Low dyno numbers on the 383
Dec 25, 2004 | 10:10 PM
#11
if you droped your kr cells to 4deg and are seeing 4 deg of KR then you have knock that the pcm can't do anything about. i am not sure if i understood what you said but i think i understood that corectly. maxing the KR is a very bad thing.
Dec 25, 2004 | 10:20 PM
#12
Staging Lane
Joined: Jan 2003
Posts: 74
Likes: 0
From: Moreno Valley
Originally Posted by ktmrider
I finally had a chance to dyno the 383 iron stroker in my signature. I was hoping to see 350/350 wheel hp/trq.
Final numbers were very disappointing. Torque was there, 365, but the HP was tops at 280.
The dyno curves were very wavy thru the RPM band and you can feel the truck fall flat above 3500 rpm.
I have been tuning with the stock O2 narrow band charts. The dyno shop thinks it is running very rich, and the HPT shows 4000+ to have -5 to -7 cells. I thought this indicated a lean condition?!? I am also concerned that the head work I had done might also be to blame ( 6.0 valves, 3 angle, slight polish work ).
Anyway, any feedback is appreciated.
Final numbers were very disappointing. Torque was there, 365, but the HP was tops at 280.
The dyno curves were very wavy thru the RPM band and you can feel the truck fall flat above 3500 rpm.I have been tuning with the stock O2 narrow band charts. The dyno shop thinks it is running very rich, and the HPT shows 4000+ to have -5 to -7 cells. I thought this indicated a lean condition?!? I am also concerned that the head work I had done might also be to blame ( 6.0 valves, 3 angle, slight polish work ).
Anyway, any feedback is appreciated.
http://www.cranecams.com/?show=newsLetters&no=65
Ken
Dec 25, 2004 | 10:47 PM
#13
Originally Posted by ktmrider
You know, one thing I totally forgot about was that I bought a "used" ASA timing assembly from eBay ( 2 dyno pulls of use ). I wonder if I used the wrong keyway ( it is keyed for +/- 3 degrees ) and am advancing the timing too much?!? That would explain the top end falloff and excellent low end torque, plus some of the KR at high rpm's. Coulda swore I used the center key but it was 1000P at the time and I was running from the oven to the crank snout after heating it up.
Too bad it will take a total teardown to verify. Maybe an excuse to swap the cam?!? A good excuse at that....
Too bad it will take a total teardown to verify. Maybe an excuse to swap the cam?!? A good excuse at that....
https://ls1tech.com/forums/showthread.php?t=251980
Dec 26, 2004 | 12:07 PM
#14
Thread Starter
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Joined: Apr 2003
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From: Albuquerque, NM
Originally Posted by parish8
if you droped your kr cells to 4deg and are seeing 4 deg of KR then you have knock that the pcm can't do anything about. i am not sure if i understood what you said but i think i understood that corectly. maxing the KR is a very bad thing.
Looking at everything now, I am pig rich at all throttle positions above 40% with both O2 sensors maxed out at 900+ at 40% throttle at all RPM's. The advance table shows a similar situation, it has very low advance from 40% / 2500rpm with some WOT advance at -5.
Boy, it just goes to show how a little knowledge goes a very little way with the tuning software.
Thx greentahoe for the thread from Ranwalk. Good chance I am a little advanced on the cam but more likely I am just being stupid on the fuel tables. The dyno operator thought a rich fuel condition would cause the graphs he saw and the scanner supports this. I also just read that the truck ECU tends to run richer than the car programs. I just need to get a little more humble and ask for some help!
Dec 26, 2004 | 08:32 PM
#15
Launching!
Joined: May 2004
Posts: 287
Likes: 0
From: Tuscaloosa, AL
If it is not tuning thats causing its the cam is not in straight up which you have already said.
What kinda valvesprings do you have. Valve float on the dyno will look like eractic high and low spots in the power curve. Although since you have an LS6 cam (which is way to small), wouldnt need very much vlave spring pressure to run.
What kinda valvesprings do you have. Valve float on the dyno will look like eractic high and low spots in the power curve. Although since you have an LS6 cam (which is way to small), wouldnt need very much vlave spring pressure to run.
Dec 27, 2004 | 01:13 AM
#16
tuning could easily be the problem. too much fuel and too little timing is no good for power.
i just noticed this is on a 99 truck. i had teriable problem swith false knock on my 99 and was probably a full sec slow because of it. i got to get to bed now but will post up a little more on that tomorrow.
i just noticed this is on a 99 truck. i had teriable problem swith false knock on my 99 and was probably a full sec slow because of it. i got to get to bed now but will post up a little more on that tomorrow.
Dec 27, 2004 | 03:26 PM
#18
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Joined: Apr 2003
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From: Albuquerque, NM
Originally Posted by N20GMC
If it is not tuning thats causing its the cam is not in straight up which you have already said.
What kinda valvesprings do you have. Valve float on the dyno will look like eractic high and low spots in the power curve. Although since you have an LS6 cam (which is way to small), wouldnt need very much vlave spring pressure to run.
What kinda valvesprings do you have. Valve float on the dyno will look like eractic high and low spots in the power curve. Although since you have an LS6 cam (which is way to small), wouldnt need very much vlave spring pressure to run.
Thanks for the follow up Jim/Parish, I welcome any suggestions.
I am thinking that even with some good tuning I may not see more than 30-40 hp increase with the Z06 cam. Most everyone agrees, the cam is WAY too small for the engine.
OK, now that the general consensus is in, how bout some cam suggestions? Some background info, we are emission tested every year here. The truck is 4wd ECSB and a daily driver. It will go to the track maybe once a year and mostly carry around dirt bikes. Anything that will provide good low end torque ( even with the stroker cubes ) and an occasional dyno/track pull is the best option.
Again, can't thank you all enough for the help and diagnostics!
Dec 27, 2004 | 07:57 PM
#20
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From: Albuquerque, NM
Originally Posted by parish8
i think it was just the 99's that had the false knock problem, not sure if you can just swap it out or not.
I tried to have a 6.0L ECU map programmed in before getting the HPT but no one was willing to do it. Now I am realizing how little I understand about the HPT, time to start posting on their website for help.