Destroked LS2

[RobM]

i agree with what your saying, i was just bringing some other factors into the mix. this conversation could become endless but thats ok. I mean if you throw rod length into the mix it opens up even more doors of conversation

[68ls1wannabe]

Why the high rpms. V8's are about torque. Longer stroke = more torque. That is what move's the car right. Where can you use 8000 rpm on the street. That high winding motor would get it's ass handed to it by a properly setup turbo motor in a useful powerband. Say 2000 to 6500. I thought the whole idea of the turbo was to pack maximum amouts of air into the cylinders without having to turn the piss out of the motor. Check out ls1tech.com. They argue these ideas constantly.

[Kenova]

I normally try to stay out of discussions like this one, but sometimes I just can't help myself . I haven't had much experience building engines, and I've never seen the inside of a dyno cell, but I have done a pile of reading over the last forty years. What follows is merely what I think I have learned.
First off, torque is primarily a product of displacement. I've seen more than a few tests over the years where different bore and stroke combinations of the same displacement were tested. The torque and horsepower readings are usually within one or two percent, sometimes even closer.
A shorter stroke with longer rods reduces strain on the rod bearings, rod bolts, rods, and wrist pin. The friction from thrust side loading is also reduced. Does this result in more power? Usually not, but if it makes life easier for your engine, why not do it?
Just because an engine has a short stroke and big bore doesn't mean you have to wind it up to the moon. Lord knows there are more than a few Ford 5.0s (3.00s x 4.00b) lugging a variety of trucks and land barges around. How far you wind an engine up depends on how big of a cam you have (and the size of your gonads).
With the advent of modern fuel injection and turbocharging, large displacement engines are not always necessary. Although it will always be easier to get the same torque and horsepower out of a larger engine.
Now for my personal preference. If I were building a turbo engine for street duty, I would use a 4.125" bore so the heads can breath more freely. The crank would be in the neighborhood of 3.25" with 6.125" rods for a displacement of approximately 350 cu.in. With a good turbo system it would make plenty of power for the street and I would have a slightly higher comfort level due to the short stroke and long rods.
Needless to say, all this goes out the window if you must conform to racing class rules.
Ken

[nancejd]

Don't forget that their is a difference between engine torque at the flywheel and torque at the wheels due to gear multiplication. The chief disadvantage I can see with the smaller displacement higher winding motor is that you'd need more gear in the differential to overcome the torque disadvantage, which would result in a higher rotational speed for the driveshat. You'd potentially be a lot closer to the driveshafts critical speed. On the plus side, how much torque do you really want to make a t a low rpm anyway? Can you really hook up a big block on the street? Or most turbo small blocks for that matter? I think something that came out of the hole soft and just kept going could be interesting on the street.

[68ls1wannabe]

I believe one of the best motors to build is the 6.0 LQ4. It's an iron block so no issues with strength. Stpck bore at 4.00. Get a forged eagle rotating assembley, 4.00 crank, rods, pistons. Keep compression at 9:1 for turbo or 11.5:1 NA. Port the stock heads and use comp 921 springs. Lightweight valves "like the LS6". New cam. LS6 intake or if budget permits the FAST 90/90. More power than u know what to do with and getting the job done under 6500 rpm. Say goodbye to those new rear tires.