Coating the underside of the intake manifold to reduce heatsoak?
03-21-2007, 05:24 AM
#32
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Join Date: Feb 2000
Location: Lexington Park, Maryland, USA
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When doing this test just keep in mind that the epoxy can be the same temperature as the uncoated metal yet it will not transfer heat as well. In otherwords, like the space shuttle tiles, they can be HOT yet not hot to the touch. Same with the epoxy and it's transfer of heat to the engine intake air.
Karl
Karl
03-21-2007, 05:42 AM
#33
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Join Date: Feb 2000
Location: Lexington Park, Maryland, USA
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more to the caution when interpreting future tests...... another quote from Randy Stone....
And more from Randy Stone concerning his WAG on the actual horsepower lost from intake air charge heating. I think it'a a very good wild *** guess and somewhat conservative.
(possibly the forumlas will not paste into the quote)
quote:
One thing Brad is forgetting is that different substances, while at the same temp, transfer heat at different rates. Think metal cup full of boiling water, then just wrap it in a couple of layers of newspaper. The paper will get just as hot as the metal, but because it has both a lower specific heat and a lower rate of heat transfer, you won't burn your hands.
The same principle applies while coating the inside of the intake - even though the epoxy (or whatever coating you decide on) will eventually reach the same temp as the bare metal, the amount of heat transferred, as measured in calories or BTU's, is much less.
The extreme example, if you ever watch the Discovery Channel, is the guy putting a blowtorch to a cube of space shuttle tile material until it's glowing hot. Then the guy just reaches down with his bare hand and picks up this glowing hot object, but it doesn't burn him because it just doesn't transfer heat.
The same principle applies while coating the inside of the intake - even though the epoxy (or whatever coating you decide on) will eventually reach the same temp as the bare metal, the amount of heat transferred, as measured in calories or BTU's, is much less.
The extreme example, if you ever watch the Discovery Channel, is the guy putting a blowtorch to a cube of space shuttle tile material until it's glowing hot. Then the guy just reaches down with his bare hand and picks up this glowing hot object, but it doesn't burn him because it just doesn't transfer heat.
(possibly the forumlas will not paste into the quote)
quote:
Well, if you want to check my work, go here:
Newton's Law of Forced Convection
The rate of heat transfered to the surrounding fluid is proportional to the object's exposed area A, and the difference between the object temperature Tw and the fluid free-stream temperature .
The constant of proportionality h is termed the convection heat-transfer coefficient. Other terms describing h include film coefficient and film conductance.
Look closely at the above formula. There is no time parameter. The amount of heat transferred is dependent on the area of the surface, not how long it's in contact with it. This is just for the film of air next to the walls of the intake, but the heat still gets into the cylinders.
OK, how much heat gets transferred? Well, using data found on the web at MatWeb and Heat Transfer Coefficient Conversion Factors, it turns out that the h factor in the above equation is equal to
h = 2.360850287 W/(in².°F)
The length of the manifold is what, about 22 inches? And the cross-section of the manifold plenum is an irregular hexagram, but close enough to an equilateral triangle so as to not matter. I'm guestimating the interior of the plenum to be roughly 200 square inches, although if you count the runners it's probably quite a bit more.
I would guess the manifold on my car reaches roughly 140 degrees by the end of a drag race - too hot to touch comfortably; and if the incoming air is at, say, 80 degrees, then delta-T is 60 degrees. Halving that to account for the intake being nearly at ambient at the start of the race, then the average delta-T is 30 degrees. So plugging all that into Newton's equation, you come up with roughly 14,000 watts of heat going back into the engine. Divide that by 740 watts per horsepower and you get about 19 horsepower.
So, just doing a rough estimate, there are 19 horsepower being lost, on average, because of air being heated by the intake manifold. Based on my ET and mph improvements, I'd guess I'm recovering roughly 10-12 horsepower by coating the inside of the intake. Somebody who road races would see an even bigger improvement.
--------------------
Stonebreaker
355 ci
11.99 at 115mph on 150 hp nitrous
2002 ECIRS CHAMPION
Newton's Law of Forced Convection
The rate of heat transfered to the surrounding fluid is proportional to the object's exposed area A, and the difference between the object temperature Tw and the fluid free-stream temperature .
