 into 2 then collector and the rest all counts. A flat plane v8 is different. The information he is sharing is spot on.
Thank you, DV; When you do your next video on this could you touch on pairing cylinders for scavenging in conjunction with optimizing unequal length primaries in addition to anti reversion, collector types, and secondary lengths? If that sounds more like two more videos, perhaps you could include the secondary length discussion with the scavenging pairing strategy with the appropriate un equal primary lengths. v/r wh
As usual another excellent education my DV.
I love the idea of setting track records through sheer "drivability"!!!!
Theres a lot to be said for having the torque right when you need it.
: )
Absolutely love your videos, I'm addicted to learning more. My project old peace of family history is going kinda in the opposite direction in performance, but laws of physics still apply.
I''m a diesel guy, drive truck (boss gets the money, I put in the hours, I'm on poor mans budget)
My little Cummins pulls 16,500lb EMPTY camper and horse trailer --- 19,000+ lb loaded camper and horses most weekends up extremely steep off road, logging roads, hard climbs. High country of WA.
Love the sound on my over worked straight pipe Cummins, whistling 32lb of boost, at a beautiful throaty sound 1,800 RPM, blowing out some quite hot EGTs. To say there ain't much carbon build up in my lil 5.9 Cummins.
BUT!!!! I also dearly miss driving my 71' F250, 360. Open up the 4bbls on my Edelbrock 600. I know the first answer will be, go put a 428 or 460 in it and be done. I'm weird about keeping as close to factory original as possible. Just want to tune the most efficiency, torque in what I got, 360 FE.
Factory original (I put on the manifold and carb, single glass pack, Edelbrock cam timing chain with +/- 4 degrees / stock timing keys). Everything else stock.
I'll never pull 20,000lb, but it DESPERATELY needs bottom end torque help, to help pull 10,000lb horse trailer up a grueling 6-9% grade, slow / low RPM - 25mph pull up, off road mountain.
Any short quick advice is greatly appreciated. My thoughts, please correct me where I'm wrong... Advanced cam timing "power curve down, raise compression 🤷", small tube long headers, long collector. I'm still learning... I'm on a poor mans budget.
Can't have something that doesn't do a job, yet I miss the sound of a 4bbl V8 working. Any pointers are greatly appreciated.
Very impressive information David. Currently looking at applying this to an Australian Ford Windsor 5.0 and a Cleveland 351 small port. Same firing order on both. Same objective on both. One is a work vehicle, hauling a load all of the time, the other a 4x4 and tow vehicle. Maximising torque at low rpm for drivability, and fuel efficiency is the objective. It would appear that Ford Australia took your advice to the extreme on the Windsor. The factory 4 into 1 system pipes, range from about 22" down to 4" LOL. The information that you have provided, along with your low noise exhaust video, plus the information in your How to Build Horsepower book, means I have some design directions to follow. Thank you very much. Regards Greg from Perth, Western Australia
Hello Greg from Perth! I have a 351C in a 3500 lbs Ford Mustang 71 and I drove it around with a built engine using Australian 2V heads but did not get very good fuel econ. I tried smaller carb but it ran hot that way which is no good. It had 10:1 compression dished Ross pistons and mild cam. At least it was fun. How is your economy so far on your vehicles? Have you thought of Injection? That and overdrive tranny would probably increase my fuel econ from 8 mpg to perhaps double that but I don't feel like switching fuel delivery. I'm more open to a T5 trans with overdrive. Got C6 now.
My reading has led me to believe that the same people selling headers have a second job of selling camshafts. Header design often locks you into a compromise because it forces you to design for a narrow range. Most people pick too short a tube and too large a diameter thinking they will magically drive above 5K rpm everywhere they go. Engines are dynamic and change constantly.
that's old school thinking. with his headers you can run anything
Fantastic video.
Worth its weight in gold.
Well Done.
