[xj-s] downflow radiator

XJ-S
1

In “the Book” Kirby waxes philosophical on the logic of a dual input
down flow radiator to eliminate the double pass and resulting
turbulance/pressure problems. All of the radiator shops I contacted
didn’t think they could get a core that wide. That was until I spoke
with Chad Orr at Griffin Radiator. He basically told me to send my
radiator as a model and he would build me a down flow radiator which
would fit and have two inputs/ one output. He quoted me around
$750-$1000. It would look stock and would have no pressure differential
problems. With tax time approaching this is not in my budget, but maybe
later. I suspect if there was more interest it might become a standard
item and the price would come down some. Just a little grist for the
mill
Tom Wilson 87 coupe

2

Yeah, when my stock radiator gives up I’m gonna try that.

Cheers,
BryOn Wed, 24 Jan 2001, Tom and Teresa Wilson wrote:

In “the Book” Kirby waxes philosophical on the logic of a dual input
down flow radiator to eliminate the double pass and resulting
turbulance/pressure problems. All of the radiator shops I contacted
didn’t think they could get a core that wide. That was until I spoke
with Chad Orr at Griffin Radiator. He basically told me to send my
radiator as a model and he would build me a down flow radiator which
would fit and have two inputs/ one output. He quoted me around
$750-$1000. It would look stock and would have no pressure differential
problems. With tax time approaching this is not in my budget, but maybe
later. I suspect if there was more interest it might become a standard
item and the price would come down some. Just a little grist for the
mill
Tom Wilson 87 coupe

3

Hey Bry: I have been running a single pass all-aluminum drip-in radiator and
twin SPAL fans plus some copper crossover plumbing for months now and the
results are tremendous. As far as I can see it eliminates the cooling
problem. The only thing I don’t know about the system is how
it reacts with the stock tranny. I continue to think that if we can get 10
really serious people to-gether and make an order we can get really good
prices on the radiators themselves. By the time that 10 of the radiators are
out there for a little bit of time the solution will be proven. Just a
thought. If anyone is truly interested they can contact me off-list and we
might be able to get things going. Bradley Smith, 1985 XJ-S coupe (Not your
father’s Jaguar!)

4

Am I the only person who thinks the double pass radiator is
perfectly OK and works as Jaguar intended?

Bernie>

On Wed, 24 Jan 2001, Tom and Teresa Wilson wrote:

In “the Book” Kirby waxes philosophical on the logic of a dual input
down flow radiator to eliminate the double pass and resulting
turbulance/pressure problems. All of the radiator shops I contacted
didn’t think they could get a core that wide. That was until I spoke
with Chad Orr at Griffin Radiator. He basically told me to send my
radiator as a model and he would build me a down flow radiator which
would fit and have two inputs/ one output. He quoted me around
$750-$1000. It would look stock and would have no pressure differential
problems. With tax time approaching this is not in my budget, but maybe
later. I suspect if there was more interest it might become a standard
item and the price would come down some. Just a little grist for the
mill
Tom Wilson 87 coupe

5

Actually…No?
I had an 88 Coupe with the original cooling system…with proper
maintenance…it was perfectly fine? I drove it through the hottest summer
months here in Florida, with the A/C blasting out cold air the whole time?
I just priced a direct replacement radiator for my 89 Convertible…is
was only $390 including shipping and sales tax?
I can’t see spending an extra $300-$400 for an aftermarket radiator…now
with some modifications to the drivetrain…it might warrant the
aftermarket. But if you go with a 5-speed conversion you should save some
drain on the cooling system?
Not for me…other mods first…

6

This is my third attempt at posting this message…I’m new to the
group…so apologies if you have already received this posting!

I’m wondering whether or not anyone else has ever had this problem with
their XJ-S convertible. Basically, I encounter a fairly severe buffeting
when I drive between approximately 85 MPH and 110 MPH…with the top
down! If the top is raised, the car is smooth as silk, and if I get faster
than 110 (we have long, empty roads here in Georgia!) it goes away. It is
definitely an aerodynamic phenomenon, as there is no vibration in the wheel,
and the cowl is not shaking. What happens is that as I approach 85, I can
start to hear the wind buffeting over the top of the windshield, and when I
hit 85 or so, it really kiks in, making my hair stand straight up!

