Pistons

[robi1000]

Hi everyone!

We are rebuilding my F7R engine (megane BE and ported willy head) and we found something strange. :) I believe my pistons aren't original items. They are absolutly flat on top. Can somebody tell me downsides of this design (perhaps air and fuel not mixing as they should...)?

Thanks for your answers,
Robi

[MAXIBOY]

think they are flat standard mate. high performance ones are either domed or dished for turbos.

[robi1000]

I found this picture on the net and I'd like to know if this piston (F7R) is standard or not.

http://www.email.si/apps/es_gallery/p.php?id=436523

[Bayliss]

yes mate the F7R piston is correct, i rebuilt mine aswell, deffo the original item

[Yanoo_]

Check this page: http://www.clio-williams.net/Parties/Entretien/Tuto.php?ent_id=21
(an F7R engine rebuilding in pictures)

http://www.clio-williams.net/Parties/Entretien/refaire_son_moteur/16_15.jpg

[Coops]

the standard F7R piston is lightly dihsed as shown in those pictures, F7P pistons are flat on their crowns with just the valve cutouts.

where did the engine come from? are you 100% sure of its history and that its definatly an F7R?

[MAXIBOY]

good call coops...

[robi1000]

It's definitly F7R. So the pistons are not original. We are replacing piston rings and I had to know.

[Coops]

i'd be questioning why the pistons have been altered, if they are not dished like F7R items then the comp ratio has been raised, but not normally as uprated pistons to raise comp will be domed. effectively the engines cubic capacity has been dropped to nearer 1.9L? :?

unless am missing something completely!

[robi1000]

We have to measure them and compare them to original piston dimensions. But I think they are as high as original pistons so there is no drop in cubic capacity.