Turbo2L

I might be in the forged bottom end club over the next few months, so I began pulling weights together for two combos:

- Combo #1: stock crank, stock rods, and aftermarket pistons
- Combo #2: aftermarket crank, rods, and pistons

I'm still looking for aftermarket crank weights if anyone happens to have those I'll add them as well. I can't help but think +154g per rod won't go unnoticed and that a stock rod and Diamond piston would be 22g lighter per combo versus stock.

I'd also like to compile this same breakdown for valves, so keep an eye out for that edit. If you have different weights for what I have listed, send them to me along with the source and we will see what the vendor has to say. I kept my sources in my spreadsheet for the weights below. If anyone wants the aforementioned spreadsheet, shoot me a PM.

LS7 Rotating Assembly Data
Rods
Stock Rods - 464g
Stock Wrist Pin - 132g
Callies Compstar H Beam - CSC6125DS2A2AH 618g
Callies Compstar I Beam - CSC6125DS2A2AI 647g
Scat H Beams - 6612521A 635g
Eagle H Beams - CRS6125O3D2000 620g
Lunati H Beams - 665g

Pistons
Stock Pistons - 482g
Wiseco Pistons - K0004X125 6.067" rod 488g
Wiseco Pistons - K0004X130 6.067" rod 490g
Wiseco Pistons - K463X130 484g
Wiseco Pistons - K463X125 468g
Diamond Pistons 4.130" - D11581 (stock rod) 463g
Diamond Pistons 4.125" - D11580 (stock rod) 460g
Diamond Pistons 4.125" - D11585 465g
Diamond Pistons 4.130" - D11586 465g
Mahle 4.130" - LS7181130F03 (stock rod)
Mahle 4.125" - (stock rod)

Cranks
Stock Crank
Eagle Crankshaft
K1 Crankshaft
Callies Compstar Crankshaft

Valves
Coming soon...

gtodoug

great info!

Undy

Depending how much power you're looking for it's hard to beat the durability, lightness and value of the stock crank and rods with a good set of lightweight forged pistons. Don't forget to re-bush the small end of the factory rods if you reuse them.

Michael_D

I'd be curious to know what power levels / rpm your new build will see, or if there is another driver for wanting to move away from the OE rotating assembly.

I know you didn't ask for this, but for the general awareness of others who will eventually read this thread......

I have yet to see anyone provide definitive power/rpm thresholds for the OE rods and / or crank. I know of many builders who have these rods in engines making over 800 hp and running up to 8000 rpm (with bushings and bolts upgraded). The rods should, as Undy noted, have the bushings replaced. Katech is the best source for that. The rod bolts should also be replaced. Katech has a good set, and ARP does now as well. Might as well have Katech provide them while they are working the pin end. Katech did sell a forged piston for this engine, and it was pretty light, but I do not see it on their web site today.

The crank is hell for stout. It is forged with rolled fillets and bay to bay breathing windows, also lightened in all the right placed. Again, no real reason to swap it unless you are over 800 hp / 8000 rpm.

The pistons, while they are a cast piece, are quite good. They are not the A-typical cast slug normally found in production engines. These pistons were cast by Mahle, in Germany, and built to last at the piston speeds this engine sees with a 4" stroke and 7100 rpm. If you are going to boost or spray the thing, then they should probably be replaced to get lower ring land placement. If you are building this engine to power levels that would "require" a forged piston, you better be looking at re-sleeving the block as well.

Turbo2L

Great discussion points guys! PM coming your way Michael.

camONLYls1

Great post OP! Any luck finding crankshaft weights?

Turbo2L

Not yet - I've been sidetracked with projects at work. I hope to dive back into this in late March. Hopefully the lightest possibly assembly will result in longer life if I can translate the same concept to the top end.

The_Raging_Bull

Just a question from a fellow lurker, are thre folks who have used the ERL 4 or 6 bolt super deck 1 to build a numbers matching LS7 with the block in their car? The super deck with ductile steel inserts in an LS7 looks to be capable of building a 440 ci engine capable of being blown to 25 or 30 psi.

These are magazine articles on a 1437 HP build using this technology which is as over the top as just about anyone could go.

Just curious...

MikeOC

Mahle 427 4.125 6.067 rod 436 gram LS7181125F03
Mahle 429 4.130 6.067 rod 437 gram LS7181130F03
Mahle 427 4.125 6.125 rod 438 gram LS7105125F03
Mahle 429 4.130 6.125 rod 440 gram LS7105130F03

Turbo2L

Are those aluminum?

MikeOC

Yes, forged. It's the same part number you had in the OP but you didn't have the weights listed so I looked them up.

page 7
http://www.us.mahle.com/media/motors...compressed.pdf

Blackonblacksls

The stock crank loses its value once you add forged rods and Pistons because it takes a lot of heavy metal and a lot of labor to balance with a heavier rod and piston combo..

Blackonblacksls

And I say this because I have been there and done that, and spent as much on my stock crank as some of the forged cranks cost.

1Sikstik

phipp85

Good info here, subscribed.

Bad_AX

Actually the stock LS7 crankshaft isn't particularly light.

LS7 CrankShaft
2006 57.65lbs
2009 56.40lbs

For comparison.
Callies Magnum 4.0"stroke ~47.00lbs



http://ls1tech.com/forums/generation...ankshafts.html

Blackonblacksls

Overall weight isn't the issue, it's the bob weight that causes the problems when assembled with forged rods and Pistons.

MikeOC

I take it it is still necessary to rebalance the stock crank if I go from stock pistons to the Mahle, keeping the stock rods, but its it cheaper to rebalance a lighter combo labor wise?

Blackonblacksls

Yes the rods are what cause most of the problems.

Because the titanium ones are so much lighter than a forged or billet piece.

Vito.A

This thread is a great resource.
The lightest forged crankshafts are the Callies Magnum plus (all 4 rod throws through drilled). If you want the very best, then Sonny Bryant's billet cranks are the ultimate. Either one can be custom finished to your bob weight so not to require any additional balancing.


Will Katech install bronze bushings in OEM connecting rods? If not, is there another specialty shop that works on titanium rods?