99% of headers are wrong!
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- เผยแพร่เมื่อ 30 ก.ย. 2024
- 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.
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!!
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 !
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
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
David, you sure know a lot, but boy you talk slow and stray from the subject often. In this case, you don't even give us garage tuners any idea about how to make a header that is close to right for our specific engine. You could have converted your head flow to hp/liter displacement, and indicated what diameter tube to use. You could have given typical ignition order for some common V8's, and then indicated primary and secondary tube length. Or at least take one engine as example and show your theoretical dimensions. None of that practical stuff, so all in all a waste of 30 minuts - sorry to say.
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.
The formula mentions cylinder #1 twice. Is one of these supposed to be #7? if so, which one? Thanks
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?
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.
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!
Your summary (~28:30) shows cylinder 1 as being both +4" and nominal, and is missing number 7. Which 1 should be a 7?
watched a few of these videos and pretty much taking all of this info and flushing it down the toilet as it is not applicable to 99% of all of us gear heads because most of the tech he is spouting about only concerns that 1% of hot rodders willing to spend tens of thousands of dollars at one particular problem at a time. I could care less of all the tips and tricks that are put into an engine crankshaft that costs more then my entire car build from bumper to bumper . Not saying the guy is full of shit just simply saying that all of the information is completely useless to people without corporations sponsoring our builds. To me an expensive splurge is sending a block off to be bored and honed and splurging for the extra money to have it done with torque plate. and to what he is referring to is caveman level machinework.
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
I learned a lot from David’s books. Very knowledgeable guy with tons of experience.
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
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.
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,.
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!
As usual another excellent education my DV.
What about number 7 ...?
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 .
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
Excellent information, DV! I'm looking to do a set of custom headers for my Ford small block and have a question. On the chart at 26:35, it shows cylinder 1 as both +4" and nominal length. Which one is actually supposed to be cylinder 7?
I learn a lot from your videos, as well as Unity's. Thank you.
This. Please reply.
I'm pretty sure you increase the length of the ones that fire back to back on same bank. It would be different from sbf to sbc because of firing order.
@@danielphillips1094 I've been thinking it out - pretty sure you lengthen the primary of the cylinder that fires 90° after a same-bank cylinder and shorten the one that's 270° behind another cylinder. I have no idea at the moment how much to add or cut off, but I'm pretty sure it'll depend on where you want your torque peak.
@@johngregory4801 that sounds right. I think nominal length would be determined by where you want peak power and the other cylinders would be adjusted to even out pulses at 180 degree intervals. I think what you're after is essentially a 180 degree header setup without crossing primaries from bank to bank.
@@johngregory4801 also in order to figure out how much to alter length you'd need to know how fast the pulses are moving. I believe I've seen the 500mph figure tossed around. I'm sure the info is out there, just have to know what to search for.
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
do 4-7 swap cams help to correct this problem? thanks for taking the time to share your wealth of knowledge...
No you are effectively swapping the firing order left to right on the engine making the two hottest cylinders sit at the front instead of the back the pulses are the same
I know you said the numbers (primary lengths) in the video aren't optimum yet and need more research, but for what you've done so far it's a very worthwhile gain. My only question is... are they "close enough" to get similar gains on a small block Mopar? I know no header company is going to spend the time on an engine that's been out of production for 30 years, but I could always have a custom exhaust shop do a one-off set for me based on those numbers.
Just buy Dynomation6 and start plugging in your motor info.
yes, its going to make a gain that's substantial, make note that his cup car engine (the drivers side header) was displayed in this video...is Mopar! The other thing to remember he clearly stated early in this video was that the secondary(collector) length was a much more important factor than most people gave consideration to.
It has everything to do with flow! I’v been in the HVAC industry for 33 years and it’s the same in my industry. Everyone is focused on the efficiency of the equipment I focus on the duct work and air flow.
