Thanks Ranchero!
Do you happen to have any photos of the radiator for the intake? Would the bumper need to come off to install a pusher fan?
I would like to try the pusher fan see, what that does to my temperatures. My main concern is drag strip where temperatures really go up. If I can keep it under 110f I would be a happy camper

 

The pusher will allow your temps to recover a little quicker, but still won't drop them below ambient, especially if you haven't isolated the IC system from the engine coolant system. Keep in mind, it takes a lot of heat to get water temps to move, but the converse is that once they're on the move and become elevated, it takes a lot to bring them back down as well. By starting at a lower temp, you'll be able to introduce more heat for a longer period of time before the water temp becomes unacceptable.

One thing to consider about that pusher- every pebble, stone, rock and piece of sand that gets kicked up will go through that fan and will munch your heat exchanger core. Get some screen from Home Depot or wherever and zip tie it to the fan to keep the bigger chunks out.

 

My goal to keep them under 110 at the track, runs well under that temperature. Maybe set up a thermostat system, but then again I would not want the fan to be moving while the vehicle is traveling at speed, how would I go around that ?

 

Question: why would the fan's status be of concern based on vehicle speed instead of IC coolant temp and IAT2?

To answer your question about making the fan speed dependent, one thing that comes to mind off the top of my head is to tap into the signal from the VSS. You could find the voltage range it produces via a scan tool, then look at what voltage it makes at, say 20 mph (if you wanted it to only run below 20 mph), and then program an arduino board to turn the fan on if the voltage from the VSS drops below that value. Or to simplify it, just use a relay that switches the fan off whenever it sees voltage from the VSS.

Personally, I think that a fan should be commanded by the temperature of the fluid it's cooling, not vehicle speed. In that case, it'd be as simple as an adjustable thermo switch to get the fan to shut off once the IC coolant drops to an acceptable level. However, IC coolant and IAT2 don't have a linear relationship, so you may want to pull signal from IAT2 so that if it's above a certain temp, AND the IC coolant is above a certain temp, the fan is on, and won't shut off until both IC coolant and IAT2 are both within your desired envelope.

 

You would plumb a thermostat in to run the pusher. Per the other question, I don't have any pics beyond what's on my build thread and the nose needs to come off for just about everything you do up there. Hood vertical and the vanity cover out of the way as well.

Per the fans you'd want an open design so they don't limit the flow through all the cores when the main fan is drawing.

Per Mandrakes comments about the combined system heating the IC coolant I think the only difference between the two is the expansion tank on the XKR has two burp hose ports. The back one gets really warm and the front one for the IC ckt just kind of sits there at ambient which leads me to believe that it's not flowing coolant from the hot side through the IC loop or certainly not much.

 

I'm confused about what you said in regards to the burp hose ports on the expansion tank. Mine only has one burp hose for the engine coolant and both the parts fische and the factory service manual reflect this. Then again, mine is a '10, so I'm guessing that if you have two, the 4.2's were different?

 

Yep, my '07 has two @ 1/2" hoses going to the top of the expansion tank. My tank is also divided in half with a small 'window' under the fill opening so you can see the level. The fender side is larger and fed by the inner cooler circuit. The engine side has the larger hose on the bottom and another 1/2" one on the top. The top hose warms up instantly on start up so I'm sure it's part of the T-stat bypass passage.

I mistakenly ordered the wrong expansion tank and got an XK one that I still think was cross referenced to an XKR somewhere and if yours only has one burp hose then that makes sense. It also makes me wonder of the 5.0l cars aren't sharing more of the cooling duties across both circuits and the 4.2l cars are more segregated?

 

Interesting. I looked on jaguarparts.com and on ebay at pictures of your radiator and heat exchanger, and neither show evidence of a crossover pipe between the two like we have on the 5.0L version. If you have two burp hoses, this would lead me to believe they are indeed divorced systems.

I strongly suspect that the 5.0L cars are sharing the cooling duties as you say based on the relationship my IATs and coolant temps vs. ambient temps over the past month. Admittedly, I only have half the story because I'm not able to see what the intercooler water temps are.