Regarding the power gain with unequal length: I think it's stunning to see the effect in the 3000 to 3500 range. Over 5%, almost 7% at best! Imagine a "boost" of that magnitude on your daily driver 😲
My main worry is though: this arrangement will surely ruin the sweet rumble of the V8, as it evens out the pulses...
makes a crossplane sound like a flatplane. so to me is a win win situation
@@Hashiriya985 infidel!
I speculate a factor that is very important to equal exhaust flow is not just the length but also the degrees of turn the exhaust header passage , if we add up all the degrees of turn that occurs in the bends ! you can have anywhere from 180 to over 360 degrees of turning the exhaust will transition through. obviously a near straight shot out of the heads exhaust port is ideal ! every bend creates restriction and turbulence,So in my theory when calculating the length we must take into account degrees of bend , a stream of exhaust gas goes through as it gets more delay through the bends than in a straight path , thus there needs to be a formula that converts bend to equivalent straight path , so we need sum of straight lengths plus our turn coefficient which is greater than 1 multiplied by the center tube lengths in the bends ! reverse thinking to take advantage of this theory , would be to use length and bends to time pulses into the collectors. I wonder if any tuners have performed experiments to study this concept to find the formula for the coefficient table for various header diameters .
I am going to have to rewatch this a couple of times.... great work
Thank you for sharing this David. It's a pleasant review for me, with some extras, as I own and have studied judiciously, many of your books. If you would, Is primary length critical for an inertia pulsed exhaust header? I'm referring to the tri-y 4 cylinder example you showed. If you'd be so kind, as to take it a step further, have you tried a tri-y header on a V8 and do they scavenge at all?
Awesome, awesome, awesome!! I just watched Engine Masters S1 E12, where they tested dyno-tested for the right sized header primary on a street-mannered Blueprint Engines 400ci SBC, with a cylinder head that flows ~220CFM at .650" lift on the exhaust valve. Guess what they found? The 1-3/4" headers made the best power, looking at the entire graph. Yes, the 1-7/8" headers won the HP war by 3hp or so but they produced a funky torque graph down low, compared to the 1-3/4" headers. This matches up perfectly to the chart presented in your video here, David. Well done!!
Mr Vizard you are an engine builders hero and a saint for casting the precious pearls of your wisdom and experience before us oblivious swine. I shall endeavor to stand in the light of your experience so that I may always go faster than the other guy. My hat's off to you, sir.
I've been building exhaust systems starting with lawn mower engine go-karts I'm racing things that others weren't just because since I was about five or six years old. I definitely see where you're coming from and you're the first person I can say thinks pretty much like I do. Working with 2-stroke knowledge keeps me from being put in the box building 4 stroke exhaust systems. People have always hated my designs but have never been able to surpass them. Most of my street cars were straight pipes , very quiet because of properly phased pulses until you got bad. The funniest I ever built was an autocross full-size 69 station wagon with a 390 engine side pipe. That was so two of us and our lady friends could do comfortably the all night rally with special stages. The horrified look of the Fiat Audi VW Datsun drivers was great. I can only imagine your life was every bit the thrill living in the European continent. Chevy small-block tri-y headers 1973 in high school was when I seriously started developing my shut up and listen ability. Have a crippled math teacher with a slant 6 Dodge start I think it was that would eat anything the kids thought they had that was hot. Young ones you need to learn from the Masters 😉
These men know their stuff, keep it coming , gentle men, and thank you both, Andy, and David, proformence is their profession, a labor of love, of going, Fast, and First, the first time,,,,,and the last,
Thank you for sharing your great knowledge.
Thanks David I've had this same argument with a many of other engineers for years and years, I've also proven that there is no difference between or sometimes a gain in the use of a crush bend radius over a mandrel bend. My own testing i used water flow instead of air as the mass flow. Didn't have alot of funds in those days and a water flow tester was easier and cheaper to make. Great video.
BTW, I love Big Block Chevies. I currently own a 1997 GMC Suburban with a 454 that I just built and upgraded last year. About 400 HP now. Not too crazy and plenty of power to get out of its own way.
