IC and Tubes Delete Theory??

BobGPz

Registered User
What is the point of having the Intercooler and tubes IF??

Just pondering why, So throw in some input if I’m correct OR if I’m wrong, which I probably am, but the Supercharger gets air from the throttle body at roughly 60 to 90 degrees (Depending on outside air temperature). It then blows the air through the top of the SC, out the top IC tube, into the IC where the air is then cooled, (which logically can’t be too much less than the outside temperature). It then gets HEATED back up as it runs through the lower IC tubes which is right next to the exhaust manifold, and back up into the Inlet Plenum, and down the intake manifold. Right?

OK then…What IF the intercooler and tubes were deleted? If you ran a “U” shaped tube from the SC top bending back and down to the Inlet Plenum DIRECTLY??? Would there really be any kind of noticeable drop in horsepower? Maybe even a gain?? Since the air would then come from outside (at outside temperature), then flowing into the TB and to the SC. It would then go out the top of the SC and directly into the Plenum. It would NOT get “Cooled down” through the IC tubes, but can that really lower temps much? Especially with the lower one right next to the exhaust header? Is it not easier to blow through a shorter straw than a longer one? Wouldn’t Boost pressure increase?

Has anybody ever tested the air TEMPERATURE at the lower IC tube just AFTER it comes out of the IC, and then again just BEFORE it goes into the Plenum? This would be very curious…maybe even prove my theory…

Maybe I’m trying to outguess some Ford engineer who has more science, physics, and engineering schooling than I’ll ever have.:D
 
http://www.sccoa.com/articles/cwintercooler.php

Read that to see what kind of temps youre dealing with. Up to 404* F coming out of the supercharger, averaging around 160*. We really need as much cooling as we can get. It was measured in that article that the IC drops that about 50-60*, I seriously doubt the heat from the exhaust manifold is gonna heat it back up that much. If youre worried about the lower tube heating up wrap it in some header wrap or something.

"into the IC where the air is then cooled, (which logically can’t be too much less than the outside temperature)"

Its impossible for an air to air IC to cool to a lower than outside temperature (without an ice tray). You cannot remove heat from something colder than what youre cooling it with.

Not a bad thought, but the IC is important. What Id like to try is a IC with inlet and outlet both on top to avoid the lower tube routing, plus it would have much less pressure drop and more cooling using an aftermarket core.

-Travis
 
That air that is "blown" out of the supercharge and out through the top can reach temps of 400 degress F under high boost levels. I'm positive the intercooler and piping can cool that down a bit!

Some cars with M90s (like the GM's) do run without an intercooler and its piping, but run at lower boost levels. Those also blow directly into the manifold (inverted from our M90).

This older article written by Charles Warner (now of Magnum Powers) will give more technical information:

http://www.sccoa.com/articles/cwintercooler.php
 
Thanks Travis & George

That explains alot. I had no idea the SC got that hot!

I do wonder though if directing fresh incoming air to the SC would also help cool it, resulting in more HP. I notice the SC basically sits on a cradled intake manifold. If it was redesigned a bit, a person could come up with something to direct fresh incoming air to the underneath of the SC as well. I obviously am going to have to look into a bigger IC and a fan then.

Thanks guys...:)
 
Well...the very act of compressing the air causes its temperature to rise. Raising the blower up will not solve the problem since it is basic physics that is at work.

Also the amount of time the air stays in the lower IC on its way to the inlet plenum is very limted at high boost. Convection heating from the exhaust manifolds would add little real heat to the air.
 
Duffy Floyd said:
Well...Raising the blower up will not solve the problem since it is basic physics that is at work.

OK, but having cool air directed under the blower would help cool it resulting in less output air temp...wouldn't it? I never took physics in school, I was too busy chasing skirts...:D
 

Not a bad thought, but the IC is important. What Id like to try is a IC with inlet and outlet both on top to avoid the lower tube routing, plus it would have much less pressure drop and more cooling using an aftermarket core.

-Travis [/B]


I know i have seen this done on this board, someone had a pic of it as their avatar. The stock IC was mounted to the top/front of the blower at a 90º angle. (i think it was the stock ic, or maybe some fab done to it) Im sure whomever is running this set up will probably check out this post and give us some input. It looked pretty efficient to me.
 
