Wrapped my intake tubes with heat reflective tape.
08-17-2010 | 04:55 PM
#47
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From: DFW Texas
As I read these posts, it occured to me that the radiator shroud, both the aluminum one and the fiberglass one could be making the stock system into a better cold air intake. It may well be that all the improvement in temps was due to the shroud. All my temp readings were done with 100% stock vs full mods. IE. inlet tubes and air cleaner housing insulated and the aluminum shroud in place.
I feel my data is accurate and spread over a long enough period of time and accounted for various traffic conditions. I did not do any dyno runs with the 89GT. I also discounted the ***-o-meter difference.
I feel my data is accurate and spread over a long enough period of time and accounted for various traffic conditions. I did not do any dyno runs with the 89GT. I also discounted the ***-o-meter difference.
08-17-2010 | 05:00 PM
#48
Drifting
Joined: Jun 2006
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From: Indianapolis Area
Jim let me see if I got this straight. You are suggestion that with your experiment on an unmodified car, the air temperatures raises twenty something (to max 31) degrees in the quarter second it takes to get from the front of the radiator to the air box? I think all things being equal except for the modifications that would be hard to reproduce.
Maybe a better way would be to measure the temperature differential between what is enters and exits the tubes. I think what MK is suggesting is the difference from entrance to the exit is insignificant if even measurable. Taking measurements on one end and not simultaneously doing the same thing on the other end sure isn’t going to prove anything me. Although, I would like a way to read and monitor intake charge temps now that mine is boosted.
Also, I do have to say the intake on the front sure does looks nice. Just the bling factor is worth the cost of admission on that piece.
_________________________________________________________
Edit... this was written before your last post which clarified a few things.
Maybe a better way would be to measure the temperature differential between what is enters and exits the tubes. I think what MK is suggesting is the difference from entrance to the exit is insignificant if even measurable. Taking measurements on one end and not simultaneously doing the same thing on the other end sure isn’t going to prove anything me. Although, I would like a way to read and monitor intake charge temps now that mine is boosted.
Also, I do have to say the intake on the front sure does looks nice. Just the bling factor is worth the cost of admission on that piece.
_________________________________________________________
Edit... this was written before your last post which clarified a few things.
Last edited by auzivision; 08-17-2010 at 05:04 PM. Reason: updated
08-17-2010 | 05:19 PM
#50
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From: In a tizzy
If insulating the tubes makes such a big difference then why don't cold air intake kits come with insulated tubes?
How about running a couple of little scoops and tubing up from the bumper openings to the inlets above the radiator to direct air to the inlets? The 944 Turbo has scoops to direct air from the bumper opening to the intercooler. Makes a big measured difference in intercool effectiveness.
How about running a couple of little scoops and tubing up from the bumper openings to the inlets above the radiator to direct air to the inlets? The 944 Turbo has scoops to direct air from the bumper opening to the intercooler. Makes a big measured difference in intercool effectiveness.
08-17-2010 | 05:24 PM
#51
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Three Wheelin'
Joined: Apr 2010
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From: Virginia Beach, VA
If insulating the tubes makes such a big difference then why don't cold air intake kits come with insulated tubes?
How about running a couple of little scoops and tubing up from the bumper openings to the inlets above the radiator to direct air to the inlets? The 944 Turbo has scoops to direct air from the bumper opening to the intercooler. Makes a big measured difference in intercool effectiveness.
How about running a couple of little scoops and tubing up from the bumper openings to the inlets above the radiator to direct air to the inlets? The 944 Turbo has scoops to direct air from the bumper opening to the intercooler. Makes a big measured difference in intercool effectiveness.
This is originally what I wanted to do, but couldn't see any good way to route air through the bumper. Where would you bring the air through?