I have done considrable suspension tuning to the car (new springs, shocks,
delrin bushings, etc.) and the car is slightly lowered (less than 1 inch),
and the front is slightly lower than the rear, due to the fact that I’m
running the shocks on the back with an adjustable ride height, and I need to
lower it by a tad. I’m hoping that might fix it, but it seems like a long
shot.

My question is this: Has anyone ever had this problem before, and do you
know why it is occurring. I’m in the process of doing aome body
modifications (spoiler kit, rear wing, etc.) and if there’s something I can
do now to get rid of this phenomenon, I’d like to try.

Suggestions?

Thanks,
C.Y. Smith
'89 XJ-S Convertible

7

Am I the only person who thinks the double pass
radiator is perfectly OK and works as Jaguar
intended?

Uh, no. My 1988 rad was rebuilt several years ago. I
haven’t been attentive with flushing. It’s never
given me any problems. I’ve never had any cooling
difficulties short of a thermostat or a fan relay
giving up. I’m not normally a lucky guy.

Dean Hubbard
Orlando, FL
1988 XJ-S (I’m stickin’ with the old.)From: Bernard Embden <bernie@embden.com

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8

Message text written by Bernard Embden

Am I the only person who thinks the double pass radiator is
perfectly OK and works as Jaguar intended?
<

No, you are not - but I think you might spark off a hot debate by saying
so.

I know for a fact that the V12 underwent proving trials at high ambient
temperatures in Nevada without any problems.

Roger Bywater.

9

Am I the only person who thinks the double pass radiator is
perfectly OK and works as Jaguar intended?
<

No, you are not - but I think you might spark off a hot debate by saying
so.

I think most people’s beef with the stock setup isn’t so much cooling
ability as it is the fact that you can only see the temperature of one
bank. Thus the other bank could overheat without much to show for it on
the gauge.

Cheers,
Bry

10

If you look in some of the popular auto magazines you will find a company
that makes a device for curing this problem,
they make them for many different cars and I think I have even seen the XJS
listed.

-Don Buresh, 1991 XJ-S V12 Coupe, Classic Edition----- Original Message -----
From: “C.Y. Smith” cysmith@zytex.com
To: “XJ-S” xj-s@jag-lovers.org
Sent: Thursday, January 25, 2001 10:19 AM
Subject: [xj-s] Convertible Buffeting

This is my third attempt at posting this message…I’m new to the
group…so apologies if you have already received this posting!

I’m wondering whether or not anyone else has ever had this problem with
their XJ-S convertible. Basically, I encounter a fairly severe buffeting
when I drive between approximately 85 MPH and 110 MPH…with the top
down! If the top is raised, the car is smooth as silk, and if I get
faster
than 110 (we have long, empty roads here in Georgia!) it goes away. It is
definitely an aerodynamic phenomenon, as there is no vibration in the
wheel,
and the cowl is not shaking. What happens is that as I approach 85, I can
start to hear the wind buffeting over the top of the windshield, and when
I
hit 85 or so, it really kiks in, making my hair stand straight up!

I have done considrable suspension tuning to the car (new springs, shocks,
delrin bushings, etc.) and the car is slightly lowered (less than 1 inch),
and the front is slightly lower than the rear, due to the fact that I’m
running the shocks on the back with an adjustable ride height, and I need
to
lower it by a tad. I’m hoping that might fix it, but it seems like a long
shot.

My question is this: Has anyone ever had this problem before, and do you
know why it is occurring. I’m in the process of doing aome body
modifications (spoiler kit, rear wing, etc.) and if there’s something I
can
do now to get rid of this phenomenon, I’d like to try.

Suggestions?

