17 replies to this topic

[Spider]

Just reading Shooter's comments there on the Merc engine, a friend and colleague routinely does a fair bit of the more difficult machining work on 'vintage' F1 engines, a few years back, he had the Hart engine from Allan Jone's Turbo F1 car. That had 45⁰ seats in it, but then it ran cira 45 PSI boost pressure too. To avoid head gasket issues, the head and block were cast one piece (and that's why this particular engine landed in his bench)

 

 

I can see where 'flater' valve seat angles can help with lower valve lifts, but then, I think much could be gained from observations and tests on the flow bench. Have you done any plots Phil ?

[Turbo Phil]

Yes. Up to about .300” there’s a substantial gain in flow over a 45deg seat.
It’s all in Vizards book, but I like to test these things myself so I’ve done some flowbench work to prove it to myself.

Phil.

[Pigeonto]

Hardly a high performance application !! but I work on small air cooled single cylinder engines.

Briggs And Stratton engines, up 'til they went to OHV used 30 deg inlet and 45deg exhaust. If valve seal at higher temperatures is an issue, that may be worth a try Phil