Has anybody ever documented the setting of VTEC to 0 rpm or just forcing the bigger profiles from 0rpm on a stock GSR? I'd like to see exactly how the powerband suffers with a stock GSR running the big cams all the time without any fuel map tuning. And then I'd like to see how the GSR would perform on the big lobes when properly tuned (i.e. comparable to a stage 1 LS cam?).
I wouldn't think it would be too difficult to get rid of the "VTEC=Fuel Economy Tool" by preparing a fuel/ignition map to have a nice powerband running off of the big lobes all the time. Should be easier than my tune with the much larger cams....and I have a much nicer low-end powerband than a GSR on the small lobes.
I believe a long time ago I saw something like that, and the car made less power at the low end than with VTEC at the normal crossover. The mild cam profile isn't just for emissions and mileage - big cams typically make less power and definitely make the engine run more roughly at lower rpm. Folks like you and me with LS's with big cams don't really care so much about a bit of a rough edge at idle/low revs, but to the mainstream market this isn't acceptable. But at any rate, it's pointless to have a big cam at low rpm because it will generally make less power than a properly sized cam... if a VTEC-type system is already in place, it's best to use it.
__________________
'98 Integra LS - non-VTEC autocross / daily driver (aka Track-Tested / Mother Approved) Daily-driven 87 octane Porsche destroyer
Latest Auto-X: 5th overall in class (7th/12 Day 1, 2nd Day 2). 10th/92 overall Day 2.
Complete mod list and updated race results here: http://www.freewebs.com/white98ls - don't forget to sign the guestbook! Autocrossing for a day is the best $25 you can spend
^ Agreed. I just figured that since my bigger cams have a 100% perfect stock idle, and my low end is still better than the low end of a stock GSR w/ VTEC...that it wouldn't be so difficult to tune a GSR to have a perfect idle, and better than stock low end while running on the bigger profiles.
Mods: All stock, for now. Hooked up the stereo though.
Setting optimal vtec is easy. Dyno the car once, with vtec disengaged for the whole rev range. Dyno the car again, with vtec engaged for the whole rev range. The first dyno should have shitty top end, but good bottom. The second dyno will be the opposite. Where the two graphs cross is where you set your VTEC.
On a stock GSR, VTEC engages at 4400rpms, and the secondaries on the intake manifold open at 5750rpm.
Integra Arsenal:
1991 LS Special Ed- Sold.
1997 GSR- 192whp 130wtq all motor. SOLD
1991 GS- automatic daily driver. FOR SALE. $1500 PM for details.
1998 Nissan 240SX SE New!
And a 2000 Suzuki SV650
Mods: All stock, for now. Hooked up the stereo though.
Quote:
Originally Posted by leem21vtec
damn I wish mine kicked in at 4400rpm, instead its at 5600rpm then again its a b17a1 not a b18c1
B17's use a single stage intake manifold (like the B18C5). The GSR uses a 2 stage IM, which allows for better bottom, at the sacrafice of top end. A single stage manifold is designed for high RPM flow (which is why many GSR owners upgrade to a Skunk2 single stage IM).
Integra Arsenal:
1991 LS Special Ed- Sold.
1997 GSR- 192whp 130wtq all motor. SOLD
1991 GS- automatic daily driver. FOR SALE. $1500 PM for details.
1998 Nissan 240SX SE New!
And a 2000 Suzuki SV650
Mods: 17"x 7.5" Rims, Nitto Neogen Tires, Energy suspension bushings (engine, suspension and trans) B&M Racing shifter, Antenna block of plate,
i used to have a 95 GS-R and was on a GS-R only forum and lots of people would block off the secondary butterflies open for a better power band. i tried it and it felt stronger but didn't ever dyno it to see. other people would take an ITR intake and modify it so it would fit since the bolt pattern is different.
i used to have a 95 GS-R and was on a GS-R only forum and lots of people would block off the secondary butterflies open for a better power band. i tried it and it felt stronger but didn't ever dyno it to see. other people would take an ITR intake and modify it so it would fit since the bolt pattern is different.
I bet if there was a dyno, it would prove the opposite... any perceived improvement was most likely psychological, due to hopeful expectations and extra sound. The fact is, the manifold is two-stage to increase power since a longer path is beneficial for low revs and a shorter path is better for high revs.
__________________
'98 Integra LS - non-VTEC autocross / daily driver (aka Track-Tested / Mother Approved) Daily-driven 87 octane Porsche destroyer
Latest Auto-X: 5th overall in class (7th/12 Day 1, 2nd Day 2). 10th/92 overall Day 2.
Complete mod list and updated race results here: http://www.freewebs.com/white98ls - don't forget to sign the guestbook! Autocrossing for a day is the best $25 you can spend
Mods: B18C1 swap, fully built for turbo,195whp as of now w/hondata s200, boosting soon
Quote:
Originally Posted by Michael Helmke
i used to have a 95 GS-R and was on a GS-R only forum and lots of people would block off the secondary butterflies open for a better power band. i tried it and it felt stronger but didn't ever dyno it to see. other people would take an ITR intake and modify it so it would fit since the bolt pattern is different.
i took my secondary butterflies out all together and when my vtec hit the diffrence is deff noticable. think about it your intake is that mu ch larger and open at all times not just after 5800 rpms
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