AIT's - AIR TEMPERATURE TESTING

Discussion in 'SRT Hellcat Performance' started by Top Cat, Feb 12, 2016.

  1. Top Cat

    Top Cat Gold Member Hellcat Car Club Gold Supporting Member Fastest Cat/Record Holder HCC Charter Member

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    I thought this was an Interesting article to read.
    About the relationship between a supercharger, heat exchangers and intercoolers and how it affects to an engine.

    TC


    AIR TEMPERATURE TESTING

    At the end of the day, what really matters is HOW DOES MY SUPERCHARGER KIT

    PERFORM WHEN I’M IN BOOST? DOES IT DELIVER THE ADVERTISED HP AND

    PERFORMANCE? Occasionally, temperature or other test data by an individual may be

    misleading.

    For example: There has been considerable discussions regarding air and water temperatures of

    supercharger kits. Comparisons are okay if they are accurate. If not, they are just more

    misinformation circulating on the web.

    And, it is not our intent to compare the design and efficiency of any kit or the individual

    mechanical components that influence air discharge temp. These are the supercharger, inlet tract,

    intercooler, heat exchanger, pump etc. Optimizing these parts lower the air discharge temps.

    resulting in greater HP and reduced detonation potential. “Hot air” under-hood inlets increase

    temps and hurt performance by 30-55HP while adding an external real cool air kit does the

    opposite. One would have to be living in a village to not be aware of these basics- cooler air

    MAKES MORE HP.

    Instead, we hope to point out the testing procedure and criteria we use at Kenne Bell to

    accurately compare the charge and coolant temps when dyno testing. Disregard any of the

    following 12 parameters and accuracy is compromised resulting in bogus comparison data. As

    you will see, it’s easy to skew the data with even the same car, kit, day, ambient and boost.

    If any meaningful or accurate data is to be derived from comparing the air discharge temps of

    supercharger kits on a vehicle, it must be a controlled test with specific test parameters that

    ELIMINATE THE VARIABLES.

    All the below will, and do, affect temperature when tested on a chassis dyno. One “kit” may

    wrongly appear superior or inferior on the same vehicle because of the simple temp or boost

    reading error or failure to note a cool air kit upgrade or open vs closed hood change to one kit

    and not the other.

    Also, dyno testing with an open hood vs a vehicle at road speed are two different temp scenarios.

    VARIABLES THAT AFFECT COMPARISON TESTING

    1) UNDER-HOOD TEMP (HOOD UP VS DOWN)

    2) AMBIENT TEMP.

    3) ACTUAL BOOST (1 PSI OF BOOST= 10*-15* SC air discharge temps.)

    4) RPM, LENGTH OF RUN + GEAR RATIO

    5) STARTING AIR TEMP

    6) STARTING INTER COOLER FLUID TEMP.

    7) WATER VS. COOLANT RATIO

    8) SUPERCHARGER TEMP.

    9) INLET RESTRICTION

    10) IDLE-RUN-AFTER RUN

    11) WHERE THE ACTUAL CHARGE TEMP MEASUREMENT IS TAKEN

    12) IMPROPER CIRCULATION (AIR TO WATER)

    13) HEAT EXCHANGERS, INTERCOOLERS & PUMPS

    1a) FILTER TEMP- The ONLY measurement to use for “engine in” air temp. calculations. Other

    temp readings under, above or around the dyno or car are wrong. The engine draws air from the

    filter. Nowhere else matters. Keep in mind this temp. alters HP at 1% per 10* of variation. Also,

    cooler ambient air makes more boost.

    1b) UNDER-HOOD TEMPS (HOOD UP VS DOWN)- Why do dyno operators insist on testing

    with the hood “up?” That isn’t the way the cars are driven. CLOSE THE HOOD- unless you

    want false air data. Under-hood temps. reach 200* vs 70* or ambient outside air. If the filter

    (inlet source) is located under the hood, then the dyno run should be conducted the same wayhood

    closed. Why is that so difficult to grasp for so many? What are they afraid of? Yes, the hot

    under-hood air will reduce HP, increase the detonation threshold, lower boost, alter supercharger

    efficiency and elevate engine and exhaust temps. Not good, but it is what it is- hotter air.

