Bore & Stroke?

[427SnakeSC]

Thanks for the info Bob. I am trying to decide which bore and stroke to go with in my SO. Keith Craft is suggesting I go with a 4.25 bore and 4.25 stroke. What do you think of this combination? Thanks again.

[Bob In Ct]

482CID!

That's a lot of engine, big bore and long stroke. It's guys like you I never park next to.

Let me guess, you're going with the 4.11 rear and a no overdrive toploader.

Bob

[427SnakeSC]

Originally Posted by Bob In Ct

482CID!

That's a lot of engine, big bore and long stroke. It's guys like you I never park next to.

Let me guess, you're going with the 4.11 rear and a no overdrive toploader.

Bob

I have 4.11 in my Classic now. Pretty much useless 1st gear. I'm going with a CR toploader and a 3.54 final drive. Do you think the bore is too much? Should I go with a longer stroke?

[Bob In Ct]

Engine size in a Cobra is a very personal thing. If you need 500 CID with Webers then get it. If you're happier with a small block, a Holley 650 and mild gears then that's what you should get.

Everyone has a different view. Whatever you do, be sure it makes you happy. I would avoid the bowtie engine though.

Bob

[427SnakeSC]

Thanks Bob, I'll talk with Keith (Craft) and tell him what I am looking for and go with his suggestions. Everyone here on the forum swear by him. I was down to his shop last fall to talk to him about the 427 I want him to build for me. He seems like a pretty good guy and certainly knows his stuff! Okay, I give up. I gotta ask. What is a "bowtie" engine?

[scottj]

Originally Posted by 427SnakeSC

What is a "bowtie" engine?

The "bowtie" is symbolic for the venerable Chevy engine. Typically, the words "Chevy" and "Bowtie" should not be used on this forum. If reference must be made the term "chebbie" must be substituted to denote the proper disrespect. Surely you must know that any person that would put a "chebbie" in one of these kitcars is of the lowest moral character.

[427SnakeSC]

Here, here, I agree! Thanks for the info!

[blykins]

Coming to terms with yourself, Scott?



Sorry, had to say it.

[scottj]

Originally Posted by blykins

Coming to terms with yourself, Scott?



Sorry, had to say it.

Yes I have. I have also recently adopted the motto "If you can't beat 'em , join 'em"... just in case I lose someday.

[Anthony]

Originally Posted by Bob In Ct

The bore and stroke of a Windsor engine is 4X3.5 (which is the same as the 60s FE). It comes out to 352 cubic inches. I presume Ford chose to call it a 351 to avoid confusion with the old 352 FE engine.

yes.

Originally Posted by Bob In Ct

The bore and stroke of the 427 calculates out to 425 cubic inches. I've always wondered why Ford chose to call it a 427.

Actually, the bore is 4.233" and the stroke is 3.78" which comes out to 426. Mopar had just come out with the 426, so Ford called their new V-8 a "427" so as not to confuse it with mopar's 426, as at that time, engine sizes were marketed more, more of a PR thing. When Ford came out with their "428", with bore and stroke of 4.13" and 3.98", the displacement was actually 427", but they called that engine a 428 to distinguish it from the 427 they came out with several years earlier.

[cleandan]

Originally Posted by 427SnakeSC

It will soon be getting down to the wire on the Keith Craft build of my 427 SO. I would like to know which bore & stroke is the best to get and why. At his point I have talked with Keith and some of the specs on the motor are as follows. Stage 1 Edelbrock Heads, Blue Thunder Med Rise Intake, 750 Holley, fairly mild hydralic roller cam and 10 - 1 pistons. Cast Pond block. He has suggested the 482 bore. Thanks.

Unless the displacement is limited by some sanctioned race body you intend to compete in, I say do what you want. My suggestion would be to examine all available bore/stroke/rod/crank options and pick one that has a good rod ratio, a bore that is not to the max of the blocks ability for future boring needs, and that uses the most common parts. Good luck.

[427SnakeSC]

I have no intentions of racing the car. I was just wondering if there was some "magical" combination of bore & stroke that worked the best for these cars. I am looking for something to give me my power smoothly before 6000 rpm.

[Bob In Ct]

Keep in mind that an FE 427 runs different (less severe) connecting rod angles than does a 427 stroker. There is no free lunch. Engines designed from the get-go to be 427s (or whatever) will be less stressed than will Windsor engines which have been modified to have more CID.

Bob

[Excaliber]

Ford followed a 'golden rule' of basic engine design when they built the 427. Big bore, short stroke, like Porsche and many others have ALWAYS used. While in todays modern technology world it could be argued which is best, that basic rule (big bore, short stroke) still holds true.

Such an engine will fundamentally get to a given rpm quicker than a long stroke smaller bore design. So why are manufacturers now going to smaller bore and bigger stroke? It's easier to control EMISSIONS and generally speaking a lower rpm operating range (read that long stroke) makes better mpg. The fact that some modern engines perform excedingly well with a long stroke\small bore is a result of better head\cam\fuel control. NOT basic design! Same engine with a shorter stroke would do even better!