The constant of proportionality h is termed the convection heat-transfer coefficient. Other terms describing h include film coefficient and film conductance.
Look closely at the above formula. There is no time parameter. The amount of heat transferred is dependent on the area of the surface, not how long it's in contact with it. This is just for the film of air next to the walls of the intake, but the heat still gets into the cylinders.
OK, how much heat gets transferred? Well, using data found on the web at MatWeb and Heat Transfer Coefficient Conversion Factors, it turns out that the h factor in the above equation is equal to
h = 2.360850287 W/(in².°F)
The length of the manifold is what, about 22 inches? And the cross-section of the manifold plenum is an irregular hexagram, but close enough to an equilateral triangle so as to not matter. I'm guestimating the interior of the plenum to be roughly 200 square inches, although if you count the runners it's probably quite a bit more.
I would guess the manifold on my car reaches roughly 140 degrees by the end of a drag race - too hot to touch comfortably; and if the incoming air is at, say, 80 degrees, then delta-T is 60 degrees. Halving that to account for the intake being nearly at ambient at the start of the race, then the average delta-T is 30 degrees. So plugging all that into Newton's equation, you come up with roughly 14,000 watts of heat going back into the engine. Divide that by 740 watts per horsepower and you get about 19 horsepower.
So, just doing a rough estimate, there are 19 horsepower being lost, on average, because of air being heated by the intake manifold. Based on my ET and mph improvements, I'd guess I'm recovering roughly 10-12 horsepower by coating the inside of the intake. Somebody who road races would see an even bigger improvement.
--------------------
Stonebreaker
355 ci
11.99 at 115mph on 150 hp nitrous
2002 ECIRS CHAMPION
03-21-2007, 06:33 AM
#34
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Join Date: Jun 2005
Location: Brandon, Fla.
Posts: 387
I had my manifold coated. Swain Technology did it. They applied their thermal barrier coating (TBE) to the bottom and their heat emitting coating (BBE) to the top. Their tech department told me that their tests have shown a 10 deg drop in intake temperature by doing that. Check this out http://www.swaintech.com/store.asp?pid=10965
The coatings have been on there about 3 or 4 years now; had the manifold off recently with no signs of any flaking or peeling.
I don't know if you can measure any performance gains, but the cooler intake charge can't hurt.
The coatings have been on there about 3 or 4 years now; had the manifold off recently with no signs of any flaking or peeling.
I don't know if you can measure any performance gains, but the cooler intake charge can't hurt.
03-21-2007, 08:44 AM
#36
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Join Date: Jun 2003
Location: Carol Stream, Il.
Posts: 3,557
I had my manifold coated. Swain Technology did it. They applied their thermal barrier coating (TBE) to the bottom and their heat emitting coating (BBE) to the top. Their tech department told me that their tests have shown a 10 deg drop in intake temperature by doing that. Check this out http://www.swaintech.com/store.asp?pid=10965
The coatings have been on there about 3 or 4 years now; had the manifold off recently with no signs of any flaking or peeling.
I don't know if you can measure any performance gains, but the cooler intake charge can't hurt.
The coatings have been on there about 3 or 4 years now; had the manifold off recently with no signs of any flaking or peeling.
I don't know if you can measure any performance gains, but the cooler intake charge can't hurt.
03-22-2007, 12:39 PM
#37
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Join Date: Jul 2002
Location: Friendswood, TX, USA
Posts: 3,769
I'd guess I'm recovering roughly 10-12 horsepower by coating the inside of the intake.
Now they didn't specifically coat just the intake but did just about everything else. Anitfriction, Oil Shedders, and Thermal Barriers(pistons and valves).
With all this they only saw an 8.1hp increase from 550.9hp to 559hp. And it cost them $1061.00 for all the coatings.
Doesn't sound very cost effective to me!!
Last edited by Z28SORR; 03-22-2007 at 02:51 PM.
03-22-2007, 01:06 PM
#38
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Join Date: Jun 2003
Location: Carol Stream, Il.
Posts: 3,557
Back in Dec. Hot Rod did some test on coatings using a 550.9hp LS engine.
Now they didn't specifically coat just the intake but did just about everything else. Anitfriction, Oil Shedders, and Thermal Barriers(pistons and valves).
With all this they only saw an 8.1hp increase from 550.9hp to 559hp. And it cast then $1061.00 for all the coatings.