08-17-2010 | 05:26 PM
#52
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From: saratoga, ca
08-17-2010 | 05:26 PM
#53
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Three Wheelin'
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From: Virginia Beach, VA
The heat soak that I'm trying to combat is solely from sitting at traffic lights. Lots of long traffic lights here in Va Beach. So far, this new wrap is working as advertised. Just got back from an hour long drive through the city, the car didn't show weakness pulling away from lights like before.
08-17-2010 | 05:32 PM
#54
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From: saratoga, ca
Jim, your restriction of the air to get to the intake ducts would easily be worth the temp drop, IF any could be found. having done flow analsys in those kind of configurations, that flap would cause havok on air flow to enter the inlets. in fact, so much so that it might draw from the seems to the side, getting the engine bay air. 
what reading??? please tell. in traffic, where your air flow is near O, and you have plenty of time for the intake tubes to become heat soaked? so what is the point. remember, its all like a bake potato once everything gets up to temp.
AND also remember , transient time of the air entering the inlets over the 2" radiator top. we are talking 25-30mph air here. Over a 2" spread? the face of the radiator will get no flow over it, in fact, its pressure differential is pushing air through the face of the radiator. so somethings things are not all that they may seem. give us an air box temp at operating tempurature. (top of the filter at WOT) then, pull all that nonsense off the tubes and the front of the engine. do a WOT run. trust me, you will find NO measureable difference.
what reading??? please tell. in traffic, where your air flow is near O, and you have plenty of time for the intake tubes to become heat soaked? so what is the point. remember, its all like a bake potato once everything gets up to temp.
AND also remember , transient time of the air entering the inlets over the 2" radiator top. we are talking 25-30mph air here. Over a 2" spread? the face of the radiator will get no flow over it, in fact, its pressure differential is pushing air through the face of the radiator. so somethings things are not all that they may seem. give us an air box temp at operating tempurature. (top of the filter at WOT) then, pull all that nonsense off the tubes and the front of the engine. do a WOT run. trust me, you will find NO measureable difference.
As I read these posts, it occured to me that the radiator shroud, both the aluminum one and the fiberglass one could be making the stock system into a better cold air intake. It may well be that all the improvement in temps was due to the shroud. All my temp readings were done with 100% stock vs full mods. IE. inlet tubes and air cleaner housing insulated and the aluminum shroud in place.
I feel my data is accurate and spread over a long enough period of time and accounted for various traffic conditions. I did not do any dyno runs with the 89GT. I also discounted the ***-o-meter difference.
I feel my data is accurate and spread over a long enough period of time and accounted for various traffic conditions. I did not do any dyno runs with the 89GT. I also discounted the ***-o-meter difference.
08-17-2010 | 05:35 PM
#55
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From: saratoga, ca
Put down the crack pipe! Look, you cant tell anything just driving around town, part throttle. there are so many variables to what you think you are doing, its not even funny. all you need to do is go to the dyno. Put an end of this nonsense. you cant combat heat soak, no more than you can keep a bake potato from baking in an oven with this coating. try it. it might take 5mins longer.
The heat soak that I'm trying to combat is solely from sitting at traffic lights. Lots of long traffic lights here in Va Beach. So far, this new wrap is working as advertised. Just got back from an hour long drive through the city, the car didn't show weakness pulling away from lights like before.
08-17-2010 | 05:40 PM
#56
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From: saratoga, ca
exactly! they dont because its a dumb idea. waste of time and will not work, due to the transient time of the air moving through it.
Now, for your second thougt, thats what we DO have already. just below the bumper, ive measured 11psi at 120mph, which is near the same as the bumper. the air moves through the radiator due to this large pressure differential. it doest run along the radiator and then enter the air inlets. all that air is ambient or cold air. I race for 2 laps at the track, pull into the hot pits and my 260 degree oil, near boiling water temps and my air intake that is heat sunk to the heads, is cool to the touch.. Hmmmmm, why???? because the heat in the engine is no match to the flow rate into the engine..
mk
Now, for your second thougt, thats what we DO have already. just below the bumper, ive measured 11psi at 120mph, which is near the same as the bumper. the air moves through the radiator due to this large pressure differential. it doest run along the radiator and then enter the air inlets. all that air is ambient or cold air. I race for 2 laps at the track, pull into the hot pits and my 260 degree oil, near boiling water temps and my air intake that is heat sunk to the heads, is cool to the touch.. Hmmmmm, why???? because the heat in the engine is no match to the flow rate into the engine..
mk
If insulating the tubes makes such a big difference then why don't cold air intake kits come with insulated tubes?
