ceramic coating pistons?

blertsie

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Location
South Africa,Pretoria
Car
Alfa Berlina1968 2L
Good Day
I am busy with a turbo conversion on a Old 2 litre 8v Alfa romeo motor
The standard pistons have a extremely high dome due to the hemispherical combustion chamber.
I found BMW pistons that is the same bore of 84mm and is flat top, it fits fine in the motor an drops the compression ratio down to 8.2 : 1.
I don’t think that the pistons will be able to handle a bit of punishment as I’m looking for about 400 BHP so I’m thinking of ceramic coating them but don’t know if that will make the piston more durable
Do any of you have advice?
 
Ceramic coatings on pistons are a problem. Getting a smooth uniform coating is not easy due to the nature of ceramic. The piston rings are the weak spot here so just coating the piston will not really make the piston stronger.

Forged parts are the way to go here. A ceramic block would be nice but again precision machining one is not easy.
 
Don't both with ceramic coating the pistons, gain vs. outlay it's just not worth it. Gapless rings too are another luxury, for 400hp decent forged pistons with normal rings will be fine. Proper mapping is the key; the best pistons in the world won't hold up to massive detonation and heat.

What about your rods? 400hp isn't massive for a 2ltr turbo but it's past what a lot of standard rods can take and I imagine you'll be running quite a lot of boost at 8.2:1 to acheive that, over 1.8bar I would say depending on head and rest of the setup.
 
i already have JE forged rods and arp bolt kit for the motor and 650cc injectors and a gotech pro x management system
the only problem is the price of the forged pistons
 
Try those BMW pistons then with spot-on mapping you never know you might be ok. The problem is the amount of boost and therefore heat you're shoving into the cylinders. Depends if you're willing to replace various components if any of the pistons melt vs. fitting forged pistons in the first place and forgetting about it.
 
Seems a waste of time and money when you could just save up and fit forged pistons in the first place. Cost of new HG and possibly bolts for doing it twice instead of once? Re-honing or re-boring again too?

It's your car though bud so the best of luck with it.
 
Out of curiosity MA, would standard pistons given the Cryogenic treatment be better than a forged version do you think?
 
Probably not, I don't know anything much about this Cryogenic treatment and have never heard or seen a car using any treated parts. When silicone-less forged pistons work fine for 1000hp builds I'm not sure there's a need?
 
Probably not, I don't know anything much about this Cryogenic treatment and have never heard or seen a car using any treated parts.

Actually neither have I MA except with what I have read on their website (With kind thanks to TN for that!) I am very interested though and need to do some more research into it, I need to see if it is fact or fairground bunkum! ;)
 
It is very much a fact, you get smoother metal surfaces and stronger metal but it wont make as much difference as fitting forged parts. Now cryo treated forged parts would be something special! :D
 
Actually neither have I MA except with what I have read on their website (With kind thanks to TN for that!) I am very interested though and need to do some more research into it, I need to see if it is fact or fairground bunkum! ;)

cant comment on internals but i had Nitric cryo treated discs. after nearly 2 years, and bout 25k with some heavy braking,there wasnt even a lip on the edges
 
I'd stick with those BMW pistons and look into water/meths to keep the piston crowns cool. Should keep your combustion chambers clean also.
Also stronger and stiffer rods would be higher on my list than more resilliant pistons.

Cyrogenic treatments are worth it for someone like Oz who's running big power and as said before it makes the metal surfaces more uniform and smoother making them harder waring rather than stronger. There is infact some power gains from just cryo treatment but not mega amounts also life span of the engine also improves as do mating surfaces so your pistons and baring shells are more likely to have a better fit.
 
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