Assorted cooling questions

[RotoFlexible]

My S2 has an S3-style wide radiator. Engine is 1700cc, about 145hp, and the car is used for everything from commuting to (hopefully) track days.

Currently, I have an engine-driven fan (the ugly orange multi-bladed replacement for the original) and a thermostat that must be about 70C. It does a pretty good job of controlling the temperature. I would like to replace the engine-driven fan with an electric and fit a hotter thermostat, around 80C or 180F.

I can get a 9" fan that will fit well on the front of the radiator, with a capacity of about 570CFM. Is that enough? I may be able to fit two of them if need be.

For a thermostatic fan controller, I can get a unit with a "radiator probe" (fits through the fins of the radiator) or one with a probe that slips under the radiator hose into the coolant. There's no provision on the radiator for a thread-in sensor. Any experience with either of these types of probes?

Finally, I am in the process of fitting an oil cooler, as recommended by my engine builder. Searching the archives revealed an opinion from type26owner (of blessed memory) that the oil cooler is unneeded and even harmful - the oil is already over-cooled in the pan. I have no oil temp gauge so I can't tell if there is a problem. Any opinions?

Thanks in advance for your advice.

[memini55]

Andrew,

My son has a +2 which we rebuilt last summer before LOG and drove out and back with the narrow radiator, which was stock with a 180 sat. We had installed a 10" fan with the plastic pins that go thru core. We used the tube in the top rad hose and had it pushed into the top tank of radiator. This setup worked well but it was really hot on the long hual so we just reconditioned a wide unit and installed it and now we keep mid gauge temps most of the time.
The only trick to the tube in the top is the hose needs to be new and soft to get it to seal well.

On the LOG trip we did have some heat issues on the mountain climb and long highway runs and opened to the heat contol to help move water, which was a big help but not fun to ride on +90 weather with the heat on full. Drink lots of water!!

One more thing we have done is I put a higher lbs cap on radiator and added a fill housing and cap at normal presure in the top hose in front of stat housing. This is much easier to fill and watch levels of coolant.

Mark

[TomR]

I'm using an aluminum radiator in the nose of my S4 so its not directly comparable, but I decided on two fans of similar size to your single fan. I'm a heat transfer guy, so maybe it's overkill....

Tom

[bill308]

RotoFlexible,

Like TomR, I'm a heat transfer guy too.

I fitted capillary tube based sensor that slips under the radiator tube and has worked well.

My S2 Elan delivers maybe 135-140 bhp with big intake valves, mild porting, and modest compression ratio and is fitted with the stock radiator. The fan is only needed when stopped or in slow traffic. It is termostatically controlled with a manual overide switch so I can turn it on early if it appears I will be stuck in slow traffic for a long time. This system has been reliable and trouble free. My fan is supported by rods and blows through the radiator and positioned about 1/2-inch from the fin matrix.

An electric fan should be far supperior to the water pump mounted, OEM version, under worst case conditions. Sitting in traffic, at low engine revs, the water pump mounted fan can't be too effective. I say give it a try with one fan. If you need more cooling you could always add a second one or a single bigger one. I personally prefer one that keys on coolant temperature, rather one that keys on external fin matrix temperature.

Two fans would benefit low speed or no speed driving, but would likely reduce cooling at speed, but disrupting car velocity induced flow.

Blocking off bypass air flow at speed, flow around the perimeter of the radiator, would be helpful.

Bill

Bill

[types26/36]

[quote="RotoFlexible"]Finally, I am in the process of fitting an oil cooler, as recommended by my engine builder. Searching the archives revealed an opinion from type26owner (of blessed memory) that the oil cooler is unneeded and even harmful - the oil is already over-cooled in the pan. I have no oil temp gauge so I can't tell if there is a problem.quote]


Andrew,
When I fitted an oil cooler to my Seven I also fitted an oil-stat I dont remember what temps it operated at but they are available from Burtons in the U.K. https://www.burtonpower.com/product_mai ... thermostat
the site does not list the operating temp but you could contact them to find out.

[RotoFlexible]

Thanks for the replies, they are very helpful.

According to the Bean's catalog, the oil cooler adapter has a 165F thermostat built in. It also has a small bypass so there is some flow at lower temps. Bill (engine builder) says the oil needs to be 155F before running the engine hard, and it can go much hotter without damage to the oil or engine.

All I have to go on is the oil pressure, which drops significantly (but not dangerously) at idle and low speeds when the engine is hot.

The installation is on hold until I pick up a 6-point 1-1/8" socket so I can install the adapter to the oil pump. There isn't enough clearance for a 12-point.

