z24 vs ka24e heads

[breadbox]

This is the first installment before I get my tools back to start comparing. Just make notes on what you see.

Z24







KA24e




Modified by breadbox at 12:06 PM 10/26/2009

[seang]

Note the naps-z's duplex timing chain. If the solid lifters of the naps-z could somehow fit the ka24e, that would be badass. Definitely more performance oriented than the hydrolics.

[breadbox]

You can also see the timing link on the ka, which is neat that its up.

Z24 is 2 valves per cylinder

Ka24e is 3 valves per cylinder.

But the head bolts look about same on both, so hopefully they will swap directly water paths hopfully line up too. More on that later.

[breadbox]

Also, as I get more into this, you guys can request pictures of either motor.

Back of both heads look similar too.

[bignasty720]

how did the swap go? im looking in to doing the same but i cant find one single wright up or any good pics?

[breadbox]

I have been selling my old daily and trying to get my new 89 coupe daily running and inspected, I keep getting caught up else where.

I want to tear down the motors, but I haven't had time. Once it starts there should be plenty of pics and details.

After I findout why my 240 is overheating and not shifting right I will do it up.

[seang]

Hope you don't mind if I add a few pics. I didn't take them, but they are mine now since I copied them to my photobucket.

This is the intake side of a KA-E head....[IMG][/IMG]

....and two naps-z heads. Z24 is on top and Z20 is on the bottom.[IMG][/IMG]

I would like to know the stock combustion chamber volumes. With all this talk about swapping heads and what not, that is important. If not vicariously, then it is singularly important to measure them when doing any head work just so you know that they are all equal.


Modified by seang at 1:28 PM 3/7/2010

[flinterman2000]

From all I've read, the KA and the Z24 has the same size combustion space as they carry the same compression ratio and same cc. They flow better due to the extra valve and size of the ports. The Z20 wold increase the compression as it has a higher compression ratio and smaller cc. The actual sizes of the compression spaces I can't say.

[seang]

Early KA-E's had flat top pistons and 9.1:1 compression (and 150hp). Later KA-E pistons got a 2cc dish and 8.6:1 compression (and 140hp 240sx, 134hp Hardbody Truck).

I thought Z24's had a 15cc dish and 8.3:1 compression. This leads me to believe that the Z24 has a smaller combustion chamber volume because a 15cc dish on a KA-E would reult in less than an 8.3:1 static compression ratio.

I inferred this ^ through the fact that 2cc already dropped compression from 9.1:1 to 8.6:1, so obviously a whole 15cc would drop it well below 8.3:1.

[flinterman2000]

The dish in the pistons, are they humped or bowled dishes. In either case the compression space remains the same as the compression ratio is affected by the dish in the piston.

[seang]

The dish in the pistons, are they humped or bowled dishes. In either case the compression space remains the same as the compression ratio is affected by the dish in the piston.

The dish is recessed into the piston like a bowl.

Are you saying that the volume of the combustion chamber doesn't directly affect the compression ratio? You have to know what that is to even calculate the static compression.

[flinterman2000]

The dish is recessed into the piston like a bowl.

Are you saying that the volume of the combustion chamber doesn't directly affect the compression ratio?

No. What I'm saying is in this case the combustion chambers are almost identical and that is why the dish is what changes the compression ratio. I can't remember how to calculate the volume of the combustion chamber. Learnt it in school back in 1986.

[seang]

Here is an article (not a competing forum) about CCing the chambers. Pretty straightforward. http://www.cosworthvega.com/cc_an_engine_GEC.html

I remember reading an article where an owner was rebuilding a Corvair air cooled flat-6 for a light aircraft, and it turned out that the stock heads had casting differences and that the chambers were questionably different from each other. I was like Nissan heads seem to be of decent (better)quality, even the old ones.

I just read that the OEM KA-E chamber checks in at 65cc. I have also just read that most naps-z and L-series are 45.2cc. These are just quick maybe-facts that I got off Google by searching "ka24e chamber volume" and "naps-z chamber volume."

Here is also one of many compression ratio calculators:http://www.csgnetwork.com/compcalc.html


Modified by seang at 9:15 PM 3/10/2010

[breadbox]

So what does this mean in simple terms? ka24e will flow better? so I should turbo every kae I have.

[seang]

So what does this mean in simple terms? ka24e will flow better?

