Low temp thermostat-Mercury Marine

[EFISYSTEMS at aol.com]

Hi,
      Since we're going to continue with this temp thread I might as well 
throw in my two pesos worth.....The last Merc projects I did were the magnum 
454,502 and 500hp(500hp 502) all of these had 180 degree thermostats in 
them...(btw their calibrations suck, many times I found 16.5:1 to 18:1 holes 
at part throttle) We were installing Supercharggers on them and found we had 
to retard the timing 6 degrees to keep it out of knock on 92 
octane......until we removed the thermostat then could go back to stock 
timing,,,,engines ran approx 120 degrees,,,,intercooler water was at lake 
temperature on all tests.  Now by no means do I think running an engine at 
that temperature is optimium,,,,but, it is what worked in this environment 
because of lack of octane.......I for one have had the slogan "Heat is 
energy, energy is horsepower, if controlled" for many years......but true, 
how many controlled environments do we have???? The real world is not a 
laboratory.....I still have pesos if someone wants some.......<G>
-Carl Summers

In a message dated 10/27/99 10:28:40 PM Pacific Daylight Time, 
bob at tecmark.com writes:

<< Subj:     Re: Low temp thermostat
 Date:  10/27/99 10:28:40 PM Pacific Daylight Time
 From:  bob at tecmark.com (Bob Valentine)
 Sender:    owner-gmecm at esl.eng.ohio-state.edu
 Reply-to:  gmecm at efi332.eng.ohio-state.edu
 To:    gmecm at efi332.eng.ohio-state.edu
 
 >Andrew Choset wrote:
 >> AS&M built them?  I had always heard that it was Mercury Marine that built
 >> the LT5....
 >> 
 >> Andrew Choset
 >> 88 IROC L98 T56
 >AS&M= firehawk
 >MM= LT5
 
 Amazing how Merc took GM sb/bbc's, fits them to boats where they don't live
 very long, but they can build a different GM motor which runs great in a
 land vehicle and GM contracts them to do it. 
 
 More fuel for the low temp 'stat issue:  most Mercrusier thermostats are
 140 degree - and my temp guage usually shows something close to that, mabye
 150 degrees since there's a unlimited supply of 55 degree cooling water.   
 
 If according to Jenkin's book the optimum temp is around 200 degrees, then
 why didn't MM go higher?
 
 I run a GMC 292 inline 6 in my boat, so it's not exactly a hotrod.   The
 little simple as dirt 2bbl rochester never fails, so I've yet to consider 
EFI.
  >>