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L20b Pistons


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I'm needing a set of Pistons for an L20b that needs boring out, amongst a heap of other stuff. I'm not sure on year of engine, but it has square exhaust ports, and it came from Australia apparently. I'm ordering a load of parts from Rock Auto but they seem to have limited stock on earlier larger Pistons, are later engine Pistons compatible? Any help, advice, knowledge, links are appreciated!

I'm not doing the work, just the shopping #workshopgimp

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All years of L20b use the same pistons, regardless of exhaust port shape. L18 pistons fit the bore, but they give you higher compression(not a problem if you're building a high compression engine). Have you tried Ebay? I've found alot of pistons on there.

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1980-1981 510 came with Z20 engine.

1977-1978 came with L20B

  

 

Ah right, thanks!

 

Why not order a set of custom pistons, like JE pistons in the UK? Cast pistons are less expensive than eBay.

As long as your boring oversize, get the largest that will fit -- it's free HP.

I'll look into it

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You can use L18, HL 510 early, or L28 pistons (280ZX)  I'd go .040 over.

FYI custom pistons at at least $500 / set

Yeah, I looked up custom and choked. Too much, a very last resort.

 

I just spoke to my engine shop, they say they need to bore to 86.8mm to clear the damage. Is a lot, but not too much, as I understand it. That said, there won't be an off the shelf piston that size anyway right? I'm searching the net, and ratsun, but it's tricky on a mobile device and I'm getting bogged down in info I can't quite piece together lol

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Use the off the shelf 1mm (.040" over) 280Z piston, since they need 86.8 to clean up the bores, just go to 87mm and be done with it.  HG may be an issue, but there is an answer.  ITM RY6134 040

Right, yes makes sense. Though am I right in saying dished Pistons from an earlier 280z/L28 would be better with keeping the compression down? Like part number ITM RY2700 040 for a '76 280z (I'm looking at Rock auto)

Also, would the stock L20b rods and crankshaft be ok with these?

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Though am I right in saying dished Pistons from an earlier 280z/L28

 

 

yes the pin heights are the same I think the piston is 10.9cc dished so you use the same rods.

 

make sure you irder l20bearings for the crank think they are biggers rods are the same I believe in all L motors.

 

 

86.6 might as well go 87mm but then harder to get I assume in those size pistons.

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make sure you irder l20bearings for the crank think they are biggers rods are the same I believe in all L motors.

Main/crankshaft bearings L20b or L28 ? Sorry, wasn't sure which you meant

 

Thanks for the help by the way, the knowledge on Ratsun never ceases to amaze me, it's helped a lot!

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main crank bearings are bigger on L20s than L28s I believe.rods are the same.Not that really matters for what your doing.I say find another L20 block thats in better shape if possible or another Lmotor

 

 

Not an option really, L20b is super rare in th UK, other L series still uncommon.

 

 

 

Be sure to specify L20B, as the L20A is a 6 cylinder engine.

Well aware of this yeah

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Piston prices, back in 2008, undoubtedly more know. Finding a local manufacturer will usually cost less. Buying direct is less expensive while using a middleman is more expensive.

 

 

PAECO Custom order $460/set

 

Ross Racing pistons $359/four without wrist pins

 

Venolia (part number 10400 for standard pistons, $67 each). Custom $86.00 each

 

 

The best thing about customs is you can get flattops or domed in any bore size desired. Flats make more power with better fuel economy than dished when fitted to a kidney/peanut head.

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