oneoverwrx

iTrader: (1)

I am building an ls1 240sx. It will be n/a with a trex cam for now, might hit it with a small shot if im close to doing something cool but i doubt it. I am going to be using hinson longtubes that have 3'' exits. I was planning on doing a y pipe with the 3s going into a single 3.5 all the way out. I know the 3.5 would be a little over kill for now but on my next setup i am planning an lq4 based stroker with a blower and will probably need it.

Will i hurt the power of the current setup by going that big right now?

Whats the best set up for the power i am going to have this time around(450ish)?

What will be good for an f1 later?

I am more concerned with the current set up cause if i like it i may never change it, but i would like the ability to build a 3.5'' exhaust if it isnt going to hurt me to bad now. On another note, a 3in 3 out y pipe can be made much cheaper and a 3 inch exhaust can be bought for cheap...so i might be better to just do 3 now and change it later?????


Thanks a ton guys!

oneoverwrx

iTrader: (1)

WOW.

come on guys.

I have never in my life had an n/a car and i have heard there is a certain amount of back pressure that can help and etc. Harmonics and exhaust pulses?????

Or does it not matter, would open headers net the best overall gains. If so i can figure it out from there. I just didnt know many people other than 240sx guys running a single exit.

Nissan LS240

iTrader: (1)

why not run dual, if you are trying to keep it stock looking, i ran both tips to the same side, here's a pic



the only problem that i think you might have running duals, is I put the mufflers where the fuel tank was, I'm about to dyno the car with full exhaust and with just open headers, trying to see if installing cut outs is worth it, but got to fix my broken clutch first, so i pass along that info if you want, my sig, has what's in my 240.

oneoverwrx

iTrader: (1)

well the obvious things are cost and weight. Really needing to hear about harmonics of a y pipe. Probably going to do a 3 inch y and a 3 inch catback.

Verz

iTrader: (21)

IMO a 3.5 will be a good size for the setup you have initially planned, if you can have a custom y built with a good flowing merge like the flowmaster or qtp merge and the like than a single 3.5 will save you weight and space over duals.

https://ls1tech.com/forums/7248595-post9.html
https://ls1tech.com/forums/2987587-post19.html

According to that last link 450rwhp w/ 15% drivetrain loss should equate to 529hp at the crank which puts you in the range for a 3.5 exhaust. This is all what ive gotten from this site so if im wrong others please feel free to correct me.

oneoverwrx

iTrader: (1)

really appreciate the links and info!!!!

blkjck

is it a s13 or 14? isis makes a 3" straight piped catback id think 3" is enough if you run good headers and Y pipe

91 240

iTrader: (6)

if you're looking for a catback exhaust, check out the Apexi GT Spec. It's 3.75 and all one piece.

Here's one seller that is awesome to work with.
http://www.enjukuracing.com/apexi-sp...sx-p-7232.html

oneoverwrx

iTrader: (1)

that apexi is a nice piece but 675 for a catback. LOL

Found me a flowmaster y collector and have that on the way. going to do a custom 3.5 to a super sweet ricer can!!!

Verz

iTrader: (21)

Thatll be super loud, might have a bullet added before that or possibly some 3in bullets in the y pipe unless you want it loud than go for it

speedtigger

iTrader: (16)

The calculator says that 3.5" has a 9.61" cross section area. (Pi * R squared) This is slightly less the equivalent of dual 2.5s which has an cross sectional area of 9.81. However, there will be less wall friction so I would consider a single 3.5" pipe equal in flow to 2.5" duals.

As for pulse waves, I would not worry about it too much unless you are trying to extract every last pony. If you are that person, most dyno tuning experts will recommend a break out box 18" past your header collectors. This will create a tuned wave termination point for your headers similar to open exhaust with an 18" collector extension which racers generally claim to be ideal. You could use these for your break out box: http://www.flowmastermufflers.com/sh...=&orig=9430109
Or, you could build some.

brian_rs/ss

i have a 4" set up and it performs great. i love it.

vids in sig.