Agreed. I have, in many other cars, used a lower rated thermostat to reduce engine temps and thus have the engines run leaner. This may create problems in a supercharged car, non? Too lean means knocking which is a terrible thing.....

 

Rocketsports Racing head engine builder Tony Gentilozzi, discussing modifications to the AJ133 engine in the new Jaguar XFR...the car that ran 225.675 MPH at the Bonneville Salt Flats:

" We've separated the intercooler and engine cooling circuits to cool the air charge down a little bit".

http://engineeringtv.com/blogs/etv/a...t-225-mph.aspx

 

I partially separated the two systems on my XJR/6. I'd say it helped but not a night and day difference.

What DID help, though, was adding a separate fan for the supercharger radiator. The difference is most apparent when driving in traffic.

When my supercharger pump failed (dramtic loss in power, by the way) I replaced it with a higher flow unit. Not much difference, if any, over the OEM pump.

I am in the process of adding two additional coolers/radiators and a second pump, and will then completely divorce the two systems. I'll let everyone know how it works out.

Cheers
DD

 

@JTO

It’s probably in the words "a little", maybe they would have just reached 224 mph without it. Imagine 6 miles flat out, even in Germany on the autobahn a difficult task. You know the 80/20 rule; it costs 20% to reach 80% performance, and 80% to get the last 20%.

If you need to squeeze out everything possible (and there were more changes than Rocketsports mentioned in the interview) to get every single mile/horse out, have probably a nice budget, and 40 days in a shop for yourself, then go for it I would say. I doubt however you will be able to measure the gains, maybe indeed if you could do a similar run like Rocketsports did.

IMO it is not worth doing the effort as previously mentioned, and I think you would agree if you have done some work on a SC car. There are just more things you can do first before which have a better effect, and these are already mentioned here (pending on how you use the power).

@Doug,
I would go for a bigger tank in the intercooler circuit that will give you much more reserve, especially for long power runs, where it will matter. Then also a higher flow pump will help, with a good radiator. Not sure if I understood right, but as long as the radiators are not behind one another than it sounds like an interesting setup. The larger the surface area and more airflow on the radiators will help.

Andre.

 

the s/c cooling on my s-type r seems to be working better than on the 98 xjr i had previously. after driving home from work in the xjr (about 15 minutes), the charge coolers would be WAY too hot to touch. I was about to separate the xjr's s/c cooling system because of that. A few days ago i did the same test with the str and the coolers are only get warm. I was quite surprised.

 

Okay, I'll forward Gentilozzi the message and see if he reponds.

 

I was bummed when I heard that the circuit was combined. I was under the impression that there would be a separate resivoir until I popped the hood on my str. I was hoping that it was separate so I could employ the killer chiller box that uses the ac system to cool the intercooler fluid to levels just above freezing. Maybe I'll have to look into this project someday.

With all the discussion, alcohol injection is going to do awesome on this car!!! I think this intercooler system is a joke.

 

It gets 400hp so it's hardly a joke. No reason you can't cool better, whether a separate circuit or bigger intercoolers or whatever.

 

The stock inter cooler system is excellent. You should try some things that have been mentioned to prove it to your self. The best test has already been mentioned. Go drive the STR and them feel or measure the inter coolers under the engine cover. I have found them to stay very cool. The fact that the two systems are connected did bother me until I did some more thinking and testing. They are only connected for pressure equalization NOT for fluid flow. Yes a small amount of fluid does cross over but it appears to not be very much.

The real question that needs to be answered is how to tell when the car gets heat soaked. Before the STR I was seriously considering a MB E55. This car suffers from severe heat soak and it strongly effects it's performance. No doubt when it cuts the power back! The engine software will reduce engine power after only a small amount of hard driving. The E55 guys have a good bit of upgrades because of this. Bigger pumps, bigger inter coolers, extra fans.

The Killer Chiller is a cool idea and is used a lot on Ford Lightning Pickups/Mustangs. Kind of a neat short term power boost. Like NOS but no tanks to fill. Have not heard much about it lately??

http://www.killerchiller.com/
.
.
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clubairth1 - now you have me worried as my STR intercoolers feel VERY hot! What sort of temperature do you mean by "very cool", please?

