LS2 402 Way Low Dyno Numbers. Help Please!
04-08-2006, 09:04 AM
#21
Could a problem with the TPS cause a low power condition?
I have thrown a couple of codes with regards to voltage or something.
Could I take the TB off my 04 GTO and just swap it using the sensor in the newer one? Is it compatible mechanically (I know that it is) and electronically ?
I have thrown a couple of codes with regards to voltage or something.
Could I take the TB off my 04 GTO and just swap it using the sensor in the newer one? Is it compatible mechanically (I know that it is) and electronically ?
04-08-2006, 04:28 PM
#22
I found a P0121 code and I disabled the TPS test as noted in the description on the HPTuners software. LTFTs all went way positive and I adjusted it. The funny thing is that know my LTFT's and STFT's are all 0. This would be ok if it wasn't for the fact that they are ALL ZERO. They were reading positive but I haven't seen one even jump into the negative for a second. Any idears?
The car is running very smooth though. Feels a little stronger maybe 10-20 HP. It might just be because it is more responsive right now.
The car is running very smooth though. Feels a little stronger maybe 10-20 HP. It might just be because it is more responsive right now.
04-09-2006, 02:02 PM
#25
Tony or any other knowledgeable person out there that may be reading this,
I have not had an opportunity to do a leak down test yet. I was supposed to go over to a buddies house today to do it but we had some miscommunication and that does not appear to be happening today. So instead of just sitting here and sulking about it, I decided to pull the valve covers as I strongly believe that the problem is living in my valvetrain. I did not check the pushrod length and instead just put a 7.4 pushrod that was recommended by the company that sold me the heads, cam and shortblock. I searched and read a post in which Tony explains how to check the pushrod length. So, I am currently looking at the drivers side rockers and they all have enough wiggle room to were they will tick except for one that appears to be holding the valve open. That one has no play at all. Is this normal or should there be no play in any of them. When I say "play" I mean that they can be rocked side to side but the rockers are firmly against the pushrods on one side and firmly against the valve stem on the other side. These are stock rockers on the rail.
I have not had an opportunity to do a leak down test yet. I was supposed to go over to a buddies house today to do it but we had some miscommunication and that does not appear to be happening today. So instead of just sitting here and sulking about it, I decided to pull the valve covers as I strongly believe that the problem is living in my valvetrain. I did not check the pushrod length and instead just put a 7.4 pushrod that was recommended by the company that sold me the heads, cam and shortblock. I searched and read a post in which Tony explains how to check the pushrod length. So, I am currently looking at the drivers side rockers and they all have enough wiggle room to were they will tick except for one that appears to be holding the valve open. That one has no play at all. Is this normal or should there be no play in any of them. When I say "play" I mean that they can be rocked side to side but the rockers are firmly against the pushrods on one side and firmly against the valve stem on the other side. These are stock rockers on the rail.
04-09-2006, 02:48 PM
#27
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I wouldn't count out the possibility of valve float/bounce too. I know the beehive springs do a great job of counteracting float, but with your cam as big as it is your valves may not be snapping shut quickly enough, or may be skipping on their seats.
04-09-2006, 03:19 PM
#28
assembled heads were purchased with the cam. They are supposed to be setup to work together.
Can anyone tell me about the rockers? Is there supposed to be some play in the ones that aren't holding the valves open? Side to side play I mean. please see my previous post.
Can anyone tell me about the rockers? Is there supposed to be some play in the ones that aren't holding the valves open? Side to side play I mean. please see my previous post.
04-10-2006, 09:28 AM
#30
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When my engine was first installed I had pushrods that were too short, the valve train sounded like a 1970 LT1. I'm sure I was down on power before I changed them, but the car still shredded the tires in 2nd gear. As you said, I also doubt valve float since you power is down across the whole curve. As a matter of fact it looks almost exactly like an unmodified LS6. Are you sure they gave you the 64cc heads and not the low compression 72cc heads?
Chuck
Chuck
04-10-2006, 03:33 PM
#31
They dont offer a 72cc head so they are sure that the heads are right. I did a compression test and am getting 118-122 psi on all cylinders. I have not been able to do the leakdown test yet. I got the gage just don't have a compressor here YET. Anyway, I pulled the plugs and found that they don't look the same. What would cause them to have what appears to be different Air Fuel Ratios ?
The one on the bottom left is the number 1 cylinder and they are in the correct order. Any thoughts? I did find that the little screw on heads were lose in a bunch of them. Would this hurt anything?
The one on the bottom left is the number 1 cylinder and they are in the correct order. Any thoughts? I did find that the little screw on heads were lose in a bunch of them. Would this hurt anything?
04-10-2006, 03:52 PM
#32
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You appear to be right in that SLP no longer shows the 72cc LS1 heads on their web site; but, they were definately selling them 60 days ago. I can get you the part number and description from the catalog they enclosed with my heads if you like. Your cranking numbers also seem low to me. I thought mine were closer to 190+ 5 pounds. I you do have lower compression heads with your longer duration cam, that could explain things.
Chuck
Chuck
04-10-2006, 05:16 PM
#33
I think that the compression is fine. I just did my buddies compression with the same gage and got the same exact values out of his ls2 402 that makes 520 Rwhp. I think that the number 6 and 7 plugs aren't firing correctly. That could rob 100 hp. Just not sure why they aren't firing correctly and how would I have not thrown a code? I have to check my tune to make sure that the misfire code is not shut off. It does look like those 2 aren;t fire correctly, right? Is this just wishfull thinking on my part?
