Z20 block, KA24E head

[TrueSlide]

Iam searching for this block as we speak. I know the z20 is fully counterweighted and the KA head will slap right on. I have a couple questions, I have been searching and searching. My head is kinda spinning, need to take a break. But anyways from what I read the z20 block the way it is needs to be bored. Something about valve shrouding and fuel? Can anyone clarify? Also is it good to use the z20 Headgasket and headbolts on this?

I remember reading it requires a KA truck type starter. And anytype of flywheel/clutch combo.

Iam jotting all types of info down, and planning ahead on what I want. So I can get started as soon as possible. I already tore the cylinder head down tonight and ready to get started.

[TrueSlide]

While surfing the internet trying to find which veichles have the z20. It came down to two different models of the z20. Any real difference in the bottom ends and the ability to use with KA?

1983 - 1985 Nissan 720 Pickup 2.0 (Engine: Z20)1980 - 1981 Nissan 200SX 2.0 (Engine: Z20E)

[Bigvinnie]

Iam searching for this block as we speak. I know the z20 is fully counterweighted and the KA head will slap right on. I have a couple questions, I have been searching and searching. My head is kinda spinning, need to take a break. But anyways from what I read the z20 block the way it is needs to be bored. Something about valve shrouding and fuel? Can anyone clarify? Also is it good to use the z20 Headgasket and headbolts on this?

I remember reading it requires a KA truck type starter. And anytype of flywheel/clutch combo.

Iam jotting all types of info down, and planning ahead on what I want. So I can get started as soon as possible. I already tore the cylinder head down tonight and ready to get started.

While surfing the internet trying to find which veichles have the z20. It came down to two different models of the z20. Any real difference in the bottom ends and the ability to use with KA?

1983 - 1985 Nissan 720 Pickup 2.0 (Engine: Z20)1980 - 1981 Nissan 200SX 2.0 (Engine: Z20E)

What you want is the block from the z20e(200sx front sump engines, truck engines are rear sump).

Valve Shrouding: when a valve is to large for the surface area of the piston, it will prevent swirl or lack of swirl for atomizing fuel to air. Shrouding by definition just means to cover.

Now if you want to keep the high rev of your 2.0 litre, without boring to 2.1 or 2.2 (which would probably I am assuming would be the maximum bore).You can order z20 valves (I believe)and use them on the KAE head with some actuall work done to the KAE head,(porting and welding.) Or use the Z22valves which I believe is the maximum that you can use for the 2.0 before valve shrouding... (Now some one stop me if I'm wrong)....The only differences that I notice between the NAPSZ head and the KAE head is that the KAE uses a lifter assembly while the NAPSZ head uses a rocker arm assembly. Hiegth between the 2 heads are the same......If you would like to bore instead, and keep the KAE head with the original valves the way you would want it you would want to get an L20B bore KIT, which I believe the maximum offered is 2.2 litres, But a 2.1 litre or better will be needed if you decide to stay with the KAE valves.Use the KAE gasket on the Z20 block.Use all the NAPSZ timing chain assmbly (sprockets and chains) for the KAE head.Use the Z20 head boltsI may have missed something.......

[deviousKA]

Im gonna go ahead and tell you now, the z22 block is the one that you want.... This is a medium deck height block same as the z20, but it siamesed bore with upgraded bore/deck cooling. The earlier non siamesed deck surface are more prone to heat between cylinders, prone to blow gaskets with larger bore. The z22 has a 1mm larger std bore (87mm) and can tolerate up to an 89mm. This bore size offers you many advantages in piston selection (think ka24). This is also the best way to get around any valve shrouding problems, and has nice oversquare characteristics (assuming you use an l20 or z20 crankshaft). L20 crankshafts are extremely easy to find.

z20e can be found in 81-82 200sx, these (like BigVinnie mentioned) do have some parts that you may want including the oil pan/pickup tube, crank and rods, and possibly the flywheel and motor mounts, starter motor (depending on what you want). These s11 z series motor mounts are easy to modify to fit in an s chassis, easier than making all new or modifying truck brackets. Z20s in the trucks is the carburated version, you will only find these in early 720 datsuns, 80-82. They were an option along with the 22 up untill around 85, and for one year the z20, z22, and z24 were all available in different option packages, z20 rare. The later model trucks 83-86 have about 80% z22 and 20% z24 in the latest models.

Z series valves will not work in ka24e heads, but the retainers and springs will work on the exhaust side.

Remember any time you build a ka/l/z hybrid your going to need an external inline thermostat, used nascar ones located in the upper radiator hose are a nice touch, also a good place to mount your coolant temp sensors if you have a custom intake manifold.

[Bigvinnie]

Im gonna go ahead and tell you now, the z22 block is the one that you want....

Devious you failed to mention that the z22 engines come halfweighted. It's just more parts that he will have to buy for the fully counterweighed L20b crank. Good call on the coolant passages of the z20......Why won't the Z valves work on KA24E head? I was looking at the valves and it looks as if it will just need some modifying.........

[deviousKA]

Yes true, the z22 crank is not fully counterweighted, would require more part sourcing. Far from expensive.

The Z valves are a different length iirc, and do not offer any advantages over a ka24e exhaust valve, they are all smaller.

You cannot fit a smaller diameter valve, not one that is very much smaller anyways.

