Cars Running on Timing Chains instead of Timing Belts

[konfab]

A friend's Audi A4 recently snapped its timing chain. A lot more expensive to fix when it does go.

True, given the chain would basically explode.

However the damage shouldn't be any better or worse than a timing belt. Only thing is it is more difficult to replace.

 

[boxerulez]

True, given the chain would basically explode.

However the damage shouldn't be any better or worse than a timing belt. Only thing is it is more difficult to replace.

the chain will also damage the pulley on the crnk and camshaft. however some cylinder heads have enough clearance t not bend valves when this happens.

If you are lucky enough.

 

[Fazda]

Manufacturers switched from chains to belts about 30 years ago, and belts are great as far as being quiet....however, belts also need to be replaced at between 60 and 100 000 k's and that is expensive.

Recently, chain development has improved in vast amounts, so that many manufacturers are moving back to chains and they should be fine for the life of the engine.

Definitely the way to go, but if you have a belt, as I do.......it has to be changed regularly...

 

[Magnum]

Manufacturers switched from chains to belts about 30 years ago, and belts are great as far as being quiet....however, belts also need to be replaced at between 60 and 100 000 k's and that is expensive.

Recently, chain development has improved in vast amounts, so that many manufacturers are moving back to chains and they should be fine for the life of the engine.

Definitely the way to go, but if you have a belt, as I do.......it has to be changed regularly...

Isn't your belt worn out already?

 

[Fazda]

Isn't your belt worn out already?

Yup - changed last year.

 

[Magnum]

No that was your car's belt...

 

[Fazda]

No that was your car's belt...

Sorry.

No, I run on a chain.

 

[Magnum]

Good! Hope to have you around for a while still.

 

[Fazda]

Good! Hope to have you around for a while still.

Thanks!

 

[Magnum]

Thanks!

I still want to know. Efficiency. Chain vs belt. single cam vs DOHC vs TWINCAM.
two cams. double the friction, more moving parts more power loss and reduced economy.

 

[Fazda]

I still want to know. Efficiency. Chain vs belt. single cam vs DOHC vs TWINCAM.
two cams. double the friction, more moving parts more power loss and reduced economy.

As far as I have been told ( when we switched from belt to chain in Subaru) - chain is first choice, every time, particularly with the latest technology. I THINK that DOHC is more efficient than SOHC ->better economy as well.

Twincam and DOHC is the same thing.

 

[Magnum]

I always get in a spat over DOHC and TWINCAM. I feel DOHC is two cams driven by a single pulley. Where TWIN is two exact cams each with its own drive.

Also SOHC engines were under developed to be cheaper, lower performance variant to the flagship Multicam.
In theory should also have less power and fuel economy as a result.

You only need 7KW to travel down a road at a constant speed. The engine that produces that with fewer parts than the flagship and still producing the same amount of power and torque vs the fuel used must be more fuel efficient.

 

[Fazda]

I always get in a spat over DOHC and TWINCAM. I feel DOHC is two cams driven by a single pulley. Where TWIN is two exact cams each with its own drive.

No, it's the same thing - semantics to try and say anything else.

 

[Magnum]

Everyone views them in the same light. To me they are different in working and in looks and must therefor be completely different. We are all unique and no one just accepts my views and theory's.

I have stopped trying to explain my findings and thoughts to the inert masses and focused on what matters to me.

 

[Colin62]

I always get in a spat over DOHC and TWINCAM. I feel DOHC is two cams driven by a single pulley. Where TWIN is two exact cams each with its own drive.

Perhaps you can give us an example of two cams driven by a single pulley? And tell us how one pulley drives two cams?

 

[Fazda]

Magnum - do you not realise that Twin exact cams are exactly the same as two cams driven by a pulley?

How do you think cams turn in each car? And if the cams weren't the same, the car wouldn't run - basic engineering!

 

[Username:]

Perhaps you can give us an example of two cams driven by a single pulley? And tell us how one pulley drives two cams?

Toyota 4afe vs 4age engines
Both 1600cc, both 16v

One has twincams the other has two ;-)

 

[Fazda]

Toyota 4afe vs 4age engines
Both 1600cc, both 16v

One has twincams the other has two ;-)

Oh please! They are both DOHC motors - the only difference is the spacing of the cams on the head.

1+1=2 or 2 = 1+1 whatever floats your boat.

 

[boxerulez]

Toyota 4afe vs 4age engines
Both 1600cc, both 16v

One has twincams the other has two ;-)

Twincam : Both Intake and Exhaust cam runs in the exact same direction.

DOHC includes but is not limited to twincam. DOHC cars can have PulleyGear running the 2 cams inside the valve cover.

In this case the 2 camshafts will run in opposite directions and cams will be cut accordingly.

All that only applies to belt driven cams.

Chaindrive DOHC vehicles are all "twincam".

 

[Beachless]

The only thing I can possibly think of is that a twin cam engine has identical inlet and outlet cams whereas a dohc does not. But all this running in oposite direction stuff makes my head hurt.