Spread bore blocks

[Ratu]

I have been reading about the manufacture of new cylinder blocks both by manufacturers and also by the after-market. For example, for NASCAR everyone is now building cylinder blocks with 4.5" bore centres although the small block Chevrolet was originally set at 4.4", Chrysler's LA at 4,46" and the Windsor/Cleveland Fords were 4.38" (Toyota has had V-8 engines for a long time but none of them are related, even distantly, to their NASCAR engine so they are a separate case for the purposes of this discussion).

More interestingly is what is going on for the big blocks though. Ford 385-series Lima had 4.9", Chevrolet Mk 4 was 4.84" and Chrysler B & RB were at 4.8". Of course there were Cadillacs and, before them, Packards at 5". I see that the aftermarket has been producing bores pitched at 5" centre for the Chevrolet big block. Also some have gone further yet at 5.3" and even 5.4", although that is the largest I've been able to find.

Two questions.

Are there Fords and Chrysler spread bore blocks available?

What is the largest bore pitch presently available?

[pdq67]

Ratu,

I think the old Ford Super Duty MEL 534" truck engine block is 5.25" bore spaced.

Not an automotive engine because it is so massive, but none the less, 5.25". I think that I have read where one weigh's like 1,100 to 1,200 pounds? And food for thought, Ford made a marine version that was turbocharged if not mistaken...

I have often thought about acid dipping one and putting the block and heads on a diet just for the fun of it to see what would happen.

Lighten the crank too.

pdq67

[DaveMcLain]

Ratu,

I think the old Ford Super Duty MEL 534" truck engine block is 5.25" bore spaced.

Not an automotive engine because it is so massive, but none the less, 5.25". I think that I have read where one weigh's like 1,100 to 1,200 pounds? And food for thought, Ford made a marine version that was turbocharged if not mistaken...

I have often thought about acid dipping one and putting the block and heads on a diet just for the fun of it to see what would happen.

Lighten the crank too.

pdq67

The Ford Super Duty and MEL engines are different engines and not in the same engine family. You can buy Ford big blocks with a 5 inch bore spacing from people like Carrol Carter etc which can be used to build very large displacements, over 800 cid.

[peejay]

Where do you draw the line?

I remember working on an Isuzu diesel six that must have had a 6" bore spread. Close to seven liter engine with only six cylinders. Rod bearings looked bigger than most engines' mains.

[Roundybout]

Reminds me of the thread with the huge two stroke diesel ship engines. They had bore centers measuring in feet. In an unlimited displacement engine you can only jam so much stroke in a block so bigger bores are needed. Limited displacement a bigger bore with a comparatively smaller stroke can offer better breathing ability and more manageable piston speeds. Piston speeds have to be pretty ridiculous on a longish stroke/standard bore center block that is maxed out on the bore size and the only way for more HP is RPM.

Manufacturers designed the engines on whatever criteria at the time was important and bore centers decided on. Once that tooling was made they weren't changing it lol. We've now got to the point for large engines the OE style bore centers are the limit. There are people out there opening their wallets so the demand is there.

[Alaskaracer]

You can get aftermarket blocks with bore spacing up to 5.3" right now. Not sure you'll see anything more than that as those blocks allow for 1000"+ builds already...Be aware though, these will be billet and VERY EXPENSIVE.......the bore centers are just a matter of a small change in programming before the CNC starts up....

[peejay]

You can get aftermarket blocks with bore spacing up to 5.3" right now. Not sure you'll see anything more than that as those blocks allow for 1000"+ builds already...Be aware though, these will be billet and VERY EXPENSIVE.......the bore centers are just a matter of a small change in programming before the CNC starts up....

And the heads....

And the crankshaft and camshaft...

And the intake manifold, oil pan, and all the gaskets... Although for the expense already involved, i wonder if it would be actually easier to just mill grooves for O-rings instead of having head gaskets made.

[Alaskaracer]

You can get aftermarket blocks with bore spacing up to 5.3" right now. Not sure you'll see anything more than that as those blocks allow for 1000"+ builds already...Be aware though, these will be billet and VERY EXPENSIVE.......the bore centers are just a matter of a small change in programming before the CNC starts up....

And the heads....

And the crankshaft and camshaft...

And the intake manifold, oil pan, and all the gaskets... Although for the expense already involved, i wonder if it would be actually easier to just mill grooves for O-rings instead of having head gaskets made.

True, but all depends on what someone is looking for.....and how much they have to spend....

[Roundybout]

With enough money and someone with the resources huge engines are possible. I remember reading a hot rod article about a Sonny L. engine with a 5.220 bore/stroke 5.875 that made a claimed 2000+ at 8000rpm. That's some big pistons flying around.

[Alaskaracer]

With enough money and someone with the resources huge engines are possible. I remember reading a hot rod article about a Sonny L. engine with a 5.220 bore/stroke 5.875 that made a claimed 2000+ at 8000rpm. That's some big pistons flying around.

Sonny builds a 1005" engine that makes over 2100 hp....

[pdq67]

Ratu,

I think the old Ford Super Duty MEL 534" truck engine block is 5.25" bore spaced.

Not an automotive engine because it is so massive, but none the less, 5.25". I think that I have read where one weigh's like 1,100 to 1,200 pounds? And food for thought, Ford made a marine version that was turbocharged if not mistaken...

I have often thought about acid dipping one and putting the block and heads on a diet just for the fun of it to see what would happen.

Lighten the crank too.

pdq67

The Ford Super Duty and MEL engines are different engines and not in the same engine family. You can buy Ford big blocks with a 5 inch bore spacing from people like Carrol Carter etc which can be used to build very large displacements, over 800 cid.

If not mistaken, the Ford Super Duty big truck engines have MEL designed heads on them as well as non-90 degree angle cut decks!

But please check me on this?

pdq67

[Roundybout]

There is not much in common or interchangeable between Super Duty and MEL engines. Maybe some common bolt patterns, maybe some oiling components. Introduced the same year is about as close as they get. They are huge inneficent dinosaurs.