LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

question post dyno/xe cam,knock

Old Jul 22, 2004 | 08:11 AM
  #1  
besz28's Avatar
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From: hudson,florida
question post dyno/xe cam,knock

hello everyone ok heres the deal i got my car dynoed about a month ago, i have the mods in my sig, wound up with 386rwhp with cut out open, and 379rwhp with it closed. perfect air/fuel but i was showing 16degrees of knock at wot and 17degrees with cutout open.also my car stopped making power at 5900rpm. i know the xe cams are known to do this but at 5900?bryan at pcmforless did a mail order tune ,he mentioned maybe valve float, i have comp r lifters and the double springs from lloyd so i don't really think so.the guys at the dyno want to do a dyno tune for 400. money is not a problem but what can they really do?desensitize my lt4 knock module?brian can do that for a lot less.like i said everything else looked real good. what should i do? 400 for dyno tune, or send my computer back to bryan at pcmforless and he said he can tweak it and desensitize my knock module.any thoughts on this as well as why my xe 230/236 cam is stop making power at 5900 is greatly appreciated.
Old Jul 22, 2004 | 11:04 AM
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Re: question post dyno/xe cam,knock

Roller rockers? Self aligning or non self aligning? How much clatter do you have going on under the hood?

I finally just disabled my knock sensor in the PCM. There is just too much noise for it to filter properly on my car. You could always have your tuner fiddle with the knock settings to lower the peak retard and fastattack settings. Might help alleviate, but sounds like you have enough noise that you will always be running retarded 'cus the knock module can't filter correctly.

If the timing is tuned a bit below the ragged edge, then imo you can get away without the knock system. Just imo though heh.

Good luck.
Old Jul 22, 2004 | 11:08 AM
  #3  
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Re: question post dyno/xe cam,knock

non self alighning, i know i can have bryan at pcmforless disable my knock sensor, should i have him do it for 20 bucks for shipping or should i get the car dyno tuned for 400. bryan already did all the work ie:gear change,cam,turned on the fans etc. etc... i hate to pay someone 400 more for a dyno tune when i already had it programmed and just need someone to desensitize or disable the knock sensor.and yes i do have 1 or 2 noisy rockers on the passenger side so iam going to readjust them 0 past lash.thanks again
Old Jul 22, 2004 | 11:22 AM
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Re: question post dyno/xe cam,knock

My setup peaked @ 6k rpm with lloyds heads and 987 dual springs.
Old Jul 22, 2004 | 11:28 AM
  #5  
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Re: question post dyno/xe cam,knock

Did you get A/F ratio printouts with your dyno? if not, i would dyno tune it. If you did, let brian look at those and change the knock rates and the fuel tables for WOT.
Old Jul 22, 2004 | 11:46 AM
  #6  
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Re: question post dyno/xe cam,knock

Originally Posted by besz28
non self alighning, i know i can have bryan at pcmforless disable my knock sensor, should i have him do it for 20 bucks for shipping or should i get the car dyno tuned for 400. bryan already did all the work ie:gear change,cam,turned on the fans etc. etc... i hate to pay someone 400 more for a dyno tune when i already had it programmed and just need someone to desensitize or disable the knock sensor.and yes i do have 1 or 2 noisy rockers on the passenger side so iam going to readjust them 0 past lash.thanks again
NSA are so loud, I wonder if you will ever get accurate knock readings with a loud valvetrain. If you do disable it, then I'd just suggest a tune that errors on the side of caution. Plenty of old cars with no knock sensor, but we are pretty high compression ratio and usually tuned to the edge (and that seems to be where the knock sensor really pays off with "on the edge" tuning).

Good luck.
Old Jul 22, 2004 | 11:54 AM
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Re: question post dyno/xe cam,knock

Comp R lifters are very sensitive to preload, check all your rockers. A dyno tune will win hands down over a mail order tune. Monitoring the air fuel ratio and adjustings the fuel/spark maps will get the most power.
Old Jul 22, 2004 | 12:00 PM
  #8  
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Re: question post dyno/xe cam,knock

man realquick that is one beautiful car,i went to your site and our mods are almost identical except for that supercharger your doing now ,even that lt1 on the throttle body is the same as mine. i made 386rwhp and 356torque very similiar to yours and my cam fell on its face at 5900-6000 like yours hey i guess these xe grinds just do that. anyway good luck with your car and thank you to everybody that added anything
Old Jul 22, 2004 | 12:44 PM
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Re: question post dyno/xe cam,knock

Originally Posted by besz28
man realquick that is one beautiful car,i went to your site and our mods are almost identical except for that supercharger your doing now ,even that lt1 on the throttle body is the same as mine. i made 386rwhp and 356torque very similiar to yours and my cam fell on its face at 5900-6000 like yours hey i guess these xe grinds just do that. anyway good luck with your car and thank you to everybody that added anything
Thanks bro. Lloyds heads are pretty consistent and it shows with his flow numbers and with dyno numbers. I bought the car bonestock with 38k miles. It now has just under 55k and it is where its at. the last two years I have put less than 5k miles on her. I actually held off on the blower install. I am building a forged 383 to put the blower on. AFR heads and a custom cam spec'd by Bret Bauer are some of the ingredients Take care.
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