[Vwdiesel] Head gasket thickness
Terry Briggs
vbriggs at stny.rr.com
Thu Nov 29 15:48:10 PST 2007
ok, that was it, I found the article and it's as you say, better
starting. So ... if we could lower the cr to 18:1, how would we aid
starting ....
On Nov 29, 2007, at 2:19 AM, LBaird119 at aol.com wrote:
> In a message dated 11/28/2007 4:12:47 PM Pacific Standard Time,
> vbriggs at stny.rr.com writes:
>
>> Actually I think it's more thermally efficient at higher compression
>> ratio's, burning fuel more completely. They only lower it due to
>> mechanical restraints. Makes it harder to contain the magic smoke the
>> higher you get the cr.
>>
> Well, according to a diesel, class instructional book I have,
> the main reason they go with higher compression is for better
> starting. I never did read the whole SAE paper on the 1.5 but
> I've had a couple people tell me that it says VW found 18:1 to
> 19:1 to be the most efficient but chose 23:1 for dependable
> starting. The same book covers an experimental, variable
> compression diesel, where the pistons are basically like big,
> hydraulic lifters. As cylinder pressure increased, the pistons
> would compress more, giving lower compression. The efficiency
> and power output was about double of the fixed compression
> version! :-)
> Once you get to a certain point, pumping losses exceed the
> higher compression gains from an engine. I'd suspect that
> number is somewhere between 16:1 and 19:1. I know with
> Dad's pu, as the rings and all seated in, it LOST power. Turned
> out it'd had the wrong head gasket, I replaced with the same
> back when that's what you did rather than measure. We had
> 700 to 750 psi compression!
> You could actually feel the sluggishness as compression
> increased and robbed power.
>
>
>
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