On my latest 4K mile road trip through the Southwest I was having apparent
vapor lock problems when the engine and fuel lines were heat-soaked; i.e. after
driving in hot weather, shutting down then restarting after 30min or so. At
startup, the engine would stumble a bit until I got moving and got some air
circulating. I'm thinking maybe a ceramic coating of the manifold and downpipes
might alleviate this problem. Also wondering--this is mostly a pipe dream--what
coating the entire exhaust system would do. I would think at least it would
lessen the heat under the driver.
I haven't had this problem until the last few years, which coincides with the
greater prevalence of alcohol-laced gasoline. I can't prove a correlation, but
if the vapor pressure of gasahol is lower than 'real' gas then it could be the
cause. We tried to find a station that pumped pure gas for comparison, but east
of CA--and in most of CA--the pumps all read 'Contains Ethanol.'
bs
--------------------------------
Bob Spidell - San Jose, CA
I just wrapped my downpipes with a high tech wrap in hopes of cutting down on
rough idle (vapor lock or gas getting to hot???) at high outside temps and in
stop & go traffic.
Did you notice any difference in this area?
I'm driving the BJ8 to AZ next month and will update.
Randy
On Aug 26, 2010, at 12:05 PM, Bob Spidell <bspidell@comcast.net> wrote:
> As long as we're on the (neverending) topic of heat management--thermostats,
>etc.--has anyone done a before/after analysis of manifold/downpipe ceramic
>coatings (JetHoat, etc.) and the effect on engine temps? I know we've
>discussed it before--and there seems to be some anecdotal, positive
>results--but does anybody have any definitive info to add?
>
> I wrapped my downpipes, and the net result was seemingly hotter gases at the
>exhaust exits--I didn't actually measure the temps, but the exhaust went from
>hot to pistol hot--circumstantial evidence that more heat is being moved away
>from the engine compartment. I can't say I saw a measurable decrease in
>coolant temp, but unless you do before/after testing under identical ambient
>conditions it's going to be subjective at best.
>
>
> bs
>
> --------------------------------
> Bob Spidell - San Jose, CA
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