LS2 402 Way Low Dyno Numbers. Help Please!
LS2 402 Way Low Dyno Numbers. Help Please! OK guys, I did a really long write-up of my LS2 402 install into my 98 Z28 M6 some time ago. Since then I have been working on the Speed Density tunning and I am confident that I got my VE Tables set properly and my Idle Correct. Today I went and put it on a Dynojet to compare my stock O2 sensor readings to a WBO2. Unfortunately, the shop that I went to does not have the Wideband connected to the dyno (don't ask) so I can't show the fuel curve as I did not get one. I did watch the wideband and saw that the AFR was reading like 12:1 until about 6200 and then started getting rich 11:1 to the 6800-7000RPM rev limiter that I set. I am using HPTuner software. When I took a look at the dyno sheet, I almost threw up right there on the spot even though I could tell that I was not getting the power that I should in the seat of the pants. I really expected just under 500 HP from this setup when I bought it. My problem is that there doesn't seem to be a problem with the way that the car is running. I am not throwing any codes besides the MAF code. The car is not sputtering or missing. There isn't alot of blow-by. Is there something in the tune that I may have messed with that would cost me 100 HP and 80+ torque? I am 
over this. PLEASE HELP ANY SUGGESTIONS ARE WELCOME AS ARE ANY QUESTIONS.
over this. PLEASE HELP ANY SUGGESTIONS ARE WELCOME AS ARE ANY QUESTIONS. Hmmm, wouldn't I be going lean if the injectors were not keeping up? I'm not.
I should be reading between 480 and 500 hp rear wheels with my setup on an M6 and the stock 3.42 gear. This thing should be a major dyno queen. I have never seen a 402 under 440 hp even with an unlocked converter and a 12 bolt with 4.10's.
I should be reading between 480 and 500 hp rear wheels with my setup on an M6 and the stock 3.42 gear. This thing should be a major dyno queen. I have never seen a 402 under 440 hp even with an unlocked converter and a 12 bolt with 4.10's.
Something is definately wrong....You have a fairly large cam (and reverse pattern which Im personally not crazy about) and your TQ peak is occuring around 3600 RPM's. I bet your cam is installed or ground wrong. Do a cranking compression and a leakdown....that would show how well the short is sealed up and if the cam installed position is "close" based on cranking cylinder pressure.
Do this right away....dont even bother with further troubleshooting till you check the condition/status of the shortblock. The good news is that combo is sooo not right, it has to have something seriously wrong that just needs to be un-covered. I wouldn't even be concerned right now....time and patience will ultimately uncover the problem.....and there IS a problem.
Good luck....Keep us posted.
Regards,
Tony M.
Do this right away....dont even bother with further troubleshooting till you check the condition/status of the shortblock. The good news is that combo is sooo not right, it has to have something seriously wrong that just needs to be un-covered. I wouldn't even be concerned right now....time and patience will ultimately uncover the problem.....and there IS a problem.
Good luck....Keep us posted.
Regards,
Tony M.
Last edited by Tony Mamo @ AFR; Apr 6, 2006 at 08:44 PM.
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Originally Posted by DocEwww
SLP built?
Originally Posted by LSs1Power
You need injectors, fuel pump and a dyno that reads A/F to see whats really going on. Also try to put back the MAF and see how the car react. Maybe the SD tune is not working properly.
Faulty lifters...dunno. Incorrect pushrod length I've seen cost people 10-30whp and anything beyond that is grossly audible and you'd know it as soon as you started the car, but that is just from my own experience.
I hope you get it all sorted out. What a bummer, I was reading your post and was thinking, ok...it can't be that bad until I saw the dyno chart. SLP's reverse grind stroker cam power band doesn't look like that, so I'm thinking something mechanical as well.
