Specifically for the turbo, I know the 3" is 58hp for the full system, but what about the 2.5" one?

Thanks!
-Ross

 

Are you SURE they make a 2.5" turbo back exhaust? I'm not aware of one and there website doesn't show one.

 

well no, but the combination of their downpipe/presilencer/catback

 

Dang, what kinda hp can you get from putting a system like that on an NA? Don't mean to steal the thread, just a question.

 

Not as much. Probably 20hp.

 

since the turbo outlet on the stock s5 is only 2.5" in diameter, wouldn't it make sense to stick with a 2.5" exhaust? I don't plan on upgrading the turbo to anything more than a s5 60-1 hybrid. And frankly, a 3" exhaust would be a waste of money for me at this point.

Should i just stick with racingbeat 2.5" components? I already got the dp/ps.

Thanks guys!
-Ross

 

Ya but it will sound bad ***!!

 

Well if you didn't have the 2.5" downpipe I would say get a 3" downpipe at least if you are making everything else 2.5".

On my 87 TII, I have the 80mm (Full RB exhaust) DP, into a 3" cat, into a 3" Borla muffler that splits off into 2 2.5" pipes.

3" is really the most efficient diameter piping for the TII, I would think 2.5" turbo back would still be pretty restrictive (although it wouldn't have any cats...).

 

It is supposedly a 58 hp increase but only if used with a fuel cut defenser and higher boost pressure. The exhaust byitself is not good for that much.

 

is that like a dyno proven HP figure? cause 58 hp is a lot of damn hp for a turbo, or is it just becuase its less restrictive and naturally makes the car run higher boost, and therefore you would need the fuel cut defencer? if this is the case, then i wont go for the RB exhaust, cause any exhaust with the same pipe diameter should do the same.

any nice quiet exhausts out there that still make a decent amount of power? i think im getting to old for very loud cars, lol (im 19) even though loud=fast

 

oh and i know i got an NA but im turboing soon, and looking for a turbo exhaust option

 

RB is the only quiet exhaust.

 

lol RB it is then

but is the only reason it makes that much hp because its less restrictive and ups the boost?

 

Well contrary to what many people beleive the exhaust IS free flowing and straight through. ANY exhaust that is straight through and free flowing will make the boost go up you can't get around that.

 

Is that RB 3" exhaust a "true" 3"? I mean, it doesn't like taper down to 2.5" at the end of the DP does it?

Also, anyone happen to have any sound clips of this 3" exhaust on a turbo?

 

Slap me if this is a dumb question (i'm kinda new), but would you need fuel mods before slapping this exhaust on?

 

On an additional note for original poster, You really cannot have too little backpressure for a turbo engine(power wise). People run open downpipe at the drag strip for this reason. Sound is a more subjective measurement. How much sound is acceptable for what increase in power. The flat out truth is that less backpressure is more power. NA (piston engines at least) need a little backpressure for exhaust scavaging and such, but turbo motors have enough blockage (in the form of a turbo) to have all the backpressure they need, and then some.

GREG

 

The DP and maybe the Pre-silencer are acutally like 3.15" (80mm), and yes after the "Y" pipe is goes to 2.5" into the mufflers.

As for the sounds Trav, imagine you TII stock, with a little more growl, but VERY QWIET at idle.

 

Bump for some more insight
What kind of HP differences are we talking about though?

if the turbo outlet is 2.5", wouldn't that mean that anything bigger would only add turbulence when going to a different size?

 

Bump for some more insight
What kind of HP differences are we talking about though?

if the turbo outlet is 2.5", wouldn't that mean that anything bigger would only add turbulence when going to a different size?

 

someone asked about dyno'd #'s and im pretty sure they have dynoed it and have it available on thier site...
i just got the 3' DP for my TII, and i cant wait to attach it....LOOKS FRIGGIN HUGE!!

 

Knightsports FC605 is quiet.

 

i dynoed my car with and without the rb turbo back, and it did 214 with and 220 without, the dyno is accurate to +/-5 hp so the rb stuff works.

mike

 

It certainly wouldn't be a bad idea. I'm not exactly sure just how far you can string the stock fuel pump and injectors on an FCD, but personally... I wouldn't install more than a cat back and a high flow cat without upgrading the fuel pump and adding some sort of fuel controller first.

Personally, I think the best investment any turbo RX-7 owner can make is to purchase a complete stand alone ECU before they upgrade anything else. But if you don't plan on going any further than what the stock turbo and intercooler can give you then that might almost be a bit of overkill.

 

wait...what? you had 6 MORE ponies with out the exhaust??