Napsz z20,z22,z24 differences and similarities.

[Thisolddatsun]

I have many ideas and curiosities about the Napsz and I know that the main difference between the 3 is the internals. Everything outside is pretty much interchangeable between the 3 motors. What my question is are the intakes different between the engines? I noticed the weber adapter plates are different between z22 and z24 intake. The z22 uses a 2piece adapter whereas the z24 uses a one piece. Would there be any gains/loss swapping a z24 intake onto a z20 or z22? Or vise versa? And I have heard z24s are complete garbage compared to a z20/z22 because they blow headgaskets every 100k miles and are prone to cracking or is it a napsz engine thing? I know retorquing the head bolts every so often when its cold can prevent that. But also in the same sense would boreing out a z20 and using oversized pistons and putting a worked z22 head (cam port polish etc) have any gains?

Depending on the bore. Iv been looking around online for months and cant find anything.

[ol'rusty1980]

the head gasket thing is probably due to people over heating them

[ol'rusty1980]

looks like they are all aluminum and they all three are deffinately differnt

[ol'rusty1980]

so id say that the cylinder head are different between the z20 z22 and z24

[Fat510]

Get a z22 block bored to 89mm and get some ka24E pistons. Z24 pistons have a bigger dish than ka24e pistons and will drop the compression

 

You can use either the z22 or the larger port z24 heads.

[datzenmike]

Z20 is basically an L20B with a different head on it. The '80-'82 S110 200sx uses the same head as the Z22 and they have EFI injector ports and flattop pistons. The combustion chambers are 57cc. The Z20 from the A10 (later 510) and the 720 Mileage option engine uses a slightly smaller combustion chamber around 45cc but with dished pistons on the A10 and flattop pistons on the 720 truck for a 9 to one compression.

 

Z20 and Z22 heads have round intake ports, intakes are the same, same cam and valves. Z20 and Z22 cranks can be interchanged. Most Z22s use L20B rods .

 

Z24 engines have even larger dish pistons to keep the compression around 8.4 . The rods are even longer and the crank longer still. The Z24 crank will not fit into the Z20/22 block without trimming. Z24 heads are 57cc and have square intake ports with rounded corners. Cam and valves are the same as Z20/22.

[Thisolddatsun]

Z20 is basically an L20B with a different head on it. The '80-'82 S110 200sx uses the same head as the Z22 and they have EFI injector ports and flattop pistons. The combustion chambers are 57cc. The Z20 from the A10 (later 510) and the 720 Mileage option engine uses a slightly smaller combustion chamber around 45cc but with dished pistons on the A10 and flattop pistons on the 720 truck for a 9 to one compression.

 

Z20 and Z22 heads have round intake ports, intakes are the same, same cam and valves but the Z22 rods are longer for the longer stroke cranks. Z20 and Z22 cranks can be interchanged. Most Z22s use L20B rods .

 

Z24 engines have even larger dish pistons to keep the compression around 8.4 . The rods are even longer and the crank longer still. The Z24 crank will not fit into the Z20/22 block without trimming. Z24 heads are 57cc and have square intake ports with rounded corners. Cam and valves are the same as Z20/22.

Could you do a z22 crank in a z20 block with 89mm ka24e pistons with z24 rods since they are longer or does that require a z24 crank?

Could you dremal the intake ports to be round on a z24 intake or would it just br easier to do a z24 head?

[Lockleaf]

What's the goal you are shooting for? Long stroke, high compression, high rpm, big on torque, just a custom different engine because you can? There are definitely a variety of ways these can be built, but knowing what you are looking for might help some of the local engine experts get you there.

[Thisolddatsun]

High compression and lots of torque mainly are what im looking for.

[datzenmike]

Could you do a z22 crank in a z20 block with 89mm ka24e pistons with z24 rods since they are longer or does that require a z24 crank?

Could you dremal the intake ports to be round on a z24 intake or would it just br easier to do a z24 head?

 

If boring to 89mm why do this on an 86mm bore Z20 block? Why not bore it on an 87mm Z22 block? Either will work, but less to remove on the Z22 block. Just fit KA24E pistons onto the Z22 rods onto the Z22 crank (note that the Z22 had two different rod lengths, you want the 145.9mm length identical to the L20B rods)  I forget the compression when used with an open chamber L head. I ma doing something similar but have decked the block 1 mm for needed compression increase.

[Thisolddatsun]

If boring to 89mm why do this on an 86mm bore Z20 block? Why not bore it on an 87mm Z22 block? Either will work, but less to remove on the Z22 block. Just fit KA24E pistons onto the Z22 rods onto the Z22 crank (note that the Z22 had two different rod lengths, you want the 145.9mm length identical to the L20B rods) I forget the compression when used with an open chamber L head. I ma doing something similar but have decked the block 1 mm for needed compression increase.

