Getting RNR turbo back, 2.5 or 3"????????

[Lordpaxin]

OK, im going to order a RNR turbo back exhaust

do i need the 3 inch, or is the 2.5 sufficient.

my specs are 14b, stock boost, stock fuel, stock spark.

cyclone intake and KN filter, with strait metal intake pipe.

i have heard that bigger exhaust creates compressor surge?

my plans for the future dont exceed a 16g performace range. nothing past 300 - 350HP

what do you guys tinkg?

thanks, later on,
adam

 

[*97GS_Eclipse*]

3 inch. The bigger the better. Of course others will disagree and this will turn into a 3 inch v. 2.5 inch exhaust flame war, but we'll see what happens.



Luke

 

[Lunch_Box]

You could get away with a 2.5" right now but once you start modding your car you are going to want to upgrade to a 3" system. So you might as well do it right the first time.

 

[purplehazetsi]

2.5 inch will be good enough for 300 + hp..... But for the extra 60 bucks, just do a three inch and be a man! Sure its a little louder, but it will be better than going out to spend another 400-500 bucks to get a 3". So save the headace, get a 3" and have fun!

 

[Lordpaxin]

wouldnt 3 inch KILL lowend?

 

[Groomz]

The larger exhaust would not cause compressor surge, but it can cause boost creep. I would say go 3 inch, because you will eventually want to make more power. You could get a 2.5 inch downpipe and a 3 inch catback exhaust, this would help with the boost creep issue.

 

[Lordpaxin]

ok, i just email and chaged up to 3 inch.

is there any other ways to eliminate boost creep?

finding the peak, and setting a boost controller way down?

 

[Trekman8]

Use an 02 housing with an external wastegate dump tube.

 

[Lordpaxin]

but im poor

 

[Trekman8]

do you have acess to or no anyone with a welder? if so you can make one pretty easily by just looking at your stock piece and the external dump ones pictured on the internet. Its only two flanges and two tubes.

 

[Groomz]

Get your factory turbo ported out especially around the wastegate. You can also get a 34mm flapper door for the internal wastegate, which is cheaper than running an external. Wastegates are only necessary if you plan on running lower boost. Replacing the O2 housing with a tubular unit or an Evo III one will help flow as well. Exhaust gases take the path of least resistance, so if you put on that free flowing 3 inch exhaust, it will outflow the factory opening for the wastegate, hence the need to port it out to match the extra flow of the 3 inch.

 

[alex99gst]

Originally posted by Lordpaxin
but im poor

hope you saw this in your search

http://www.rnrracing.com/cgi-bin/cc...=awdo2tbe&cat=exhaust&catstr=HOME:DSM:exhaust

 

[Lordpaxin]

"im poor"


475 / 600

just a lil steep.

 

[2GeNTSi]

I just got my 3" catback installed yesterday, it's a little louder but doesn't sound like crap. Got it off of extremepsi.com, it's mandrel bent, ceramic coated (or it says it is but it just seems like grey paint), stainless steel, good welds, comes with all bolts and gaskets, re-use the bolts on the hangers though. The only probably I had is that you have to have the car really high in order to get it to fit without too much trouble, the muffler has to be perpendicular to the bottom of the car because the bend for the axle is a PITA to fit.

The product is pretty good it's just that the muffler is a 5zigen fireball style, and the description for it said "n1 type" so I expected a n1 style muffler but unfortunately it's not. I noticed today that the piping that goes over is sitting on the chassis and it's heating it up and causing the paint to melt on the outside coat, it's also rattling so I have to fix it. Next year I'm going to get the 3" dp they also make or an Apex'i N1 downpipe that has ceramic coating on it also but I don't think that the N1 dp necks down from 2.5 to 3 at the flex.

 

[Lordpaxin]

any power gain or boost creep?

