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Z20 block ka head build

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Need help been trying to build z20ka24e hybrid but have many questions first starting with timing since the z20 is napz would you just eliminate 4 spark plugs and run a coil pack. Also how much should the z20 block be bored to ensure clearance of the ka valves. Any information helps

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If you're putting a KA head on, you just eliminated 4 plugs.

 

I have a feeling g your compression will be too low for this to be a good option. I can't find the thread I read about this.

 

 

Why not LZ? An LZ20 would be a 9.5:1 screamer.

Or, why not full KA?

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Compression will be low. From memory 7.9 with a KA head. You could mill the head down 1mm and this would remove almost 6.2cc and raise it to about 8.6. The timing chain has to be custom made anyway so extreme milling of the head won't matter. Before going this extreme mount the head with a used gasket and a blob of  modeling clay below the exhaust valve on the piston at TDC and rotate the cam by hand. Measure the thickness where the valve indents the clay and you have a rough valve to piston clearance. I'm assuming you are running the Z20E flattop pistons? 

 

You know about the head having an oil drain back hole that goes right into the cooling system of an L or Z block.... right? 

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I have heard about the oil drain not sure which one it is yet but I have new Pistons that are .050 over and the block is a z20s and I'm not sure if there is a difference in the e to the s Pistons

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So...do you have the old flattops from your Z20?

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Just wondering why you want a hybrid build? Do you have the latest bottom end too?

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The KA would have superior breathing but the L head would also be pretty good for only 2 liters. It (the KA) is also a cross flow head and would lend itself to a turbo better than a L head. Anything available for the KA engines would pretty much apply to this one as well.

 

Z20 and .5mm over bore with KA head would be 7.6 compression.

 

The above with 1mm milled from head................... 8.3

The above but also with 0.5mm milled from block.. 8.59 (this should still be just under the 0.3mm above the deck but strongly recommend checking valve to piston clearance)

 

 

The oil drain back hole is on the rear of the head.

 

 


Well I've ordered main and rod bearings.With the crank roughly in place I can loosely place the head on and start working out the timing chain length. Also check the head bolt lengths. One of theses KA heads I unbolted and I saved the bolts but I don't see them. The Z24 bots will work but I'll keep looking.

As the KA 24E had two oil drain back holes at the rear of the head and one is in the place of all L and Z heads, but the right side is directly over a coolant hold in the Z22 block and this will not do. I figure the copper head gasket will seal them both from each other but just in case I'm closing it off.

I made an 1/8" aluminum plug and hammered it tightly into the head about 1/2".
23headgasket006Large.jpg
 
Next I ground a groove into and around the bore about 1/4" down. This will help anchor the JB weld so it can't move up or down. Mixed, this stuff actually flows and fills into any cavity. Nice
23headgasket007Large.jpg
 
Pretty close to flat but I'll check with a straight edge. Now the gasket is well supported.
23headgasket008Large.jpg
 
 
Still have to weigh the head without any valve train. and when finished. I guess this is the last thing needed and I can start the valves as soon as I get the seals.
 
 
.
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So if I am using all of the z20 timing components where should all the marks be located

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Z20 and .5mm over bore with KA head would be 7.6 compression.

 

You have to address the poor compression. More homework.

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So, what's the point of Z20 block?? Only advantage I could even see is basically a de-stroked KA, Therefore making a "square" (ish) KA20DE....?

 

Well, guess what?

 

There is such thing as a KA20DE in Asian markets. Just order a Ka20de crank...? place in KA block and wahlah! You lost power!

 

I dont get it. :confused:

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Also, If you're just looking to simplify your 8-plug NAPSZ, just get a 4 plug Z20E head from a 200SX. Replace the EFI with your carb intake and run your current distributor....

 

Boom. 4 plug, NAPSZ with a carb.... 

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KA main bearings are narrower than the L and Z ones.If the KA20DE is true to form it won't work ... and why change the crank when he already has 6" rods and flattop pistons and 2 liter?

 

Simplifying a 8 plug NAPS to 4 plug is just wrong. The reason for the dual plugs is the ignition timing can be reduced to around 3 degrees. Less time for pre ignition. Why do AA fuelers use dual spark???? Coincidentally it also produces fewer emissions and the reason it's part of the NAPS system.

 

NO advantage to converting to carb at all. EFI is better starting, idling and running, hell it will run upside down! Floor it from idle and it accelerates without any balking. Better mileage too

 

 

If you had a Z20 block and wanted the ultimate breathing head then a KA would be my choice. The KA24DE would be 4 valve and better but a nightmare to convert. Only problem is the combustion chambers are for a 2.4 liter and toooo large for 2 liter.

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Original poster has been on in a week so it doesn't matter much.

 

 

My opinion is put an L head on it and enjoy.

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That would be a long rod 2.0 with 9.9 compression open chamber head. Surprised more don't do this.

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It does what every one wants on the cheap. Yet no one every thinks about it.

 

 

I'm not seeing the problem.

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That would be a long rod 2.0 with 9.9 compression open chamber head. Surprised more don't do this.

 

Sounds like a good time to me!!!!

 

 

And the point of the "KA20 crank" ... I meant to say... "If you're looking to use the Z20 block and KA head to create a de-stroked KA that's a 2.0 ... There is already a KA20DE in asian markets".

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That would be a long rod 2.0 with 9.9 compression open chamber head. Surprised more don't do this.

 

 

Why not do a Z20 with an closed chamber W58? Mmmmm side drafts and a cam with 100 octane sounds like a good time to me!!!

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Why not do a Z20 with an closed chamber W58? Mmmmm side drafts and a cam with 100 octane sounds like a good time to me!!!

Compression would be almost 10.37.

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Compression would be almost 10.37.

 

 

Sounds fun to me!!! Properly tuned, this wouldn't be a problem.

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Good gas, R1 carbs so there are no 'lean' cylinders, cold air intake in FRONT of the rad, oil cooler, cooler plugs, less timing.

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I built a KA24DE with around 11.4 it's staying EFI. Will be fun! Going in my friends 620

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