6psi 10* timing and knock retard
6psi 10* timing and knock retard Not sure if this should go in "forced Induction" "PCM and tuning" or "Dyno" thread. It has a little to do with all. Took my car to the dyno shop for a tune. They use the dynapack dyno, which is really nice. Does so much stuff its a sweet machine. I got my VE tables and PE set to what seemed just right. Using HP tuners and a 1 bar SD tune (soon to be 2 bar). First full pull was like 404 hp and 450 tq. at 6.5psi. Now I was looking for close to 500 at 8.5psi, for my final #'s. A little tweaking later and best run of the night was 424hp and 465tq at 6.5 psi. Next we tried to ad a little timing started at 10* moved up to 12* and knock retard took away 4* 
Checked fuel pressure and found it dropped from 60 to 40 after 5000 rpm.
Do these #'s make sence? shouldn't the racetronix keep up? The SVO 42 where still fine. Why couldn't I put more timing in 10* seems like so little? plugs are tr6 gaped .35? Also never run a rubber elbow into the throttle body any more than 6.5 psi blew the damn thing off.
I'm sure I forgot some detail so le tme know what you think or what I left out.
Checked fuel pressure and found it dropped from 60 to 40 after 5000 rpm. Do these #'s make sence? shouldn't the racetronix keep up? The SVO 42 where still fine. Why couldn't I put more timing in 10* seems like so little? plugs are tr6 gaped .35? Also never run a rubber elbow into the throttle body any more than 6.5 psi blew the damn thing off.
I'm sure I forgot some detail so le tme know what you think or what I left out. The fact that your fuel pressure is dropping that much is not a good thing!! That would be why you are seeing knock. What was your afr when that happened? My racetronix pump has kept up just fine so far. No numbers on the new motor, but with my stock motor and 8 psi I hit 475 rwhp. That was with racetronix pump and their 42 # injectors.
I have had issues with the sound of the Turbo actually setting off the Knock sensors... I tune the car in w/o knock sensors, I bring up the timing to find the thresh-hold and then knock 2 degrees off for variables...
Ryan K.
Ryan K.
fp should be a bit higher but if its not lean... false kr, or crap gas... add some 100 oct. if it still does it, desensitize the knock sensors, if its real knock, you'd hear it on the dyno... are you running a low 11 afr?
Yes car is running a low 11:1 Af. You think its false KR? I'm gonna get my 2 bar map sensor, get a silicone instead or rubber elbow! and try and figure out whats up with the fuel pressure. I think I need to describe the fuel pressure drop better. 60psi going great then it doesn't gradualy drop to 40 it drops to 40 right away and then stays steady? Bad pump? regualtor? I'm gonna post this in the Fueling section also. I think the fuel delivery is my 1st thing to fix! called Thunder today said I might as well try a new GM filter first, then see if its there racetronix pump.
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Consider that the torque peak may have well wanted to be at 4400, but instead the high cylinder pressure caused knock, retarded the timing and now the peak occured at 47OO. What were the torque numbers from 4300-4800?
Was there a dip at all?
Remember that knock can be caused from self-ignition and not initiated from the spark timing.
If the dyno is sampling O2 from the tailpipe the readings will lag behind a bit and tailpipe sampling is very averaged. Your fuel pressure changed the injector's flow rating by 10#/hr -20%- and leaning out in the cylinder could have caused enough heat to induce knock.
Was there a dip at all?
Remember that knock can be caused from self-ignition and not initiated from the spark timing.
If the dyno is sampling O2 from the tailpipe the readings will lag behind a bit and tailpipe sampling is very averaged. Your fuel pressure changed the injector's flow rating by 10#/hr -20%- and leaning out in the cylinder could have caused enough heat to induce knock.
I was running two wideband o2's one just after the cat and one at the back after the turbo they always read .2 apart ie 14.7 at the front 14.9 at the rear. the only dip I had was at 3300 when the car whent into PE and is only on a 1 bar tune. Going 2 bar should remove that. 4400rpm no hic up at 4000rpm 400 ft lbs, 4500rpm 450ft lbs, 4700 465, 5000 445, 5500 390, I just changed my fuel filter and did a few 2nd gear pulls I didn't see the pressure drop. My test gauge is taped to the windshield, and is hard too see driving at night. .
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