Most Jaguar owners have been challenged with cooling system problems at one time or another. This is the first installment on a planned library of information about cooling systems. While aftermarket fans are hardly the place I would choose to start this series, many people seem to be in the process of installing better fans with the onset of summer, so it would seem to be timely.

In this series, I will attempt to explain how to get the most out of each component of your cooling system: pump, fan, radiator, coolant, and the engine itself. Engineering a cooling system requires taking the specification of all of these components into account, because changing anything affects everything else. But one of the easiest things to change is the cooling fan. Jaguar used many different types of fans over the years, from the solid aluminum fans of the early XK's, to the early electric fans used in the sixties, to belt driven fans with thermostatic clutches, and finally modern electric fans. There is no doubt that if your Jaguar has a cooling problem (and many early ones do), improving the fan is a major benefit.

Let's take a look at a few designs. The earliest XK's used solid aluminum fans. These were pure eye candy, among the prettiest engine fans every installed. They were terrible at their intended purpose, however. First of all, they were rather heavy castings. This placed a lot of drag on the motor, and strains the water pump bearings, neither of which is desireable. Second, the blades were fixed. There are several problems with this. First of all, airflow increases with engine speed, but generally, you don't need a fan when the car is moving over 30 MPH or so. So they represent useless drag at speed.  Another problem is that a  fixed fan has an upper speed limit, beyond which it stalls, which is to say that it can't produce additional airflow. The only way to make fixed fans acceptable at high RPM is to compromise the design so that less airflow is produced at low RPM, but that's when you need it most.

The next improvement was the electric fan. Early electrics, as used on the E-Type and some other XK-engined cars in the 60's, used a Lucas motor coupled to a two bladed steel propellor. Fan operation was controlled by a thermostat called an "Otter" switch. Since fan operation was totally independent of engine speed, operation was optimized, and drag reduced. The fan always operates below the peak speed of the blade, so that the maximum airflow is produced whenever required. But thanks to the Otter, the fan stops when not required. (In theory). The problems with these early installations are many. The motors are too weak, both in terms of power output and physical strength. As a result, fan capacity is limited, my tables below tell the tale: an early E-Type fan would move less than 600 CFM at most, while the later double fans would only move about 1300-1600CFM in total. Furthermore, because the bearings are marginal for the application, it's not unusual for the fan to wobble and vibrate. As alternators were introduced, it became possible to use more powerful fan motors, and to have more than one fan.The introduction of lighter plastic fans also helped.

The next iteration is the thermostatic clutch driven fan. These fans are powered by a belt, as the early XK fans were. But a thermostatic clutch allows the blade to freewheel when fan airflow isn't required. The blades are generally pressed steel, and are lighter than the old cast aluminum fans. Where room allows, these fans provide efficient cooling without taxing the electrical system.

Finally, modern electric fans provide much greater aiflow with reduced power consumption. This is achieved with efficient permanent magnet motors and very light plastic or metallic blades, with advanced aerodynamic designs. Current OEM fans are essentially identical to the commonly available aftermarket fans, but be careful about mounting points, which are usually unique to each model.

If you are selecting an aftermarket fan, there are several things to consider:

