[V8] MPG - contiuing saga

[urq]

... was the engine cranking over significantly slower when it was cold?  Had 
you removed all the spark plugs?  Did you have the throttle @ WFO when 
cranking?

The alloy engine should have no impact on the dynamics of the engine 
operation.  If anything coefficients of expansion should be better matched. 
Perhaps the cylinder(s) that has the big change between cold and warm 
compression has rings that are worn to the point they don't seat when the 
engine's cold ... or perhaps there's something in the valve train that is 
not allowing the valves to fully seat when cold ... all guesses.

I've been tempted to buy myself a bore-scope to be able to peer into the 
inner workings of the engine to try to understand things better ...

Steve B
San Jose, CA (USA)
----- Original Message ----- 

> With my recent troubles regarding a compression test on my '91 V8Q, this 
> has
> had me wondering. Is some of this caused by the aluminum block? I've never
> done a compression test on another engine with aluminum cylinders, so I
> don't have anthing else to go from. But, it really makes me wonder.......
>
> When cold I got 15 - 120 PSI. After squirting oil in the cylinders, I got
> 30 - 130 PSI. When warm, I got 165 - 180 PSI. This is on a 325K engine, 
> BTW.
> Wonder about lower milage examples.