insulation to the footwell

[bob hughes]

Well it is the beginning if spring here and another mad dash in the ongoing saga of the rolling restoration. This time I am replacing the left had floor and sills ( rockers - why are they called that?)

The old girl is a couple of feet off the ground and I have just stripped out the exhaust and what was left of the insulation to the footwell in readiness for some major cutting.

Looking foward, is there any thing I can do to improve the insulation on this side of the car. There appeared to be an air gap between the insulation and the foot well, created by little square packers, I guess that is the norm, but hot air can circulate into this space and heat up the metal?

The was no insulation above the silencer (muffler), I think that I have bought that in the package form AH is there a gap behind that as well?

Any assistance / tweaks to improve the insulation around this area would be appreciated.


Bob

 

[EV2239]

Originally the cars wer sold with a 160 degree thermostats, but customers in North America complained that the heater wasn't very effective, so BMC changed to a 180 degree one instead.

As we don't use these cars much in cold winters and because lower temperature is not a bad idea on old cars, it might be a good idea, if you're not already, to switch to a 160 degree thermostat.

Just a thought.

Ash

 

[Bob_Spidell]

Looking foward, is there any thing I can do to improve the insulation on this side of the car. There appeared to be an air gap between the insulation and the foot well, created by little square packers, I guess that is the norm, but hot air can circulate into this space and heat up the metal?

The was no insulation above the silencer (muffler), I think that I have bought that in the package form AH is there a gap behind that as well?

Any assistance / tweaks to improve the insulation around this area would be appreciated.


Bob

IIRC, there are standoffs under the shield above the muffler. I always assumed this is to provide better insulation; i.e. stagnant, dry air is a good insulator, but as you point out air will circulate. Possibly, the standoffs are there to allow any water that gets caught up there to dry, but why doesn't the insulation on the footwells have standoffs (maybe because not very much water gets into the engine bay)?

Best solution is to put additional insulation under the carpet; e.g. 'Dynamat' or similar. I put cheap, shredded cloth/aluminum foil stuff under the front carpets and the gearbox cover and that helped a lot.

You could also wrap the muffler in header tape, but some claim that causes erosion of the metal.

 

[Bob_Spidell]

Originally the cars wer sold with a 160 degree thermostats, but customers in North America complained that the heater wasn't very effective, so BMC changed to a 180 degree one instead.

As we don't use these cars much in cold winters and because lower temperature is not a bad idea on old cars, it might be a good idea, if you're not already, to switch to a 160 degree thermostat.

Just a thought.

Ash

This gets debated a lot, but the thermostat is there to set a minimum running temperature, not a maximum. Once the thermostat is fully open the temperature is determined by the load and the overall efficiency of the cooling system; e.g. on the highway in Arizona in July your coolant temperature will likely be 190-200degF whether you have a 160 or 180deg thermostat.

The 'ideal' running temperature is probably around 190degF or so. Running too cold is not good for any engine; the oil, for instance, needs to get over 212degF to boil off water and other contaminants. A cold engine has to run richer--hence the choke--and the excess fuel washes oil off the cylinder walls and ends up wasted in the sump. I believe 'modern' cars are designed to run in the 190-200deg range as normal, for efficiency and longevity.

 

[57_BN4]

You can cut down the heat emitted from the exhaust system by ceramic coating it. Reduction in heat ranges from about 25% to 50% depending on cost. Well worth it IMO and looks nice too.

Andy.

 

[Bob_Spidell]

I've wondered about one possible side effect of wrap and coating: since most mufflers are some form of glass or steel wool pack keeping more heat in the system could cause them to blow out more quickly. I noticed after I wrapped my downpipes the exhaust felt a lot hotter, but unfortunately I didn't think to get before/after temp readings.

 

[EV2239]

Originally the cars wer sold with a 160 degree thermostats, but customers in North America complained that the heater wasn't very effective, so BMC changed to a 180 degree one instead.

As we don't use these cars much in cold winters and because lower temperature is not a bad idea on old cars, it might be a good idea, if you're not already, to switch to a 160 degree thermostat.

Just a thought.

