F1 Pneumatic Valve Spring, a closer look

[ringo]

He doesn't need a CNC machine to do that part though.
Just good old machining skills.

[MrPotatoHead]

He doesn't need a CNC machine to do that part though.
Just good old machining skills.

I've seen many an impressive manual machined part for sure.
But I'm a CNC guy myself. Most of the stuff I'm involved in would be impossible on a manual machine

On topic - I've always wanted to make a pneumatic valve setup on a street car. Maybe someday when I have the time this thread will motivate me.

[63l8qrrfy6]

There are very good reasons why there's no pneumatic valves in road cars yet.

Seals wear fast, they need a pneumatic bottle and/or a compressor, the oil purge system is a black art, valve rotation is very poor and highish lift, large included angle valves can drop and lock when pressure is lost (as in when the car has sat for a while).

Ah yeah and calculating the required pressure is another pain - too high and the they eat up more power than a spring, too low and they float.

[Brian.G]

He doesn't need a CNC machine to do that part though.
Just good old machining skills.

I started machining about 20yrs ago on a lathe and mill with about 3mm backlash that turned out parts accurate to 3 thou so a cnc these days is just a nice commodity to have

Brian,

[MrPotatoHead]

There are very good reasons why there's no pneumatic valves in road cars yet.

Seals wear fast, they need a pneumatic bottle and/or a compressor, the oil purge system is a black art, valve rotation is very poor and highish lift, large included angle valves can drop and lock when pressure is lost (as in when the car has sat for a while).

Ah yeah and calculating the required pressure is another pain - too high and the they eat up more power than a spring, too low and they float.

The seal problem is solvable using available parts. Pneumatic bottle / Tank is obvious.
As far as the rest - if I ever did pursue such a project I would develop the valvetrain using FEA and then test on a Spintron. But that's a big if, I doubt I'll ever have the time to be honest.

Besides when I say "street car" I'm not talking about a vehicle that lasts 250,000 miles I'm talking about one of my project cars that typically see less than 10,000 miles between rebuilds.

[gruntguru]

The benefits would be pretty marginal - even on high revving (>12,000 rpm) engines.

[MrPotatoHead]

The benefits would be pretty marginal - even on high revving (>12,000 rpm) engines.

I don't think I would say the benefits are marginal... not when getting beyond 12,000 rpm with conventional valves can be very difficult to keep the valve under control.

[gruntguru]

Just saying - on a race engine 5% is a worthwhile benefit, for the street you just get a 5% bigger engine.

[Brian.G]

I think if the valvetrain is starting to be one of your concerns then you will have crossed many hurdles before that point with other parts and spent a LOT of cash prior. Do/Don't some of the bike engines run springs upto 14k?

Brian,

[MrPotatoHead]

Yeah it' really one of those projects that I'd like to do for the sake of doing it.

On any existing street car engine that I would likely use the stroke length will limit things more than likely.

[gruntguru]

I think if the valvetrain is starting to be one of your concerns then you will have crossed many hurdles before that point with other parts and spent a LOT of cash prior. Do/Don't some of the bike engines run springs upto 14k?
Brian,

and beyond - I know Yamaha R6 was turning 17k years ago. Pretty small/light valves though.

[MrPotatoHead]

Part of the reason engines like the R6 can achieve such a high rev limit is because of the very short stroke - around 42mm.
The other reason is the valves themselves are so small. This means the inertia being moved is a lot lower but more importantly the valve lift is physically a lot lower.
There is a magic sweet spot for valve lift as a percentage of valve diameter. Because of this the smaller the valve the smaller the lift and the easier the job of the valve spring. Apples vs Oranges so to speak.

[godlameroso]

Then the answer is obvious weld 4 bike engines together on a custom crank and use valve springs.

[MrPotatoHead]

Then the answer is obvious weld 4 bike engines together on a custom crank and use valve springs.

Haha genius.
Of course you can already buy a V8 that is done using 2 motorcycle 4 cylinders and a custom crank and crankcase.

[PhillipM]

Then the answer is obvious weld 4 bike engines together on a custom crank and use valve springs.

Save you the hassle, here's one that was made earlier:

https://www.youtube.com/watch?v=66CKSzyKZno

(Yes, that's 4 x R6 engines on a common crank)