I've only read a couple of magazine articles that make a reference between dyno headers and chassis headers. The former always giving better performance.
The same holds true for the short headers that you have to run to pass your tough smog laws. Dyno Don builds one hell of header from what I hear however, it is still a compromise to what the engine wants.

 

Thats my car/exhaust system which is currently being ceramic coated. What do you want to know?
Here is a pictuure of the complete setup.

 

I'm doing the same thing using my time slips and the dyno program. Since my car is relatively slow (13.4@102) it responds well to mods as there's little tire spin with drag radials. I can compare real world info with theoretical data. My current exhaust is terrible.

 

[QUOTE=DTL504;3712342]Thats my car/exhaust system which is currently being ceramic coated. What do you want to know?


Did you get to the track before you disassembled your setup?

 

You guys are BEATING this exhaust thing to death, AND RIGHTFULLY SO!!!
Follow what pipemax says to the letter and you will NOT be disssapointed!
You are thinking it out correctly.
Terminator boxes will be a definite clearance issue and will have loud interior resonance, but will help with building a "lossless" exhaust, because any pipe you install behind the boxes will be "invisible" to the engine. This method WILL work IF you have the room, but will be very difficult to fab on our cars.

I want to say something about pipemax and how it helped me.
Larry has done his homework! I have Hooker long tubes. Pipemax suggested 1-3/4" primaries (actually, 1.739-1.864) so the Hookers were a great match to start with, but the primaries were too short and the collectors were way off of pipemax's recommendations. Pipemax predicted a primary length of
28.6" and a 3.44"collector 16.6" long. The Hookers primaries are not all equal length (and far from it), so I averaged them out and figured how much length I needed to add to get to an averaged 28.6" primary length. I cut the collector off and painstakingly welded the needed primary tube length. The
3" collector was too small according to pipemax and was too short at 7" anyway, so I welded on the closest size I could find...a 3.5" collector. I followed the program as close as possible and made the 3.5" cut out DUMP at exactly 16.5" as recommended. A tapered cone reducer helped adapt the other side of the 3.5" cutout to the true duals/spintechs dumping at the rear axle because that was cheapest for me at the time.
What a DIFFERENCE!!! Like a two stroke dirt bike, you can actually hear (and feel)the pipes "come on" about 1500-2000 RPM before peak power and the torque improvement is substantial according to the butt meter launch-o-tron. You can feel a pronounced difference in torque from 4500-6500. 6500 was the RPM I was using pipemax to "tune" to. I can't wait to get proof on paper via drag stip, dyno, etc. I already know it was well worth the 40 bucks for the program!
You guys are on the right track!
When you figure it out, you'll be glad you went through all that work and it will be worth it!
Good luck!
Hope this helps!
-Jesse

 

It's a lot of fun too.
We've done experiments with two stroke engines and expansion chambers and that's precisely what I'm trying to achieve with header tuning.
Thanks for the data.
Looks like I'll have to cough up the 40 bucks for Pipe Max.

 

Hey, guys!
Just something else to think about...I have a 950HP carb. Before all of these exhaust mods, my intake tracts were dark brown (reversion). My plugs were sooty and brown as well with only a 72 primary jet and a 78 secondary jet.

Now plugs are super clean/like new looking with a 83 primary jet and an 88 secondary jet! Intake ports are much cleaner! The needed jet increase is proof of more air flow through the engine!

Thanks to Larry and his Pipemax program!
-Jesse

 

I have a reversion problem too however my plugs are sparkling clean. 20 mpg hiway too. My Hedman short headers are just not suitable for this application though.
That's a lot a upsizing on the jets. I'll bet that equals quite a bit of extra power. I'm waiting to see your drag strip data.

 

To take FULL advantage of your N/A engine you will have to think about intake plenum volume, intake runner length, and head CFM flow (cross sections), camshaft timing, valve sizes, etc., and how they all relate to/effect/work together with the exhaust. Pipemax will lead the way!
Don't wait around for my drag strip data, that's going to be a while. The sooner you get to work, the sooner you can reap the benefits and be well ahead of the learning curve!
Good luck!

