my current setup is 406ci on a factory block, it is splayed and im using headstuds. i am using twin precision 6176s at 16 psi on a blow through e85 950hp built by hp innovations. the setup is expected to make 1000hp at the crank. i have not drove the car yet as im finishing up some odds and ends. the motor is in a 3700lb 72 chevelle and will not see past 6200 to 6400rpms.

im worried that the block will go right away. as soon as the engine is together i wwill start building a little m based 415. will this motor last me year or 2? i will put roughly 500-800 street miles and probably 5 or so outings to the strip

 

that's ALOT of power for stock 400 block. I don't think it will make it for a year or two.

 

Turn it down, leave it down is my opinion. You're going to spit something out if you don't.

 

What is the casting number of the block? Is the engine equipped with a high quality crankshaft?

 

Ill have to look at that casting number. Its a forged eagle crank, forged h beams, forged dss pistons and total seal rings. Its all high quality parts with the exception of the block.

 

it really depends on the casting number and the core shift in that block. even a good 509 block with splayed caps and a 1/2 fill with hard block is good to 700hp or so anything more and its days are numbered. make sure you keep it cool and dont let it detonate and you will have a good engine to get the combo dialed in. while building another engine. or just pickup a dart shp block and use your lower end.

if not I thing a late vortec 350 4 bolt block with good rods and pistons to make a 383 is about as strong as you can get with production parts.

 

the 400 blocks are

509 best
511 good and
817 castings in that order.
I have found the late 70s blocks to be better with less casting core shift than the early 4 bolt 817 blocks. I have ran a bunch of 406 engines over the years and I feel a good 509 2 bolt block with studed 2 bolt caps is just about as strong as they get. without block filler the bores tend to crack before the mains start to walk around. im sure the good caps help good luck.

 

i think i will turn it down to 8lbs, it is an 817 casting

 

and are the motown race blocks any good?

 

Another boosted 72, I'm liking this!
Can you post some pics of the car and setup?
Good luck with it, sounds pretty wicked!

 

Sure can, im using wrenchrat hotside and everything else i fabbed myself, dad gave me the car as he lost interest and its been sitting in the corner as a roller for the past 5 years. It gets paint this spring also.

And it turns out the small springs in the wastegates are 5.8psi so thats what ill run for now

 

If you're going to spend money on an aftermarket block then you're much better off purchasing a Dart product. Even an SHP block is a better choice than the MoTown block.

For what it's worth I have seen some 817 castings that have extremely thick cylinder walls, sometimes as much as .230" - .280" on the thrust side. There isn't any consistency that I've ever seen as to what model vehicle or production year that GM used these thicker-wall blocks, but they do exist. The only way to know for sure if you have a thick-wall 817 block is to have the cylinders sonic tested for thickness.

 

Are you sure theyre no good? A guy i work with has a merlin 3 block and makes 2006hp at the crank. He said hes running 33.8psi on a 1471

 

Why are you comparing bbc to sbc????

Engine builder I know did the old measure the bore with and w/o the torque plates after a hone on several bbc blocks - of the aftermarket blocks, World block moved the most, Dart didn't move at all.
This was a Merlin or Merlin II.

Stock bbc are good to 1200+ all day. Dart are in the 2500hp range.

So-

Why are you comparing bbc to sbc????

 

You're taking a risk with a World casting. Some are ok, some aren't so great. If you get a chance to see a Dart and a World block side by side you will be shocked at the difference in casting quality and machining quality.

 

I was comparing bbc to sbc because its the same companys castings.

And dart it is then

 

sorry it took a while but here is the pics. it still has a ways to go

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That hot side looks amazing every time I see it. They did a ton of work in the layout. Good luck with her and the Dart block. I bet you'll need it sooner than later.

 

My only complaint is the wastegate recirc tubes wouldnt allow me to bolt on the valve covers.. so i welded them shut and im just using the recirc tubes as dumps

 

Very nice! Looks great.

Where did you source that alternator mount?