On a stock internals motor, an exotic header and 2.5" exhaust ain't gonna make much of a difference over a pretty standard assortment of parts. The "regular" stuff is pretty capable of flowing up to the needs presented by the motor.

However, when you start getting into the motor, freeing up the exhaust alone can yield another 5 to 15 hp depending on what exactly is done to the motor and how much you free up the exhaust.

 

Tell that to GK and Austin. No internally stock ITR's that I'm aware of are pushing just shy of 200 WHP with off-the-shelf headers and <2.5" "commercial" exhausts.

 

Generally, MFB is right, it wont make a huge difference, but there are exceptions. I think he was speaking in general terms.

We have seen some of SMSP and Hytechs offerings make 15-20+whp additions on otherwise stock motors. If youre going NA, youre going to need every bit of help you can get to make power. Header/cat/exhaust has gotta go.

 

I have to agree with Padawan and Nick. Although you can do things on a budget you get what you pay for. At the very least I would buy a OEM JDM 4-1 (2.5" collector). The 2.5" collector is known to make more power and will set you up for cams in the future. If you are willing to spend the money a Toda/SMSP has been seen to make 10-12 hp on a stock ITR motor. My car baselines 164 whp on a dynojet. I have a Comptech Icebox/Toda Header/Comptech exhaust and tuned (Using power FC and Hondata: I have both to play with) I make 185 whp. Thats 21 whp from i/h/e and tuning. I should be able to make a bit more with a few changes as some more tuning. GK is making 190+ on stock cams as well with top end parts.

Remember these are Type-Rs so the comparison engine to engine is off but the illustration that bolt on's don't do anything is a bit off.

In fact we had a 2000 Civic SI that was making 141 whp with AEM/DC Sports Header (2.25" collector) and Greddy SP tuned with VAFC. We swapped in the JDM 4-1 and tuned a bit more with the VAFC and walked away with a lot more midrange and 151.x whp. Now some of this was tuning but the header alone provided that need to tune and we saw a 10 whp gain on a 1.6l

Just some examples. You can get a DC sports JDM 4-1 for almost as cheap as other basic header setups. Choose your parts wisely or you will be down on potential power or spending more money in the long run to replace the bottlenacks. You can do it cheaper but replacing cheaper parts that don't perform will cost you (buying used is always a good idea too).

 

Generally speaking since we're in regular Integra land, I mean a GSR or less. Not an ITR.

I don't disagree that a 2.5" header is a good idea, however on a totally stock GSR, Si, plain B18B Integra, whatever, it might not necessarily produce much of an increase without tuning.

Not disputing Trey's dyno results of course, but most of the gains I've seen with 2.5" headers are on ITR motors or lesser ones with internal mods that bring them at least to that level.

And of course, the part of my post which you so conviniently left out of your quote, that in fact qualified my first sentence with essentially the same thing that you decided to point out, is as follows:

Stop trying to find every opportunity to contradict me. If you have some sort of issues you need to work out, contact me via PM or email.

 

We ITR owners have to be careful relating our experiences and correlating them with other B18 motors because, although I'm sure Integra owners are tired of hearing about this, our motors are different from regular B18 motors.

Our heads flow differently and our cranks and pistons are different, aren't they?

This is the very first dyno on my ITR motor. A rolling Dynojet that was at VIR. The motor didn't have a lot of miles on it.


Here is a dyno plot that compares two versions of my ITR configuration. The lower numbers are with a Comptech Icebox, SMS header, Carsound cat and SMS 2.5" exhaust all the way back.

The higher numbers add very mild head work and a cheap Hondata tuned for track use.


This is the kind of experience that ITR people have when dealing with our motors, but it doesn't mean that we all necessarily know what we're talking about w/other B18 motors. I have owned a GS-R, but never modified it.

I'm only posting this to show what the ITR owners are talking about, and I have to give way to the knowledge exhibited by people who have modified non-ITR B motors.

 

Before people rag on the low original dyno numbers, please remember that ITR motors have never dyno'd very well when stock. It's entirely typical for ITR motors to dyno around 160.

Victor's completely stock '97 motor, on the very same day, dyno'd 162 hp.

I think there's a parasitic loss involved w/the Torsen axle's putting the power down to the dyno rollers, and it's really only appropriate to compare one ITR motor to another one.

Most of the information being presented in this thread could be entirely inappropriate if you're comparing w/a B motor dyno w/an open differential.

 

GK: thanks for the non-judgemental post.

Even though the ITR is a good bit different than the GSR, they're both B-series motors. It's well documented that ITRs make huge gains with proper exhaust setups and good tuning. But as you noted, the motor has a lot of incremental improvements that when added up, create somewhat of a need for the extra exhaust flow such that opening that end of things up makes the extra hp. It's not totally irrelevant and as Trey pointed out, a 2.5" header can make power on a lesser B-series motor. Just that the gains are not going to be as consistently impressive as what's seen on an ITR.

The overall point of my post which has been "disagreed" with was that the original poster should in fact do exactly what the "dissenters" say. There is no need for certain folks to "disagree" for purposes of yet another theoretical debate that derails a thread.

If people want to debate general theories and principles on any one particular aspect of tuning, they should make a thead about it instead of derailing a thread that asks a specific question about a specific car. That is all.

 

As a side note when I have modifieds GSR motors I have found the biggest improvement to be in the intake system. Anyone found something different?

 

No disagreement there. The OEM intake is much less efficient on the GSR vs. the R.