Right now i have a 3 inch Borla cat-back on my IROC. I'm putting a alot beefier engine in my car, a 383 that should run 7.0's in the 1/8th mile (4-bolt main 350 block, AFR 210cc, Edelbrock single plain manifold, Demon 750cfm carb, 10.5:1 compression, both my cousin and his best friend have this exact motor in there 3000lb cars and they are running 6.5's and 6.7's, With my car being 3500lbs i figure it'll do 7.0's, anyways....) I want to upgrade my exhaust so i dont limit myself. I will have Hooker LT's and Mufflex Ypipe as well.

Now with a 4inch mufflex cat back, they sell a single outlet exhaust, and a dual outlet, does the single outlet flow better since its straight through rather than splitting into two? Thanks, Mike

 

Yes the single in single out flows better than the cross flow style.You should check out magnaflows new catback for f/bodies,it not 4in but it will give you an idea on how to have split exit with out a cross flow muffler

 

Why spend the money to get nothing out of it? Keep your Borla. You don't need that big of exhaust for the times you are going to run.

Just IMHO

 

unless your over 400 horse it won't help. i have a custom 4" setup with single out spintech and love it.

good luck.

 

RobsWS6, Read alittle harder into my post buddy, the motor i'm building puts down between 550-600hp, which is just a little over 400hp.. Like i said, the same exact motor is in my cousins car (73 Nova) and one of our friends cars (67 Nova, both race cars) and they are going 6.5-6.7's in the 1/8, and 10.5-10.7 in the 1/4. And for your next question, yes i am building my IROC into a street/strip car which is the purpose for the exhaust, to be street legal (somewhat)

Well anyways thanks for answering my question, I have decided to go with the single out 4" Mufflex..

Mike

 

out of curiosity what cam are you using and what are the specs on it. I am planning a similar build just probably with afr 195's and a mini-ram.

 

I do not have the exact specs of the cam, i have to call my cousin to get them, if u are seriously interested i can post the specs at a little bit later time, however i am using a carberator, not fuel injection, Carb'd motors like different style cams, FYI..

This is the engine build-up:

350 4 bolt main block, , .030 over bore, zero decked block
AFR 210cc heads 2.08/1.60 vavles w/ competition port
Lunati Forged rotating assembly (10.56:1 compression)
Solid Cam (.6xx/.6xx lift) (i will find out exactly)
Edelbrock Victor Jr. single plain manifold
750cfm Demon carberator
Hooker Long Tube headers

Friends ride: 67 Nova, same motor with 11:1 compression runs 6.5x 1/8th mile, 10.5x 1/4 mile

Cousins ride: 73 Nova, same motor with 10.25:1 compression (the shop that did his block didn't zero deck the block so he ended up with slightly less compression) runs 6.7x 1/8th mile, 10.7x 1/4 mile

Thats the jist of it all.. Any other questions, i'd be happy to reply..

Mike

 

I did read it and I'll still stand by what I said. For the amount of money, it isn't worth the gain.

I ran 12.1x with the stock 2.75" cat-back. I've gone 121.xx mph so far on the 3" SLP. Could be even more if I could launch with some boost. There is easily .5 sec left in my combo with a decent launch. I know quite a few guys with cars that run in the 10's with just a 3" exhaust.

Good luck

 

i would still be interested in the specs of the cam and thats good info i only really know stuff that applies to my own car so i didnt know carbs like different cams. I also want to know what kind of hp your expecting? My car is going to have a mini ram so it should flow close to if not better then a carb and im going with a slightly smaller head so its a cool comparison plus im always wondering what people are running

 

I dont know the exact hp numbers but if i were gonna guess it would be around 550-600hp, both cars that the motor exsits in right now run 10.5-10.6 in the 1/4 mile, my cousin did the math and came up with 610hp but thats just theoretical due to a mathmatical equation.

And just for your information, dont go by what magazines say all the time, i know in TPIS they say the mini-ram will run faster then a carb, well its not true, put a single plain manifold and a carb on a car and u will be faster anyday of the week, although i must say it is alot cooler to look under the hood and see fuel injection. Having the Mini-ram will make your car more efficient but not faster. When your talking high hp engines, once u hit about 500-600 hp the mini-ram will be pushing its limits. If u look at the LT1 section Jason Short started a thread on a 4 barrel single plain injection setup that out does the LT1 intake however it is still compatible with the engine and computer, if the 3 inch runner injection setup (Mini-Ram, LT1 intake) is "better" than a carb than why would they be changing to a carb style setup?

Thats all the info u get out of me today, i'm tired, Mike

 

see thats the thing..he isnt running boost...NA motors need more "room" because the gases or intake isnt being forced...

you could run 10's with a boosted tpi...but no were near that NA...
for 600 ponies..id be all over that 4 inch...hell im "only" making 475 and im quite happy with the 4 inch pipe with dual 3 inch tips...

looks pretty badass to

 

Ahhh dont throw my plans out of whack.....i know what i want parts wise although im not sure what hp its going to make and id be pissed if i spent over a grand on a mini-ram and it couldnt keep up with the rest of the engine!