Burnt a piston in my LQ4, gonna try same setup with a 5.3 to compare
10-26-2012, 10:06 AM
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Burnt a piston in my LQ4, gonna try same setup with a 5.3 to compare I decided to make my own thread on this topic to do a comparison. I'm going to paste the relevant info and comments from the other thread found here:
https://ls1tech.com/forums/forced-in...h-boost-3.html
Original post:
About a week and a half ago I burnt a piston in my JY 6.0. The fastest it went was 10.75 @ 131 in my 3600# cutlass. I'm gonna swap to a JY 5.3 with the same exact setup and compare the two.
Mods:
LS6 cam
Springs & pushrods to match
Victor Jr intake
750 blow thru carb
Garrett GT42-94R
Open 4" downpipe about 5 feet long.
It went 10.75 with a powerglide, car now has a th400
Anyone care to venture a guess of if I will gain or lose ET?
https://ls1tech.com/forums/forced-in...h-boost-3.html
Original post:
About a week and a half ago I burnt a piston in my JY 6.0. The fastest it went was 10.75 @ 131 in my 3600# cutlass. I'm gonna swap to a JY 5.3 with the same exact setup and compare the two.
Mods:
LS6 cam
Springs & pushrods to match
Victor Jr intake
750 blow thru carb
Garrett GT42-94R
Open 4" downpipe about 5 feet long.
It went 10.75 with a powerglide, car now has a th400
Anyone care to venture a guess of if I will gain or lose ET?
Get that 60' down and you shouldn't lose any e.t. My 4200lb truck ran 10.97 @ 125 with a 5.3 and baby on3 turbo.
There is no reason to go with a 6.0 with the power these 5.3's are making. You can buy 3 for the price of one 6.0. That 7675 would be perfect for a 5.3 and has the capability to make 900rwhp.
There is no reason to go with a 6.0 with the power these 5.3's are making. You can buy 3 for the price of one 6.0. That 7675 would be perfect for a 5.3 and has the capability to make 900rwhp.
10-26-2012, 10:16 AM
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Some info on the turbo:
Ball bearing Garrett GT42-94R
Compressor Specs:
Inducer = 70.3mm
Exducer = 94mm
Trim = 56
AR = 0.60
Turbine Specs:
Wheel dia = 82mm
Trim = 84
AR = 1.44 T6 flange
The exhaust housing comes with a 5" vband outlet. I welded a 4" vband to the inside of that so I could run a open 4" down pipe.
I had two 4" diesel glass pack style mufflers on it at one point. This added in the ball park of 65# and turned out to be extremely restrictive. I lost 6mph in the 1/8th by just adding this exhaust.
I think the above point really illustrates the fact that the 6.0 was waaaaay to big for this turbo. It would run out of breath at 5700 and was struggling to get to 6000 where I shifted.
I don't think that the 5.3 will make more power in EVERY case, especially when the turbo is spec'd for the engine....BUT I think that swapping to a 5.3 will pick up power and ET in my case because of how the lower displacement will be easier to move through that exhaust turbine.
Ball bearing Garrett GT42-94R
Compressor Specs:
Inducer = 70.3mm
Exducer = 94mm
Trim = 56
AR = 0.60
Turbine Specs:
Wheel dia = 82mm
Trim = 84
AR = 1.44 T6 flange
The exhaust housing comes with a 5" vband outlet. I welded a 4" vband to the inside of that so I could run a open 4" down pipe.
I had two 4" diesel glass pack style mufflers on it at one point. This added in the ball park of 65# and turned out to be extremely restrictive. I lost 6mph in the 1/8th by just adding this exhaust.
I think the above point really illustrates the fact that the 6.0 was waaaaay to big for this turbo. It would run out of breath at 5700 and was struggling to get to 6000 where I shifted.
I don't think that the 5.3 will make more power in EVERY case, especially when the turbo is spec'd for the engine....BUT I think that swapping to a 5.3 will pick up power and ET in my case because of how the lower displacement will be easier to move through that exhaust turbine.
10-26-2012, 10:23 AM
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Another factor to consider:
My car went a best of 10.75 @ 131 with a powerglide off of a 1.80 sixty.
Even after replicating that 60' with a th400 it wouldnt run better than 11.00's.
At one point I put on a set of 26" slicks and had a 1.60. But the car was several mph off due to the mufflers I had added that week. Even so, I doubt it would have run the same ET as it had with the glide.
I believe the reason for this is that I was in the mid rpm torque for much longer with the glide rather than the higher rpm with the th400 where the turbo couldn't keep up with the exhaust demands of the 6.0
My car went a best of 10.75 @ 131 with a powerglide off of a 1.80 sixty.
Even after replicating that 60' with a th400 it wouldnt run better than 11.00's.
At one point I put on a set of 26" slicks and had a 1.60. But the car was several mph off due to the mufflers I had added that week. Even so, I doubt it would have run the same ET as it had with the glide.
I believe the reason for this is that I was in the mid rpm torque for much longer with the glide rather than the higher rpm with the th400 where the turbo couldn't keep up with the exhaust demands of the 6.0
10-26-2012, 10:41 AM
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I guess I should have made some kind of comment about why it burnt a piston....
I believe the float level was low in the carb. I also swapped I truck thermostat in for the restrictor I had before that. The car got very hot during that pass and may have been boiling the fuel in the bowls. The previous pass before it torched the piston it was a little rich, then the next pass it nosed over around 1000' and I looked at the wideband to see 14.3 when I lifted.
I do plan to address the obious issue with the tune.
10-26-2012, 10:54 AM
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I don't know which will be better but I can come get the 6.0 today if the buyer falls through. I sold my 408 and I'm going turbo. With a forged rod and piston 6.0.
