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Noob LZ23


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11 hours ago, datzenmike said:

The KA24E was only used in the '89-'90 S13 240sx not the S14 and had floating piston pins. The truck used the same pistons but were press in pins. Where are you getting the dish and dome numbers? I see -11.5cc and assume this is a dish volume???


$600 for forged pistons???? way to much unless boosting.


An LZ23 with an 11.5cc dish and open chamber L head would make for an 8.75 compression..... not to bad.


An LZ23 with an 10.4cc dome and open chamber L head would make for a 12.02  compression..... not good.



Substitute Z24 pistons with 15cc dish for 8.4 compression. You can deck the block 0.5mm for 8.7:1 compression or 1mm for 9:1 compression. You could also mill the head slightly.

The pistons don't care which rod they use, so you can use a piston originally designed for a floating pin with a pressed pin rod. It's the rod that gets machined to allow floating. All pistons have bores machined for the pins to float inside them.



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12 hours ago, Jitenshakun said:

I've been doing more looking and stock KA24e pistons aren't an easy option anymore. That said, what about Arias?  The 2 options are a dish and a dome. - 11.5cc vs. 10.4cc. Which one is the way to go?



Have you tried sourcing your parts from a local machine shop? They have access to more parts than the average person even knows exist. I'd be surprised if they can't source a set of aftermarket replacement KA24E pistons for you.


Neither of those Arias pistons are ideal. If you want custom pistons, call up a piston manufacturer and order a custom set. Wiseco, JE, Arias, Cosworth - they all have experience with Datsun/Nissan and if you tell them what you're building, they will have a design ready to go.

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The gasket needs to match the bore. So if you've got an 89mm bore, you need to use a Z24 gasket. Just snip the corners off where the timing cover meets the head and fit them into the spots where they need to go. Use black or grey RTV to help hold them and seal up the gaps.


Also, lay theold gasket over the new gasket to see if any coolant passages need to be opened up. There is a coolant pasage at the back of the gasket that sometimes does not appear on the Z gaskets, and a hole punch can create that hole.


A race prepped 210 head? Race prepped for what? ITC? That's a small valve head and not good for much. Or to put it another way, it would take a ton of work to get that head to be as good as even a stock A87 head. Are you sure it's not a 219 head?

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I used a Z24 head gasket on my LZ24 and it will fit the L series timing cover, just. There is a 'close spot' on the corner below the fuel pump. I just built it up with JB weld. The Z24 gasket holes do not match the L series 10 mm bolts on either side so a thin smear on both sides and the front of the gasket will seal in the oil spray and fumes.





Z engines do not have this passage up into the head so the Z head gaskets are straight across just barely touching the hole so I built it up with JB.huoHJWz.jpg


T0 make functional, you have to bring water over from this other coolant passage yhat does come up from the blockby grinding a small trough.





Yes the 210 head is undesirable. Rumor is that the 210 was originally designed for the L14 but ended up on the L16. Don't forget it was used on a 1.6 liter engine and you are asking it to flow 2.3 liters through it. More than 43% more air!!!  Look for a U67 head with 42mm and 35mm valves. The intake port is 1.375" vs. the 1.125" on the 210 head. Compression on an un-cut U67 would be 8.75 but don't get excited over larger compression numbers. It's only worth a lot on a highly modified engine. The increase in flow using a U67 will more than make up for the compression.

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I'm in a tricky spot between local guys without L-head experience and an A87 core and a finished 210 by a very experienced race engine builder. The 510 guys figure a 210 has as much potential, but it boils down to who is doing the work. 


I'm trusting the builder here and at absolute worst I'm swapping heads sometime down the road. 

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The 210 head you have is not really a "210" anymore.  With those larger valves and seats and port work, in conjunction with the smaller chamber to give a higher compression ratio, it could work fine.  You should verify end compression calculations though.


Interested in the A87 if you don't think you will use it. 

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Just now, iceman510 said:

I also have a Z22 oil pan from a '71 720 2wd if that would be any use to you.


I have that pan, a L20 2wd pan, and my Z24 4x4 pan. As I'll be running L20 engine mounts I foresee a modified pan in my future. 


My A87 is untouched so a good core. I may sit on it a bit as a backup. 


Good call on the compression numbers. I ran my spreadsheet a few times. 


572cc + (9.63cc + 7.46cc + 11.5cc + 38.5cc) = 639.09 /67.09 = 9.53

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1 hour ago, Jitenshakun said:

The 510 guys figure a 210 has as much potential, but it boils down to who is doing the work. 



I wouldn't say it has potential but I would say it has much potential for improvement because it is so far down that anything you do will be an improvement. You can't hog the ports out to U67 size without risking hitting the water jacket. Replacing the small valves with larger ones is a must.

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2 hours ago, Stoffregen Motorsports said:

Right, the ports are very small and opening them up that much is dangerous. But, if it's already done and works well, go for it.

This is the risk of having a race engine builder do the work. They will go right up to the limit and then nudge it a little. 


I have many off ramps in this project and will be ok adapting. Bottom end work might be done by a land speed record guy, so that'll be fun too. 

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