Having had a problem in the summer with getting a little to hot on my sprint, I read that later sprints have a couple of air ducts either side of the engine bay, my car has these but are not open to get hot air away from engine bay via the inner wheel arch.
My question is Should these be opened up and as I don’t drive the car in the wet there should not be a problem with dirt or water being thrown up by the wheels into the duct and eventually into the engine bay.
Regards
G
If I recall the twin cooling holes were introduced as a service bulletin retro fit by Lotus during Series 4 production and were factory spec from about late 1970 onward so it’s odd you don’t already have them.
The twin holes were drilled into the exhaust side inner wheel arch, close to the top. They were then fitted with a wire gauze covering and the Sprint style windscreen washer motor was screwed into the gauze.
I would suggest you drill those holes if you want to clear some engine heat from the bay.
Tim
They are not ducts. They are just the relative shapes of the top mould laying above the bottom mould of the bodywork shell. Why they were made that shape, is probably lost in midst of time.
The 2x circular holes described elsewhere are the keys to venting hot air.
And IMO to still not effective enough. Bonnet vents, especially above the carbs to prevent fuel evaporation, would be much more effective.
Regards
Richard
The problem with vents on the bonnet is the likelihood that the hot smelly air going out of the vent gets drawn into the air intake for the heater. I believe the purpose of the foam strip at the back of the bonnet is to avoid this problem.
The wheel arch is a low pressure area, and a good place to vent hot air. The old style mini’s rad exhausted all of its hot air into the front left hand wheel arch.
Perhaps holes on the front inner right hand wing matching those on the left could be a better answer - unless wetting the ignition system was a concern.
Edit:
Interesting picture below, showing pressure distribution across a car in motion. Presumably, at least part of the pressure at point ‘a’ will be present in the engine bay, although there will be a pressure drop across the radiator. Reinforces the wisdom of having your carb air intake in the front plenum.
My holes, in a similar position to Greg’s (& the washer bag.) Maybe the holes have a larger diameter?
That’s great info guys.I will get this done.
Thanks all
G
Some years ago I posted a clipping from a Hagerty article about overheating. Needless to say I can’t find it either here in the forum or on the Hagerty website.
But, if I remember accurately, it said something like: as a starting point for diagnosis….
This struck me as a solid assertion.
Many years ago I cut the two vent holes in the wing of the S4 that I had at the time to help stop overheating. They made no detectable difference.
Nick
Well as far as im concerned it cannot make things worse ,
and as it was prescribed by lotus on later sprints ,I will do it and see what happens.The car is ok at these temps now, it happened when we had that very hot period a few months ago.
cheers
G
That’s very true - they can’t make things worse! 
G
My car spent its life in hotter climates and to get around the issue of heat the PO fitted a larger fan than the Lotus variety. But more importantly he had a frame made to encircle the fan blades, mounted off the sides of the radiator. This ensures that the fan when in operation drives all the air through the radiator rather than around the front of the grille area. This has proved more than adequate although when I rewired the car I put in place an overide switch. So now the fan can be switched on by the otter switch or manually if I wish to keep the fan running rather than being switched in and out by the otter.
The cage around the fan is made of strip steel and four brackets, so is not too difficult to make and does not look too out of place, once painted, but keeps the car cool.
Tony
I did the modification of drilling two holes and some gauze for extra cooling in inner wing and took her out. The temp was around 85c and I did give her some stick.So at moment there’s no problem with getting too hot.The proof of the pudding will be next summer when temps outside rise.
if anything as I said previous it carnt make things worse.I will post again on the outcome.
Thanks for all the posts on what and how to do it
Cheers
G
The holes in that screen seem a bit small. You can find screen that is rated by the % of open area, and you want something that is 60% or preferably better. 1/4” opening screens (~75% open area) would be adequate to keep the boulders out, while letting air easily pass.
Mucca, or should that be Maga, when we chatted at Castle Combe earlier this year, you mentioned that your car was brick slow. Now that you have shown a picture of the engine bay, it is clear why. Your car will accelerate twice as fast if you have the correct washer bag fitted. Get in touch if you want to be a true ‘boy racer’. Make sure you are sitting down when I tell you the price. And you may want to change out of that white jump suit. We wouldn’t want any stains showing through.
Leslie
Of course it comes with the correct Tudor top, need you ask.
512
its Macca by the way and the old bag has been with me for 45 years.It would be very costly to get rid of her now so I will stick with her for the time being.Thanks for the offer though.
BTW jump suite a little tight now middle age spread .You know what I mean.
Cheers
