. . . years ago you could do whatever and drop it in a car but with todays high tech computer cars is tuning a issue? Thanks
You'd have to get a tune for the new configuration, if that's what you mean. Whether a close enough mail-order tune exists or if you'd have to go through the dyno tune process (which is really the way to go regardless) is a separate question. But this is really just the electronic equivalent of having to sort out the carb and ignition that you'd have done for a stroked engine back in the day.
Adding stroke does not add valve curtain area that you couldn't add in a stock-stroke motor with the same bore. Ultimately, this starts affecting the stroker motor at a slightly lower rpm.
There is another rough guideline having to do with holding mean piston speed to some more or less fixed number, which you'll hit at a lower rpm with a longer stroke.
And there is side loading on the piston skirt, which is tied to rod length as well as to stroke. Keep in mind that if you're eating up more of the block deck height with crank throw offset, there's less left for longer rods to hold the rod : stroke ratio anywhere near constant. It's unlikely that with any significant increase in stroke that you can cheat enough length out of the piston pin location to do that. This is probably a durability issue more than it is related to the amount of power you can get out of the combination, but it is still something to think about.
I'm well aware of the SBC interchange possibilities. If I really "needed" a 380-ish CID SBC I'd build an 0.030" over 400-bore block/350 crank combo for 377 CID before going the 0.030" over 350 block/400 crank route for 383.
My reference points for not much appreciating long stroke motors isn't "John Deere", but the 5000 - 5500 rpm limits on virtually all of the long-stroke British sports car engines of the 1960's and the 400+ CID B-O-P engines of the mid/late 1960's. The Brit engines were done up long-stroke because of Britain's peculiar tax structure that penalized bore size as a means of determining "taxable HP", and I'm guessing that low end & midrange torque was more important to GM in those other applications. Yeah, I know what Honda and Audi have managed to do with their undersquare engines, but I can't help thinking that they could have been better still at the same displacement with something like 1/8" bigger bore and a quarter inch shorter stroke.
Norm
