Hey everyone. First off, sorry if these questions have been done to death, I've yet to Master finding existing threads...

While sorting other various issues with my '62 Mk2, I'm also looking into ways to lower the temp under the bonnet.

Since coating the exhaust headers appears to be rather hit or miss, I'm considering wrapped pipes instead...would this be more effective to lower the temp in the engine bay?

...and for the same purpose, how much of an improvement can be expected by installing an aftermarket oil cooler?

For the record, the car has a new water pump and alloy radiator, with the correct fan and intact shroud, and the gauge reads just a tick above 70c (confirmed with a laser gauge pointed at the sender) on +/- 80f days...I'd just like to do as much as possible to avoid issues during hot days and/or heavy traffic.

​​​...and the car is in southern California, not Costa Rica.
TIA!

 

This is what Cass did to his Lotus & it made a big difference. We use rope heat wrapping in SA.

 

Engine Bay temperatures to me are a separate issue. A good coating is https://www.jet-hot.com/thermal-barrier/ or for wraps if you prefer www.heatshield , Either will help the temperature a little but regardless if you create too much of a barrier the heat will get trapped and then the metal will get brittle and fatigue. I had a set of headers fatigue with the metal becoming brittle due to the wraps trapping the heat. I think the coating is better but in realty more of a waste like all of the other insulations, etc. If your radiator system is working then stop wasting brain cells on trying to insulate as you are missing the problem of the Jaguar engine bay being an oven which needs better airflow not more band aides on exhaust, etc.

The Jaguar's issue is not the header heat or radiator heat, but rather you will always get heat as that is the nature of a combustion engine the issue is there is no good way to get airflow in and to exit out. That is why it creates almost an oven of air that is trapped. The more you waste time assuming it is some part of the engine system and you try to insulate it, etc. that does not really address the bigger issue of airflow. As I posted I cut out those triangular wings in the lower inner fender well and that coupled with the air scoop enables fresh air to be pulled under the bumper and front of the car then get directed around the engine and flow out thru those two ports. That works the best or you can louver your hood but to me I like the stock hood look better. Believe me I tried every conceivable option since I am pushing 500 HP via a V8. Most other cars have a better design of venting the engine bay itself. You need to get air to flow in and out period. I wrapped everything, used the best header coatings, fans, etc. but the issue is those are band aides and you will still end up accumulating heat that does not exit the engine bay. The Jaguar is so bad I had coil packs melt while the radiator kept the engine cool until I did those openings on the inner fender well coupled with the ram air scoop.

 

If manifolds on a dyno don't mind glowing orange embrittlement is of little concern with cast iron. I'm talking about weeks of running 24/7 in our labs.

 

Several things I disagree with Primaz and this is not to cause or start an argument, purely an answer which is different to yours.

First of all a Mk2 / S Type Jaguar built in the 1960s did not have any form of over heating problem when new. Period. If it had then I am sure that they would all have been recalled and redesigned to solve the problem. Now a Mk2 / S Type jaguar in 2023 which has not had an engine rebuild, still running the original radiator and is suffering wear causing more internal friction is going to produce more heat. Yes the heat gets stuck under the bonnet and better air flow will get rid of the heat from under the bonnet but your band aid analogy of wrapping the exhaust manifolds is exactly what you are doing by creating more air flow. I must point out we are talking about a standard 60 year old 3.8 / 3.4 Jaguar engine that produces 200 bhp on a good day and is driven by Miss Daisy herself not her lunatic nephew with a Crack habit who has secretly installed a rocket motor from the Apollo space program.
If you want to reduce the temperature of the engine (not the air temperature under the bonnet) then a really good service, cleaning all the oilways you can get to, flushing the coolant system, fitting a new water pump and having a having a good service regime will do more to cool the engine than improving air flow.
Now if we have an engine that runs at normal temperature because it is well maintained but the temperature under the bonnet is in the opinion of the owner hotter than it should be then removing hot things from under the bonnet is the best way to bring it down. Yes at this point better air flow so the hot air is removed would be great but I am not really into hacking lumps out of the side of my engine bay to do this. Fitting an after market air scoop on the front of a stock car to me is like you cutting louvers in the bonnet. Not cool. So in my opinion removing things that are hot like the heat from the exhaust manifold is key. Heat wrap on the exhaust manifolds of racing cars has been used for as long as the Mk2 / S Type Jaguar has been around. It works believe me and it is only recently that ceramic coating has taken over because it is a modern process and works. If you are looking at keeping the car looking fairly stock under the bonnet then ceramic coating is the way to go.
Have a read of this bumf from a company called Funk Motor sport. They quote a reduction from 592 degrees on an un treated exhaust manifold coming down to 475 on a standard ceramic coating. A drop of 112 degrees. They then do a Titanium Lava rock exhaust wrap which reduces the temperature down to just 180 degrees a drop of 412 degrees from the untreated manifold. This is what I used on my Lotus seven and can be seen in the photo above that Glyn posted. Where does the heat go? straight out of the end of the exhaust pipe and does not pool under the bonnet.
https://funkmotorsport.com/is-cerami...AaApz_EALw_wcB
So if you are looking to reduce heat under the bonnet, clean all the oilways in your engine, clean the waterways in your engine, replace the water pump for a new one to get better circulation, Yes increase air flow around the engine bay, reduce the heat in the engine bay with ceramic wraps and lastly don't stuff a 500 BHP V8 under the bonnet where its not designed to go.

 

Hey Cass, thanks for that.

The car ('62 Mk2) has a recently rebuilt engine, with an alloy radiator and runs 100 percent coolant formulated for an older car... don't recall the maker, I just call it the purple stuff 😎, and runs right around an indicated 70c, which has been verified by a laser gauge reading taken at the sender plug.

That being said, I'm aware of the fact that coated headers allow much of the heat to be carried away via the exhaust system, rather than it soaking the entire engine/gearbox, yet I've talked to many who say the coating usually doesn't last, which is why I asked about wrapped header pipes....for me, it ain't about performance, just getting as much heat out the tailpipe as possible....even if it's say 40 degrees cooler, that's enough to make the difference between hot, and too hot, right?

If you, or anyone else can recommend anybody doing this level of coating here in California (or at least somewhere in the US), I'm very interested in reaching out to them.

Thanks again for your input, much appreciated mate!

 

Personally for me if the engine temperature is fine and the car runs and drives well then I wouldn't worry about underbonnet temperature as its largely irrelevant. Yes the few plastic parts like the washer bottle might suffer over time but its how the cars were designed originally and they ran like this for many years.

If you have do start to have problems with engine temperature in future then do as Cass has said and fully service the engine and cooling system.

Things like addiitonal electric cooling fans and cutting extra vents are simply sticking plasters that cover a deeper problem on a standard car, if on the other hand the car has been modified as with Primaz's then these are likely to be necessary due to the air flow issues described.

 

I have used and am happy with https://www.jet-hot.com/thermal-barrier/
They are in the US, just send your parts and they will turn them around fairly quickly.