[garyeanderson]

After spending a large amount of money on my S2 engine I didn't want to skimp on cooling. My S4 with the S3 wide radiator would peg the needle at the
drop of the throttle when it was warm. When I re-built 26/4597 I had the choice of one of the heavy Marsden units or to go aftermarket. I chose to go
with the after market Scirocco type unit. It was a nice fit in the front and I havent done the ducting to improve its effectiveness. The first conversion was
on the green S2 and the radiator was sourced from Smiths Radiator, the other two are from Griffen, on ordered from summit racing and the other
was ordered direct from Griffin with the radiator cap deleted from the radiator as its redundent and prevented the radiator from being placed where
I wanted it at the time. The white Coupe hasen't run yet but the green S2 has been on the road for 11 years and the yellow pre-airflow Coupe has been
running for 4. The mounting feet on the Griffen unit needed to be narrowed a bit to fit in between the the inner wheel well openings but it left enough
to put rubber feet under the mounts. The Smiths unit had the mounting pads behind the unit so it was a bit easier to fit.

[twincamman]

wellll looking at the nose intake area I decided the problem was just control and direction of the air flow as the volume was adequate ---- so I added a floor of aluminium to the area behind the grill to improve flow --------and mounted the oil cooler on dzuse fasteners to aid removal ---sides were added to the headlight area to create a tunnel effect directing air to the stock rad in the stock position --the fan is from a morgan my chum was throwing away [ the fan not the morgan] and is mounted in a home made pedestal mounted on the floor ---[were no cheap--were canny] the whole thing sucks very well ----[DOH]----ed

[msd1107]

There are two aspects to the cooling problem.

The first is airflow through the radiator. The stock setup with the air intake not ducted to the radiator loses most of the airflow potential that comes in through the air intake. The placement of the radiator does not allow for efficient exhaust of what ever heat is transferred from the radiator to the air stream. And an engine mounted fan is least effective at idle and absorbs power at high RPM when it is not needed.

Any electric fan with either temperature or manual activation is an improvement. There is air movement when the car stops.

Many Elan owners have done what Gary and TomR have done - install an aluminum radiator up in the nose. A fanatic would construct a duct from the intake in the nose to the radiator to get the most out of the air flow entering the car. With this setup, I suspect that only a small fan would be needed. Our heat transfer experts should be able to weigh in on this subject.

The other aspect of this over heating problem is water circulation. The standard water pump is the culprit here. At low RPM, it pumps very little water (meaning low possible heat rejection), and at high RPM it absorbs more horsepower (it is a square law device). Several owners have gone to the Davies-Craig electric water pump. This uses a controller to modulate the speed of the water pump so that at low water temperatures the water pump flows low volumes and at high water temperatures it flows high volumes. Together with a temperature controlled radiator fan, there are very few temperature problems. A side benefit is a small reduction in power absorbtion since the electric water pump draws a maximum of about .14HP (less at lower water temperatures).

Of course, none of this is stock, so if you want to remain stockish, the parts manual has parts numbers for a front of the radiator electric fan (rather small). I have used this for years (I removed the engine driven fan immediately). The worst time was when I got caught in a long traffic jam at 40+C when the water temperature got up into the oil pressure region, but for most of the rest of the time it mainly stayed below 100C.

David
1968 36/7988

[steveww]

See my solution at http://www.steveww.org/index.php?id=26

[Petter Hval]

Andrew
You shuld take into consideration that a sucking fan on the
back of the rad. is more efficient then a blower i the front.
Petter

[Keith Scarfe]

I too am thinking of doing this mod. I want to keep it as std as poss. I don't like the sensors that slip under the hose. Most I have seen have a water leak here. I found this while searching:
http://www.demon-tweeks.co.uk/products/ProductDetail.asp?cls=ROAD&pcode=GLOEFC25
Any one tried this. Good or bad. Must be good as it is rather expensive
I'll probably go for a blower fan in front of the rad. Rad in std position. Which make of fan. Pacet, Kenlowe.
What size (bore) is the standard top hose?

[robcall]

I don't like the sensors that slip under the hose. Most I have seen have a water leak here.

Hi Keith-are you using the grommet/sleeve the that tubing is placed into prior to fitting under the hose? I find this seals quite well.

[TomR]

"A fanatic would construct a duct from the intake in the nose to the radiator to get the most out of the air flow entering the car. "

Well, I did that plus the Al radiator and two good sucking 9" fans. I am also thinking hard about an electric water pump (although the comment on head DT and all-or-nothing flow was interesting - I'm thinking about it). Like I said - overkill. Of course, I'm hoping for 180+ from my 2L BD if I ever put it together...

Tom

[TomR]

"A fanatic would construct a duct from the intake in the nose to the radiator to get the most out of the air flow entering the car. "

Well, I did that plus the Al radiator and two good sucking 9" fans. I am also thinking hard about an electric water pump (although the comment on head DT and all-or-nothing flow was interesting - I'm thinking about it). Like I said - overkill. Of course, I'm hoping for 180+ from my 2L BD if I ever put it together...

Tom