408 not making power
-Geoff
-Geoff
TECH Enthusiast
Joined: May 2007
Posts: 538
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can you post up the dyno chart ? to me it sounds like the camshaft might be in way to early or to late. those valve timming events look about spot on for what I have been seeing works with this CI and those heads and intake.
Need some ideas ya'll.... I recently installed an iron 408 in my CTS-V with L92 heads, L76 intake and 236/238 cam with ~.600 lift and 114 LSA. It's not perfectly tuned but is right at 13.0:1 AFR at WOT according to Wideband and is running about 28 degrees Total advance. It's putting 435HP and 405 lbs./ft. of torque to the wheels. This seems WAY low to me according to what else I've seen out there. The motor makes pretty good oil pressure (around 30 lbs. at idle and 52 lbs. at 5000 rpm). It seems to run fine, nothing that would indicate compression or leak down issues... just not what I expected. Any ideas why it could be so off on power?
It does consume about a quart of oil every 1000 miles or so, but with no visible oil smoke out of the exhaust except at WOT high rpm...even then very little.
It does consume about a quart of oil every 1000 miles or so, but with no visible oil smoke out of the exhaust except at WOT high rpm...even then very little.
I agree. Very low even for a less than optimal camshaft.
Thats the only reason I didnt buy the l92 heads for my last 408. Because with my -8cc dish I would be around 10.1 to 1. With the Dart 62cc heads, I went to around 11.2 to 1.
On The Tree
Joined: Jun 2006
Posts: 165
Likes: 0
From: Pendleton, Indiana
To small of a cam, Why does Lingenfelter go with their GT2-2 cams for the stroked LS2's and their new LS3's, I had a LS3 built, Eagle balanced crank, H rod, JE pistons, Dart 225 heads, 112 super charger, Razor alky injection, So on and asked them what would be the best cam and they said right off the bat GT2-2 207/220 571/578 with 1.7 rockers, I have Comp 1.85's....
So my question is why is this cam to small when they are 9 sec. street cars running smaller cams than he has??
So my question is why is this cam to small when they are 9 sec. street cars running smaller cams than he has??
Thread Starter
Teching In
Joined: Jan 2006
Posts: 44
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Guys, you may be right. I just re-checked everything... 4" stroke, 4.030 bore, cometic LS6 head gasket (I think it's .040 thick and 4.060 hole), 70cc chamber (stock L92 unmilled) and an 8cc dish. Harold zero decked the block. Looks to be about 10.66:1. Is that too low? What can I get away with on the street using 93 octance gas without pinging?
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Verdad Gallardo TECH Enthusiast
Joined: May 2007
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While compression can help with TQ output ultimately the most important thing about making Tq is Air volume. the more you have the more Tq you will make. It is possiable that the camshaft is missing the tunning length of the intake manifold runner system hence the low Tq output. Without some dyno charts and more detialed infromation on the problem I do not think anyone here will be able to assist further.
Guys, you may be right. I just re-checked everything... 4" stroke, 4.030 bore, cometic LS6 head gasket (I think it's .040 thick and 4.060 hole), 70cc chamber (stock L92 unmilled) and an 8cc dish. Harold zero decked the block. Looks to be about 10.66:1. Is that too low? What can I get away with on the street using 93 octance gas without pinging?
Have you tried ripping other tunes to your engine? I was having some problems similar to that, i got p&p ls1 heads, and a 232/232 cam, i am putting 450/475 on paper. If you want i can send you my tune. Also, on HPT website, there is a rip from a 1999 z28 with a 408 with texas speed tune for m6, rip that one to see how it runs, just my input
Need some ideas ya'll.... I recently installed an iron 408 in my CTS-V with L92 heads, L76 intake and 236/238 cam with ~.600 lift and 114 LSA. It's not perfectly tuned but is right at 13.0:1 AFR at WOT according to Wideband and is running about 28 degrees Total advance. It's putting 435HP and 405 lbs./ft. of torque to the wheels. This seems WAY low to me according to what else I've seen out there. The motor makes pretty good oil pressure (around 30 lbs. at idle and 52 lbs. at 5000 rpm). It seems to run fine, nothing that would indicate compression or leak down issues... just not what I expected. Any ideas why it could be so off on power?
It does consume about a quart of oil every 1000 miles or so, but with no visible oil smoke out of the exhaust except at WOT high rpm...even then very little.
It does consume about a quart of oil every 1000 miles or so, but with no visible oil smoke out of the exhaust except at WOT high rpm...even then very little.
I was runnig a similar cam (slightly bigger) and putting down around 470/455 to the wheels. Added a catch can set up (search "see5" posts) which eliminated the oil consumption issue. Car is at ICON right now getting a bigger cam put in along with some kooks 1 7/8's headers. I expect alot more this time around.. Will let ya know.
