Questions about hot air block and 109 block

[Sweetblack85]

Hello I'm thinking about rebuilding my hot air block. Is it a difference in these blocks other than nickle content and oil galley? Can I buy parts like Pistons, cam bearings for 86-87 gn? Are the cranks and rods the same for both factory blocks? I know the oil pan and timing cover gaskets are different too. Any info would be greatly appreciated.

 

[Nick Micale]

Over 20 years ago it was proven the the material and nickel content in Buick V-6 and V-8 blocks was the same as all the other GN blocks of that era.

As far as block strength, the weak point in the 109 block is the same as earlier V-6 blocks, and it is the thin web between the main bearing saddle and the cam bore. We have seen many 109 blocks trashed there.

Unless you are building a 600+ HP engine, you should be fine with either block.

Cam bearings are different, but crank, rods and pistons will all work in either block.

 

[Sweetblack85]

I'm doing about 450-500hp will the factory rods and crank be ok to reuse for this hp level?

 

[d0n_3d]

Factory internals are good for like 600 flywheel hp as long as you do not have detonation. Plenty of people have gone insanely fast on factory crank and rods.

 

[usetaboost]

Over 20 years ago it was proven the the material and nickel content in Buick V-6 and V-8 blocks was the same as all the other GN blocks of that era.

As far as block strength, the weak point in the 109 block is the same as earlier V-6 blocks, and it is the thin web between the main bearing saddle and the cam bore. We have seen many 109 blocks trashed there.

Been saying the same thing for years. Had a few tell me I was dumb for building a block that wasn't a 109 Then turn around a build a 4.1

 

[usetaboost]

Just keep sending all those worthless 78-85 engines my way

 

[Nick Micale]

Factory internals are good for like 600 flywheel hp as long as you do not have detonation. Plenty of people have gone insanely fast on factory crank and rods.

My experience with a few hundred engine builds is the the stock, cast crank is a major weak link.

At the 500 HP level you will see lots of bearing wear due to crank flex. At this level and above, reliability of a 30 year-old cast crank is uncertain to say the least, as metal fatigue will take its toll on durability with a cast crank.

Another factor is how will the engine be treated? Lots of high RPM and high loads and stress with many full throttle shifts will subject the crank to extreme loads and stress.

With a 10 sec. build at the 500+ HP level, the smart thing to do is spend a few $$$ for a forged crank and eliminate the chance of taking out the engine and trans with a broken crank.

 

[Sweetblack85]

What's a good replacement crank? Will the factory cam be ok for my 450-500 hp level I have a 3000 stall torque converter. . .

 

[thadeal4real]

Oil pan might be the same just sayn

 

[turbofabricator]

I agree with Nick. (As usuall). You "can" use stock crank and rods at that power level, but why? A cheap Chinese 4340 crank is so much stronger.

 

[Sweetblack85]

Thx guys for all the knowledge I really appreciate it!