04-10-2006, 05:41 PM
#34
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Originally Posted by 98Z28CobraKiller
I think that the compression is fine. I just did my buddies compression with the same gage and got the same exact values out of his ls2 402 that makes 520 Rwhp. I think that the number 6 and 7 plugs aren't firing correctly. That could rob 100 hp. Just not sure why they aren't firing correctly and how would I have not thrown a code? I have to check my tune to make sure that the misfire code is not shut off. It does look like those 2 aren;t fire correctly, right? Is this just wishfull thinking on my part?
if you and your buddy are both getting 122psi pressure, then you need to change your gauge you are using for testing. That is wayyyyyy low. Thats a broken cylinder almost.
I would expect you to be in the 170-180 range with that camshaft. That would explain why you are down on power. I would highly suggest checking your camshaft and checking how its installed.
Compression is your friend.
04-10-2006, 05:42 PM
#35
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Also, if your camshaft is that far off from the ICL it was ground on, you could be having the issues you are having with the plugs looking lke that. Just nothing much to ignite.
Rick
Rick
04-10-2006, 06:15 PM
#36
He's not running the same camshaft. He is running less duration (like 24X) and less lift (like 56X) and a different lsa (like 110). Would that give higher or lower compression values? If the cam was way off, would that lower my values also? I was told that there was a way to check the cam without taking the front cover off. I am going to read up on that and check the degreeing on the cam.
04-10-2006, 06:29 PM
#37
NOT "acceptable".... Cranking CR is Waaaaay off.
Even with a big cam, (assuming anywhere close to 11 to 1 static), you should be at LEAST 150-160 lbs. My 383 at 11.0 to one has around 185-190 lbs. with a medium sized 242-248 solid roller (which would act like a hyd. roller approx. 236/242).
Don't dismiss that low CCR as "OK"....its not and is the reason I inquired about it in the first place. I bet the cam is in wrong....that would be on top of the pile of reasons that could show a screwed up dyno curve and the low cranking results. Also, can you back up those numbers on another CR tester or do you know the one you are using is accurate?? Assuming it is, I would start working on getting to that cam and throwing a degree wheel on it which I have a hunch wasn't done the first go around. Find out exactly where it is installed and /or if by some remote chance it wasn't ground right.
Another good thread that indirectly stresses the importance of degree wheels and extra time in pre-assembly. Assuming the cam was degreed in, we would have to rule it out of the possibilities of cam installation potentially being the culprit to our problem. It's easy to be a tooth off if the install was done in the vehicle.
Any other clues as to whats going on?....your plugs dont look perfect but they aren't the answer to this, especially considering the CCR results.
Keep us posted...
Tony M.
Even with a big cam, (assuming anywhere close to 11 to 1 static), you should be at LEAST 150-160 lbs. My 383 at 11.0 to one has around 185-190 lbs. with a medium sized 242-248 solid roller (which would act like a hyd. roller approx. 236/242).
Don't dismiss that low CCR as "OK"....its not and is the reason I inquired about it in the first place. I bet the cam is in wrong....that would be on top of the pile of reasons that could show a screwed up dyno curve and the low cranking results. Also, can you back up those numbers on another CR tester or do you know the one you are using is accurate?? Assuming it is, I would start working on getting to that cam and throwing a degree wheel on it which I have a hunch wasn't done the first go around. Find out exactly where it is installed and /or if by some remote chance it wasn't ground right.
Another good thread that indirectly stresses the importance of degree wheels and extra time in pre-assembly. Assuming the cam was degreed in, we would have to rule it out of the possibilities of cam installation potentially being the culprit to our problem. It's easy to be a tooth off if the install was done in the vehicle.
Any other clues as to whats going on?....your plugs dont look perfect but they aren't the answer to this, especially considering the CCR results.
Keep us posted...
Tony M.
04-10-2006, 08:44 PM
#38
Here's a picture of the front of the motor w/o the front cover on it. No I did not degree the cam. I just figured that dot to dot would be ok. I guess that's the most likely culprit here 
. It seemed like such a time saver at the time. Know I have to do it bent over the freaking car. Does the radiator have to come out?
. It seemed like such a time saver at the time. Know I have to do it bent over the freaking car. Does the radiator have to come out?
04-10-2006, 11:39 PM
#39
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No such thing as a time saver. If you want to save time, spend time in the first place, because now time is your enemy. Like Tony said, low compression is bad. That means no TQ. TQ is HP, always has been, always will be.
Why the big cam anyways? Sorry to be off topic. What compression is the motor supposed to be?
Rick
Why the big cam anyways? Sorry to be off topic. What compression is the motor supposed to be?
Rick
04-10-2006, 11:42 PM
#40
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Here is something else for you as well.
I see you still have an LS6 manifold on there, thats good to a point. Here is something I saw latley with a car on the dyno.
It was a 402 as well. Had a 226/226 112 cam in it and made 490TQ and 473hp. Killer setup. Customer wanted a 230/234 114 cam, guess what happened? He lost TQ and HP. Why? The motor was already maxed out. The engine could not physically take in anymore air. So all that happened was compression became lower now due to more duration. So this could be something you are also facing in this build, way tooooo much camshaft. Not enough cylinder pressure.
Rick
I see you still have an LS6 manifold on there, thats good to a point. Here is something I saw latley with a car on the dyno.
It was a 402 as well. Had a 226/226 112 cam in it and made 490TQ and 473hp. Killer setup. Customer wanted a 230/234 114 cam, guess what happened? He lost TQ and HP. Why? The motor was already maxed out. The engine could not physically take in anymore air. So all that happened was compression became lower now due to more duration. So this could be something you are also facing in this build, way tooooo much camshaft. Not enough cylinder pressure.
Rick