 

I cant wait to get this motor done and try to build my system. I really just wanna fabricate the system i drew up and be done with it, but for experimental purposes, that would yeild no good data. SO i think i will install a pair of cutouts and play with collector length.

maybe i'll pick up pipemax

 

This has really turned into an interesting thread. Like I said above there is a lot of untapped power in our exhaust systems. Now how do I tap into it with the stock exhaust routing? That is the question.

 

Your biggest challenge is getting all your perfectly tuned lengths to fit underneath the car without hitting anything and still maintaining adequate ground clearance.
My new challenge, personally, is to quiet mine down with the quietest 3" muff's I can get so I can actually hear myself think. My spintechs are loud cruising around town (at 2500-3000RPM). Prolly some straight through long RV mufflers from magnaflow or something along those lines would bring the sound level down to an acceptable level.
Guess I'm just getting too old, LOL!
I never needed a loud, agressive sounding exhaust...just a good flowing one without all the noise!
leeperryracing has some pics that show a nice factory type routing!
Good job!
https://www.thirdgen.org/forums/exha...dougs-1-a.html

 

Yes, i love his style exhaust. If i am unable to fit a resonator inside my exhaust somewhere, i'll copy his setup and run cutouts

 

I'll leave the resonator box(es) until such time as I've worked out the proper secondary lengths using flanges (insted of cutouts) and extentions.
Instead of LeePerry's setup, I'll use a single 3" or 4" cat back style (with no cat) and keep my relatively quiet Flowmaster in the stock location for daily driving. Something along the lines of DLT504. That keeps things along the stock routing. It just means I'll spend some time prepping the car at the track before I go racing.

 

Looking at another post showing Dyno Don's headers the poster had a tubular K-member. That appears to free up a lot of room so that a terminator box might work for my set up. That way I could have an 18.6" collector on both sides going into terminator boxes.

Like was said above I would need to get the car on a dyno with temporary 18.6" collectors to see if the whole thing would be worth while. Things may not be dead just yet. That VincentZ28 guy is talking about doing some serious head work. May have to do something like this go ahead of him.

 

I spend soem time prepping my car for the track. add skinnies up front, add rear slicks/wheels with spacers, and lower the LCA's, as well as adjust the shocks the proper setting. i wouldnt mind taking off exhaust to run open collectors but i prefer to NOT do that at the track. All my prep is done at my house and i drive to the track, all of 15 min to get there

 

That's the way it'll have to be for me. I drive an hour and a half to go racing. Sometimes towing a trailer if there's a couple of cars going to the track. I take the slicks, tools, compressor, jacks, etc.
It going to be interesting to see what kind of improvement there'll be running and tuning for open headers.

 

Eventually he may have to get on the tuned exhaust band wagon too.
My racing buddy just keeps buying bigger and better parts (deep pockets) but I don't think he's ever had his combination at it's maximum potential ie. headers and exhaust work. Mind you this is a guy who drives his car (67 Chevelle) to the track, bolts on slicks and rips off 11's.
Keep at it and let us know your dyno results.

 

For the time being VincentZ28 has the best times with a 355 in our club. Even though I think I can best him right now. He knows it and is in the process of upgrading his car along with everyone else. Hard to stay in front.

Anyways the tubular K-member has me intriqued with the posibilites. Maybe even a redesign of the headers so that it would be better than shorties. Also to fit in termination boxes.

 

i'm thinking a custom ypipe configuration may be the only way to go with shorties and termination boxes. Because bringing the drivers bank over to the passenger side is making that length soo long while the passenger side is short. putting a box in there will be hard to do either way.

maybe make a large y pipe that goes around the crossmember like DTL504 did

 

I've yet to get my car on the hoist but looking at the different pics I think you're probably right.
How long do you calculate the secondary would be if you went that route?
Does the Pipe Max data allow for an unusually long secondary?

 

eh its hard to say with lookin at the car lol but if you did that kind of exhaust routing and were able to fab a box in there to work ,which still would be difficult to do, i think your collector length would be approaching the mid 20's inches which would tune for a midrange rpm which aint bad, but not optimal if your over 5500 rpms like me or Allen's car

At that point it may be best to shoot for best torque length which is even longer lenght, and make the car a quick 1/8 mile car and sacrifice top end


EDIT; Just checked the numbers Allen gave me, pipemax does allow a longest allowable collector with mufflers, and for my setup thats around 71-73 inches.

