CincoBoy Posted August 3, 2015 Share Posted August 3, 2015 I pulled these from a spare L24 laying around. Besides the brand (Venolia), I have no idea what they are. The diameter is about 83.5mm. They have quite a dome shape. Any information, such as compression ratio or whether they are forged vs cast, etc... I would greatly appreciate! Thanks! Quote Link to comment Share on other sites More sharing options...
Pac_Man Posted August 5, 2015 Share Posted August 5, 2015 I took a look at their website and my impression is that the pistons are custom made to order. Initial look at the surface of the piston tells me they are probably forged, and Venolia's website states they make forged pistons. Given that the difference between the dished and flat top L28 piston dish CC is 10.9 CCs and the resulting difference in compression ratio seems to be about another 1.5:1, I would probably guess somewhere around a 10:1 compression ratio with an E88 head. It is just a guess, though. If they're actually custom it would be difficult to know for sure without measuring with the head on the block. Quote Link to comment Share on other sites More sharing options...
JavelinZ Posted August 6, 2015 Share Posted August 6, 2015 Venolia is a good piston quite a few AMC guys were putting those in their builds back when I was putting my car together. Everything was made to order so brand or size didn't matter. You'd have to mic the piston to get the specs, since Venolia makes them per the customers specification. Quote Link to comment Share on other sites More sharing options...
ryant67 Posted August 6, 2015 Share Posted August 6, 2015 I'd probably make a mold of the dome in plasticine or something. Measure the volume of the dome by capping the mold with perspex sheet with a small hole, then filling the mold with distilled water from a burette. That will give you the volume of the dome, then you just need to do the calculations to know what compression you will get with that figure. Basically the same procedure as for CC'ing a cylinder head, but on a mold of your piston dome. Quote Link to comment Share on other sites More sharing options...
Tony D Posted August 6, 2015 Share Posted August 6, 2015 Yeah, that's a forged Venolia Slug, and the CR is probably a bit higher than 10:1... Probably closer to 13.5-14:1 given the shape of the dome it was used in closed-chamber welded heads....like a welded E88, N42 or early E31---L's take Compression. Quote Link to comment Share on other sites More sharing options...
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