Ash

This gets debated a lot, but the thermostat is there to set a minimum running temperature, not a maximum. Once the thermostat is fully open the temperature is determined by the load and the overall efficiency of the cooling system; e.g. on the highway in Arizona in July your coolant temperature will likely be 190-200degF whether you have a 160 or 180deg thermostat.

The 'ideal' running temperature is probably around 190degF or so. Running too cold is not good for any engine; the oil, for instance, needs to get over 212degF to boil off water and other contaminants. A cold engine has to run richer--hence the choke--and the excess fuel washes oil off the cylinder walls and ends up wasted in the sump. I believe 'modern' cars are designed to run in the 190-200deg range as normal, for efficiency and longevity.

Bob
There are a lot of generalisations in your post that ignore the practicalities of managing older cars with less effective cooling systems.

Most were designed to run at 160 degrees, my '51 Bentley is and water loss through evaporation becomes a problem in hot climates. Slightly later cars like Healeys were designed for 160 too and if their oil approaches 212, the pressure drops alarmingly, so whilst I agree with you in principle, I think it's mistaken to dismiss the lower temperature thermostat so lightly. I think it might be beneficial.

My son runs a business restoring and maintaining mostly Older Rolls and Bentley, but some of the more run of the mill stuff as well and many of his customers drive across Europe in them in the hottest weather, so we do understand the heat issues in Healeys. Between us we have nearly sixty years of experience with these things!

www.richardjamesupholstery.com if you're interested in his work.

Ash

 

[tahoe healey]

Bob is correct. The thermostat opens when temps are high enough to need the radiator for cooling, otherwise the radiator is by-passed. Once opened it will close only when cool enough to keep the engine from getting too cool. The thermostat is only a gate for the radiator when starting the car. It will do nothing for an over heated car. The 160 and 180 degree thermostat makes no difference once opened.

 

[EV2239]

Well on my Bentley the engine temperature is affected by the thermostat. I have a 74 (160) in it and in winter it runs slightly below and in hot summer, perhaps 78 (175). Only in traffic jams and on steep hills does it rise to return to normal once we reach the level.

My Triumph also has a 74, but, as they do, runs at 85 or just below.

If I fit and 82 (185) to the Bentley as suggest by the company for winter use, in hot weather it gets too near boiling on hills and in traffic jams and loses water. Not such a problem with a 4 psi, pressuriised system, but it can be an issue. More important is that that it will reduce running temp overall and this can be quite a benefit with the Healey, not just because of falling oil pressure, but also because in hot weather fuel vaporisation can be a real pain.

Anyway I apologise for veering away from insulation.

Ash

 

[Bob_Spidell]

Originally the cars wer sold with a 160 degree thermostats, but customers in North America complained that the heater wasn't very effective, so BMC changed to a 180 degree one instead.

As we don't use these cars much in cold winters and because lower temperature is not a bad idea on old cars, it might be a good idea, if you're not already, to switch to a 160 degree thermostat.

Just a thought.

Ash

This gets debated a lot, but the thermostat is there to set a minimum running temperature, not a maximum. Once the thermostat is fully open the temperature is determined by the load and the overall efficiency of the cooling system; e.g. on the highway in Arizona in July your coolant temperature will likely be 190-200degF whether you have a 160 or 180deg thermostat.

The 'ideal' running temperature is probably around 190degF or so. Running too cold is not good for any engine; the oil, for instance, needs to get over 212degF to boil off water and other contaminants. A cold engine has to run richer--hence the choke--and the excess fuel washes oil off the cylinder walls and ends up wasted in the sump. I believe 'modern' cars are designed to run in the 190-200deg range as normal, for efficiency and longevity.

Bob
There are a lot of generalisations in your post that ignore the practicalities of managing older cars with less effective cooling systems.

Most were designed to run at 160 degrees, my '51 Bentley is and water loss through evaporation becomes a problem in hot climates. Slightly later cars like Healeys were designed for 160 too and if their oil approaches 212, the pressure drops alarmingly, so whilst I agree with you in principle, I think it's mistaken to dismiss the lower temperature thermostat so lightly. I think it might be beneficial.

My son runs a business restoring and maintaining mostly Older Rolls and Bentley, but some of the more run of the mill stuff as well and many of his customers drive across Europe in them in the hottest weather, so we do understand the heat issues in Healeys. Between us we have nearly sixty years of experience with these things!

www.richardjamesupholstery.com if you're interested in his work.