I've read a couple of his books & he's good to a certain extent but the technology continuously changes. The stuff in his videos isn't anything new & some isn't even correct with today's tech. His video on modifying stock intakes is 40 year old news & so is this header video. ALL aftermarket intakes have his mods from the factory & the mods would be illegal in most racing applications that require a stock intake. A 1" open spacer always helps a dual plane intake & a tapered spacer helps both dual & single plane manifolds. Higher gross airflow isn't always better. Reher & Morrison told my buddy he had the wrong heads, Dart 335cc CNC heads, on his Triple Nickel BBC when R&H screwed up the port matching on his intake by matching it to 355cc heads. They then told him his "mismatched" 555 made 50 HP more than theirs when he sent them a time slip. His ALL MOTOR 87 Olds Cutlas went 7.97/168mph at Phx with a single Pro Systems carb on race gas with 4,000 ft air density. His new Batten head 440ci small block Olds just went 5.47/125 in the 1/8 mile with 3,000 ft air & the converter stalling 1,000 RPM lower than needed first pass out of the trailer with the new engine.
@27:34, in your list, you have cylinder 1 listed twice, at +4 and at nominal, and no #7 listed.
What were the primary diameters? And lengths?
I would think that the gasses changing direction would need to be considered also in optimizing headers.
And 4-cylinder engines would be easier than eights due to crankshaft rod journal position.
And manufactures will optimize headers based on who is going to buy them, optimized engine, heads, etc.
Sorry for your loss.
please do a video about flat plane crank cars, engines like Ferrari F430 ! ( MiNE ! ) i want an ideal exhaust system NO cats, dual exits straight pipes and mufflers w/a valves maybe a yamaha EXUP valve ~ then you can use BIG primary tubes and have GAINS @ low/ mid range AND good output at high RPM !
please try to equalize the volume on your videos! it gets too quiet then too,loud! we love the videos but never know if they are relevant to our ferrari flat plane crank and some US makers have flat plane cranks too ! -mustang ! GM w/ new corvette !
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.
Wait a minute...at 26:30 into the video you show lengths of each primary tube, but where is cylinder #7?...and you list cylinder #1 twice!...Please correct.
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.
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.
There is a mistake at 28:00 minutes.
Cylinders 1 should be +4 inches and also nominal? One of those should be cylinder 7, right? But which one?
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.
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.
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.
Somebody needs to ask David to clarify the primary length formula during the next live chat because cylinder seven was left out and number one was repeated at 26:38.
ok you have 2-number 1s and no number 7 on your chart ?
And a turbocharger negates all this voodoo, Germany proved this 90 years ago. If the "rules" allow turbocharging, turbocharging always wins. Always. Now a stepped, perfectly positioned primary pipes, on a turbo system *may* make a difference, for the most part, a $200 turbo, on a bone stock LM7, with a GT45, will make 700 HP, and 700 ft/lbs, at 16 psi, with factory truck manifolds, easy. You just need injectors, intercooler, and a turbo. A bigger cam, springs, and more boost is an easy 1000 hp. Richard Holdner has proven this time, and time again. Also "Cup cars" operating range is 5000+ rpm, most of the time, it's not a street engine.
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.
Just curious. If an engine is 355 cubic inches and is at cruise speed of 2200 rpms at 17 inches of vacuum. How many cubic inches is actually going into the engine. With combustion temps around 2500f. How much air comes out. I am taking that calculation is in one of your books. Do to many concussions as a kid. Mom made me wear a full motorcycle helmet in 1969 to ride my bicycle. My math skills are horrible. I am just curious about how much it expands.
Thanks David for your time to explain all that we should know about.
I love Total Seal rings. in my last three sbc and current 383 sbc
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.
Can't wait for part II. Great job as usual.
Much thanks.
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.
David, I'm in no position to second guess you, but in the unequal length primary length recommendations, isn't it #'s 7 & 8 that are nominal, not 1 & 8?
My 5 into 1 on an inline 5 cyl is compact, symmetric and 100% right .
Please buy a tie clip microphone .... they're not expensive and would make the audio so-oo much better !
I have tri-ys on my 64 C10. They fit, were cheap used, they're silver coated and they look cool.
