KA24E/DE Pistons????

[sinner720st]

Does anybody have any ka piston out there that they would be willing to part with... i want to get the compression up in my naps-z 24.... let me know please.

 

and also if anybody has done this minor swap, just wondering if everything goes smooth. or what power gains from z24 8.4-1 compression to ka 9.4-1ish

 

Thanks

[MicroMachinery]

KA-E and KA-DE pistons give you different compression ratios(they're not the same piston).

[sinner720st]

i know the de piston would be less dish more compression. i read the numbers somewhere i just forgot them. im pretty sure the old napz motor could handle higher compression i guess the head design is anti pinging just have to have a head gasket on hand for that saturday repair

[MicroMachinery]

Actually, it's the E piston that gives you a higher compression ratio.

[sinner720st]

oh either ones would be fine. i have just dumped a bunch of dollar bills in cam carb header and dont feel its getting its full potential i think if i get higher comp and maybe reach into my head with a dremmel tool i think it would be a pretty good feeling

[XeroX]

gota love posts with pointless comments...

 

http://en.wikipedia.org/wiki/Nissan_KA_engine

 

that should give you the info u needz

[datzenmike]

The The KA E piston has a 2.8cc dish with the exception of the very early 240sx motor which had a very mild 2cc dome in it to achieve a 9.5? compression. The DE head is about 10-12cc smaller in volume so it has a larger dish than the E pistons.

 

If you are using 240 pistons you must use the 240 rods too. If using the Hardbody pistons it's dealers choice on the rods, Z24 or KAE, although the Z rods look thicker/stronger. DE rods are particular to the DE block and won't fit the E or Z motor. DE pistons may only work on the 240 rods and not the Hardbody/Z rods so find out.

 

2.8cc KA E pistons in an otherwise stock Z24 engine will give a 9.52 compression

[sinner720st]

well that sounds good to me. i would probably just opt for the hardbody piston, if they are offered with rods cool, if not whatev. Now that thats settled does any body close to portland have any, or maybe bring them to canby and hunt me down let me know. thanks datzen mike and Xerox for the info

[medengines]

I have used the KA24E pistons on current Z24 combo. Alot better power wise..wakes up motor and you can definately feel a difference!!

I just used the Nippon Brand on Ebay they are cheap! 70 or 80 bucks for the set with the rings, i forgot exact price. Worth it if your after more power and youve got the motor apart.

[sinner720st]

oh e bay. thats a good idea. i dont have the motor apart, i just did my timing chain a couple weeks ago and head gasket a couple months ago.... when to do swap?

F-it i will just get the piston and just do it in a weekend pluss just because im bored.

 

so the power is noticeable. because so far the only thing noticeable for power making was ditching hitachi for weber. cam n header not too noticeable, the speedo goes pretty fast though and i get worse fuel mileage, so it must be doing something.

 

oh DATZEN mike or any body else i forgot to say that im running the z20 head for higher comp and better gasket life already, perhaps know ratio of the top of your head??? if not do you still think i can run regular gasolina?<div><br></div><div>is the conrod diameter for crank the same on both rods? can ka24e rods go on my crank?</div>

[datzenmike]

If you have a Z20E head from a 200sx then no compression change.

 

If from the Z20S like the '84-'86 720 Mileage Option motor the compression would be 9.49 if used on a stock Z24. So don't add KA pistons or the compression will exceed 11 to 1.

 

I see no advantage to the Z20 or Z22 head... they have smaller round intake ports than the Z24 head.

[sinner720st]

i think it is the z20e head because there are what look like injector bosses/ cutouts in the port openings. the ports are smaller i need to hawg them out or resurface my 2.4 head. the biggest advantage to the z20 head was i found it on craigslist for fifty bucks, looked at it i could almost see myself in it, it was so clean. and it still had very distinct machine marks from it recently being resurfaced. blew head gasket on thursday, got new gasket and head on fri/sat and drove the pickup to work on monday. if it was the other z20 head that would be ultra cool. thanks again for the knowledge. you sound like a naps encyclopedia. im glad i joined the rat club

[datzenmike]

Here's what to look for. The regular Z20 head has round combustion chambers like this:

 

 

The Mileage Option 720 Z20 head has smaller chambers with two small quench areas on intake and exhaust sides. I suspect that this head is also used on the Z20S motors used in the '80 A10 car. The Z20S uses a dished piston to lower the compression to around 8.5 or so.

