ARP Hardware NAPZ 2.4

[datzenmike]

I forgot the crank. Again the Z24 was built for highway speeds with not much thought to high revving performance or increases in it so the crankshaft was not fully counter weighted like the smooth revving L20B.

[Stoffregen Motorsports]

Also, the pistons are not so great. For use with a turbo, the compression may need to be lowered, which means either cutting the pistons or getting new ones. Cutting them will make them fragile, so that option probably isn't for you. Another aspect of the pistons that is less than ideal is the archaic ring pack. Modern rings are far better.

 

You may be able to use a KA24DE dished piston to help lower the compression, though I have not actually done the math to see if they will fit. As a bonus, the KA24 rings are modern, low tension rings.

[datzenmike]

The Z24 pistons have a 15cc dish and the compression is relatively low at 8.4.

[Stoffregen Motorsports]

I know next to nothing about the stock Z24. Robbed plenty of cranks from them, but only built one or two.

 

8.4:1 is good for a low boost turbo. I wonder how the stock pistons would hold up. Probably be ok for a couple pounds, maybe five. The KA24 pistons were a hypereutectic piston and as I mentioned earlier, the ring pack is superior to the Z24.

[datzenmike]

here many factory engines with hypereutectic pistons and a really good head gasket. Dodge Daytona 2.2, Ford 2.3,  280zx, CA18ET. As long as boost is 6-7 PSI. You can run quickly to 10 but boost being boost and boys will be boys too much of a good thing and the piston is holed.

[Madkaw]

On 2/1/2021 at 5:54 PM, datzenmike said:

here many factory engines with hypereutectic pistons and a really good head gasket. Dodge Daytona 2.2, Ford 2.3,  280zx, CA18ET. As long as boost is 6-7 PSI. You can run quickly to 10 but boost being boost and boys will be boys too much of a good thing and the piston is holed.

Not sure if you know or heard of Patrick Smith , but he swears one of the reason for HG failures with these engines is the crude finish on the block mating surface. Scratches that cause HG failure . 

 

[datzenmike]

How is Patrick???

 

 Somehow the head bolts loose their clamping pressure over tens of thousands of heat cycles. The gasket de-laminates. The preventative is to re-torque them once a year. I've heard it's the metal used in the block. The Z24 is 2cm taller than the previous Z22 and it's all under the deck. I know the threads start about 1/4" down from the top surface. I don't know how or if this affects it. 

[bottomwatcher]

On 1/30/2021 at 2:43 PM, Stoffregen Motorsports said:

Just motor mounts to get it in the truck. Plumbing and exhaust, intake, throttle cable, some wiring, done.

Yep that's all. Actually I have a 4x4 so the custom oil pan plus routing exhaust the cam am box nothing too it! Actually took me nearly two weeks full time to figure every thing out. Custom rad hoses pie cut weld exhaust then weld again. Wiring holy crap! But hell a kae powered 720 is a dream to drive. No more middle finger solutes on an incline. Not a rocket but I feel like I am in a 1995 not an 1982 vehicle. Just yanking your chain Stoffy this is a worthwhile swap but it ain't that easy if you don't have a full shop and a lift. Curios about how you make 250 hp? 

Redneck shop!

[Stoffregen Motorsports]

Well I suppose it's still a lot easier than another type of swap.

 

I have built dozens of KA24E GT3 race engines, and a few KA24Es with dual side drafts for street cars, but only one street KA24E with EFI. Back then there wasn't a lot of demand for EFI performance. It was so long ago, but I do remember that the motor was mildly modded and it made 250hp. One mod I clearly remember was having Jim Wolf install a removable chip and do the tune on the stock ECU.

 

Cool garage.