Frequently Asked Questions



After my engine is assembled with APC skirt coated pistons, what is the recommended break-in procedure?
The break-in procedure depends on the power level, engine type and how tight the piston coating is to the cylinder wall when it was built. If more than 75% of the clearance recommended by the piston manufacturer is taken up by the coating, then it is important to do heat cycles and create conditions that sequentially heat/expand the PISTONS in short bursts to higher and higher temperatures with time to cool the PISTONS at idle between intervals. The temperature of the pistons is related to the power so there needs to be a load on the engine when increasing PISTON temperature at each interval. This means that you can’t break in the coating on a run stand, or just doing heat cycles with no load present. If you have a filled block or a high-power engine for drag racing the pistons will expand faster so you have to be more careful on the break-in, or build in some extra clearance knowing that the pistons will grow quickly.
Water cooled vs air cooled, piston alloy/architecture, and other factors all contribute to the break-in schedule. As a rule of thumb, if you don’t know how an application will behave with Abradable Powder Coated pistons, then start off with more clearance and stay light on the power during the break-in. You can always go tighter on the next build.


Which type of break-in oil should I use?
Standard straight 30 weight oil works well for the break-in cycle. Synthetics or oil with zinc additives may be too "slippery" for initial coating break-in. After the break-in is completed, the oil can be drained and replaced with your preferred engine oil.

Packing and Shipping

How do I prepare my parts for coating?
New pistons – use the manufacturer’s packaging to ship
Note: Please be sure that the parts are “squeaky clean” to avoid cleaning charges. Many new parts still have the manufacturer’s machine oil on them which will also result in a cleaning fee. When ordering new pistons, you can drop ship parts directly to Line2Line™ in order to save time and money.

Used pistons – disassemble and clean completely
Remove pistons from connecting rods
Remove all rings, pins, clips, spirolocks, etc.
Degrease all surfaces thoroughly to avoid cleaning charges

Packaging - Parts are return shipped in the same packaging that they are received in
An OEM piston box is best Use dividers to keep parts from hitting against each other Wrap each part individually in bubble wrap, foam or heavy kraft paper

Newspaper does not provide sufficient protection against damage!


Piston Skirt Coating

How thin/thick can you apply APC?
As little as .00035” per side (.0007” diameter) to .010” per side (.020” diameter) or more

What is the price for APC skirt coating?
For up to .006” on the diameter: 1 to 3 pistons = $40/ea; 4 to 7 pistons = $38/ea; 8+ pistons = $35/ea; add $2.00 per .001” per piston for additional thickness over .006” diametric.
Pistons over 5” diameter, large diesel pistons, piston cleaning/degreasing and removal of rings, pins and clips all will incur additional charges. Piston coating costs are listed on the Order Form.


What is the turn-around time?
Standard, non-expedite processing time is 15 business days +/-. Expedited coating services are available for an additional cost, which are listed on the Order Form.

Does it matter whether the pistons are new or used?
No, our abradable skirt coatings work well on both new and used pistons.

What if my piston skirts already have a coating on them?
Preparation for coating includes removing any existing coating to insure the best adhesion.

How much weight does the coating add to the piston?
Do I need to rebalance the rotating assembly?

Even with a heavy build-up, the weight that APC adds to components is negligible so there is no need to rebalance any part of the rotating assembly.
This highlights another advantage of APC; you can coat your present pistons to fit a honed bore vs. boring .010” over and buying new oversize pistons, resulting in additional work and expense.


If I want to coat my pistons, will I have to change my clearances to accommodate the coating?
No, continue to use your preferred set-up. APC is designed to be self-clearancing and can be accurately applied to a thickness tolerance of .0005” +/-.

Which abradable coating is right for my application?
APC is offered in several different formulations. The engine and usage information that you provide on the Order Form will help to determine the appropriate formulation to use.

How do you know how much coating to put on my pistons?
Every Order Form includes a Thickness Calculation Worksheet. You can either specify a Target Coating Thickness based on your worksheet calculation or just indicate a specific thickness to be added to the piston diameter.

Can you coat the ring land area?
Yes, but it adds considerable cost to the job. Coated ring lands can help minimize rock-over and keep the piston straight in the bore in stroked engine applications.

Piston Crown Coating

Do you offer a crown coating?
Yes. ThermBar™ thermal barrier coating is an insulating/reflective type coating composed of ceramic and metallic materials

How thick is ThermBar when applied and cured?
ThermBar as applied is .002” thickness or less.

General FAQs

How long will the skirt and crown coatings last?
Many dry film lubricants are designed to be "sacrificial" and eventually wear out. APC is designed to clearance itself until the optimal fit is achieved. The porosity of the coating helps maintain the oil film that the piston is riding on. Theoretically, the coating could last indefinitely under these conditions. Barring any catastrophic failures, ceramic thermal barrier coatings are virtually permanent.

Can APC restore clearances of worn and scratched parts?
Yes. APC can be applied thick and is a cost-effective way to restore worn parts back to a “better than new” fit.
APC can fill scratches and gouges.
APC can be machined to size using standard machining methods.
Depending upon load, temperature and other operational factors, APC thicknesses of even .040” are possible


Which components can be restored using APC? Pistons
Oil pumps
Lifter bores
Wrist pin bores
Cam bores in aluminum heads
Press fits