knock retard at high rpm's-what can it be??
01-30-2002, 03:23 PM
#1
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knock retard at high rpm's-what can it be?? I can't get rid of this knock retard I have in 4th gear only.
I've tried running 100 octane fuel and the knock is still there. This is what I don't get. In 1st-2nd and 3rd gear from idle to the rev limiter, I have 0.0 knock retard. In fourth gear above 4300 all the way to the rev limiter I get about 3.4degrees on kr, and then it slightly goes down all the way to 6100 where it is about 1.9-2.2 degrees.
It ONLY does this in 4th gear. On the dyno, my timing drops from around 26.5 to 21.5 as soon as the KR kicks in around 4300 up to the limiter. When I auto tap at the track, same deal. 0.0 1st-2nd-3rd,but in 4th around 4300 and up..a little knock jumps in and timing goes down a little. Track times are good and dyno numbers are good, but this has to be hurting me a little.
What can this be? Is it possible it' some type of harmonic vibration causing false knock? What else can it be?
Pushrods have all been replaced and I run 93 octane Amoco ultimate, or 93 octane Mobile 1 at all times. Any thoughts or ideas appreciated.
<img src="gr_images/icons/mad.gif" border="0">
I've tried running 100 octane fuel and the knock is still there. This is what I don't get. In 1st-2nd and 3rd gear from idle to the rev limiter, I have 0.0 knock retard. In fourth gear above 4300 all the way to the rev limiter I get about 3.4degrees on kr, and then it slightly goes down all the way to 6100 where it is about 1.9-2.2 degrees.
It ONLY does this in 4th gear. On the dyno, my timing drops from around 26.5 to 21.5 as soon as the KR kicks in around 4300 up to the limiter. When I auto tap at the track, same deal. 0.0 1st-2nd-3rd,but in 4th around 4300 and up..a little knock jumps in and timing goes down a little. Track times are good and dyno numbers are good, but this has to be hurting me a little.
What can this be? Is it possible it' some type of harmonic vibration causing false knock? What else can it be?
Pushrods have all been replaced and I run 93 octane Amoco ultimate, or 93 octane Mobile 1 at all times. Any thoughts or ideas appreciated.
<img src="gr_images/icons/mad.gif" border="0">
01-31-2002, 08:43 PM
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Re: knock retard at high rpm's-what can it be?? when you say balancer, the H balancer ? If it was this it should be doing it in every gear at the same rpm, what gear you are in only effects the speed of some drive train components.
Can you feel any vibration in the car itself at higher MPH..Maybe the driveshaft is out of balance cause a knock through the box to the motor. must be something to do the the driveline speed. Or remotely the car is leaning when it reaches the top end of things (fuel supply issue), but would see that on the dyno.
[ January 31, 2002: Message edited by: vt2vx ]</p>
Can you feel any vibration in the car itself at higher MPH..Maybe the driveshaft is out of balance cause a knock through the box to the motor. must be something to do the the driveline speed. Or remotely the car is leaning when it reaches the top end of things (fuel supply issue), but would see that on the dyno.
[ January 31, 2002: Message edited by: vt2vx ]</p>
