LQ9 went boom. Lack of meth to blame?
#1
LQ9 went boom. Lack of meth to blame?
This is my first post here, but have been posting on the Silverado Sierra forum.
I have a 2005 Silverado SS with a 406 stroker and forged internals with an s485.
I am running a TBSS intake, and spraying around 16gph pre TB. I had it tuned in 91 with the methanol.
I started hearing some knocking so decided to pull the engine. Cylinder 7 was trashed with a broken piston. It shared some stuff with 5 and beat it up too. My current theory is that meth couldn’t make it to the back cylinder and it got hotter than the other, pinched the ring a bunch and it found the weak spot in the piston which was the valve relief. I bought a 4 corner steam kit, and a sheet metal intake.
Does that theory sound plausible? Haven’t torn down the bottom end yet but I suspect a bearing too. I’m unsure if you can add extra fuel per cylinder in HPTuners, but what my biggest question was is regarding meth. Can I spray pre-tb to cool down the air and get a reading from the IAT sensor, and also spray on top in the middle or more of a port injection style for more fuel? Or will I just run into the same problem? I’m a VW guy and this is my first V8 so I appreciate the help. Thanks!
I have a 2005 Silverado SS with a 406 stroker and forged internals with an s485.
I am running a TBSS intake, and spraying around 16gph pre TB. I had it tuned in 91 with the methanol.
I started hearing some knocking so decided to pull the engine. Cylinder 7 was trashed with a broken piston. It shared some stuff with 5 and beat it up too. My current theory is that meth couldn’t make it to the back cylinder and it got hotter than the other, pinched the ring a bunch and it found the weak spot in the piston which was the valve relief. I bought a 4 corner steam kit, and a sheet metal intake.
Does that theory sound plausible? Haven’t torn down the bottom end yet but I suspect a bearing too. I’m unsure if you can add extra fuel per cylinder in HPTuners, but what my biggest question was is regarding meth. Can I spray pre-tb to cool down the air and get a reading from the IAT sensor, and also spray on top in the middle or more of a port injection style for more fuel? Or will I just run into the same problem? I’m a VW guy and this is my first V8 so I appreciate the help. Thanks!
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strutaeng (04-08-2023)
#4
I’ve never heard of not tuning for meth. Straight water, sure, but all my other cars have all been tuned to account for the octane boost. Twin 450 pumps through -8 everything, 1000cc injectors. I didn’t build this motor, and the guy who had it before me also blew it, which is why they took it out .020.
#5
I installed twin 450’s through Holley -8 lines. Was running around 14psi and was waiting for e85 tune to turn it up. I’d guess maybe 650-700 on butt Dyno.
#6
I just got the rods out. The previous owner installed ARP main bolts and did not have it line honed. I don’t think that that was the main reason, but it definitely did not help. There is not a single bearing that I would consider throwing back into a stock truck. The crank catches my fingernail where every single bearing was, some less than others.
Compression was lowered with the rods, and all of the pistons have more wear than I would expect from a 2000 mile build. I saw paperwork confirming that everything was new, and mileage was confirmed from the invoice for the built 4l80. This engine never had a chance.
Compression was lowered with the rods, and all of the pistons have more wear than I would expect from a 2000 mile build. I saw paperwork confirming that everything was new, and mileage was confirmed from the invoice for the built 4l80. This engine never had a chance.
#7
TECH Junkie
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#8
#9
TECH Junkie
That’s what I thought. That skirt wear does not surprise me with shorter rods intended for lowering compression. Any 4” stroke LQx is already going to encounter some decent piston rocking and skirt wear.
You need to pick the correct piston for rod length. A rod requires Z piston whereas B rod requires Y. I am sure you know this already but yes, that engine never stood a chance.
You need to pick the correct piston for rod length. A rod requires Z piston whereas B rod requires Y. I am sure you know this already but yes, that engine never stood a chance.
#10
That’s what I thought. That skirt wear does not surprise me with shorter rods intended for lowering compression. Any 4” stroke LQx is already going to encounter some decent piston rocking and skirt wear.
You need to pick the correct piston for rod length. A rod requires Z piston whereas B rod requires Y. I am sure you know this already but yes, that engine never stood a chance.
You need to pick the correct piston for rod length. A rod requires Z piston whereas B rod requires Y. I am sure you know this already but yes, that engine never stood a chance.