Z20 NAPZ vs. L20?

[metalmonkey47]

What are the main differences between the two?

 

I just got home with one, identified it as a Z20E, And I'm curious. The timing cover looks like one that Skib identified on another thread as the L20 timing cover.

[datsunaholic]

Well, the main differences are the timing cover, timing chain, head, rods, and pistons.

 

The block itself (and the crank) are essentially the same starting in late '79, though there's some minor differences in machining. Such as where they put the serial number.

 

But without a photo, we can't tell.

[metalmonkey47]

Oics coming shortly. It's in pieces, so what all do you want?

[HRH]

Ah hah! There are two very big differences between car and truck Z20s. If you got the car (EFI) motor, it will have flattop pistons with the longest rod combination for the L20B block. That's what I have in my motor. The truck got the regular rods with a dished piston similar to the L20B. As datsunaholic said, most everything else is the same. Yank the head off to find out what pistons, or try to peer down the spark plug hole.

 

The L timing cover and everything else can be used on the Z block. The main difference is the oil port in the block is moved slightly, so if you use an L head on a Z block, you need to chamfer out the head hole so it gets oil up top. Not much, maybe 2 or 3 mm off.

[metalmonkey47]

It IS the EFI motor with flat top pistons so I guess that's a good thing

 

I'll get oics up in a little bit, so you guys see what I'm working with.

 

 

 

Am I gonna have to go the same route for building an L20 out of it as if it was a Z22?

[HRH]

Yes, that is a good thing! You can make a raped ape motor out of that no problem. You'll actually have an easier time out of this than an L22. You can use the stock L20B head gasket and the 20B head and cover. The only thing you'll need to do is chamfer the oil port on the L head you're planning on using. I suggest a milled U67 or an unmilled close chambered head. If you're going for massive flow, use the U67 or U60 (same thing) head, but beware of detonation. Peanut head will have less detonation potential but will also be very high compression due to the flattops and much smaller cc compression area. You can back off the timing quite a bit and use a mild cam to make it streetable with excellent torque.

 

Make sure you at least replace the rod bolts if you're going to be doing this. Reusing the pistons if they're okay isn't a problem, but definitely new bearings, new rings, new rod bolts at the very least. Nissan OEM or ARP bolts are a good idea. Depends on if this is a budget build or an expensive build. The head stud kit is also very nice. I have that on the 510. It's a little overkill on my motor, but it's worth it if I ever raise the compression more, and it seals better over the long term.

[Z-train]

If you can find a Z-22,then you're 2/3s the way to a LZ-23 stroker.

[HRH]

True, but the only thing you miss out on with the long rod Z20B combo is the extra crank stroke. I wanted to do the same thing, but this is the next best option short of going out and sourcing a Z22 in good condition.

[metalmonkey47]

Heres the pics

 

I'm building it all on a budget, but I'm not afraid to spend money where I have to. I'd love to build a low boost F/I in the furture, but who knows.

 

I'll be looking for the L head soon

 

 

I've already de-greased the block, sanded it down, and painted it. I like it

 

[metalmonkey47]

Oh and I even got my GF working on it :rofl:

 

 

[HRH]

Do you have a closer picture of those pistons? I'm thinking those are the truck pistons, looks like they have a good dish to them. The car pistons should be literally flat tops with very very tiny valve reliefs. Less than 2 or 3mm deep. Which means you won't have the long rods, so essentially it's L20B compression ratio. That means the peanut head is more desirable. Or cut .060 off the 20B head, just be prepared for being more detonation prone if using an open chamber head.

[datsunaholic]

Unfortunately the pics don't show the part we need to see on the timing cover. We need to see the top. The lower halves look the same.

 

the valve cover is a Z24 one though.

[metalmonkey47]

Do you have a closer picture of those pistons? I'm thinking those are the truck pistons, looks like they have a good dish to them. The car pistons should be literally flat tops with very very tiny valve reliefs. Less and 2 or 3mm deep.

Not at the moment, I'll get one tomorrow, but it's DEFINITELY flat top. The picture makes the valve relief's look a little deeper, but I'll take one out tomorrow after work when I hone the cylinders and get you a better picture.

 

Unfortunately the pics don't show the part we need to see on the timing cover. We need to see the top. The lower halves look the same.

 

the valve cover is a Z24 one though.

 

I thought it seemed a little wide. I know it was on the engine though. The guy said when he bought his 210 it was already Z20 swapped, so maybe theres some weird mod? I gotta go pick up the head tomorrow, so I don't have it right now.

 

 

Is this picture any better? I got it from my cell earlier in the day.

