im running a 355 with 1 5/8 headers, 2.5 in y pipe and 3 in the rest of the way. someone told me yesterday if i weld in a 6 in long section or 2 in pipe at the back of the y id see my torque curve jump up quite a bit. it sounds legit but im looking for other opinions

 

I would stop listening to that "someone" and do more research here regarding exhaust, etc.

CG

 

so you dont think that its too open then?

 

Old wives tale!! Backpressure is only used on 2 strokes to prevent over scavenging from pulling too much air/fuel out into the exhaust.

 

^ Wurd....

 

since you changed your exhaust, what kind if difference have you experienced? Did you lose low end torque? when i first bought my car it had no catback, just a dual ypipe. After i added a 2 1/4 catback and muffler the car performed totally different. It had a lot of low end torque. Without my catback it felt like it made more power in the higher rpm's, but definately less low end

 

I mean 3" sounds a little big for what you are running. If your only mods are headers. I think you may benefit from that big of an exhaust after heads and intake swap.

 

I don't know how many people I've tried explaining this to. A loss or gain in torque or throttle response is not due to enough/too much backpressure. It's exhaust gas velocity. Too big and you'll slow down the flow, making the car feel laggy, and underpowered down low. Too small, you'll have excellent response since the gasses have no room to expand and cool, but not enough flow for up top in the RPM range.

This someone's thinking is odd. Back pressure kills power.

 

Are you even running a muffler?

 

Good question.

 

im runnin a hooker aerochamber. also for further info, its got a comp extreme energy cam, fuelie heads and a full msd ignition. all my power is made up top anyways. it had a similar exaust setup when i bought the car, tho so idk what it felt like from stock to this. old system rusted out, only differance is the old headers had air tubes and the new ones have a slightly larger collector.

 

You will just be creating a choke-point if you follow that "someone's" advice. A 2 1/2 to 3 inch exhaust is totally fine for your application with the mods listed above, provided the combo works and has a good tune.

 

I agree, with a carb car, play with your timing and fuel to get it where you like it performing.

 

yeah thats where im at now. i been screwin with it for weeks and i cant get it right. i gotta throw in the new fuel pump i bought and im takin it to a dyno shop. edelbrock 1, racca 0 lol