TwinCam valve vs Minardi V10 valve

[SADLOTUS]

A friend recently gave me a Minardi F1 valve as a pressy, he'd seen my TwinCam one on the shelf and thought they'd make good bedfellows.
Surprising - or not - how similar they are and yet so different (really Paul?)
The Minardi valve is half the weight - 30g (on the kitcken scales)
The Lotus valve - 60g (again, scientifically weighed on the kitcken scales)
The diameter's are almost exactly the same (er, not sure if the TwinCam valve is inlet or exhaust, but certainly from a BigValve.
And, as you might be able to see, the Minardi is about 2cms taller and the stem is half the diameter.
Not really sure what I'm trying to show here, 'Look how far F1 technology has come - or not - in 40 odd years?
Interesting. Well, for me anyway. Slightly.

[rgh0]

What drives the changes is a good question if you are into cylinder head design optimisation .

Tghe Twin cam valve head diameter is around the same size as modern 4 or 5 valve heads as you dont need bigger valves to get the higher volumetric efficiency they achieve they just have more of them.

Stem is smaller diameter to minimize flow obstruction in the port. This results in smaller wearing surface area compared to the bigger stem on a twink. This is OK in the Minardi due to its short design life, better materials and better oils than in the twin cam design days. The valve guide is also probably longer increasing the bearing area to compensate for the smaller diameter

The Minardi stem is longer compared to the twink to allow for longer valves guide (see above) and also to allow space for longer valve spring assembly and higher lift.

End result of all the above results in lower valve weight compared to a twink valve which makes high revs and radical modern racing cam profiles easier to achieve.

The short stem length and limited space for the guide and valve spring is the biggest challenge in designing a twink racing engine with a high lift cam as the possible increase in stem length governed by and very limited by the head casting distancee between the combustion chamber and cam centre line

cheers
Rohan

[el-saturn]

you evidently know what you're talking about - some of the finest valves (F1 and so forth) are hollow and I think BMW started making 'em! cheers sandy j. S3 DHC - 1700 cc and very high lift! --- ANYBODY NEED A NEWLY REBUILT TC ENGINE - ABOUT 1000MILES SINCE TOTAL REBUILD!

[GrUmPyBoDgEr]

To compare valves from 2 valve & 4 valve engines opens up lots of possibilities.

The 4 valve design permits large valve port openings but with a pair of rather than just one large valve.
Larger valves have a larger mass & subsequently stronger valve springs are needed to close those valves indeed quite often a pair of concentric springs as in the Twinc are used.

Modern 4 valve engines can safely rev' fairly high & have just one valve spring per valve; those valves having less mass.
The lower mass also means that the valve stem diameter can be reduced without risk of it breaking as well of course the improved flow mentioned above by Rohan etc.

Modern BMW production engines utilise 5mm diameter valve stems in comparison to the Twinc's 5/16" stems.

Cheers
John

[peterexpart]

Just an observation, you all need to get out more !!!

[GrUmPyBoDgEr]

Excuse me Sir!

You seem to have plenty of your precious time to waste in order to make supercilious comments like that!
Get out yourself!!

Love & best wishes
John

[trw99]

Just an observation, you all need to get out more !!!

Eerm, I find this thread nothing like as anorak fixated as some of mine! In fact this thread is very interesting. One valve leads to another ...

Tim

[peterexpart]

Excuse me Sir!

You seem to have plenty of your precious time to waste in order to make supercilious comments like that!
Get out yourself!!

Love & best wishes
John

I do apologise if you considered my comments to indicate a superior knowledge / intelligence that was not my intention, I was in fact looking at the board for some relief from the tedium of 120 hours getting down to the Gel Coat of my S4 ready for a repaint.
Love & best wishes to you to
Peter

[GrUmPyBoDgEr]

Excuse me Sir!

You seem to have plenty of your precious time to waste in order to make supercilious comments like that!
Get out yourself!!

Love & best wishes
John

I do apologise if you considered my comments to indicate a superior knowledge / intelligence that was not my intention, I was in fact looking at the board for some relief from the tedium of 120 hours getting down to the Gel Coat of my S4 ready for a repaint.
Love & best wishes to you to
Peter

My apologies to you to my reaction was OTT.
Yes I understand that you were not out to prove anything but when trying be humorous the phrasing needs careful choice & a couple of smileys often help slow on the uptake people such as myself

Cheers
John

[MickG]

Sorry to go off topic
Peter wrote

I was in fact looking at the board for some relief from the tedium of 120 hours getting down to the Gel Coat of my S4 ready for a repaint.

I spent two months rubbing down mine; and I mean two months not just week ends etc. Now that's tedium

Back to valves now
Regards Mick G

[CBUEB1771]

Larger valves have a larger mass & subsequently stronger valve springs are needed to close those valves indeed quite often a pair of concentric springs as in the Twinc are used.

Using two springs of different rates also helps prevent having a strong vibrational resonance in the engine's operating range. And multiple valves also help place the spark plug where you want it. I think I'll get out and about now.

[peterexpart]

Sorry to go off topic
Peter wrote

I was in fact looking at the board for some relief from the tedium of 120 hours getting down to the Gel Coat of my S4 ready for a repaint.

I spent two months rubbing down mine; and I mean two months not just week ends etc. Now that's tedium

Back to valves now
Regards Mick G

I cheated I used Removall 260 on the body, which is Gel Coat friendly !!! and had the Doors, Boot & Bonnet Soda Blasted, I do think this is one of those jobs that you wish you had never started, especially when you get down to layer 6 of 12.
Ah well must carry on, just have the Doors to cut in half now to correct the warp !!

[1964 S1]

Did the Minardi valve come out of a Cosworth engine? Is it pnuematic?

[reb53]

Did the Minardi valve come out of a Cosworth engine? Is it pnuematic?

I'd say you're right.
By 2000 wouldn't all F1 engines be using nitrogen "springs"?

Without getting all anorak about it, and I know previous comments were tongue in cheek, I quite like engineering minutiae. Especially about really expensive, top of the range, stuff.

Ralph.