Ash

I stand by my statement that the thermostat sets the minimum coolant temperature--assuming the engine gets hot enough, sometimes mine doesn't--not the maximum. Once the valve is fully open the maximum temperature is determined by the efficiency of the cooling system and the load (the term 'dynamic equilibrium' comes to mind). If your Bentley can maintain a lower temp with the thermostat open that means you've got more than adequate cooling system for a given load (the big radiator up-front and loose cowling probably helps a lot).

Here's a good writeup with a graph showing temperature vs. wear:

https://www.carnut.com/ramblin/_cool3.html

Big Healeys run fine with 180deg thermostats, assuming the entire cooling system is in good nick. Mine's been through Death Valley at 115degF (in the shade) pulling a long grade and passing lesser vehicles stuck on the side of the road. If you tune for 160degF running you're running richer than you need to; my BJ8 sees 24mpg at nominal 'highway speed.'

Agree on the oil pressure dropoff, but that's also a clearances and oil pump capacity issue. High oil pressure might give bragging rights, but all the engine needs is enough oil to keep everything turning. Mine drops to near-zero on hot days in traffic, but the engine has almost 100K miles and is still running strong. Note also that too-cool engine temps are generally blamed for sludging.

If it was my Bentley I'd want to find out why I'm losing coolant and fix it. My Healey never loses a drop.

 

[EV2239]

Bob

The 46-55 Bentleys and Rolls-Royces aren't pressurised, hence evaporation.

Running a Healey on the lower temperature thermostat the earlier models were sold with will alter nothing, certainly not mixture, but it might be helpful in the summer. Have a look at the workshop manual where you'll see what I'm saying.

Ash

 

[Bob_Spidell]

Bob

Running a Healey on the lower temperature thermostat the earlier models were sold with will alter nothing, certainly not mixture, but it might be helpful in the summer.
Ash

Never said changing thermostats changed mixture. If the engine is running colder you need to dump more fuel into the carburettors to compensate for lesser vaporization and 'wall wetting' of the manifolds and, to a lesser extent, a denser fuel charge; so you'll have to re-tune for that. I did say that's why you need 'choke'--for SU carbs that means a richer mixture and larger throttle opening--when the engine is cold. My BJ8 runs a little rough at 160degF, but smooths out when it reaches the running temperature I've tuned it for (180).

Some people think cooler-running thermostats help because they open sooner than hotter-running ones. I don't think it makes much difference, but if it works for you then good deal.

I believe cooling systems were pressurized, in part, so that engines could run hotter and more efficiently with sufficient overtemp margin. If your engine isn't pressurized you don't have as much margin, so a cooler thermostat would be required but, as I said, your Bentley probably stays below the max capacity of the cooling system. You'll get the wear issues described, but I doubt you drive the car enough for it to matter.

 

[Lotuswins]

Bob: Well it is the beginning if spring here and another mad dash in the ongoing saga of the rolling restoration. This time I am replacing the left had floor and sills ( rockers - why are they called that?)

gdr: Weren't they called, originally, rocker panels, or rock panels? rocks off the wheels would hit them first? (just a thought, don't know for sure).

Bob: The old girl is a couple of feet off the ground and I have just stripped out the exhaust and what was left of the insulation to the footwell in readiness for some major cutting.

Looking foward, is there any thing I can do to improve the insulation on this side of the car. There appeared to be an air gap between the insulation and the foot well, created by little square packers, I guess that is the norm, but hot air can circulate into this space and heat up the metal?

gdr: There are three ways to transfer heat energy: Conduction - when things are touching and the heat flows from one to the other. Convection - when a fluid is between the two items, and the heat is transferred through the moving fluid. and Radiation - heat is radiated to the other item by giving off the energy in a form of radiation.

They put the standoffs in so it prevents conduction and as it is open around the perimeter of the insulation material, the fluid (air) can be displaced, limiting convection, which then limits it to mostly radiation. The muffler, through radiation, heats the insulation, which in turn, radiates heat to the floor board. This is a common method to limit heat transfer.

