I have a ZZ4 with AFR 190 heads, Edelbrock RPM manifold and Holley 650dp, Hooker Shorty Style Headers, Turbo 350 tranny with Sat. Night Special TCI converter with a 10bolt with future 3:73. What size ,type of exhaust would be the best for this set-up? The car is lowered with Hotchkis Springs, I know that makes a difference for true duels. I would like to have two 2 1/2" going all the way back and over the rear axle, but if a 3" can do it..also what size y pipes is everyone running?

 

I would go with the Hooker cat-back, there's no need to waste the money on dual exhaust.

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2 Tickets to game= $250
Gas= $20
Sitting 20ft. from MJ= Priceless
'86 IROC T-TOPS, TINTED WINDOWS, BRAKE LIGHT BLACKOUTS
GM GOODWRENCH 350
EDELBROCK HEADERS Hooker CatBack
EDELBROCK 600CFM CARB.
KN AIRFILTER
ACCEL HEI DISTRIBUTOR
160* Stat, just switched to 180* b/c of winter coming and going to college in the mts.
3:73 Posi Rebuilt 700R4
B&M Megashifter, 5" Autometer Tach w/shift lite

 

How do you figure it is a waste of money? My friend went from junk single exhaust to dual 2 1/2 inch and picked up 4 tenths in the 1/8 (8.17 to 7.73)...when i switched from 2 1/2 inch duals to 3" duals i picked up nearly 3 mph in the 1/8 (87.8 to 90.6)....Not to mention the sound is so much meaner and better with duals!!!

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1987 GTA, 355 inch motor, carbureted, TFS twisted wedge heads (non G2), TH400 w/brake, 11.3:1, Lunati hydraulic roller .510/.525 lift 232/242 duration @.050 on a 112* lobe seperation, Hooker super comps, Dual 3" flowmaster 2-chamber exhaust with NO tailpipes, 98 Z-28 wheels, Strange 12-bolt rear w/4.30 gears, 33 spline axles and a spool.

Best ET on street tires, m6, and 10 bolt w/4.56 gears: 12.46@115.1
3515 lbs race weight

Drive it like you stole it!!

Soon to be mods: 10 pt cage, Torque arm, NOS

Hopin for 10's...

 

How much did he pay for the duals, I have heard the fabrication involved is a bit pricey. I don't see how a single 3" can be that much more restricive than 2.25.
And I really doubt that you can knock off .4 just from going from single 3 to dual 2 1/4. There are a lot of factors that come into play. But hey, I'm no expert.

[This message has been edited by Mark A Shields (edited December 11, 2001).]

 

Oh man, now I'm really confused on what to do. How can I run the 2 1/2 pipes, like the way the Y is set up now and run them in the stock location?

 

One pipe off of each header, From factory they Y off just before the Cat, correct? Get rid of the Y, and instead of using single 3", follow the factory routing for Two 2 1/2 inch pipes.

Whether you choose to put tailpipes on the car is up to you. I didnt. You can do it with 2 1/2 inch, but not with 3, it has to be crushed to clear the axle, which totally defeats the purpose of big pipe. Plus, my dual 3 setup is not ran in factory location. Ive got one 3" pipe on either side of the driveshaft back to Two 2 chamber flowmasters, and dumps in front of the rear axle.

The setup cost about 150 for pipe and labor. (2 1/2) Mufflers are to your discretion.

Its harder to find someone that has a 3" bender, Ive found. The duals are definitely worth the small headache involved.

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1987 GTA, 355 inch motor, carbureted, TFS twisted wedge heads (non G2), TH400 w/brake, 11.3:1, Lunati hydraulic roller .510/.525 lift 232/242 duration @.050 on a 112* lobe seperation, Hooker super comps, Dual 3" flowmaster 2-chamber exhaust with NO tailpipes, 98 Z-28 wheels, Strange 12-bolt rear w/4.30 gears, 33 spline axles and a spool.

Best ET on street tires, m6, and 10 bolt w/4.56 gears: 12.46@115.1
3515 lbs race weight

Drive it like you stole it!!

Soon to be mods: 10 pt cage, Torque arm, NOS

Hopin for 10's...

 

First of all, I am no expert on flow dynamics and stuff like that either. But, I do know that the factory exhaust setup on our cars is probably the worst possible design. If our setup wasnt that bad, then why would a car (Corvette TPI vs. F-Body TPI) with the same motor be faster with the only difference being exhaust setup?

