26 replies to this topic

[ViMaMo]

I was just curious if F1 engines boasted very complex valve train systems like the road cars. BMW has the credit for Double VANOS. Honda for VTEC. Toyota for VVTi. Is it possible for an F1 engine to use those complex systems ? The big hurdle is obviously the very high RPMs. Road cars do a max of 9000 RPM. Anyone has any clues?

[scarbs]

No F1 engines use simple finger follower valve trains with fixed cam timing.

[ViMaMo]

is it :

1. no, F1 engine use simple finger follower valve trains with fixed cam timing
2. no F1 engine use simple finger follower valve trains with fixed cam timing

sorry, i'm confused

[xflow7]

My guess is "No. F1 engines use...."

Given that F1 motors are all out race engines that will in general be kept in their powerband, small driveability improvements in the rev range of interest would be far outweighed (no pun intended) by the disadvantage of substantial additional weight and complexity.

[J. Edlund]

F1 engines use four cams, finger followers, 4 valves/cyl, pneumatical valve springs and titanium valves. The timing is fixed and the cams are gear driven.

[ViMaMo]

Originally posted by xflow7
My guess is "No. F1 engines use...."

Given that F1 motors are all out race engines that will in general be kept in their powerband, small driveability improvements in the rev range of interest would be far outweighed (no pun intended) by the disadvantage of substantial additional weight and complexity.

since the time for induction gets shorter and shorter at higher rpms, i suppose these systems not too effective ? renault's solenoid valve system was a sort of variable valvetain system.

i wonder how much a simple system would add to the overall weight. extra cams+springs 4*10. plus the hydraulic system.

[mrman_3k]

Does anyone have a picture of what the gearset looks like that drives the cams?

[jgm]

There are some detailed drawings and photographs of the details of the 2000 Ferrari engine in Peter Wright's new book about about that car.

[McGuire]

Current variable valve/cam timing mechanisms are not sufficiently stable or positive at the ultra-high rpm achieved by F1 engines. A few degrees of timing scatter will easily negate the potential advantages.

Also: The benefit of these systems in passenger cars is not in the widening of the torque curve per se, but in the increased driveability and tractability they offer to the consumer. Less shifting and increased flexibility is important there, while in racing only lap times matter...which is a rather different thing.

[Patrice L'Rodent]

Don't forget, in road car systems, they advance the inlet cam to permit EGR.
Personally, I think 95% of the reason for VVT on road engines is for emissions reduction.
PDR

[J. Edlund]

Also, in an F1 engine the valves can follow the piston with a distance of .5mm during when the piston is close to the head, this means that the valve movement must be very accurate. Alter the timing a few degrees and they may hit eachother.

Variable valve systems may also increase friction, and at the speeds F1 engines use a small increase can cause the power to drop quite a bit. The added weight is also added on the place were weight savings is most important; high up on the engine.

The use of solenoids to actuate the valves would today be impossible.

Another use of these variable valve systems is to reduce pumping losses at part throttle for a lower fuel consumption as well as lower exhaust emissions, and those aren't that important for a racing engine.

[Keith Young]

it would be even harder for them to bring in vvt now that the engine rule is in effect. Perhaps one of the teams out of the top 4 would be better off doing it as they have little to lose.

[desmo]

VVL might be another story, someone sent me a spy photo a year or two back of the BMW F1 engine- unfortunately lost when my hard drive went TU- that seemed to show an absence conventional throttles. Anyone care to speculate on the feasibility of using VVL in lieu of conventional throttling for F1 applications?

[ViMaMo]

i'm pretty lame when it comes to these stuff. anyways i'm throwing in my ideas.

a light engine can only undertake such additions. 2 extra cams for each cylinder plus the hyraulic system. or a 3D profile that varies along the length of the cam lobe like in ferrari road cars.

1. is it possible that the engine's vee could be increased to lower the CG to negate the weight added.
2. a higher vee might reduce the max rpm, but could the engine develope better power and torque in the enlarged power band?
3. traction control possible with such mechanism ? lower lift at lower gears.

[Dynojet]

No F1 engines use simple finger follower valve trains with fixed cam timing.

Altough I don't have seen any real picture of a valvetrain of a nowadays F-1 engine, I don't belive it come to have finger followers.
If you have enough space in the camshaft to put ten lobes (and there is), there is no point in using followers. It just become a weak link and more mass in the system.