A 'square' design, same stroke and bore (283 Chebbie was such a motor), could also be argued to the best design, 327 was a longer stroke. The debate will never end... Look at all the great race engines around, the basic rule of big bore\short stroke STILL holds true.

I would NOT run a small block bored and stroked to excessive (in my opinion) numbers, like a 427 Windsor. Just TO stressed for me.

[DavidNJ]

My question is not why 482 and not 427. It is why 427 and not 496? Or 525?

The 4.31 bore is as well supported (rings) as the the 4.25. It seems like it would be the same cost. Why give up 14 cubes?

Now the 525 is 4.31x4.5. The only problem is there aren't any inexpensive 4.5 cranks.

JE lists 4.25, 4.28 and 4.31 pistons for the 4.25 stroke/6.7 rod combination. Diamond doesn't list the 4.31 in the catalog. However, as Barry said, they have it available.

[Streetwize]

The only thing overstressed about my 427 smallblock is MY NECK after driving it Proper machining is a must square decking, line honing, deck plate hone goes a long way on any motor.

BTW: A 283 chevy isn't anything close to square 3 7/8" bore 3" stroke, it would have to be 3.56" bore & stroke to be square.

A 327 is 4" by 3.25

The bigger bore than stroke was much more important years ago before modern cylinder head and combustion chamber designs evened the playing field. Rotaing mass (bobweight) has a lot more to do with how fast a motor will rev than bore and stroke alone. A 4.04" x 4.17" 427 smallblock with equal flowing heads, cam timing and compression will still rev quicker than an FE unless you have (for example) a knifedged lightened crank and aluminum rods to even up the mass. And not only the bottom end, valvetrian mass also has a considerable effect and again, advantage smallblock.

Most 4 cylinder 4 valve motors often/usually have much larger strokes than bores and some of them rev to 8500 or more easily. A mitsubishi 4g63 motor is a good example, early first gen (89-92) blocks have 1.6:1 rod ratio rods and routinely take 9000rpm and 24psi of boost and make over 350 streetable horsepower, to put that into perspective, a 427 would need to produce 1225 hp to equal that HP/Cube.

[Commander]

Originally Posted by Streetwize

Most 4 cylinder 4 valve motors often/usually have much larger strokes than bores and some of them rev to 8500 or more easily. A mitsubishi 4g63 motor is a good example, early first gen (89-92) blocks have 1.6:1 rod ratio rods and routinely take 9000rpm and 24psi of boost and make over 350 streetable horsepower, to put that into perspective, a 427 would need to produce 1225 hp to equal that HP/Cube.

Link

Your math is pretty close. I'm assuming the 24psi of boost was coming from a turbo? The FE above was dyno'd at 1,030. To drive the blower is probably over a 100HP, so call it 1,130 HP. And the owner was still working on the tune. I don't think he needed to go over 5,000 rpm to do those numbers either. I understand he's working on a twin-turbo FE hemi SOHC next.

9,000 rpm why? just to get 350 HP? a big block can make 350 HP right out of a clapped out 1967 LTD with a little freshening. You got to know what to spend your time on/with.

[Streetwize]

Originally Posted by Commander

Link

Your math is pretty close. I'm assuming the 24psi of boost was coming from a turbo? The FE above was dyno'd at 1,030. To drive the blower is probably over a 100HP, so call it 1,130 HP. And the owner was still working on the tune. I don't think he needed to go over 5,000 rpm to do those numbers either. I understand he's working on a twin-turbo FE hemi SOHC next.

9,000 rpm why? just to get 350 HP? a big block can make 350 HP right out of a clapped out 1967 LTD with a little freshening. You got to know what to spend your time on/with.

Well 350hp is at about 7400, it'll rev to 8800-9000. In addition to my Cobra I have one of these little pocket-rockets, and with the help of AWD and a 4800rpm rev limiter (for clutch dump launching on 6psi of boost) it's showed it's tail to quite an array of high dollar Fast cars. It's a total sleeper. There are many 1st get mitsus running upwards of 550hp on stock blocks and cranks, they were very well engineered little motors.

[DavidNJ]

The big problem with the Edelbrock's is the combustion chamber and the flow. It is basically a 1960's chamber with flow common for a 383 or so LS1. That is where the properly ported BT heads have an advantage.

The other is the carb, simple ignition curves, and no knock sensor. Net is your looking at a 482 or 496 with the power of a 347 or 366 LS engine with a hydraulic roller cam. Given that, I would go for all the cubes I could get.

Does KC recommend the Pond aluminum block over using the same money on better heads, crank triggered ignition, knock sensor, and maybe fuel injection?

[427SnakeSC]

The reason I was going with the Pond block is that I was told it is a very close copy of the original 427 SO block. I was also told that Genesis was having problems with their block, but have since been told that they have corrected it. Does anyone know which block looks more "correct?" "Correctness" is very important to me, with this car. I am not after hp at high rpm. I want my useable power to be in the 3000 - 6000 rpm range. He suggested I go with the Stage one heads, to get the hp at a lower rpm.