I have a question about my gsr's vtec engagement. I know that on a stock standard gsr, the vtec engages at around 4400 rpm. My car however, has a chipped P28 ecu to which the vtec doesn't engage until around 5800 rpm or so. My question is this: Is there any benefit to having the vtec engage at a higher rpm? I mean, whether it engages at 4400 or 5800 rpm, it still stays engaged to redline so what would be the benefit of the higher engagement point? The car had this ecu when I bought it so I'm not the one that set it up this way. Anyway, if someone could give me a reasonable explanation I would really appreciate it.

 

camshafts are designed to fit a certain RPM- vtec merely adds an extra set of cam lobes so the engine can have two settings, a low cam for low engine rpm or a high lobe for higher engine rpm's

vtec is best engaged where the torque/horsepower curves intersect, on a stock GSR the stock vtec engagement point is set at 4400 because, plainly stated, thats where the standard and secondary cams meet.

a higher vtec engagment point on a stock GSR does nothing but slow you down off the line. between 4400 and that new point you are losing power, that kick you feel is it catching up with the curve that you could have already been on for 1000rpm--

with that p28 you also lose the ability for the car to operate the secondary intake runners properly, so thats just robbing power from the top end aswell.

 

my vtec engages at 5200

 

5400 here in my B18C1

 

Ideally, you want vtec to engage where the low cam torque curve and high cam torque curve intersect. If it is engaging lower than that, it will feel sluggish/boggy until vtec was supposed to engage. If it is engaging higher than that, you will feel it but the sudden jump in the torque curve will cause a power loss overall.

Unless you are running relatively aggressive cams, you are losing a lot of power and 1400 rpm in which you could be in vtec but aren't. I would suggest having a proper GSR map burnt onto the chip.

 

not unless you have a chipped ecu

 

mines at 4900 RPM and i think its pretty good at this RPM, would not lower it or raise it, im comfortable with it.

 

55 or 58 is average

 

no, 4400 is where it's at stock

 

ugh, you're such a noob

4400 is where the butterflies open h: