I've seen a few wrecked exhaust valves myself as a result of excessive heat. Metal expands, lubricants break down, etc.

Likewise, one cannot say that a 'quality turbo' will not fail, because unless Garrett doesn't make 'quality turbos', it can, does, and has happened.

 

repost

 

If your in cylinder temps are high yes you can damage valves. However high in cylinder temperature does not always mean high exhaust manifold temperatures.

Have you ever seen the EGT's of a car cruising on the highway creep REALLY high. Like well past 1600F and into 1800F territory. This is fairly common and millions of cars do it everyday, and don't hurt their valves.

 

Maybe, but then again I can't say that I've ever pulled over from a light cruise and lifted the hood only to see an orange hot manifold - unless something was amiss.

Anyway, if this helps to keep things from going in circles, the point is there is excessive EGT isn't 'normal' in the context of this discussion.

 

I aim for 11.2 on 91 oct personally....from all the testing and tuning i have done with my own car I can add decent timing (ranging from 5 down low to 14 up high) and maintain a zero knock environment....

 

what about afrs getting richer by redline?? so when someone is tuning and they are tuning to 11.3 does this mean 11.3 also by redline or do they richen it up by redline?

 

i tune for 11.3- 11.5:1 @ peak torque, tapeing down to 11.1:1 after 6800rpms on pump gas.

CJ

 

thanks for the reply i want to share with you that at peakboost iam runing 11.9 and by redline it tapers to 11.2 and i have zero knock
also when tuning ive seen that i can pull away -3* of timing and my afrs will still be the same so this tells me that we need to play around with timing more then afrs once you have your timing setup where it doesnt knock you can start leaning it out to the point where you hit knock this is just to have more power.

iam using this afrs with 5*at peak boost and by redline 18* using 91oct and 21psi of boost what about timing itune do see it ok?

 

i would run 11.5:1 at peak torque, then taper to your current 11.2:1. Also, when you retard timing, your AFRs usually will go a tad bit richer. i would not lean out AFR's until i hit knock, i would set AFR for what i said above and advance timing 1-2 degs under the knock threshold, if you are not on a dyno. Remember, as you advance ignition timing AFRs will go a little leaner, retard ignition timing and they will go a little richer. As you tune ignition timing, it's important to re-tune AFR's as you make changes.

If you are running 21 peal boost, what are you running at rev-limiter? By the looks of your timing, seems as though you are probably running considerably less than 21psi at redline. Are you getting any knock counts at all?

CJ

 

ive been tuning my car on 3erd gear i dont have knock counts but when i log on 4th gear i do have knock counts maybe i need to pull 1* more degree,also i hit 21psi at 3800rpms and have a spike of 21.5psi at 5000rpms then by 7000rpms i have like 18psi of boost
but yes i might be pushing my car cause of the knock counts i get on 4th gear

 

Richen your AFR's up to 11.5:1 at peak torque(between 3000-4000rpm) and taper to 11.1:1. Retune ignition timing 2 degs under the knock threshold throught the power band. start at 3-4degs at peak torque, going to about 13-14*@ revlimiter.

CJ

 

thanks for your kind and helpful advice