Lack of oomph at high rpm?

[jabroni95gsr]

Ok, so i have only put on about 1000 miles since installing the jrsc on my integra...but one thing that has sort of irked me is the lack of high rpm rush. Maybe its because i don't hear the wail of the na intake noise (which i dearly miss), but the car doesn't seem to pull from 5-8k any harder then it used to. Ok, 1st gear seems quicker.

Don't get me wrong, the tq down low is great. the car even pulls good below 2k and then till about 4 - but then its like things even out...just a linear progression till redline. Shouldn't the gears be revving faster? I may be wrong, but i think that my car pre-jrsc would pull just as hard from 6-8k, with the same amount of force. Of course if my car were to race itself, pre and post jrsc, the post car would win because of the lower rpm advantage...but thats it.

So. What could be wrong? belt slipping? no, boost is constant....i think it may be my exhaust - i have the dc 4-2-1, mated to a 100k stock cat, an old greddy 60mm bpipe and itr rear section that is starting to sound crappy. Before i go out and spend a bundle to "open" up my exhaust - can someone confirm that my money will really be well spent? Or at least, opine on some of my observations, pre and post jrsc?

[gsrteggie]

throw it on the dyno, and you can see if u are making power. Also, make sure they use a wideband o2 sensor, to check your a/f.

on a side note, I'd recommend getting a map mod. Mine made a huge difference. I Couldnt run my car without it.

[CROM]

ITR Cat Back = restrictive

-Thats definitely putting a damper on your higher RPM fun. Plus, getting any belt slippage in the higher RPM's?

[mgro]

<BLOCKQUOTE><font size=2 face="Verdana, Helvetica, sans-serif">quote:</font><table border="0" width="90%" bgcolor="#333333" cellspacing="1" cellpadding="0"><tr><td width="100%"><table border="0" width="100%" cellspacing="0" cellpadding="2" bgcolor="#FF9900"><tr><td width="100%" bgcolor="#DDDDDD"><font size=2 face="Verdana, Helvetica, sans-serif">Originally posted by jabroni95gsr:
Ok, so i have only put on about 1000 miles since installing the jrsc on my integra...but one thing that has sort of irked me is the lack of high rpm rush. Maybe its because i don't hear the wail of the na intake noise (which i dearly miss), but the car doesn't seem to pull from 5-8k any harder then it used to. Ok, 1st gear seems quicker.

Don't get me wrong, the tq down low is great. the car even pulls good below 2k and then till about 4 - but then its like things even out...just a linear progression till redline. Shouldn't the gears be revving faster? I may be wrong, but i think that my car pre-jrsc would pull just as hard from 6-8k, with the same amount of force. Of course if my car were to race itself, pre and post jrsc, the post car would win because of the lower rpm advantage...but thats it.

So. What could be wrong? belt slipping? no, boost is constant....i think it may be my exhaust - i have the dc 4-2-1, mated to a 100k stock cat, an old greddy 60mm bpipe and itr rear section that is starting to sound crappy. Before i go out and spend a bundle to "open" up my exhaust - can someone confirm that my money will really be well spent? Or at least, opine on some of my observations, pre and post jrsc?</font></td></tr></table></td></tr></table></BLOCKQUOTE>

Check the JRSC homepage for the type-R dynosheet:
http://www.jacksonracing.com/pages/d...tailspage.html
You'll see that for the type-R, the main difference in the torque curve is from 4..7krevs, which doesn't match up with your observations at all- something must be wrong! I don't have a type-R (Civic SI) but I also had a disappointing top end. Two things made a big difference:
- Ingnition timing. I used the conservative settings from the JR manual (I think -7 degrees) which made the car sluggish when not under boost, and weak at high revs. I am now running the stock -16 degrees with a BTC set at about 0.5deg/psi. The difference is very noticeable.
- A/F. After I sorted fuel pump/FMU issues, the A/F at high revs was way too high, again killing the power on top. I decreased the baseline setting of the FMU from 70psi to 55psi which fixed the problem!

Please be careful if you do these things- knock can destroy your engine. I wouldn't have dared to do this without the J&S ultra safeguard!

Good luck,

Mark.

[Ray000]

a test pipe or hi-flow cat will help the car pull all the way through redline. These products are more helpful on FI cars. [img]graemlins/thumbs_up.gif[/img]

[jabroni95gsr]

Well, i have hondata so the map mod and fuel tuning issues are not an option. The car is def not completely tuned, but i did some street wideband datalogging and it was running well. I guess i was just expecting more from the top end. I mean the car seems to really pick up steam and then level off (but still accelerate quickly). I definitely think my cat and exhaust have something to do with it. I might gut my cat and see if it improves anything before i drop $500 for an exhaust and another $150 for a high flow cat. My cat is prob clogged anyway...

