skinny z

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.

DTL504

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.

skinny z

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.

skinny z

[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?

always tinkerin

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

skinny z

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.

always tinkerin

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

skinny z

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.

always tinkerin

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!

Orr89RocZ

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

1989GTATransAm

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.

always tinkerin

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!
http://www.thirdgen.org/techboard/ex...dougs-1-a.html (pics of my dougs 1 3/4 LTs and X-pipe true duals!!)

Orr89RocZ

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

skinny z

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.

1989GTATransAm

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.

Orr89RocZ

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

skinny z

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.

skinny z

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.

1989GTATransAm

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.

Orr89RocZ

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

skinny z

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?

Orr89RocZ

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

1989GTATransAm

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.

Orr89RocZ

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!

skinny z

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.