There may be a little left in the tune. Theres ways of figuring out if your comp is low too, without pull the motor apart.
https://ls1tech.com/forums/dynamometer-results-comparisons/802086-thank-you-ed-hutchings.html
https://ls1tech.com/forums/dynamometer-results-comparisons/802086-thank-you-ed-hutchings.html
This seems alot like the issues I was having with my 402. L92/L76 etc..
I was runnig a similar cam (slightly bigger) and putting down around 470/455 to the wheels. Added a catch can set up (search "see5" posts) which eliminated the oil consumption issue. Car is at ICON right now getting a bigger cam put in along with some kooks 1 7/8's headers. I expect alot more this time around.. Will let ya know.
I was runnig a similar cam (slightly bigger) and putting down around 470/455 to the wheels. Added a catch can set up (search "see5" posts) which eliminated the oil consumption issue. Car is at ICON right now getting a bigger cam put in along with some kooks 1 7/8's headers. I expect alot more this time around.. Will let ya know.
Last edited by edcmat-l1; Oct 22, 2007 at 07:04 AM.
Thread Starter
Teching In
Joined: Jan 2006
Posts: 44
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I wondering now if the pushrods I had for my LS6 heads, which I'm now using on the L92s, are too short. Something tells me I'm not getting all the lift at the valve that I should be. Or, maybe the CTSV-R lifters are shorter or the base circle of my cam is shorter? Anyone else ever experience one of these things? The car doesn't feel like it's down a cylinder, I'm pretty in tune with the sound and feel of 8 cylinders vs. 7.
Agree that there is more power potential in the tune...just not 60-70 horsepower and that much more torque. Something else must be wrong.
The catch can is a great idea for stopping the oil burning through the intake...I'll have to try that. Maybe the intake charge is severely polluted with that much oil going through there? I'M PULLING MY HAIR OUT!!! ARGHHHHHHHH!!!
Agree that there is more power potential in the tune...just not 60-70 horsepower and that much more torque. Something else must be wrong.
The catch can is a great idea for stopping the oil burning through the intake...I'll have to try that. Maybe the intake charge is severely polluted with that much oil going through there? I'M PULLING MY HAIR OUT!!! ARGHHHHHHHH!!!
I am far from an expert.. In my 402/L76/L92 motor, I just used the cam out of my 427. It is a 240/240 @.050, .608/.608 w/114. With 11.5 cr, I make 502/476 thru my A4..
The cam can make a difference. Thats alot of difference though.. If all is assembled right, I would try loading up a different tune before I start messing with the motor..
JMHO
The cam can make a difference. Thats alot of difference though.. If all is assembled right, I would try loading up a different tune before I start messing with the motor..
JMHO
Need some ideas ya'll.... I recently installed an iron 408 in my CTS-V with L92 heads, L76 intake and 236/238 cam with ~.600 lift and 114 LSA. It's not perfectly tuned but is right at 13.0:1 AFR at WOT according to Wideband and is running about 28 degrees Total advance. It's putting 435HP and 405 lbs./ft. of torque to the wheels. This seems WAY low to me according to what else I've seen out there. The motor makes pretty good oil pressure (around 30 lbs. at idle and 52 lbs. at 5000 rpm). It seems to run fine, nothing that would indicate compression or leak down issues... just not what I expected. Any ideas why it could be so off on power?
It does consume about a quart of oil every 1000 miles or so, but with no visible oil smoke out of the exhaust except at WOT high rpm...even then very little.
It does consume about a quart of oil every 1000 miles or so, but with no visible oil smoke out of the exhaust except at WOT high rpm...even then very little.
Take it to a professional tuner.
I wondering now if the pushrods I had for my LS6 heads, which I'm now using on the L92s, are too short. Something tells me I'm not getting all the lift at the valve that I should be. Or, maybe the CTSV-R lifters are shorter or the base circle of my cam is shorter? Anyone else ever experience one of these things? The car doesn't feel like it's down a cylinder, I'm pretty in tune with the sound and feel of 8 cylinders vs. 7.
Agree that there is more power potential in the tune...just not 60-70 horsepower and that much more torque. Something else must be wrong.
The catch can is a great idea for stopping the oil burning through the intake...I'll have to try that. Maybe the intake charge is severely polluted with that much oil going through there? I'M PULLING MY HAIR OUT!!! ARGHHHHHHHH!!!
Agree that there is more power potential in the tune...just not 60-70 horsepower and that much more torque. Something else must be wrong.
The catch can is a great idea for stopping the oil burning through the intake...I'll have to try that. Maybe the intake charge is severely polluted with that much oil going through there? I'M PULLING MY HAIR OUT!!! ARGHHHHHHHH!!!