Guess where that lies? dumping right before the rear tires! Thats very very doable but i like rear exit exhaust out the bumper

 

Looking at PipeMax it says 73.7" longest recommended with mufflers. 147.4 longest with mufflers. On your motor the data I have given you is the best between 4000 to 6500rpm. That's with the 6000rpm peak horsepower.

For me it looks like I will have to get at tubular K-Member in order to have room for the terminator boxes. That will have to wait until late in the year. In the meantime I'm working on my 4L60E conversion project. Just getting my projects and budget in order.

 

you guys have made me think about my dyno results of my old motor.

when i had it dyno'd before with the HSR and stock tune with some fuel pressure regulator adjustments, i put down 246whp in the summer warm air.

i had my exhaust dumped right over the axle

since then i added tail pipes to exit out the back, probly another 30 inchs of pipe. I then added 1.6 rockers and pullies and put down 252 on stock tune, 254whp with my more timing advance tune in the cooler late fall air, but i was very lean. i think i had 260whp in that setup. Tune was only worth like 2whp but i gained 15lbft torque with the tune

I really wasnt impressed with the 1.6 rockers/pullies gain, 8whp that day but i think it was capable of 14whp with a better tune, but maybe it was because of my increased exhaust with longer pipes making overall collector length longer!

 

There's starting to be quite a pile of data we're collecting. Lots to sort through.
The most interesting bit besides Orr's dyno numbers is the max secondary length of 147". That's over 12'! The next value is around 6'.
I had asked in another thread long ago what the results be if the collectors extended over the axle and into an open case style muffler in the stock location (as duals). Would it be 72" from the header collector flange to a muffler behind the axle?
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[QUOTE=Orr89RocZ;3714466]

I really wasnt impressed with the 1.6 rockers....

Incidentaly, I gained 2 tenths with the 1.6 Pro Magnums. Seems my Vortecs really like them. Little cam too. Only .490 with the change.

 

I'm trying to understand how they figure the lengths. what makes the lengths so critical. Obviously it has something to do with fluid dynamics and wave harmonics but how can 18 inch collector length act the same as a 73inch setup? The only explaination is harmonics of the pressure wave and the length of the pulse. Since its a sine like wave, it will cycle thru its range at different length intervals and i guess 18inch is one, 36 is another for peak torque, and then 73 and 147 is another. This make sense?

For a TPI car peaking at 4500-5000 rpms, a over the axle setup may be of proper length! I dont have pipemax yet so i cant figure that out, but it would be interesting

From my measurements on my car, 72-73 inches is right before the axle. So if you dumped before the axle in front of the rear tires, basically a side exit exhaust almost, you will have 73 inch collectors give or take a few inches depending on how you route the pipes and how far the header comes down under the car

The only reason i feel i wasnt impressed is because my tune was very lean this time around and i added longer exhaust pipes which probly threw things off big time. Given similar test conditions, and equal tune for both 1.5 factory rockers and a tune for the 1.6's, i think the results would have been more conclusive and would have shown larger gains in hp/tq.

 

[QUOTE=Orr89RocZ;3714847]I'm trying to understand how they figure the lengths. what makes the lengths so critical. Obviously it has something to do with fluid dynamics and wave harmonics but how can 18 inch collector length act the same as a 73inch setup? The only explaination is harmonics of the pressure wave and the length of the pulse. Since its a sine like wave, it will cycle thru its range at different length intervals and i guess 18inch is one, 36 is another for peak torque, and then 73 and 147 is another. This make sense?

It's all the post we've read by Urbanhunter. In a nutshell, you're correct. However as you get to the 2nd and 3rd harmonics, that is the second and third most optimum secondary length, the effect is diminished. Still much better than having the wrong length altogether and the valve overlap period is met with the high pressure side of the reflected wave. Then you get into things like gas reversion and the resulting poor volumetric efficiency.
Remember too that muffler design has an impact on how you calculate secondary length. One design of muffler will behave like open atmospere (I believe they call it an open case style) and a straight through muffler (like a glass pack) will behave as an extention of the collector.
So glass packs at the end of the collector with no change in overall pipe diameter will act as one long collector if you dump out right after the muffler.
That's about 72". Hmmm....

