F430 has chains not belts?

All F1 engines use gear driven valve gear,and camshafts are still in there the valve lift is on the 17mm mark,valve to piston contact is very close indeed,

Dale.

 

I'm surprised that it took so many posts to bring this out. F1 cars have been using gear drive for quite some time and I remember that when the F50 came out, it had a re-worked 1990 F1 engine that swapped gears for chain drive. Reason being that gear drive is VERY loud.

The pneumatic valves in F1 engines were used because the increasing engine speeds hit a wall at about 14K revs. It was simply impossible to put a big enough spring to handle the revs without valve float. The solution (I believe first used by Renault) was to go to pneumatic filled accorian style springs. Air has a cubic spring rate and has removed valve float from the equation.

The next big thing is going to be solenoid actuated valves. No more cams or cam drive assemblies. The potential advantages are HUGE:

- No cam and drive mass to turn.
- Infinately adjustable intake and exhaust timing on each individual cylinder.

It is not that far off as this system is already been tested for several years. Reliability at 19K rpm for 2+ hours is still in the works.

Back to production cars, another reason belts are used in favour of chains is that belt systems cost much less to produce than chain ones. Lower the production cost of the car and screw the customer come service time.

 

Gear driven cams huh? Like the pushrod V8 upgrades to eliminate the chain you can do? That make perfect sense.

My guess it that they've gone to chains because they allow them to rev the engine higher (with better reliability than belts) and the increase in HP they get out of the extra revs offsets the HP they loose by using chains. It's a bit of a compromise. You trade a little in one area to gain in another. I'd love to hear that engine with gear driven cams. Or the F50 would do me just fine!

And yes it was Renault that introduced the pneumatic valves to Formula 1. That was over ten years ago.

 

Advantage for belts over chains: Belts are more quiet and can run without lubrication, a simple plastic cover, or alloy cover in case of Ferraris, will do. Chains have to run through an oil bath in a sealed environment, like inside the engine. This makes the engine case bigger and heavier.

 

Im sure renault have run the solenoid actuated valve system on test beds,the big disadvantage with it is it puts to much height and weight on top of the engine,until this is overcome pneumatic is here to stay for now,

Dale.

 

Most of the japanese cars nowadays use Belts, most Euro cars seem to go the chain route.

I know that belt driven engines recommend a change around 100-120,000 miles where as chains are 'supposed' to last the life of the car assuming you lubricate the chain correctly.

Another advantage of belts is that it's lighter so less rotational inertia.

 

as folks stated before air pressure only replaces the spring (see attached picture) - a.) pneumatic keeps pressure constant while springs vary with lift b.) reduced mass, i.e. higher RPMs c.) springs limit lift
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Excellent diagram. Thanks!

 

The cost of belt changes every few years would never come close to the costs associated in changing to a chain drive.

The worry of belt breakages is so hugely blown out of proportion. Cam belt breakages happen only when the belt is so terribly neglected that it fails. This can be due to age or mileage. In the case of Ferraris, this happens very rarely and usually to cars with low mileage. The part of the story that is always left out is how the belts were 15+ years old despite the fact that the car only had 2000 miles. The belts on a Ferrari are no cheaper or better than say a Honda S2000 or Integra Type R. In these cars the belts are fine for 60K as they are in a Ferrari. Ferrari's service schedule of 30K is a product of 2 factors:

1. They realize that 30K takes a long time for most Ferrari owners to achieve (therefore making it a time interval rather than a mileage one)

2. Belt changes are cheap insurance when an engine costs as much as it does to re-build.

Provided the car is driven regularly, then a 5 year 30K service schedule is WELL on the safe side.

With all the wonderful things there are to worry about, belts should not be one of them

 

Very well put, Robert Calisi!
Very true, very helpful, and worth re-reading!

 

Belt changes on new Ferraris are recommended at 3 year interval. Of course this recommendation maybe motivated by other factors... Most early 360 productions have had to go through a belt change even though the mileage certainly for most of them are significantly below 20K.

 

So now our V-8 Ferrari's will have FOUR distributors instead of two!!! Ah, points adjustment madness I say....aahhhhhh