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MG Midget and Sprite Technical - Ceramic exhaust coating


Just a general question I was recently reading an article in the MGOC magazine about applying a ceramic coating to your exhaust system but mainly the manifold with the aim of reducing under bonnet temperatures and thus potentially reducing problems relating to fuel evaporation/starvation. One manufacture/supplier suggests in tests that their coating could reduce manifold temperature up to as much as approximately 33%. Has anyone used this type of coating and found it beneficial or had any problems with it?

My car has a stage 3 tuned engine with a Webber carburettor. I have added the larger 5 blade plastic fan and use Forelife as a coolant. On a “normal” UK summers day in traffic I don’t have problems, however once stuck in slow moving traffic or stop at a series of traffic lights then the car can start to be a bit lumpy until the temp gauge goes back to its normal resting place (just below Normal).

Thanks for any advice

R Barker


I recently had a used stainless steel manifold for my K-series conversion coated by Cam Coat.

I can't comment on the performance yet as the car is currently with Frontline for engine fitting but the quality of the finish appeared to be very good.

Like you I was concerned about under bonnet heat build up, I have a grp bonnet, which is why I took this route.

P R Clark

What on earth is a stage 3 engine?!

There are no clear stages for a-series engines other than the age old stage1 kit for the mini's

If you have trouble with unde bonet temps try it
Or fit an electric fan that cured the problem for many people
Onno K

An electric fan does very little for under bonnet temp. Wing vents could be more beneficial.
I have the same; engine temp always ok, even in slow traffic, but when the traffic light takes too long engine stumbles, flutters without power for a few hundred meters orso.

Wing vents still under construction...
Alex G Matla

Bad panel gaps give a similar cooling effect. Works for me :0)
Gary & Gaps

You can buy insulating exhuast wrap, I saw it recently somewhere on the web.

But I also read an article about it causing too much heat to build up in the exhaust system. If I can find it again, i'll post it.
Lawrence Slater

I think it was Peter Burgess on here a while back advising not to use any type of wrap or coating as he had seen increased heat build up in the head when this was done. I think he may have also said they had seen similar with stainless manifolds as well.

T Mason

Here's one.
Lawrence Slater

I've had Camcoat applied on the manifolds of the last two cars I've built. The initial coating was done on a mild steel manifold fabricated for a Fiat T/C that powered a historic replica. The system had long primaries and to avoid under bonnet(which was GRP construction) heat the fabricator suggested mild steel with a ceramic coating. As a point of interest, he advised that stainless would retain its heat for a longer period. The under bonnet temperatures were never a issue during the period I had the car. The particular finish I chose was 'Cermakrome' and once used, had a dull alloy colouring. A few years later I saw this finish mentioned in a midget tuning book (title escapes me for the moment!)
The second manifold is on my Sprite and is a Maniflow product. And again, no under bonnet heating problems. Engine is 1380 with Weber 45 etc fitted.
The added bonus is there are no rusty pipes to to behold when you tip the bonnet open.
Derek Stewart

I used camcoat on my race exhaust and it worked really well - a very noticeable reduction in temperature.
John Collinson

Exhaust wraps should probably be avoided on any car used on the road due to pipe rust/durability. Each time wraps have been discussed over the years, folks who have used them reported rapid corrosion of the pipes, due to the trapped water.

Ceramic coatings, on the other hand, are effective against corrosion and are also some under hood temperature help.

For the maximum benefit, the inside of the pipe should be coated as well.

There was some discussion here about a year ago about some theory that a coated exhaust pipe would cause some kind of temperature trouble in the head, or cause improper exhaust gas velocity, but I've never seen either on the cars that I've fitted ceramic coated pipes to, or heard of trouble on other vehicles (ceramic coating is pretty popular in the hot rod world, for instance).

Norm Kerr

I thing wing vents would help - perhaps Carl will make a batch for us in return for which we'll make him rich?
Daniel Thirteen-Twelve

I've yet to see some wing vents for Spridgets. Does anyone have a picture?