• More airflow always makes for better cooling, but it doesn't necessarily make up for deficiencies elsewhere in the cooling system. Jaguar cooling systems are generally airflow deficient.
• I think that horsepower, rather than cylinders or displacement, is the best way to estimate airflow requirements. Figure at least 600CFM for every 100 true horsepower, given the typical Jaguar cooling system. More is better.
• Diameter of the blade. If you are fitting a fan to an existing shroud, then the measurement is obvious, and crucial. The stock fan probably fit the shroud with a half inch of clearance or less, you want as good a fit. If you are working with a new application, try to find a fan which covers as much radiator area as possible. This is more important than improving total airflow. Concentrating airflow in a portion of the radiator is relatively ineffective.
• Current draw. If you have an older Jag, you may have limited current to work with. Be sure you have enough power for the fan you choose.
• Efficiency. The measure I use for fan efficiency is CFM/Amp, which tells you how much air flow you get for every amp you are consuming. Note that very high efficiency fans aren't always best for high speed performance: in some cases, the design of the blades can present greater air resistance when freewheeling. It's hard to tell what will work for a given application, so weigh your choices carefully and go with the best information you can get.
• Shrouding. Most plastic fans can operate without a separate shroud, some can't. It's always preferable to use a shroud.
• Mounting. Many aftermarket fans are "laced" directly to the radiator core. I am of the opinion that it's a poor way to mount a fan. Look for fans that can be mounted to the radiator frame or to the body of the car. You may have to fabricate suitable mounting hardware for your application.
• Push or pull. The fan can be mounted in front of the radiator or behind it. Mounting in front is generally less efficient, because it's not possible to build a proper shroud. Many aftermarket fans are reversible, but some are not. If you plan to mount the fan in front of the radiator, reduce the manufacturer's ratings by 20%.
• Thermostat. The Jaguar Otter switch is an odd thing, some of them work great, and then there are the others. Most manufactures have thermostatic switches of one sort or another, and in general, anyone's thermostat will work with anyone else's fan. There are three common ways aftermarket thermostats are mounted: 1) a probe which fits between the radiator fins is the simplest, but least accurate.  2) A probe which fits into a radiator hose, wires are thin enough to pass under the hose clamp without leakage. These are accurate, but I'm not crazy about the mounting. 3) A probe which fits into a tapped hole in the intake manifold. These are the best, but obviously not easy to install. Thermostats either activate at fixed temperature or variable temperature. In all cases, the hysteresis, or allowed variation in water temperature, is about 10F.
• Relay. Always use a fan relay. Directly wiring your fan through the thermostat will limit the life of your thermostat. I'm also not crazy about manual switches (except for racers), don't try to do a job by hand that's better done by a machine. Racers, of course, should only use a fan on the grid, and should switch off as soon as the race begins.
• Check the numbers. The table below summarizes all the current info available to me from the manufacturer's literature. Manufacturers specs vary with time, and there are no standard measurement techniques. Most manufacturers supply "free air flow" or zero static pressure CFM measurements, which may not have meaning in real world situations. So use the numbers as a guideline only. I take no responsibility for the accuracy of this data: you are encouraged to follow the links to the various sites and do your own research.
• Updates requested. E-mail me with any changes or additions.