 

Thats what i mean, although i LOVE exits out the rear bumper, if i could simulate 2nd harmonic with a dumped before the axle system, that would work great. It will be perfect at 72-73 inches. I'd have plenty of clearance and it be cheaper as it willl have less pipe. Much easier to fabricate

but i reallly dont wanna dump the exhaust under the car... too darn loud

 

I'm going to try and explain this in my own words as simply as I can to help you understand the dynamics behind why and how, but I have no equations to give you to help you figure out the lengths you will need and I do not know how the program calculates optimum lengths.

Best case cenario for exhaust tuning is to try to tune the primary pipe for the 3rd harmonic and the collector/muff/tailpipes for the 4th harmonic. That is why my personal preference is to have a dump of some sort located at the end of the 4th harmonic for the secondary piping, because the 4th harmonic will be too short to squeeze in a muffler/tailpipe (unless the collector IS the muffler).

Indeed, a resonator/termination box of sufficient volume at the location of the 4th harmonic would be ideal, however it would be quite challenging to fit it on the car. Maybe a large 5" or 6" diameter pipe of optimal volume smashed (gently) into an oval for the purpose of ground clearance?

As I understand it, any secondary length beyond the suggested lengths for the 4th harmonic, although they may be tuned lengths, will be a reduction in pulse wave strength, and therefore a reduction in torque and/or the RPM range in which the torque is produced. a longer than recommended secondary= torque production at an rpm that is lower than your engine's optimal rpm range. Shorter = not recommended ( but sometimes higher RPM torque)

Optimum lengths of both intake and exhaust = maximum volumetric efficiency.

The intake runner lengths can be tuned to complement the exhaust and vice versa, but changing intake runner length and cross sections is far more difficult for the average person, so most prefer to deal mainly with the exhaust.

The intake runner lengths on most performance cars are tuned to the 3rd or 4th harmonic. Most single plane manifolds are tuned to the 4th harmonic, but the best case cenario for an all out race car is to tune the intake to the 3rd harmonic, the primary pipes to the 3rd harmonic, and the secondary to the 4th harmonic (if applicable) for the best possible torque curve.

Camshaft overlap comes into play here, because when both valves are simultaneously open, just before the intake cycle, the negative wave created from the tuned exhaust will arrive at the cylinder just as the intake valve is opening, which will cause more fresh charge to be pulled in.(scavenging). If the intake length is tuned properly, the column of air stacked up in the manifold and coming into the cylinder will be timed as well, ADDING that additional charge of air at the precise moment needed to ram the cylinder full before the intake valve closes!(ramming effect).

There are several other factors that play into all of this that I cannot discuss at this time. So, you see, it's the whole "package" that will need to work together as a whole to make the most of tuning.

The more I read up and play with this program, the more I understand...but most times it just raises more questions. It's a constant learning process that never ends.

Hope this answers more questions than it causes you to ask yourself.
-Jesse

 

At this point I think I have a pretty good handle in the science involved and the fabrication required. I enjoy studying the subject and a big thanks for the additional data.
I'll end up with the Pipe Max program eventually. Right now it's time to start assembling the components and building the first iteration of the header back system and then it's to the track and dyno to start gathering data.
It's quite a hobby isn't it?

 

Going through some olds threads and I came across LeePeery's setup. He states a 20+rwhp improvement between his current setup (pictured) and the Edelbrock short header/y pipe arrangement he had previously (like mine currently).
Judging by the pictures I'd say that with those mufflers, the exhaust would react like the secondaries ended at the tail pipes and that is one long collector. From what we've been researching I'd say that although the exhaust is free flowing (undoubtedly attains the 2.2 cfm/hp requirement for minimal backpressure) it isn't designed to take advantage of presurre wave tuning.
What I'm getting at is if LeePerry gets 20 hp by upgrading to a better designed exhaust with LT headers and lots of cfm then we can expect more with the upgrade AND secondary length tuning (whether it's through collector extentions or a terminator box).
Is a 40 hp gain unreasonable?

 

in my post above i'm not sure why i said 2nd harmonic... Pipemax data gives optimum lengths for best hp at my rpm range, but not sure what harmonic its tuning for.

I dont care as long as it works

 

Looking at PipeMax for my car it shows a primary pipe of 21" inches to be right for the 4th harmonic. The 3rd harmonic is 30.2" and is deemed the best by PipeMax.