 

[Libila]

This topic has been beaten to death. It has been proven time and time agian that a 2.5 is perfectly sufficent for a turbo as large as an 18g. A local guy here had a full 2.5 and he was running a 50 trim and he hit an 11, so that says something. People make it sound like back pressure is the enemy, which its not. Some back pressure is good. You dont want to get rid of every little bit because it will kill bottom end.

 

[Lordpaxin]

Originally posted by Libila
This topic has been beaten to death.

So?

i searched, and didnt get my answer.


but i got my answer from this thread, and those posting. thank you all.

 

[Knuckles2.0]

stop standing on your cront clip... its not good for it

 

[Knuckles2.0]

cront= front ..... derp

 

[Lordpaxin]

haha dam!
i thought everyone had forgotten about that

 

[WhipmastaFlex]

where is Doug at? he rocks the 2.5" RnR turbo-back. if you really do not plan on going over a 16g, 2.5" would sufficient. i would recommend a 2.5" downpipe to a 3" cat-back set-up. the only people that NEED a 3" DP are those running a 60-1, FP Red, etc. basically, people running two fuel rails

 

[doug]

Originally posted by WhipmastaFlex
where is Doug at? he rocks the 2.5" RnR turbo-back.

Ah, one of my disciples. Sorry to disappoint you Whipmasta, but I've been out of town. Anyway, yes, I love my 2.5" RnR O2 elim turboback. Lordpaxin, I recommend the O2 elim as an effective way to combat boost creep, no matter which manufacturer you end up going with. It will flow better than even a ported O2 housing. I also read recently that RnR is now using even larger piping on the wastegate dump tubes, which should help even more.

And of course this thread will turn into a 2.5" vs 3" flame war. That is its whole purpose. Why ask the question if you don't want some healthy debate?

J Doug
2.5" is fine

 

[ItsStockOfficer]

OK, Im going to have to make a few points here.

Law of Exhausts 1: For exhaust systems on a turbocharged car, nothing is ever suffcient.

This rule states that no exhaust system can be too large. There is a point of diminishing returns, but it will never become a detriment to producing power. You want to go as large as possible within the constraints of the space/budget you have.

Law of Exhausts 2: You will not lose torque from a larger exhaust system.

This rule states that you cannot loose torque from an exhaust system that is to large. You will only spool faster, hit harder, and create more torque at a lower RPM in addition to more HP at a higher one. This is because back pressure is always much higher then optimum. The same reason a larger turbine housing makes more power, but instead of harming spool, it helps it.

Law of Exhausts 3: Exhausts do not support turbos, they complement them.

This rule states that no exhaust is good up to a certain turbo size, and then larger is nessecary. I have a good friend who ran 12.4@109 on a full stock exhaust, dp, and cat. That DOES NOT mean we all only need stock exhaust systems because they are "sufficient."(Refer to Law 1) He would have been faster on 2.5 and even faster on full 3 inch. A T25 powered car WILL be faster on 3 inch, and as it approaches open atmosphere it will become even faster.

Law of Exhausts 4: Boost creep is a function of flow.

Boost creep is NOT a reason to avoid getting an exhaust, its a reason to GET it. You get boost creep because the new exhaust flows air so well that the wastegate cannot keep it under control. To avoid getting a larger wastegate flapper by sticking with smaller exhaust is like only boosting 14 psi so you don't need to get a fuel pump. Your purposely limiting the power/spool of the vehicle your trying to make fast. Stupid.

 

[Libila]

Originally posted by ItsStockOfficer
Law of Exhausts 2: You will not lose torque from a larger exhaust system.

This rule states that you cannot loose torque from an exhaust system that is to large. You will only spool faster, hit harder, and create more torque at a lower RPM in addition to more HP at a higher one. This is because back pressure is always much higher then optimum. The same reason a larger turbine housing makes more power, but instead of harming spool, it helps it.

Yea ok

 

[ItsStockOfficer]

Its true, deal with it. I know your grandpa told you differently.