Got results that I had not anticipate, fyi, Enjoy. WOODY

Lets take a trip and since I invited you, youll have to roll the way I go, so don’t get in my face about specifics as it is a thought experiment and close is good enough; buckle up and keep hands inside the moving vehicle.

Drive a srt with a dual inlet at about 60 steady, and have a 90 degree day, Iam going to say its about 2000 rpm which is 1000cyclinder filling per minute. A liter is about 61 cu. And the motor is 3.2 liters so in a minute were doing 1000 fillings at 3.2 liters times 61 or about
61,000 x 32. or about 195,000 cu. in. Per minute. Divide by 1728 cu. In. per cu ft. and you get 112 cu ft of air per minute.

Now the intake manifold pressure about 15 inches of Hg pressure or ½ atmospheric pressure in this example reduces the actual inlet air flow to about ½ of the 112 cu ft above. That’s 112/2 or 61 cu ft per minute going into the engine or 61cu ft /2 about 30 cu ft of air per minute / PER INLET pipe on the DCAI inlet system.

Ok so the engine is breathing about 30 cu ft of air per inlet per minute. The pipe is 3” in diameter or 1.5 squared, times pi: or 7 square inches of cross section. 30 cu ft of air are 30 x 1728 = 51840 cu in and divided by 7= 7405 inches of flow per minute or divide by 12 = 617 feet per minute. Now divide by 60 and you get an air speed in one of the DCAI tubes of about 10 feet per second or 5280 ft divided by 10 = 528 seconds per mile or 528 divide by 60 = about 9 miles per mile.

Thus the air flow in the inlet system is about 9 mph or 10 feet per second and the air going into the engine goes thru about 4 – 5 feet of pipe in about ½ second. The pipes temperature has ½ second to pick up heat during this time

AT full throttle your turning the engine 3 times as fast and breathing twice as deeply thus 6 times more air TIMES YOUR BOOST in BAR. So if your at 14.7 psi boost your intake is 6 x 2 or 12 times the air flow which reduces the time dwelling in the intake to 1/12 that of the 60 mph example above. 1/12 of ½ sec. is 1/24 of a second or about 0.04 seconds = 40 milliseconds.

What this did for me is to indicate that the inlet pipe heating is minimal during driving and next to nothing in wide-open throttle. The air cannot heat up enough to matter once you punch the throttle

As soon as you punch it the airflow picks up and there is minimal heating AND up to 15 times as much flow to scrub or cool the heat out of the inlet piping. Before the math analysis, I though there was more on the table to be had in this insulation of the inlet

So we have arrived back at reality and Ill work on foam mylar insulation on my inlet for what it is worth. FYI just to let you know I measured my INSULATED inlet pipe to be at 140 degrees at 60 mph cursing on a 90 degree day - THIS IS NOT THE AIR FLOW AS I DID NOT PUT THE PROBE INSIDE THE PIPE FOR THIS TEST SEQUENCE. Nother day.

ENJOY, WDY

 

Yea: What he said.
Ken

 

And that is why I call him professor....lol. You wouldn't be close to Alexandria would you Woody. Need someone to look at a gray one for a friend. Thanks.....

 

Sorry doc thats an hour inside the suicide circle and I dont venture in that region its like fairfax and stuff - not good for me to be in there. ww Iam about 40 west of dc. Wdy

 

thanks Woody. working on getting rear gear change.... early stages, but I think we will get it done yet this year...carry on...

 

Just starting to digest the math. Since we have a 4-cycle motor wouldn't the filling at 2000rpm be 500 and not 1000? Intake, compression, firing and exhaust. So recauculate?

 

Just starting to digest the math. Since we have a 4-cycle motor wouldn't the filling at 2000rpm be 500 and not 1000? Intake, compression, firing and exhaust. So recaculate?

IF the engine pistons WERE displacing 112 cubic feet it had better receive 112 cubic feet of air, minus the fuel volume. Since the intake manifolds are at 1/2 atmospheric, remember there are 2 of them, so the the motor is in fact taking in the 112 cubic feet per minute and not the 61 cubic feet stated, staying with the figures in the original post, but 61 cubes feet per inlet pipe, not about 30. So there are 60 CFM in EACH manifold/pipe.

The 4th paragraph confuses me as it seems to take cubic feet and then they become linear. I estimate each inlet pipe at 4' long from my bed. that means each has 340 cubic inches of volume, divided by 1728, cubic inches be square feet equals .2 cubic feet rounded up from .19675. If indeed each pipe is drawing in 62 cubic feet a minute then that is roughly 1 cubic foot per second(62/60)Since the pipes volume is only .2 cubic feet we'll see that we have to multiply times 5 to get the 1 cubic foot of volume per second. That means 1/5 of a cubic foot can occupy the pipe in any given time, so the 1 cubic foot is sped up 5 times to all get through in 1 second. Then how fast would atmospheric move air through a 3" diameter pipe assuming no friction, much comes into play, physics.

