Raising my redline... B18C1 - Honda Forum / Acura Forum

Sirfallsalot243 · 07-20-2007, 03:10 PM

Im looking at raising the redine on my Semi-built GSR. Internally, its got B16 pistons, stock rod bolts, stock head studs, stage 3 crower cams, manley retainers, and supertech valvesprings. My redline right now is 8500rpm. The reason I want to raise the redline is because with my cams, the VTEC engagement point is at 5950rpm. When I shift from first to second, the car drops out of VTEC for a second, and almost bogs before re-engaging. The higher redline would allow me to shift later, landing in VTEC for second gear. Occasionally I can rev the engine higher than 8500 without the rev limiter kicking in, and it will go right into vtec when shifting to second. The difference in speed is pretty noticeable. My concern is that a 9000rpm redline will be too high for the stock rod bolts and head studs. They both only have 3000 miles on them, but foolishly, I didnt upgrade to ARP. Do you guys think i'll be OK revving to 9k with these rod bolts? I dont want to blow this motor up, but Id like to get all I can out of it.

charliemopps24 · 07-20-2007, 03:14 PM

I'd get a chipped P28 with chrome. I wouldn't raise it past 8750, but i'd feel better with you dropping vtec to 5750 rpm.

Sirfallsalot243 · 07-20-2007, 03:17 PM

Quote:

Originally Posted by charliemopps24

I'd get a chipped P28 with chrome. I wouldn't raise it past 8750, but i'd feel better with you dropping vtec to 5750 rpm.

Im already running a chipped P28 with Hondata S200, tuned on a dyno. VTEC was set where it is because thats where it needs to be. Any lower or higher, it makes less power (either before or after VTEC). My tuner set my VTEC point by dynoing the engine with no vtec at all, and another run with it in VTEC the whole time. VTEC is set at the point where the two dyno plots cross (IE the low duration lobes die out at high RPM, and the high duration points suck at low RPM). The point where they cross is the IDEAL location for VTEC to engage.

Snoopy · 07-20-2007, 05:07 PM

get a b16 tranny

NSZteg95 · 07-21-2007, 12:36 PM

I've read in an article over on TI, to find the ideal VTEC activation point, that you should dyno the car with VTEC deactivated, find the point where power levels/falls off, and set VTEC to activate 200 rpm's before that point.
I think you'd be better off lowering VTEC than raising redline also. Maybe your upgrades in the head can handle the extra revs, but it's not good for your GSR crank and other related bottom end components in the long run.

sleeper15 · 07-21-2007, 06:19 PM

What i did was get a chipped p28 with a programming that didn't have a rev limit set, then got a MSD ignition setup that allows me to change the rev limit. I was oringally going all the way up to 9000 rpm, but after some tuning, i found that 8600 was just perfect for the car, and my vtec kicks in around 5800. Oh yeah, i'm running a b16 tranny myself, and havn't had an issue of dropping out of vtec while shifting in the lower gears.

So, if anything, changing your gear ratios might do the trick for keeping you within your vtec range, but, it's more expensive then just retuning the computer.

gurusan · 07-22-2007, 06:14 AM

the b16 or ITR tranny is what you want. also will help with acceleration.

Franky299 · 07-22-2007, 08:08 AM

i thought you were done doing shit to the car.

and it doesnt need to go any faster and sooner or at all

98vtec · 07-23-2007, 11:16 AM

just raise it. If i can take my stock h22 to 8200, you can take your smaller displacement rev happy b18c1 to 8700 easy.

NSZteg95 · 07-23-2007, 08:36 PM

^^^You have over 20,000 posts on this site and your giving out reasoning like that? Scary.

There's a reason that the ITR crank is better balanced and made of more rigid material than a GSR crank....and that's for handling a mere 400 extra revs while maintaining long term reliability. If he's at all concerned about the longevity of his engine, he shouldn't raise his redline any further unless beefing up the bottom end is in the game plan in the near future as well.

Snoopy · 07-23-2007, 09:58 PM

Quote:

Originally Posted by NSZteg95

^^^You have over 20,000 posts on this site and your giving out reasoning like that? Scary.

There's a reason that the ITR crank is better balanced and made of more rigid material than a GSR crank....and that's for handling a mere 400 extra revs while maintaining long term reliability. If he's at all concerned about the longevity of his engine, he shouldn't raise his redline any further unless beefing up the bottom end is in the game plan in the near future as well.

it was also designed to handle that "mere 400 extra revs" for longer sustained periods of time. itr's were designed to see track duty. and as far as i know, itr and gsr cranks are made of the same material, just itr cranks are heavier.

98vtec · 07-23-2007, 10:54 PM

meh, just sharing my experience. Engines are as weak and feeble as you may think.

NSZteg95 · 07-23-2007, 11:12 PM

Quote:

Originally Posted by Snoopy

it was also designed to handle that "mere 400 extra revs" for longer sustained periods of time. itr's were designed to see track duty. and as far as i know, itr and gsr cranks are made of the same material, just itr cranks are heavier.

Yep.
and the ITR crank is made of more highly rigid steel to increase its fatigue limit by 25% over the GSR crank.

98vtec · 07-23-2007, 11:43 PM

i'd still like to know why you think a GSR with a built head cant safely rev to 8700.