silent lucidity

iTrader: (1)

Some talk on crossovers,,, leads me to the question. Why do some motor builders when pro or supercharging an MPI motor like to leave the thermostat out all together?
They say they recalibrate the ECU to not run in a rich condition when seeing a cool engine...
I would guess the motor would run in the 120's instead of 160.. They say a cooler motor is a happy motor but at what temp do you cause issues with ring seal etc..
Just a topic for discussion...for you motor heads.

ezstriper

the ones who try to run no therm aka procharger is merly a bandaid to fool the ecm into richening the mixture..a B/S way of trying to get to run rich enough without the costly reprogram of the ecm. if you run a crossover(which I did) with no bypass and therm will run way to cold to get rid of moisture in the oil...you need about 150 to get it cleaned out..

Haley'sComet

Would you be saying that if you ran without thermostats, your oil temp wouldn't get too hot??

I'm asking because on my boat, as I got it from the seller, (with twin 454 Mag's) is running crossovers and it wasn't running any thermostats or oil coolers...

silent lucidity

iTrader: (1)

From what I understood the oil temp does come up to a safe level but the motor just runs cool all the time getting rid of all the extra heat generated by supercharging..
The ECM is actually switched to an MEFI 4b which will allow you to control fuel based on boost pressure and programed not to run rich because of temp..
Is 150 the point at which moisture or fuel is removed from oil..? Leaves one to ponder...

seafordguy

I'm not smart on these topics but I try to make sure I get my oil temp over 212 when I run it at least at some point during the run because that is the boiling point of water.

That might sound stupid - but that is my goal normally.....

hotjava66

Any more info? I am running crossovers and considering changing to ones with a thermostat setup. I never build any water temp, but get plenty of oil temp if I run hard. I wonder if adding t-stats will push up oil temp into unsafe range?

silent lucidity

iTrader: (1)

Looking back,,, these crossover topics have been around several times.. But looks like all over the board on pros and cons.. Even to the point that some go back to the circulating pumps.
I would like to add then to my twin 454mag mpi's but have concern as to what the right set up would be..
With or with-out thermostats,,,???
My biggest concern without is the on rush of cool water into a hot motor and causing cracking of heads, etc.

Philm

That isnt really a valid arguement though, because its not like you will be running without water or with very hot water in the heads, then all of a sudden you will get cold seawater coming through. The seawater will always be coming into the engine and wont have the temperature fluctuations that a thermostat would cause inside an engine.

I run an open crossover with an oil thermostat. Water temps NEVER get over 120ºF and I never have problems with condensation in oil.

ezstriper

I ran mine both ways..when I got the boat had a crossover, no bypass no therm, ran to cold, oil temp stayed to low and had condesation bad in the valve covers. changed to a crossover with a bypass and a 140 therm with a couple of 1/8 holes drilled in it..now runs constant 150, oil temps good, no condinsation and picked up fuel economy in the cruising range....

PatriYacht

The main advantage to running a crossover without a thermostat on a supercharged engine is that it keeps the heads cooler and lessens the chance of detonation. Also, the cooler temps increase mixture density and that results in more power. And, of course, there's so much stuff on the front of a supercharged engine, it's just easier to plumb.