The collector length is with the 4th harmonic and is 18.3" long. This is the one highly recommended by Pipemax. So 3rd harmonic on the primary and 4th harmonic on the secondary is what Pipemax says is the best. However to fit on my car I would have to stick with the 4th harmonic on both.

This would tune my motor to between 3900 and 6400 rpm with 5900 as the target rpm. This matches my custom intake runners rpm wise. I have them set for a best 3rd harmonic of 5800 rpm but the dyno curve shows the same power points at both 5000rpm and 6400 rpm.

I also just notice that my collector diameter should be 2.914" in diameter. That would be a 3" pipe. Somehow I had thought my 2 3/4" tubing was right on target. I will have to look back into that. I was going to have Dyno Don make me up a set of collector pipes around 18" in diameter for a dyno test to what horsepower gain I would achieve.

 

when do you plan to get back on the dyno?

 

Waiting on Kevin91Z. The next dyno test will be with the catalytic converters tempoarily being replaced by straight tube. Then I would like to bolt on just the collectors and put it on the dyno. By the way I got an interesting reply from Larry Meaux on a question I posed. Here it is.


--------------------------------------------------------------------------------

1989TransAm wrote:
For my set up Pipe Max say to use a collector 2.914" in diameter and 18.3" in length.

The closest pipe would be 3" which is slightly more than recommended. Would one extend the collector length say to 19" to get back in tune? I don't see anyway to enter say a 3" collector diameter into PipeMax to see if the length would change. Thanks for your help.

Also for my setup it says for the primary tube that the 4th harmonic length of 21" is the shortest recommended with a diameter of 1.576". The closest available next larger size would be 1.625". Would one also increase the primary length to make up for the slightly larger size?

Larry's reply:


just "round-off" to the nearest Pipe Diameters
2.914 would be = 3.000"

use a 1.625 Primary

Playing with the Primary Lengths won't be much help,
instead just put the Collector's Length as close as possible
to the Calculated.

i try "unequal" length Primaries/Headers all the time on the Dyno,
and its not a lot of difference on 4-1 Headers,
the Collector Length is all important !

With "Unequal" Length Primaries all i discover on the Dyno
is the Engine just never seems to make the Peak Torque Number
PipeMax says it should....and its not far off, but just not what it could be !

if the Primary Lengths are just about equal length within a few Inches,
the Engines will tend to make the correct amount of Peak TQ.

With 4-1, the Primaries's Diameter is all important,
and the Primary Length is secondary important.

With 4-1, the Collector Length is all important,
and the Collector Diameter is usually secondary .
_________________
Meaux Racing Heads
MaxRace Software
ET_Analyst for DragRacers
www.maxracesoftware.com

Back to top

 

wow 1 5/8 primarys thats interesting. I can see that tho on a 355 but with your heads and rev range i thought a 1 3/4 primary may help top end more.

Hooker longtubes are unequal lengths but i'm not sure how close they are to each other. if its a few inches then i'm looking good for my torque numbers. else its gonna be alittle off but oh well.

If you can get a chance to test full length exhaust with straight cat pipes instead of cats and then collectors at pipemax lengths, that would be AWESOME!

 

That is the plan.

By the way with Pipemax it says your primary tube length can vary from 32.0 inch to 34.5".

 

I saw on the dyno a 20hp gain when I had my 1 3/4 SLP headers with the collector at 2 1/2 modified to 2 3/4 and dual 2 3/4 to 3in cats to a 3in cat back exhaust.

 

Yep, power to be had in the exhaust system. Hey Vincent I see you are keeping an eye on me.

With the open collector experiment I would expect the torque to go up quite abit and the power under the curve to be up everywhere in the power range. I'm not sure how much peak horsepower would go up. I have to find out before I spend money on a tubular K-member and termination boxes.

 

32-34.5 inches will be doable i think. I'm not sure how long the tubes are on the hookers but just buy looking at my engine bay, i could fit that length

another good piece of data showing gains from more flow and proper collector size for the motor. Looks like there is alot to gain on the exhaust side than most ppl realize, including me before starting this thread

 

Playing with my DynoSim program there is a 30 horsepower difference between an open exhaust and a mufflered exhaust. Torque is up to but not as much.

