F1 Cylinder Head Design and Pneumatics, a closer look

[riff_raff]

The most likely benefit of using slightly canted valves was the additional space created for the pneumatic springs and the spark plug body. I don't think the slight amount of valve cant would help gas flows much.

[gruntguru]

As it happens, the canting is mainly about gas flow (reduced bore shrouding).

[Brian.G]

As it happens, the canting is mainly about gas flow (reduced bore shrouding).

Thought so - thats generally the top reason, with packaging second,

[riff_raff]

Do you really think canting the intake valves a few degrees from normal will improve gas flow by reducing "bore shrouding"? The intake gas flow is primarily determined by the orifice created by the gap between the valve face and seat, and a modest change in the angle of the orifice would make no difference.

[Brian.G]

Do you really think canting the intake valves a few degrees from normal will improve gas flow by reducing "bore shrouding"? The intake gas flow is primarily determined by the orifice created by the gap between the valve face and seat, and a modest change in the angle of the orifice would make no difference.

I do think it has an effect yes. Various flow pdfs that I looked at years ago confirms it also. Its a small difference but there at the curtain area all the same.

Brian,

[gruntguru]

Think in terms of aiming the port more towards the centre of the bore. The flow increase might only be slight but 0.5% of 700 hp is 3.5 hp.

[Brian Coat]

I also think the compound valve and is for combustion efficiency (at very high B/S and very high rpm).

As CR is increased (often not knock limited at ultra high rpm), the chamber gets very flattened, with a corresponding detrimental effect on combustion. Compound valve angle provides some relief to this by distributing the compression volume better.

[gruntguru]

Closer to a true hemi.

[Brian Coat]

"closer to 'true' hemi".

Er, I suppose so, geometrically; but not in the sense that a hemi is any kind of ideal, or 'true North' for an F1 engine!

[gruntguru]

So what would you consider ideal - purely from a combustion perspective?

[Brian Coat]

If I'm being honest, I don't think there is an ideal F1 combustion chamber. I think all you have is the latest best one you designed and tested, given the rules prevailing at the time.

But a quick back-of-envelope calc shows that any true hemisphere can only achieve a CR *much* lower than that used in F1, assuming the B/S ratios used (and now mandated) in F1 and it is this fact which led to my remark.

[hardingfv32]

Does CR have a higher priority than say intake flow swirl properties?

Brian

[Brian.G]

If I'm being honest, I don't think there is an ideal F1 combustion chamber. I think all you have is the latest best one you designed and tested, given the rules prevailing at the time.

But a quick back-of-envelope calc shows that any true hemisphere can only achieve a CR *much* lower than that used in F1, assuming the B/S ratios used (and now mandated) in F1 and it is this fact which led to my remark.

I would tend to agree here Brian,

Brian,

[gruntguru]

Me too, although my original point was about hemi chamber shape and combustion efficiency. I am fully aware of the compromises required to obtain appropriate CR and B/S.

[Brian.G]

Just spotted this was posted a year ago to the day, what a fast year

Since sectioned the head in two other places - will host images this evening,

Brian,