Twincam running to cold?

Hi
I have been using my +2 this week and have noticed it is not getting up to its usual running temp. During the summer it was at about 90 degrees but in this cold weather will not go above 80. I have adjusted the kenlow so that it doesn’t come on at all when the car is moving.
Should I be looking at thermostats?
Chris

  • I wouldn’t worry abt. 80 deg, unless you feel that your heater does not deliver enough hot air…( - if so, go for a warmer thermostat , but watch out when spring comes…)

Dag

Chris,

Which radiator is fitted? Is it the smaller one with the small ‘wings’ at the side?

If so, I think this is a symptom of the rad being pretty near it’s limit in the summer time which is why the temp is up around 90deg. What happens in traffic or at junctions when you are stopped? Does the fan cut in quickly?
I have the smaller rad which I had recored last year (with a Triumph 2.5pi type core, as advised by the radiator repair chap) and the temp sounds very similar to yours. I have an 82 deg thermostat fitted but the temp rarely goes above 80 deg on the open road in Winter. Stopped in traffic? then 90 deg appears pretty quickly and the fan cuts in.
The heater is also nice and warm.

I’m still not convinced I have the right radiator and am eying one of these full width alloy jobs as I’m planing some longer trips this year in the Summer. I don’t to be one of these people stopped by the side of the road emitting more steam than a good going traction engine! :blush:

Happy new year, by the way.

Regards,

Hamish.

Hey Chris,
Your engine is just obeying the laws of thermodynamics. I have to add a panel onto the front grill to reduce the airflow on colder days. I velcro a 40sq/in aluminum sheet so it can be removed easily. It’s still a pain when I forget to deal with it since I’m strapped in when I remember. My choke cable which has no purpose anymore and is going to be used to flip that panel up and down REAL soon from the cockpit. Brrrr… the damn heater does not put out much heat too. It’s a blast furnace when things are corrected. :laughing:

Since the search capability is working on this forum again you should go back and read the stuff I posted on the cooling system. Lotus did the minimum in this area. It can be corrected quite easily though. I have lots of experience in heatflow of x-ray optics devices. To fix and understand the issues of the Elan cooling is a not all that hard. Most people do exactly the wrong things to correct the problems due to ignorance. Most of the info posted by non-engineers on the web is simply flatout wrong.

heaters??? in California —my SUPER 7 doesn’t even have one ----you So cal Dudes are getting soft --whats cold there 50 degrees f??? :laughing: ED

Hey Ed,
I admit it, I’m a wimp and hate to be cold. On the otherhand, I get to drive my Elan all the time. The highpoint of every working day is the drive to and from. :stuck_out_tongue:

Back when I had little kiddies that had to be dropped off at school I could only afford a 56 VW bug with no heater and no headliner. My son would take great delight in directing the condensation which would form on the inside of the roof so it would drip on my head. Now that was a miseable car to drive in the winter. :imp:

Iwish I could drive it all year but the Snow and ice high points the car and the salt dissolves the 18 guage steel chassis in about a week -and the cold makes the fiber glass so brittle it cracks or breaks —I’M just jealous of your fine so cal weather --we have 11 months of winter and one month of poor snow shoeing here :cry: -ed

I’ve got a cozy warm cockpit in just three miles now. :smiley:

i had a V.W. 59 bug-----i WAS NOT EVER WARM IN THE THING---- the condensation simply froze inside till spring --my sons mini had what he called ’ English heat’ —one degree above ambient ----Oh Canada—why wasn’t the border set at the 50th parallel ?—ED :sunglasses: [ NOMEX ON ]

Hey, now that I’m thinking about it here’s a tip I bet most folks have not picked up on. The knob on the heater cable locks into that position when it’s rotated oneway or the other by about 90 degrees.

I put a hunking big return spring on the shutoff valve now that I can expire from being overheated. The damn thing could not be throttled back enough without popping open the bonnet and forcing it closed by hand.

It’s the big aluminum head that overcools the engine with the amount of airflow swooshing by it in colder weather. Try this experiment and see for yourself. Wrap the head loosely with aluminum cooling foil being careful not to short out the spark plug wires. The idea is to slowdown the convection cooling rate. The engine will heat up another 10C at least.

This the first car I’ve ever seen that both overcools and overheats! Nice work Lotus. :imp:

Overcooling is fixed by reducing the airflow. Overheating is fixed by by operating the engine between 90-105C and installing dual fans on the radiator that will force at the very minimum 1000 cfm. Installing just one fan without a shroud will not do it. Every square inch of the core must have air force fed through it. When this is done correctly the stock radiator has enough cooling rate so it can be operated at WOT on the racetrack on a sweltering 45C day. It gets mighty hot at Thunderhill racetrack.

