so im looking at options for a radiator upgrade and summit racing sells a single pass aluminum radiator for 200 cheaper than the standard aluminum double.pass, is this worth it?

 

You will spend the $200 getting it to fit with Xover pipes etc.

There is nothing wrong with the Standard XJS radiator for cooling a road car. By all means go alloy but if your standard radiator is good keep it. I would add a good quality oil cooler.

I have removed ALL of the metal lower sill panels on the front of my car and I have a TWR front bar. There is loads of room for a large oil cooler in there now.

EDIT... ALL racing teams run multiple pass radiators (if the rules allow) as they are far better at cooling than a single pass. I got this from a guy here in Aus that builds most of the radiators for the burnout competition cars, these are 3 pass.

 

Are you talking about the Becool brand radiator from Summit? I recently finished installing one in my car and, generally, would agree with Warren - for me making it fit with the v12 was a ton of extra work - (I believe it may be intended for use with a v8 engine swap) - a more skilled mechanic could probably do it more easily though.

I don't want to give the wrong impression about the radiator itself though - as far as I can tell it seems to be very well made, and when I called Becool with a couple questions the guys there were very knowledgeable and helpful.

The difficulties I had were: plumbing the two engine outlets into one radiator inlet - nothing high tech but a lot of fiddling around and not much space to do it in. The new radiator didn't have the same fittings as stock for the trans cooler hoses - Jaguar used something that, at least today, is pretty uncommon and hard to find around here. The new radiator's mounting studs fit perfectly, but the rad itself is a bit thicker (front to back) which required altering the mounting for the fan shroud - might not be an issue if not using the stock fan setup. One more small glitch - the new radiator has a drain petcock - which would seem like a good thing - but the stock fan shroud is so close to it that it can't be turned or, in my case, closed (I replaced it with a pipe plug).

Regarding price, I did probably spend close to $200 in parts and materials to make it fit.

If I were to do it again I would get the original radiator repaired/recored (I replaced it because it was leaking on both sides where the core met the tanks). I'm confident a stock radiator in good condition would be fine for my stock engine. A modified engine might need more though I guess.

Hope this helps you, Eric

 

I have seen a 600hp twin turbo V12 XJS running a stock radiator. The problem is not the original radiator. There are a few things you can do to increase the cooling capacity.

One big problem is the lack of air flow under the bonnet. The XJS has a rubber seal across the rear between the bonnet and the body, get rid of this and if possible take the flange off to allow air to flow from the rear of the engine bay.

If air can not flow through the bay it can not flow through the radiator, for example if you totally sealed the engine bay except for the radiator grille there is going to little to no flow through the radiator.

 

i have removed that seal, how do I keep water from coming in if u remove the lip?

 

I would not worry too much about the water, you would get more water through bonnet vents while stationary.

If you are really worried you could lift the rear of the bonnet slightly, would require adjusting the catches up slightly.

I was reading in Allan's book that the Group A XJS had hood pin failure due to the buildup of air pressure under the bonnet. Shows how well sealed it is.

 

BECOOL actually has the blue-prints to make a radiator specifically for our XJS, and they have done so several times. However, Brass is much more efficient at dissipating heat than is aluminum, and, because of that fact, I will keep my stock radiators in my Jags. The whole reason aluminum radiators came into being is because they are lighter, and cheaper to manufacture than their brass counterparts. I see little point in spending good money to put a lighter, cheaply manufactured radiator in a 2-ton luxury GT.

 

i use a stock radiator in mine, NO overheat at all, and it gets to 100-105 around here quite often.
car runs 180-185F , modded the kooling system using just logical methods.

Cal Question; if you are going to show everyone how to build a 500hp Jag V12, why so many questions addressed to most on this thread?
seems as tho they are helping you do the knowledge and engineering!

 

when i was building my car and engine ,drive system,1993-1995 there was no internet or just about nothing for a modded Jag V12, everything had to be done with just simple logic, and hoped it would work. no such thing as an over the counter aluminum radiator, yes could be custom made for $1200-1400.

i did have some communication with grp 44 but it was not all that forth coming,with knowledge. tullius was not happy with Jaguar and TWR at that time! if you read in the Allen Scott book TW was a pretty ruthless and hard working person.

race cams for a Jaguar V12? companies just laughed, and said no not available.

my cams had to be custom ground,one off, at Crane cams in Daytona FL. i was LUCKY enough to know some engineers there, they took my stock cams,and run them on a cam profiling machine, put the info on a disc,run it thru a computor comparision program,(didnt even know anything like that exsisted) and then found some cores(i dont know where), and made a nice set of performance oriented race cams.

had the covers off couple months ago, all is perfect inside, 18yrs and counting!

 

and this is how this guy did it! letting the hot air out from under the hood!