I have both a z20 and z22 in my back yard that need to be rebuilt along with a z20 in my 720. How hard is it to fit 89mm ka pistons onto the z22 rods? And i really dont know the condition of the motors besides the fact that the z22 is sized and the z20 blew a bearing. When i pulled them i just left them outside in the elements. Been 1 year almost 2 years they've been outside. As for the pistons what would be better to use? Forged, cast, flatop, dished? Can you even get 89mm ka pistons in different sizes?

[datzenmike]

KA24E car (240sx) pistons are fully floating on the rods. I sized my Z22/L20B rod small ends to accept them. It's a small HP increase from a small friction reduction. Truck KA pistons are press fit on the piston pins. The floating pistons can just simply be pressed onto the L20B or Z22 rods and just forget about floating them. Either way will work.

 

If the Z20 had a bearing failure the crank is likely bad too. The 152.5 mm rods are way too long for use on a Z22 crank so forget them.

 

 

I have both a z20 and z22 in my back yard that need to be rebuilt along with a z20 in my 720. How hard is it to fit 89mm ka pistons onto the z22 rods? And i really dont know the condition of the motors besides the fact that the z22 is sized and the z20 blew a bearing. When i pulled them i just left them outside in the elements. Been 1 year almost 2 years they've been outside. As for the pistons what would be better to use? Forged, cast, flatop, dished? Can you even get 89mm ka pistons in different sizes?

 

Seized? if just frozen from getting rusty, this is no big deal. If seized like a spun bearing then you are screwed. You will need a new Z22 crank and rods to complete this build.

 

As the Z22 block has to have a major bore increase it won't matter how rusty the cylinders are. Hopefully the crank journals are capped and stayed rust free. Measure the Z22 rods they must be 145.9mm center to center of the large end to the pin end or just get a set of L20B rods, they are the same. This is what I am doing. Got a block (crank was totaled) Had a spare Z22 crank and lots of L20B rods laying around. KA24E pistons from an '89 240sx. Bored the block to 89mm and that is about where I am now.

 

A Z22 bore to 89mm with Z22/L20B 145.9mm rods on a Z22 crank makes a 2288cc (2.3 liter) big bore engine. If you run a U67 L20B open chamber head your compression will be 9.787.  A closed chamber head would be 10.39 but the closed chamber heads won't breath as well as the U67 and this has an extra 300cc above that of the L20B.  So...

 

The KA piston is shorter than the Z22 piston and does not come to the top of the cylinder at TDC. There is just over 1.5mm so if you were to mill (or deck) the block 1mm which is what I have done your compression will jump to 10.71 with an open chamber head. 

 

About high compression... It often hard to live with. While it makes the combustion process more efficient it's often with annoying pinging, high octane gas, not that much power increase unless the engine is fully modified. If you make 120 hp, and a 2.3 should easily make this, every point of compression increase output about 3%-5% but this becomes less as the compression get maxed out. Conservatively 3% times 8.5 increase to 10.71 (about 3 points) gives you about 130 hp. Keep in mind this isn't 130 useable hp but 130 at max PRMs, about 6.5K. It makes much much less just driving around. The 2.3 that I am building will run about 8.9 an that's fine for me. 

[Thisolddatsun]

I sized the z22 and pulled it out ran it out of oil and didnt realize till it was to late. It sized up on the way to get oil. And I would also like the engine to have a long life. So if the cranks dead doesnt that mean I have to get one along with a z22 rebuild kit minus the piston heads? And what is a u67 open chamber head? I would love to do a l20b head on it but from what I'v read and been told its way harder to do in a 720. I guess a reasonable amount of compression I dont think I really want to premium in it. Id just like to have a little more power without a huge engine swap like a v6. Its alot easier to put a stock engine in.

[That4doorKiD]

Don't use a Nap-z head if your going for a build. Go with an L-series head L20-B. The Nap-z were made for California smog regulations, therefore having less performance, whereas using the l20b head breathes better and goooder performance. You should research stroker builds, raise the compression on your motor with head and pistons, + high octanew fuel = would be awesome.

 

http://community.ratsun.net/topic/59269-z24-interchangeable-heads/?hl=lz24&do=findComment&comment=1030996

[datzenmike]

I sized the z22 and pulled it out ran it out of oil and didnt realize till it was to late. It sized up on the way to get oil. And I would also like the engine to have a long life. So if the cranks dead doesnt that mean I have to get one along with a z22 rebuild kit minus the piston heads?

Yup, said it right here...

 

 

Seized? if just frozen from getting rusty, this is no big deal. If seized like a spun bearing then you are screwed. You will need a new Z22 crank and rods to complete this build.

