Making a 400 stock SBC live.

[pdq67]

I have posted before about installing a top 1/4" plate across the banks as well as making a main girdle that would tie into the top plate using long bolts to tie them together. Then install sleeves.

BUT just what will make a 400 SBC block live if I boost it to like 75 psi!!

pdqw67

[SupStk]

Might work. How thick is your wallet? How good is your prayer life?

Assuming you are talking about a stock GM block? Is there a reason you don't want to use a block that realistically might stand a chance at living?

[jred]

unless your time and machine work is free you can buy a dart little m block for only a little more then what it will cost in time and effort to try and band aid a stock block to try and make it work,,, think about it you spend money for a half decent crank and rods and try to fix a stock block for that kind of boost.. the block is your foundation...

[user-17438]

I have posted before about installing a top 1/4" plate across the banks as well as making a main girdle that would tie into the top plate using long bolts to tie them together. Then install sleeves.

BUT just what will make a 400 SBC block live if I boost it to like 75 psi!!

pdqw67

All it would take is a cylinder head with .25 inch intake valves and similar cross section area.

But in reality, don't waste your time or money.

Sure you could make a new deck, put 8 sleeves in it, but then you still have the crappy lower end and block material. No girdle is going to fix the detonation from 250 + degree air temps

[Frankshaft]

Its not the mains. Its the cylinders. They are thin, and really close to the bolt holes. They crack, and migrate into the cylinder, and the cylinder splits, hydro lock, and boom. That's the problem with 400 blocks.

[englertracing]

Pdq

I dont understand your fascination with the lowly mostly stock sbc engine.

A cg aftermarket block is what you would actually want
Just spend the money on that part, you can have some ring seal with the 4.125 bore, raised cam, larger cam journals (whats funny is that the "big" 55mm journals are about the same as a stock sbf, and the raised cam puts it around ford height) that stuff lets you run a real camshaft.

Maybe an ls iorn block can do it.....
Then theres the advantage of ditching the assinine nonsensical pinch port BS making it look like a ........ Sbf......



Heres a real stock block/crank/cylinder head casting monster.
https://youtu.be/DnCsQPpY6xA
2300+hp

[englertracing]

Also just what is girdle gonna do?
Nothing?
Yes thats exactly what it will do....
What would do something is a bedplate.
And that would be a TON of work and probably cost more than an aftermarket block to make.

[governor]

I have seen 3 400 OE block break in the cam tunnel area, Not sure the effort is worth the investment in time and resources.

Gov

[mag2555]

Why don't you just run straight Nitro and kill the motor in one dyno run or pass instead of 2 or 3 with 75 psi ( if the head gaskets even hold passed 60 psi) of boost, in this way you will have more time to build the motor with the parts it should have been built with in the first place, lol!

[houser45]

Stupid. Buy an aftermarket block

[travis]

75 psi??!!

That sounds like a really expensive proposition to me. I bet the explosion would be pretty spectacular though!

[tt 383]

Just get a good block, figure a very mild 400 should make 400hp, at 14.7psi you will be close to 800hp and 29 is going to be close to 1200hp...

[Newold1]

I am never quite sure "where" pdq67's thoughts , ideas or questions come from?? I will not spend my time answering his crazy thoughts! I think he is just pushing buttons! I'm gone!

[lefty o]

is this going to be 75psi at 9000rpm?

[Tom Walker]

I have always thought it was a well known fact that a 400 production block will fail at 73 P.S.I.