My car (it is not a hi-reving) has only the camshaft acting over mechanical lifters, and is a very stable and robust system. It can securely run 8000 RPM (if the camshaft duration allowed).

I remember seeing a picture of the gas spring anywere here in the forum, if someone could find...

[Halfwitt]

What fingers allow you to do is reduce mass by not having to use a massive tappet follower (bucket). To get high enough lift velocities without fingers, you would need to run large diameter followers and massive cams to get the lift. Fingers also allow you to run a smaller diameter camshaft. I think this system has been used on most F1 engines for a few years now.

[McGuire]

Originally posted by Halfwitt
What fingers allow you to do is reduce mass by not having to use a massive tappet follower (bucket). To get high enough lift velocities without fingers, you would need to run large diameter followers and massive cams to get the lift. Fingers also allow you to run a smaller diameter camshaft. I think this system has been used on most F1 engines for a few years now.

Exactly right. Bucket or mushroom followers now seem to have run their course -- due to the limitations of the geometry, the original Chevy IRL engine (the one displaced by the Chevworth) has been obsoleted by its use of bucket followers. Also, the finger followers allow some current F1 engines to have valves disposed in two planes (valve pairs splayed 3 to 6 degrees to each other in side elevation).

[J. Edlund]

BMW:s variable valve lift system isn't even used on their high power production engines as it's said to cause a lot of extra friction at high engine speeds. So the question is if this friction problem can be solved.

A larger V angle introduce several problems:
- Balance. This usually cause the maximum rpm to drop.
- Exhaust manifolds. It's more difficult to fit large radius manifolds which can reduce VE.
- Inlet tuning.

[ZoRG]

I think they are problably runnin roller followers running 2 valves off one cam lobe, with a ratio higher than 1.5:1.
Something like this:



I cannot see them running without a follower, there are many benefits to doing this instead of the bucket system.

As for not using throttles, and using valve lift to achieve the same settings, it works on the BMW road car, but I doubt that you will want something that complicated at 19000rpm....

[Halfwitt]

I think that the picture posted by J.Edlund further up is a pretty close approximation of the systems used for racing, i.e. 1 finger and 1 cam lobe per valve without roller followers.

[ZoRG]

I doubt it, if they want to cut friction, they will go with a rollar system, also due to the high lift roller systems work much better, I know that pic, its from the Del West website, I just don't think there are any reasons not to use a rollar system, as for the joining of the two, you save alot of weight by going that route as oppose to a seperate system.

[McGuire]

Perhaps surprisngly, most F1 engines (at least the ones I have seen illustrated) do not seem to use rollers on the followers. For example, the 2000 itieration of the Ferrari in Peter Wright's latest book uses plain followers.

[ZoRG]

Maybe the rules don't allow roller rockers ? I just cannot believe that a sliding follower can outperform a roller follower.

[J. Edlund]

I don't believe a roller follower will be light enough.

Someone working with coatings claimed in some technical magazine that they use DLC on the finger followers used in F1, and with a conventional coating, a think it was some sort of chrome the followers wouldn't have lasted longer than 10 minutes. So I think that clears it out that F1 engines are using simple finger followers with DLC coating for low friction and a hard surface.

Earlier bucket type followers was used.

[marion5drsn]

Quote from J. Edlund

F1 engines use four cams, finger followers, 4 valves/cyl. pneumatic valve springs and titanium valves. The timing is fixed and the cams are gear driven.

This sentence implies that all F1 Engines without exception are thus arranged, as there are no qualifications to the statement. I find it difficult to believe that Toyota use finger followers as all their production engines are bucket type. It would seem that they have the whole bucket situation down to a fine art of engineering and production capabilities. The only thing that might prevent them from using this are the gas springs. Doesn’t Toyota’s entire Japanese engineering department back up their F1 effort?

M. L. Anderson

[finncrazy]

True... F1 cars use mechanical valve actuation using a kevlar belt for timing. Only the return is pneumatic. If i am not wrong, i think the pneumatic system is activated by a pressurised nitrogen tank in the car.

[desmo]

Originally posted by finncrazy
True... F1 cars use mechanical valve actuationusing a kevlar belt for timing. Only the return is pneumatic. If i am not wrong, i think the pneumatic system is activated by a pressurised nitrogen tank in the car.

All the cam drive arrangements in F1 are gear trains.