Don’t install an oil cooler either because the Elan is known to overcool it’s oilpan. All oil manufacturers recommend the oil heatup to at least 190F to drive off the blowby. The Elan only gets it to 150F typically. If your engine oil turns black quickly after an oil change, that’s the reason why.

Would you suggest reducing the airflow at the grill by blanking a part off or covering part of the rad to reduce its effectiveness? I didn’t notice any serious overheating in the summer, the single fan adjusted to come on early seemed to keep that under control.
Chris

Chris,
Try a piece of paper on the front grill which 2" x 20" or = 40sq/in. If you put it on the radiator it will do no good. No water circuits through the radiator until the thermostat opens. The convection cooling directly from the head at partial throttle is so high that the thermostat is not even opening. Honest to gawd this is what is happening when the ambient temperature gets down to 10C or below. Blew me away when I realized this!

Too bad Mike Causer does not post here. He’s the only other engineer that has confirmed my diagnosis. His situation is even worse because on his later Elite he also gets carburetor icing. That would really suck!

Keith
This cooling via the head is all well and good but what is the route for this cooling air stream?
Surely if it has a route it can be reduced?

John :wink:

I can now see that reducing airflow at the grill is what is needed but paper or card put over it will cover the number plate letters. I am thinking of making up a perspex sheet to completely fill the hole and then drilling large holes in it to allow the correct amount of airflow, I will experiment with this. I really think it is running under working temp which can’t be good, especially as the oil already is to cool. ( Also my toes are not at working temp!).
I will post again when I have some results.
Chris

But 10 deg C is a typical english summer day :wink:

I don’t run my car right through the winter but I’m sure there are definitely days in the year when I’ve set off from home when it’s been around 10 deg C and had no problem getting the car warmed up.

After ripping a hole in my sump last year I had been considering a sumpguard of some description but I’m wondering if it might be worth considering a permanently fitted undertray that keeps up sump temperatures and restricts the airflow out of the engine bay (working along the lines that the most effective way to keep up engine temps on a single seater is to tape up the radiator exit ductwork - not the inlet)

John,
The airflow through the front drill. Whether it goes through the radiator core or around the outside it matters diddly squat. No real heating of the air passing through the core happens until the thermostat opens. It never does get there on my engine with a 90C thermostat. Even if you have a lower temperature thermostat installed the exhausted heat flow from the radiator will be much less because of the law of thermodynamics. Heat only flows from high to low and with a 70C thermostat the efficiency is so low in efficiency passing the heat off into the air that it’s working about equal to the head’s cooling rate only. This just makes the overcooling AND the overheating worse. The engine temp will get stuck at 70-80C and I freeze cause the cockpit heater only makes this worse. Only if I close the heater water flow off will the engine finally climb up to barely 90C. The difference of 15-20C warmer water circulating through the heater has to be experienced to be believed. According to the good old laws of thermodynamics this makes perfect sense. None of this stuff is intuitive unless you’ve got an engineering degree or in my case had the on the job experience.

Chris,
If Lotus kept the same opening size in the front grill for every version of the Elan then 40sq/in of area blocked off will be magic size. Trust me.

M100,
That’s why you guys in the UK should be very concerned. I’m taking a different route to solve this. I’m going to add loop of tubing into the top tank of the radiator and pass all the engine oil through so it gets heated up to the water temperature. Then going to partially insulate the oilpan to reduce the heat loss from the air blowing past it. The reason not to stop all the airflow from the bottom is simple. The alternator will burnup from overheating. To keep the alternator alive where I live I have to add a heat shield between the exhaust manifold and the alternator. Also an air deflector which hangs 1/2" below the chassis to force cool air to the backside of alternator when the car is moving. Since I’ve done these two mods the alternator has not died since.

Wish I had picked up on this trick when I still had the Maserati Biturbo. They would get cooked sitting within inches of the turbo and be toasted and die everytime about every four months. :imp: :angry:

My optics stuff usually gets cooled down to 77Kelvin (liquid nitrogen) or 4K (liquid helium). Ironically, the cooling capacity is very small at those temperatures since the gradient is never very large if you can possibly help it. Better know what you’re doing or you’ll screw the pooch. :open_mouth:

LOUVRES:- this could be the answer to the problem,just like on the front of the Rolls-Royce,a louvre panel attatched to the radiator(so as not to restrict air to the intake filter) operated from inside via the redundant locking choke knob???
John :wink:

P.S. Keith
I am sure Mr Vizard reckoned that 72 was the best operating temperature?
John :wink:

A mate with an old Rolls-Royce has this arrangement but the thermostat operates the louvres via a multiplier linkage.

Keith, along your tube in a radiator idea have you looked at the laminova heat exchangers? I’ve retrofittted one to the Elise and it warms up and stabilises the oil temperature very quickly as well as speeding up coolant temperature rise (car runs all the year round)