It seems that unreliability is often caused by modifying the engine. This makes sense logically, but I think there's more to it than that...

 

If you modify an engine to make it capable of handling more power, you make it stronger...unless you drive it to it's limit a lot of the time, shouldn't this make it more reliable ?

I know many parts of an engine are stressed by higher performance, and they cannot be modified/strengthened...so are these the sources of unreliability ?

 

 

Unreliability is a) relative and b) caused by unfitness for purpose.

 

Examples

 

1) A Ferrari F1 engine lasts for (my guess) less than 3 hours and less than 300 miles under race conditions. This is bloody unreliable if I want to drive it to work today. But is quite reliable enough (dammit) for F1

 

2) If I drove a Ferrari F1 to work, it wouldn't last 30 minutes. The clutch would break, the engine would overheat, the sleeping policement would strand it and the first time I kerbed the damn thing while trying to change the CD, the suspension would break.

 

You don't make an engine capable of handling more power, you make it capable of delivering more power.

 

You have two basic choices: increase power output (and beef the internals to cope) and decrease friction.

 

For example, taking an engine apart and blueprinting it will both increase power and reliability. Usually.

 

Winding the boost up (without doing anything else) will undoubtably get you more power but just make your engine more fragile.

 

An engine is a collection of compromises. One of your limiting factors may have a margin of 100% so you could double the stress on this component without trouble. But this may affect another component which only has a safety margin of 20%. Result? Bang.

 

How do you find out which is which?

 

Trial and Error (Break a lot of engines)

 

or

 

Engineering (Have a lot of experience and money or access to these).

 

By guess and by God just doesn't cut it any more.

 

(oh look - my favourite post number)

 

[This message has been edited by Gio (edited 06-07-2002).]