How about running a couple of little scoops and tubing up from the bumper openings to the inlets above the radiator to direct air to the inlets? The 944 Turbo has scoops to direct air from the bumper opening to the intercooler. Makes a big measured difference in intercool effectiveness.
How about running a couple of little scoops and tubing up from the bumper openings to the inlets above the radiator to direct air to the inlets? The 944 Turbo has scoops to direct air from the bumper opening to the intercooler. Makes a big measured difference in intercool effectiveness.
08-17-2010 | 05:46 PM
#57
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From: saratoga, ca
exactly.
So, that is an interesting idea. just a tempurature test, under full heat soaked conditions. one side vs the other stock, unmodified side. see if you get a tempurature difference between the two sides.
another thought based on the pics. no one has really sealed their air boxes. Ive seen a lot of leaks in the air box that were fixed by really sealiing up the air box. this means, before sealing, the air under WOT was not even filtered air.
I measured. 25psi vacuum on the air box back of the filter. sealed, it went to .5psi vacuum. (I think it was .5" Hg vs 1" hg, as it has been a long time) the net net of that test was when the air boxe was sealed , the vacuum went up, due to the air going though the tubes. otherwise, it was leaking through the cracks.
want to improve the system, find a way to vent the air box to the base of the windshield and also seal it up better.
So, that is an interesting idea. just a tempurature test, under full heat soaked conditions. one side vs the other stock, unmodified side. see if you get a tempurature difference between the two sides.
another thought based on the pics. no one has really sealed their air boxes. Ive seen a lot of leaks in the air box that were fixed by really sealiing up the air box. this means, before sealing, the air under WOT was not even filtered air.
I measured. 25psi vacuum on the air box back of the filter. sealed, it went to .5psi vacuum. (I think it was .5" Hg vs 1" hg, as it has been a long time) the net net of that test was when the air boxe was sealed , the vacuum went up, due to the air going though the tubes. otherwise, it was leaking through the cracks. want to improve the system, find a way to vent the air box to the base of the windshield and also seal it up better.
Jim let me see if I got this straight. You are suggestion that with your experiment on an unmodified car, the air temperatures raises twenty something (to max 31) degrees in the quarter second it takes to get from the front of the radiator to the air box? I think all things being equal except for the modifications that would be hard to reproduce.
Maybe a better way would be to measure the temperature differential between what is enters and exits the tubes. I think what MK is suggesting is the difference from entrance to the exit is insignificant if even measurable. Taking measurements on one end and not simultaneously doing the same thing on the other end sure isn’t going to prove anything me. Although, I would like a way to read and monitor intake charge temps now that mine is boosted.
Also, I do have to say the intake on the front sure does looks nice. Just the bling factor is worth the cost of admission on that piece.
_________________________________________________________
Edit... this was written before your last post which clarified a few things.
Maybe a better way would be to measure the temperature differential between what is enters and exits the tubes. I think what MK is suggesting is the difference from entrance to the exit is insignificant if even measurable. Taking measurements on one end and not simultaneously doing the same thing on the other end sure isn’t going to prove anything me. Although, I would like a way to read and monitor intake charge temps now that mine is boosted.
Also, I do have to say the intake on the front sure does looks nice. Just the bling factor is worth the cost of admission on that piece.
_________________________________________________________
Edit... this was written before your last post which clarified a few things.