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.
I'm trying to my best to follow this for my upcoming build, and I'm getting a little lost. Basically what we're trying to do here is ensure that each cylinder's pressure wave arrives at the collector in evenly spaced intervals. At 26:35 we see our big moment that gives us the exact measurements (although there is an error here, cylinder 1 is listed twice and cylinder 7 is not listed), and it was in trying to apply those logically that I realized that I was lost. With a classic firing order of 1,8,4,3,6,5,7,2, evenly spaced at 90* intervals of crankshaft rotation, this doesn't add up in my mind. Please see my diagram below of cylinders and the number of degrees of crankshaft rotation that have occurred since the previous fire of a cylinder on that same bank:
8 - 180 7 - 90
6 - 180 5 - 180
4 - 90 3 - 270
2 - 270 1 - 180
It seems to me that we should be making the cylinders that fire after only 90* should be the ones that are 4" longer, and that the ones that fire after 270* of rotation should be the ones that are 4" shorter, however this does not match up with the "big moment". I considered the fact that this test may have been done with a firing order swap of 4&7 and perhaps even 3&2, but still it's not making sense to me.
Hopefully Mr. Vizard sees this, or someone else who can clear this up and help me understand.
Figuring out pulse widths is simple math really.
@@johnsnow1355 please share
@@lukeperry085 exhaust pulses have a known velocity so it's a simple math calculation of time and speed to know where the pulse is at a given time
@@johnsnow1355 can you please elaborate more? I have an in-line six cylinder engine, and I am designing an unequal headers, the firing order 1 - 5 - 3 - 6- 2- 4 it’s a Nissan tb 48, it’s going to be a true duel exhaust , so therefore two manifolds will be available, first manifold will have its primary tubes on 1 5 3 and the second one will be 6 2 4, I am doing this to get the scavenging.
I want to avoid the pulses from hitting each other.
What’s the ideal situation to get the most of it
@@johnsnow1355
“exhaust pulses have a known velocity so it’s a simple math calculation”
Apparently it’s a simple math calculation that you don’t know or are unwilling to share. 🤦♂️
Your last chart( the one in purple background) showed the 1 & 8 headers as nominal in length but I believe that should have read 7 & 8.
Correct me if I'm wrong but the was no 7 in the chart.
The wisdom of senior mechanic and engineer. Very interesting stuff. I just subscribed.
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
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.
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
Thanks DV! Just finished this chapter in the big block book last night so I did the homework! Starting your small block book tonight
At the end of the video your primary length results say 1 & 8 should be nominal length but cylinder 1 is also listed in the +4 category and there is no mention of cylinder 7 length. In assuming one of the 1's is a typo but which one? Thanks.
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.
Thank you for the valuable info very informative. Note: Please see if you can enhance audio quality of your productions.
Hello, I'm new to lern suche important stuff. However I'm looking for a headers for 3.0l stright six. I know that ELH is a way to go. But I'm chasing sound more than HP. Should I use ELH without secendery pipes? Just 6-1? I know that they should be stepped but this is a place where my knowledge ends. Can someone advice me on this subject?
Thank you for sharing your great knowledge.
Could you make 3 and 5 the same length and increase the length of 7 and 1 to resolve the issue? The other side would need 4 and 6 to be longer. Could that be a possible solution? Also what is your thoughts on stepped headers and having the last step the same length on all the primary tubes so the pressure wave helps scavenge the cylinders equally?
Great question. I think if only picking one to fix it would be making the #5 shorter. Most full length headers I looked at (since learning this) has the #5 tube often longer than #7! Maybe they used the theory in reverse and have #7 beating #5 to the collector! Lol. But seriously, now I can't get it out of my mind as a concern.
I was hoping you could address a few question's I had from this video:
1.) Would you apply the primary lengths changes to "balance-out" a 4-2-1 design / would it provide similar benefit?
2.) it seems a mistake was made in your presentation given cylinder #1 was listed 2X and cylinder #7 is missing?
