Technical Q about L28 'flattop' pistons.

[jonbills]

Hi everyone -
My new L28 has these pistons with a raised circular dome on them.

(The one on the right in the pic - borrowed from a hybridz.org thread)

Does anyone know what volume the raised dome has? I need to figure out if it's significant in compression ratio considerations.

Thanks in advance.

 

[Mr.F]

From memory 2cc.

 

[jonbills]

Thanks Mike. Not insignificant then - makes a few points difference.

 

[jonbills]

I've finally got my L28 cleaned up and measured, and the bores and pistons are pretty worn - so looking at finding some forged replacements at 88mm or so.

These Kameari ones seem nice -
http://www.rhdjapan.com/kameari-street-piston-kit-l28-l30-for-l28-rods.html

Has anyone here got experience of them? good/bad? looks like they're floating pin, so would I be right assuming my stock rods would need to be bronze bushed?

I did do a search of old threads, and saw some people claiming to use Kameari pistons, but can't tell if they were these and no comment on rod/pin treatment.

 

[camerashy]

I've finally got my L28 cleaned up and measured, and the bores and pistons are pretty worn - so looking at finding some forged replacements at 88mm or so.

These Kameari ones seem nice -
http://www.rhdjapan.com/kameari-street-piston-kit-l28-l30-for-l28-rods.html

Has anyone here got experience of them? good/bad? looks like they're floating pin, so would I be right assuming my stock rods would need to be bronze bushed?

I did do a search of old threads, and saw some people claiming to use Kameari pistons, but can't tell if they were these and no comment on rod/pin treatment.

Hi Jon,

I've got the datsunspirit.com pistons in a 87mm overbore, which are just rebadged kameari pistons. My engine builder is due to finish the whole engine build on Friday, and he's using stock L28 (albeit polished and peened) rods so I can ask him what he did when I see him and get back to you?

These be them

Last photo showed one of the pistons damaged in shipping, Eiji replaced it free of charge.

James

 

[jonbills]

That would be great. Thanks James.

 

[SKiddell]

Hi James

Ive used slipper pistons like that before and just a word to the wise, they often "slap" like a pig on cold start, (forged often have more cold slap than cast due to expansion rates) but short shirts are even worse, good luck with your build.

 

[SKiddell]

would I be right assuming my stock rods would need to be bronze bushed?

Yes but youll be looking at around 20 - 30 per rod, then they need peening and polishing etc etc or alternatively use some forged rods (they can be had for small money these days and are +/- 1 gram out of the box), ive spent hours trying to balance OEM rods....never again, forged every time given the choice.

 

[jonbills]

Thanks Steve. Kameari offer a forged Pistons & rods kit, but that's getting on for £1500 compared to £750 for just the Pistons .
Is that about right, or are there cheaper good options for forged rods?
I see some Chinese ones on eBay....
http://www.ebay.co.uk/itm/321423701113

 

[SKiddell]

pm me

 

[camerashy]

Hi James

Ive used slipper pistons like that before and just a word to the wise, they often "slap" like a pig on cold start, (forged often have more cold slap than cast due to expansion rates) but short shirts are even worse, good luck with your build.

Hehehe

It's funny you say this, I have an 05 Subaru Legacy GT wagon...just had a full engine rebuild with forged JE's, believe me, I know from experience what a slappy engine is line, the boxers are among the worst for it, usually because the builder hasn't given enough space for ring expansion.

The builder for the L28 in Toronto, ECI engines was freaking out a while back as the rings (kameari pistons come with wiseco rings) didn't spec the metallurgy on them, and he wanted to know the composition so he could bore the block with the right clearances. Thankfully Eiji had included all the soecs of what they needed.

I am definitely excited to be getting it back, should be collecting the long block this weekend. I just wish that someone like Rusch motorsports wasn't so far south of the border.

James

 

[Alphabettispaghetti]

The forged rods on eBay have been used to good effect. Good enough that I'll be using them for my engine build.

 

[jonbills]

Thanks Franky - what pistons are you using in your build?

 

[Alphabettispaghetti]

I've some forged je ones. 240z block 1mm over, with a 280 crank and short rods to suit the pin height. Should be about 2.65ltrs I think. Can't remember off hand as its far too long since I've thought about it and/or seen it. I want a revvy engine in the original block. With a high diff ratio for a 'fun cammy' drive.

 

[jonbills]

ah - thanks. Do you have a link/reference for the JE pistons? lots of people seem to have them, but their website says they don't do them :-(

 

[Alphabettispaghetti]

ah - thanks. Do you have a link/reference for the JE pistons? lots of people seem to have them, but their website says they don't do them :-(

Hi, I haven't at the moment but could get the details off the box. They came from Laurence at Star motorsport, with the custom pin height I guess its to give a cheat spec engine to suit a 2.4 block

 

[jonbills]

Thanks Franky - could you get that ref off the box? I'd be grateful.

Is it a custom pin height or standard? With the switch from short throw 240 crank to long throw 280 crank in the same height block, you'd always need a shorter rod surely.

I.e. Isn't your build spec essentially an l26 with higher quality internals? (So 2565 cc)

 

[Alphabettispaghetti]

Hi, Can't remember the details off hand, once I'm home from working away I'll see if I can find the box and get the details onto yourself. All I can remember without my notes I'd that it should give me the type of feel I was after.

 

[camerashy]

Jon,

I've just done an update on my engine build on retrorides -

http://retrorides.proboards.com/post/2030845/thread

I asked Emilio (who has built more than a few L6's in the past) what he did with my pistons/rods. He did a freeze fit, i.e. heat the stock rod end and slip over the pin with a slight (few thou?) crush fit. I asked him specifically about the bronze bushing...for my engine, a street build, not necessary, for a race car, sure.

He suggested you look at the same pistons I have (which are the L28 datsun spirit pistons) which have a much longer skirt than the super light pistons, he found them very nice to work with.

I'll put up a couple of finished photos on Saturday when it comes home can't wait to get it all hooked up with the manifolds, exhaust and such and get it running.

Cheers and good luck!
James

 

[Alphabettispaghetti]

I don't think I'd go for pistions where the tips have been engraved.