hullstu123

recently destreyed a piston a my pride and joy p1, :{ not long after doing the self and same thing to my track day scoob... now in my track day car i replaced the pistons with mahle forged items with a 25 thou clearance and had no problems with it whatsoever but my p1 is my daily driver and im a bit worried about my short commute to work not giving time for pistons to expand... so just putting this out there to see if anyone can give me advice on which pistons and how much clearance to run etc etc without sitting on my drive waiting for the car to warm up every morning which in my track day car is not a problem any help would be greatly apreciated,

MOTORS S GT

iTrader: (2)

It depends on what material your forged Mahle pistons are made from, 4032 or 2618, & I would think you mean 0.0025" clearence, if its 0.025" you would be able to hear it from space.

hullstu123

yeah thats what i ment ;] im not sure which ones i used in my track car but that clearance is what i was told by the supplier to run, this is all new to me, im a time served mechanic and i do quite a lot with subarus but i dont want to spend a lot of money in the wrong direction for something thats not suited for what im going to use it for...

MOTORS S GT

iTrader: (2)

You really want the 4032 high silicon for a road application, honed to 0.002" to 0.0025", if its the 2618 low silicon which you should use for your track focused engine it requires a bigger clearence, 0.003" to 0.0035".

hullstu123

thats great thanks for your help... whats the difference between the two ? its something i have never really looked into

hullstu123

and i dont suppose u could tell me how u indentify what heads i have ? there shimed not hydraulic but thats as much as i know ;]