And how about bonnet vents?

Letting the heat straight out the top must be a winner, but I've never seen one other than just a hole cut in the bonnet. Again, anyone any pictures?
Lawrence Slater

I have ceramic coated extractors in my car, they still get hot but a lot less than you would normally expect an exhaust manifold to get. I am able to work around it and brush it without burning myself when hot, though I wouldn't be inclined to hold my hand on it for long.
Andrew F

We have a straight six TVR that we look after. We had the manifolds coated, and it made a huge difference. The heat build up with car here used to be a serious problem.

Richard- All five of my MGs have ceramic-coated exhaust manifolds, so I figure that it's safe to tell you that it's a good idea, if you have it done properly. In my case, I use Jet-Hot coating. Jet-Hot coating is a ceramic coating that can be applied to coat both the interior of the exhaust manifold as well as its exterior. The greater part of the heat will have nowhere to go except out through the exhaust system, thus it will greatly reduce underhood temperatures. This is a significant factor as exhaust manifolds often reach temperatures above 400 degrees Fahrenheit (204.4 degrees Celsius). As a general rule, the reduction in temperature when using the “Sterling” coating can be relied upon to exceed 300 degrees Fahrenheit (148.9 degrees Celsius), while the reduction in temperature when using the “Extreme Sterling” coating can be relied upon to exceed 400 degrees Fahrenheit (204.4 degrees Celsius). Thus, the cooler air being inhaled into the engine being denser, more fuel can be mixed with it to result in a more powerful fuel / air charge. At the same time, it decreases deceleration of the exhaust gases, the sustained gas inertia thus enhancing the pulsed-vacuum scavenging effect of the cylinders. The increased velocity of exhaust gases produced by their higher exit inertia not only clears each cylinder more quickly; the resulting improved vacuum effect inside of the combustion chamber draws in the next fuel / air charge more efficiently. Jet-Hot coating does not contribute to hydrogen embrittlement, a condition associated with chromium plating and other coatings in which microscopic cracking can lead to premature failure. One word of warning to those considering Jet-Hot coating or any other type of ceramic coating: Be sure that the entire surface of the exhaust manifold, both the interior as well as the exterior, and that of the flanges is also coated so that the heat of the exhaust gases will travel onward through the system instead of being absorbed and trapped in the metal of the exhaust manifold, otherwise the absorbed heat will create the same problems as in the case of lagging the exhaust manifold with insulating wrap. Warping of the exhaust manifold would become something to be expected, and overheating and consequent warping of the cylinder head would also become a distinct possibility. Jet-Hot has a website that can be found at .
Stephen Strange


Thanks for your all input – I’ve read many posts about the good and bad points of using the more traditional style of exhaust wrap and that it can cause rust/durability problems, hotter heads and therefore you could be more prone to HGF.

Shawn – I know few people who have TVR’ over here in the UK and heat build up is problem for them as well, I let them know about it.

Stephen – Thank you for the link, the company looks good unfortunately I am based on the other side of the pond! I have found a several companies in the UK that offer a similar service, although the one company I have contacted only recommends coating the outside of the exhaust!

Taking all things into consideration any reduction in heat under the bonnet has got to be good especially if the reports into bio-fuels being susceptibly to heat are true. Well xmas is coming I can only live in hope.

Thanks Richard
R Barker

Speaking of bio fuels, when are we due to experience the delights in the UK?
Lawrence Slater

Lawrence we already do; diesel has been 5% bio since last year, many petrols contain a few % bio-ethanol. Like speed limits and enforcement, it will creep in gradually...
David Smith

see this..
Dan Cusworth

I would venture that the one company that you contacted doesn't have the capacity to coat the interior of the manifold. Bad idea! Coating only the exterior is hardly any better than lagging with insulation, and the exhaust manifold will turn into a heat sink. Find a company that will do it right.
Stephen Strange

This thread was discussed between 23/11/2011 and 24/11/2011

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