I realized I forgot something in my comment and I apologize. My name is Jeff Thompson. I'm 63 and live in Montana. Thank you for sharing your valuable wisdom. Jeff
Man, I just left out of Helena a few day ago.
I remember when Walker and Banks did those tests! Wow David, thats a great story! thanks for sharing, never knew that was you behind those awsome walker mufflers! Flowmasters are junk, not mufflers!!!! Always learning from your vids! I learn something everytime i watch any of your videos and I've been around for awhile as well...LOL
Brings back memories of Phillip Smiths old book . Priceless to me.
I literally just punched the air after hearing the intro. This is what I'm talking about. Thank you for sharing!
I have tri-ys on my 64 C10. They fit, were cheap used, they're silver coated and they look cool.
Hello DV, thank you for the accuracy explanation, like always. Can you make one for Turbo headers and maybe also on a plenum size too? At the end fig. is it cylinder No. 7 and 8 nominal and is the Nominal size for the calculation as explained before? Thank you and God bless you.
Great information as always David! I really enjoy your videos and your books. Speaking of exhaust, I have a question for you. Can you build good street power (seldom raced if ever) with mid-tube headers? I am building an '83 Camaro Z28 with a 357 (0.040" over) SBC, Dart Vortec heads (hope to port them per your videos), Edelbrock EPS intake, and the Hooker Mid-Tube headers for the mid-80s F-Body with the full Hooker 2-into-1-into 2 exhaust system. Don't have a cam yet, will need help optimizing that out. Looking for around 10-10.5:1 compression. Any advice would be much appreciated! Thank you!
Hello David, Marc on the Isle of Man here. Thank you so much for your incredible knowledge on this subject and the time you take to put out these videos. I am extremely glad to have found your series and grateful for everything I can learn from it. I wondered if being in the USA you primarily work with V8's or if at any time you intended to talk about the straight 6?
I have an m54b30 BMW engine that I am trying to optimise for open class rally cross and any advice from a time served master engineer like yourself would be greatly appreciated.
I have never seen more adept adept header discussion. Best on CZcams
This man was great friends with my old tech school teachers. Glad I got to meet him
Intake runner layout and A/f ratios also play into the exhaust system. Equal length headers won't flow the same when each cylinder has different amounts of pressure in them.
So glad this video Exists, thank you again David.
I tried 2" Tri Y and Equal length extractors on the mild big block chev in my Holden Monaro.
The Tri Ys always felt as though they made more power.
Spent 2 years modeling NASCAR motors for Hendricks Motorsports, and designing and fabricating headers. We went from 740 to 815 hp in that time, cica 2000. Cup cars were running 9700 rpm, we learned the primary lengths were way long by instrumenting engines on a dynamic and timing the negative pressure waves.
I would trust your info more than his. Actually out there winning races.
The 30% of sound reminded me of the one of the reasons why MP3 files are relatively small. When the audio is compressed it drops the quieter sound waves that most ppl can’t hear under the loud ones.
I kinda got hopeful when you mentioned 4cyl. That you might touch on 6cyl. I’m interested in slant 6’s those things need all the help they can get. 😂
The leaning tower of power needs nothing but gas and time. They will outlive humanity.
When it’s all over the only things left will be roaches slant 6s and 90s jeep cherokees.
Exactly, I'm going to make my own headers for my slantie!
but people like me MP3/compression sounds and all-8 firing i can hear 👂clearly it's the really high pitching wines i can't anymore or at least not as much as im around industrial equipment that changed my ears and or brain tune's it out so lower human-male voice is easier for me to understand ect
there's a bit more wizardry going into mp3 than dropping 'quieter' sounds, it's dropping data that doesn't "matter" as much based on tests on people and stuff like that.
Way back in the day, one of the US "hot Rod" type magazines tried 5 different design fenderwell "headers" for a 57 Chev with a street-strip 327- there was around 50hp difference between the best and worst. IIRC, these were 4>1 designs, so there was even more potential for a 'better'.