Something I just thought of... I remember reading a long time ago about these short ram intakes you see the kids putting on their Hondas and their effect on IAT. The figure stated in the article was that the air exiting the radiator is roughly 45- 55 degrees above ambient when everything is up to temp. Tying that in to what I've been seeing with my intake temps- My IAT2's are consistently between 40 and 60 degrees above ambient once everything is up to temp. Hm... Time to get a couple tee'd bungs and put them in both the inlet and outlet of the IC heat exchanger to see where my pre and post core water temps are. This doesn't really help you 4.2L guys, though.

 

get your self a laser temp gun , at about $15 on ebay there a great tool box addition . and very accurate . and you can the check the temps on infinite things . so also a pass time ;-)

 

I have one but unfortunately, external surface temps aren't the same as the coolant inside. It'll at least getcha in the ballpark, though.

 

Holy crap man were did you hear that from .
You have a rubber inlet and out let pipe ! The pipe keeps exact temp with the liquid inside it with a slight delay wilst increasing and decreasing temp but still exact !
Because nether the pipe Nore the charge cooler is insulated ,
It's no ball park figure I can promise you that !

 

Where did I hear it from? I dunno... some physics professors in college and a friend who's a Carnegie Melon grad that works with DARPA and then another friend who's a literal ex- rocket scientist, plus some engineers at Lockheed.

But yeah, you're probably smarter than those guys, so keep on truckin', bud.

 

I think it's a pretty moot point since we are looking at delta improvements vs. absolutes. Screw type thermocouple into the cooler shell or tied to the plumbing fittings would be relevant enough. The trick is getting repeatable data with an ambient reference. Garbage in, garbage out.

That's why I like a gauge arrangement vs. data logging. Gives me all the info I want at a glance while I'm doing something to reference it to.

 

Any car with a water to air charge cooler will heat soak around town, in stop and go traffic and when parked for 20 minutes. Get used to it. No air moving through the cooler. There is no way around it and fans do not help. The water in the charge cooler system absorbs heat and under the hood is hot period. These cars or any other super charged cars with water to air charge coolers do not lend them selves to drag racing - there is no cool down time, just heat soak time. All you can do is add an ice tank for drag racing but there is now where to fit one unless you want a trunk tank. You can split the charge cooler radiator, add fans, add Killer Chiller and it will still heat soak just as bad when parked or in traffic or cooling off from a run.
Normal IAT's for these cars on a 90 degree day is right around 110f - 115f on an open road or a road course ( which the car was designed for ) If yours are higher you have other issues. Splitting the system does nothing to reduce IAT temperatures once the car has warmed up and is driven in traffic, it will still heat soak, recovery is not quicker either. There is so little heat transfer between the two radiators and no flow between the two, just a connection to allow for expansion in the charge cooler circuit.
Jaguar engineers are no fools, if they could reduce the IATs by a any meaningful amount by splitting the system or adding fans etc can bet they would have done it.
Bottom line, the car needs airflow through the radiators and the only way to get that is by moving at a decent speed.

 

I don't think anyone is saying that the IC water temp won't rise under boost or while parked. However, I do believe the points you're missing are starting water temp and recovery time of said water after a run/pull.

 

I notice a big difference in performance during the commute home. Before I hit the interstate for the 15 mile commute the car is a rocket, after a dog. Somewhere along the line I'm losing efficiency and suspect it's in the IC coolant loop.

 

I should add that what I discovered slightly helps lowering the overall temperatures was removing the engine cover. From my observations runs 5-8 degrees cooler over all. After driving over a year with the cover off recently I put it back on to see if there would be a difference, and to my eyes there was , so cover is again off.

 

I noticed that as well, and adding water wetter dropped it another 5-8°F.

 

The IAT figure over OBD has to be post 'charger/cooler. I changed my broken S/C coolant pump out at the weekend. Prior to this, logging over OBD with Torque Pro showed IAT climbing steadily until around 85 celsius, then the car hitting Restricted Performance mode. After changing the pump the IAT figure climbs to around 38-42 celsius depending on load, so the reading shown over OBD simply has to be the one taken later in the system, not the MAF readings.

88 celsius IATs are no fun at all too, in case anyone was wondering

 

An often overlooked heat source is the heated throttle body. There is a coolant running through ports on the throttle body. This is an ancient engineering concept to avoid carburetor icing or throttle body icing, which is more of a problem in aviation.
Many modern motors have this little addition. The GM community has been deleting this for many years without any adverse effect. I did it on my XK several years ago.
I never measured before/after intake air, but it is sure to have some minor effect.