Not really since again there would not be enough heat transfered to make a difference. You need surface area and airflow plus a big difference in temperatures to get anything worthwhile and raising the blower is not going to cut it. Those high termperatures quoted only last a short time since most WOT blasts last that long.

As sson as you lift from the WOT blast the supercharger bypass valve opens and you are recirculating air through the blower which will lower termperture of the air charge dramatically.
 
Intercooling 101

Here is an article I wrote about what the IC actually does for us. It is an example of the type of information that will be in the yet to be established members only section of the BBS.



"Here is some theory about exactly what the "IC "does for us. It is based in part on an article on Intercooling I had in an old Hot Rod Magazine "Ford High Performance" book. The interview was written by Tom Hutchinson of Ford's SVO Section.

To understand why an intercooler is such a practical piece of hardware it is essential to review the principles of pressurizing the intake air of an engine. In our case the SC forces the air under pressure through the IC Tubes and IC and ultimately into the engine intake manifold. The force developed is of course called boost pressure which is really a pressure ratio and it simply is a measure of how hard the SC is blowing air into the intake. Mathematically Boost Pressure or Pressure Ratio is expressed as:

Pressure Ratio (PR) = Intake Manifold Pressure Absolute / Inlet Pressure Absolute

(For those of you that forget Absolute Pressure = Atmospheric Pressure + Gauge Pressure (PSIG). Atmospheric pressure at standard conditions is assumed to be about 14.7 PSI)

So if you are running 10 PSI of boost the Pressure Ratio would equal

PR = 14.7 PSI + 10PSIG / 14.7 PSI or 1.68

We know that as the SC spins air is compressed and shoved out the top of the case under pressure. This squeezing action cause an increase in heat since the molecules of air are being packed closer together. It has been reported that we can see outlet temps of around 400 degrees or more than a 5 times increase when compared to normal inlet air temps. We know that generally an engine produces power proportional to how it flows air. More specifically the number of pounds of air mass (PPM=Pounds Per Minute) is what counts in order to determine the air mass value the volume of the air (cfm = cubic feet per minute) must be corrected for density. A general rulle of thumb says that for every 10 degree F temperature rise of inlet air to the engine there is a 1% loss in horsepower.

Lets run some numbers and see under ideal conditions how much heat we can gain with 10 PSI of boost on a say 100 degree day. Probably realistic numbers for a hot summer track day. Remember that as temperature rises the density of the air charge is reduced and HP being produced is going DOWN.

Temp. of the Air Charge (T2) = Inlet Temp. Absolute (T1) X (Manifold Pressure Absolute/Inlet Pressure Absolute) raised to the .283 power

T2 = 100 degrees F + 460 X (14.7 PSIA + 10 PSIG/14.7 PSIA) raised to the .283 power OR

T2 = 560(1.63) raised to the .283 power OR

T2 = 560 X 1.158 =648.6 Degrees R (absolute)

Note: Degrees R are expressed in ther Rankin Temperature Scale which is Degrees F + 460 = Degrees R

T2 = 648.6 degrees R - 460 or 188.6 degrees F

Since we started with 100 degree ambient air and ended up with 188.6 degrees F Inlet Manifold Air the IDEAL Heat rise was 88.6 degrees F. (Meaning the theorically best result we could expect)

With respect to this, a measure of how well a supercharger can pressurize air without giving away the benefits to the resultant temperture rise is termed as Adiabatic Efficiency. Now this is a critical item since the idea here is to make power right?

The ACTUAL Temperature Rise of the air can be determined by the formula

Actual Temperture = IDEAL Temperature Rise / Adiabatic Efficiency.

Here I am going to cheat a tad and use the Eaton Performance Charts for the M90 and actually work the equation backwards to compute the Adiabatic Effiency since the charts on their websize already show a Delta T figure of about 190 degrees F at WOT max RPM.

So the equation becomes

Adiabatic Efficiency = Ideal Temperature Rise / Actual Temperature rise OR

Adiabatic Efficiency = 79/190 OR = to 41.57% which is in the ballpark of the article's quoted 40% for a supercharger. A Turbocharger can have an efficiency of up to around 75%. I also chose probably worst case conditions since Delta T is less at less RPM and Pressure. (I chose 10 PSI since that is what I started with in this discussion)

Since the object of installing a SC is to make more power by flowing more air it makes sense to pressurize the air first then cool it down using the IC.

