Light Exhaust Or Big Exhaust?

[Kaido]

Hi all,

I have an S14 with RB25DET swap. While I love the motor, it really has added alot of weight to my car. Exhaust wise, I was considering getting the Greddy 80mm full titanium exhaust (save about 25-30 pounds), or try to find a bigger diameter exhaust. The biggest one I could find so far was the Apex-i GT-Spec which has piping that goes from 75mm to 95mm and a 115mm tip. So what's more important, size or weight?

[siddr20]

To me the noise it produces is the most important!!

you dont want some big ass exhaust being so loud that it wakes up everyone 2 blocks away.. or sounding like it drones..

Trust me the noise will get to you after a while..

I say just get a simple light weight one with a bit of grunt in it..

I like my exhaust:

Think its a hks twin pipe design, but it sounds bloddy nice.. when i pull up to the lights i had a few ppl saying they like the sound of my exhaust!!

Edited March 22, 2007 by siddr20

[ProphetR33]

Hi all,

I have an S14 with RB25DET swap. While I love the motor, it really has added alot of weight to my car. Exhaust wise, I was considering getting the Greddy 80mm full titanium exhaust (save about 25-30 pounds), or try to find a bigger diameter exhaust. The biggest one I could find so far was the Apex-i GT-Spec which has piping that goes from 75mm to 95mm and a 115mm tip. So what's more important, size or weight?

Once you start going into the realm of over 3inches the gains are minimal if anything at all. And possibly losing low down torque due to lower back pressure.

Go a 3 inch system thats lighter. That'll reap the best rewards.

[DECIM8]

ive got a 3 inch front-twin dumps 5" high flow and 4" cat back 4.5" tip ..

Sounds mint .. But any bigger and you start losing back flow and that loses power I think 115mm tip is insane really lol but hey depends the noise you want to make .. I know I turn heads when im driving ... but 4th gear top of the pedal its 100% silent .. pretty good for cops .. until you stop!

[MANWHORE]

Noise is personal preference. I'm running 3.5" straight pipe pretty much, metal highflow cat, 3" split dump/front.

I dont' find it overly loud at all. I actually wish it was a bit louder.

[Pauly33GTS-t]

just get that burble coming out the other end that everyone likes, achievable with a full 3 or 3.5 inch exhaust. I've got a rather nice burble with 3 inch dump, magnaflow cat, and a 3.25 inch 5zigen cat back zorst with a quiet jasma cannon that still roars when throttle is opened up.

[Ronin 09]

Once you start going into the realm of over 3inches the gains are minimal if anything at all. And possibly losing low down torque due to lower back pressure.

Go a 3 inch system thats lighter. That'll reap the best rewards.

WTF is with people continually talking about "less back pressure" and "losing low down torque" on turbo motors with big exhausts??

This is simply untrue.

The exhaust wheel is more resistance and will be the limiter of "back pressure" on the head, the exhaust will not affect back pressure at the head.

On a turbo car the bigger the exhaust the better (within reason).

In answer to your question - different material exhausts sound different. as a general rule, if you keep the design of the exhaust the same, ie same diameter, same number of like resonnators etc,

1. titanium will be raspy and loud

2. stainless will be resonnant and mid volume

3. mild steel will be bassy and boom more

this is merely because the heavier material will damp the volume and affect the resonnace within the exhaust pipe itself.

[Pauly33GTS-t]

makes perfect sense...

[STATUS]

HMMM titanium..... i run the new 5.2kg (instead of 16.5kg) GREDDY 80mm (90mm is an option) PEtir on cats RB26 powered s13 now.... so sexual.

Edited March 22, 2007 by URAS

[2BNVS]

lol back pressure.... Ronin_09 reply was exactly how i would have replied i got a 4" straight through stainless seems very good for me down low, although im used to slightly louder exhausts it doesnt really bother me

ben...

[Munkyb0y]

Ronin is right. so is 2BNVS. lol.

mandrel bend is the way to go. all these twists and turns add the equivalent of metres to your exhaust.

mine is practically straight thru with minimal bends.

