What exactly dose a interfirence engine do. Whats the difference between that and a normal motor?

 

it means that if the valves were to be open and the pistons at top dead center, they would be occupying the same space. they have minimal clearance and timing is even more important.
this means if the timing belt were to snap while the valves are fully open, the pistons will smack them. a non-interference engine would not have to worry about that.

 

engines like ours are interference. V8's and V6's and a non interference. As long as they are not a OHC

 

An interference engine is called that because when the valves open, they open far enough down that they are in the space where the piston does when it's in the Top Dead Center position (it's highest point of travel). The idea is that the valves opening that much more allows for more air/fuel mix to flow into the engine thus increasing it's efficiency.

On the other hand, a non-interference engine is one where the lowest point of the valve travel is still higher than the Top Dead Center position of the piston.

Why this is important is if your engine is an interference type and your timing is off by a large amount or the timing belt lets go, the valves will crash right into the pistons thus destroying your whole motor but if the engine is a non-interference type, then there is not as serious of a risk if and when the timing belt snaps.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Racermech &raquo;</TD></TR><TR><TD CLASS="quote">engines like ours are interference. V8's and V6's and a non interference. As long as they are not a OHC</TD></TR></TABLE>

That is not always true. There are several overhead cam-headed engines which are non-interference as well as many 6 and 8-cylinders that are interference engines. Cylinder count and arrangement is irrelevant to deciding whether or not an engine will be interference or not.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Racermech &raquo;</TD></TR><TR><TD CLASS="quote">engines like ours are interference. V8's and V6's and a non interference. As long as they are not a OHC</TD></TR></TABLE>
i haven't seen any evidence one way or the other that b18bs are interference. i've broken a timing belt on mine with no hits, and have heard of other people breaking belts with no damage. but i've never heard of a b18a or b messed up from a broket t belt. so if you have any conclusive info, i'd be happy to see it.

 

There has been many posts with pics about timing belts going at high speeds. Believe me, it isn't pretty. The pistons had holes punched right thru them. Do a search.