Destroking the KA??

[Drift Machine]

Does anyone know anything about destroking the KA? Is it really beneficial? Some guy was saying that you can use a L20 crank(fully counterweighted) to destroke the KA to a 2.2 Liter. But how, if any, would this improve a NA KA engine? Because it would make it undersquare? I don't really know any knowledge would be very helpful.

[SSS]

I believe the motor would still be just oversquare, but it would rev out higher. to be square the motor would need a 89mm bore by 89mm stroke (ie SR20).

[S14Zilvia]

I'm not very knowledgeable on this type of thing, but the advantage to a 2.2 liter KA would be that it would rev higher and probably have less harmonic issues at high rpms. These are just my assumptions though.

[_dk]

yes, destroking an engine is generally done in the interest of making higher RPM possible.

there *used* to be a fantastic paper on rod length:stroke ratio and the positive/negative effects of moving in either direction on the web, but apparently it's gone missing, so you'll have to do with google's cached version:

http://216.239.33.100/search?q...UTF-8

this page:http://www.courtesyparts.com/nismo/s13/s13_1.htmlsays KA24 connecting rods are 165mm, center-to-center;so a stroke of 96mm gives the motor a rod:stroke ratio of ~1.719:1

as you can read on the cached copy of the panic tech paper, this is just short of what some consider the "ideal" of 1.75:1, meaning yeah, there's probably a few hundred RPM, and a little engine longevity, to be gained by destroking.

can anyone confirm that the L20 crank can actually be used for this purpose? that'd be a nice motor to have rebello build...

ohyeah, hi, i'm new. i don't actually own a 240/sil yet, but hopefully that'll change tomorrow when i head out to trade my vw gti-16v on a green base-model S14.

[Drift Machine]

actually I found out that the L20 wasn't interchangeable without some work

[keepingthe240]

http://forums.freshalloy.com/u...84134

[raging panda]

I have also been pondering the destroking of a ka24. I was wondering if you were able to somehow deck the block, could you possibly shorten the stroke that way, maybe by shortening crank stroke and rod length? I really am just shooting in the dark here, but it was just a thought i was throwing around in my head. I am really trying to keep a ka under my hood for passing visual checks and what not, and i'm trying everyting i can to get some horsepower. I dont have the money, only the imagination.

[GodzillaFan]

the main point of the l20 crank would be the full counterweights, allowing you to rev higher, and it would make the KA MUCH smoother. It would be possible for a GOOD machine shop to modify the stock crank and destroke it... but not a good idea imo.