What I am getting at here waldig is I believe the math is skewed and then we have the physics involved making mathematical assessments about a non-insulated pipe compared to an insulated pipe very difficult to determine. A datalog using uninsulated and then insulated pipes on the same day within the least amount of time on a warm motor would still be the best way to judge the value of the insulation. It's not just the amount of time the inlet air is in each pipe but how much the pipes inside diameter is transferring the heat. Again, much physics involved, especially if the car has that wonderful killer chiller. It's likely that it takes more heat(energy) to raise 1 cubic foot of air that is 60* Farenheit to start with 1*(put any figure here) then raising 1 cubic foot of air 1* that is 100* Farenheit.
I know the Cobra Mustangs measured inlet temps at the MAF, right after the filter and then in the compressor. There must have been some correlation that the ECU then determined was going on in the inlet air from start to near finish.

I know the temp of my braiin has increased, likely destroying or harming what good cells I have left after 62 years, many spent in abusing the brain!

Really the better media for a CAI is plastic or carbon fiber IMHO, mark

 

While aluminum does transfer heat more than plastic or carbon fiber, since heat travels in waves much like light it also reflects heat away so maybe polished aluminum would be better. It would be an interesting experiment! Maybe the Ultra Gauge could be used to shed some light on this.

 

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Default Re: I did a study of inlet pipe insulation and SUPRISE

Just starting to digest the math. Since we have a 4-cycle motor wouldn't the filling at 2000rpm be 500 and not 1000? Intake, compression, firing and exhaust. So recaculate?

engine intake is half or cyclinders per revolution, one revolution is one up and one down of piston or 1/2 of the 4 cycle.



IF the engine pistons WERE displacing 112 cubic feet it had better receive 112 cubic feet of air, minus the fuel volume. Since the intake manifolds are at 1/2 atmospheric, remember there are 2 of them, so the the motor is in fact taking in the 112 cubic feet per minute and not the 61 cubic feet stated, staying with the figures in the original post, but 61 cubes feet per inlet pipe, not about 30. So there are 60 CFM in EACH manifold/pipe.

See above, the intake air is also at 1/2 atmospheric density so the intake of atmospheric air volume is only 1/2 of air consumed , cause it expands in the manifold after the tb.

The 4th paragraph confuses me as it seems to take cubic feet and then they become linear. I estimate each inlet pipe at 4' long from my bed. that means each has 340 cubic inches of volume, divided by 1728, cubic inches be square feet equals .2 cubic feet rounded up from .19675. If indeed each pipe is drawing in 62 cubic feet a minute then that is roughly 1 cubic foot per second(62/60)Since the pipes volume is only .2 cubic feet we'll see that we have to multiply times 5 to get the 1 cubic foot of volume per second. That means 1/5 of a cubic foot can occupy the pipe in any given time, so the 1 cubic foot is sped up 5 times to all get through in 1 second. Then how fast would atmospheric move air through a 3" diameter pipe assuming no friction, much comes into play, physics.

inlet air velocity in the dcai pipe would be volume of flow divided by the cross section of the pipe. I stand on 30 cu ft and thus 30 cu ft x 1728 cu in / cu ft divided by the pipes area of 7sq in would give the air velocity in inches per minute divide by 12 is ft per min. which I figured to be 10 ft per min.

I could have done the speed conversion better. air speed in one of the DCAI tubes of about 10 feet per second or 5280 ft divided by 10 = 528 seconds per mile or 528 divide by 60 = about 9 miles per mile. = = fail it would be 9 minutes per mile and more calculations needed.

SO if 88 ft /second is 60 mph then, ( 10/88 ) x 60 = 6.8mph

What I am getting at here waldig is I believe the math is skewed and then we have the physics involved making mathematical assessments about a non-insulated pipe compared to an insulated pipe very difficult to determine. A datalog using uninsulated and then insulated pipes on the same day within the least amount of time on a warm motor would still be the best way to judge the value of the insulation. It's not just the amount of time the inlet air is in each pipe but how much the pipes inside diameter is transferring the heat. Again, much physics involved, especially if the car has that wonderful killer chiller. It's likely that it takes more heat(energy) to raise 1 cubic foot of air that is 60* Farenheit to start with 1*(put any figure here) then raising 1 cubic foot of air 1* that is 100* Farenheit.

