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Doing a turbo Lm7. Is a rod upgrade in order?

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Old Oct 13, 2013 | 06:01 AM
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Default Doing a turbo Lm7. Is a rod upgrade in order?

Im at the point of putting my piston/rods back in and it keeps coming to mind about the better floating wrist pin rods. Is it really worth it to upgrade? Im shooting for 800-900 whp but not wanting to spend a ton on this 1st motor as its a learning engine and i know its not gonna last long but on the other hand i want it to last more then a couple passes. I plan on build a forged unit after i get this turbo stuff down pat. It's been proven that stock stuff will take some abuse but will the older rods hold up to that hp level? Thanks
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Old Oct 13, 2013 | 06:59 AM
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I'm reading stuff like this http://www.truckinweb.com/tech/engin...g/viewall.html my only option is to say screw it. Put it together. I dont seem to have much input here after 30 some views. so i take it they are ok for minute anyways.
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Old Oct 13, 2013 | 07:42 AM
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Okay, can someone tell me why im getting so many views and zero replies on this question? Im starting to wonder about this place. I have 39 post and not much conversation. Is it a newbie thing?
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Old Oct 13, 2013 | 08:48 AM
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What year is the LM7 from? Planning to go auto or manual trans?
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Old Oct 13, 2013 | 09:07 AM
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The floating wrist pin doesn't mean the engine can handle more power before
the rod breaks. IMO your pistons are the weak link when boosting. I'd open
up the ring end gaps to like .026" primary and .030" secondary and slap it
together. Your tune will have quite an influence on the longevity you acheive.
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Old Oct 13, 2013 | 09:57 AM
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Originally Posted by 2muchboostNY
What year is the LM7 from? Planning to go auto or manual trans?
2001 suburban. It will be an auto car.
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Old Oct 13, 2013 | 10:00 AM
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Originally Posted by A.R. Shale Targa
The floating wrist pin doesn't mean the engine can handle more power before
the rod breaks. IMO your pistons are the weak link when boosting. I'd open
up the ring end gaps to like .026" primary and .030" secondary and slap it
together. Your tune will have quite an influence on the longevity you acheive.
I've been reading its all in the tune. I understand that im gonna be pushing the limit. I just wondered if it was worth the effort to find a set while its apart.
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Old Oct 13, 2013 | 12:54 PM
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If you're going to forge it later anyway, why not do it now while the engine is already out of the car?

Unless you really enjoy pulling the engine out of the car all over again once it does break.
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Old Oct 13, 2013 | 01:24 PM
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Originally Posted by redtan
If you're going to forge it later anyway, why not do it now while the engine is already out of the car?

Unless you really enjoy pulling the engine out of the car all over again once it does break.
I guess because i dont wanna toast 2500 worth of good parts. This is a baseline/test motor for me to learn on. Plus my car is very easy to work on. It takes about 20-30 minutes to pull my motor.
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Old Oct 13, 2013 | 02:54 PM
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Originally Posted by redtan
If you're going to forge it later anyway, why not do it now while the engine is already out of the car?

Unless you really enjoy pulling the engine out of the car all over again once it does break.
See that's the funny thing about the LS series of engines....if the tune is right
Didn't some magazine schlubs make over 1200 horsepower trying to ruin a
legit junkyard engine they originally thought to be a 5.3 only later to find out
that it was a 4.8 (293 cid) ??? At like 28 lbs. of boost the ignition system on
the dyno became the weak link as it was snuffing out the spark....hilarious
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Old Oct 13, 2013 | 05:18 PM
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Originally Posted by A.R. Shale Targa
See that's the funny thing about the LS series of engines....if the tune is right
Didn't some magazine schlubs make over 1200 horsepower trying to ruin a
legit junkyard engine they originally thought to be a 5.3 only later to find out
that it was a 4.8 (293 cid) ??? At like 28 lbs. of boost the ignition system on
the dyno became the weak link as it was snuffing out the spark....hilarious
Yes but he does got me debating on just buying some good rods and pistons.
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Old Oct 13, 2013 | 08:28 PM
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You can get K1 Rods for under 550 from at least 2 vendors... WS6Store and BTR...
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Old Oct 13, 2013 | 08:42 PM
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Originally Posted by JakeFusion™
You can get K1 Rods for under 550 from at least 2 vendors... WS6Store and BTR...
550 seems like a high price after just looking at h-beams being in the mid 300 range.
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Old Oct 13, 2013 | 08:46 PM
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Originally Posted by A.R. Shale Targa
See that's the funny thing about the LS series of engines....if the tune is right
Didn't some magazine schlubs make over 1200 horsepower trying to ruin a
legit junkyard engine they originally thought to be a 5.3 only later to find out
that it was a 4.8 (293 cid) ??? At like 28 lbs. of boost the ignition system on
the dyno became the weak link as it was snuffing out the spark....hilarious
Yes, hot rod did the test. Pretty cool. I agree with A.R., open up the rings and go after it. It's been proven over and over, tune it right, and it'll be fun for a long time!
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Old Oct 13, 2013 | 09:16 PM
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What h-beams are you looking at for mid 300? Even the Scat with 8740 bolts are mid 400s. The Scat I-Beam is that price. I would NOT put that sort of boost on it...

The K1 and Compstar rods are what I'd look at for that power level. Scat and Eagle also make decent rods, but once you step up to ARP2000 bolts, they're the same price as K1/Compstar.
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Old Oct 13, 2013 | 09:25 PM
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Originally Posted by JakeFusion™
What h-beams are you looking at for mid 300? Even the Scat with 8740 bolts are mid 400s. The Scat I-Beam is that price. I would NOT put that sort of boost on it...

The K1 and Compstar rods are what I'd look at for that power level. Scat and Eagle also make decent rods, but once you step up to ARP2000 bolts, they're the same price as K1/Compstar.
Part# H6125 oh and they was 389 sorry
http://www.ohiocrank.com/hbeam_rods.html

Always had good luck with their stuff.
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Old Oct 13, 2013 | 09:28 PM
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You could give them a try. Compstar has probably the best reputation for being able to withstand just about anything you throw at it. The lower end H-Beam they sell is good for 900rwhp. The heavy wall H-Beam or Billet I-Beam are good for like 1200 and 1500 respectively. But they cost a lot more.
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Old Oct 14, 2013 | 01:29 AM
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I had the exact same arguement with myself over and over again, and I have the L33 with the better rods. Folks who know told me the rods are weaker than the peestons, but still good for 800+ whp. Like you, this is a test engine, and I figure I'll find another as soon as one comes available and have it ready to swap in the future, full of the good stuff.
I cleaned everything up real good, re-gapped the rings to .024 top, left the second at .028 and put it together this past weekend.

Good luck with your project!

Ron
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Old Oct 14, 2013 | 07:47 AM
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I would take the suggestions above and re-gap the rings, clean everything up, slap it together, and make sure it has a good tune. If this is your first test mule the extra cash spent on parts and whatever machining can be spent elsewhere. These blocks can be had for sub $500 all day so if by chance you do ruin it its not an expensive endeavor to slap on another block with upgraded internals later on. The tune will be key as everyone pointed out. Look at Denmah's and others builds these things can take a whoopin if tuned properly even if using "cheaper parts" to get everything together.
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Old Oct 14, 2013 | 08:23 AM
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For the price of those forged rods, you can probably pick up another 4.8L/5.3L shortblock. I'd run it, and maybe be more conservative with the power if you want it to last.

You know the saying: CHEAP, FAST, RELIABLE...you can only pick two.
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