3.) If mistype occurred, THEN wouldn't cylinders: 4, 6 & 7 = +4" longer , 2, 3, & 5 = -4" shorter, and 1 & 8 = nominal?
Any feedback you're willing to provide is GREATLY appreciated; keep up the good work!!!
I have the same questions like you. Have you found someone that has answered them for you?
@@frz_64 this YT-video has the math on calculating the lengths and better describes why
th-cam.com/video/Qp-I-csOcxo/w-d-xo.html
@@frz_64 yes; a YT-video called "unequal length headers - will this work" has the answer
@@ericschumacher5189 ok nice. i will search for it
Your How to Build Horsepower book is very good, and I am a Mopar guy, but concepts hold. Fantastic analysis and presentation.
The formula you put up you put #1 cylinder twice and no #7 cylinder...did you mean #7 and 8 nominal??
Also the headers you tested did you use your formula that you put on here??
Watching this to learn how to adapt my system on a VFR800 V4 VTEC Honda motorcycle. Any suggestions people? I will also be looking at adding stepped 4-2-1 system with Davids advice from this and other videos.
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.
I find this interesting. My understanding is that unequal length headers are a solution to the problem of high pressure pulses which exist when exhaust pulses from at least two cylinders are both expelled into the same tube within a close enough time period that they partially “collide “, for back of a better term, causing extremely high pressure waves.
But isn’t there another solution?
What if individual tubes have enough volume that they simply CANNOT collide??
If the volume of each primary tube is equal to, or greater than, the volume of that cylinder, the pulses CANNOT stack, can they?
As an engineer, I think this question of primary length is not the right question. It is a question of VOLUME, isn’t it???
Primary tube DIAMETER should be maybe 2-3 mm larger on interior diameter than the optimum intake diameter on the head (determined on a flow bench).
Once the primary ID is known, then the length that results in a volume equal to the cylinder volume can be calculated.
There is another piece, that being that cylinders are never 100% filled. Typically, cylinders are about 90% filled, not 100%.
Now, if you have secondary tubes, this is where pressure pulses COULD interfere, but not on 4 or 6 cylinder engines.
What are your thoughts??
I wouldn't subscribe to this, cause I know soooo much more. I build headers better than F1 and if anyone wants to know more just ask me. I make car engines rev like motorbikes 😅 and I discovered magic in exausts. I have helped build the most powerful engines in their classes in Australia 🌏 but I don't expect you to believe me. My customers are laughing with 30% more power than Aussie champs in any racing formula! And I will give you more real information than this guy in 5mins, and you won't need to fast forward the video 😢😮😅😅lol. There are secrets out there and this guy only knows 10% of them. And I can do it cheaper than anyone! Just ask me, no cost at all 😅
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?
On the first line “1,4&6” should read “7,4&6”. Assuming a 4” stroke and 1-8-4-3-6-5-7-2, the odd cylinders “hit” 1xx3x57x (the x’s are just even cylinders). The 3 and 5 should be the same length as each other (180 degree cad or 4 inch “pulse”), and 5 and 7 should have a longer pulse between them to even out. I am a little surprised that the extra length is needed at all on the odds, since 7 and 1 are spaced 180 cad apart so it seems like that would work if they were the same, but then again I’m surprised 2” wouldn’t fix the difference since there is already 90 degrees cad separating these and that’s half a stroke. So maybe a different way to get the same result would be 1, 7, 2 & 8 equal with 3 & 5 maybe 2” shorter and 4 & 6 set 2” longer? Maybe I’m way off here? I didn’t account for multiples of wave travel per stroke for instance, nor did I account for the air column length as it’s squeezed through the valve opening.
