Gudgeon Pin to Top of Crown heights
Turbo Mini Forums

Hellooo,

Im planning on using AE 21253 pistons, after a bit of research i found a site that said they all have just under 9cc of dish, but they vary in pin to top of crown height, is this correct ?

If so, which is the one to go for?

also, what compression ratios do people run when using said piston ? and how did you achieve it.

Many thanks!

Dave

Dave the Cake

21253 will give a CR of 10.5:1 and was used in the MG Metro.
21250 will give a CR of 10.0:1 and was used in Unleaded versions of the MG Metro
21251 will give a CR of 8.8:1 don't use these they're shit.
All have 9cc dishes but different pin to crown heights to achieve the different ratios.
Are you planning on using the 21253's in a boosted engine?

oh thats intresting!, the engine i have is a vandem plas, so hopefuly ill already have 21253 pistons!

yeah i am planning on turboing the engine with 21253 pistons, gaining a lower compression with opening up the chambers. i think im going for 8.5:1 i know i will need to take alot out of the head tho. hopefully its possible.

do you have any information on the range of differnece in pin to crown heights? do they differ much? as in, is it enough to warrent me selling one set to get another, instead of just taking more out the head.

Thanks for your reply n.g.l

Dave the Cake

I dont recall seeing any diff in 21253 piston crown heights tbh, i could be wrong. Plus i dont think sitting the piston further down the bore is a good answer to lowering cr.

1/4 Mile 14.3secs 96Mph Terminal 10psi of boost.


Fibreglass Parts? - http://www.tdkracing.co.uk/
Split Rims? - http://www.force-racing.co.uk/

fair point!, guess thats answered my question then :)

Dave the Cake

Be very careful how much boost you have, as these pistons are not ideal.