je pistons
Turbo Mini Forums

saw 23cc dished pistons today, scary...

The only block these would reliably work in by the sounds of it is an original S block skimmed to the 970 spec with connecting rods and push rods to match???

Might bring then flush to the top where you idealy want them

All this trouble at a price like that, youd have though they would have got it right.

I recon they may be originaly for a motorbike engine, what with the narrower pins and lower compression hight, as not many engines in the US use small bores like that of the Mini. My 74mm rings from Total Seal were a custom selection of from the motorbike section of the catalogue.

JE do not list a piston for the Mini, but then who else in the uk sells the JE pistons for the mini other than MiniSpeed. Maybe they have them custom made and pehaps they got the copression hight way wrong

Edited by Sprocket on 31st Mar, 2006.

pehaps the avon bar acrolites must be custom made for are application.

when spending £400 you should have all the hassle of bushing conrods and skimming loads of meat of ones block

always looking for them bigger bunches of bannanas

An allegro block skimmed is as good as a 970 block. no problems what so ever! mine is skimmed 7 mm without problems at all.

i spoke to minispeed, and the reason they are shorter is the ring are closer to the gudgeon pin, so then the height has to be brought down to reduce the risk of detonation. the piston are made by je to minispeeds design.

words fail, why design a custom piston which isnt suitable for its application.

i bought my forged pistons from MED, the newer forged ones with the same little pin etc etc.... These fortunatly were only 125 thou down the block, but that was prob because of the short 76mm crank

was thinking of running the JE's myself, am so glad i didnt now. Harsh luck dude.

Edited by andeh on 1st Apr, 2006.

I've seen the future and tbh its Pie

I bought 15cc forged omegas.

They fitted straight in with no fucking about needed whatsoever, deck height 25 thou once my block had been flashed over.

THAT is how it should be if you are spending £400-odd on pistons.

I think a smaller gudgeon pin is a good idea, but they should tell you before ordering though..
Also, a lower piston is also a very good idea!
Remember that the ultimate piston is not one that fits easily and takes little machining.
The piston to crown height on the A series pistons is too bic to be honest.l
I think that these pistons sound great!

I would agree Vegard, the problem here is the lack of info!There is no problem skimming the block so they are flush.

Dave, what's the problem?

Smaller gudgeon pin= great idea
Lower pin to crown distance= great idea

The fact the they do not fit right out of the box is not that much of a problem in my mind... The smaller pin also makes it easy to use fully floating pin which is also a good idea!

My problem is that these almost certainly need different pushrods to be anything like optimal in the valvetrain geometry.
Skimming that much off a block whilst being a great weight saving is useless for anyone doing something like the 16v BMW head.
Smaller pin - great idea in principle - but show me one person who has a performance or reliability problem with the stock press-fit pin.

If they're going to sell these - they should be making peeps aware of the issues. That said - I guarantee minispeed don't give two turds about the rocker geometry... Certainly don't think i've ever heard of a minispeed engine winning a race.

I'm not saying that the stock pin is bad, this is only lighter :) Good idea :)
Shorter pushrods? MED sell tubular pushrods that aren't that expensive to be honest.

But, I do fully agree, the salesman should make the customer wary of these requirements!

Can some one run that by me again why it is good to skim nearly 6mm off the block face and why Minispeed in their wisdom decided to design a piston with lower compression hieght when every big name tuner still uses the standrd compression hieghts, whether standard, forged or custom made pistons, that actualy fit without problems.

Also if its such a good thing, why has it not been done more often in the 50 years since the engines conception. I still think MiniSpeed fecked up on the design (maybe converting mm into imperial for those americans, or maybe it was the Emericans themselves) and are trying to get rid of the stock without loss, I dont know

Skimming an A+ block 6mm leaves little thickness in the block face and may well result in flexture of the face resulting in poor sealing of the head gasket, and this on a N/A engine, never mind a turbo engine, is never a good thing. There aren't many Cooper blocks left and the ones that are near standard bore are few and far between

The s block are not the best to skim this much. Pre A+ ones have no problems beeing skimmed 6-7 mm what so ever, about A+ I dont know.

Out of curiosity why do you need as much deck height as possible with the BMW head Dave?

You don't need deck height - but deck thickness (because the new studs end up close to whee the three large water holes are - hence a thin casting here is useless)...

ah, i see, you need some meat for the studs to thread into. I have bored all my studholes down into the water, but of course they are still placed in the normal spots, so I have sufficient thread engagement. There is no water comming up either as I am using a type of sealer on the threads.

Make sure you use a steel tube and head nut to torque up the studs when using seal on the threads, while it is still wet, thus prventing the sealer giving when it is dry after the head is fitted and torqued up and going through hot cold cycles

Edited by Sprocket on 2nd Apr, 2006.