Venolia Forged Aluminum Racing Pistons

by Jeff Lucius

Venolia Pistons & Rods
2160 E. Cherry Industrial Circle
Long Beach, CA 90805
Part Number: 3620 phone: 562-531-8463 Job Number: 117853
fax: 562-633-9439
ENGINE
Mitsubishi 3000GT
6G72		 New Bore: 3.637 in. (92.3798 mm) New Compression: 8.2:1
Stock Bore: 3.587 in. (91.1 mm) Stock Compression: 8:1
Stock Stroke: 2.992 in. (76 mm)
Rod length to stroke ratio: 1.855
PISTON
Diameter: 3.632 in. (92.2528 mm) Pin:0.866 X - Rings: 0.060 / 0.060 / 40
RECOMMENDED CLEARANCES
Piston Clearance Top of Skirt: 0.008-0.010 in. (0.2030-0.2540 mm)
Bottom of Skirt: 0.005-0.007 in. (0.1270-0.1778 mm)
Ring Clearance Side Clearance: 0.003-0.004 in. (0.0762-0.1016 mm)
Ring Gap: 0.004-0.005 in. per inch of bore
Pin Fit 0.0006-0.001 in. (0.01524-0.0254 mm)
CONTENT (nominal)
Alloy Number: 2618-T61 Cu 2.21%; Mg 1.2%; Fe 0.98%; Ni 1.08% Coatings: none; Silicon: 0%

The industry standard is 2618-T61 aluminum forged pistons when strength and durability are the prime considerations. Silicon-aluminum alloys have great wear characteristics because the silicon particulate hardens the alloy and reduces the thermal coefficient of expansion. However, silicon-aluminum alloys can turn brittle and become prone to fracturing when subjected to extreme stress. The failure rate of silicon alloy pistons in severe-duty, racing applications is quite high. With a piston made of a silicon alloy, such as the 4032 or MS75, once a crack starts, it doesn't stop until the piston suffers a catastrophic failure. In the rare case of a crack in a 2618-T61 piston, the crack will migrate to an area of lower stress and stop. 2618-alloy pistons keep their shape under extreme pressures and high RPM's. The result is proper ring seal and high heat transfer plus greatly reduced cylinder wall failure. (Adapted from Bill Miller Engineering and Flatlander Racing promotional material.)

People have asked me why I chose Venolia pistons and how have they worked out. Here's the story.

Back when my engine failed, August 1997, I did not know a lot about these cars and so pretty much just followed the advice of my engine builder and the speed shops.

I told my engine builder I wanted to use forged pistons - my goal was a 500 HP daily driver. He suggested Arias and so he ordered them. The things never arrived - lost in the mail or stolen. I said then I would take care of getting the pistons. I contacted one of the few speed shops then helping 3S owners - St. Andre's. Eric St. Andre said he could help me out and ordered me some forged pistons. We discussed oversizing and agreed 0.050" would probably be fine. I don't think I knew at the time if Venolia was the manufacturer. And even if I did know, I would not have recognized the significance. It took 12 weeks to get these little jewels and they were beautiful. A real shame to have to muck them up in inside an engine. I paid just under $1000 including moly rings and pins and ~$30 shipping. I have heard recently that Venolia pistons sets with rings and pins only cost around $700.

So I got the Venolia pistons out of no deliberate effort of mine and kind of by accident (thanks to the Arias pistons reported being lost). At the time, I had not heard of any of the piston manufacturers I list on my web page (2-pistonguide.htm) and so made no conscious decision to select one or the other when buying the Venolias. I contacted Venolia directly to get supplemental info for the data sheet they supplied with the pistons.

I have abused these pistons moderately with many instances of high detonation (datalogger counts over 20) and high EGTs (over 1000ºC). The pistons have developed no problems that I am aware of. Start up "rattling" is unnoticeable. Some of this may due to my engine builder trimming (or saying he did) the lower skirts a little. In any case, there is no noticeable "diesel" sound - just the familiar tickings our engines have.

For more information and pictures regarding these Venolia forged pistons please visit 2-venolia_wjc.htm
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Page last updated October 29, 2003.