Thanks,
C.Y. Smith
'89 XJ-S Convertible

11

C.Y.,
I had a similar problem with my BMW 635Csi. What almost cured it was a cop
blue lighting me at 140mph! Then, when I got the drag racing ticket and they
suspended my license…that cured it! Haven’t driven the bmw in quite a
while. …But I have been upgrading the brakes and suspension on the XJC ;).
Bill Smith, on a long empty road in south Ga…
'75 XJC 350v8-----Original Message-----
From: Donald C. Buresh, Jr. dburesh@cfl.rr.com
To: C.Y. Smith cysmith@zytex.com; XJ-S xj-s@jag-lovers.org
Date: Thursday, January 25, 2001 6:51 PM
Subject: Re: [xj-s] Convertible Buffeting

If you look in some of the popular auto magazines you will find a company
that makes a device for curing this problem,
they make them for many different cars and I think I have even seen the XJS
listed.

-Don Buresh, 1991 XJ-S V12 Coupe, Classic Edition

----- Original Message -----
From: “C.Y. Smith” cysmith@zytex.com
To: “XJ-S” xj-s@jag-lovers.org
Sent: Thursday, January 25, 2001 10:19 AM
Subject: [xj-s] Convertible Buffeting

This is my third attempt at posting this message…I’m new to the
group…so apologies if you have already received this posting!

I’m wondering whether or not anyone else has ever had this problem with
their XJ-S convertible. Basically, I encounter a fairly severe buffeting
when I drive between approximately 85 MPH and 110 MPH…with the top
down! If the top is raised, the car is smooth as silk, and if I get
faster
than 110 (we have long, empty roads here in Georgia!) it goes away. It
is

definitely an aerodynamic phenomenon, as there is no vibration in the
wheel,
and the cowl is not shaking. What happens is that as I approach 85, I
can

start to hear the wind buffeting over the top of the windshield, and when
I
hit 85 or so, it really kiks in, making my hair stand straight up!

I have done considrable suspension tuning to the car (new springs,
shocks,

delrin bushings, etc.) and the car is slightly lowered (less than 1
inch),

and the front is slightly lower than the rear, due to the fact that I’m
running the shocks on the back with an adjustable ride height, and I need
to
lower it by a tad. I’m hoping that might fix it, but it seems like a
long

shot.

My question is this: Has anyone ever had this problem before, and do you
know why it is occurring. I’m in the process of doing aome body
modifications (spoiler kit, rear wing, etc.) and if there’s something I
can
do now to get rid of this phenomenon, I’d like to try.

Suggestions?

