I have the old school hks turbo back exhaust system and it is only 2 3/8" in diameter. I was wondering what a three inch exhaust would do for me considering my mods?? Thanks.

 

anyone?

 

prolly not terribly much. its the fake dual like stock setup? you should go single.

 

2 and 3/8"? That's tiny.. Go for 3"

I think the RB dp is like 3.15" and then you could get the RB silencer or fab a piece of straight pipe to mate up to either a 3" single catback or 2.5" dual catback, whatever.

 

Yeah I need something bigger! I like my car how it is now but with that 3" exhaust I think it would just be that much better. I'm thinking about going single 3" single like you said but why would you go 2.5 if you have duals?

oh and rs1101 yeah they are the fack duals

 

Think about it, 2.5" duals is really 5" in volume if it were a single. If you have a 3" downpipe and your y-pipe has a 3" flange and switches into a 2.5" dual exhaust, you still have more volume after the downpipe. (it doesn't work EXACTLY like that but you get the idea, a dual 2.5" has more volume than a single 3")

This is a very common thing for dual exhausts, the catback is almost always smaller than the downpipe. Like the racing beat unit for example is 3.15" dp to pre-silencer and then the catback is 2 something.

 

the Y-pipe two 2.375-inch (60mm) pipes



Off of RB's site.

I'd say stay Dual. Single isn't nice for a street car. I'd be interested in a dyno of something like a RB 3" to a CS 3". I'm guessing the CS would make a few more ponies at the expense of your ears.

 

Now I could be wrong on this but from turbo applications, the way I see it is a single is best. Reason I say this is because of the vacuum effect of exhaust leaving the system. As the exhaust gas exits the pipe, it also helps pull out whatever other exhaust gas is in the exhaust system. Think of it like syphoning gas out of a fuel tank. The reason the fuel continues to flow out of the tank is due to the pulling force of the fuel flowing out of the hose.

Now with a dual exhaust (or even an extremely large single exhaust, you can get to a point where there is no back pressure from the turbo manifold, its almost like not having an exaust at all. The issue with this would be there is not enough exhaust gas to fill the pipe to create the vacuum effect and just creates a turbulent exhaust flow which can dissrupt the flow of exhaust trying to come out and have a negative effect on performance. Think of the civic guys that have gone out and put large exhausts on their car then dyno'd with lower horsepower than stock. True it could be the richness of the air or temps that day but I think my theory has something to do with it too.

 

The turbo takes care of backpressure. AFAIK its kinda in the way.


This has been debated too much. Just delete your post before it begins again.

 

Mine goes 3" then splits to two 2 1/2", and I'm getting 407 rwhp with my setup.

My problem is that the increasing diameter does little to quiet the exhaust. If you're looking for a really loud setup, use mine. If you like bass, use a big resonator, but this will really decrease your ground clearence. I'll want to dyno test a 3" to two 1.5" in the future, and compare volume vs. power.

Exactly...this is called "exhaust scavenging". There's a fine art to it. If you decease the tailpipe diameter, torque come on in the lower rev areas...to a certain point. Overall horsepower may suffer, but having the torque come on sooner will make up for it on street cars with way too much horsepower already.

 

Have mercy!

 

that looks so badass lmao...

 

damn guys thanks for the info, and green spyder your car is bad ***! Anyways here is my exhaust how shitty is it?

 

Can't really read that.

What size is the downpipe? What size is the catback? Or is it all the same size the whole way through?

 

sorry its got 2-2 3/8, so I'm guessing it's saying that the downpipe is 2 3/8" and the rest is 2". No cats on this just a presilencer.

 

Ah yah that makes sense.

That seems kinda small, I'd definitely upgrade to a 3" system. If you want to go single I'd say full 3" corksport system, cheap, good quality, but will be very loud.

Or a RB 3.15" downpipe/presilencer to CS 3" catback for something a bit quieter.

Or RB full system, the one from the high performance section.

There's lots of options.

 

thanks for the info man! so what kind of differances will I see with a 3" exhaust as far as torq differances hp differances ect... Thanks again dDub

 

Increased boost if you aren't using a boost controller for one. Exact hp and torque numbers are hard to say, but the better the flow the happier your turbo'd vehicle will be

 

I think you'll probably find that means two 2-3/8" rear pipes. 2-3/8" is 60mm, which is the size RB still lists for the rear pipes on their current system, with an 80mm front pipe. A single 2-3/8" front pipe would make little difference over stock. Grab a ruler or tape and go find out for sure.

 

Thanks nz. Now here is where I get stupid Do you measure around the pipe or do I have to unbolt it and measure just the circumferance of the iner circle??? Thanks.

 

Yah that's a good point NZ made. Your catback might be fine the way it is, but if you really wanna check sizes get a piece of string and wrap it around the downpipe, mark the string, take it off and measure the string you've marked this is nor the circumerence of the pipe.

C = pi * D

So divide this number by pi and you have the diameter of your piping for you downpipe. This technically does include the wall thickness of the pipe too but that is so small its negligible.

You can do this for the catback too if you'd reall like. And this is if you really care that much to do so, if you've been looking to change your exhaust anyways well then go right ahead and not worry

 

Just do like I just described. Measure around the outside of the pipe, the thickness of the wall is small enough it wont matter too much. This will give you a good enough idea of the pipe size. If you're going to unbolt it then you can just measure the diameter already instead of doing all this work with the circumference

 

Thanks again Ddub! I'm going to check it now! I've got one question though (don't kill me ) anyways how do I know what downpipe will bolt up to the catback that I have??? Are they all interchangeable??? I thought I read in one of these exhaust threads that they wheren't. Hum..... THis may pose a problem if I just wanted to get a larger downpipe.

 

I have the ss auto crome turbo back system and it is a single that is a true 3.15 inch from the turbo to the muffler where the straight through muffler expands from 3 inch to a 4 inch tip. It was a very good price and the quality seems almost identical to my friend with the racing beat setup. I would look into it if you decide to go single. 230 bucks is all I spent for it.

 

damn thats not bad at all! did you find that on ebay???