Affordable light rotating assembly
03-14-2018, 09:44 PM
#1
Burning Brakes
Thread Starter
Affordable light rotating assembly
I need to rebuild my NA LS7. Rods and crank are not reusable and I want to add forged pistons. Plus I was told you can't remove the pistons from the stock rods without drilling a hole in them. I know this has been discussed a bit recently but has anyone found a crank, rod, and piston setup that won't rob me of power? I'd like to shed weight if possible but at least keep weights similar to stock. Stock rods seem to have questionable reliability thanks to rod to rod wear so using stock rods again scares me a bit. If I do use stock rods I'm planning on running ones that have had their big ends coated by calico and then maybe they'll last. Spring is almost here so I don't have time for any custom parts.
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SivaSuryaKshatriya (03-29-2022)
03-14-2018, 10:16 PM
#2
Safety Car
Member Since: Nov 2005
Location: Lompoc, CA. Santa Barbara County
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I need to rebuild my NA LS7. Rods and crank are not reusable and I want to add forged pistons. Plus I was told you can't remove the pistons from the stock rods without drilling a hole in them. I know this has been discussed a bit recently but has anyone found a crank, rod, and piston setup that won't rob me of power? I'd like to shed weight if possible but at least keep weights similar to stock. Stock rods seem to have questionable reliability thanks to rod to rod wear so using stock rods again scares me a bit. If I do use stock rods I'm planning on running ones that have had their big ends coated by calico and then maybe they'll last. Spring is almost here so I don't have time for any custom parts.
Bee Jay
03-14-2018, 10:24 PM
#3
Burning Brakes
Thread Starter
I'm not sure there is anything off the shelf but I thought I'd ask one last time before using my new stock crank and coated stock rods. I think this rod rubbing issue is more common than most people think and is not totally specific to any one year. Granted I seemed to have some sort of oiling issue based off the damage I found throughout.
Last edited by rio95; 03-14-2018 at 10:25 PM.
03-15-2018, 12:10 AM
#4
Safety Car
Member Since: Nov 2005
Location: Lompoc, CA. Santa Barbara County
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I'm not sure there is anything off the shelf but I thought I'd ask one last time before using my new stock crank and coated stock rods. I think this rod rubbing issue is more common than most people think and is not totally specific to any one year. Granted I seemed to have some sort of oiling issue based off the damage I found throughout.
03-15-2018, 12:14 AM
#5
Burning Brakes
Thread Starter
What's funny is the rod bearings and bushing were pretty much the only things that were good in my shortblock. Main bearings, cam bearings, crank, and rods were bad. At least I found out where all the glitter came from and why my oil pressure dropped. I'll be deleting my oil cooler, switching oils, and keep the oil topped off at all times this time around.
03-15-2018, 02:04 AM
#6
Any rod besides aluminum/ti is going to be heavier. I found these in the past, don't know if the company is gtg or not.
https://store.custombuiltmotors.com/...25---4130.html
could ask to swap to a JE piston or no piston included.
https://store.custombuiltmotors.com/...25---4130.html
could ask to swap to a JE piston or no piston included.
03-15-2018, 09:44 AM
#8
Burning Brakes
Thread Starter
I'm currently planning on running the off the shelf Mahle pistons after my builder measures the cylinders and rod bushings. Guess I have that going for me.
03-15-2018, 09:59 AM
#9
Le Mans Master
Affordable is the OP operative word.
I'd think that means he is ruling out titanium.
So for lightness, and I am not an expert in writing this, I would balance all the OEM piston/ rod assembles to the lightest one and perhaps "knife" the crank.
Not sure what other option would fall under affordable.
Good luck with your build.
I'd think that means he is ruling out titanium.
So for lightness, and I am not an expert in writing this, I would balance all the OEM piston/ rod assembles to the lightest one and perhaps "knife" the crank.
Not sure what other option would fall under affordable.
Good luck with your build.
03-15-2018, 11:06 AM
#10
Burning Brakes
Thread Starter
Affordable is the OP operative word.
I'd think that means he is ruling out titanium.
So for lightness, and I am not an expert in writing this, I would balance all the OEM piston/ rod assembles to the lightest one and perhaps "knife" the crank.
Not sure what other option would fall under affordable.
Good luck with your build.
I'd think that means he is ruling out titanium.
So for lightness, and I am not an expert in writing this, I would balance all the OEM piston/ rod assembles to the lightest one and perhaps "knife" the crank.
Not sure what other option would fall under affordable.
Good luck with your build.
03-15-2018, 02:17 PM
#12
Burning Brakes
So, the question is: what is the reason/cause behind the rubbing?
Incorrect clearances?
Thats the bottom line.
Without the extra expense of going semi-exotic (which the stock assembly is) you will be lucky to find anything lighter and cheaper.
Incorrect clearances?
Thats the bottom line.
Without the extra expense of going semi-exotic (which the stock assembly is) you will be lucky to find anything lighter and cheaper.
03-15-2018, 02:29 PM
#13
Team Owner
About as good as any deal I've seen out there for a basic rebuild...https://www.ebay.com/itm/GM-LS7-ROTA...4383.l4275.c10
Re-conditioned GM LS7 Forged Steel crankshaft (P/N 12641692).
