first of all im doing late night web surfing which brought me to making this thread lol........
anyways my vtec engages at just around 5900-6100 rpm somewhere around there by far the highest engagment point of all my cars. my old preludes (H22A1) and civic si (k20) vtec engaged at about 5500ish (if i remember correctly) im running a chipped p08 ecu, my question is do u think its vtec opens to late. btw as far as i know i have no rev limit ive taken it to about 8500rpm (iknow crazy.. i just wanted to see where the fuel cut was and it didnt cut at all).i plan on chipping a p28 ive come across chips for the p28 which have vtec opening at 4600-4900 do u think thats to low? dont think it matters but its a 96 CD7(obd2) jumped to the obd1 p08.

 

honestly vtec engagement has no specific number. stock vtec ecu's have multiple crossover points based on load speed surroundings etc. you should have vtec set to "kick in" when the low lobe stops making power, or SLIGHTLY before so you have as close to a perfect cross over as possible. to achieve this you need to dyno tune it. as far as your ecu goes, why waste money on chipped p28? your p08 is already chipped on something, i'm assuming crome? once teh ecu is chipped it doesn't matter what the ecu name was, it's now a honda ecu running whatever tuning software you have.

also, buying just a random chip with a pre loaded tune on it is not a good idea, especially if you're getting an ebay one. you should put your car on a dyno, and have your tuner turn your rev limiter back on while they're in there.

 

too high for stock cams. on stock cams the range is usually going to need to be 4600-5500. with a chipped p08 you need to go get it tuned.

 

JDM h22a from factory on a P13 vtec enguages at 5,000rpm, this was created by Honda for a reason because it was the best powerband given for a stock jdm h22 motor. I would set rev limiter for 8000rpm because there is no power being created after 7500-7800 rpm on a stock h22. Use your P08 or p28 get a nice tune and adjust your vtec and rev limiter to appropriate setting according to your setup.

 

i have a semi built b16 tuned on crome and vtec engages around 7k
i feel i could definately benifet from a lower crossover point anyone agree??

 

Have you ever looked at a dyno graph for a stock motor? The giant spike when VTEC kicks in is a pretty clear indicator it is not the best powerband (granted a lot of that is in fuel trim & timing as well) - Honda was going as much for the kick as anything else.

As DCRB already said, the engagement point is totally dependent on the cams and the motor and where they are making power. You should make a dyno run with only the low cam engaged, then only the high cam engaged, and set it close to where the graphs intersect so you have a nice smooth torque curve. As also mentioned, engine loading changes some of this as well.

OP, is this a stock motor? And where did the chip come from? Sounds like it's time for a (re)tune.

 

as far as i know its a stock h22a. i put it in myself. i got the ecu from a friend who got it from a friend who got it from a guy with a h22a hatch (my ecu is a **** lol) yes id like to re-tune just dont have the time or money. i rarely open vtec anyway, only when i feel like it.

 

you either need to find a stock ecu or get it retuned. you really have no idea what you fuel / timing curves look like. you could be running your engine lean and doing damage. or running way rich and wasting gas.

 

Actually, stock VTEC engagement is at 5.2K RPM for stock cams. Mine right now engages at 5.7K RPM due to the high lift cams of the pro2s and is where it makes good power.