Hi Guys
I am a new member and have been drawn here following a google search around the issue of displacing the heat generated within the Jaguar MK2 engine bay.
I came accross a previous post by the user Primaz in which he explained how he managed to solve this issue by intoducing an air ram.
Has anyone else on the forum carried out this MOD?

 

I don't know the full details of Primax lower scoop but that cutaway he has done at the back of his engine compartment to vent hot air ~ sort of triangular shape ~ is a very good idea. A few people have done it. I think Lickahotskillet has.

Getting hot air out to allow flow is always a good idea.

IIRC all his valance scoop air does not go through the radiator it just vents the engine compartment via these triangular vents..

 

The best way to cool the engine bay is to lag the exhaust manifolds with Exhaust wrap tape https://www.oldhallperformance.com/h.../exhaust-wraps or to have the exhaust manifolds ceramically coated. https://www.zircotec.com/exhaust-coa...BoCK9gQAvD_BwE
I don't endorse either of these companies they are just to show a product.
By reducing the heat coming from the exhaust manifold into the engine bay will possibly reduce the temperature by 30 to 40%. When I was racing both my Mini and Lotus Seven had exhaust wrap on the manifolds so I know if works. It kept the heat away from the radiator on the mini and from a water pipe on the Seven significantly reducing the engine bay heat.

 

Is this related to the current very high temperatures in the UK at the moment ? I never had a problem with heat, in fact the heater doesn't throw out enough ! However, in Paul Skilleter's book on Jaguar saloons he mentions that the Mark 2 suffered from a dead air condition at certain speeds that would lead to overheating, but doesn't expand on this at all. Whether Jaguar did anything about it we will never know as all the designers and engineers passed away long ago.

 

I've also heard of the dead air (stagnation of the flow through the radiator) in discussion with the Ron Beattie (Forward Engineering). As I recall, it occurs at about 80 mph. My guess is that it's air flow under the bumper producing pressure in the engine bay. It makes the engine driven fan indispensable. The solution we proposed, but never tested, was a front Valence below the bumper with an opening to a duct that guides air up (roughly through where the access panel is situated) and through the radiator.

It and the holes in the inner wing are nice ideas, but I never had an overheating problem with my car in standard form. That's in spite of working hard on continental motorways and Alpine passes.

 

A decent oil cooler is also a good idea.

 

I've never monitered oil temperatures, is that a concern at normal highway speeds?

The natural gas fired insustrial engines I am used to had an oil temperature aim point of around 75-85°C, I'm assuming gasoline engine oils are similar?

 

I wrote 'standard form.' That's not quite correct as at some point I'd fitted a small overflow catch tank though it wasn't to combat overheating. You often read that the top tank of the radiator serves as a header tank and nothing extra is required. If you fill the radiator to the top, the system displaces some water the first time it heats up (or goes into heat soak after heating and then stopping) and then doesn't lose any more water. My experience was that it was almost, but not quite true. Especially with a lot of high load use, the system would continue to expell a little water every time the car stopped, slowly lowering the level in the radiator. To avoid the coolant going too low on long continental journeys, I had to top the radiator every morning (a nuisance) and suffer people telling me that my car was spewing coolant when I stopped after a long run. So the small ex-BL header/catch tank was a convenient addition.

 

Different strokes for different folks. It's all part of the design philosophy. e.g. VW aim for a bulk oil temp of 127 deg C for the sake of engine efficiency. They are about the highest I've seen in normal cars.

It is why you could run Alfa's flat out all day long. Close to a 10 litre sump & huge aluminium finned exposure to the under car air flow built into the sump.

 

Like Primaz I shoved a V8 into a Mark 2 and was very concerned about heat management. I ceramic coated my manifolds and downpipes and installed a rubber flap across the back of the front suspension crossmember - the purpose was to accelerate airflow and create a low pressure area under the back of the engine compartment to pull hot air out at speed. I discussed this along with Alan's approach with a neighbor who was an engineer at Pratt & Whitney specializing in high speed airflow. He didn't make eye contact as I described my idea - said something about the car resembling a brick moving through the air - and suggested I take the ram air approach. I did construct a simple scoop but ended up installing the flap which seemed a more elegant approach. I have no idea if it works, but the car does fine in hot weather. We're just coming out of an extended heat wave with temps in the 90's - the car has 2 speed electric fans which cycled between low and high speed in stop and go traffic, but rarely high speed when traveling above 30 mph or so. This suggests I have good airflow through the engine compartment at speed. If we can run 400hp and ac without overheating I don't think you should have any problems with a stock setup. Good luck with whatever approach you take.

 

I'm very interested in the Zircotec heat reducing exhaust manifold coating that Cass 3958 posted a link to earlier in this thread. The Zircotec company Cass posted a link to is located in the UK, Does anyone know of a similar business located here in the USA that does this type of heat reducing coating on exhaust manifolds ? As always, your thoughts are really appreciated !
Schmitty

 

Zircotec have a good reputation and the finish looks good. Is there much difference between a courier across the US and across the Atlantic? I've seen the name Jet Hot mentioned as a US company. I've no idea about their quality.

 

I don't understand this engine bay heating up problem which is being bandied about. We are dealing with ancient technology.
The MK1/2/Stypes have been around for 50 to 60 years or thereabouts. Actually MK1s go back 67 years.
Early MK Jaguar engine cooling systems were fickle and limited as their initial design was obviously for cool climates eg GB and the continent.
The early Mk1 s had a 4 blade fan which probably blew less air around than my wife's hair dryer.
Later models with the multi blade fan and increased radiator capacity were much better.
Overall I have found that a clean radiator and cooling system goes a long way to keeping the engine cool and I live in a sub-tropical area with summer temps in the high 30sC and occasionally low 40sC
I have seen electric fans fitted but caution anyone doing this of the need to get rid of the old Lucas generator and fit a decent alternator.