Big cubes in a small six block

[AzCoupe]

FSPP is working with a shop in the LA area, which is building up a couple motors for us. One will be tested in Kelly's Falcon with the trubo setup and the new aluminum head, the other in my 66 coupe with a Magnuson blower and MPI. Hogan's Racing Manifolds is designing & fabricating aluminum intakes, Clay Smith is working on the roller cams, and we will use the new DUI dizzy's.

The shop came up with an idea that is very interesting. They are going to bore out the cylinders and wet sleeve the block with a 4" bore. They plan to use custom rods and pistons to achieve a 4.25 stroke. If it works, it will yield 320 cubes from a 250 block. They aren't sure about the 4" bore, but are pretty sure it will work. If not they will downsize to 3.875, which still puts up an impressive 300 cubes. The only thing I can see that might be an issue is cam clearance??

They already ordered the parts, so its not just an idea sitting on the drawing board. The goal is to have one ready for the first PSCA race in mid March, however we will be using a cast OZ head until an aluminum prototype is ready.

Attempting this with a 40 year old American inline six design may create one expensive grenade. However if we are successful .....................................

Of course, FSPP will offer crate motors if the design is reliable for street use.

 

[wallaka]

Wow...it's great to see you and others constantly push the envelope on what our sixes can do. I can't wait to see what's next...and hopefully contribute to the cause.

 

[Asa]

HOLY CRAP!
320 cubes?!?!?!

i'm speechless, honestly

cripes Mike, we gotta get you hooked onto a big six, let you get that fever in your blood

 

[SuperMag]

Attempting this with a 40 year old American inline six design may create one expensive grenade...

Yeah... if you wet-sleeve the block, you lose the structural rigidity of the cylinders. I could see it working as a modestly rated daily driver type engine, but as a high HP, highly stressed race motor... (Can I watch?)

Seriously though-- I hope it works.

 

[70stangcoupe]

this is a little off subject, but you mensioned an aluminum head. Is there any estimate as to when its going to be available

 

[82F100]

Evan, as for the big 6 I'm workin on him to start working on some stuff 70stangcoupe, on the aluminum head see AZCoupes other posts.

 

[Does10s]

DEAR GOD!!!!

I guess I'd better get started on a roll cage!

Will

 

[80broncoman]

AZ, I'd measure the clearence now and do some calculations. with this being a prototype cams and all, Just don't heat treat the cam core till you know it will fit. You might need a smaller base circle on the cam.

 

[Does10s]

Rich,
At 320 cubes......that is the "big 6"!

Will

 

[Anonymous]

Mike,

Cool idea, but wont the rod bolts hit the cam? The cam is notched for clearance but they still come pretty close

I thought I had a pic some where of how close they actually come but I cant find it...

Later,

Doug

 

[wsa111]

Good luck on your project.

When you get a small block chevy at the 415" & beyond, the rods have to be chamfered, smaller base circles for the camshafts & many more mods such as notched oil pan rails dimpled oil pans at the oil pan mating surface & notched cylinder bores at the bottom.

Where there is a will there is a way.

Keep up the great work Mike. Even a little more stroke would help. William

 

[addo]

Doug, the 250 cam is further away by two links (about two inches total, so maybe an inch extra clearance). Still, it'll be close. The Oz speedway guys will be watching.

Can anyone else "hear" this motor on the overrun, with Webers or triple SUs and a long duration cam?

 

[82F100]

Will, I might have to take the pinto back to the chassis shop to be fitted for a small six Isn't it a couple of inches shorter than the 300?Talk about engine setback

 

[AzCoupe]

If it gets off the stand, we plan to bolt it up to a dyno for the break in, and do a video.
I'll post it for all to enjoy, that is unless I'm to.....

Hey, its worth a try Right? Even if it does grenade, it will be fun to watch.
"Inline Explosion" coming this spring on DVD.

But if it works............ that nine inch rear in Kelly's Falcon may not be overkill afterall.

 

[Anonymous]

In the past my father has bored a 250 to to suit a wet sleeved 4" bore, and ran into the oil galleries.

 

[peugeot bill]

we have overbored these blocks and sleeved them, but to make them work you have to blok fill, there is an epoxy that you fill the block with to gain strength. you fill to within 1" of the top of the block and it's like concrete. you only need to cool the head and top of the block for drag racing. and if you run the engine on alcohol, shoot all you need is an expansion tank. lose the weight of the radiator, water pump, drive!
and it's good for the environment! wink wink!

 

[rbohm]

8) mike, you might have your engine builder do what bob glidden did in the 70's with his pro stock 351c's. he had the cylinders bored out enough to fit a sleeve that was .250" thick, and had the sleeve furnace welded in place so he could bore the cylinder .080" over. this not only allowed him to build a large bore small block, but it strengthen the block considerably. might give it a thought. cost is going to be the big thing though.

 

[ASMART]

How far can you go on a 200 bore wise with a dry sleeve?

 

[Crosley]

no subsitute for cubic inches. it should be intersting!

 

[69Falcon]

How far can you go on a 200 bore wise with a dry sleeve?

That's a great question! I'm very interested in the new heads coming out, but would like to freshen up the bottom end while I'm at it. (In for a penny, in for a pound.) Besides adding a blower or turbo, how many cubes can you get out of a 200 without radical machine work?