When I made my first pull on the dyno, I saw the tq curve and got sick to my stomach as well. After looking at the fuel curve and saw that it had pegged at 10.0 to one and was probably richer than that I knew I had some work ahead of me. A grueling 15 pulls later and I was alot closer. However, this is not a tuning issue. Good luck, keep us updated as you did in your buildup. You did a great writeup during the install, it's upsetting to see things didn't turn out right the first time. You'll get it.
dougie
I hope you get it all sorted out. What a bummer, I was reading your post and was thinking, ok...it can't be that bad until I saw the dyno chart. SLP's reverse grind stroker cam power band doesn't look like that, so I'm thinking something mechanical as well.
When I made my first pull on the dyno, I saw the tq curve and got sick to my stomach as well. After looking at the fuel curve and saw that it had pegged at 10.0 to one and was probably richer than that I knew I had some work ahead of me. A grueling 15 pulls later and I was alot closer. However, this is not a tuning issue. Good luck, keep us updated as you did in your buildup. You did a great writeup during the install, it's upsetting to see things didn't turn out right the first time. You'll get it.
dougie
Teching In
Joined: Jan 2006
Posts: 45
Likes: 0
From: Bay Area
We have very similar motors, I believe the problem once discovered will be something pretty simple in the end. I made over 400 pounds of torque at 2500rpm, way above your curve. I doubt injector capacity is your problem, even a stock injector flows enough fuel below 5000 rpm. However, injector model numbers may be inputed into the program incorrectly. Whatever the cause, the dyno sheet really looks like you made the run with a block of wood under the gas pedal.
Chuck
Chuck
Last edited by Chuck Harmon; Apr 7, 2006 at 08:22 PM.
Teching In
Joined: Jan 2006
Posts: 45
Likes: 0
From: Bay Area
As a follow up under the heading of when one assumes...., are you sure the dyno is calibrated properly? How does the car drive? Is traction in 2nd gear non existant? If so, I would suspect the dyno.
Chuck
Chuck
Originally Posted by gtodoug
Faulty lifters...dunno. Incorrect pushrod length I've seen cost people 10-30whp and anything beyond that is grossly audible and you'd know it as soon as you started the car, but that is just from my own experience.
I hope you get it all sorted out. What a bummer, I was reading your post and was thinking, ok...it can't be that bad until I saw the dyno chart. SLP's reverse grind stroker cam power band doesn't look like that, so I'm thinking something mechanical as well.
When I made my first pull on the dyno, I saw the tq curve and got sick to my stomach as well. After looking at the fuel curve and saw that it had pegged at 10.0 to one and was probably richer than that I knew I had some work ahead of me. A grueling 15 pulls later and I was alot closer. However, this is not a tuning issue. Good luck, keep us updated as you did in your buildup. You did a great writeup during the install, it's upsetting to see things didn't turn out right the first time. You'll get it.
dougie
I hope you get it all sorted out. What a bummer, I was reading your post and was thinking, ok...it can't be that bad until I saw the dyno chart. SLP's reverse grind stroker cam power band doesn't look like that, so I'm thinking something mechanical as well.
When I made my first pull on the dyno, I saw the tq curve and got sick to my stomach as well. After looking at the fuel curve and saw that it had pegged at 10.0 to one and was probably richer than that I knew I had some work ahead of me. A grueling 15 pulls later and I was alot closer. However, this is not a tuning issue. Good luck, keep us updated as you did in your buildup. You did a great writeup during the install, it's upsetting to see things didn't turn out right the first time. You'll get it.
dougie
Originally Posted by Chuck Harmon
We have very similar motors, I believe the problem once discovered will be something pretty simple in the end. I made over 400 pounds of torque at 2500rpm, way above your curve. I doubt injector capacity is your problem, even a stock injector flows enough fuel below 5000 rpm. However, injector model numbers may be inputed into the program incorrectly. Whatever the cause, the dyno sheet really looks like you made the run with a block of wood under the gas pedal.
Chuck
Chuck
Originally Posted by Chuck Harmon
As a follow up under the heading of when one assumes...., are you sure the dyno is calibrated properly? How does the car drive? Is traction in 2nd gear non existant? If so, I would suspect the dyno.
Chuck
Chuck
I knew the power was not there when I wasn't blowing cheap bald tires of with a 4K RPM stab of the gas pedal. I don't think that it's the dyno.