Doesn't sound very cost effective to me!!
Now they didn't specifically coat just the intake but did just about everything else. Anitfriction, Oil Shedders, and Thermal Barriers(pistons and valves).
With all this they only saw an 8.1hp increase from 550.9hp to 559hp. And it cast then $1061.00 for all the coatings.
Doesn't sound very cost effective to me!!
03-22-2007, 01:36 PM
#39
Registered User
Join Date: Mar 2005
Location: Aurora, IL
Posts: 12,312
Back in Dec. Hot Rod did some test on coatings using a 550.9hp LS engine.
Now they didn't specifically coat just the intake but did just about everything else. Anitfriction, Oil Shedders, and Thermal Barriers(pistons and valves).
With all this they only saw an 8.1hp increase from 550.9hp to 559hp. And it cast then $1061.00 for all the coatings.
Doesn't sound very cost effective to me!!
Now they didn't specifically coat just the intake but did just about everything else. Anitfriction, Oil Shedders, and Thermal Barriers(pistons and valves).
With all this they only saw an 8.1hp increase from 550.9hp to 559hp. And it cast then $1061.00 for all the coatings.
Doesn't sound very cost effective to me!!
03-22-2007, 07:28 PM
#40
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Join Date: Oct 2006
Location: Rochester Hills, MI
Posts: 747
more to the caution when interpreting future tests...... another quote from Randy Stone....
And more from Randy Stone concerning his WAG on the actual horsepower lost from intake air charge heating. I think it'a a very good wild *** guess and somewhat conservative.
(possibly the forumlas will not paste into the quote)
quote:
And more from Randy Stone concerning his WAG on the actual horsepower lost from intake air charge heating. I think it'a a very good wild *** guess and somewhat conservative.
(possibly the forumlas will not paste into the quote)
quote:
The right way to solve it, oversimplified and ignoring effects on ignition timing, fuel vaporisation, etc, is to figure the air temperature change's effect on mass airflow into the engine. Hotter air>less air>less HP.
03-23-2007, 08:42 PM
#41
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Join Date: Feb 2000
Location: Lexington Park, Maryland, USA
Posts: 473
Also lets not forget one bennefit to cooler intake air. . .. Cooler intake air makes the LT1 engine less prone to detonation.
What we need is an intake manifold made of a composite, resin, epoxy, plastic. Something like the LSX manifold.
Karl
What we need is an intake manifold made of a composite, resin, epoxy, plastic. Something like the LSX manifold.
Karl
03-24-2007, 12:12 AM
#42
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Join Date: Jul 2005
Location: Baton Rouge, LA
Posts: 747
Fiberglass intake manifolds are quite easy to make, you just need a base. I really need to pick up a couple extra LT1 intakes so I can try some of these things. Coat one. Grind another down and make a fiberglass intake out of it.
03-24-2007, 07:31 AM
#43
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Join Date: Jul 2001
Location: Double Oak TX
Posts: 752
Also bit on the thermo coating the underside of the intake (twice) and frankly think it's a scam. Didn't make any difference at all except perhaps (this is a pure guess) delaying the onset of heatsoak a tiny bit. The dyno said nada on any real gains and still playing with my sheetmetal intake with a huge air gap to see if it really makes any more power.
The front of the sheetmetal intake stays "warm" from what we believe is new air comming in to the rear cylinders but the back section still get hot with a 3.5 inch gap with the hood open or closed. Dunno???........but for sure on a stock intake it's a waste of money.
03-24-2007, 08:15 AM
#44
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Join Date: Jun 2003
Location: Carol Stream, Il.
Posts: 3,557
Hey Denny, if it's one thing I'm good at, it's wasting money!! But like I said, it was only $100, so no big deal. If it's true, that it didn't help coating the intake so be it. Iv'e made bigger mistakes than that, in trying to find a good combo. 
03-24-2007, 12:44 PM
#45
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Join Date: Jul 2005
Location: Baton Rouge, LA
Posts: 747
I have some sheetmetal, a brake and a set of vortec heads/block i'm going to start making a baseplate out of steel for fabbing up a fiberglass intake manifold and use the heads/block for the angles. If someone can get me an accurate drawing of the LT1 heads I can cut the plate up and actually make one. Though itl'l be a while before I test it.