Manufacturer	Model	Size	Thickness	Weight	CFM	Amps	CFM/Amp	Thermostat	Notes
Davies Craig	DCSL12LP	4.5"	1.5"	2.6lb	700	7	100
SPAL	30100286-7	5.2"	3.86"	1.1lb	248	2	124	available
Davies Craig	DCASP	5.5"	1"	1.9lb	800	6.5	123.1
Davies Craig	DCAX	5.5"	1"	1.9lb	900	7	128.6
SPAL	30100291-2	5.6"	3.86"	1.1lb	295	2.5	118	available
Kenlowe	6"-2000	6"	1"		298	3.6	82.8
Davies Craig	DCSL14LP	6"	1.5"	2.8lb	875	7.5	116.7	available
Tripac	14-E0167S1	6.5"	2.32"	1.7lb	306	3.9	78.5	available
SPAL	30100402-3	6.5"	2.05"	1.8lb	330	6.3	52.4	available
Tripac	14-E5167S1	6.5"	2.32"	1.7lb	411	5.6	73.4	available
Davies Craig	DC31	6.5"	1.5"	3.3lb	1550	11	140.9
Ron Davis		7"			1054	7.3	144.4
Tripac	14-E0190S1	7.5"	2.32"	1.9lb	360	3.6	100.0	Available
SPAL	30100358/393	7.5"	2.05"	2lb	440	5	88	available
Tripac	14-E5190S1	7.5"	2.55"	1.6lb	558	4.5	124.0	available
Davies Craig	DCSL8	8"	1"	1.9lb	400	5	80
Kenlowe	8"-2000	8"	1"		590	3.9	151.3
Perma-Cool	19128	8"	2.25"		800	4.5	177.8	available
Flex a Lite	365	8.5"x8.5"	2.5"		1600	16	100	available
Davies Craig	DCSL9	9"	1.2"	2lb	450	6.25	72
Tripac	14-4009S1	9"	2.38"	2lb	540	5.2	103.8	available
Asset	K9	9"	2.41"	2lb	570	5.4	105.6	available
SPAL	30100392/381	9"	2.05"	2.2lb	590	6	98.3	available
Tripac	14-4010S1	9"	2.69"	2lb	600	5	120.0	available
Mr Gasket	1984	9"	3.2"		700	5.5	127.3	available
SPAL	30100183-4	9"	3.7"	4.8lb	740	8	92.5	available
Jaguar	Series II E-Type	10"	5"	3lb	647	6.8	95.1	Otter	Stock
SPAL	30100360/374	10"	2.05"	22lb	650	6.4	101.6	available
Hayden	3670	10"	2.5"		650	5.4	120.4	available
Asset	14-4110B1	10"	2.41"	2.6lb	650	5.3	122.6	available
Derale	16510	10"	2.6"		650	5.3	122.6	available
Davies Craig	DCSL10	10"	1.2"	2.5lb	675	7	96.4
Hayden	3638 (sealed)	10"	5.625"		687	6.9	99.6	available
Kenlowe	10"-2000	10"	2.2"		705	6	117.5
Hayden	3630	10"	4.625"		715	7.8	91.7	available
Flex a Lite	108	10"	2.75"		800	6.5	123.1	available
Flex a Lite	50 or 55	10"	5.25"		850	7	121.4	available
Perma-Cool	19120	10"	2.25"		900	7	128.6	available
Mr Gasket	1985	10"	3.09"		950	8.3	114.5	available
CoolCat	CoolCat10	10"	5"	3lb	950	3.5	271.4	Otter	E -Type Compatible
SPAL	30100181-2	10"	3.7"	4.8lb	1070	10	107	available
Ron Davis		10"		2.0lb	1181	8.5	138.9
Perma-Cool	19010	10"	2.5"		1250	6.8	183.8	available
Vintage Air	32100-VUF	10"	3.125"		1251			available
Vintage Air	32610-VUF	10"	2.625"		1438			available
Flex a Lite	310	10"x10"	4.125"		1800	15	120	yes
Flex a Lite	320	10"x10"	4.125"		1800	15	120	available
V12s		10"x10"x10"x10"			5800	34	170.6	included	XJS Compatible
Tripac	14-6011R	11"	2.76"	3.1lb	680	5	136.0	Available
Jaguar	Series III E-Type	11"	5"	3lb	800	7.5	106.7	Otter	Stock
SPAL	30100364-5	11"	2.05"	2.5lb	810	6.8	119.1	available
Tripac	14-4311S1	11"	2.71"	2.4lb	820	6.3	130.2	available
Tripac	14-4011S1	11"	2.48"	2.4lb	875	8.5	102.9	available
Asset	14-4111B1	11"	2.44"	2.6lb	880	8.8	100	available
Derale	16512	11"	2.44"		880	8.8	100	available
SPAL	30101500-2	11"	2.48"	3.3lb	970	8.3	116.9	available
Tripac	14-4211S1	11"	3.22"	3.4lb	1090	10.1	107.9	available
