piston ID
Turbo Mini Forums

I am rebuilding my engine All signs say it was a turbo block.
I.E oversize bearing in clutch housing
Valve stems of different sizes 7 and 8mm
But when I saw pistons they had no markings so I went and got myself a set of std turbo pistons, Just to make sure

But when I Removed pistons from engine and checked sizes I found the block had been over bored by 40 Thou, Now I don't mind but the pistons look fine and useable but the only ID I can find are


KP 92?? This is on the inside of pistons
On the surface I can make out M .030H
the bore is 71.33 they came out of

Does anyone recognise these numbers I noticed the turbo std pistons where 1mm deeper dished than these but as they are a 1mm wider would this make the diff in dish depth.

Can anyone throw any light on this please.

forgot other question is it beneficial on a turbo to increase valve sizes as I am working my head as well

can you bash some pics of the pistons up?

They are probably going to be ok as they are likly to be after market, but a picture says a thousand.....

biger valves are worthwhile, but don't go mad, something like 36x21 should be good.

TurboPhil or Benross on here both do good head work at good prices, might be worth looking at geting one of them to do the head.

The fact you asking the question say's to me you need to research what you are doing more.

I would ask some of the real experts like Turbo Phil and Benross for advice.

I am sure they will soon fill you in

Here's a link to photo of pistons that are oversize
http://www.flickr.com/photos/99585911@N02/9415469311/

Hmmm I'm not sure about those pistons, they look like they might have slots rather than drillings behind the Oil control ring, in which case they might be prone to breaking up at high rpm/with det.

Anyone else seen that style?

I am trying to get 140 - 150 BHP.
I have a rs intercooler, std metro T3 Turbo and head work I am doing with a friend of mine , I have just rebuilt the turbo

I have rebuilt 3 other 1275 std engines but am new to turbos so am trying to get my head round compression and boost as far as I can see I need to go for 8.5.1 to get my desired bhp and run about 12 - 14psi boost but how does increasing the valve sizes effect this could I go down on boost pressure

Your aiming at the right kind of figures,

you could up the compression slightly, up to about 8.8 or so,

as a general rule with a better head you need less boost for a given hp but you probably guessed that,


the main thing you need to be worried about is those pistons, if they are pants you'll melt them.

that sounds like a good choice, the turbo pistons are nice and strong,

If you go for 8.5:1 then if you dont hit 150 you have scope to up the boost a bit so you do.

I'd advise a cam change too, MG metro or Kent 266 should be good, just that bit peppier than the std turbo cam.

Also fitting the oil jets under pistons

BMW ones?

Don't know I saw the mod on turbo-mini.com and liked it he uses ford v tec but what ever best and easiest anyone got any photos of theres fitted

Edited by neildanks on 1st Aug, 2013.

the BMW ones are easier,

check page 5 here...

http://www.turbominis.co.uk/forums/index.p...d=191396&fr=100

thanks that was really usefull to me that's the ones I going for just need to find oil gallery along line

sorry ive gone off subject can anyone id these pistons before I sell or keep them for a future project

On 1st Aug, 2013 neildanks said:
Don't know I saw the mod on turbo-mini.com and liked it he uses ford v tec but what ever best and easiest anyone got any photos of theres fitted

On 1st Aug, 2013 Joe C said:
BMW ones?