Hey I have 2 questions about tuning I wanted to know what to do.

My first question was what to do about rev limiters.

How do some tuners address the rev limit on motors. Instances where you know the motor is physically capable of revving higher but doesnt necessarily make more power. What is the safest way to allow the engine to rev til it "runs of of air"?

My second question is tuning drive-ability. I have an issue with transient throttle. quick stabs and the motor bucks... I have talked to a friend and he said that the map sensor on the engine needs some type of vacuum dampening inorder to smooth out readings to the ECU.
Has any one heard of that being an issue?

 

to the first question; you just simply tune it to the RPM you want as a rev limit. just because power drops off doesn't mean that the engine doesn't need the proper AFR and timing, although it should get less sensitive.

you could try removing a couple degrees of timing, and possibly add a little fuel, and that would drop even more power up top, it may give the driver the signal to shift up.

 

That is what I did it makes peak power around 6k and powers falls off pretty hard at about 7.2k but the rate that the engine increases rpm still relatively quick...

Does any one have any information about my second issue. I cant seems to figure out what's the problem. On the dyno its really hard to replicate the sudden jab in throttle and load change. I dont know what I am missing.

 

What ECU are you running? Different platforms handle transient throttle differently so the solution to the problem will depend on what ECU it is

 

I have a progressive limiter on my engine, at 9000rpm it adds about 20% extra fuel, and at 10,200 it cuts the fuel entirely with a wide hysteresis. You could still free-rev it right on up to the fuel cut, but the fuel dump kills power so it is unlikely that I'd ever hit the hard rev limit under load, which is a Bad Thing To Do no matter if it's a fuel or ignition cut.

In practice, under load the engine goes right up to about 9500 and just sort of stops as the wheelspin drops with the reduced power. If I keep my foot in it, it goes higher, after the tires have caught up, but this takes a deliberate effort on the driver's part.