    It’s why everyone uses scoops and not mini sized grill cracks to supply the 750-1500 cu.ft. of

    cool air flow required by the engine. And why the Camaro utilizes an air scoop in the grill. They

    are looking for cool outside air for their filter box. Close the hood with an “open” under-hood

    filter and watch your kits power drop 55HP! See “Kenne Bell 30HP Advantage” for

    comparisons.

    Fact: Very little cool air finds it’s way through those little 50 CFM grill openings. Yes, some

    outside air mixes with all that hot air from the radiator, engine, headers etc. but it is all ingested

    via the filter into your engine.

    Finally, under-hood shrouds and seals do virtually nothing. Once eliminated, this common but

    huge test misstep (we’ve seen up to 55 HP and 100* with hood “up” vs. “down”) the rest is

    common sense testing and the air and water data will support meaningful accurate results. All

    Kenne Bell kits mount the filter outside the engine bay where temps are cooler and consistent

    at any vehicle position or speed. The dyno fan will simulate vehicle high speed and under-hood

    air flow.

    So, no exceptions. Locate the ambient temp sensor at the filter whether it be under-hood (hood

    down) or behind the front bumper. Begin test at the same temp or data is junk.

    2) AMBIENT TEMP- Cool outside the engine bay air is what also cools the fluid in the heat

    exchanger. Cooler air= cooler water= cooler supercharger air into the intercooler= cooler air

    charge to engine= more boost= higher HP. So, ambient air temp should be the same as it

    influences all the other components. 20* higher ambient raises intercooler air and water temps. It

    does matter.

    3) ACTUAL BOOST- Boost makes HP, but it produces heat. There’s no free ride. Twin Screw

    positive displacement, and centrifugal superchargers generate approximately 10* of charge temp

    per PSI. Starting run design temps are approx. 10* per PSI + Inlet temp. Example: 90* ambient +

    90* (9 PSI) = min air charge temp 180* before intercooler. Roots style are higher. Be sure

    “actual” boost is the same. Don’t just assume all 9 PSI kits develop exactly the same boost. The

    intercooler system (air to water or air to air) is typically 50-75% efficient depending on numerous

    kit design variables. To accurately compare kits, boost cannot vary.

    4) RPM, LENGTH OF RUN & GEAR RATIO- The higher the RPM, read end or trans. gears the

    longer the dyno run and the greater the final temp. Everything heats up with time until there is

    stabilization. Use the same vehicle to insure accuracy.

    5) STARTING INTERCOOLER WATER TEMP- If the intercooler water ( it cools the air) is

    20* hotter at the “start” of the run, the “finish” will be hotter. Start temps must be identical for

    accurate comparisons. Intercooler “start” water and air temps can vary from ambient 70* to 200*

    depending on idle time. Now, at what temp do you “start” the run? Get the picture?

    6) STARTING INLET AIR TEMP- Same here. Obviously, a hotter filter at the beginning of a

    run results in higher supercharger discharge temps. A 30-50* variance is common. Start test at

    same filter air temp. or the tests are useless. NOTE: Under-hood filters are difficult to test

    because engine bay temps increase (heat soak) with time when idling from ambient to 200*.

    Open the hood and let cooler dyno room external air blow in and the test are skewed.

    7) WATER VS. COOLANT- Since no liquid cools better than water, 100% water is best. 50/50

    is not as efficient in cooling. 90/10 is better. Try placing ice cubes in a pot of coolant. Ice 32*

    and coolant 50* between the ice cubes. Engine coolant “resists” lower temperatures and freezing.

    Run the same mix when testing if your goal is an accurate comparison.

    8) SUPERCHARGER TEMP (HEAT SOAKING)- Obviously, heat soaked components can heat

    the air passing through them. For example: We use a thermal laser gun to quickly measure

    supercharger case temp. If the supercharger is covered (never on our design priority list) with a

    manifold, intercooler or plastic engine cover, it obviously runs hotter. Then there’s the heat

    transfer from the engine. However, for test comparisons, the temps. of the supercharger and other

    metal or plastic pieces in a particular kit “are what they are.” Also consider the type of

    supercharger and the pressure ratio. Centrifugals run cooler at idle because they are not

    compressing air (boost) like the positive displacement superchargers. No heat of compression- no

    boost. Less boost at low and mid range- less heat. Boost IS heat. The twin screw can run higher

    pressure ratios of 2.1 (15 psi) vs 1.4 (6 psi) so, of course the “idle” temps are higher. Again, you

    look at the higher efficiency and boost of a 15-30 psi Twin Screw and the benefits. Higher IAT’s

    are unavoidable.

