Help with Low Dyno numbers
Thread Starter
Teching In
Joined: Sep 2017
Posts: 34
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From: Edinboro, PA
Help with Low Dyno numbers Hi guys, I was hoping I could get some help on these low dyno numbers after having a freshly built engine.
I have a genIV 6.0 aluminum block with the stock flat top pistons, stock rods and crank. It has a Custom TSP cam 231/242 @.629/.615 lift 112LSA +4. I’m running stock LS3 heads 823 casting, and a FAST LSXR intake and 102mm TB. Using 1 3/4” long tube headers into 3” exhaust with an X pipe and Borla mufflers. 255lph fuel pump, 42lb injectors @58psi.
The drivetrain is a built 4l80e with a 3200 stall and 3” steel driveshaft. I’ve got big heavy 20x10 wheels.
So I would’ve thought I’d make pretty decent numbers but on the DynoJet at SAE Smoothing 5, I’m only making 319whp. So even if I compensated for a 25% drivetrain loss, I’d only be making 400hp at the flywheel. Do you think this is actually right?
I have a genIV 6.0 aluminum block with the stock flat top pistons, stock rods and crank. It has a Custom TSP cam 231/242 @.629/.615 lift 112LSA +4. I’m running stock LS3 heads 823 casting, and a FAST LSXR intake and 102mm TB. Using 1 3/4” long tube headers into 3” exhaust with an X pipe and Borla mufflers. 255lph fuel pump, 42lb injectors @58psi.
The drivetrain is a built 4l80e with a 3200 stall and 3” steel driveshaft. I’ve got big heavy 20x10 wheels.
So I would’ve thought I’d make pretty decent numbers but on the DynoJet at SAE Smoothing 5, I’m only making 319whp. So even if I compensated for a 25% drivetrain loss, I’d only be making 400hp at the flywheel. Do you think this is actually right?
What did the vehicle dyno before the new motor? Did the truck have the 4L80E & 3200 stall? Dyno's are best viewed as tuning tools etc.
Who manufactured the 3,200 stall converter? Some are very inefficient. Likewise, a lot depends on how the 4L80E was rebuilt too.
How does it run at the track and on the street?
Who manufactured the 3,200 stall converter? Some are very inefficient. Likewise, a lot depends on how the 4L80E was rebuilt too.
How does it run at the track and on the street?
Thread Starter
Teching In
Joined: Sep 2017
Posts: 34
Likes: 4
From: Edinboro, PA
What did the vehicle dyno before the new motor? Did the truck have the 4L80E & 3200 stall? Dyno's are best viewed as tuning tools etc.
Who manufactured the 3,200 stall converter? Some are very inefficient. Likewise, a lot depends on how the 4L80E was rebuilt too.
How does it run at the track and on the street?
Who manufactured the 3,200 stall converter? Some are very inefficient. Likewise, a lot depends on how the 4L80E was rebuilt too.
How does it run at the track and on the street?
the only differences are the block (lq4 to ls2), intake manifold (Atomic to Fast), headers (c5 manifolds to 1.75 long tubes), heads (stage 2.5 to ls3)
the converter, I can’t remember who manufactured it. But I imagine it wasn’t anything name brand.
TECH Apprentice
Joined: Feb 2010
Posts: 370
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At what rpm did you make the 319?
what was the torque. Down a cylinder or 2 sounds plausible. Have you put water drops on the hot headers or do you have access to a thermal imager. Are you at a high altitude?
what was the torque. Down a cylinder or 2 sounds plausible. Have you put water drops on the hot headers or do you have access to a thermal imager. Are you at a high altitude?
Last edited by jasons69chevelle; Aug 21, 2022 at 07:20 PM.
Thread Starter
Teching In
Joined: Sep 2017
Posts: 34
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From: Edinboro, PA
you would think that the tuner would notice it down a cylinder. 🤷🏼♂️
I haven’t put water drops on any headers no, and I don’t have an imager. The headers are wrapped in header wrap. How can I test the to see if it’s down a cylinder?
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Teching In
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The rpm was like 5800ish range, I don’t remember the specifics. I didn’t take a picture because I was unimpressed.
you would think that the tuner would notice it down a cylinder. 🤷🏼♂️
I haven’t put water drops on any headers no, and I don’t have an imager. The headers are wrapped in header wrap. How can I test the to see if it’s down a cylinder?
you would think that the tuner would notice it down a cylinder. 🤷🏼♂️
I haven’t put water drops on any headers no, and I don’t have an imager. The headers are wrapped in header wrap. How can I test the to see if it’s down a cylinder?
Just for the sake of clarity, a 25% drivetrain loss with 320whp would be ~425 flywheel, you take the 25% off the flywheel figure to get the wheel figure. That's still less than a stock cammed LS3 so something's definitely up, and something fairly significant.
Thread Starter
Teching In
Joined: Sep 2017
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From: Edinboro, PA
That cam in a 6.0 should be making peak power at least 500rpm higher than that. That's a reasonable amount of lift, you said stock 823s, is that stock springs and pushrods too?
Just for the sake of clarity, a 25% drivetrain loss with 320whp would be ~425 flywheel, you take the 25% off the flywheel figure to get the wheel figure. That's still less than a stock cammed LS3 so something's definitely up, and something fairly significant.
Just for the sake of clarity, a 25% drivetrain loss with 320whp would be ~425 flywheel, you take the 25% off the flywheel figure to get the wheel figure. That's still less than a stock cammed LS3 so something's definitely up, and something fairly significant.
I would like to also state that this is a newly built engine because the last engine i had went to the moon. Similarly, it seemed low on power. It had Richard Holdener's "600HP NA" video cam. Also had PRC stage 2.5 243 heads, milled .020. That engine only made 350whp on what RH said would make almost 600 at flywheel. The cams are pretty similar in profiles.
What happened with that engine was that I was at the track, 1/4 mile, and it would pull hard through 1st and 2nd and then it would start breaking up spitting and sputtering towards the big end. I could let off and get back in and it would go away. The time it blew up I tried to just power through and boom.
I was out driving the corvette the other night and i hit the pedal hard and i felt it do that break up again so i let out. No idea what this issue is.
Im at a point where I might just buy a Holley Terminator harness and ecu because my cut up harness with the stock ecu and hp tuners just seems like its not working right. I also have the EZTCU trans controller and it too sucks. Its always fluctuating between reading the correct TPS signal and not.
Thread Starter
Teching In
Joined: Sep 2017
Posts: 34
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From: Edinboro, PA
Honestly, I dont know. I was an idiot at the time and was not data logging with my HPTuners. I also didnt have an AFR gauge at the time.
But as it is now, I have the gauge and it seems to be at 12-13 when im WOT. I dont know the fuel pressure though.
But as it is now, I have the gauge and it seems to be at 12-13 when im WOT. I dont know the fuel pressure though.
Install a good fuel pressure gauge. Check voltage to the pump at WOT. Get a graph and some data logs. Etc. You're really going to have to do some basic troubleshooting to get anywhere with this.
TECH Fanatic
Joined: Jan 2018
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From: Dade City, Fl.
Go to a good reputable tuner. It will be easy for the tuner to see if it is running out of fuel. You already stated that the fuel system has been upgraded so if the system is working correctly if it is a fueling issue...it's in the tune. If you have access to reading your fuel trims, you should be able to tell if it is leaning out at WOT. (if the commanded fueling is set correctly in the tune)