The Ford Barn

Patrick L. · 03-09-2015, 07:03 PM

Some 'newer' engines do run clearances of less than .001". This depends on what the piston material is and the purpose of the engine.

Ford uses several different pistons in basically the same engine depending on how the engine is outfitted. The supercharged units use a forged piston with less than .001" at the 'normal' measuring position but is tapered to allow .0025" at the bottom and at BDC. They are still trying to figure out some failure issues due to detonation, most engines can handle a fair amount of detonation if not supercharged. It appears they are having some ignition timing issues causing failures under high boost.

I've been playing with supercharged engines since I was 15 and have grenaded my share.

I had a Tundra POS which went thru 3 engines [pistons] in less than 30K miles due to coated piston failures and tight clearances. I don't know the clearances because I never got near enough to be able to measure, they got rid of those engines as soon as they could. But they supposedly ran them tight.

03-09-2015, 07:03 PM	#1
Patrick L. Senior Member Join Date: May 2010 Location: Largo Florida Posts: 7,225	Re: Tight Piston Clearance, Not Model A Some 'newer' engines do run clearances of less than .001". This depends on what the piston material is and the purpose of the engine. Ford uses several different pistons in basically the same engine depending on how the engine is outfitted. The supercharged units use a forged piston with less than .001" at the 'normal' measuring position but is tapered to allow .0025" at the bottom and at BDC. They are still trying to figure out some failure issues due to detonation, most engines can handle a fair amount of detonation if not supercharged. It appears they are having some ignition timing issues causing failures under high boost. I've been playing with supercharged engines since I was 15 and have grenaded my share. I had a Tundra POS which went thru 3 engines [pistons] in less than 30K miles due to coated piston failures and tight clearances. I don't know the clearances because I never got near enough to be able to measure, they got rid of those engines as soon as they could. But they supposedly ran them tight.