Utinator

Would the longer snout of the LS7 crank cause any issues with a normal Gen-3 or Gen-4 wet sump set up? I have found some used LS7 cranks for far cheaper than any after market 4" stroke crankshafts. I just wasn't sure if it would cause any issues with the stock (LS1, LS2, LS3) front pulley and accessories. The 58x reluctor can usually be swapped to 24x if necessary, so I'm not real concerned about that. From what I can tell, all the main and rod journals are the same. Are there any other issues with using an LS7 crank in a non-LS7 block?

Che70velle

iTrader: (6)

You can easily have the snout cut down to the correct length, so that’s the easy part. The problem with using the LS7 crank in a non-LS7 application is the bobweight. Balancing the LS7 crank is crazy expensive because of all the tungsten that has to be added, to get it to balance. So between adding the tungsten and cutting the snout, your within a tank of gas of getting a Compstar, or K1, and prolly about the same coinage as the Summit Pro cranks. Just not worth it…

jayyyw

I agree on the cost of balancing. Cost is around $800 to balance the LS7 crank with heavier rods and pistons.

Che70velle

iTrader: (6)

I asked a guy once if Tungsten had gold in it…

Utinator

I’ve never seen anyone add weight to a crankshaft. The weight is normally removed from the counter weights. Doing that is only about $375 locally.

I would be using a smaller bore, so the pistons should be lighter. The rods might be heavier though.

Che70velle

iTrader: (6)

Goodness. I’ve added weight to many a crankshaft. The LS7 crank discussion has come up here quite a few times in the past. Many before you found that adding the weight simply was cost prohibitive. I’d go K1 or Summit crank if I were you, and have it spec’ed for your assembly, to keep balancing costs at a minimum, as you posted is usually $300-$400.

jayyyw

The LS7 rods are mid 400 grams. Even if the pistons are lighter than the stock LS7 pistons, you'd likely still be over the stock weights and thus need to add material to the crank. Which will increase the cost.

Utinator

I would definitely ask my local machine shop about this before buying an LS7 crank. Maybe they have dealt with this situation before. I can understand how changing the bob weight dramatically would cause balancing issues. I didn't think it would be that big of a difference. Titanium is lighter than steel though.

Che70velle

iTrader: (6)

The Ti rods are much lighter than steel…like over 100 grams lighter than a comparable length H-Beam rod. That’s the difference mostly. Around 800-1000 grams total with 8 rods. It’s definitely not worth the hassle.

grinder11

iTrader: (1)

Che70velle is spot on. When I put my wet sump LS7 together, everyone told me to just go aftermarket, Callies, whatever. Said balancing would be an expensive, and sometimes almost impossible, task.

jayyyw

I was over at my engine builder's this weekend. We were talking about the balancing process. He charges a flat fee for a standard balance, that involves only removing weight from the crank. Then he showed me a small, 71g piece of Mallory that cost roughly $50. It was about 1/2" diameter by 1" in length. I've seen cranks that have larger pieces added to them for balancing. So the cost of Mallory, plus the cost of the labor to install it on the crank, on top of the flat fee he charges. I know one he did recently was $800. That was aftermarket rods and pistons on a stock LS7 crank.

QwkTrip

iTrader: (23)

All the LS2/LS3 wet sump parts will fit but you'll need to use the longer LS7 damper bolt with a damper hub spacer so the bolt head has something to clamp against.

​​​​​​​Crank scraper and windage tray gets to be a little more tricky.

Utinator

Well, I would prefer to use either a 4.1" or 4.125" crank anyway. I have just seen some LS7 cranks for pretty cheap. I guess it's not really worth it to adapt it to a non-LS7 engine.