08-17-2010 | 05:51 PM
#59
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Joined: Feb 2003
Posts: 29,817
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From: saratoga, ca
I agree with you too. the sealing of the tubes will be the best bang for the efforts. they leak like you would not believe. they are under some vacuum during WOT operation.
Easy there Mark, if you read my post again you'll see I'm agreeing with you.
You said CAI works. I'm saying that maybe they sealed out the inevitable under-hood air that gets into the stock setup when those flimsy plastic tubes are pushed into the ends of the air box when they taped them on. (on at least one there is a rad cover as well).
You said CAI works. I'm saying that maybe they sealed out the inevitable under-hood air that gets into the stock setup when those flimsy plastic tubes are pushed into the ends of the air box when they taped them on. (on at least one there is a rad cover as well).
08-17-2010 | 06:08 PM
#60
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From: saratoga, ca
Mark I think your idea that heat soak will negate the benefit is incorrect. Not that there is necessarily enough dwell time in the tube for the ID tube temp to have a profound effect on IAT. The thermal wrap on the tube will most likely reduce the ID temp of the tube. This is due to the reduced thermal conductivity of the insulated tube. I think you are being distracted by the idea of heat soak. Maybe another example will help clarify (or just ad to the confusion, we’ll see). This example will hopefully be easy to identify with.
Example:
Take a thermos (one of the nice stainless steel ones) and fill it with hot water just below its boiling point. Put the lid on it and set it on the table.
Now Take a nice quart sized stainless steel pan and fill it with hot water as well, put a lid on it and set it on the table next to the thermos.
Now wait a few minutes or so, enough time for thermal equilibrium (heat soak) to occur.
With out using the handles (insulated to keep you from burning your hands) pick each one up.
You will most likely notice that pan is painful to hold, where the thermos is most likely warm but unlikely to cause you harm.
The decrease in thermal conductivity allows for a greater change in temperature across the insulated material as equilibrium. This is similar to what is happening when the intake tubes are wrapped with insulation. The outside of the insulation reaches equilibrium at a temperature close to that of the engine bay and the ID of the tube reaches an equilibrium temperature closer to that of the intake air. As the insulating value decreases (or thermal conductivity increases) the ID and OD temps more towards each other OD temp goes down and ID temp goes up.
So, if you are trying to minimize heat input in to the intake air you want an intake system with the maximum insulating value you can have any time the temperature around the OD of the system is higher then the intake air temp.
A few materials in order of conductivity
High conductivity
Copper
Aluminum
Steel
Titanium
Plastic
Fiber Glass
Low conductivity.
This is why radiators are typically made of copper or aluminum,
Fiber glass is used to insulate things such as headers and you attic
And why we wear coats in the winter.
Example:
Take a thermos (one of the nice stainless steel ones) and fill it with hot water just below its boiling point. Put the lid on it and set it on the table.
Now Take a nice quart sized stainless steel pan and fill it with hot water as well, put a lid on it and set it on the table next to the thermos.
Now wait a few minutes or so, enough time for thermal equilibrium (heat soak) to occur.
With out using the handles (insulated to keep you from burning your hands) pick each one up.
You will most likely notice that pan is painful to hold, where the thermos is most likely warm but unlikely to cause you harm.
The decrease in thermal conductivity allows for a greater change in temperature across the insulated material as equilibrium. This is similar to what is happening when the intake tubes are wrapped with insulation. The outside of the insulation reaches equilibrium at a temperature close to that of the engine bay and the ID of the tube reaches an equilibrium temperature closer to that of the intake air. As the insulating value decreases (or thermal conductivity increases) the ID and OD temps more towards each other OD temp goes down and ID temp goes up.
So, if you are trying to minimize heat input in to the intake air you want an intake system with the maximum insulating value you can have any time the temperature around the OD of the system is higher then the intake air temp.
A few materials in order of conductivity
High conductivity
Copper
Aluminum
Steel
Titanium
Plastic
Fiber Glass
Low conductivity.
