a side note on alum heads,need to use commetic head gaskets and the thermal efficiency of the heads is like loosing 2 points of compression, just something to research,
Thankfully neither of those are necessarily true from what I've found recently. 440Source sells single-layer composite head gaskets with a Teflon coating for use with their aluminum heads (not multi-layer steel type although they are some of the best, I have Cometics in the 360 in my Duster). And on the Engine Masters show they proved the "aluminum heads compression loss" to be a myth; took a built BBC and dyno'd it with iron heads, then swapped on a set of aluminum heads with the exact same specs, hardware, compression ratio and changing no other parts... the aluminums actually made more power across the board than the irons with everything else equal. Aluminum heads are more detonation resistant because the fast heat transfer doesn't let the surface get as hot as iron and the finish is usually a lot smoother which also reduces hot-spots for preignition. I think over the years people just associated that with a loss of thermal efficiency which simply isn't true; above about 2000 RPM the mixture is burned and exhausted too fast for any real heat transfer to occur on a level that would affect power.
I'll have to do a bit more math but looking on the UEM/KB site they now sell 3 different hyper pistons; one zero-deck flat top and then two flat-tops with reduced compression height but a quench pad that raises up from the piston head. According to their approximate compression chart with 80cc heads they would put me around 9.7:1 which would be right around what I want. If this was going in a car or street-rod type truck I'd be fine going as high as 11:1 but thinking about how this engine will be pulling 10,000+ lbs (truck+trailer combined) up steep hills I'm afraid the thermal loading will be too high and it will eventually either overheat or start to ping which is the LAST thing you want happening pulling up a steep grade on the freeway. Maybe aside from losing fuel supply lol, it can be nerve-wracking especially in heavy traffic.
