Question on Forged piston/rod combo.
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TECH Resident
Joined: Aug 2003
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From: orlando, florida
Question on Forged piston/rod combo. I was trying to figure out what would happen if you used a piston that was designed for a 6.125 rod with a stock 6.098 ls1 rod. I'm assuming it would lower compression but what else would it affect and how much?
I'm running a set of lunati NHRA flat tops with stock rods machined for floating wrist pins. My question is since my enbine builder opted for the .928 wrist pin are my pistons designed to run with the longer rods or the stock rods? i'm getting ready to replace the stock rods with a forged set but I need to figure out if i should go with a stock length rod or a longer rod. I'd like to try to stick with somthing that will work with the lunati pistons i'm running now since I really like these pistons and they've held up to some unreal punishment.
But on the other hand I recently learned that the shop that built the engine is not very good at what they do and that got me thinking about how well built my engine is. Like for instance i'm running a 98 block that has been honed out but it's still running the stock size pistons, the engine has always been real loud. I wonder if the engine needs a 3.903 piston instead of the 3.898, which would also explain why my rings are already shot after only 10K miles.
Please give me your opinions on how I should go about this rebuild. Should I start over with new pistons/Rods or should I just replace the rods?
My other dilema is what rods to go with if I stick with stock length I'm pushing 650crank HP on the stock rods no problem. Most of the aftermarket rods aren't rated much higher then that and i'm not spending $1000 on a set of billit rods.
Sorry for the novel.
I'm running a set of lunati NHRA flat tops with stock rods machined for floating wrist pins. My question is since my enbine builder opted for the .928 wrist pin are my pistons designed to run with the longer rods or the stock rods? i'm getting ready to replace the stock rods with a forged set but I need to figure out if i should go with a stock length rod or a longer rod. I'd like to try to stick with somthing that will work with the lunati pistons i'm running now since I really like these pistons and they've held up to some unreal punishment.
But on the other hand I recently learned that the shop that built the engine is not very good at what they do and that got me thinking about how well built my engine is. Like for instance i'm running a 98 block that has been honed out but it's still running the stock size pistons, the engine has always been real loud. I wonder if the engine needs a 3.903 piston instead of the 3.898, which would also explain why my rings are already shot after only 10K miles.
Please give me your opinions on how I should go about this rebuild. Should I start over with new pistons/Rods or should I just replace the rods?
My other dilema is what rods to go with if I stick with stock length I'm pushing 650crank HP on the stock rods no problem. Most of the aftermarket rods aren't rated much higher then that and i'm not spending $1000 on a set of billit rods.
Sorry for the novel.
I have a set of Manley forged rods (#14106, 6.1" w/.928 floating pins) that go with those pistons - $450 plus shipping - PM me if you are interested.
I have a set of the Lunati NHRA pistons too if you need any replacements - $200 plus shipping.
As far as the combination - sounds like maybe the machine shop honed the block a little too much (it does need honed a little to get good wall clearances with Lunati pistons, but maybe they overdid it).
One option would be finding another good stock bore block and putting together another one. I have actually been hanging onto the pistons, rods, and a crank that I have with that in mind - but I could use some cash and will sell them.
I have a set of the Lunati NHRA pistons too if you need any replacements - $200 plus shipping.
As far as the combination - sounds like maybe the machine shop honed the block a little too much (it does need honed a little to get good wall clearances with Lunati pistons, but maybe they overdid it).
One option would be finding another good stock bore block and putting together another one. I have actually been hanging onto the pistons, rods, and a crank that I have with that in mind - but I could use some cash and will sell them.
Last edited by BLK02WS6; Aug 10, 2004 at 04:20 PM.
Thread Starter
TECH Resident
Joined: Aug 2003
Posts: 948
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From: orlando, florida
Thanks guys. 
I'll remember this the next time any off you need help.
Thanks BLK02WS6, I'll have to research alittle more on them rods. I wonder if they'll work since there a bit longer then the stock ones?
I'll remember this the next time any off you need help.
Thanks BLK02WS6, I'll have to research alittle more on them rods. I wonder if they'll work since there a bit longer then the stock ones?
Originally Posted by MYTURBOT/A
Thanks BLK02WS6, I'll have to research alittle more on them rods. I wonder if they'll work since there a bit longer then the stock ones?
BTW, the engine only had about 5k miles on it. I took it apart because the machine shop that built it made the clearances too loose on the mains and I had oil pressure that was lower than I wanted (20psig at idle). I fought with them about it, but they wouldn't stand behind it and tighten up the bearings - so I built my current 6.0L and figured I would part it out or hold on to the parts for a rebuild later.
Anyway, let me know if you are interested.
