N20 Piston Coatings

I've heard there are certain kinds of coatings to put on forged pistons for N20 use. I also heard some coatings only go on the top of the piston and a differend kind on the skirts.
Do the manufactures put this on and what is used, the cost and benefits?

Thanks

I will move this over to N2O Tech since you are asking general tech questions that are specific to Nitrous.

Thanks bud.

The coatings are not just for nitrous. The coating on the piston crown is a thermal barrier/heat reflective coating to keep the heat of combustion in the expanding gasses instead of heating (or burning) up the piston. The coating on the skirt is a dry film lubricant to prevent bore scuffing and reduce friction slightly. There are all kinds of places to put coatings like these in an engine: combustion chambers, valves, valvesprings, intake manifold... Yes, the manufacturers apply the coatings in most cases. Prices will vary, and so will performance gain. Two good places are HPC (www.hpcoatings.com) and Swain Technology (www.swaintech.com).

Pete above pretty much covered it. I've used it on the last two blower motors I built. I used Swain on the first one (have to ship the pistons to them) and Techline on the second (found a local applicator shop for this although you could do it yourself).

Because of the lowered temp in the piston itself from the barrier coating it's cheap insurance against detonation in a blown or nitrous engine. I was able to run 15 psi of boost with no intercooler on 91 octane pump gas on a blown EFI big block. This was with the air temps exceeding 200 degrees, still no detonation. The coating is the only reason it worked.

Jody

thanks guys

What does it cost for pistons?

I justed looked at both web sites. Looks like the cost for pistons is about 250-350.
Have any of you guys had your bearings done? or Valves

Thanks

I wouldn't worry about the valves, bearings, or combustion chambers yet. Bearings can be replaced and cranks can be reground, but if you burn a piston or scuff a bore you're looking at new pistons and a bore and hone. Build yourself a solid shortblock first (definitely with coatings on the pistons), and you can have valves, heads, etc. coated later as money allows or when you replace parts anyway.
I myself have not had any actual experience with engine coatings yet, but I want to put them all over the place in the next engine I build. ;)

IMHO the most bang for the buck is coating the piston crowns. I have used Swain with good results. After the crowns I would do the combustion chamber and valves before the skirts and certainly before any other wear type components. Most hi-po motors break before they wear out!

Rich Krause

rskrause has a point. You'll gain the most power by keeping the heat of combustion pushing on the piston instead of warming them and the heads up. Even though most of an engine's internal friction comes from the ring package, I'd still get the skirt coating for peace of mind if nothing else.