exhaust pipping size Options

[maikl]

i have 70' custom exhaust pipping for my beams engine and i've started to wonder if they are too big for my set-up.... ofkorse my car wont stay as it is the aftermarket parts and mods will continues aslong i have my car... do you thing tha an 2,5 inch pipping will better?

[roman]

2.5" or 2.25" will be best....

I know of somone making 270hp at the wheels with a blacktop 3sge, and I dont think that even he runs a 3 inch pipe. 2.75" or 2.5" IIRC!

[maikl]

i dont thing that 2'25 will be ok because beams cames with the 2'25 as stock.... i am noy sure if it worth the money and time spended to cahnge my pipping from 70' to 65... what do you guys thing? i am thinking the futere as well when i am going to change internal parts... i am a litle lost in my mind, can you help me with my dilima?

[doGGy]

one thing - 70 is overkill for sure... 65 as IF it came in stock, is more when enoth, cuz think this way, on stock, you have Catalistic, stock restrictive resonator, and stock restrictive muffler.... as if you gonna do a full 65 exhaust, with full straight through design (free flow res, free flow muffler, and no cat), you will be able to flow a lot more exhaust.. one thing is to be sure - as less curves as posible, cuz one 90' turn is almost the same as 1 meter longer pipe.... So think this way

[Kwanza26]

the size of the pipe doesn't matter as much as a free flowing muffler on an n/a car. Regardless of what the stock specs or whatever are... bigger isn't better with n/a cars. I wouldn't do anything more than 2.25. Hell... even performance V6 exhausts and stuff are only around 2.25-2.5... a 4 banger isn't gonna need it.

[maikl]

so..... the thing now is: will it worth the money and time to change my pippings from 70 to 65? the gain that is.... will it effect the whp of the car? the torque? and if yes in theory how much gain will i get?

[recneps]

the exhaust piping is dependent on a lot of things.

a larger piping size and or more free flowing exhaust will push your peak torque up in RPMs, assuming youve got the cams for it. a smaller and less free flowing exhaust will push your torque band down in the RPMs.

if your peak torque is higher in the RPMs its going to result in more horsepower, this relationship is easy to see with the formula for horsepower.

hp = (peak torque * the rpm you got it at) / 5252

i think 5252 is right.

its up to you if you want nice topend and more horsepower but not so hot bottom end stay 70mm if you want a torque band you can play billards on i would go with something smaller.

so..... the thing now is: will it worth the money and time to change my pippings from 70 to 65? the gain that is.... will it effect the whp of the car? the torque? and if yes in theory how much gain will i get?

you might lose 1-2whp on the dyno by pushing your tq down in the rpm range.

but really that could be dyno error, its not going to be noticible changing 5mm.

[maikl]

thanks recneps that realy helped me alot!