Okay, I know this will trigger the age-old debate about potential benefits/cautions about using a lower thermostat but I will ask anyway.

On my previous car (Corvette), one of the first things the gearheads did was to install a lower temp thermostat (160-degrees versus the original 180-degrees). In fact, there were a bunch of vendors that packaged basic "performance" kits that included lower thermostat, throttle body airfoil, K&N air filter, etc. I can say that I NEVER had any problem running the lower temp stat for the 14 years that I owned the car but I live in SoCal where the outside temp is typically averages around 70 or more year round. In fact, the result of installing the lower thermostat and programming the radiator fans to come on sooner resulted in engine temps that were about 20 degrees cooler than stock (the LT-1 engines consistently register temps of about 200+ on the gauges in stock form and this was reduced to about 180).

Of course I realize that to really get any potential improvement from running a lower stat you should really reprogram the timing/fuel maps to compensate and while this was easy with the Corvette (Hypertech programmer and other similar devices), this cannot easily be done with the Jaguar.

Nevertheless, has anyone tried using the thermostat that is offered by one of the vendors out there that is supposed to be 13 degrees cooler than the stock one?

Thanks,

Doug

 

Doug, I know the stype-r guys have been putting in the low=temp t-stat. You may want to ask Mafioso or any other of the R guys doing performance mods.

 

I have one in my hot little hand and will be installing it soon, along with a 3 lb. pulley upgrade. It is a 170 degree thermostat from Eurotoys. I suspect that is about as low as you can go and guarantee that you will still get into closed loop mode.

I will report back after the install.

 

WhiteXKR--I am eager to hear how any mods you try work out. I believe that to get any real benefit from the lower thermostat you would also need to program the fans to come on earlier (at least that was the situation with my last car). I am not sure if this is the case with the Jaguar engine and, even if it was, there does not seem to be any do-it-yourself hand-held programmers or laptop software readily available that would allow you to make any changes to the engine management computer.

Doug

 

@Doug
Best would indeed be to re-program the fans, as when you are driving with low airflow (ie city/traffic) the temps will go up until 97 degrees C before the fans kick in (regardless of which T-stat u use). But for all other occasions where you do have good airflow (highway) the temps will be lower.

One thing though, I experimented once with a lower temp t-stat on an 4.2 Stype, and the ECU didn't like it, as it compered the time the coolant got warm to the actual times. On the XKRs the T-stat is very easy to swap, but on the stype it is more work, so I abandoned that for these cars. The 4.0 cars do not have this check.

 

I have been seriously considering adding a manual fan override (or retrofitting a thermostatically controlled fan override).

I have had lots of distractions lately (life intrudes on the fun sometimes), but will get this done and report on my results. I plan to dyno the car eventually (I know, I know, I should have done a baseline first ). I am also waiting and hoping for the new intercooler design from Nameless Performance.

I know this will never come even close to Avos' twin screw mod, but I am having fun within my budget.