engine blocks and cranks

[TurboCruisin]

Do 86-87 GN crankshafts have a casting # if so what is it and what is the difference between it and any other 3.8 crank? would a 109 block from a N/A engine have a turbo engine type crankshaft

 

[KendallF]

Go see the block and crank guide at www.gnttype.org. The turbo cranks have a rolled fillet on both rods and mains, which differs from the stock NA crank. Probably the only time you'll find a NA motor with a turbo crank is if it was a late GM Goodwrench service replacement motor; some of them got turbo cranks. The block, rods, and heads are all the same whether NA or turbo, though.

 

[hgriz]

So then what is the difference between the NA block and turbo block besides the hole drilled for the turbo oil return? What about the heads?

 

[FJM568]

um...

nothing...

and um...

nothing...


I think Kendall already said that, tho...

 

[TurboCruisin]

drain hole

Jim, do you know anthing about making the drain hole for the turbo. It doesnt sound like a big deal to make one in the front of the block.

 

[FJM568]

Just drill and tap a new hole in the cast-in boss that is there already...

Just have the machine shop that does your engine machining match up the threads on your turbo oil drain tube and drill and tap the new hole in the block...

 

[Trois Buicks]

...and the hole should be 1/2" NPT, last I heard. We have a local guy here who drills n/a 6109 blocks for turbo use on a regular basis.

 

[dfisher]

I ran a drain to the pan real simple,pan came off no problem.Just another idea if you dont want to drill the hole.

 

[equalizer442]

so a 83 t type block and crank are just as strong as a lc2s?

 

[FJM568]

The block can be used, but the later 109 blocks are the strongest production blocks to use...

As for the crank...It is the same crank...Although it may use a smaller balancer bolt on the front...But that can be drilled and tapped out to the bigger one by a competant machine shop...I do know that the earlier cranks used the smaller bolt, but not sure about the 83's...