So, related to this thread: https://www.jaguarforums.com/forum/x...-paint-212308/

I've stripped my car to make it ready for a respray, and I was driving it to the guy who is going to do the paint job, and the car temp instead of running at the bottom of 'N' was running at the top or a tiny bit above. It was actually a very mild day today (61F/16C) so it was a bit surprising. Not sure if it's the spoiler, the bumpers, or both, but it apparently really changes the airflow.

 

That chin spoiler is a working part of the cooling system, and I know many have ripped them off, accidently, and noticed temps rise shortly afterwards.

Incoming air cannot exit the engine bay quick enough without it in place.

 

Mac
Further to Grant's (obviously!) correct reply, the function of all chin spoilers is to make a low-pressure area under the front of the car. This actually sucks air exiting the radiator downwards and out. I actually, inadvertently, did a test that proved this. My car has the AJ6 intake stuff on it, and at the time it was fitted, AJ6 provided a second inlet to the each airbox with a flexible duct. On my car these were fitted by the garage pointing downwards just underneath the bottom of the radiator, half an inch above the undertray, with the intention of collecting cold air. I was doing some intake air temp measurements a couple of years ago, and found that these secondary inlets were actually registering much higher than ambient temps!
I then moved them experimentally so they pointed forward, just under the undertray, and bingo, air temps dropped to ambient. So for years these extra inlets were intaking warmed radiator exiting air being pulled downwards by the low pressure under the engine! Now fixed with a permanent solution.

 

does sounds logical , but i have no problem with coolant temperatures, average digital temps. are 180/185 F when ambient is average 80 thru 90F , even reaches 95F and digital gage!
altho when stopped after hard run , 10minutes later heat soak goes up to 195F . never seen 200F in 26yrs! restart and temp goes down to 185F, couple minutes!

the under cooler is for trans oil, radiator deleted!

my inlet filters are open in engine compartment, when dyno it ,shop had large overhead fan blowing down, tried it hood open and hood closed ,3to 4HP difference !
i use an Electric fan and the small factory elec. fan.

hey works for me , but i cant count how many Jag V12s i've seen go down racing at Daytona 24 hrs, and many regular XJS seem to overheat, after a long time at speed, when they slow and come in for stops, temps go sky hi, and cars do start boiling out coolant, short excerpt from TWR chief Tech!

from TWR racing program!

 

The chin spoiler also helps reduce front end lift at high speed.

 

.

that could very well be true , but i'v had it to 130/135mph and it is quite stable.

the aero dynamics of the XJS , the drop center of the hood/bonnet does put some down force on the nose of the vehicle!
altho lately i dont drive that fast anymore,,
Hey good point ,HOW MANY HERE HAVE DRIVEN OVER 125 MPH WITH THERE XJS, or driven to the 150mph, on the speedo??
ron

 

of course Allen Scott of TWR racing doesnt know much anyway!!???, .

OK i'm just being facietious .
ron

 

Ron
There is no doubt at all that a properly mounted spoiler and undertray make a huge difference to the XJS's high speed stability. At anything over about 110 mph this is very noticeable, and anything above 125, including right up to 150 plus, both the directional stability in response to steering inputs and the generally "planted" feel of the car are far superior. I am not saying your car is not OK at speed; but I am saying, in coupe form at least, the correct aerodynamic parts make an enormous improvement.

 

Ron,

Very close, 225KPH, oh boy, things move very fast at that speed, and like you, I dont anymore.

The HE was rock solid, to my feel anyway, at that speed.

 

My XJS was the most sure-footed-at-high-speed car I've owned. I don't recall going higher than 120 mph, though.

Going 100 mph was routine, however. In that era of my life I did a lot of road trips and I used to make it a point to hit 100 at least once per outing.....just to....um....er....make sure there all the oils were well churned up. Proper care and all that

The XJR I drove for many years, while a great car in many respects, did not feel as secure at 100+ mph as the old XJS

Cheers
DD

 

That is because it was not! As an aside, when the rather unloved XJ40 saloon styling was updated to the far more attractive X300, it was accepted by Jaguar engineers and noted by some of the more knowledgeable road testers, that the restyle increased front end lift and reduced the XJ40's high speed stability somewhat.

 

I did 120 a couple of times when I was abroad.
Found out when I got home that the speedo was reading 17mph low.
This was in a V12 cabby with the roof off, and she was dozing in the passenger seat and if it wasn't for the scenery whizzing past it felt like we were doing about 40.

 

OK i give up, what is a cabby with the roof off??

 

Cabriolet!

 

i have no top , but if it rains, air flow goes over the top of windshield and rain does not touch you!!
untill you stop!

my car is a FLA. /TEXAS , rarely rains anyway, if the day shows incliment weather stays in garage!

but other day i had it out , and had to drive thru some dirty street, GOT MUD ON THE TIRES,!

some day i'm gonna build a CARSON removable top, aluminum frame ,fabric covering!
ron

 

Ye Gods man, mud on the tyres! How awful.
Did you require counselling?

 

SSHH!! i'm very sensitive about my money sucker!! LOL.
ron

 

In reference to Rambros picture#4 above. I had a 1966? 2+2 E type in Denver (Mile High) with air, that I could never bring into normal temp. Finally hung a racing oil cooler in the number 3 slot behind the radiator, condenser and then the cooler. The piping was through the large oil filter an back again, as I remember. 3/4 inch hosing because the six pumped 30 gals per minute. The cooler looked very similar to Ranbros's. The results were dramatic. Normal temperature, with air, in slow or stopped traffic. It was explained to me that the six was a thermosiphon engine and cooled primarily by oil. Its been a long time ago, but I do remember the filter was a large removable can that I braised a fitting to and then went back to a place near the filter that took a fitting without braising. I am unsure of the car build year, but I know the motor was a 4 Liter.

 

thanks for the info my new handle,, RAMBRO instead of Ronbros,, my wife got a kick out of that!!