Might remember my last post about coated bearings, well now i'm wondering about coating the pistons. I'm getting Diamond forged pistons with gapless rings, VRE said i should get pistons skirts for extra insurance... they also quoted me ~300$ to have the Diamond pistons coated on the skirts and the tops.

What i wanna know is if its worth the 300$, or if its kinda like the coated bearings (insurance for when things go wrong)?

Again, this is going to be on a DD blower lt1. Pump gas with ~15-20psi + meth/water injection. Might start running E85 when it comes available in my area.

 

On a DD I would say no.... not going to make a difference if you ask me

 

I would not bother with the skirts. I would coat the crowns on a blower car.

Rich

 

On this topic anyone have comments on how long coatings will last in a daily driver application?

 

I have seen factory coated pistons on the skirt and my Speed Pro pistons have the skirt coated. Must be something to the skirt part of it.

 

So i got a three way tie. Anyone care to break it?

 

You should have asked the question in two parts..... crown coating (not required, maybe not even a good idea on a nitrous application) and skirt coating (a good idea). I have the Swain moly skirt coating on my BME nitrous pistons.

 

Fred, why do you say that it's bad to coat the tops of nitrous pistons?

 

Interesting enough, after I had my crowns thermal coated I read in the Advanced Pro Trends manual that you loose hp but gain fuel ecomony. We are only talking a hp or two but I wasn't quite ready to read that.

 

When I had the 396 built, I went with coated bearings, and had the piston skirts coated on my J&E's, by them. Nothing done on the tops, except having them "buffed".



Nick

 

The TBC on the crown keeps heat in. That should increase power, since its all about thermal efficiency. And improved thermal efficiency should reduce fuel consumption, since that's where the BTU's come from in the first place. The question in general is how large is the gain, and whether that gain in thermal efficiency is worth the cost of the coating.

With regard to the nitrous pistons, notice that I said "may not be a good idea".... I assumed that it would be a good idea, but the shop that built my engine, and specializes in dry nitrous applications, said "no". They felt that it altered the heat distribution and heat flow through the crown of the piston in a negative way. It was hard for me to rationalize the way they explained it, but they certainly had a lot more highly successfull experience in building large-shot nitrous motors than I had ( = "0"). They provided an alternative to the TBC, which they made a good case for, but unfortunately, swore me to secrecy

 

The rationale for coating the crowns with a blower is to keep the temperature of the crown down. If it makes hp, all to the good. But that isn't the main reason to do it. It's to cut down the frequency of ordering new pistons!

Rich