[ta man]

Originally Posted by grandville455

11.20's? Y stop there!!! keep tuning that bad mutha lol

What do you think it will run without the 2.5 inch tailpipes??I'm thinking a tenth and 1 mph...more is a bonus..depends on weather conditions...

[ta man]

Just checked the schedule...I'm going on Mopar day! Sounds like fun!

[77 TRASHCAN]

Spank them mopars!

[grandville455]

Originally Posted by ta man

What do you think it will run without the 2.5 inch tailpipes??I'm thinking a tenth and 1 mph...more is a bonus..depends on weather conditions...

It may not pick up anything? lol... the tailpipes mandrel bent or no?

[b-man]

Originally Posted by grandville455

It may not pick up anything? lol... the tailpipes mandrel bent or no?

I would have to agree, might not pick up anything at the track.

I remember reading about Jim Hand testing 3" and 2-1/4" tailpipes on his wagon. Going from his usual 3" tails to some 2-1/4" tails barely slowed the car down. His wagon was making power pretty close to what you're making, he did get it to run in the 11.30s.

[NYGTO]

Enjoying this thread. Part of the reason for limited or no gain might be due to the exhaust gases being cooler when it reaches the tailpipes, requiring less volume than hot exhaust does (although this might pertain more to stock or mildly modified cars). My money is on you guys. Low 11's, 3:08's and great street ability, that's fantastic.

[wheneaglesfly]

Originally Posted by NYGTO

Enjoying this thread. Part of the reason for limited or no gain might be due to the exhaust gases being cooler when it reaches the tailpipes, requiring less volume than hot exhaust does (although this might pertain more to stock or mildly modified cars). My money is on you guys. Low 11's, 3:08's and great street ability, that's fantastic.

If a person had the ambition it would be interesting to see an entire dual exhaust system hand wrapped in Modern Turbo exhaust High Temp Fiberglass wrap.
Then drag strip test.
Just watch for MPH gains & losses.
Its really good stuff.
Started A Ford Single Turbo build 76 mm Turbonetics today.
Engine running the headers were easily 500-550 F under the fiberglass wrap.
I touched several header tubes & never got burnt.
Maybe 130- 140 F on outside of High temp thermal wrap.

[wheneaglesfly]

Not sure if I agree with current exhaust system sizing but everyone seems happy with 2-1/2 Duals.

Bigger is better usually I think but if not turning high rpms it explains why 2-1/2 works.

3-4-5 inch is old school, 3.00" fan here.

Semi trucks running around dual 8.00 " systems...

[ta man]

Originally Posted by grandville455

It may not pick up anything? lol... the tailpipes mandrel bent or no?

Yes they are mandrel bent 2.5 inch PYPES..weather is going to be warmer Saturday then last outing too..so I will have to factor in DA

[Half-Inch Stud]

Originally Posted by ta man

Yes.....mandrel bent 2.5 inch Pypes....

is what i gots. My Summary;

Headers and Collector designs will show Performance deltas.
mufflers also.
Tails at 2.5" mandrel-curved nearly moot and significantly quieting.


Low 11's and 3.08:1 is stunning. I'd be done & re-install the AC system.

[wheneaglesfly]

Post a few charts.
You guys can debate from there.
Big Blocks Love to breathe freely.
Especially Pontiac 400-455 + CI
And Big Block Chevies turning 8,500 RPM @ 1400 HP @ Flywheel.

[wheneaglesfly]

[wheneaglesfly]

[wheneaglesfly]

[wheneaglesfly]

[wheneaglesfly]

[HWYSTR455]

Those charts don't tell the whole story, and are just guidelines. I actually see conflicting info from chart to chart as well.

As gasses cool, they contract, and it's an acceptable practice to use one step smaller tailpipes.

Another factor is bends, as in mandrel vs. compression. And the degree, number, and total distance. You can't compare header mufflers to an exhaust on a school bus.

I know folks that have gone through the trouble to go to 3.5 the whole way out the back, and there was no gain from 3", and the power level was there.

Going 3.5 over the rear and out the back takes some work on almost any body style. That's why many dump out the sides. That's not a good option for a street driven car, as most know.

I'm looking forward to the times of the OP since the tailpipe removal, very curious to see if there was a measurable improvement.

.

[Skip Fix]

So some real track time data on my 78 I posted in the exhaust section thread.

I had 3" H pipe 2 chamber 3" flowmasters and 2.5 mandrel tailpipes omn the car for legal NMCA classes when I ran the RAIV 400. Dropped in the first E head 455 with a 259/262 @ 0.050 solid roller. It would pick up 0.2-3 sec open headers over closed exhaust with mufflers and pipes still on the car. While swapping tranny and convertor noticed mufflers and tailpipes were rusty so pulled the whole system off. Took it to the track and did some tuning. Then add a 3" Dr. GasX and 3" Ultraflows into 3" Torque Tech mandrel tailpipes. Even with the additional weight of the system the car ran identical. 1/8 6.9s @ 99-100 1/4 10.90s @ 123 with that motor.

[77 TRASHCAN]

Low 11's and 3.08:1 is stunning. I'd be done & re-install the AC system.[/QUOTE]

Exactly!

[wheneaglesfly]

Originally Posted by HWYSTR455

Those charts don't tell the whole story, and are just guidelines. I actually see conflicting info from chart to chart as well.

As gasses cool, they contract, and it's an acceptable practice to use one step smaller tailpipes.

Another factor is bends, as in mandrel vs. compression. And the degree, number, and total distance. You can't compare header mufflers to an exhaust on a school bus.

I know folks that have gone through the trouble to go to 3.5 the whole way out the back, and there was no gain from 3", and the power level was there.

Going 3.5 over the rear and out the back takes some work on almost any body style. That's why many dump out the sides. That's not a good option for a street driven car, as most know.

I'm looking forward to the times of the OP since the tailpipe removal, very curious to see if there was a measurable improvement.

.

All are free to decide.

I have chosen.
20 years ago now.
Dual 3.000"

The Hellcats are Real.
10.5 ET with a Good Driver.
New Baseline standard street car fast.

Yeah all will say its just a 13- 11 second car.

The Mother Ficker Hellcat will run with a Veteran pro Driver.
And its on the streets Nationwide.
Looking to street race & claim total domination.