Timing belt VS timing chain

[eldiabloz13]

Now my brother has a jeep cherokee and it runs a timing chain. I picked up super street febuary and there is a engine on a page that says "higher education" and its also running a chain.

Now my question is why dont us dsm'ers run chains instead of belts. I know there has to be a reason why we dont and would love to know. If there isnt a reason then why dont we switch over? It should take care of most timing belt changes and not having to worry about it breaking.

 

[99gst_racer]

Why didn't they just do gear drive?

Most of them swear by timing belts. They state that they are lighter, quieter, and absorb more engine harmonics.

 

[Elvenhome21]

SBC don't have that big of a problem with having a timing chain for several reasons
1: one cam to be driven
2. very short chain
3. stock is a silent chain, which is a decent chain as long as its replaced before it stretchs to far.
4. belt drives are nice (expensive to) on a sbc but a gear drive is just as good if not a little better for cam timing and distributor timing
5. A double roller chain solves virtually any problems with a timing chain, and WILL last for ever. Unless catostraphic failure, or manufacturing defect

the big downside of a belt is you can't run a drysump off the cam then

 

[1990talon]

Most of them swear by timing belts. They state that they are lighter, quieter, and absorb more engine harmonics.

Quieter for sure but cost for cost and preformance wise I like the gear drive but that is just me I actually am going to put a gear drive on my truck. but that is just me.

 

[JayRolla]

The new evo coming out was finally switched to a timing chain. It should be making some good power stock.

 

[PieEyedPiper]

^^^
Different engine? Or is that still on a 4g63?

 

[JayRolla]

Still the 4g63. I saw the motor on an article. They said it may have 300hp or 400hp. The evo 10

 

[PieEyedPiper]

Interesting. So does this change the front case of the 4g63 then? I read in this thread that timing chains run in a sealed compartment filled with oil, unless I got the wrong impression.
did the article give any reasons for switching to a chain?

 

[1990talon]

Still the 4g63. I saw the motor on an article. They said it may have 300hp or 400hp. The evo 10

Can you find that article for us?

 

[JayRolla]

I will look around. It was on here where I saw it I think. All I know is it said one new thing on the evo motor will be switching to a timing chain.

 

[1990talon]

Sweet if you could find it that would be cool I would like to read about it!


Brandon

 

[eldiabloz13]

i see defiant looked at the SS mag. Well it seems this post got alot hotter then what i planned. Good to see so much info in one place. Thanks for clearing everything up guys.

 

[Defiant]

I read in this thread that timing chains run in a sealed compartment filled with oil, unless I got the wrong impression.

They usually just run in engine oil, lubed by a sprayer or two.

 

[clone]

1st without a doubt chains are absolutely superior to belts.

2nd they are absolutely more expensive than belts to equip at the factory level.

3rd gears are even more expensive and the difference from gear to chain is negligible.

4th harmonics gets tuned out usually well beyond the operating environment of the engine in the design phase.

if you want to see what a timing chain can do the source for info is motorcycles which have been running chain driven DOHC for better than 30 years several hitting 17,000 rpm..... and with no replacement intervals, no reliability issues, no friction issues, they come from pre- stretched with factory tensioners and work not just fine but incredibly well, if you want reliable you go chain, if you want cheap and imprecise albeit "good enough" with a replacement schedule you go belt.

we don't see full chain driven engines is because of cost concerns.

chains run sprayed, bathing causes friction.

 

[DSM1G90]

if you want to see what a timing chain can do the source for info is motorcycles which have been running chain driven DOHC for better than 30 years several hitting 17,000 rpm's

BUT, this isn't a fair comparison due to the fact that the bike's inner chains are tons smaller due to the smaller motors (the length from head to crank is just inches compared to a regular car motor..and lighter as well) and have quite the less work distance, thus they can spin at the higher rpms. For example: imagine a motorcycle chain laid out in a circle and spin it - doesn't take much time (and effort) for the master link to go one revolution being so small. But put a car's chain laid out in the same fashion, it's gonna take more time (and effort) for that master link to make the same revolution and you can't do it all that fast either being a larger diameter.


Why we run belts instead of chains, outside of being lighter than a chain, is that the belt can take the flexing better than the chain can. And by flexing: look at the operation of the crank and cams-it doesn't roll smoothly around in circles. They are actually being pulsed around at the ignition point. The cams aren't rolling smoothly either -they're pulsed by having to push down on the valves and actually being pushed up by the valve springs.

In short, all of this pulsing has to be absorbed somewhere to run things on the smooth side. This is why, with the belt. there is the auto tensioner (or just a tensioner pulley on a spring) to help absorb all of this pulsing and the belt itself can easily flex to aid in the absorbsion.

With a chain, you got the tensioner rails on each side of the chain to absorb the snapping effect in the chain of the mechanics of the crank and cam action. But the chain can't absorb all of this like the belt can-esp those single row bicycle chains that some motor uses (why, back on that front topic of the V-8 in that Jeep, the cam chain really gets all stretched out after while and not due to a worn out tensioner block) begin to snap and shudder after awhile and they will snap unexpectedly.

The silent, multi-row chains are a lot better since smaller teeth and in many rows aid in this absorbsion, which the 4B11(T) in the new EVO's contains.

Just be happy with the belt. It's your best friend in the long run.

DSM

 

[rlacasse1]

correct me if i'm wrong. but timing chains require oil and are always under a cover in the engine. at least the ones i have seen. and it would be hard to do that to our cars.

 

[BrandonDSM]

Still the 4g63. I saw the motor on an article. They said it may have 300hp or 400hp. The evo 10

The new Evo X motor isnt a 4G63 anymore, its a 4B11 world engine used in chryselrs, hyundais, and mitsu's. Its the same engine thats in the new Genesis coupe. The only difference is the Evo motor has stronger piston sleeves.

 

[hhuricane]

Timing gears = very accurate timing, expensive, heavier and very noisy.
Timing chain = durable, somewhat heavier than belt, needs oiling, susceptible to chain whip on high rpm applications (automotive), accurate timing difficult on higher mileage worn chains, noisier than belts but not as bad as gears.
Timing belts = Very quiet, light weight, not as durable, higher maintenance, cheaper to produce.

 

[clone]

BUT, this isn't a fair comparison due to the fact that the bike's inner chains are tons smaller due to the smaller motors

it's absolutely a fair comparison, you are absolutely 100% wrong on this matter.

belts can do the job well enough.... chains do it that much better, gears even better but diminishing returns apply.

the problem is not size it's cost and btw timing chains in motorcyle engines don't have master links, they get pre stretched and then put together.... a master link would unbalance the chain at speed.

I'm not happy or unhappy with my timing belt..... it does bother me that so many Eagle Talons have died because of broken belts but such is the nature of the beast...... if I could change to a chain and it was a good setup for a reasonable price I'd do it in a heartbeat but that isn't the case so I'm stuck with a belt that I have to keep an eye on.

it's a minor gripe but an honest one.

chains are superior to belts without a doubt and will remain so until they start making belts out of the material they are using for Chryslers CVT system in the Caliber and Compass.