Thanks,
C.Y. Smith
'89 XJ-S Convertible

12

Hello Roger: I have been on this list for just about 4 years. Every year
during the months of April through September there are lengthy e-mail threads
that sometimes seem to run for weeks at a time concerning problems with the
stock cooling systems. Much of the problem owners have had with dropped
valve seats followed sessions of the engines being run at high temperatures
brought on by malfunctioning cooling systems. I don’t in any way mean this
as a “barb” aimed at you or England in general, as you must know we are all
delighted with having you as an active contributor to our forum and the
English cars are our passion, but the conditions here are considerably more
extreme in variation than are those in England. This doesn’t mean that the
stock cooling systems can’t deal with the heat of Florida or Texas or New
Orleans for a period of time…however after years of going through the
temperature extremes they simply wear out and the attempts to repair them
off-times don’t work as you would think.
This all happens with relatively stock XJ-Ss. I could go on and on with my
particular case but that would only bore you and everyone else who read it
however…For a total outlay of just about $1,600 give or take a few bucks
because they haven’t been merchandised yet the problem can be completely
vanquished. Gone, finito, over etc…not just for a normally configured XJ-S
V-12 but V-12s that have had their power outputs boosted. The system I am
talking about is not a high tech system but one with the right idea and
quality built in throughout the system. How can anyone disagree with
success. I ran the relatively stock cooling system with your AJ6 Torque plus
conversion and a few other goodies that put the hp at just about 375. The
weekest link in the chain was a rather dicey pair of electric fans rather
than the original belt-driven ones. Otherwise the system was stock. I even
had a fourth tier of cooling tubes put in the raditor. It just couldn’t keep
up with normal driving. AC coluld only be used on the highway. I constantly
had the smell of leaking boiling coolant, the temperatures simply rolled up
from the car bottom.
The changes we made were rather simple…1. A custom-designed all-aluminum
quality radiator that is built to stress air flow. 1" tubes in the body with
only two tiers (not 3 as so many try) with 10-11 vanes per inch of tube vs
13-15 vane in conventional repalcement rads. The intake to the radiator on
the driver left upper has been removed and only the return and a off-fitting
for a oil cooler/stabilizer left on the left side of the radiator. We have
re-routed the coolant from the left coolant manifold to go across the engine
block and join with the right bank in a larger than stock intake for the
upper right side of the radiator. This forces all the coolant to make an
entire pass through the entire radiator before being released into the block.
2. We used a pair of “unshrouded” SPAL 11" puller fans on the engine side
of the radiator with very high quality
electric controls working the thermostat. 3. We had fittings mounted in the
system for a cartridge-type prototype oil cooler that uses the coolant to
pass the oil and drain off the heat. 4.
We returned to four rows of 3 1/2" louvres on each side of the engine hood.
We also have a “power-bulge” running up the hood that gives quite a bit of
room for the circulation of air in the engine compartment. The end
result…As you know, because we have talked on the phone about it, we run
twin Whipple superchargers during the last dyno run we were putting out just
under 600 hp and 550 or so lbs of torque. During the last 3 months of
dyno-tuning and just straight idle/ rev high tuning, street speed runs etc.
With revs up to the 7,000 rpm mark and long-time idles etc. the temperature
gauge has never gone above the “N”. When we changed the boost from 9 to 10
lbs to 12 to 13.5 lbs the change in the surface and ambient temps were only
10 degrees. In short $1,600 approximately produced a bomb-proof cooling
system that should last for years and years with a minimum of maintenance.
It can do it at 275 hp and at 600 hp under seem-ingly all circumstances.
When you contrast the circumstances we generally have on our list during the
heat season from a great many “stock systems” (notice I didn’t say all) and
the experience we have had under the circumstances I described, it seems
that the single pass system does truly work and can absorb the extra degrees
brought about by boosted engine performance. We didn’t invent it for
sure…I saw much the same unit later on from a distance in the Group 44
cars. I would be amazed if you, or anyone, had followed along to this point
in this long E-mail but if you did I would appreciate yours or anyone else’s
comments on the system or principles. Bradley Smith, 1985 XJ-S coupe (Not
your father’s Jaguar!)

13

I live in North FLA (Tallahassee) and still have some tendency for the car
to run hot…
I never had a boil over…but with AC running…standing in traffic on a
hot day…the needle runs up.
I have had all new hoses…a new radiator (just like the old) flushed new
fan clutch…etc etc etc…
and I’m still not comfortable on long drives in the hottest months with the
AC on.
I doubt it’s the radiator…will probably go with an electric fan soon…
but it is nice to hear from others in FLA who DON’T have problems…That
gives me hope…!!!
(1998 XJS coupe)
Steve Haley>Uh, no. My 1988 rad was rebuilt several years ago. I

haven’t been attentive with flushing. It’s never
given me any problems. I’ve never had any cooling
difficulties short of a thermostat or a fan relay
giving up. I’m not normally a lucky guy.

Dean Hubbard
Orlando, FL
1988 XJ-S (I’m stickin’ with the old.)

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Yahoo! Auctions - Buy the things you want at great prices.
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14

Some time back…there was a web page posted with pictures and descriptions
about how to put a GM radiator onto the main radiator shroud…along with,
as I recall, a BMW or Audi thermostatic switch on the hose…
Is this web page still up?
I’m looking for the numbers, I have the pictures…but have lost the text…
Thanks lots…
Stephen…

15

Stephen,
Do you mean a GM fan? And a Saab thermostatic switch?
If so, check my page at
www.mts.net/~aheartfd
Do you want the 82 Saab 900T less switch :slight_smile: ?
Alan
90 XJ40
85 XJS TWR> -----Original Message-----

