djtimodj

Guys need some help on an exhaust idea Im looking at.

Currently trying to lighten the car as much as possible and I can save weight and possibly make more power by swapping out my current exhaust system for a new single.

My current set up is APS 3.5" downpipes into a dual 2.5" custom system that uses 5zigen rear boxes (only really small resonators tbf)

I am looking at a custom Y Pipe 3" with each bank inlets into a 3.5/4" outlet that feeds a 3.5/4" single exit with a small rear silencer.

Any one have a similar set up? Or run a standard 3" system? Do you think I will lose or gain power switching to this??

dikspiel

iTrader: (70)

If you want to save weight on the exhaust, get a titanium exhaust. I wouldn't have anything less than 2.5" true dual on a TT car.

bealljk

iTrader: (13)

DJ - what are your power goals? or what are you making now?

I'm on this same 'task' right now...trying to reduce weight and I have totally over looked my stillen true dual exhaust.

Theres a really good section in chapter 11 of Maximum Boost about engine power to exhaust sizing - bigger isnt always better. If you need a screen shot of it let me know.

djtimodj

Im at 470whp at the moment. Want to push boost up another 7-8psi next year tho.

Dik i would love a ti exhaust but its just soooooo expensive!! Not an option.

Bea if you can link me with that info that would be amazing.

bealljk

iTrader: (13)

remember your x-axis is bhp, not whp...but if at 600bhp then approximately a 2.67" exhaust is your target...maybe you go 3" ...

do yourself a favor and go get Maximum Boost (by Corky Bell) it's packed full of information like this and it's a good technical read.

Resmarted

iTrader: (2)

Just get a 3". You could go with a tomei, it's close to 3.1 ID.

3" can flow for days provided it's a well designed piece. A 3.5" will get you to 7-800whp easily. People run 3" on supras well over 600whp. Some people even go up to 700 800 at the wheels on a 3". Gas doesn't care what engine it's coming out of. It's just physics.

Dual 2.5" ID is huge. Like overkill actually.

4" is more about looking cool (just like dual 2.5"). It can flow so much, it will make your head spin.

Just make sure you have a true 3" ID exhaust.

Don't make your exhaust out of aluminum... It will eventually blow out with some backfiring.

djtimodj

Thanks for the reply.

I have looked at tomie ti exhaust. Looks to hang down low under the car which os not ideal but cheap for a ti exhaust.

I know cars can make power with smaller exhausts but why do people run dual 3" systems then and get gains?? I cant get anymore boost on my current set up due to soft aps TT springs so was hoping a larger flowing exhaust may help with the benefit of dropping a few kg down in weight too.

dikspiel

iTrader: (70)

I don't know what Resmarted is talking about, if you are running true dual 3" you would make more power vs 2.5" true dual on a twin turbo setup.

Highway Riding

iTrader: (6)

Bigger and less restrictive is always better for flow on a turbo machine.

Resmarted

iTrader: (2)

I'm talking about **** that isn't regurgitated like aids in the scrub *** 350z communities.

Technically you'll probably flow the best with open down pipe, but it's not like you can't make power on a 3".

People have pushed 3" well into the 700whp range on several different platforms.

Can you/will you make more power with more exhaust? Depends.

If you're at 500whp, not that much. Depends on a lot.

I'm just saying you don't need to go overkill to have enough exhaust. There are a few cars that have lost power.


3" would be fine. You might make more on 3.5" depending, but 4" really isn't needed until some crazy power levels.

I mean his car traps 119. That's not a **** ton of power to need 4" exhaust ffs.

dikspiel

iTrader: (70)

chill out

ge35es

less diameter = less weight
a 3" diameter system is more than enough for FI. The true test is measuring the back pressure at peak HP. That is obviously Corkeys book... he talks about back pressure vs intake pressure and what ratios to look for.

bealljk

iTrader: (13)

Technically, you're right...

As long as the ratio is zero then you are correct...

Resmarted

iTrader: (2)

Dog, why don't you fight me

This site is so boring now. Nobody fights with anyone

dikspiel

iTrader: (70)

You see how much I post now, I don't have the energy to argue.

rcdash

iTrader: (18)

The vacuum actuated butterfly valves now available on eBay for under $150 provide so many more exhaust options. We are no longer limited to SP's ridiculous $500 boost actuated valve! I have two 2.5" valves right before a G37 muffler, triggered by TPS and boost to open providing an exhaust path around the the restrictive muffler. Sounds great at WOT, quiet around town, and optimizes performance.

Resmarted

iTrader: (2)

I'm going to send you some non fda regulated pre work out with meth and test so you can dose up before you post brah

Justin100

cut a hole in each side skirt, put a 3.5 inch downpipe sticking out on each side below the front fenders.

and get a bee R rev limiter and go to a garage and just 2 step and destroy everybodys ears.

put 2 mufflers in back hanging so police think you actually have mufflers on your car.

tell your tuner, you refuse to pay him until your car sounds like this.



hehehehehe >=^)

terrasmak

iTrader: (8)

Great reading, I guess my 3 inch Motordyne single should be find for my build

ogiehooker

LOL!!