KA24DE Bottom End Modifications

Advanced discussion of improving KA-T components
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superDorifto
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Re: KA24DE Bottom End Modifications

Post by superDorifto » Wed Jan 29, 2014 10:44 am

Dont take my remarks as me being derogetory or condesending....

The orignal point of this thread was to discuss potential CHEAP/Overlooked options to get a FCW crank from an LB20 into a KA. The numbers don't lie, this cannot be done cheaply, and I stand by my assessment that what you're talkign about doing will be just as costly - no other value judgement on wheater it is worth it or not.
All I'm saying is there is a reason nobody has stepped up to the plate, you can get more bang for your buck with other mods. I'm not trying to make your build the same as everyone elses...just trying to keep people grounded in reality.

Any mod is possible with enough money. Its your project, do what you want and take lots of pictures, so we can keep people coming back for good technical knowledge.

sil-coupe
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Re: KA24DE Bottom End Modifications

Post by sil-coupe » Fri Feb 07, 2014 8:54 pm

I linked a bunch of info about these modifications in the last few pages of my build thread. Check it out, it may be helpful. I'd like to see someone stateside do this. I was going to do it but like other people have said, the cost to benefit ration is very high and not on the good end.
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Re: KA24DE Bottom End Modifications

Post by RosadoRacing » Tue Feb 11, 2014 7:26 am

why the hell would anyone wanna destroke the ka. the torque is great and the stock crank has been revved to 8500. ati damper n good balance is the key. look at some of the guys dyno sheets 500hp/500tq at 5000rpm now why on earth would u wanna rev to 9 grand? b18, sr20 don't make those numbers till 7000+ rpm

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Re: KA24DE Bottom End Modifications

Post by Bubba » Tue Feb 11, 2014 9:25 am

I like the idea of a balanced crank and high revs but I have to agree with RosadoRacing here.

The idea sounded great until I remembered I love torque and can get another KA for dirt cheap.
My car is dead stock.... ish

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superDorifto
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Re: KA24DE Bottom End Modifications

Post by superDorifto » Wed Feb 12, 2014 3:23 pm

RosadoRacing wrote:why the hell would anyone wanna destroke the ka. the torque is great and the stock crank has been revved to 8500. ati damper n good balance is the key. look at some of the guys dyno sheets 500hp/500tq at 5000rpm now why on earth would u wanna rev to 9 grand? b18, sr20 don't make those numbers till 7000+ rpm
You do it for rev's and ultimate power potential. You hit the nail right on the head. The smaller motors need more revs to make a comparable level of power as the KA. Its a trade off, do you want faster response and more top end power, or more torque down low and no ability to rev past 7500?

For useable street power the KA is hard to beat. However, a higher reving motor with a ginormous turbo would yield more power, if it could live through the stress. Thats part of the reason I gave up. I couldn't justify a use for this frankenstein....what the hell was I going to use it to do? drag racing is about the only thing that comes to mind.

That, and it would have been pretty cool to have a KA rev to 9K.

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Re: KA24DE Bottom End Modifications

Post by pakii-afa » Thu Feb 13, 2014 11:07 pm

sil coupe. the links you gave me are of older l\z blocks with ka heads fitted onto them. it works but my objective is to use a sohc head with a block that has piston cooling jets (either a 240sx block or a theoretically much more preferred frontier block) so the issue with that becomes the crank main journal width since the l20b crank mains are wider than the ka mains.

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Re: KA24DE Bottom End Modifications

Post by supakat » Fri Feb 14, 2014 4:52 pm

Import DPS spun a stock crank to 10k until it cracked.
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sil-coupe
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Re: KA24DE Bottom End Modifications

Post by sil-coupe » Fri Feb 14, 2014 8:12 pm

I was SERIOUSLY considering a "destroked" motor, however the complications and ultimate cost led me in the direction of the L/Z20/KA hybrid. The reason... Destroying the ka is also going to decrease the displacement. In my eyes the ONLY benefit of using the ka block is that you can use super long rods decreasing piston side loading. In that case you need custom rods... Local cnc shop quoted me $2000.00 for a one off set of four. Too expensive! Benefits of the Lz/ka hybrid is readily available parts and a shorter deck height... Lower center of gravity by about two inches! I have no doubt that the oil passages are similarly routed in the L/z motors as they are in the ka. A machine shop could machine the flat spots and tap for the piston cooling jets.

The hybrid engine links were provided for a easier less expensive and proven route.

Now regardless of whether or not this is practical in any configuration, whether pure ka or hybrid, this build whenever someone actually succeeds stateside is a benefit to the community. In the end its the builders money and no one else. I give mad props to anyone thinking outside the box and even more respect to those that stick to it and build their dream!
"Build it, have fun with it, break it, and rebuild it." Brian Parker
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Re: KA24DE Bottom End Modifications

Post by pakii-afa » Sun Feb 16, 2014 7:03 pm

thats one of the major benefits to having a ka block is having a super long rod combo for more dwell time, which tuned right can be a cleaner burn, less side loading and even more rpms that longer rod motors like. the ford 5.4 169mm rod with ka piston should work well on a 86mm stroke, its close to f1 territory (2:1) but thats where they develop such high rpm power, add a turbo and some timing youre good to go. tune is obviously your major concern after you have the main journals figured out which is my biggest issue at the moment.

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superDorifto
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Re: KA24DE Bottom End Modifications

Post by superDorifto » Mon Feb 17, 2014 5:41 am

$2K local seems pretty high, I got a quote from a shop that does NHRA rods, and even with MP59 rod bolts it was under $1K.

You definately need the custom rods because the L series rod jounals are .200" too small. I spent a day with my machinist going through every catalog he has access to, and there are no off the shelf rods with all of the right dimensions (Big end, small end, and center to center distance)

With the KA's new found ability to rev, it is going to need attention paid to the head/valvetrain, I guess you could leave it stock and just throw in some double valve springs to combat float? But to me that seems like building a tiki hut on a freshly poured foundation.

Who is going to be first to step up to the plate?

My normal KA-T still hasn't even been driven, its going to be a good long while before I'm rebuilding again.

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Re: KA24DE Bottom End Modifications

Post by sil-coupe » Mon Feb 17, 2014 8:48 pm

The $2000 quote was for cnc billet aluminum rods. Figured that if I was going for high revs, might as well have less rotating mass for increased response on the "smaller" engine.
"Build it, have fun with it, break it, and rebuild it." Brian Parker
"Shiny fittings are for ricers, race cars have zip ties and hose clamps." Barton Black

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superDorifto
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Re: KA24DE Bottom End Modifications

Post by superDorifto » Tue Feb 18, 2014 8:07 am

Ahhhh,

I had a quote for forged Steel Bilet, I think 4030? Basically like the old school Crower Rods.

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Re: KA24DE Bottom End Modifications

Post by pakii-afa » Wed Feb 19, 2014 2:08 am

the ka is 34 mm pin height right?
so l20b stroke, ford rod, ka piston
43 + 169 + 34 = 246, correct? 1mm short of deck height?
the crank mains are .200' wider, i believe the con rod big end are the same between the two cranks?
ford rod big end is right demension, small end needs to be bored out.

am i missing anything? or am i to tired and none of this makes sense?

and for the valve train id be upgrading it to perform within new rpm capabilities, stock would probably blow up at 9500rpm lol

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