hi i was researchin on ht.. and some ppl on ht says "vtec engage at 4400rmp and something at 5500" dont know wats its call... and my motor only redline a 7000rpm i thought its suppose to be 8000rpm?? i have jdm b18c and p72 ecu in a 97 dx.... is it the butterflies not hook up? can some one tell me wats wrong?

 

The b18c is sort of a funny engine when it comes to vtec, because of the dual intake runners change over. It is sometimes argued, but I'm pretty sure vtec engages at 4400, and the intake crossover is at 5750-5800. The butterflies give it the audible sound of vtec engaging at 5800, but I'm pretty sure that it's supposed to engage at 4400; it tends to be very subtle on an unmodified b18c. Now, if the rev limiter is engaging at 7000 RPM's, there is a problem. This could be due to a few different things. First off, are you throwing any codes? What engine harness are you using? If using a b18C harness, not having the butterflies hooked up should throw a code and there would be no vtec at all. If using the B18C harness, is it out of an OBD1 integra or OBD2?

If using the civic dx harness, the car would of had to of been wired for the butterflies and vtec. If the car is rev limiting early I would start with the ECU. If there is another OBD2A p72 (if car is still wired to be OBD2A) available to you, I would try that. If it does the same thing, then it could be the distributor going bad. I've seen this happen before where the tach would be off and the rev limiter would engage early due to a bad distributor. Either way, I would probably get an OBD2A to OBD1 jumper harness and run a socketed and chipped OBD1 ecu with a basemap for that engine, there are slight differences between the Jdm b18c and the usdm b18c1, such as compression. Hope you get it figured out.