I did the full test with one inlet insulated and the passenger inlet uninsulated at the same time, so there was a reading just before the supercharger inlet showed the difference in pipe temperatures to evaluate the insulation. I just insulated the passenger side last night and will have it on soon. the testing was to see if the pipes were going to profit from the insulation and to my suprise the pipes wernt being cooled much, why??

well the air is not going thru fast enough to scrub out much heat for the reasons stated.


I know the Cobra Mustangs measured inlet temps at the MAF, right after the filter and then in the compressor. There must have been some correlation that the ECU then determined was going on in the inlet air from start to near finish.

Our inlet air temp is at the outlet of the intercooler and thus way down from the intake manifold. I wanted to reduce or limit the temp of the incoming air to maximize the charge density going into the supercharger. Everything after that is fixed by the configuration of the sc and ic designs.

I know the temp of my braiin has increased, likely destroying or harming what good cells I have left after 62 years, many spent in abusing the brain!

Really the better media for a CAI is plastic or carbon fiber IMHO, mark

I agree and think a low conductivity carbon fiber pipe would be the deal, as it would be an insulator.

WW at 68 yrs.

 

Aaaahhhh-the difference between an engineer and a physicist:

engineers toast themselves for a 50% improvement.

Physicists ignore less than an order of magnitude delta as "statistics".

Waldo's on the right track. I made these same measurements (on my N/A) 5-6 years ago.

Same results. Look it up. The heatsoak the SC guys observe is a bit more problematic-more mass to hold more energy (heat).

And how to remove it.

JEFASOLD-polishing the exterior of the aluminum pipes gains little. It may make them reflect visible light better, but has little effect on infrared. It's a wavelength thing. That's why that neat gold-faced NASA stuff I used is so cool: 97.2% reflection. And a really thin (.005") fiberglass matt inside.

Waldo's also corect in that the only true measure of the insulated pipe vs. uninsulated is a tc in the airflow.

4 of them: one each in the input ends and one each in the output ends. measure delta T and contemplate.

Nice work Professor. You must be one of the 5%. I work with them. This is the figure I came up with that reflects how many are with a pinch of ****.

 

Doesn't this make the Devils Horns look more like a waste of money, what with the air backing up in the inlets?
It would be like sending more cars down a four lane highway with two lanes blocked.

 

Id think that youd need to use a pressure gauge to see the difference -gain - at normal speed.

I did that in the army on my chevy 4 banger and got a gain at 60 but it was made up out of coke cans sectioned and taped together with scotch tape to form the tubing/ piping.

I was very poor and had time on my hands so coke can tubing on a one barrel carb was my way of experimenting. could cut the can with scissors and tape was available and it was sorta cold ( can ) air inlet with a scoop to catch air. YOUTH!!!!

 

I've been trying to point this out for...5-6 years.

"Great minds tend to follow similar paths...".

 

Since my SLK has more limitations for cooling the intake charge(killer chiller) I will insulate my DCAI pipes and post any difference in the IAT's. I still prefer the actual results rather than the mathematics involved. best wishes, mark

 

Depending on conditions in traffic and driving speed I measured 6 to 10 degree cooler inlet pipes after the mylar bubble insulation.

I have now insulated both pipes and will be taking a measurment of the pipe temp and the AIR INSIDE it. I placed a surface probe under the insulation to measure the insulated pipe and POKED a thermal probe into the rubber elbow to be able to sense the air entering my supercharger.

This way I can see how the AIR temp is affected as it goes thru the filter and inlet pipe, and Ill pass the results on to the forum.

WDY

 

There you go!

 

Hi Woody, Any chance I could visit you one afternoon? I live in Springfield va (u know, where the Simpsons live LOL)

 

Weekends work, saturday is best and advance planning works best. Gainesville va is the location. awood eye at gma il dot c om. WDY

 

THANKS! mark

 

Its too late to start writing it up but the results were most illuminating and down right upsetting. My inlet air is running at 130 on a 92 degree day!!!!!!!!!!!!!!!!! this is after insulating both pipes.

I believe the throttle bodies are being heated by the radiators air flow................ To move the probes to the inlet its self and see after the throttle body............... There is gold somewhere in this. Ill find it. Woody

Please not get confused as the inlet air temp is VERY different from IAT. Iam measuring the air going INTO the supercharger and recording the temps.

IAT is the temp after the supercharger and intercooler and measured BEFORE going into the intake manifolds.

I want cooler air going into the supercharger to raise the boost; by injesting denser air. 130 degrees is not it, and another suprise to me