11 replies to this topic

[minisam92]

i was just wondering which pistons are better suited to pritty much standard 998 dished top or the flat top ones if any one can shed some light on this it would be appericated

[mini_mad69]

Flat top will give a higher compression ratio, and more MPG and more power.

[minisam92]

Are flat top standard?

[mini_mad69]

Depends on the year.

But yes, a lot of them came standard with flat tops

[minisam92]

ah might check mine when i do the crank thanks for the advice pal

[liirge]

Technically speaking dished pistons are better in general.

[indymini]

Technically speaking dished pistons are better in general.

Why are they better if flat tops have higher compression ratio and better mpg?

[jaydee]

better flowing charateristics, but i prefer flat tops.
Best pistons? D shaped.

[minisam92]

so should i fit flat top ones to my 998 ?

[jakejakejake1]

Well I think it would depend on the set up, and which head is being used etc.
In general flat tops will give a higher compression ratio, which in general is better for the above stated reasons.
But some applications may require a lower compression ratios, for example turbo cars.

[liirge]

Yer its all to do with flame propagation, if you just took a second to search on Google you would see why dished pistons are better in general

[Cooperman]

A dished piston is best in pure combustion technology terms. However, in practice it makes little difference. The important thing is to get the compression ratio correct and the A-series does thrive on a high-ish compression ratio. If you go for about 10.2 you'll have it about right. So you measure everything, do the compression ratio calculations and then machine the head to give the desired capacity. You cannot just fit, say, flat-topped pistons and hope for the best.