Ka22det

[blackmarkit]

I hope there already isn't a post about this. I'm trying to build a destroked ka. It's been talked about in a few different places I just don't know if anyone here has talked about it. Anyways the thought is to put a l20b crank in a z24 or ka24 block and have a 89mm bore with the common sr20 stroke. The ka head out flows the stock sr20 head and has a better valve train than the sr20. Anyways tonight I dropped the l20b crank in a ka24de block and realized the thrust bearing on the l20b is 32mm and the ka is 27mm. So I was hoping somebody could measure the z24 block and tell me what the trust bearing width is.

[flatcat19]

I've seen it talked aboot elsewhere.

 

The general consensus that I have read came to the conclusion that it didn't work.

I don't remember seeing a single thread where someone had done it and/or yielded positive results.

 

 

If you're willing to build a better mouse-trap, were all watching.

[TFM1066]

Yes it works, you can run the 16 valve head on the Z-24 block, same bore spacing and head bolt pattern. You really don’t want to use the L20B crank to much rod / stroke ratio and a heavy piston. You’re better off using a Z-22 crank. Assuming that you stay with the 6.5 rod. I have done all strokes, L-20B, Z-22 and now moving up to the Z-24 stroke. I started with the L-20B stroke due to the cubic inch rules in the racing division that I race in.

 

Although some here (ratsun) may say it can’t be done, It can I’ve done it works just fine.

 

You use the KA T-chain with the Z-24 chain guides. It all fits. The only thing that takes time is modifying the T-chain cover (Z-24) to the 16 valve cly head.

 

I understand that many may say this can’t be done but I have been racing this set up for a few years. Remember that Datsun/Nissan is the small block Chevy of the Asian world and many parts are interchangeable. The Z and L blocks and cranks are far better than the KA blocks and cranks for many reasons that I won’t go into.

[datzenmike]

Lol... yeah, the KA cranks are way different than the L or Z series. Rod bearing are the same. Main bearings are was smaller width. I fit an L20B crank to a KA main cap girdle to see once. The thrust bearings are so narrow the L crank will move 1/2" forward and back. Look at the bottom KA mans width and how wide the L20B crank journal is.

 

 

OK if you stick an L20B crank into the Z24 block the 1/2 stroke = 43, the longest rod is the KA or Z24 at 165mm, the KA or Z24 piston pin height is 34mm... this totals to 242mm which is almost 5.5mm short of the Z24 block deck. This adds over 30cc to the combustion chamber. I used the KA piston to limit the dish and the compression was 5.537 on a 2 liter KA head motor.

 

Getting a custom set of rods that are say 170.45mm long to bring the piston to the top of the block .... carry the 2 is.... 7.36 compression.

Custom rods 2mm longer and mill the top edge off the KA pistons to make them flattop and get rid of the 2.8cc dish and the compression jumps .... to.... oh 7.60.

 

Looks like custom pistons with a dome might help here.

.

[datzenmike]

Yes it works, you can run the 16 valve head on the Z-24 block, same bore spacing and head bolt pattern. You really don’t want to use the L20B crank to much rod / stroke ratio and a heavy piston. You’re better off using a Z-22 crank. Assuming that you stay with the 6.5 rod. I have done all strokes, L-20B, Z-22 and now moving up to the Z-24 stroke. I started with the L-20B stroke due to the cubic inch rules in the racing division that I race in.

 

Although some here (ratsun) may say it can’t be done, It can I’ve done it works just fine.

 

You use the KA T-chain with the Z-24 chain guides. It all fits. The only thing that takes time is modifying the T-chain cover (Z-24) to the 16 valve cly head.

 

I understand that many may say this can’t be done but I have been racing this set up for a few years. Remember that Datsun/Nissan is the small block Chevy of the Asian world and many parts are interchangeable. The Z and L blocks and cranks are far better than the KA blocks and cranks for many reasons that I won’t go into.

 

We're all fairly equal here... so use Arial font and 14 size from now on. It's easier to read.

[EricJB]

I have been thinking about a Z24 block/ Z22 crank/ mitsubishi 91.1 pistons. If I did my math right, the mitsu piston has more pin height, and give the desired deck height. I have a single mitsu piston, just haven't tried it yet.

[flatcat19]

Given the numbers Mike posted, why?

 

 

That's pretty much the basis of all I had read on it

No one found a combo that worked with gain.

[EricJB]

With a workable deck height, and an L head, the destroked/ big bore/ long rod combo would behave more like a car than a truck. But it is still a 2.4. I think the mitsu pistons have a 1.42 pin height. I.m at work right now and all that stuffs at home.

[bonvo]

my question why would you want to go down in displacement? havnt you heard the saying "there is no replacement for displacement" well its true some say that technoligy is the replacement but think about it you add that tech to displacment and you get more power then lower displacement so again why go down in displacement

[HRH]

One reason is to fit within certain rules for racing.

[flatcat19]

I think the OP's appeal in losing displacement is that he will be gaining rev's by squaring up the motor.

 

I don't see the pro's outweighing the con's with this though.

 

I am, however, interested in what EricJB finds with those Mitsubishi pistons though.