Lets do one more calculation and look at what the actual air flow to the engine would be with and without an IC installed.

So far we know that producing 10 PSI of boost /1.68 pressure ratio on a 100 degree day and a 41.57% efficient SC the temperature gain in the air 190 degrees F for the Inlet Charge Temperature of 290 degrees F. All we have to do now is calculate the Density Ratio (DR)

Density Ratio (DR) = (SC Inlet Absolute Temp. / SC Outlet Absolute Temp.) X (SC Outlet Pressure Absolute
X SC Inlet Pressure Absolute) X (10PSIG + 14.7PSIA / 14.7PSIA ) OR

DR = (100 degrees F + 460 / 290 degrees F +460) X (24.7 / 14.7) OR

DR = (560/750) X (24.7/14.7) OR

DR = (.7466) X (1.6802) OR

DR = 1.254

So what does that stupid number mean? Basically it means in simplified form that the 1.68 pressure ratio OR the 68 % increase in airflow we gained when we pressurized the air with the SC to 10 PSIG is really ONLY 1.254 or about 25.4% actual improvement. This is due to the amount of density lost as a result of the SC actually pressurizing the air and causing its density to be reduced because of the heating effect.

From the density ratio equation we can see if we used an IC capable of reducing the charge termperature by say 100 degrees F we would restore the density ratio to 1.447 or we would gain almost 20% of what we lost from the IDEAL number of 1.68. This improvement can actually be calculated to be an 86% improvement over not using an IC at all.

This strategy is called Density Recovery and is the primary function the intercooler is designed to perform.

A second problem that arises from the SC heating effect takes us to the combustion chambers. Normal combustion of gasoline and air can be described as a somewhat predictable and controlled burn of the inlet charge that creates high-temperature gas pressure that moves the pistons down uniformly. Many engine varibles affect how well this happens and subsequently the torque of the engine.

Conversely, abnormal combustion (read detonation) can be described as the random and uncontrolled explosion of the inlet charge that creates high-temperature ultra-high gas pressure spikes that attempt to "hammer" the piston down. These pressure spikes, depending on when they occur and how they begin are known as spark knock, detonation, pre-ignition, post-ignition, rumble and run on. All of these terms have two things in common: they are adverse to engine duribility and power.

The temperature of the inlet charge at the beginning of the combustion process greatly affects whether the charge burns (normal) or explodes (abnormal combustion) and abnormal combustion lowers torque first and then breaks the engine.

The point being is that this explains why there is performance gains to be had from the intercooling process and also shows why low air charge temps move us away from the dreaded detonation or "knock" that kills HG's. It also shows that there are gains to be made if we can increase the ability of the IC to lower charge temperatures even further than that which occurs in the OEM IC."
 
Wantess-

I was thinking more something like this in the stock location and run both tubes over the top kinda like the MP FMIC setup:

stage1ic.jpg


I was thinking a 4.5x20x6 core (should fit ok, might need a little work). That would flow just about 1000cfm and provide better cooling. Probably still in a poor location for air flow though.

-Travis
 
TBone95

A number of IC things happeneing out there on SCs. Mansuir wants to use 2 on either side up front. Someone else is going with a truck IC. In the thread "Anyone know the correct operating temp"
http://www.sccoa.com/forums/showthread.php?s=&threadid=31215&perpage=15&pagenumber=2
Look at the post on page 2 by BKB. I like this other than the tubes routing and maybe a little twaeking of design. Anyway that red Mustang with an SC runs cold.

There is the inverted SC with water cooler underneath. There are other liquid types I read about here and seen at the track on Miata's. MP front mount and various double coolers available with fans. Lot to pick from now days. Maybe hit the search button on this.

I do like the idea of keeping your tubes on top.
 
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Yea I know theres plenty of IC ideas, Im just sharing mine. I kinda like the idea of a slightly less efficient IC that flows more air. Using Duffy's equation, reducing boost from 10psi to 6.5psi (the temp increase would be the same because 10psi is still being created, but only 6.5 actually reaching the cylinders) drops the DR down to 1.077 (not good). Even knocking 100* off the temp its still lower than the original DR (1.254) at 1.242.

Of course 10psi is fairly low for a SC, maybe Ill do some more calculations with higher pressure after Ive had some sleep.
 
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