Obviously, the KA-E head flows better than the Z head, especially on the intake side. Exhaust sides for ka-e and naps-z look very similar and you can even use a ka-e turbo manifold on a naps-z, even though the ports are a little different.

I was messing with that compression ratio calculator, and found that a 15cc dish with the ka-e head would get you somewhere around a 7.5:1 compression. I don't even hear about boosted engines going that low.

As far as what you should turbo, I can't say. I'm not the ultimate guru of this s***, I just like boiling down a few facts if I can. I have seen pics of turbocharged and supercharged naps-z engines, so you could probably turbo one of those if you wanted to. It's up to you in the end.
Modified by seang at 12:52 PM 3/17/2010

[breadbox]

All I know is I plan on building and turboing the hell outta a KAe.

[seang]

A properly built single cam KA will be bulletproof. Love the ka-e. I still like the naps-z, too; but only as a friend.

[flinterman2000]

I don't even hear about boosted engines going that low.

At low rpms it will cause some problems but will prevent things like detonation and such like, regardless of intercooling at or above 30psi anywhere from 3500 rpm through out the range.

[seang]

At low rpms it will cause some problems but will prevent things like detonation and such like, regardless of intercooling at or above 30psi anywhere from 3500 rpm through out the range.

I think the early z31 turbo's had something around 7.5:1 or 7.8:1 compression, then they upped it a bit later on for, like you said, low end response.

[breadbox]

i'd be awesome to build one that low and bi-sequential turbo it.

There is a guy on KA-t.org that was building one and testing modding testing but IDK if it ever got done up right.

A properly built single cam KA will be bulletproof. Love the ka-e. I still like the naps-z, too; but only as a friend.

This had me laughing for real.

sorry nap-z your younger sister is a bit better.

[seang]

I was reading about sequential twin turbos (on who else but wakopedia) and there are several cars that came from the factory with this setup. According to the article: "With recent advancements in turbocharger design, and reductions in lag this has made possible, sequential twin turbo systems have fallen out of favor because they are seen as unnecessarily costly and complex."

I would say that if you really want to get nitty-gritty, get a twin scroll setup. That seems to be what is lusted after nowadays. Expensive, too.

If I were boosting my truck, I would probably get a JGS log style manifold. Boring, I know.

One thing I lack on turbo knowledge is the trim sizes. I don't know s*** about that.


Modified by seang at 2:46 AM 3/28/2010

[flinterman2000]

One thing I lack on turbo knowledge is the trim sizes. I don't know s*** about that.

Most manufacturers supply info on flow and a graph to show where the turbo spools out. No more boost. The trim sizes are an integral part of these diagrams, and will affect the size of intercooler and piping to use.

[breadbox]

More Pictures. This a KA24e.

[breadbox]

NAPZ24

[breadbox]

I had a thought today. Happy Valentine's To all, hope you have a nice day.

But When putting the head on the Z24 we kept grabbing KAe HGs instead of the 1 z gasket we had other than the original, which I had considered throwing back on.


Here's the thought.

We noticed the head gasket's overall shape in relations to the cylinders was the same, but there are differences in water jackets and the oiler spot/IDK what its actually called. The z24 has the oil spot separate from the bolt hole and the KAe has the oiler spot and one of the head bolts in the same spot/opening on the gasket. Front cover part of the gasket is identical on both.

I want to see if I can take the other z24 motor and see what it takes to get the KAe head on.

I hope I can use z24guides with a KAe sprocket, chain, and sprocket on the z24 block and it line up on the kae head perfectly. Gotta look into what the oil pan situation is.

its getting warmer, bout to be the season to sit in the garage comfortably.

[alexkas1977]

Hi, guys
I`ve read this thread in forum and i`m gonna make some questions clear.
Compression of Z24 engine with 15 cm3 dished pistons is about 8.3:1, so with pretty siple calculations we`ve got that the combustion chamber volume of z24 NAP-Z head is 56cm3. Head gasket volume (1.5mm thikness) is 9.3cm3. So overall combustion chamber = piston chamber + gasket chamber + head chamber = 81.54cm3
Exact fomula in this case ((15+9.3+56)+597.23)/(15+9.3+56)=8.32
I`ve made some changes to my engine by setting early Hardbody KA24E 0.5 ovesize (slightly dished ~2cm3 ) pistons and machining of 0.7mm from head. I`ve got 10.4:1 with good mileage and bottom end torque. But flow of z24 head at high RPMs is awfull. So this engine revvs bad.