skimmed pistons/squish/deck height
24-02-2012, 05:19 PM
#1
Wahay!! I've lost my Virginity!!
Thread Starter
iTrader: (1)
Join Date: Jun 2007
Location: mansfield
Posts: 83
Likes: 0
Received 0 Likes
on
0 Posts
skimmed pistons/squish/deck height
hi to all,
got a few questions for all u techies out there,
i m going to rebuild my tired old 2wd sapphire cos engine.i ve managed to get old of some cheap 0.5 oversized mahle pistons that have done very little miles. the problem is that they ve been skimmed 1.5 mm (compared with standard deck height pistons).this will make the squish clearance massive.what i want to know is that if i get the block decked 1.5mm to get the correct squish gap back will it work? obviously i would have to get the pistons machined to the same spec as standard to get correct comp ratio etc but this is nt a problem.i ve read that skimming pistons on a turbo engine to lower comp ratio is quite common but i think this method is cheap and nasty and will drastically alter the squish clearance which is a very important characteristic of an engine.basically will this work? will it lower the cc s of the engine? etc etc .
any info would be great.
thanks
got a few questions for all u techies out there,
i m going to rebuild my tired old 2wd sapphire cos engine.i ve managed to get old of some cheap 0.5 oversized mahle pistons that have done very little miles. the problem is that they ve been skimmed 1.5 mm (compared with standard deck height pistons).this will make the squish clearance massive.what i want to know is that if i get the block decked 1.5mm to get the correct squish gap back will it work? obviously i would have to get the pistons machined to the same spec as standard to get correct comp ratio etc but this is nt a problem.i ve read that skimming pistons on a turbo engine to lower comp ratio is quite common but i think this method is cheap and nasty and will drastically alter the squish clearance which is a very important characteristic of an engine.basically will this work? will it lower the cc s of the engine? etc etc .
any info would be great.
thanks
24-08-2014, 10:37 AM
#4
Too many posts.. I need a life!!
Unfortunately it would not be that simple. The squish area of the head is not an exact shape (cylinder) all the way up to the valves - whereas the piston is perfectly cylindrical. So, a 1.5mm slice of the top of the piston wont be the same as removing a 1.5mm slice of the squish area of the head.
I guess in theory you could probably do some volume based calculations and make it work.....but imo, get some new pistons and be certain it will work. It would be a lot of work to have some disapointment at the end of it all.
Matt
24-08-2014, 12:57 PM
#5
Wahay!! I've lost my Virginity!!
Thread Starter
iTrader: (1)
Join Date: Jun 2007
Location: mansfield
Posts: 83
Likes: 0
Received 0 Likes
on
0 Posts
Unfortunately it would not be that simple. The squish area of the head is not an exact shape (cylinder) all the way up to the valves - whereas the piston is perfectly cylindrical. So, a 1.5mm slice of the top of the piston wont be the same as removing a 1.5mm slice of the squish area of the head.
I guess in theory you could probably do some volume based calculations and make it work.....but imo, get some new pistons and be certain it will work. It would be a lot of work to have some disapointment at the end of it all.
Matt
I guess in theory you could probably do some volume based calculations and make it work.....but imo, get some new pistons and be certain it will work. It would be a lot of work to have some disapointment at the end of it all.
Matt
Trending Topics
24-08-2014, 06:32 PM
#9
Too many posts.. I need a life!!
Thread
Thread Starter
Forum
Replies
Last Post
SMILER258
Restorations, Rebuilds & Projects.
36
28-09-2015 09:04 AM
rog
General Car Related Discussion.
5
04-09-2015 07:24 AM