SPAL	30100177-8	11"	3.7"	5.2lb	1390	12.5	111.2	available
Tripac	14-2X6011R	11"x11"	3.49"	6.3lb	1360	10	136.0	available
Tripac	14-2X311S1	11"x11"	2.65"	6.9lb	1750	17	102.9	available
Tripac	14-2X111S1	11"x11"	2.65"	6.9lb	1750	17	102.9	available
Tripac	14-2X111S2	11"x11"	3.39"	7.7lb	2180	20.2	107.9	available
SPAL	30100846	11"x11"	4.25"	10.6lb	2780	25	111.2	available
Hayden	3680	12"	2.625"		850	8.3	102.4	available
SPAL	30100375/384	12"	2.05"	2.5lb	870	7	124.3	available
Davies Craig	DCSL12	12"	1"	3.2lb	900	9	100
Hayden	3648 (sealed)	12"	5.625"		980	7.9	124.1	available
Hayden	3640	12"	4.625"		1050	10.5	100.0	available
Flex a Lite	10 or 20	12"	5.25"		1050	9	116.7	available
Flex a Lite	112	12"	2.875"		1050	9	116.7	available
Perma-Cool	19122	12"	2.75"		1200	6	200	available
SPAL	30101504-5	12"	2.48"	3.3lb	1230	11.8	104.2	available
Flex a Lite	125	12"	2.75"		1250	10	125	available
Flex a Lite	110/130	12"	2.625"		1250	9.5	131.6	yes
Flex a Lite	120/140	12"	2.625"		1250	9.5	131.6	available
SPAL	30100439/822	12"	3.39"	5.1lb	1360	14.5	93.8	available
Mr Gasket	1986	12"	3.09"		1400	10.2	137.3	available
V12s		12"			1500	8.8	170.5	XJS  std.	XJS Aux Fan
Vintage Air	32200-VUF	12"	3.125"		1540			available
Ron Davis		12"			1576	9	175.1
SPAL	30100175-6	12"	3.7"	5.4lb	1630	13.5	120.7	available
Perma-Cool	19008	12"	3.75"		1650	7.5	220	available
Vintage Air	32612-VUF	12"	2.625"		1771			available
Derale	16812	12"x12"	2.7"		1360	10.6	128.3	available
Flex a Lite	225/325	12"x12"	2.625"		2000	19.25	103.9	available
Flex a Lite	210/230	12"x12"	2.625"		2500	19.5	128.2	yes
Flex a Lite	220/240	12"x12"	2.625"		2500	19.5	128.2	available
Flex a Lite	575/675	12"x12"	2.625"		2500	19.5	128.2	yes
SPAL	30100398-9	13"	2.05"	2.5lb	920	6.7	137.3	available
Tripac	14-6213R	13"	3.19"	5.3lb	1137	11.7	97.2	available
Kenlowe	13"-2000	13"	3"		1170	11.7	100
Tripac	14-4213S3	13"	3.34"	3.9lb	1250	9.8	127.6	available
SPAL	30101507-8	13"	2.48"	3.3lb	1250	9.7	128.9	available
Tripac	14-6413R	13"	3.19"	6.1lb	1328	25.1	52.9	available
Kenlowe	13"HD-2000	13"	3.9"		1328	24.2	54.9
Asset	4213B3	13"	3.66"	4lb	1350	10.5	128.6	available
Derale	16514	13"	3.25"		1350	10.5	128.6	available
SPAL	30100847/851	13"	3.39"	5.2lb	1710	13.5	126.7	available
Tripac	14-2X6213RA	13"x13"	3.19"	10.6lb	2274	23.4	97.2	available
Tripac	14-2X313S3	13"x13"	3.36"	10.1lb	2500	19.6	127.6	available
Tripac	14-2X6413RA	13"x13"	3.19"	12.2lb	2656	50.2	52.9	available
SPAL	30100382/5	14"	2.05"	2.9lb	960	6.5	147.7	available
Davies Craig	DCSL14	14"	1.25"	3.3lb	1100	11	100
Flex a Lite	314	14"	3.5"		1100	6	183.3	available
SPAL	30101509-10	14"	2.48"	3.7lb	1280	9.9	129.3	available
Hayden	3690	14"	3.75"		1325	9.8	135.2	available
Hayden	3650	14"	4.625"		1350	12.8	105.5	available
Flex a Lite	114	14"	3.25"		1350	9.5	142.1	available
Hayden	3658 (sealed)	14"	5.625"		1430	10.1	141.6	available
SPAL	30100248-9	14"	3.39"	5lb	1720	18.5	93	available
SPAL	30100119-20	14"	3.39"	5lb	1720	16.3	105.5	available
Vintage Air	32400-VUF	14"	3.125"		1722			available