Re-conditioned GM LS7 Forged Titanium connecting rods (P/N 12586258).
New Malhe LS7 Pistons (P/N LS7181130F03).
New Clevite Main Bearings (P/N MS2199PN).
New Clevite Rod Bearings (P/N CB663PN).
Thought of you Bee Jay when I saw this a while back because of the .005 over, but I know you have one liner potentially getting in the way of only going .005 over.
Re-conditioned GM LS7 Forged Steel crankshaft (P/N 12641692).
Re-conditioned GM LS7 Forged Titanium connecting rods (P/N 12586258).
New Malhe LS7 Pistons (P/N LS7181130F03).
New Clevite Main Bearings (P/N MS2199PN).
New Clevite Rod Bearings (P/N CB663PN).
Thought of you Bee Jay when I saw this a while back because of the .005 over, but I know you have one liner potentially getting in the way of only going .005 over.
Last edited by MTPZ06; 03-15-2018 at 02:30 PM.
03-19-2018, 03:22 PM
#14
Le Mans Master
About as good as any deal I've seen out there for a basic rebuild...https://www.ebay.com/itm/GM-LS7-ROTA...4383.l4275.c10
Re-conditioned GM LS7 Forged Steel crankshaft (P/N 12641692).
Re-conditioned GM LS7 Forged Titanium connecting rods (P/N 12586258).
New Malhe LS7 Pistons (P/N LS7181130F03).
New Clevite Main Bearings (P/N MS2199PN).
New Clevite Rod Bearings (P/N CB663PN).
Thought of you Bee Jay when I saw this a while back because of the .005 over, but I know you have one liner potentially getting in the way of only going .005 over.
Re-conditioned GM LS7 Forged Steel crankshaft (P/N 12641692).
Re-conditioned GM LS7 Forged Titanium connecting rods (P/N 12586258).
New Malhe LS7 Pistons (P/N LS7181130F03).
New Clevite Main Bearings (P/N MS2199PN).
New Clevite Rod Bearings (P/N CB663PN).
Thought of you Bee Jay when I saw this a while back because of the .005 over, but I know you have one liner potentially getting in the way of only going .005 over.
03-29-2022, 01:13 AM
#15
Racer
Bumping this old thread to the top to see if anyone's aware of any newer, lighter parts that have been made. I need to rebuild my motor since 4 of my titanium rods are bad but I'm not sure about re-coating them or even using titanium rods at all due to the coating wearing off - but it also sucks to lose HP via the increased weight of heavier forged steel rods.
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SeanDon210 (03-29-2022)
03-29-2022, 11:32 PM
#16
I definitely noticed the LS7 rotating assembly is hugely heavy compared to my LS1. Throttle blips are quite a bit slower in comparison. I figure it's simply due to the 4"x4" stroker configuration combined with a heavy balancer, flywheel and clutch. The LS7 has very big pistons with a large stroke. Titanium is a bouncy material vs. stronger unforgivable steel. Apologies if this information doesn't help choose a lighter rotational assembly.
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SivaSuryaKshatriya (03-30-2022)
03-30-2022, 06:45 PM
#17
Melting Slicks
I doubt you will find an inexpensive lightweight rotating assembly other than the OEM LS7. If you want quality the price goes up. Check with CNC Motorsports on a Callies rotating assembly. You can go cheap and use Eagle parts but the end result may cost you another rebuild.
A poorly understood issue is rotating weight. A lighter weight assembly does not necessarily produce more power but may accelerate faster until to connect it to a 3000# car.
Best of luck!
A poorly understood issue is rotating weight. A lighter weight assembly does not necessarily produce more power but may accelerate faster until to connect it to a 3000# car.
Best of luck!
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SivaSuryaKshatriya (03-30-2022)
03-31-2022, 07:33 AM
#18
Le Mans Master
As far as rods, you can't get much lighter than a LS7 titanium rod. I've found a few steel rods that are 550-580grams a piece. AFIAK, the LS7 crank is pretty heavy. There are a few options out there that are a little lighter, which could make up for the slightly heavier steel rod. Then any off the shelf piston with your desired compression height will work.
04-02-2022, 08:00 AM
#20
A heavier rotating assembly will not cost any power vs a lighter rotating assembly. Throttle response, yes, marginally. Acceleration, yes, marginally. I have a forged Callies Compstar crank, forged Compstar rods in my LS7. Yes, Callies offers slightly lighter cranks, like the DragonSlayer. But it would take a mighty good ear to hear the difference between my engine, and a Ti rod setup when it comes to throttle response. Probably most noticeable when letting off the throttle, and losing rpm, than under throttle gaining revs. With 127-130mph 1/4 mile trap speeds, nobody will know the difference!! Road racing would probably favor the Ti setup. Problem is, if you already have a new stock crank, I've heard that the OEM LS7 cranks can't be easily balanced with the heavy rods and forged pistons. So you may be forced to run Ti, or aluminum rods. I've never gone that route, so can't go by my own experiences, only what I've read, and heard. Best of luck to you.......