this may sound naive but why do interference engine exist?

lorolia · 08-31-2008, 01:55 PM

Just want to know...

and something else...

why a belt is used? wouldn´t be better to use a chain?

ron1004 · 08-31-2008, 02:01 PM

It's the quest for incredibly high performance from a small engine - open the valves real wide to get as much air in and gas out as quickly as possible.

lorolia · 08-31-2008, 02:05 PM

so that means using a chain doesn´t allow high performance?

and also means a non-interference engine is not made for hi-performance?

ron1004 · 08-31-2008, 05:19 PM

Quote:

Originally Posted by lorolia

so that means using a chain doesn´t allow high performance?

I responded before you added the Q about the chain.
No that's not what was said nor implied. I'm sure you could find one when searching for your next car - do you know of any on the market now.
Remember that cost also plays a role - how many cheap rear wheel drive cars do you know of - I know Merc and BMW are rear wheel drive, but out of the price range for most of those folks looking at cheap compacts

and also means a non-interference engine is not made for hi-performance?

I'm sure you could find them

What is actually your question?

Lets not turn this into a gripe thread about the Rio being an interference engine. Its not the only maker out there with belt driven camshafts on an interference engine.

lorolia · 08-31-2008, 07:29 PM

Quote:

Originally Posted by ron1004

Lets not turn this into a gripe thread about the Rio being an interference engine. Its not the only maker out there with belt driven camshafts on an interference engine.

I know that and to be honest with you and all...that´s not my intention at all

part of my question arises because I was wondering (maybe this will sound stupid) if chains do ever need to be changed under normal conditions?

so my question is: even if I had a chain instead of a belt, would I always need to change it after lets say 10 years of use?

here in latin america we can´t change our cars every 4 or 5 years. We think long term use so one expects to have a car around 15 years and was wondering in the hypothetical way if after 10 years a chain has to be changed too.

ron1004 · 09-01-2008, 02:22 AM

OK.
Chains are known to get worn and very noisy and would likely need replacement before it would be considered necessary to overhaul the engine, so in this case you could have changed a belt and continued without opening the engine.

I've changed a chain by attaching the new one to one end and pulling it through which only needs the top cover off, but this is not always ideal because the hydraulic tensioners wear and need replacement.

Wrench4Life · 09-01-2008, 06:38 AM

Chains are not trouble free. Mercedes has had several issues with chain guides, so have Nissan and Toyota. And certain designs had chain stretch issues. Modern chain driven cams are very reliable and have improved dramatically. Belts can be used for various engine designs and packaging requirements. Also all belts are not designed equally, some belt driven cams have a well designed belt and good tensioner and pully angles which prolong belt life.

Why are engines interference, well there are several reasons, flow of the cylinder head, combustion swirl, interchange, lower cost, higher compression. Most engines can be designed to be non interference ie the SPI 2.0 ford CVH engine it used 44 MM intake valves and 37 MM exhaust valves, the pistons were deep dished and notched. It is a non interference engine. Honda uses interference designes, but with a stronger belt, better pully design and better made parts so timing belt breakage is very rare indeed.

2004riotuner · 09-01-2008, 07:22 PM

A belt was used on the Rio because of the fact it is basically a Mazda B6-ZE 1.6 engine. To the tune of 10 more HP then the Mazda engine and better fuel efficiency. Tooling cost alone to change the system to a chain would be near the same as redesigning the engine. Secondly the A5/A6D both have a higher 10.0:1 compression ratio and also a better rod ratio Giving the engine it's ideal 104hp/104tq arrangement. The B6-ZE is around 95hp/88tq. It's all in design. Though the engine may have been made cheaply Kia felt that people would possibly make an attempt at reading the owners manual and realize that maintenance would need to be done, be it changing the oil, fuel filter, spark plugs etc etc. Though such isn't the case most times. People leave it and neglect it and that is how it happens. The vehicle may be cheap though just because the vehicle is cheap to purchase may not (and usually never) mneans it is cheap to repair, especially off shore vehicles.

DIYrio · 09-02-2008, 06:42 PM

[quote=Wrench4Life;220983]Chains are not trouble free. [quote]

It's true. Chains aren't a sure cure. My brother bought a 1995 Nissan 200SX with 12K miles on it. He is the "gas-and-go" type of car owner. Around 120K miles he complained about poor performance and noise form the engine compartment. My dad and I asked if he wanted us to take a weekend and do a once-over on the car. He put it off and the chain failed a few thousand miles later. It was a total loss.

The KIA is not suffering from poor design. Rather, due to KIA's value priced product, many who purchased these inexpensive cars were not financially able to maintain the vehicles. Because of it's sound but efficient design, it is a maintenance intensive vehicle. A less efficient design could be more rugged and less maintenance intensive, but would not get 38 mpg nor would it sticker around $11-14k.

On this forum I have read some pretty harsh words toward those who have just lost their transportation (due to poor maintenance or adequate maintenance and poor luck). Let's be a little kinder to those who are mechanically (or financially) challenged.