Making it even more significant, that was only a 400-450 hp engine and if you project to some of the strongest modern NA engines, that could easily be pushing 100hp!
I went and searched for some more material and saw the child. It makes sense. My condolences, I can only imagine. May things be as well as possible.
I (now) choose pipe off the head based on projected horsepower thanks to some insight by an ex-NASCAR exhaust builder. Assuming long radius bends and a good port-header transition, 1.5" off the head can handle up to around 500hp on a V8. But it needs to step up fairly smartly to not be a restriction. Works well in try-y designs as the primary-secondary join is often where you'd need to put a second step (third diameter) on a 4-1 so the headers just look like the only big difference is a stepped primary. There's a ton more to it than that though...
Step tube headers improve power over the entire RPM range. Tri-Y headers improve torque BUT NASCAR teams ran them(& still does on trucks & Xfinity cars for ground clearance. Nothing new. Mickey Thompson manufactured & sold Try-Ys 60 years ago & Thorley headers STILL sells Try-Ys for trucks, Thorleys don't make as much peak power as 4 into 1s, but they do improve low end torque for trucks pulling trailers. Engine Masters dynoed several different primary tube sizes & proved that bigger primaries make more power throughut the entire RPM range. My buddy runs what's considered huge primaries on his all motor 440ci small block Olds in his 86 Cutlas Super Comp car & it runs low 5s in the 1/8 & low 8s in the 1/4, 60ft times are 1.10. Car ran 7.97/168 with his 555BBC with 4,000ft air
@@bradgriffith4231 It's not just the pipe size where the low-mid gains come from. A lot of it is the collector size. You can't fix the low end of a 250hp v8 (late C3 Corvette for example) with a 1.75 primary by running a 2" choke without restricting it a little in the top end. The expansion of a single pipe into a 4-1 collector then back down to a small choke is too much turbulence. But if you build a new set of headers that start at 1.375 then steps to a 1.5, you can run the small choke without the same turbulence.
The effect is even more pronounced with a 4-2-1, you could go 1.375 primary into 1.5 for the secondary, then use a 1.75 final choke. You can get away with that because the expansion of a single pipe into a 2-1 collector is a lot smaller than a 4-1 and there's less turbulence.
Are those videos here on CZcams? I'd like to watch, see if they tested collector changes as well
Ive just started watching your videos and have learned a lot. If i could make a recommendation, it would be to reduce the amount of animations and cuts in your videos. Specifically the random zooming of the camera. It is quite distracting to ME. Maybe not others but to me it is. Either way lots of good info and always appreciate spreading proper knowledge.
Love video and like. Would like to know if the unequal measurements apply to a SBC with a 4-7 cam swap or would the unequal numbers be different. If so could you provide the information on what cylinders would be different lengths with a 4/7 cam. Any help for other readers would be great also. Going to get headers fabricated soon.
Some race engine header designs took that issue into account. They had tubes from the opposite bank collected to give 180 deg separation of pulses and equal length tubes to provide maximum scavenging of exhaust gasses.
Love your videos, exhaust is just another area that need to be addressed, what are your thoughts on V6 and straight 6, as I am running a hemi 6
Sure, after watching the videos on this 99% headers are wrong, I have to agree with you whole heartedly, I have over 12 years of research and development technology from chemical plants. Understanding what you're talking about is so easy to digest. It is all based on what we used to call a batch process with multiple reactors. And measuring what comes in what's going on through the reaction phase and what is being exitive needs to be measured understood. And then if you're tying all these reactors together, you have to have the ingress. And egress shut up in an opportune manner to where they work in unison to the best yield that you can get, keep the videos up, and I love your work, and I think everybody needs to listen to you and understand your formulas and your pathway to this. But you're right on the money, buddy. Navigator
God that intro brings me back 15 years
That why I love the old 255 Indy Ford snake exhaust engine of @1965...