 

 

 

[ggzilla]

The Z-series engine was designed to be the replacement for the L-series in the 2.0 to 2.4 liter category. It is based on the L-series design and shares many parts.

 

Major differences are:

* Crossflow cylinder head (both L and Z are SOHC designs)

* Z-series is not installed on a slant like the L-series slant 4s so the tranmissions differ slightly

 

Z-series was replaced by the KA-series. KA makes more power with the same CCs e.g. Z24 vs KA24.

* Z24 SOHC - 106 HP

* KA24 SOHC - 140 HP

 

Compare to L-series

* L20B - 110 HP single carburetor

* Z20S - 88 HP single carburetor (105/110 HP JDM)

* Z20E - 100HP EFI USA

[datsunaholic]

Well, I think that's a Z20 timing cover by what I can see. The top surface would be more telling (NAPS-Z have 3 bolt holes, L-series have 2) but I think the casting number IDs it too. Plus the distributor drive flange is right for a NAPS-Z.

[HRH]

Yeah, definitely a Z20 timing cover. Angled top face, dist. plate, and two bolt holes, but not another half inch on top of the two bolt holes, so not Z24.

 

Oh, and ggzilla, KA24E sohc hp was 134. Poor gutless stock things. (I'm splitting hairs here, but for the sake of typing on ratsun. ;) )

 

I'm still thinking you have the truck Z20 based on those pistons. Measure the connecting rods to find out. They will be the longest rods available in the 20B/Z block. I think a 1/4" longer than the regular 20b rods. Maybe 6" iirc?

[datzenmike]

It's a Z20S block and pistons. Probably swapped to replace a blown Z20E motor. Thing is the flattop pistons are mated with a larger Z head on the Z20E. The Z20S used a smaller combustion chamber head to offset those dished pistons.

 

Matt the truck Z20 motor also used the flattops and long rods but also the smaller cc head from the car Z20S (A10) to achieve a 9 to 1 compression.

 

Z20E piston from 200sx

 

Z20S piston from A10

 

The Z20E, Z22 truck and Z24 heads are 57cc

The Z20S from the A10 and the Z20 used in the 720 are about 45cc.

[datzenmike]

Metalmonkey... definitely post a picture of the combustion chamber. If I'm right the combustion chambers are small and have small flat spots to the intake and exhaust sides. Like this:

 

 

Here's a Z22 I was working on. Note the combustion chamber is perfectly round.

.

[Charlie69]

Mike I have always considered the combustion chambers as you pictured (round) as hemisperical (hemi) combustion chambers. Am I wrong?

[datzenmike]

I like to call them HEMI... they aren't, strictly speaking the valve angles are wrong. But it's very close, dual plug too FTMFW

[ninja philbo]

god i want a z efi manifold does anyone kno if a ca20e intake or ka24e intake would fit ??

[datzenmike]

The Z series EFI, KA and CA efi intakes only fit those motors.

[HRH]

It's a Z20S block and pistons. Probably swapped to replace a blown Z20E motor. Thing is the flattop pistons are mated with a larger Z head on the Z20E. The Z20S used a smaller combustion chamber head to offset those dished pistons.

 

Matt the truck Z20 motor also used the flattops and long rods but also the smaller cc head from the car Z20S (A10) to achieve a 9 to 1 compression.

 

Z20E piston from 200sx

 

Z20S piston from A10

 

The Z20E, Z22 truck and Z24 heads are 57cc

The Z20S from the A10 and the Z20 used in the 720 are about 45cc.

 

The Z20 car piston (top) you show is what I used in my 20B. The bottom one definitely is not a flattop. I've only found that bottom variety in truck motors, not to say there aren't other versions. I've just never seen them down here. Then again, I've only had my hands on a few truck Z20 motors. Metalmonkey's pistons look like the bottom picture though, which would be not flattops, and would yield low compression with anything other than a peanut head or severely decked 20B head. Also, the pin height is lower, so as to use the 20B rods. Not the long rod Z20 application.

[Z-train]

Sorted related:I know there was a JDM L-20B FI manifold,but what about a L-16 or L-18 FI manifold.And if anyone should need a Z-22 head,i have one.

[metalmonkey47]

Okay, you guys were right, they are dished. I never got a good look before, but they are definitly dished.

 

I'll still measure the rods and post oics of internals, but I'm sure it's not the long rod. More info coming up in a few hours.

 

 

god i want a z efi manifold does anyone kno if a ca20e intake or ka24e intake would fit ??

 

I may be selling all the Z20E EFI stuff soon. If you're interested I'll PM you when I decide.

Edited April 19, 2011 by metalmonkey47