Destroking???

DarkShadowFord

DarkShadowFord

Forum Member
I know nothing of this subject but one of my friends mentioned

"that destroking a motor makes all the components lighter (due to it being smaller) increases the R.P.M. and giving it better acceleration."

Im am not sure about this but he wants to know what more experienced people know on the subject. Personally I would think that is a no go, just because the thought that stroking gives horsepower like a + sign, i would think destroking would lose power like a - sign, haha pretty stupid. But on the otherhand, I guess if you decreased stroke it could rev faster because the stroke isn't as long, less rotational mass? Please education me and my friend on this matter, the motor will probably be going in some old school muscle that he is building, so would that be a smart choice by destroking the motor, from the sounds of what he says he really wants to be quick off the line. My though process is, there is no replacement for displacement. Let me know your .02$...
 
It depends on what the reason is behind it. If you are class racing and limited to a certain cubic inch and not really limited on cylinder heads (i.e. canted valve heads are allowed), destroking would be a decent option.

For example if you were limited to 311 cubic inches, a 2.90" stroke with a 4.125" bore would put you just over 310 cui. Now throw a set up Blue thunder heads, or a yates head on it, and 10,000+ RPM can be had. It will have a ton of compression without closing the chamber off and destroying flame travel. It will rev like a mofo, so recovering between gears will quick as well. Torque is going to on the low side and don't expect it to make shit under 5500 - 6000 RPM. The key is not to take too much stroke out of it.

Now this is not to say that a 4.250" Stroke with a 4.155" bore small block can't rev like SOB and make a ton more power. It will but it will, but with much less RPM, given the same heads, similar intake, etc. An 8500-9000 RPM big small block doesn't sound too bad either.

In either case the high RPM is going to kill parts. Plan on replacing valve springs every 4-5 passes, and tearing it down frequently to inspect bearings or other potential failures.

IMHO, building a destroked engine for anything other than a specific class with a cubic inch restriction is a waste. Not saying a high winding engine doesn't sound awesome, but they are just very hard on parts. This brings budget into it....If you have one, don't bother. If money is no object, then go F1 racing.
 
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