Buick used a 15deg upward angle on their exhaust manifold, this worked like a reversion dam top side of the exhaust outflow - that 15 degs helped make a vacuum helping the exhaust flow turn on the down flow of those factory cast manifold.
Back in the 80' s there was Aftermarket custom exhaust headers known as AR ---
Anti Reversion
you mentioned the pinto engine, this is where I first heard about you in the late 1080s. I would love to see you do a full feature on modifying the pinto engines as an update to your books. a modern take on an old classic :)
I’m way out of my league. Glad it’s a video. I can watch to overload, stop, and go again later. Learning LOADS. I always just accepted that four equal length into one was best. Hm. It leaves power on the table.
David thank you so much for all your wisdom and willingness to explain things to the rest of us! I'm closely following the mission impossible build Tony, Andy, and you are doing on the 318. I'm a restorer by trade and appreciate all the old iron, my father was a Chevrolet fan for the most part...I personally have gained a love for the old Chryslers; mainly because they seem so much more rare than all the mustangs and camaro's my childhood was laden with :) I have a question: in this video you had cylinders 1&8 as being nominal... but also listed cylinder 1 as being +4". Should one of those be #7 instead? I do not see #7 allocated into a grouping and a typo made more sense to me than the confusion of #1 being nominal & (+4), at the same time. If that's the case then I'm really confused! 😅Thank you again, and God Bless you sir!
Ryan
Absolutely. #7 is missing and I think both #7 and #4 are ones that need to be lengthened. They're both the second in the firing order that come after another cylinder in that bank. 8,4 and 5,7.
Thank you for the valuable info very informative. Note: Please see if you can enhance audio quality of your productions.
Priceless information and guidance.
For performance street use, my favorite headers have been tri-Y design. I wish that was a more common offering. Street motors don't live at the top of their RPM all the time. And tri-Y is a not-terrible answer to the cross plane crank.
My favorite thing about this channel is how well the info agrees with things I know from: being a general physics nerd, building speakers, sailing boats, and aviation.
Also, it's always a "science based" approach here. The dyno is the arbiter of truth.
Dynos are not the arbiter of truth because they don't apply real world loads. I know numerous people with good running Super Comp cars that had them dyno tuned & they slowed down considerably. Went back to their old tuneup & the car picked right back up. Nobody other than some "exotic" spaghetti cars run cross plane cranks in street cars. Ford tried it for about 1 year in the Coyote & went back to a 90* crank. GM is using it in their race only Corvettes. The harmonic vibrations cancel any gain one might get in performance & the Ford cranks were destroying the engines. The longer the stroke, the worse the vibrations. It's the same as 4 cylinders without counter balance shafts, only twice as bad! As far as Tri-Y headers, they're ok for trucks pulling a heavy load but they don't make nearly the peak HP as a correctly designed 4 into 1 with merge collectors & step tubes with merge collectors are even better
The GT40 with the crossover exhaust eliminated the 2 cylinders being close to each other. I believe it alternated the firing order from bank to bank and it spaced all the pulses equally. It also ran the firing order in a circle in each collector to create a vortex.
The formula mentions cylinder #1 twice. Is one of these supposed to be #7? if so, which one? Thanks
this is fantastic! I've been building and racing my own engines for some time now, and I've always felt that equal length headers were wrong!! I just never had a defintitive answer on how the tubes should be altered, as I don't have a flow bench or other appropriate measuring equipment... my question is I run a limited late model stock car, and the headers we use are of the 180 degree type that go up and around the top of the transmission, and are considerably longer than a typical SBC type header... would this formula work for this type of header? I know initial length of primary and secondary tubes are critical, but without the benefit of a flow bench and cylinder pressure reading devices, I'm not sure how i would determine what the proper lengths would be.. I enjoy watching your videos on engine building and have learned a few tricks I am looking forward to experimenting with! keep the great videos coming!!!
