Z24 Heads

[LTM]

I don't know much about Z24 type heads and would like to learn. My question is the difference between a W04 head and a 10W head. How would the difference if any have an effect on the engine. I have a 10W head.

[datzenmike]

The W04 head is from an '84-'86.5 Z20 Mileage option 720 engine. It has smaller designed combustion chamber volume that are 85mm diameter across and combined with the Z20s flattop pistons produces a 9 to 1 compression. Wo4 and 10W heads use the same cam and valves.

 

The Mileage option Z20 has a knock sensor in the block and an electronics package to retard the ignition timing in response to detonation. The W04 head has round intake ports. Used on a much larger displacement Z24, even with the 15cc dished pistons, will result in a 9.5 compression and you should use a Z24 head gasket.

 

Round Z20 and Z22 intake port top and Z24 'square' intake ports bottom.

 

 

 

The W04 combustion chamber is flattened slightly on each manifold side providing a small quench area.

 

The 10W is a Z24/Z24i specific head with a larger volume, 89mm diameter round combustion chamber. It has square intake ports with rounded corners. The compression is about 8.25 to 1.

 

 

 

 

 

To further address how a W04 head on a Z24 would affect it. Increasing the compression will increase engine efficiency as long as you don't exceed the gasoline's self ignition point. (pinging) Increasing the compression to 9.5 would probably induce some detonation or pinging on regular octane gasoline. Moving to a middle or higher octane might help. The increased efficiency (MPG) might outweigh the added cost of the fuel. Or you may just turn the timing back slightly to reduce it. Increased compression will increase the heat around the spark plugs increasing the chance of a pre-ignition 'hot spot' and you may have to put in a colder set of plugs. Stock are BPR6ES for intake and BPR5ES for the exhaust. You may be able to get buy running colder BPR5ES exhaust plugs in the intake side as well. Popular wisdom says that for every point of compression increase you can (sort of) expect (maybe) a 5% increase in power. (on a good day) So if the Z24 makes 105 HP it might make 110 after. (I'm being conservative here so feelings are not hurt because of too high expectations) Keep in mind this is not 5HP at all speeds only when revved out. It's (maybe) 5%.

 

For example I have it that the Z24 makes 130 torque at 2,800 RPM. This computes to 69.3 HP so + 5% is 72.7 HP so I doubt you will notice this.

[LTM]

Good information, thanks. Whats your take on the exhaust port?The exhaust port on the10W is more rectangle with rounded corners and the W04 has more of a round port.

[datzenmike]

I don't have a W04 head but I have 2 Z20E (EFI) two Z22S 720 and two Z24 heads and all squarish with very rounded corners.

 

By part numbers the Z20/22/24 share the same exhaust manifold.  Can you post a few pictures of the Z20 W04 head? and the exhaust ports??

[LTM]

The top head is the 10W and W04 intake port

The second photo W04oto top is W04 (gasket on both W04 and 10W left ex. port)

[datzenmike]

Looks like exhaust W04 on top of the 10W and the second picture is the same. The Z24 exhaust look larger but it may be the carbon footprint... and squarish to me.

[LTM]

Sorry, I sent two of the same photo. Would the W04 affect performance with smaller ex. ports?

This a photo of the intake ports. W04 on the bottom.04 on the bottom.

[datzenmike]

Not convinced that the W04 exhaust ports are smaller. Measure them.

 

My bad. I assumed the W04 being a Z20 would have the smaller round intakes.

 

Thank you so much for the pictures.

[LTM]

I will measure the ex port. I placed the ex gasket on the left W04 and 10W ex port for comparison and the right side without the ex. gasket.

[Logical1]

I pulled this head off a Z22 as the owner only wanted the block for a LZ build. How does it compare? 

 

 

[LTM]

Not sure but it looks more like the 10W head ex. port.

[datzenmike]

This is a Z20E or Z22E head from an S110.

[LTM]

I measured the port on W04 head the best I could and it is smaller and rounder. The head will bolt up to my engine, I would like to know if is it OK or not to use the W04 head.

[datzenmike]

Yes will fit and work, but note what I said about the increased compression ratio and what problems it may cause and what to do about it.

[LTM]

Thanks Mike It's a load off my mind.

[datzenmike]

Valves and cam are the same, the exhaust ports slightly smaller but of no importance, combustion chambers are smaller, intake ports are same as Z24 (did not know this) 

[LTM]

Thank again

[Charlie69]

You all have got my couriosity up on a couple heads that I have.  MIke any way of telling what vehicles these came out of?

First came with a Z24I.  Notice the Kangaroo on this head.  The Guam racers want the kangaroo heads for building the Z24s

 

Second is on my Z20.

 

Edited March 26, 2021 by Charlie69

[datzenmike]

 

10W apparently is a Z24/Z24i head. NMCA... Nissan Motor Company Australia??? It's not a stretch to assume a kangaroo might mean it was cast in Australia.... https://en.wikipedia.org/wiki/Nissan_Motor_Australia.

 

I have two Z20E heads like yours from an '80-'81 S110 200sx. I assume the Z20E*/Z22E are the same other than casting numbers. They are different from the A10 HL510 Z20 and the truck Z22 in that they have that threaded hole beside the #1 exhaust spark plug for the engine coolant sensor, not sender for a gauge but sensor to tell the EFI how warmed up the engine is.

 

*I will say that the '80 has the sensor in the intake and in '81 it was moved to the head for a faster response and more accurate reading.

[Charlie69]

The sensor hole on my Z20 head is threaded but is not drilled (open) into the water jacket.  I looked every where for a threaded plug for that hole but was unable to determin what thread it is.  Not metric, not Americam, and not British.  I have many plugs on hand now that I bought trying to plu this hole and then I got smart and blew some compressed air into it and it just blew back out of the hole, the air did not come out anywhere else.  Yes I feel stupid!  LOL

 

In my search for the plug I came across another 84 720 2wd with the Z20 in it and there was nothing in that hole on that truck either.  This 720 was also a carbureted engine.

Edited March 27, 2021 by Charlie69

[datzenmike]

Charlie... it may not have to be into the coolant and only have to sense the heat in the metal. It's for the EFI to help know when the engine is warm enough to shut some of the start up fueling off and set leaner. It's not the same as the engine gauge for the dash which does read coolant temperature. Again I assumed.... that it was into the coolant. Perhaps not.

 

 

[Charlie69]

You are most likely correct in it sensing head temp as apposed to coolant temp.  Is there a part # for this sensor.  I want to set a Z24 up on multi-port injection.

[datzenmike]

A guy named Patric Smith in Vegas has a Z24 with Z20/22E intake and KA sensors ECU injectors etc.

 

Temperature sensors....

Z20E and Z22E are 22630-P8100

 

S13 KA24E is 22630-N4200

S13/14 KA24DE is 22630-51E00

[Charlie69]

Thank you Mike these are still available at the Nissan parts.

[KELMO]

Patrick Smith is usually at the Williams show and usually brings a 720....or 2.