Piston Modification

Walter Prechsl

Some days ago I was by Helmut Wahl of Fellbach near Stuttgart/Germany. I brought him my pistons to modify them at the newest knowledges. My actual problem was that the gudgeon pins were too tight in the bores, they moved hardly and from my last years visit with my spare engine I knew that Helmut makes special modifications for a better piston lubrication and a lesser oil consumption.

Following did he modify:

-- At the upper rim of the pistion he milled a triangular notch in - this is one of the newest knowledges at Porsche. That makes the compressed air not to strike at the ring, but makes a squirl and puts his power at the pistion. The same between the 1st and the second ring. It should give about 1% or 2% of additional power!

-- At the second compression ring he lathed a "nose", that is a modification, looking like a nose to scrape the oil from the cylinder wall.

-- The bridge between the 2nd ring and the upper oil scraper was milled a little bit down to keep the lublication.

-- under the upper oil scraper, where the oil holes come out, he made a little tapering, to let the oil better go down.

For all that I paid about US-$ 50, a very reasonable price for that very special work. You can find Helmuts address at the suppliers list. He works for motorbuilders all over the world and is very well known at racing companies.