Just think about how it has to flow to get to the tailpipes...Exit motor...one pipe goes pretty smoothly into a Y section, while the other has to make just about a 90 degree turn. Then, they both continue in one pipe to the back where they go into a single muffler. One chamber per pipe. One chamber pretty much exits without many bends, while the other does a complete 180 degree turn to get out. Sound like restriction to you?

All I know is that results show stronger than someones flow numbers.

His car DID pick up 4 tenths, went from a 8.20 to 7.73. Actually thats over 4 tenths. Also..The exhaust is 2 and 1/2, not 2 and 1/4.

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1987 GTA, 355 inch motor, carbureted, TFS twisted wedge heads (non G2), TH400 w/brake, 11.3:1, Lunati hydraulic roller .510/.525 lift 232/242 duration @.050 on a 112* lobe seperation, Hooker super comps, Dual 3" flowmaster 2-chamber exhaust with NO tailpipes, 98 Z-28 wheels, Strange 12-bolt rear w/4.30 gears, 33 spline axles and a spool.

Best ET on street tires, m6, and 10 bolt w/4.56 gears: 12.46@115.1
3515 lbs race weight

Drive it like you stole it!!

Soon to be mods: 10 pt cage, Torque arm, NOS

Hopin for 10's...

 

I agree, our stock exhaust sucks. But our cars did not come stock with 3", and you said he went from 3" to duals. I could see knocking off .4 going from factory to duals.

------------------
2 Tickets to game= $250
Gas= $20
Sitting 20ft. from MJ= Priceless
'86 IROC T-TOPS, TINTED WINDOWS, BRAKE LIGHT BLACKOUTS
GM GOODWRENCH 350
EDELBROCK HEADERS Hooker CatBack
EDELBROCK 600CFM CARB.
KN AIRFILTER
ACCEL HEI DISTRIBUTOR
160* Stat, just switched to 180* b/c of winter coming and going to college in the mts.
3:73 Posi Rebuilt 700R4
B&M Megashifter, 5" Autometer Tach w/shift lite

 

So I can run two 2 1/2 pipes in the stock location and run them over the axles on the passenger side? Also how should I run this off the driver's collector? The same way of a bit more straight?

 

My car came with 3" pipe from the factory and it is an 87 GTA. you want to come down and measure it, your more than welcome.
I dont believe in BS so dont quote me to it.

 

yup, run them over on the pass side, run the pipe off the driver collector just like your stock y-pipe runs. Better yet, go with dual 3" setup like mine.

 

Please explain with detail how you did this including what headers you used and how much it cost. Thanks

 

Don't you have to measure the inside diameter of the pipe, wouldn't that be a little hard with the exhaust on the car.

 

Well, quite frankly its really easy to measure when I can go to the garage, and pull out my stock 3" SINGLE pipe. If you read my profile you would see that I run TWO 3" pipes now.

 

I used hooker super comps, bought 3" collectors, bought Two 3" 2 chamber flowmasters.

The pipes come straight back from the collectors into the mufflers, which sit just in front of the rear axle. I ran turn downs after the mufflers.

 

What kind of sound do u want??

FLOWMASTER.

 

Want performance? Don't get Flowmaster

 

You can measure the inside of the pipe for flow calcuation purposes, but all pipe is manufactured, sold, bought, and measured OD.

If you walk into any muffler shop, parts store, or even order from Jeg's or Summit, and you say you want 3" pipe, the pipe they're gonna give you is 3" OD.

Any slip on fitting, whether it be a coupling, elbow, resonator, etc., is gonna be marked 3" ID. That way it slides on to the 3" OD pipe.

I've read so many times on here, people posting that the Dynomax 3" pipe is only 2.75". Well I've asked them was that OD or ID. Only a few answered and said it was 2.75" ID. One guy did say it was 2.75" OD.

Well of course it's gonna be 2.75" ID. Actually if you measure it with a dial caliper, then it'll more than likely read 2.8 - 2.875". That's due to the wall thickness, which is usually 1/16" or .0625".

Although using a bigger diameter pipe, they may use a thicker metal to resist crushing. Then it would be closer to 2.8" ID. But again, that's ID.

If the Dynomax pipe is actually 2.75" OD, then they are guilty of false advertising. That's against the standard that the automotive industry has set.



AJ

 

Gee, sorry , don't take it so personally.