Yeah, I was just talking about swapping the cat out for a test pipe with no tune. Lowering VTEC regardless of anything else will have a big increase in the mid section. In my opinion the mid range is where you want the biggest gains anyway. I'm a little biased since I auto-x, but most of your time isn't spent at peak RPMs on the street anyway. Gernby had a nice write up awhile ago on how to tune out the VTEC transition to get a nice smooth powerband. If I can dig it up I'll post a link.

 

Does the optimum lower vtec engagement point differ depending on the modifications you have on the car? I'm assuming that's why an e-tune or dyno tune is beneficial? Or is there a set number that everyone drops the VTEC engagement point to?

 

It depends on some mods. I know that you can drop it much lower with a test pipe vs. the stock or HF cat

 

There are some general rules of thumb. The way I understood it, you would be at the optimum once you get no spike in the dyno chart at the VTEC transition point (RPM).

 

this is true. the way to do it really is run it on the low cam to redline. then run it in vtec from very low to redline. where the horsepower lines on the dyno graph cross is where vtec is set.

 

this is true. the way to do it really is run it on the low cam to redline. then run it in vtec from very low to redline. where the horsepower lines on the dyno graph cross is where vtec is set.
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Can the datalog pulled from Flashpro identify this?

 

Here is my dyno plot. Bottom thick red line is from a stock Ap2, thin red line in the middle is my car with Evans tune and 3900 rpm vtec, thick red line on top is my final tune done by UMS and vtec at 4200rpm. Notice the 5lb ft torque gain that was made by moving vtec from 3900 to 4200.

K&N FIPK, 70mm Invidia Test Pipe, Greddy Spectrum Elite Dual, Flashpro. 2008 CR

http://www.flickr.com/photos/41071623@N03/6834570008/http://www.flickr.com/photos/41071623@N03/6834570008/ by http://www.flickr.com/people/41071623@N03/, on Flickr

 

I believe this mod should def. be done if you have a quality header/tp/non restrictive exhuast - 76mm...at least the TP / Header, no point in tuning and lowering v-tec w/o these mods first. You need to be able to move the air out quickly enough..first focus on the bolt-ons then the tune...the stock ECU is capable of handling the flow of the bolt-on w/o a tune. You will def. pick up a fair amount of ponies with a tune..I was told by realiable tuner, Jeff Evans that he can make 230hp for me with a K-Pro - stock intake, hytech header and tp and 76 mm exhaust.

 

I've found the limiting factor in lower VTEC engagement to be exhaust flow through the cat. The better flowing the cat, the lower VTEC can be set. You can tell the cat doesn't flow as much as it needs by the AFRs going rich at the VTEC engagement point and not being able to tune this out. The dip in hp is a result of the AFR going rich. I think I've seen elsewhere that you have a HFC or test pipe(maybe you're considering one). If so, keep dropping the VTEC engagement point until you see richness at cutover on the flashpro datalogs that you can't tune out and raise it back a notch so you don't get the dip. Of course you don't want to go too low, but I'm not sure where that limit lies.

 

I totally disagree based on my experience. I never bought into the header being a weak link, fact is that though its a bit heavy, its very well designed to support a broad power band. The cat back isn't bad either, but of course a system with non reflective type mufflers will be an improvement through the powerband based on turbulence, but it will be minimal because that turbulence is at the end of the system. The 60mm diameter isn't a hindrance (until you close in on 400whp based on my SC experience) on the contrary, its sizing supports a fatter mid range unlike larger diameter systems, coinciding with the factory header design. The weak link plug in the system is the cat. Unbolting this with an otherwise stock exhaust stem shows vtec gains typically in the 3500rpm range. Mine is set at 3500rpm because it makes power there. Dollar for dollar, you will get much more use out of simply swapping out the cat for a TP and re tuning the car. Get a cat back if you like sure, but leave the header alone. If you care about maximizing the mid range power band of the F22, this is where its at. And good news is, you don't have to spend a fortune to get there.

Also depending on the year of the car (+02 and especially 04+) if you got some good bolt ons which provide a worthwhile increase in flow, the stock ecu will not accommodate the added fuel needed to support this. A TP is about it, beyond that you should plan on incorporating some measure of additional fuel, either from as simple as an adjustable fpr to turn up fuel pressure, to a full ems. Beyond about 13-13.5 afr you will be past lean best, run dangerously hot combustion temps and will start losing power. The factory ecu with cat puts the car in the 12's on years mentioned, a TP runs you near a full point leaner. You need a tune beyond that not just to maximize your gains, but to run safe.