 

Apparently in V 8 applications like ours equal length primary pipe has little effect on peak power because the rpm range over which different lengths come into their own is very broad, as much as 4000rpm.
To quote DV "Most race engines use an rpm band of 3000rpm or less. If the primary pipe scavenging effect overlaps this band, then it matters little the one pipe tunes as much as 1000rpm different from another"
The real focus, and something we can all work on (as opposed to modifying already purchased and installed headers) is attention to the secondary sizing.

 

Good point skinny z, most times the primaries are different lengths and will tune in at slightly different RPMs than each other. I can't remember the exact lengths of the Hooker 2210's, but they were not the 28" that they were advertised as being. MAYBE 28" on the longest pipe INCLUDING the collector. Once the collectors were removed, the primaries were something like 19"-26.5" ranging from shortest to longest. Far from equal length IMHO. And the collector was only around 7"
Maybe I'm just picky, but those primary lengths were too short for my combo and I could not accept it. That is why they were changed to match my RPM range. The wide spread isn't that big a deal, as long as the spread is within your RPM range. The cylinder with the longest pipe will tune in first, and the others will follow one at a time in the order of longest to shortest. As was previously discussed, the secondary (collector) is the more important dimention that is easier to change than the primary, but there is something to getting both primary and secondary to match.
If I had to do it all over again, I'd go with a block hugger header so that the primaries would be closer to equal length, then cut off the collector and add the necessary primary length and a real collector.
Yes! This is a VERY fun hobby!

 

darn, thats alot shorter than i had thought it would be. My optimal is 32-34 Oh well, i hear shorter tunes for higher rpm anyway.

i want a custom setup myself, longtubes with long tubes that tuck up nicely and fit better in our cars. Not concerned with equal length as much as fit/finish/clearance the header gives me

 

WOW! That is good info on the 2210's. Not as desirable as they could be. By squaring them away you made them a little better for that extra horsepower. Like you I think 19" is to short for long tubes.

According to Larry Meaux the diameter of the primary pipe is more important with the length 2nd. With the collector the length is the most import and with diameter being 2nd.

With Pipemax and assuming I have 100% VE with shorty headers I should have a 1 5/8" diameter and between 16.2" and 19.2". I believe that is very doable. Collector length is now 2 3/4" diameter with 18.5" length.

So if my temporary collector works out on the dyno I will have a set of custom headers made up along with the termination boxes.

 

I'm looking forward to the results.
With no ready access to a dyno, I'll do my testing the old fashioned way. At the dragstrip. I'll drop my y-pipe at the track (no cut outs) and tune collector lengths from there. Terminator boxes to follow although I may just sacrifice a high performance daily driver and settle for one tune at the track and another when I'm cruising around. That means I keep a single cat back.
One thing I am doing is installing a wide band O2 sensor and gauge. I believe it'll be a very useful tool when time comes to set up a different carb to go along with the much better exhaust.

 

I had actually posted this on a seperate thread however this seems to be the place to be.
On DTL504's setup,(the good looking exhaust with the cut outs) how effective do you suppose the open cut outs are when the rest of the exhaust system is still attached. Would it behave like an open collector with the associated pressure wave tuning benefit or be less effecient because of the additional exhaust route?
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[quote=Orr89RocZ;3717381]darn, thats alot shorter than i had thought it would be. My optimal is 32-34

What does the data say with respect to the rpm range over which the best primary length operates? Is it very broad, say along the lines of a few thousand rpm or does it tend to spike at a specific point?

 

Pipemax seems to have a range of 2500rpm. When I typed in a peak horsepower of 5900rpm it gave me a range of from 3900-6400rpm.

I would think the cutouts would act like open air. You might have to play with the distance some. I think we are only talking inches or fractions thereoff.

 

I'm going to give this some thought. I'm at the building stage and am leaning towards a removable y-pipe. I can add extentions from there.

 

Is all of this really needed just to make 5-10 more hp in an everyday driven street car? $500 to $800 and the labor may be alot of time wasted. I was told along time ago to work with the stuff already on the car and get the most out of it. It's a lot cheaper!

Allen, tune your car first before you do anything else. I guess the fear of me getting back on the road has gotten you spook.