From: owner-xj-s@jag-lovers.org [mailto:owner-xj-s@jag-lovers.org]On
Behalf Of Cool?hade
Sent: Friday, March 09, 2001 11:14 PM
To: XJ-S Digest
Subject: [xj-s] GM radiator conversion for xjs

Some time back…there was a web page posted with pictures and
descriptions
about how to put a GM radiator onto the main radiator
shroud…along with,
as I recall, a BMW or Audi thermostatic switch on the hose…
Is this web page still up?
I’m looking for the numbers, I have the pictures…but have lost
the text…
Thanks lots…
Stephen…

16

At 12:49 PM 3/11/01 -0600, Alan Heartfield wrote:

Stephen,
Do you mean a GM fan? And a Saab thermostatic switch?
If so, check my page at

Alan…or anyone else who knows
Regarding the GM fan that fits the bolts on the XJS shroud…
The numbers on the fan are hard to read…and they don’t look like part
numbers…
If you have the actual part number…or -perhaps the make and model of the
donor car, that might help…
The mechanic can’t tell from the picture which it is…
Thanks
Steve

17

The wrecker told me it was from a Camaro. Kirby denies this. I myself know
nothing about Detroit products, so can’t say.
I seem to remember having to make new bolt holes. No big deal. The shroud
is canted anyway, so you have to modify it to make any fan sit square to the
shroud.

Alan.> -----Original Message-----

From: owner-xj-s@jag-lovers.org [mailto:owner-xj-s@jag-lovers.org]On
Behalf Of Cool?hade
Sent: Monday, March 12, 2001 4:45 PM
To: Alan Heartfield; Xj-S
Subject: RE: [xj-s] GM radiator conversion for xjs

At 12:49 PM 3/11/01 -0600, Alan Heartfield wrote:

Stephen,
Do you mean a GM fan? And a Saab thermostatic switch?
If so, check my page at

Alan…or anyone else who knows
Regarding the GM fan that fits the bolts on the XJS shroud…
The numbers on the fan are hard to read…and they don’t look like part
numbers…
If you have the actual part number…or -perhaps the make and
model of the
donor car, that might help…
The mechanic can’t tell from the picture which it is…
Thanks
Steve

18

The wrecker told me it was from a Camaro. Kirby denies this.

Moi? Negatory! My brother owns a 2000 Camaro, and reports that they
do, in fact, have an electric fan. If it has one, it’s gotta be a
big one. This summer I plan to visit my bro, may take a look at that
fan for myself.

The shroud is
canted anyway, so you have to modify it to make any fan sit square to
the shroud.

Hey, maybe canted is good! Maybe we can figure out how to use that
to our advantage.

– KirbertOn 15 Mar 2001, at 17:56, Alan Heartfield wrote:

19

At 12:05 AM 3/16/01 -0500, Kirbert wrote:>On 15 Mar 2001, at 17:56, Alan Heartfield wrote:

The wrecker told me it was from a Camaro. Kirby denies this.

Moi? Negatory! My brother owns a 2000 Camaro, and reports that they
do, in fact, have an electric fan. If it has one, it’s gotta be a
big one. This summer I plan to visit my bro, may take a look at that
fan for myself.

The shroud is
canted anyway, so you have to modify it to make any fan sit square to
the shroud.

Hey, maybe canted is good! Maybe we can figure out how to use that
to our advantage.

– Kirbert

My mechanic says that the radiator fan that fits the transverse mounted
LATE Toronado, Buick Regal/Lesabre
should work…and fit with only the minor adjustment. He called around a
lot of places to find this out .
Does this sound right to anyone??

Steve

20

My mechanic says that the radiator fan that fits the transverse
mounted LATE Toronado, Buick Regal/Lesabre should work…and fit with
only the minor adjustment. He called around a lot of places to find
this out . Does this sound right to anyone??

That’s the one in my car! There’s a pic on the jag-lovers.org/xj-
s/book page.

– KirbertOn 16 Mar 2001, at 19:52, �ool�hade wrote: