Chain VS belt drive

[corvette66]

I keep looking at these sbc timing belt conversions and asking myself how could these really be more reliable? I have seen and heard of many people using these, and actually loving them. I have seen in the adds that they claim "more reliable than a chain" I'm not yet sold on the idea. I know it would require less power to run it, and it's probably more acurate, also its easier to change and make adjustments, but it's open to the elements. In circle track racing i have seen rubber tire chunks build up on cam sprokets and cause a belt to jump teeth and even fall off. Any thoughts? Anyone have one, or used one?

 

[LanceB]

My Dad had a Porsche 928 at one time which I believed had a similar timing belt to what you described. If it went, the car was pretty much totaled

 

[MikeMc71]

If you consider water cooled Volkswagens all have them, that itself would say something about reliability. They suggest them being changed every 60K miles.

There is quite a difference in HP between the two, I am not sure how the belt would handle that. I have spun the timing belts on VWs in the past, the gas were ok because of clearance between the pistons and valves, but it will destroy a diesel VW.

 

[Vettehead Mikey]

I know it would require less power to run it,

Says who?

 

[JohnZ]

I keep looking at these sbc timing belt conversions and asking myself how could these really be more reliable?

When I see them, I keep asking myself why anyone would even consider one, much less buy one. The chain is dead-reliable, the design is bulletproof and has been proven over billions of miles; the belt conversion is a solution looking for a problem that doesn't exist. Requires less power to run it? Hardly - just more marketing hype - you'd need NASA-level instrumentation to measure any infinitesimal difference. :eyerole

 

[Vetsvette2002]

I know it would require less power to run it

If the only positive to the use of the v-belt is the cost to the large volume engine manufacturer. There is no power loss that anyone could measure, accurately and with repeatability. But then I only have 35 years of engine engineering for manufacture and racing so WTF could I know

 

[Altered]

I keep looking at these sbc timing belt conversions and asking myself how could these really be more reliable? I have seen and heard of many people using these, and actually loving them. I have seen in the adds that they claim "more reliable than a chain" I'm not yet sold on the idea.

First thing is there are several different types of after market belt drives. Some have a idler/tensioner, and then you have the wet and dry belt versions. That being said different types are designed for different uses. Those open belt drives that you see are called "dry" and are strictly designed for Race use such as drag racing or NASCAR. Places that the tracks are a hard surface and swept or blown clean regularly. They were never intended to be used in daily street use for obvious reasons such as rocks mud dirt etc etc getting into the system causing failure. Used in the proper environment, they have proven more reliable when using large cams that require high valve spring pressures. The belts do not stretch like the chains do causing timing fluctuations.

I know it would require less power to run it, and it's probably more accurate, also its easier to change and make adjustments,

You sort of have it right. They don't take less power to run, but they do free up more power. The way this works is by separating the harmonics coming from the crank from getting to the cam. This helps control the lifter to cam contact and every other piece of your valve train from harmonics generated from the firing of each cylinder. This allows the engine to produce slightly more power basically through better efficiency. This is much more noticeable on race engines with small base circle cams using large amounts of spring pressure to keep the lifters on the very aggressive ramps at high RPMs.

In circle track racing i have seen rubber tire chunks build up on cam sprockets and cause a belt to jump teeth and even fall off. Any thoughts? Anyone have one, or used one?

Many use these in circle track racing as they consider the risk minimal and are willing to take the risk so they have quick access to make cam adjustments as necessary for varying track conditions. Along with the other benefits.

FYI
Gear drives are nearly indestructible but these sap the most from your engine as they are a direct metal to metal link sending every harmonic strait through the cam.
Chains are the most common as they provide a slight break in harmonics from the cam and in most cases can handle mild street engines.
Belt drives offer the most benefit for people running large cams with high spring pressures trying to get every ounce of power from the given combination. Don't forget you get the bling factor as many think its cool to see the belt running.

Hope this helps explain it a little better. :cool

 

[corvette66]

This is all good info, actually forgot i posted this. Was out of town over the holiday. just got back. Thanx for the replys. I have a nascar engine in my 69 and that was the real reason i was considering it, (the "bling factor") I won't be driving it much when its all done, have to run 100 octane + But i think i will throw the idea out the window anyway. Too many risks. why replace something that works perfectly fine, such as the chain