Why does Ferrari still use cambelts?

They don't. F430 uses chains.

There is nothing wrong with belts. Honda, Nissan, Toyota, in fact MOST brands of OHC engines use belts.

They are light and strong and quiet.

Birdman

 

All Ferrari models up to the Boxer used chains to drive the camshafts. The Boxer was the first to use rubber belts and the reason given was, noise reduction and the simplification of the engine castings (no need for enclosed oil lubrication areas).

 

You would think so, but not neccesarily the case. More so for engine noise/cabin noise reduction. Not many auto manufactures' use timing chains these days. Timing belts are more quiet. Although, some still use timing chains. Timing belts are also more effecient than timing chains apparently.

 

From an engineering point of view, belts are way better. From a practical point of view, chains are better. Perhaps if Ferrari belts were guaranteed for 50k miles, they'd still be using them. I changed my Accord belt at 60k miles but of course it's apples and oranges. My Lotus chain is still running strong after 34 years.

Ken

 

I have been told that "back in the old days" belts provided a greater degree of accuracy than chains, which is critical because FCars are high reving and have a tight valve tolarerance.

 

I really dont know why no one else seems to aknowledge this, but the belt drive was a performance part more than anything else. Imagine the weight of a chain long enough to encircle all four cams. Ferrari generally ran a 3 row chain, so between chain, and heavy steel sprockets, you get quite a chunk of weight. The weight of the belt drive is almost zero in comaprison. People spend thousands trying to remove rotating and reciprocating weight from an engine, yet in this case a monster amount is already gone. It seems sometimes like some people want the best of both worlds. Ultra high performance with zero maintainance.

 

When the cars were 230 HP it was a huge difference to reduce the rotating weight and no one knew what a maintainence headache they would become. Today, with 5-600 HP, there is much less need for a fragile belt system and the chains make a lot more sense IMHO.

Ken

 

chains will transmit crank harmonics to the camshaft, chains will stretch at high RPM causing a retard in timing. chains are heavy, and yes they do break. belts are lighter quieter and dampen the crank harmonics as well as resist the tendency to stretch. shorter service life though.

big block motors use chains due to torque, only now with newer technology can some of the belts handle the high torque from large displacement motors. most of the big block engines use chains or gears, few use belts. there are aftermarket belt systems for the older motors as well.

the oddest use of a chain is in the ford modular motor. it has DHOC heads. there is a single chain running up to the intake cam then a small chain linking the two cams together. it works and the bean counters i'm sure were happy, the enthusiast who race them are not.

 

The F50 uses a chain as does the new F430. What has me scratching my head is, why they don't just scrap the whole belt/chain deal and go with cam gears like they use in F1?

 

$$$$ Gears are the most costly system, but for the prices these cars are, it's a legitmate question. Also, wouldn't gears be heavier than belts?

Ken

 

Noise! those buggers are NOISY! even helical cut gears are make noise. in F1 it isn't a concern but for the mojority of street drivers who want to hear their radio and hold a conversation it's a big deal. ofcourse us who own the older models already have noisy cars so it's no big loss.

gears make a high pitched whine that can be irratating to some, it's a harmonic frequency that's matched to the speed of the gear. there's a science to that also as the frequency can literally destroy a gear at speed, 'shatter'. talk about engine damage!

 

Oh I'm well aware that they are noisy. When I was a kid, the friend of the guy that live on the next block had a Pontiac GTO with gear drive. You could hear that thing coming from two blocks away. It did sound pretty sweet though. I'm pretty sure with todays technology they could find a way to keep things quiet.

 

helical cut gears reduce noise, the noise is the result of the gear lash. and that can not be avoided as the gears need to make contact. belts have lash also but the materail composition and tooth profile will affect how loud or quiet the belt is. on gears the materail is hardend steel and the tensile streangth gives it the charactristic whine. worm gears are the closest thing to nearly silent operation, however space packaging make that arangement impossible as each transition is 90* from the next.

go real high tech and ditch camshafts alltogether and use a computor controlled pnuematic or electric valve operation. no direct tie to the crank and complety adjustable. imagine, no need to ever change belts, chains, shims or cams. we have the technology, let's get it mainstream.

 

rubber timing gear.... cheap.

 

i don't understand? belts are very technologicaly advanced, also the parts that make up the system are costly compared to chain driven ones.

 

In the late 60's. Pontiac used a teflon coated gear on the crank to reduce chain noise. Unfortunately, the teflon tended come off and plug up the oil pickup. Don't ask how I know this, it is an unpleasant subject.

Dave

 

I like the way your thinking, even better: no valves and direct injection two stroke gasoline motor with a flat crank. Think of the revs!

I've have a gear driven camshaft on a small block Chevrolet and it sounds great. The vendor sold two setups: "noisy" a little extra lash between the gears and "quiet" minimal lash. It sounds great and has never had any problems (quiet setup).

As stated above, with high torque motors the weight of the camshaft drive is not a big factor. Most of the time street motors have a big 20 pound flywheel to ease shifting.

Worm gear drive sounds like a viable option. Minimal rotational mass and noise. It would be feasable to drive two shafts from the crank shaft and from there two camshafts.

 

They don't. Just run them till they strip off the teeth and you can rebuild whats left and start over. You like chains? You should see what they can do when they wind themselves up around the crankshaft.

 

chain driven cam systems are way way way more reliable , longlasting and
maintenance 'free' when compared to ANY rubber belt system.

switching to rubber belt is actually cheaper (to manufacture) for the maker
and easier to assemble , than compared to chain driven systems.
.

 

Uh..... isn't the 612 the only Ferrari that is still using belts?

 

This is the problem. Mr. Ferrari tried to give us the fruits of his labour. He gave us high performance Formula One and Grand Prix engine technology, yet many of you seem to want Honda reliability and grocery getter maintainance. You dont always put the most reliable, longest lasting and maintainance free parts on a race car. You make sacrifices for performance. You take educated risks. I sometimes think many of you would be just as happy with a small block Chevy motor as this lowly 308 POS.

I also own a 1983 Mercedes 380 roadster. It has a V8 with chain driven cams. I would hazard to guess that chain and all those steel sprockets are well over 20 pounds. The original was a single row chain, and many were replaced under warrantee. Now they are dual chain. Cost to convert it was over $4000. Take it to the dealer every 100K miles for replacement, still spend another $4000. When it breaks it will do all the usual valve damage, only because they go stright up and down they will probably hole the pistons. Might break a cam. Then probably the chain will wind around the crank and split the case apart. 50/50 deal that. Cheaper then to find a yard motor for $4000.

I just swapped belts in my 308 in an afternoon. Its not that hard or big a deal and its certainly not that expensive considering the damage a stripped one could do.

 

hi.

you've got some valid points there.

its just that Honda (to use the maker for which you're using as an example)
are able to squeeze very reliable horses from very reliable NA engines. These
engine are tolerant to tuning , abuse and neglect.

Ferrari , on the other hand , is also able to squeeze horses , but at very
much increased cost and complexity. These engine , on the other hand,
are VERY intolerant to abuse and neglect. As for tuning them ... haha.

so, I don't think that Mr Ferrari was doing anything really great. The really
great bit was done by Pininfarina. imho , of course.

you guys need to be a little less enamoured by the ferrari engine mystique.

cheers and good discussion.

.

 

Honda isn't making anything that is "squeezing horses" anywhere near the level that Ferrari is, unless you are comparing the new Hondas to the 30 year old 308.

Compare Ferrari to any other car within the same production year and Ferrari is always at the height of performance.

Birdman