Momentum V122

[Donnyboy]

Thanks to everyone that posted about today's momentum. I know very little about how the inside of a car works, so it's nice to get some insight from people that do. Most of today's blog might as well be in a foreign language. How do you guys interpret it overall? Positive or negative? Does the engine sound like it will be reliable? They make it sound like the compression ratio(whatever that is) could be a problem with 87 octane gasoline. I had a car that used to "knock" if I used the really cheap gas in town, so does this mean their engine will be prone to knocking? Does their engine sound like off the shelf technology or something new and risky? I know it's a lot of questions.

 

[Made in USA]

It will be more prone to knocking only if the octane is less than 87. The computer should keep the engine running smooth otherwise. So far the engine looks like it's been well thought out. Until we actually see about a test drive though, we don't know if their engineering covered all the bases. With the lightweight body the engine timing belt shouldn't be stressed much and should last a very long time. Some of the stresses are also related to the transmission. As they are getting the transmission from an experienced maker, this shouldn't be an issue.

 

[electroken]

Unless I missed something important in my training, pretty much the only thing that stresses a timing belt (or chain) is the combination of valve spring pressures and the profile of the camshaft(s). Beat on it and the last thing to break will be the timing belt.

 

[Made in USA]

As the crankshaft drives the camshaft there is a slight torque delay between the two. It is very slight, but it is there. Whichever is used, the chain or the belt are tighter on one side than the other especially when the engine is accelerating hard. How fast the engine can accelerate is also influenced by the transmission and the tire traction. Because the Elio is "efficient", it is basically detuned to a slower response for best gas mileage. Another way to look at it, nothing is 100% efficient so there are stresses on both chains or belts. In the Elio case this should be minimal and never be an issue with either chain or belt.

 

[Ty]

Right you are. I've also changed several timing chains in my day. One was on a 1981 Mazda 626 four cylinder. That one was actually easy once I figured out the chain tensioner. Belts aren't all that difficult to change either. Usually, you have to support the motor from beneath and disconnect the front engine mount to get the new belt on. The hard part is getting the chain/belt cover off. After that, it is pretty straight forward. Having said that, timing belts are a LOT better than they used to be and should last more than 80,000 miles. It could last even longer with such a low power engine such as on the Elio. 80,000 miles is more than 5 years @ 15,000 per year. I expect my Elio to last longer than that but figure I can save up the $20-$30 that the belt will cost and the $10 or so for the timing belt cover gasket. Easy Peasy.
The cost of replacing the belt will be negligible because I'll install it myself. It pays to be handy. Hopefully, it won't be too much of a pain to do but if it is that just means it'll be more fun.

 

[Rob Croson]

I have no idea if the cars I've owned over the years have had timing belts or chains. All I know is that I've never had to replace either one.

 

[W. WIllie]

Timing belts run hot when covered. Ford is still using belts on a few vehicles, but they run "bathed" in the oil. Keeps them cooler and last longer.

 

[Donnyboy]

So it sounds like the small engine will be less complicated and probably more reliable. Simple is good! Cheaper to maintain and less stuff to break. The 4 cylinder engine in my Sentra is very cheap to maintain. Oil changes are cheap. I'm looking forward to 1 less cylinder and 1 less tire. Save $$$

 

[electroken]

I'm still not used to the idea of timing belts within the crankcase.

http://www.dayco.com/timing-belt-in-oil-bio-system

 

[Kuda]

In the following video, engineer Cody from IAV says a belt has less friction than a chain but they went with the chain for reliability.

EM changed their mind and went with a belt, which Cody says has less friction. Was this to achieve the 84 mpg, or cut costs, or something else?

It is at time 8:30

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