 

 

If you have this head and install on a stock Z24 the compression would be 9.472 or perhaps slightly less as I don't have an accurate chamber volume. Safe to say not over 9.47

 

I have suspected that this head existed for several years before someone sent me a picture of one. It was a combination of knowing there are flattop and dished Z20 pistons and yet the compression ratios are basically the same. The only explanation is a smaller combustion chamber. Even Jason Gray mentions a Z head that is 45cc which is way way smaller than any Z22 or Z24 truck or Z20E head I have ever measured.

[sinner720st]

that combustion chamber is very tight on the fuel saver. i deffinately have the z20e head. about those small round ports; i had to bolt me rectangle intake manifold back on, so i did minor porting at the opening of both head and mani, made one more round and the other more square. there isnt much room in there with the water jackets so damn close...

 

i forgot just how close those valves are, makes me leery of adjusting the clearance to tight on rocker arms.. clank clank and done.

 

could you explain the "small quench areas"? not too sure what that means. thanks

[datzenmike]

Any time the combustion chamber does not extend out to the edge of the cylinder wall there will be an area where the piston comes up, and almost touches it. This area where the piston and head surface is known as the quench area, also known as pinch area too. The distance between them is roughly the thickness of the head gasket. An L series peanut head, (named for it's shape) is a good example of a closed chamber head with lots of quench.

 

Here is an open chamber W-58 head with combustion chamber extending out fully to cover all of the cylinder.

 

 

Here is a closed (or peanut) chamber W-58 head.

 

 

Interesting things happen in a quench area at TDC. Any air is trapped between the rising piston and the head surface and violently pinched out into the open area. This causes beneficial turbulence and swirl that homogenizes the mixture and draws heat away from any problem hot spots that could lead to pre ignition. Generally a quench area head will run cooler and besides being more 'ping' resistant even with a higher compression raito, will burn the fuel more efficiently.

 

.

[sinner720st]

wow that is very interesting. i just love learning new things about cars. not trying to be a smart ass at all but if you have a z24 bore i think 85mm (dont quote me this is just an example) and the z20e head that i have on my truck is oh 81mm bore combustion chamber, then that would inturn mean there would be about 2mm of "quench" area around the cmbustion chamber.

(i kind of just confused myself, hope you know what i mean. im just bouncing some made up theory off of you that i just fabricated right now)

[datzenmike]

Z20-85mm

Z22-87mm

Z24-89mm

 

I measured my Z heads a while back and couldn't find any difference in chamber diameter. The Z20E, Z22S and Z24 were so close to the same as to make no difference. But yes, technically an 85mm head on an 89mm bore would have a 2mm ring of quench around the rim. 2 mm is very small, just under 0.080"and would have next to minimal effect.

 

Here are two styles of chevy combustion chambers. The older top one does have some quench on one side.

 

 

This one is better thought out and runs less advance, makes more power using less gas.

 

 

 

To be most effective the piston should be a flattop design as any dish reduces the pinch area.

 

 

.

[sinner720st]

huh. so one of the reasons for me buying the z20 head was for higher compression, and if the combustion chamber dia. arent really any different then im not getting any power gains to speak of (none noticeable anyways). in fact its prob hurting because of the small ports. on that subject have you ever ported a z head, if so were you nervouse about breaking through to the water jackets, or is there enough material there to round out that near 90* bend by the valve

[datzenmike]

I ported this one, a Z24.

 

 

I went crazy on it and ground down the bend in the bottom of the port. Another area was the bottom of the valve seat where it meets the aluminum of the port wall. Every one had huge burrs on them and very rough casting seams in them. I ground them down and blended into the steel seat

 

I would get a Z24 head, they are already larger ports and the Z24 intake matches it. The Z22 would strangle it at high speeds but would have great port velocity and low speeds.

.

[sinner720st]

i still hav emy old z24 head i just blew a head gasket with it so it prob is not flat anymore. i should go all coked out on that thing and make it breath better. then swap, i would prob notice my cam better. but you did not worry about water jackets under ports?

[datzenmike]

Most of the metal removal was in close to the valve right on the sharpest part of the bend. Maybe thicker there. Otherwise just remove burrs and casting lines. I smoothed it by tearing strips from an 80 grit belt sander and see sawing through the port and valve opening.

 

 

.

[hang_510]

I see no advantage to the Z20 or ...

what about with a U67? ONLY if it would bolt to a Z24 block. more crazy ideas! :frantics:

[sinner720st]

very nice head work. i dont know about the sandpaper thing though. i heard you want a bit of roughness to give it some fuel mixing turbulence. i was also thinking of making or buying some sort of dial caliper or other measuring device to measure thickness of port to water jacket. but if staying close to valve i would prob be fine. it would be my first port job. if i mess it up i still have the z20 head until i find another z24 (millions in wrecking yards). as for the u67 i have heard that before but dont know what it is. if its worth it you can make anything fit