MFI warm up thermostat-how important??

Steve in SLO · 04-08-2002, 08:59 AM

I am installing a 2.7 MFI engine in my car. The MFI was formerly used in a race car, and has the warm up thermostat blocked off. I have all the parts to put it back on, but to use it would need to have a tube welded onto my SSI's before installation. Just how important is it to have this on a street car? I live in CA, where the temp rarely goes below freezing. BTW, this is a 10.3:1 dual-plugged s-cam motor. Thanks to any MFI gurus out there.

Early_S_Man · 04-08-2002, 09:30 AM

Steve,

Unless you don't consider good behavior and drivability during warmup important, put the thermostat back on!

Paul Thomas · 04-08-2002, 09:48 PM

I have headers so i took mine off and have had no complaints. I also blocked off that rediculous stop solenoid.

Paul

jkeyzer · jkeyzer's Garage

Paul -

What did you replace the thermostat with? A bolt to push the lever all the way back? It is my understanding that the default (not pushed back) is full rich.

Wayne 962 · Wayne 962's Garage

Both the solenoid, and the warmup t-stat are vital to properly controlling the mixture, and backfires...

-Wayne

Bobboloo · Bobboloo's Garage

On my heat exchangers the pipe that feeds the hose to the thermostat isn't even welded. It's just a snug fit. Then again maybe mine is a mod of earlier exchangers.

At any rate it should be an easy job. So why not do it.

As matter of fact I'd be willing to swap my 2.4T motor with yours as a kind gesture so you won't have to go to all the trouble.

Bobby

Steve in SLO · 04-09-2002, 06:42 AM

Quote:

Originally posted by Bobboloo

As matter of fact I'd be willing to swap my 2.4T motor with yours as a kind gesture so you won't have to go to all the trouble.

Bobby

The thing I like most about this board is that there's always someone willing to help me out.

Thanks all for the input...I think I will put the stuff back on.

campbellcj · 04-09-2002, 11:17 PM

I'm kinda curious about this too...for a 'simplified' setup, i.e. a race car that is configured to only need to run well (or even properly) when warmed up, what would you need to do?

Specifically, what if you have headers instead of the stock left-side MFI heat exchanger with the preheat hose, you disconnect the enrichment and fuel squirter circuits and also the thermostat?

What configuration did the factory MFI racers use? Surely they didn't run full heat exchangers, solenoids, thermostats, squirters, air filter plenums and so forth...or did they?

Paul Thomas · 07:02 AM

I did the exact same thing on my pump that Hanz at H&R Fuel injection does to pumps. I made a small plate to go over the hole and put a threaded rod in the middle to adjust in and out. As far as the stop solenoid, that thing is for emissions so that the ammount of fuel is cut back when you are deccelerating. The result on my car was that the motor would cut off because the fuel was cut back too much. Disconecting it was also recomended by Hanz.

The factory RSR's had a small switch on top where the thermostat was on the pump that one guy would hold full rich while someone else started the car and warmed it up.

Paul

304065 · 04-10-2002, 09:30 AM

Chris:

Check the archives for a post by The Maestro, Roland Kunz. He goes into detail about how Porsche used a 12v bulb inside the thermostat inlet that would heat up as the engine ran.

My E race car has EVERYTHING stock: not only is it required by the rules, but you don't want to stall in the paddock.