You're right everybody has it wrong but you have it wrong too. Equal length does not mean the pipes are all the same pipe length but equal "Flow" length. Every bend changes the flow length, and the amount of bend changes the length. There are charts and formulas to determine pipe length. Every bend lengthens the pipe flow so you add or subtract pipe length varying on the number and degrees of bends so all pipes geometrically flow the same. My 1968 Motor Manual went into great details about this. This is stuff everybody overlooks and nothing new. This geometry is also used in several other industries Water, Air and Gas and others
I have your Book from Cartech on Holley's, I seen a Cartech book on Camshafts, I was hoping it was from you but it is not. It is by Bob Godbold. Do you think he is any good or does he know his busness. I watched your video about Cam center line and all, but was looking for a good refrence book on Cams. In you opinion is that Cartech book on Cams any good??? I have always built my motor for Torque and not HP. I have a well built 351 Cleveland, I wanna run a Air Gap intake with long tube headers. I have always run the Sig Erson TQ Cams anywhere from a TQ 20 - 30 - 40 and 50. My favorite one by far was the TQ 40 with the Extremely hard pulling mid range from something like 2500 to 5500. Now since these were hydrolic and most say go with Hydrolic Rollers now. I wanna say 220 to 228 and the Center line is 110. So I am stepping up from the Factory 4V head to a Trick Flow head. I was wondering what you think would be a great Torque Cam in a roller Cam shaft, I have 7.3 roller rockers with Guide plate and all from General Kinetic that I had on a shelf for years so I am using those. Something with tons of torque though. Any suggestions. Thanks Kurt Vara.
If 4-2-1 is so good on a 4-cylinder, how would 8-4-1 work on a V8? basically, it would pair cylinders 360-degrees firing interval apart, then merge those pairs, leaving you with 4 secondaries that you would further merge into a single outlet. Furthermore, is there a practical limit to the amount of primaries or secondaries you should merge into a single collector? IE, are straight 6s and V12s with 6-into-1 headers doing it "wrong" in general, or at least "wrong" if below 8000rpm?
And for V8s and V10s should you never do an 8-into-1 or 10-into-1 header? There's also some madman out there doing a 12-into-1 header to try and get 1990s F1 sounds out of his car... Is THAT too much for one collector? Furthermore, when it comes to the nice smooth merge collectors vs the flat baffle/crimped-on looking/"dump" collectors, is there any place for usage of the latter, or should you always try to make a merge collector with the little spike in the middle?
Interesting but the Right side (The Unequal Length header side) Photo Seems to show Chevy cylinders Front to Rear 1-3-5 -7 with #5 having the +4 Longer (Looped) primary Length doesn't agree with Unequal tube Chart (24:05) showing cylinder #5 needs to be -4.......Anyone else notice this doesn't seem to match or am I twisted ??
I know you may not comment but I did learn of this on another channel on TH-cam, but it did not occur to how the unequal firing of a corss plane engine could be addressed as far as the exhaust is concerned.
Not until now.
Lastly, I do not know who Jacque Vizard is, I hope I spelled that correct, but it is NEVER a good thing for anyone to pass away very young. She certainly deserved more time.
@David Vizard Mr. Vizard. The chart doesn't show what length cyl #7 should it be. Could it be the same as cyl. #5?
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!
26:40 should that be 7 & 8 nominal?
Ahhh! Only $15,000! I can probably dig that out of the sofa between the cushions...
IIRC Smokey Munich said to stop thinking of it as an engine and think of it as an air pump instead. Then, you will begin to understand how to find power robbing restrictions.
YOU ARE THE MAN!!!
😁
im trying to quiet an Airplane Engine!
any thoughts???
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!
Building induction and exhaust is a complex process. People talk about back pressure, which is wrong. It's all about scavenging & resonant frequency shock waves, which travel at the speed of sound & change with temperature.
And all headers don't do anything except make noise. TURBOCHARGE !! It's the only way to go !!
(V8, mostly) headers and x-overs are the equivalents of PAF humbuckers in (Les Paul, mostly) guitars
I have been saying this for 22 years! Im only 41 so half my life. Im a 2 stroke guy and i know pipes for that. And pulse is so important. I have never thought equal length headers were a good idea. Never made sense to me. The timing is wrong.