 

 

Yeah that's a lot of work. Why not swap a KA24E or DE in? It fits your transmission and makes areound 150 hp stock.

[Thisolddatsun]

Yup, said it right here...

 

 

 

 

 

Yeah that's a lot of work. Why not swap a KA24E or DE in? It fits your transmission and makes areound 150 hp stock.

Dont really want to do a big engine swap enless Im going to do a v6 and I'm still debating on fuel injection or not. In a sense swapping a ka24e in is around as much work as swapping a l head on right? Really was just wondering what the build possibilities are for the napsz using the z head. Mine is 4x4 and with a swap oil pan clearance comes into play as well. Iv been thinking about doing the front brake upgrade with a 86 4x4 and moving the differential so i can use the 86 cv axles. If I used a v6 truck and or pathfinder for the front end and mounted the diff in the same place a v6 swap wouldn't be far behind just because I wouldnt have to modify the oil pan to clear the diff.

[Lockleaf]

The only advantage the L head has is above 4500rpm. If you street drive laid back style, then you won't really ever break that, so who cares if the L flows better at 6000rpm? I never really take my z24 720 above that rpm. No real reason to.

 

For what you describe, at most reasonable cost, using all the good parts you already have, follow Mike's advice. Z22 punched out to run 240sx pistons etc.

 

Have your crank and rods checked by a machine shop to see if they are salvageable (unless you know you did them in, I blued and magnetized a rod once I did so much damage to it :-) ). It's usually free it just a couple bucks to get stuff inspected. If not, post a want ad here for the parts you need and/or hunt junkyards. By the time you pay for those parts new/reman you may as well buy a ka24 and pay someone to combine the pans together to fit both engine and diff, and go that route.

[datzenmike]

The L head swap also means you need the two manifolds for it also. As the L series leans to the right to have room for the manifolds on the drivers side, you will need a correctly leaning L series oil pan and engine brackets.... now the Z series transmission will not line up and you will need to swap an L series front case onto it. Gets complicated.

 

Running KA pistons on a Z22 block won't work so well if you keep your Z head. You are gaining only 100cc of displacement and the compression remains at 8.4.

 

 

It's all academic at the moment as both your cranks are toast and at least one each of both rod sets.

[Thisolddatsun]

Thats why i figured the l head swapnwas out of the picture. I mean anything can be done its just the amount of money. Thats why I was wondering what I can do with a z head. Even if its not much id rather spend 1k rebuilding a engine than ordering a 900 remanufactured engine.

[Thisolddatsun]

The L head swap also means you need the two manifolds for it also. As the L series leans to the right to have room for the manifolds on the drivers side, you will need a correctly leaning L series oil pan and engine brackets.... now the Z series transmission will not line up and you will need to swap an L series front case onto it. Gets complicated.

 

Running KA pistons on a Z22 block won't work so well if you keep your Z head. You are gaining only 100cc of displacement and the compression remains at 8.4.

 

 

It's all academic at the moment as both your cranks are toast and at least one each of both rod sets.

Hey mike just a hypothetical question...

but diesel engines in General have a high Compression ratio and high ammounts of torque at low rpms. Gas engines are the opposite but more of a broader spectrum of rpms. The z heads are good turbo canidates for the cross flow (i think i forgot) and run out of breath around 4,500/5,000rpms. So hypothetically speaking could you set a z20/z22 with a higher compression and a turbo and produce a good ammount of low end torque?

[datzenmike]

Diesel and gas engines are vastly different and just because a diesel has 22 to one compression and lots of torque doesn't mean a high compression gas engine will too. Diesels tend to have a very large stroke so lots of leverage.

 

It might if it's getting any boost at low speed. Turbos tend to make boost when revved up.

[Thisolddatsun]

Diesel and gas engines are vastly different and just because a diesel has 22 to one compression and lots of torque doesn't mean a high compression gas engine will too. Diesels tend to have a very large stroke so lots of leverage.

 

It might if it's getting any boost at low speed. Turbos tend to make boost when revved up.

So if its making boost at low rpms it is possible? Would it be better to keep the compression lower for low rpm torque?

[datzenmike]

I wouldn't raise the compression above stock unless running an inter cooler, oil cooler, fresh air intake, some form of boost related ignition retard and water alcohol injection to control detonation. Air temperatures have to be kept as low as possible .

[Thisolddatsun]

I wouldn't raise the compression above stock unless running an inter cooler, oil cooler, fresh air intake, some form of boost related ignition retard and water alcohol injection to control detonation. Air temperatures have to be kept as low as possible .

fresh air intake. Would that be like a snorkel or cold air intake? And water alchohol injection what is that