Lets Talk Exhaust for Max power
Thread Starter
Registered User
Joined: Jan 1999
Posts: 989
From: Baton Rouge, la
Lets Talk Exhaust for Max power
Ok, My current setup is hooker LTs with ball flanges going to a mufflex y into the mufflex 4" with spintech muffler. I also have a 4" bullet Muffler in the intermediate pipe. What I have found is when I drop just the spintech muffler(basically dump over the axle) at the track I pick up .2 and 2.5 mph. Now, a buddy of mine runa a true dual 3" into two bullets and dump before the axle. He found on the dyno to pick up 10 rwhp when changing to open headers.
What I was wondering after talking to some dirt track guys is they have found hp by running open headers and collector extensions. They say they put streight pipes on it..run it around for a while to get the exhaust hot, then cut them where the "blueing" stops. They say that is where the find the most power. Anyone know anything about this or tested out different exhaust setups? I'm going for 10s NA from a lt1 headed 355 6 speed and need everthing I can get.
More food for thought. A guy has a 68 Camaro with a 396 LT1 in it. Runs 9.7s NA. His exhaust is hooker LTs into dual 3.5" pipe with borla XR1 race mufflers. He also picked up .1 and 1 mph when he dropped them at the track.
Anyone tried collectory extensions? X-pipes? Tuned the exhaust in any way and found HP?
I don't want to know about cat back systems...I'm going for a high end HP making exhaust system.
Tim
------------------
95 firebird Blueprinted and ballanced 355, ported lt1 heads, custom cam motion solid roller,Moser 9" with 4.57's and a locker just to name a few.
11.23@122.25 1.579 60'
2001 NFRA LT1 NA Winner
More on www.geocities.com/herrint
What I was wondering after talking to some dirt track guys is they have found hp by running open headers and collector extensions. They say they put streight pipes on it..run it around for a while to get the exhaust hot, then cut them where the "blueing" stops. They say that is where the find the most power. Anyone know anything about this or tested out different exhaust setups? I'm going for 10s NA from a lt1 headed 355 6 speed and need everthing I can get.
More food for thought. A guy has a 68 Camaro with a 396 LT1 in it. Runs 9.7s NA. His exhaust is hooker LTs into dual 3.5" pipe with borla XR1 race mufflers. He also picked up .1 and 1 mph when he dropped them at the track.
Anyone tried collectory extensions? X-pipes? Tuned the exhaust in any way and found HP?
I don't want to know about cat back systems...I'm going for a high end HP making exhaust system.
Tim
------------------
95 firebird Blueprinted and ballanced 355, ported lt1 heads, custom cam motion solid roller,Moser 9" with 4.57's and a locker just to name a few.
11.23@122.25 1.579 60'
2001 NFRA LT1 NA Winner
More on www.geocities.com/herrint
Registered User
Joined: Aug 2000
Posts: 504
From: Portland, OR
Long collectors have been around for ever, you can use it to move the torque band up or down. Most tracks have a muffler rule, I use a pair of 4in ID Walker (DynaMax) bullet mufflers 12 in long, use it like a collector and it meets db limit. This is on a old school drag car, injected alky. Go to a nhra division meet and look at the exhuast on stock and super stock cars, it well be pertty much state of the art (with in the rules)
Advanced Tech Moderator
Joined: Aug 2001
Posts: 2,262
From: Nashville
<font face="Verdana, Arial" size="2">Originally posted by 95Bird:
X-pipes? Tuned the exhaust in any way and found HP?</font>
X-pipes? Tuned the exhaust in any way and found HP?</font>
<font face="Verdana, Arial" size="2">Originally posted by Mr. Horsepower
:
Ok guys, as promised in the other thread I have the dyno results from the dual swap. First off, I'm not making any claims as to which exhaust you should run, just giving you the numbers.... so do with them as you see fit.
I would also prefer not getting into the combination as this is not my car. It belongs to a friend. I know a little about the setup but I don't want to turn this into a "What cam is he running" questionathon (my own word there ).
I will tell you this much... the heads are AFR 200's and I did about an hours worth of cleanup/blending on them last year. The cam is a custom ground Isky hydraulic roller and the other mods are as follows...
1.6:1 CC Magnum rockers, TPIS 1-3/4 headers, ported intake, K&N CAI, Granatelli MAF, AS&M 52mm TB, T56 w/LT4 clutch assembly. Oh yeah, it's a 383 running 11.3:1 compression. That's really about all I know other than the fact that I built the exhaust for it.
Ok, this car was running a 4" Mufflex catback and Rich replaced the Flowmaster with a Borla XR-1. Here are the dyno results from last weekend. I had to transfer these from the dyno graph so they aren't 100% accurate... good enough for this comparison though.