[Bigvinnie]

Devious I was also checking the differences in the bearings and cap. It doesn't appear to have a strong bottom end compared to that of the KA. What would you say the maximum HP that could be achieved with the KAE head/napsz block hybrid?

[deviousKA]

The seperate cap L/Z bottom block was run in the lemans cars pushing over 600 hp turbo charged under prolonged race use. Seperate cap non girdle blocks have nothing but advantages over the japanese cast ka24 style, the blocks are high quality sand cast iron, it is not an issue.

Maximum? A setup like this professionally built for drag racing (max hp) could push near or more than 1000hp if you really wanted to do it. There are sohc japanese inline 4's pushing over 1400hp will huge forced induction and alternate fuel, maximum is only relevant to how far your willing to take it.

But knowing that you mean naturally aspirated, a hybrid sohc ka is capable of plenty, handful of 250hp already on the road with relatively basic builds, most carbureted.

Edit, I meant to say sohc 8v engines pushing over 1400hp, Toyota 22re.

[TrueSlide]

So for my bottom end that I want it would be

z22 blockz20 crank/rods/oilpickup tube/oil panKA24E pistons will fit on the z20 rods.

How much will that change compression and what would be it be at, I plan on running pump gas. Also I know alot of factors come into play, but Iam looking for atleast a 8k reving motor.

250HP would be great!

I appreciate all the help guys.

Well looks like Iam gonna start parts shopping.

[Chezedik]

Can this be done with DE since it just uses the idler in place of where the old cam gear used to be on the E?

[deviousKA]

Your compression is going to be relatively low with the sohc head and the 2.1l hybrid. If you want your compression up over 10:1 your going to need to look into some aftermarket custom pistons with some dome volume. You could also get the chambers welded of course, but be sure to have have a professional do the work. Would be best to get them welded/smoothed/matched and the head ported and flowed all by the same tech, if you go that route.

Call up some piston manufactures that offer custom pistons. You can take a casting of your chamber shape with some plaster and send it off so they can design a proper dome with your desired volume. Not as expensive as you would think, call some up and get some qoutes.

[deviousKA]

Also I forgot to mention, there are 2 different types of the z20 rod.

z20e 200sx should be 152mmz20s truck should be ~149.5mm

A rod length of 150mm with an 86mm l/z20 crankshaft in a medium deck height block will bring a 34mm tall ka24 piston to exact top deck. The z20e rods, if you can locate the proper set, will give you 1-2mm above the deck surface for some added compression. The edge of the piston may need to be slightly modified on a lathe to clear any protruding parts of the chamber or the headgasket (depending on bore, and spacing). The nissan headgasket thickness is .042-.047" crushed.

I dont use the stock nissan/datsun rods much, I think I have an extra set of z20s ones kicking around but sold the only set of long z20e's I had.

[TrueSlide]

I may may just use the 149.5mm rods with some custom pistons. Getting on the lathe sounds pretty technical. Not up for all that work. Customs pistons sound the safer route.

When you talk of getting them welded/smoothed/matched. You mean the actual piston? Is that safe? A machinest should be able to do that fairly cheap I would image? But how much would I want actually welded? My route I was planning was going to be z22 block with the 149 rods from z20 and z20 crank and KA pistons(cheap). Hopefully aftermarket will be cheap also.

Goal is a 8k or more revving engine that can produce in the 250 range? Realistic goals or no...?

Sorry if I sound repetative, Iam just making sure Iam getting it down and understanding. This recent surge in the KA happened sudden and is very new to me, not them datsun guys though, they hold out

I gotta think you guys for all the help though, in the end I will be able to have a badass KA with pics and vids!!

[PandaS14]

what devious is talking about is welding material into the dome in the combustion chamber. The head. By doing this, you can increase detonation resistance, while increasing compression. Seems like those two don't come hand in hand, but when done right, they do. You then shape the metal you welded into the head down to a desired shape and finish.

[TrueSlide]

A weird thought came to me today. Is it possible to use the KA24E top end and harness/ECU and the a frankensteined bottom(z22 block/z20 crank/rods, etc. etc.) I know the oilpressure sensor is on the ka24e, the only sensor close to the block, but it seems like with a tad work it can be rerouted and worked. Since have that bottom in combo with KA pistons and head, devious said it would yield a "relatively" low. Great for a turbo application? Hopefully not too low. Maybe some mazda pistons could be reworked and yeild slightly higher maybe stock 240 compression.

I guess what Iam thinking is, with a turbo the KA maybe able to produce good power at a decent RPM. And you have the fully counter weighted crank(with some machine work)

?????

[SonyPete]

Quote »what devious is talking about is welding material into the dome in the combustion chamber. The head. By doing this, you can increase detonation resistance, while increasing compression. Seems like those two don't come hand in hand, but when done right, they do. You then shape the metal you welded into the head down to a desired shape and finish. [/quote]Well your leaving out the most important part and that is welding up the combustion chamber around the edges and bringing it all the way to the flat of the head. This creates a bigger quench area. But you have to weld and shape it so your squishing out air towards the spark plug not away. So you would only weld up the opposite side of the spark plug or the two sides around it aiming the fuel charge towards the spark plug. You don't just randmonly add material to the inside of the combustion chamber only at the edges.