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I have decided that me and a calculator is a very dangerous combination. I was figuring out what cubic inch I would get with a .125 over bore in my 327. after I found the info I was looking for I started playing around with the numbers and discovered that with a 4 inch bore and a stock stroke the engine would be 427 cubic inch(feel free to check my math I might have done it wrong). I found this pretty interesting as a piston blank would probably be easier to come by and it seems that the a 4 inch bore would actually fit in the block in reference to bore spacing, valves water, jackets, head studs ect. I realize that the cylinder walls are no where near thick enough for this and sleeves would have to be used possibly leaving not much block left by the time the work was done. I haven't decided if I am brave enough to make the attempt right now I'm thinking no. I figured I would share what I thought was some pretty interesting information.

Yes, the math works.

No, there's not a chance in hades it would work in the real world. FWIW, over the past fifty years, I've seen three professional attempts to do what you describe, a flathead Ford V8, a SBC and a Studebaker V8. None of the three could be sealed to hold coolant. Just too many inches of weld in cast iron.

Blocks which are designed to have pressed wet sleeves are made completely differently, with what might be termed an exo-skeleton. A solid cylinder block, such as the Packard, with the cylinders machined out doesn't have the internal reinforcement under the block deck and resultantly has the rigidity of a cardboard box.

jack vines

It is possible to artificially increase displacement by supercharging. To get a 327 to ingest as much air as a 427 would take about 5 pounds of boost which is quite doable.

Or you could get practically the same HP boost with conventional means such as cam, carburetors, header, valve work etc.

I think the supercharger would be better and cheaper. As long as you don't go too high with the boost no mods to the engine would be necessary. For certain technical reasons, your engine should respond well to a supercharger.

I agree totally on supercharging being a better choice than attempting to bore an engine out that far. It was something I found interesting so I decided to share.

I'm just curious on what the story was on the Stude and Ford you are talking about Jack. Even if the engines didn't work out they were probably a lot of fun when and if they ran.

The service limit from Packard was typically .045 on oversized pistons. I have seen .060 on pistons, and have been told .080 will crack, especially on the V-12.

The biggest problem with the L head is breathing. It will be like emphysema. The V-8 motor is more adaptable.

However if you want to turn cash into smoke don't forget nitrous injection in addition to the blower.

I'm not much of a hot rodder but nitrous and a blower should make for a big noise.

A blower will not only effectively increase the displacement but it will also somewhat overcome the poor breathing of a flathead engine. If you do it use a positive displacement blower like a Rootes. You get a lot of low end boost and there is no lag like you get with a turbo. 5 psi boost is easy, but I would shoot for something more like 7 psi to ovecome the power consumed by the blower drive. You may want to use high octane fuel if you use a blower. 7 psi is a half atmosphere boost so it will increase the power and torque by 40% or so without revving the engine any higher than stock.

Fred Puhn Quote:

Sorry Fred, "there is no lag like you get with a turbo" is an old wife's tale. It all depends on the engine size, cam and turbo size. I designed and sold a couple of hundred of the H-O TurboForce systems for 1970-79 Firebirds, primarily Trans Ams during the 1970s. "Turbo lag" was the least of our problem. Mostly the problem was traction due to excessive torque, even from a standing, closed throttle start. H-O also adapted the blow thru design to some 305 & 350 Chebbies at the time. Same result.

On an Packard S8, I think a turbo would be the way to go. Particularly an EFI blow thru setup like Eric (nee TurboPacMan) was planning.

Craig

The max overbore numbers you put out Tim are those in regards to the post war L8s or the early ones?

I've considered turbo and supercharger setups for my project and the only nitrous I would consider would be on a turbo setup to cool the inter cooler. Nitrous is pretty safe these days but if something goes wrong with your fail safes it will blow an engine very quickly.

A blower (or turbo) of some description at 7ish psi will give about 75 extra horses on a stock 150 hp 327 so 225 with no other changes from stock to there is potential to reach possibly 300 hp with an amazing rebuild cam and some intake magic which would be night and day from stock.

As Craig stated turbo lag is pretty much a myth these days I have known a few Thunderbird turbo coup owners that dealt with it in a stock setup but the tech these days is light years ahead of that now.

The problem I have had in a supercharger setup is packaging a Paxton style would be the easiest you can pretty much mount it anywhere you can get a belt to. I have a 471 sitting on the shelf that would be really good for a L8 engine but mounting it close to the exhaust would be problematic with all the heat in one area and it would look somewhat awkward but if you had a 300hp L8 Packard that would probably be the least of your problems.

In the real world as much as crossing my fingers and putting 4 inch bore sleeves in the engine would be very cool (till the engine blew) I am considering a .125 overbore if the block will take it which would give around 350 cubic inches. Then play around with possibly some big block Chevy rods and fancy pistons to get it all to work.

I wonder how different the block casting is on the '54 359 motor? Is it the same basic block core, and just bored out further than the 327s? Or is the block core actually different?