Finally someone confirmed to me what I have been thinking for a long time
Equal length is only for even firing engines
LS and cross plane american engines requires unequal length as you are saying here depending on the fact that cylinders of 1 bank do not fire 90 degrees exactly after each other
Some more which require longer and some less which require shorter
With the exception of the 8 to 1 exhaust LS with rotary fire pattern where the collector recieves pulses sequentially in order
In this case equal length is the way to go
All the Subaru engines from early 2000s (and probably back to the 80s) up to 2014 had unequal length headers, really bad but sounded great. 2 of the pulses were running into each other with another right behind and then the 4th dragging behind. They sounded cammed with open headers. Then the turbo models sounded even hotter, until they put "equal length manifolds" on them and now they just sound like a mild engine. Still has a unique sound being a boxer 4 cylinder but just sounds like its neutered now.
Thank you DV for sharing your impressive lifetime knowledge!
if I may, i have a little question of understanding regarding primary diameter depending on exhaust port flow-rating (e.g. 200cfm@28hg or something).
In my mind the resulting exhaust flow mass would be a combination of this exh port flow rating, cylinder filling volume and rpm. which would lead at the end to an exhaust flow mass depending on cylinder peak horse power.
shouldn't the primary diameter be depending on total exhaust flow mass or cylinder max power rating?
All that is what you'll base exhaust port on so as long as headers can flow what the exhaust port can in theory you should be good. Either way if you increase volumetric efficiency beyond what exhaust port can flow then it's the restriction and not the headers.
Good day David. As always a very informative video. observation question. you have listed cal.1 twice and left out number 7. it was pointed out in some comments already but I could not find an answer. as well as the question would you change or carry over the lengths in a 4-7 cam swap for a 2 bbl street stock type circle track engine?
Dallas Wuschke
Great stuff, Sir.
@26:42, you list the length changes for cylinders as:
Cylinders 1, 4,&6 + 4 inches
Cylinders 2, 3&5 - 4 inches
Cylinders 1 and 8 - nominal length
What about cylinder 7?
Thanks.
I believe this should be 7 and 8. Why? Because 1 can't be both nominal AND +4 at the same time plus 7 is missing otherwise.
@@Scarlet_1971_cuda so what you're saying is cyl. 7 & 8 lengths are the base line for the other + and - measurements
@@mfr5725 That is the way I understand what is being presented. Hopefully DV or Andy will chime in as well.
He renamed it to cylinder 1 just to see if people are awake.
the picture of the BBC showed the #5 primary tube significantly longer which doesn't match this
Great info and love the presentation
its amazing how small differences to how the air coming out of your engine can affect performance so much
I always figured that extractors are for the purpose of tuning the length of each pipe so that as the timing of the gases reach and enter the collector individually as to not create a que.
My 351 Cleveland 4V quench chamber heads have about 155 CFM of flow at .550 lift from the info I have. I have “tounge” plates installed before the 1.75” headers. Will the “tounge” plates increase flow or decrease? The Cleveland exhaust floor drops significantly on the last 1/2” or so. So by using your chart can the same be applied to my engine?
DV, I think that a Tesla Valve (the scientist, not the car company) conduit design in a header could assist in solving some of the problems with back-flow due to pulse asymmetry issues that result in collector flow conflicts. Combining a high flow primary of the correct length to smooth exhaust pulse frequency alignment with a backflow prevention mechanism that doesn't significantly restrict flow would free up another HP boost like that achieved with primary pipe length tuning. That would be a fun experiment to try.
I had the exact same thought about the Tesla valve principle.
Great insights DV.
Great info on this channel, but I am so thankful for 1.5-2x playback speeds..
Hello Mr.Vizard thanks again for another super video
Thank you! Would this also result in a faster spooling turbo/changes in eg velocity?
As a twostroke guy I like that content very much!
Mr. Vizard if at all possible any performance tips on the 60 degree chevrolet V6 the 3.4 liter especially thank you for any advice you can provide.