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Old 12-29-2012, 01:27 AM   #31 (permalink)
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the old boat - '93 Cadillac Deville *removed/modified
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Quote:
Originally Posted by euromodder View Post
Keep in mind that most folks on here already have their grilles blocked, which means less air going in. And less heat being blown out.

Sure, there are still a great many leaks - and you actually need them to get rid of the heat from the engine.

Simply blocking part of those leaks already seems to help warm up times ...
The grill block is a vastly different mod, and a good target for temp management at speed. It doesn't do nearly as much at stand still though for retaining heat, but would be more effective than a negligible insulator to the hood.

The grill block, which is more for aereo, works on more of a curve. The engine is designed to shed heat to run in an optimal range. The block just helps you reach and maintain that range more so in the fuel efficiency realm - it doesn't increase temps by any significant margin, unless you overdue and then overheat. You have to seriously modify the coolant system because the car will try to shed any significant amount of excess heat built up by the block.


A possible solution, if you had an engine that could handle the heat soak, would be a rig that could significantly reduce the cooling system so you could build up a lot of heat right before you shut off the vehicle, with an overheat override. There would need to be a lot of testing though as the engine is designed to shed lots of heat; it may only be practical for short term stops. It is basically a prius like system, but soaking the whole engine rather than a small amount of coolant. I'm guessing engineers have tried it before with lackluster results.
Another aspect would be like my old big car has, where the engine and trans oil are routed through the radiator to cool them, but in lower temps the engine coolant heat also warms both. Most fuel efficient vehicles don't have such systems nowadays as the EPA doesn't do fuel ratings in 20 degree temps.


Still, grill block or not, any measure of hood insulation would still have a negligible effect.

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Old 12-29-2012, 01:33 AM   #32 (permalink)
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Quote:
Originally Posted by chrisgerman1983 View Post
R value is pretty irrelevant, glass has no R value but even single pane windows keep the cold out and the heat in.
Error in the logic there.

R value is very relevant in this specific discussion. Hood insulation can only be measured as such. The hood is already enclosed unlike a window before the glass is added.

It is also relevant as all the other avenues to shed heat show dramatic losses that the minimal R value hood insulation can provide can't compete with.


Your example is not comparative.
A better one would be if adding a piece of cardboard to a window made the house measurably more insulated.
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Old 12-29-2012, 02:18 AM   #33 (permalink)
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chrisgerman1983 - '96 chevrolet astro
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You are correct that that would be a better analogy. And yes it would also work very well... people put plastic over their windows all the time, wich turns the air space into an insulator. Most people would be extatic if their home could retain an additional 10 degrees for a 4 hour period.
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Old 12-29-2012, 04:41 AM   #34 (permalink)
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Quote:
Originally Posted by chrisgerman1983 View Post
You are correct that that would be a better analogy. And yes it would also work very well... people put plastic over their windows all the time, wich turns the air space into an insulator. Most people would be extatic if their home could retain an additional 10 degrees for a 4 hour period.
Another error.

An assumption that 10 degrees more than standard is being maintained for any length of time is just that.
A single anecdotal report of "hood felt warmer" doesn't qualify.
I would also argue against the validity of any type of insulation on a typical hood creating a 10 degree difference in any measurable engine parameter.

You can stuff the entire engine bay full of cardboard or bubble foil and you'll only get 10 degrees difference when it eventually ignites.


To your analogy....
The plastic is to reduce drafting from leaky window glazing, frames, and installation framing. The air space created between the plastic and window, if any has little R value, anywhere from R 0 to R 3, and due to its purpose of blocking drafts, the R value as far as the homes enclosure is basically nil as it is outside that enclosure.
Must be careful in comparisons.
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Old 12-29-2012, 11:52 AM   #35 (permalink)
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chrisgerman1983 - '96 chevrolet astro
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There are a few of us that have data that proves the effectiveness. You are trying to debunk data with theory. I have a theory that I believe we should argue... The world is flat otherwise all the water would flow to the bottom of the earth

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