Thread: What makes some 4.6 V8s high compression?

after we built it up from a 4.0L cross bolted block with 3.5 hi comp heads, a stage one cam from bruce davis, the original inlet manifold with the carbys, it wouldn't run on anything but premium without pinging.
since then i put one of those fuelstar catalysts on, nowi can run on uleaded in an emergency, but it's best on 95 octane. recently put electronic ign on it and it's better again.

Originally Posted by p38arover

42D LC 4.0
44D HC 4.0
46D HC 4.6
48D LC 4.6
That's factory fitment. Then there are the replacement engines.....

9.35:1 is HC

Just checked, I have a 46D with a slightly dished piston and there are some milled cut outs for valve clearance. Can take a pic, would like to run this over 10:1 for LPG only set up. If flat topped pistons won't belt the valves (or the have milled cut outs like mine) then this would be the best way to achieve this. Not a fan of milling heads.....

Sorry to pinch the thread, but it's all good info!

Thanks!

Originally Posted by p38arover

I was talking to a bloke this week about this. He said one can use forklift cylinders.

This guy aparently makes them to look just like standard 20L cans. Can make them into any shape aparently. Makes me want to go out and spend $3000 on an LPG conversion just to have the cans!! Not sure how he connects to the main tank though, adaptor hose to the nozzle must be expensive....
Still waiting on my customer finding the contact number.