Mr Gasket	1987	14"	3.4"		1800	10.3	174.8	available
Ron Davis		14"		3lb	1828	9.5	192.4
Vintage Air	32614-VUF	14"	3.000"		1980			available
Perma-Cool	19114	14"	3.75"		2950	9.5	310.5	available
V12s		14"x14"			4000	20	200.0	included	XJS  Compatible
V12s		14"x14"			4500	28	160.7	included	XJS  Compatible
Flex a Lite	250/260	14"x14"	4.5"		5200	30	173.3	yes
Perma-Cool	19124	15"	3.9375"		1650	8	206.3	available
Flex a Lite	30/35/40	15"	4.25"		1950	9.8	199	yes
Flex a Lite	475	15"	3.875"		2030	9	225.6	yes
Derale	16516	15"	3.9"		2175	18.4	118.2	available
Derale	16818	15"	4.5"		2380	19	125.3	available
Vintage Air	34317-VUF	15"	4.25"		2700			available
Flex a Lite	60/150/155/165	15"	4.25"		2800	13.9	201.4	yes
Flex a Lite	175	15"	4.25"		2800	13.9	201.4	yes
Flex a Lite	270/280	15"x15"	4.5"		5500	28	196.4	yes
Jaguar	Series I E-Type	16"	5"	3lb	585	6.5	90.0	Otter	Stock
Tripac	14-6216R	16"	3.19"	5.5lb	1137	11.7	97.2	available
SPAL	30100400-1	16"	2.05"	2.9lb	1300	7.5	173.3	available
Tripac	14-6416R	16"	3.19"	5.5lb	1328	25.1	52.9	available
Flex a Lite	316	16"	3.5"		1600	8	200	available
SPAL	30101516-7	16"	2.48"	2.9lb	1610	11	146.4	available
Hayden	3700	16"	3.825"		1700	13.7	124.1	available
Tripac	14-4016S7	16"	3.98"	5.7lb	1810	14.5	124.8	available
Hayden	3710	16"	4.25"		1825	17.6	103.7	available
Tripac	14-4016S8	16"	3.98"	5.7lb	1860	15.7	118.5	available
Mr Gasket	1988	16"	3.4"		2000	11.4	175.4	available
Flex a Lite	116	16"	3.25"		2000	11	181.8	available
Perma-Cool	19126	16"	3.25"		2000	8.9	224.7	available
SPAL	30100825/223	16"	3.39"	5.2lb	2070	17.4	119	available
CoolCat	CoolCat38	16"	5"	3lb	2077	6.5	319.5	Otter	E-Type Compatible
Vintage Air	32600-VUF	16"	3.125"		2101			available
Ron Davis		16"		3lb	2197	11.2	196.2
Davies Craig	DCSL16	16"	2"	6.6lb	2200	19	115.8
Asset	4016B9	16"	3.9"	5.7lb	2320	20.2	114.9	available
Kenlowe	16"-2000	16"	3.9"		2320	20.2	114.9
Tripac	14-4016S9	16"	3.98"	5.7lb	2320	19.7	117.8	available
SPAL	30100231/2	16"	3.39"	5.2lb	2360	21.6	109.3	available
Vintage Air	32616-VUF	16"	4.25"		2416			available
V12s		16"			2700	19.2	140.6	included	XJS Compatible
Vintage Air	32616-VUF HD	16"	4.25"		2700			available
Vintage Air	32381-VUF	16"	4.25"		2700			available
Perma-Cool	19115	16"	3.75"		2950	9.8	301.0	available
Tripac	14-2X6216RA	16"x16"	3.19"	11.3lb	2274	23.4	97.2	available
Tripac	14-2X6416RA	16"x16"	3.19"	11.3lb	2656	50.2	52.9	available
Perma-Cool	19117	17.75"	3.75"		2500	10.3	242.7	available
Flex a Lite	318	18"	3.5"		2100	10	210.0	available
Vintage Air	32018-VUF	18"	5.125"		3700			available

Click here for an Excel version of this table

Vendor Links

Flex-A-Lite

Asset Manufacturing

Davies Craig

Derale

Kenlowe

Spal

Perma-Cool

Mr Gasket

Ron Davis Radiators

Vintage Air

Hayden

CoolCat

Tripac

V12

About the author - Michael Frank is Vice President and Webmaster of the Jaguar Touring Club. His red 2+2 E-Type is a familiar sight at JCNA events in the Northeast. Currently, he is building a reproduction of the 1963 Cunningham Lightweight E-Type .

Updated : 11/12/2002