Bob: The was no insulation above the silencer (muffler), I think that I have bought that in the package form AH is there a gap behind that as well?

gdr: there is a gap between the muffler and the insulation, and the insulation and the floorboards.

Bob: Any assistance / tweaks to improve the insulation around this area would be appreciated.

I hear the dynamat is good stuff, and hush mat too, for the interior. I've seen a vender offer an aluminum/insulation panel that goes above the insulator to add an additional layer of insulation, which is also much larger and ramps down at the edges to limit the radiation to the frame and sill areas. That sounds appropriate too. Jet hot coating of the entire muffler and pipe system would help also.

Jerry Rude
BJ8 1 week to paint!
73 Lotus Europa TCS 'Guenhwyvar'

 

[AUSMHLY]

Looking foward, is there any thing I can do to improve the insulation on this side of the car. There appeared to be an air gap between the insulation and the foot well, created by little square packers, I guess that is the norm, but hot air can circulate into this space and heat up the metal?

The was no insulation above the silencer (muffler), I think that I have bought that in the package form AH is there a gap behind that as well?

Any assistance / tweaks to improve the insulation around this area would be appreciated.


Bob

Hi Bob,

That insulation board, was asbestos. They added the square spacers intentionally to have air circulate between that board and the metal floor. You don't want to fill that gap.

What I did to help reduce the heat was to apply an Adhesive Backed Aluminized Heat Barrier Cloth to the outside bottom of the floor pan. The material has the thickness of fiberglass cloth.

Now I have the factory heat sheild, the air gap and the reflective heat sheild.

Here's a link to the product.

It's sold by Pegaus. It has an adhesive back, so you just cut it to size and press it on. Here's a photo of it.
Cheers,
Roger

 

[Bob_Spidell]

On that note, you could use something like Lizardskin:

https://www.lizardskin.com/

Never tried it myself.

 

[bob hughes]

Wow, did not mean to open a can of worms on the thermostat, all good stuff though.

Thanks chaps for the advice, I had better get down to sourcing that self adhesive ali insulation on this side of the pond Roger, and also opening up the pack to see what I have.

Cheers

Bob

 

[richberman]

I did something akin to Roger, but used Koolmat.
https://picasaweb.google.com/11008734965...779043033794722

Used it both above the floor and below the floor, then air gap and asbestos-like shield. Also ran it on both sides of the footwell.

Thanks,
rich

 

[Healey 100]

Insulation is a great idea but don't forget to plug all the leaks you can find on the floor and firewall. Put a shop light in the lower part of the engine compartment at night. Turn out the lights in your garage -- you'll be amazed how many spots of light you'll see through the firewall and floor. All of these need to be plugged, preferably with aluminum tape.

When you are on these road, each of these holes produces a jet of very hot air. Ditto for the transmission tunnel.

I really don't think the thermostat matters much in terms of cockpit heat. The left hand foot well heats up due to heat from the exhaust manifold/pipes/muffler, and these are far hotter than the water temp. I have a 160 degree 'stat in mine, but on hot days she usually runs around 190 or more anyway.

Another suggestions: don't drive a Healey with flip-flops on a hot day!

Bill.

 

[bob hughes]

Flip Flops

I'm with you on that one Bill, only did it once in my 100/6 and thta was a RH drive in a British summer!



Bob

 

[vette]

Hi Bob,

I've been redoing the body on my BJ7 for about 2 years now. I decided to spray Lizard Skin sound and Heat insulation to the inside cockpit area of the car. I will also install new replacement insulation panels to the original locations which are available from many of the supply sources. I sprayed the Lizard Skin about 6 months ago and am very happy with it. It goes on as two products. One for sound deadening the othe for heat insulation. It is water based, very easy to control and clean equipment afterwards. I ordered the recommended spray nozzle which has well defined spray pattern. sprayed the inner firewall, toe boxes, foor. and rear shelf area up to the rear shroud water channel. I'm very happy with it.
Dave C.
PS. I forgot to say that I chose not to use the insulating mats even though I believe they have excellant heat barrier qualities, but I believe they will eventually become water and moisture traps. The lizard skin is bonded to the metal like paint. Water will not penitrate it and there will be no temp differential to cause condensation.