This is why radiators are typically made of copper or aluminum,
Fiber glass is used to insulate things such as headers and you attic
And why we wear coats in the winter.
Perception versus reality can get blurred with expectations.
I agree it could be something else, but will never agree that the air in the intakes has enough time to heat up significantly enough to make a real measurable difference.
Then again, if it makes someone feel better doing it, there is nothing wrong with that.
I agree it could be something else, but will never agree that the air in the intakes has enough time to heat up significantly enough to make a real measurable difference.
Then again, if it makes someone feel better doing it, there is nothing wrong with that.
Once again the all knowing MK is letting his big mouth overrun his brain.
I measured my temps at the top of the stock aircleaner using a Fluke digital probe, accurate to 1/2 degree F. I took my measurment over about a 4 week period both before and after my mods. Measured it in the mornings on the way to work, and again on the way home, recorded the temp of the Fluke and the outside thermometer on the car. Any inaccuracy in the Porsche temp gauge is irrevelent since I was only interested in the difference. However my temp gauge has always been close to radio reports. All measurments were done at highway speed, althought my notes show temps in the high 170's when stopped in traffic. These quickly cooled down when I got going again.
The 31F drop was after the insulation addition compared to before the insulation addition on similiar ambient temp days. Some days I didn't get to 31, but most times in the mid to high 20's in temp drops.
The point of all this is; there is some heat gain to the inlet air from engine temps and sucking air from the top of the radiator even while driving. Originally I had a piece of aluminum to shroud the radiator, but it became so heat soaked that it would burn your hand and I felt it wasn't accomplishing anything. On my GTS I built the fiberglass shroud to go over the top of the radiator. Now my inlets draw air from in front of the radiator without the added heat, and the fiberglass doesn't get nearly as hot as the aluminum one did.
I did my measurments based on some tests Louie Ott did to accomplish similar results. Those of you who know "Professor" Ott know he is through with his analysis.
I measured my temps at the top of the stock aircleaner using a Fluke digital probe, accurate to 1/2 degree F. I took my measurment over about a 4 week period both before and after my mods. Measured it in the mornings on the way to work, and again on the way home, recorded the temp of the Fluke and the outside thermometer on the car. Any inaccuracy in the Porsche temp gauge is irrevelent since I was only interested in the difference. However my temp gauge has always been close to radio reports. All measurments were done at highway speed, althought my notes show temps in the high 170's when stopped in traffic. These quickly cooled down when I got going again.
The 31F drop was after the insulation addition compared to before the insulation addition on similiar ambient temp days. Some days I didn't get to 31, but most times in the mid to high 20's in temp drops.
The point of all this is; there is some heat gain to the inlet air from engine temps and sucking air from the top of the radiator even while driving. Originally I had a piece of aluminum to shroud the radiator, but it became so heat soaked that it would burn your hand and I felt it wasn't accomplishing anything. On my GTS I built the fiberglass shroud to go over the top of the radiator. Now my inlets draw air from in front of the radiator without the added heat, and the fiberglass doesn't get nearly as hot as the aluminum one did.
I did my measurments based on some tests Louie Ott did to accomplish similar results. Those of you who know "Professor" Ott know he is through with his analysis.
Also, the little amount of surface area over the radiator, will transfer very little heat to the intake. So, a little plate over it, made of fiberglass, is not going to do anything either, but then again, how could it? the air flow is going over a 2"wide surface, about 5" long. how much heat can a 170degree plate transfer to a 30mph air flow??? you can answer that, if i seem to be letting my mouth run over my brain.
. If you care about part throttle air temps, sure, that could change, but what is the point. its all about mass flow. you want more mass flow, push down the throttle . do our engines run better during cruise with colder air? I would say not , but thats a good test too. in fact, pre heating the air might make for better combustion, maybe not. Now, that would be a good debate.
But, to claim insulated intake tubes increase power, you have to do all your tests at WOT and on the dyno otherwise you are just talking.