[CROM]

Ive had friends dyno their cars with a Type R muffler/exhaust combo and an Apexi and Greddy models and the Type R was significantly more restrictive.

[blownLS]

With an integra with 210,000 miles I highly doubt the cat is clogged at only 100,000 miles. 35,000 of that is forced induction. I just recently replaced the cat with a 2.5" straight through and upgraded to a 2.5" b-pipe. I already have DC 2 piece 4-2-1 headers with 2.25" collector. I gained top end 6000+ but lost just as much below 3000 and my off boost performance suffered big time. I gained an average of 5HP from 6000-8000rpm with the b-pipe and cat replacement and the biggest difference was right at 8000rpm where HP was still slightly increasing compared to before where it was flat after 7000rpm.

My biggest disapointment was at the track where these mods (cat/b-pipe)together only helped by a tenth of a second, in return for an exhaust note of THREE times louder. So loud in fact, I could not hear my 1000 watt JL sound system at cruise. So, I replaced my relatively quiet 2.25" flowmaster muffler with the old stock LS 1.75" muffler. Replacing the old LS muffler only slowed me down by a tenth of a second (so I am back to square one with no gain). But it's a stock look and is stock quiet now until the suppercharger kicks in with a power drill sound.

One hot day at the track last summer I couldn't do any better than a 14.2 with the flowmaster on, so I took it off in hopes to beat a 100 shot nitrous civic doing a 14.1. And much to my amazement I pulled off a 14.05 and beat him by a half a car. This was a good way to test the exhaust potential. The car was so loud I had a headache by the end of the quarter mile. NOT worht the .15 seconds, unless my reputation depended on it.

I would look elsewhere for the missing top-end oomph. Tighten or relplace both belts. Getting your Hondata dyno-tuned by a professional will noticably help. I noticed the difference just starting the car and pulling out of the lot. My track times dropped by a quarter of a second with cooler intake temps.

Anyway, hope this helps...

[jabroni95gsr]

Chris,

Thanks for the comments...i will definitely look into these things. THat is really interesting about the experiences you've had switching exhaust sizes...especially if you consider how the conventional advice is "jrsc? you definitely need 2.5". Just as you have, I too have noticed a drastic difference with the intake temp. I recently used the CAI extension from my iceman intake (i leave it shorty) to create a cold air bath to the filter. basically i just hacked the piping up and built a bracket to hold it in place. It draws air from behind the sidemarker, and then routes the air directly to my filter. It works! Also, since its been relatively hot here in nyc recently i defintely notice a decrease in performance.

[blownLS]

I agree. I am using my passenger high-beam hole as an inlet for my intake by using an 6" Akimoto funnel (window screen covered) connected to 3" intake tubing, hooked to a Ractive heatshield filter and back to 3" tubing to the TB. I notice no difference most of the time, but it is the hot temp days and high speed runs that make it worth while. It adds an additional 1 psi in the traps closing in on 100mph and 2 psi above 120mph. It has helped boost me to a top speed of 152mph (top gear at 7300rpm). Unmeasurable on a dyno due to no ram effect, my GTEC pro consistently measures a difference of 8hp when comparing a 2nd gear run to 4th gear run (60mph vs 115mph). It usually takes 1-1.5 psi to get 8hp at the wheels. So it was well worth the effort.

One thing I have learned about exhaust through reading and trial and error is; there is never free horsepower gained, you are simply removing power from one part of the RPM band and adding it to another.

You should simply tune for a paticular RPM band that you will use the most and then try to match all of your bolt-ons parts, to include cams, intake manifolds, ports and exhaust to match that same rpm band. That is how you extract the most out of your engine. If you are trying to make a dragster then tune for 6500-9000 with a VTEC (5500-8000rpm for non-vtec), if you are trying to make a course car then tune for 4500-8000 (longer race equals less revs and hills to climb in lower gears) and if you are trying to make a good all around street car then tune for 3000-6000rpm (don't worry about peak numbers; i would much rather have a 20hp increase throughout the midrange than a 5hp increase at the peak). It's all about where you are spending the most time in your car. Or think of it this way, when you are accelerating through a gear during a drag race; does your car spend more time reving past 6000rpm or screaming to a blur into redline?

Hope this also helps... Anyone feel free to add their 2 cents... This is my learned experience.