 

well I should say is not as hot as I expected?? I have NOT done any temperature measurements. Need to get a infared temp gun!!
.
.
.

 

I don't own one of those, either

The only temp probe I currently have goes up to 50C (122F), as I recall.

hmm, think my friend has a metal probe of some sort....

 

I'm new on here as I'm contemplating a purchased of a S-Type R . I've owned a liquid intercooled car for 24 years and that one has a completely seperated system.

A couple of questions about this one?

1. Does the circulation pump run fulltime?

2. Are there any other control mechanisms in the intercooler system?

3. Has Jaguar ever explained why they used a combined system such as this?

Thanks.

Bob S.

 

1.Yes
2.No
3.Can’t remember, but I think it is a smart way chosen from Jaguar and seems obvious to me from how the system works.

Please note:
The intercooler circuit works independently from the engine coolant circuit
There is only a small tube connecting the intercooler circuit with the engine coolant circuit AFTER the radiator, and the air bleed tube on top of the intercooler radiator to the coolant box.

Advantages imho: The intercooler circuit benefits from the higher pressure of the engine coolant circuit, and the plumping is cheaper/easier (for Jaguar).


I’ll try to explain what the possible additional heat can be by the interconnect. Conditions for the explanation below are after normal driving once everything has reached operating temps:

Outside temp 20 degrees Celsius
Intercooler circuit probably about 15 degrees higher (so 35 Celsius)
Engine coolant after radiator 60 Celsius (also on the high side, just a guess though).

As mentioned there is NO flow between the two circuits other than pressure equalization and some contamination, so all I can imagine is only some drops flowing over (/contamination) between the system, let’s say 1 cc per second to stay on the high side.
The intercooler flow is about 330cc per second.

This would mean the intercooler coolant temperature would get 0.07553 Degrees hotter.

 

that's not as bad as I thought.

 

I looked at a diagram this on here this morning and I thought the main radiator was shared so that input temp to the engine and intercooler would be the same. If so, I don't understand your theory on input temps. Did I read that diagram wrong?

Ok I took another look, my mistake.

So it's basically just a shared expansion tank between the two systems.

Hmmm, are there ever any issues with it seeming like the charge temp ever gets too cold in cold weather?

Thanks

Bob S.

 

I have given an example for a XKR (Classic version), and each jaguar model has a slightly different setup, though they all use the same principle.

"Too cold", mmmhhhh, sorry, eh no I don't think so. You will notice that in winter you will be able to get more power.

 

avos - good info, thanks.

Your details look right. The only thing I'd add is (as you know) that there's IAT2, i.e. a second intake air temperature sensor, which measures the air temp after it's been supercharged and (inter)cooled. Briefly, will throw codes if you mess with the SC too much and fail to cool enough extra.

IAT2 can be monitored using OBD but not by the ordinary (generic) tools, I believe. If anyone knows the tech details (mode 6 or whatever) then even an elm327 would likely do it - just let me know!

I'll have a go at measuring my intercooler temps when I get a chance (if I can borrow a probe or buy one cheap enough).

 

So are you saying that it continuously monitors the the performance of the inter-cooling system and if threshold conditions are reached it then causes the system to operate in reduced power mode or something like that?

BTW, yes I understand that cold weather produces more power but in earlier systems , not Jaguar and a long time ago, I have experienced conditions where the system wasn't flexible enough to deal with very cold charge temperatures adequately and I had to have a switch to turn off the circulation pump. This was a turbocharged system though and that's a different sort of beast. So I just wondered if there were any such anomalies in this setup. Thanks for the info guys.

Any issues with circulation pump life on these cars and how easy is it to get to the pump?

Bob S.

 

Yes. And may set one or more codes. At least one member had P1474. You can search on that if you want details.
Don't know about the life but the above member (WinterJag) found his intercooler pump may have been OK but may well have been faulty, as I recall. I think it's just rear of the bottom right of the radiators. Access to everything looks horrid due to lack of space and lots of hoses.