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I see Dynamat in the trunk and interior floors, Dynaliner over the Dynamat on the floors and inside the door panels. But, I don't see it used under the hood..?
I'm not saying it can't be used there, just that it wasn't part of the example. I'm not looking forward to pulling my hood, but Vee makes it sound fairly easy, and summer is the best time to do it up here (I don't have a heated garage, otherwise winter would be an even better time to do this project.
I did mine 8 years ago with my hood still on, generic one inch thick material, spray adhesive, used razor to cut out the couple high spots. Still sticking fine 8 years later, hood never came off, looks great.
I see Dynamat in the trunk and interior floors, Dynaliner over the Dynamat on the floors and inside the door panels. But, I don't see it used under the hood..?
I'm not saying it can't be used there, just that it wasn't part of the example. I'm not looking forward to pulling my hood, but Vee makes it sound fairly easy, and summer is the best time to do it up here (I don't have a heated garage, otherwise winter would be an even better time to do this project.
I always believed the V12 was a QUIET engine, mine all are, so noise was never an issue. E fan noise is barely audible.
The foam was a heat insulator, same density as the equally dumb stuff on top of the transmission up in that hump area.
In fairness probably the best, cheapest, easiest, to obtain back in the day, and has lasted 15+ years, waaaaay past the original intended life of the car, IF we are honest.
Technology has caught up, luv technology, and we have better, more efficient stuff available, in many areas.
I also agree that our S2 cars, both 6 and 12 cylinder, never had such stuff, BUT, there was a spray on rough finish insulation material of some sort, and I never took any real notice of it, other than it was there.
Cars in what we call cooler climtes, UK, Canada, etc would maybe be fine with nothing in there, but that is my opinion only, nothing scientific involved, and we certainly dont have a cool climate, so insulation is a given.
wouldn't the air circulate better under the hood without the liner keeping the engine heat trapped under hood?
wouldn't the air circulate better under the hood without the liner keeping the engine heat trapped under hood?
This is, as far as my experiments and measurements have shown, 100% true. I will in due course post some details, but in outline, I recently did some experiments with holes in a spare old bonnet (hood) to simulate louvres. The first time I fitted the bonnet with the holes, I found the underbonnet temps that I was accurately measuring were WAY lower. Bingo, I thought.
Just to be sure I covered up the holes with cardboard and did a comparative test. Only a VERY small difference in the temps, at most 3C. Disappointed does not even begin to describe my amazement at this result.
So I got to thinking what was the only difference between the normal bonnet and the old one, when the holes I had cut were blocked off. And it was the OEM insulation, which is about an inch thick, and hangs down here and there from its fixings.
So I replaced the normal bonnet and removed the OEM liner. Underbonnet temps come down by 7 or 8 degrees, a LOT more wind noise without the liner though. So why the temp drop? I believe two causes:
The upward facing rear lip of the cross radtop panel shuts against the OEM liner, without the liner, speed-rammed air can flow above the panel into the engine bay far easier
The liner itself blocks off air circulation as it semi-rests on bits of the engine here and there (eg injectors, aircon pipes, etc.
So I removed the radtop panel and reduced the height of the vertical lip by about 6mm, and in place of the OEM liner fitted some modern butyl rubber-based insulation called Silent Coat. Thirty self adhesive panels from Amazon at about 30 UKP, so not at all dear. A breeze to fit and only 2mm or so thick. Results:
Car quieter than with the OEM insulator
Under bonnet temps stayed lower than before.
From all this I conclude that promoting more air flowing into the engine bay from around and above the radiator is the best way by far on our cars to reduce under bonnet air temps, and exchanging the OEM liner for a thin modern version is an easy way to do it.
Greg
Last edited by Greg in France; 09-19-2016 at 01:37 AM.
Any air entering the engine bay also needs to leave. If an easy unobstructed path of entry is allowed for extra air to enter there is a good chance air passing through an obstruction such as radiator will be reduced and engine overheating as a result. This is probably the reason the original design called for forcing the air to pass through the radiator by sealing off all those other entry points now being opened up.
My car has no bonnet liner and no signs of one ever mounted. Car was completely rebuild in 1989, so maybe there was one before that
Anyway: My paint is fine, and I do not find noise level high at all. Actually a bit more engine noise would probably make the fuel pump noise less annoying...
This is, as far as my experiments and measurements have shown, 100% true. I will in due course post some details, but in outline, I recently did some experiments with holes in a spare old bonnet (hood) to simulate louvres. The first time I fitted the bonnet with the holes, I found the underbonnet temps that I was accurately measuring were WAY lower. Bingo, I thought.