[ProphetR33]

WTF is with people continually talking about "less back pressure" and "losing low down torque" on turbo motors with big exhausts??

This is simply untrue.

The exhaust wheel is more resistance and will be the limiter of "back pressure" on the head, the exhaust will not affect back pressure at the head.

On a turbo car the bigger the exhaust the better (within reason).

In answer to your question - different material exhausts sound different. as a general rule, if you keep the design of the exhaust the same, ie same diameter, same number of like resonnators etc,

1. titanium will be raspy and loud

2. stainless will be resonnant and mid volume

3. mild steel will be bassy and boom more

this is merely because the heavier material will damp the volume and affect the resonnace within the exhaust pipe itself.

Fair enough, I've always been told that, so I assumed it was true.

Always happy to be corrected though, thanks for clearing that up.

[Sydneykid]

My 20 cents;

80 mm is plenty big enough for 400+ rwkw

Titanium is light

Go for it

cheers

[R31Nismoid]

Hi all,

I have an S14 with RB25DET swap. While I love the motor, it really has added alot of weight to my car. Exhaust wise, I was considering getting the Greddy 80mm full titanium exhaust (save about 25-30 pounds), or try to find a bigger diameter exhaust. The biggest one I could find so far was the Apex-i GT-Spec which has piping that goes from 75mm to 95mm and a 115mm tip. So what's more important, size or weight?

Whats the spec of the car?

Power aim? Turbo? etc etc.

3" is "just" good enough for 300rwkw ideally you want 3.5" min... Much over you really need to head to 3.5" or 4"

So once we know what spec/power you want, then you can choose the size

[Wheezy]

If its in a silvia go a side pipe...cant remember if the rails on the car are like an S13 but ya know you wanna

Be a man!!! Do ittttt

Nah I agree, power level aims play the biggest part (and stainless is the most logical answer for a poor ass jap car owner) sounds reasonlable too!

[STATUS]

Whats the spec of the car?

Power aim? Turbo? etc etc.

3" is "just" good enough for 300rwkw ideally you want 3.5" min... Much over you really need to head to 3.5" or 4"

So once we know what spec/power you want, then you can choose the size

yeah its funny how many orders i get for skyline owners who seem to believe they "NEED" the 90mm and 94mm systems...... i ask what mods and most dont even have turbo upgrades..... worst thing is they believe best and questioning them enrages them further... oh well.

so yeah 80mm FTW

and 90mm for those who know better.... or something

[Wheezy]

I know why trent...Its cous ben ellis said so in his latest edition of hpi............or something

[Kaido]

Whats the spec of the car?

Power aim? Turbo? etc etc.

3" is "just" good enough for 300rwkw ideally you want 3.5" min... Much over you really need to head to 3.5" or 4"

So once we know what spec/power you want, then you can choose the size

Well, it's a 1998 240sx with a Series 1 RB25. My plans are a 6boost manifold and a 600hp GT3040r .82ar turbo (I believe it's the one you had) topping out around 450-480rwhp ideally, with of course supporting internals/fuel and all that good stuff. The whole "backpressure" myth is still going strong here in the US, mostly because of Honda kids, but no one here has the experience with RB's that you folks have. I don't know how much a Skyline GTS-t weighs, but my car without me in it is around 3100lbs now compared to the ~2900 it used to be with stock motor. Needless to say I've really felt the difference in the front weight and have been working on ways to lighten the car and improve balance (remove sunroof, CF hood, battery relocation, etc). My eventual goal is road racing and the dragstip.

Another thing I considered, is that with the 3.5"+ exhaust I would have to find a 3.5" downpipe and cat or test pipe, so that there won't be any restrictions.

[R31Nismoid]

Your after something thats 3.5" then dude IMO from what i saw with mine.

3" will *get you by*... but ideally for that its 3.5" and it would be spot on the money

[Kaido]

If its in a silvia go a side pipe...cant remember if the rails on the car are like an S13 but ya know you wanna

Be a man!!! Do ittttt

Haha my car is already a huge cop magnet, so as cool as a side pipe would be I couldn't afford the legal problems.