There is nothing more importand than flow. No matter of intake, load exchange or exhaust. That is the personality of an air pump. And flow is dmn hard thing to understand. Nowadays Navier Stoke does a good job and FEM flo sim is pleased with huge calculation power. Bjt these gjys had to devlop feeling for the flow. Design according simple rules, trial, error, loop until perfect. These were the days when engineering was fun and bean counters sucked same like today but those guys did not let themselves impress by them and did the right things anyway.
Be curious to know how this differs crossplane to flatplane.
So the on screen formula half makes sense but #1 is listed as both nominal and +4". The logical setup would be inside vs outside pipes. This would be calculable by the fps of exhaust gas flow so the timing of the gas to the collector should be predictable. Only issue is how much spent gas remains, vs how much vacuum the collector can pull. Ie, how much gas must the exhaust gas push on in front of itself. Pulse timing is all mute if the flow gets there at the speed of sound vs the speed of gas flow and the speed of gas flow is only possible if the system is relatively in a vacuum which should be possible in a race situation so ill go with it. Basically the issuse is that on a 90 degree cross plane crank v8 the cylinder timings are 180-90-180-270... Well its circular and that might not be from 1 in the firing order but i listed it this way to make a couple things easier to see. so there are always 2 pairs at 180 (out of 720) but those 2 pairs aren't 180 from each other. There are also 3 270 pairs. if you skip over to the far side of the 90 degree gap with your pairs you find 2 extra these 2 extra are the ones youd nornally use on a tri y but i suppose inside vs outside could make more power on that because the cylinders can chase the tail of another, sometimes things that arent even are still good because it can help to get the energies interacting instead of isolated but 90 degrees is generally considered too close. When you lengthen the trailing cylinder of the 90 pair you put it less than 180 from the next cylinder, that may be better than nothing bot for a true 180 all around like most 4 cylinder engines you also move to cylinder 180 from the cylinder that you intend to move to fix the 90 situation. Since all common cross plane v8 cranks are designed roughly the same this amounts to an inside pair and an outside pair. So on any particular firing order the mathematically ideal situation would be that anything done to 1 is done to 7. Anything done to 3 is done to 5. Anything done to 2 is done to 8 and anything done to 4 is done to 6. While i do see some of that in davids results its not all around so i wonder if they tried the mathematical way and maybe say something they didn't like or if they started with the transducers and pushed things around till it was good enough? Anyhow as far as i can tell with any firing order you would have 4 long pipes that would make an even running 4 cylinder and 4 short pipes that would make a different evenly running 4 cylinder. The groupings would be 1,4,6,7 and 2,3,5,8 same as you would combine them into a 180 header but only to simulate a 180 header (at a specific rpm, though it should help at all rpm) using separate banks which should help avoid excess lengths to make a true 180 header. I actually thought because it works out to inside vs outside you could use the extra pipe as part of an asthetic design and make some squigles or loops with center exits like some block huggers. If you placed everything right you could have a heart like appearance. This could be marketed with the old heartbeat logo they used to use for chevy as the heartbeat of usa. I almost don't want to post this so i have an oprotunity to make prototypes but i just don't have the time for that. Please credit my comment here if you market that and people buy it.
Liked the video, and agree with your points purely from a torque / HP band perspective. But (and you allude to it yourself in the vid) all the distinctive throb and personality would be removed from the exhaust note. That is sometimes the main reason people buy V8s.
Oh, Total Seal. I thought initially I was hearing toad and seal. You Britisher's .,. with your crazy accent. And your no "the's". 🙃
Hi ty for video.. so for my inline 2.5 bmw what would i want to do for best output? I also wanted to do a unequal header for the great sound.. but also im not out for hp.. so much as improving torq. If even possible an that sweet subaru sound!! Bcuz i love that.. it isnt a fast car an it never will be but i wld like to get something out of the header.. maybe more than sound i.want so bad
Ty if you can or will help.. if you read this by chance of our good lord in heaven.. eegerly waiting!! Ty so much!! You kick ass!!
Most...if not all..."professional" video productions know how to spell 'lengths"...
Absolute legend 🤙🍻