Just to be sure I covered up the holes with cardboard and did a comparative test. Only a VERY small difference in the temps, at most 3C. Disappointed does not even begin to describe my amazement at this result.
So I got to thinking what was the only difference between the normal bonnet and the old one, when the holes I had cut were blocked off. And it was the OEM insulation, which is about an inch thick, and hangs down here and there from its fixings.
So I replaced the normal bonnet and removed the OEM liner. Underbonnet temps come down by 7 or 8 degrees, a LOT more wind noise without the liner though. So why the temp drop? I believe two causes:
The upward facing rear lip of the cross radtop panel shuts against the OEM liner, without the liner, speed-rammed air can flow above the panel into the engine bay far easier
The liner itself blocks off air circulation as it semi-rests on bits of the engine here and there (eg injectors, aircon pipes, etc.
So I removed the radtop panel and reduced the height of the vertical lip by about 6mm, and in place of the OEM liner fitted some modern butyl rubber-based insulation called Silent Coat. Thirty self adhesive panels from Amazon at about 30 UKP, so not at all dear. A breeze to fit and only 2mm or so thick. Results:
Car quieter than with the OEM insulator
Under bonnet temps stayed lower than before.
From all this I conclude that promoting more air flowing into the engine bay from around and above the radiator is the best way by far on our cars to reduce under bonnet air temps, and exchanging the OEM liner for a thin modern version is an easy way to do it.
Greg
Got some of this Silent Coat and replacing my hoodliner. Does the sticky side hold in the heat or did you use 3M #80 spray gule as well?
It held on like a drowning man to a life raft! Be very carefull to place it exactly first time as it grips straight away.
Yes I gave it a good go. Measure 5 times to Fu*k it up once... So made paper template from measurments. Offered template up and had to make large adjustments by folding the paper card and taping it to the hood. Spent most time getting this right. Just did one side as then mirror the pattern. Cut out the sheets and found I could make it fit with 10 sheets. Worked very well, I use a paint brush and roller to flattern it back and then I hot the Silent Coat roller today and finished off the edges.
Yes it is the stickyest stuff in the world as an off cut stick to my shoe sole....
Test drive today and workwd really well, much lower temps pn top of the hood 45 not 65 °C. Engine stayed very cool and the silent coat stay on very well. Higjly recomend this stuff of you are doing the liner and can be done while on the car if planing is very thourogh and you know what piece goes where first time.
Don't forget the source of noise - vibration - the bonnet is a large vibrating surface and it will transfer that vibration through the structure and the air. Mats like these act like dampers, I use Dodo mat which is very similar both in appearence and application, I have another version called Dodo Thermo liner installed on the roof above the headlining and dodoi mat inside the doors - it will get under the bonnet / hood sooner or later.
Interesting that the retaining plates for the insulation are there - mine are on a shelf where they will likely remain since there's nothing for them to hold up.
Pray you never need to remove it though - getting a drowning man off a life raft will seem like childs play .... and cleaning up after it is another exercise.
The round plate above the capstan is a safety item, Ben, which however unlikely the stuff is to come loose, I too have kept.
The metal strap across the more forward part can go, as mine has; but the rivets do have to be drilled out.
Hmmm ... the round plate was actually holding the original insulation on mine - that has a hole in it - metal strap and such have all been removed - had to in order to clean up and remove the surface rust that had taken root under the insulation which is another good reason to get rid of the absorbent monstrosity.
Don’t over think it. I just did this myself and it’s a 30 minute job. Bought a roll on Amazon for less than $50 and a roller tool. Measure it, mark it and cut it. No need to remove the hood. Peel and stick simple. Holds up fine and resists heat and crumbling etc.
I havent had one on my car for about 4 years and Im considering putting one on now since I just want it to look better under the hood. Ive consider several options, but Im leaning towards a generic black matte padding or go with the gold heat shielding stuff from amazon. My paint hasnt gone to hell, but it would be nice to not expose it to more heat.
I don't think the engine heat is even close to the punishment the sun can dish out, the underhood stuff is only about noise from a design perspective as far as I know. The 'gold' heat shields are reportedly the best but there's a difference between gold colour and the material being gold by its nature aka Zircoflex - insanely expensive but also extremely effective - same stuff as used on satellites etc ...
I think with paint it is as important to keep as much dirt etc as possible off it (which judging by that image you do) - especially that micro dust that comes off other peoples brake pads etc - then a decent wax and sealer is about the best you can do, the other materials used here don't look too bad - as I mentioned I use Dodo matt.