 

[EricJB]

Compare an L18 to an L20. Same bore. L20 has more torque. Put a little rod ratio in the L18 (L16 rods) and a decent head and it screams like a dirtbike. In a light car with low gears, this makes for a good time. A KA with some taller gears pulls like a big block, but tops out sooner. It just depends on driving habits, and preference I guess. As flatcat says, just trying to square it up as, IMO they are a little over stroked. If you could bore one to 96mm, I would be OK with that. But thats not going to happen.

 

Edit. OK home now. The mitsu pistons have a 36.01 pin height. The pin dia. is .866, so the rod ends would need to be bored.

 

36.01 (piston) +165 ( rod) + 46 (Z22 stroke/2) = 247.01mm

A Z24 block is 247.45mm, and .44mm is .017" deck height. After you deck the block for cleanup, you would have a bit less.

 

91.1 x 91.1 x 92 x .0031416 = 2398.69cc's so it's still an LZ24. The rod ratio is 1.793. Since it's not on the Jason grey list, If it works, do I get to name it?

 

OK DatzenMike, please help me out with the comp ratio's. L heads. The pistons are flattops.

[blackmarkit]

Ok so I found out the z24 block uses the same main bearings so it will work. As for the coming short I the deck you can use a ford 5.4 connecting rod which is 169.0878mm with the crank and piston pin height it comes out to 246.0878mm. 1.3622mm short of the deck. Compression would be 9.29:1 the rod ratio is high a 1.966 but that's why I think it would make a great turbo motor. The long dwell times would allow time to charge the cylinder sence it's under pressure. As for the question what is the benefit. Well sence the l20b is fully counterweights and can handle around 9000 rpm vs the ka which experiences vibration at 7200rpm and case premature wear. There's is a formula which CID x .5 x max rpm / 1728 = cfm

Granted that is 100% ve. So you multiply that by .85 which is 85% ve. As you will see the smaller motor will make more power.

[blackmarkit]

Also the long power band would leave you in boost longer. I wanted to use the ka24 de block because of the piston oil squirters but I guess that could be machined in a z24 block. Also ford 5.4 forged rods can be bought for $75 eAch on summitracing ka forged piston can be bought for around $450. So for under $800 you would have a fully build bottom end. Of coarse cams, springs and retainers would be a must for that rpm.

[blackmarkit]

This would also work if you bored the l20b block to 89mm and used late z22e rods.( 149.5mm) total height would be 226.5 and l20b deck height is 227.45mm only problem is oil returns in head and extra cooling port on back of block. Oil ports would be easy to run external tho. Rod ratio would be 1.73 which would be more desirable for n/a

[blackmarkit]

Compression on the l20b block would be 9.36:1

With cast pistons and z22e rods this could be done very cheap

[Rustina 510]

Very interesting.

[EricJB]

I think the big end of the 5.4 is too big. (2.240) Most of the domestic stuff is.

[flatcat19]

It might help know which Ford rod you're using.

[blackmarkit]

Your right that's the rod journal bore the bearing size is 53mm but still to big with the Datsun right under 50mm. They do sell 1mm undersized but still not enough. But the l20b block will still work and ill keep looking for another rod.

[blackmarkit]

Found a aftermarket vw rod

Legth 6.620"

Big end rod journal size 1.99"

Piston pin diameter 21mm

 

Looks like a good match. Compression would be 8.56:1

The problem is the price. $210 each

[blackmarkit]

Also looks like you could use some Honda h22 rods on the 227.45 deck height. I think a z22 block bored out 2mm (safer) with z22e rods or Honda h22 rods and ka24de pistons all on the l20b crank. The h22 rod would have to be bushed on the prison pin end.

[datzenmike]

I have been thinking about a Z24 block/ Z22 crank/ mitsubishi 91.1 pistons. If I did my math right, the mitsu piston has more pin height, and give the desired deck height. I have a single mitsu piston, just haven't tried it yet.

 

 

Edit. OK home now. The mitsu pistons have a 36.01 pin height. The pin dia. is .866, so the rod ends would need to be bored.

 

36.01 (piston) +165 ( rod) + 46 (Z22 stroke/2) = 247.01mm

A Z24 block is 247.45mm, and .44mm is .017" deck height. After you deck the block for cleanup, you would have a bit less.

 

91.1 x 91.1 x 92 x .0031416 = 2398.69cc's so it's still an LZ24. The rod ratio is 1.793. Since it's not on the Jason grey list, If it works, do I get to name it?

 

OK DatzenMike, please help me out with the comp ratio's. L heads. The pistons are flattops.

 

Correct me if not right...

 

Piston diameter is 91.1mm

Pin height is 36.01mm

KA or Z24 rod..... 165mm length.

Z24 block

Z22 crank

 

I get a 2397.44 cc motor. No decking, un-planed heads.

With open chamber L head....... 11.73

With close chamber L head...... 12.61

With KA24E (12 valve) head...... 8.726

[EricJB]

With some combustion chamber work on an open chambered head, and some ARP head bolts. It might live. But would a Z24 block hold up?

[72240z]

I read this thread bored and still dont get the point. It seems like a waste of time to me. I would venture this Frankenstein idea at best would still be found sub part to a ka24de in just about every area. especially if a person put 1/2 the work into the ka24de that you guys are talking about with the frankinmess.

 

Also I know its just an opinion but "A KA with some taller gears pulls like a big block" made me laugh lol.