2000 rpm 139 rwhp/356 rwtq
2500 rpm 177/365
3000 rpm 226/395
3500 rpm 288/443
4000 rpm 341/459
4500 rpm 388/443
5000 rpm 408/428
5500 rpm 416/405
5600 rpm 418/396 (rwhp peak)
Tonight we tested the duals. This setup uses 3" to 2.5" transitions right off the collector. It then goes into the Dr. Gas x-pipe and then through a chambered muffler similiar to that used in the CMMG catback system. The system then exits at the side ahead of the rear wheel. It's a 2.5" system. There is a noticable tone difference with this setup. The x-pipe also creates a higher pitch exhaust note in comparison to the 'Y' or a straight dual setup.
Anyways, here are the results...
2000 rpm 150/370
2500 rpm 189/383
3000 rpm 236/416
3500 rpm 292/455
4000 rpm 339/458
4500 rpm 385/442
5000 rpm 413/430
5500 rpm 422/412
5600 rpm 426/401
Obviously the x-pipe is making some good torque over the Mufflex up til about 4000 rpm. From there til just past 4500 rpm the "Y" is winning, then the edge goes back to the x-pipe. This is usually typical of an x-pipe dual exhaust unless the situation is compensated for through valve timing. A little less exhaust duration would probably help gain back some of that torque loss in the 3500-4500 rpm range. AFR's generally have good exhaust ports so that only compounds the problem, which I'd conclude is a loss of volumetric efficiency in that rpm range. Maybe a swap to 1.5's on the exhaust would help. Either way, it warrants a little experimentation.
That's a wrap on the test so, considering this combination is pretty much inline with what most of you are doing, you can draw your own conclusions and go from there.
Any questions?
Take care,
Chuck Riddeck
Progressive Race Engine Development
</font>
:
Ok guys, as promised in the other thread I have the dyno results from the dual swap. First off, I'm not making any claims as to which exhaust you should run, just giving you the numbers.... so do with them as you see fit.
I would also prefer not getting into the combination as this is not my car. It belongs to a friend. I know a little about the setup but I don't want to turn this into a "What cam is he running" questionathon (my own word there ).
I will tell you this much... the heads are AFR 200's and I did about an hours worth of cleanup/blending on them last year. The cam is a custom ground Isky hydraulic roller and the other mods are as follows...
1.6:1 CC Magnum rockers, TPIS 1-3/4 headers, ported intake, K&N CAI, Granatelli MAF, AS&M 52mm TB, T56 w/LT4 clutch assembly. Oh yeah, it's a 383 running 11.3:1 compression. That's really about all I know other than the fact that I built the exhaust for it.
Ok, this car was running a 4" Mufflex catback and Rich replaced the Flowmaster with a Borla XR-1. Here are the dyno results from last weekend. I had to transfer these from the dyno graph so they aren't 100% accurate... good enough for this comparison though.
2000 rpm 139 rwhp/356 rwtq
2500 rpm 177/365
3000 rpm 226/395
3500 rpm 288/443
4000 rpm 341/459
4500 rpm 388/443
5000 rpm 408/428
5500 rpm 416/405
5600 rpm 418/396 (rwhp peak)
Tonight we tested the duals. This setup uses 3" to 2.5" transitions right off the collector. It then goes into the Dr. Gas x-pipe and then through a chambered muffler similiar to that used in the CMMG catback system. The system then exits at the side ahead of the rear wheel. It's a 2.5" system. There is a noticable tone difference with this setup. The x-pipe also creates a higher pitch exhaust note in comparison to the 'Y' or a straight dual setup.
Anyways, here are the results...
2000 rpm 150/370
2500 rpm 189/383
3000 rpm 236/416
3500 rpm 292/455
4000 rpm 339/458
4500 rpm 385/442
5000 rpm 413/430
5500 rpm 422/412
5600 rpm 426/401
Obviously the x-pipe is making some good torque over the Mufflex up til about 4000 rpm. From there til just past 4500 rpm the "Y" is winning, then the edge goes back to the x-pipe. This is usually typical of an x-pipe dual exhaust unless the situation is compensated for through valve timing. A little less exhaust duration would probably help gain back some of that torque loss in the 3500-4500 rpm range. AFR's generally have good exhaust ports so that only compounds the problem, which I'd conclude is a loss of volumetric efficiency in that rpm range. Maybe a swap to 1.5's on the exhaust would help. Either way, it warrants a little experimentation.
That's a wrap on the test so, considering this combination is pretty much inline with what most of you are doing, you can draw your own conclusions and go from there.
Any questions?
Take care,
Chuck Riddeck
Progressive Race Engine Development
</font>
------------------
Ken Mook - 97' SS #2544
Advanced Tech Posting Guidelines
- ?rwhp & ?rwtq Naturally Aspirated on the Stock Bottom End.
- Stage 3 Pro Performance Heads, Solid Roller 242/248 Cam, Endur-X Lifters,
- Jet Hot Hooker LTs, True Dual 3" Exhaust with x-pipe, and the list goes on and on...
Thread
Thread Starter
Forum
Replies
Last Post
F'n1996Z28SS
Cars For Sale
8
Aug 23, 2023 11:19 PM
dbusch22
Forced Induction
6
Oct 31, 2016 11:09 AM