    9) INLET RESTRICTION- NEVER compare 2 kits with inlet tracts ( filter, meter, tubing,

    throttle body etc.) that vary in restriction/efficiency. If one inlet is larger and enjoys less

    restriction to air flow to the supercharger, then the supercharger is not required to work as hard.

    Like sucking coke through a straw vs. a straw half pinched off. The upside of a larger inlet tract

    is the supercharger uses less HP to suck in the air and subsequently runs cooler AND develops

    more boost. Supercharging efficiency, boost and inlet temps will all be better but DIFFERENT.

    10) IDLE/RUN-AFTER RUN- Idle temp. will be highest before a run. Let it cool to the test

    temp. and make the run in the same gear, car, boost, trans. and RPM. Check the data at the same

    peak RPM as everything heats up after getting off the throttle.

    11) WHERE THE ACTUAL CHARGE TEMP MEASUREMENTS IS TAKEN- This is

    probably the most important part of the measurement process. Equally important is the sensor

    being used is properly calibrated. Different air temp sensors can be calibrated differently and if

    the person testing is not aware of this, all data will be useless. Transfer functions are different for

    some push in type sensors vs screw in type and vs shielded/unshielded sensors. The most

    accurate and fastest response air temperature sensors are the unshielded type. Never compare

    shielded sensors against unshielded.

    Given that the a) sensor types are the same (unshielded) and b) the transfer functions are correct,

    then c) placement of the sensor is critical. Let’s make sure we are not using a sensor that is

    located upstream of the supercharger on one system and then downstream on the other. Believe it

    or not this mistake has been made before. Whenever temperature readings are only a

    few degrees above ambient under boost, always suspect the sensor is either a)

    located upstream (before) the supercharger as is the case in many applications

    if a new sensor has not been relocated from the factory location to the discharge

    side of the intercooler, or b) sensor is incorrectly calibrated or c) sensor is of the

    shielded type. Ever wonder why there are sensor “relocation kits?” was it the wrong location?

    Big problem when the Camaro and other Ford kits were introduced.

    12) IMPROPER CIRCULATION (AIR TO WATER)- Always compare systems that have proper

    water circulation. A common error when seeing high discharge air temps is not to insure there is

    adequate flow in the system. In any new installation it is very easy to have air pockets that

    hinder/stop circulation of the liquid (cooling media). Even the best designed system can produce

    high charge temperatures if proper purging of the intercooler system has not been performed.

    Blockage of airflow to the heat exchanger from debris, bumper cover, etc. can also have a drastic

    effect. There has to be sufficient airflow across the heat exchanger to drop the charge

    temperature.

    13) HEAT EXCHANGERS, INTERCOOLERS & PUMPS- At Kenne Bell we test numerous

    configurations and sizes, including our competitions heat exchangers, intercoolers and pumps.

    HEAT EXCHANGERS

    We double or stack heat exchangers and check various frontal locations for air flow velocity (in

    and out), cooling and heat soaking.

    Example: A larger surface area HE mounted in front of a radiator may seem like a great idea but

    it has distinct shortcomings.

    1) RESTRICTION- Who can deny that it is a big restriction to the radiators air flow and

    ENGINE COOLING. The engine WILL run HOTTER!

    2) TEMP- Do you really believe 70* ambient blowing through a 130* of HE water will

    cool a radiator better than the 70* air? Oops!

    INTERCOOLERS

    Thinner intercoolers flow more air and enjoy less boost loss because the core is less resistant to

    laminar air flow. Thicker cores flow less air, kill more boost but do a better job of cooling.

    HOWEVER, THE LOWER BOOST WILL REDUCE HP by 15-20 HP/ psi loss. Yes, the

    supercharger boost and speed can be increased.

    PUMPS

    Unfortunately, the supercharger will now consume more engine HP to blow the additional

    through the thicker more restrictive core. Excess water flow/ speed through the HE doesn’t allow

    sufficient time for the water to remain in the core and cool. Insufficient flow/speed keeps the

    water in the HE too long resulting in excess heating.

    CONCLUSION

    When we develop this package, temps and flow (air and water) are measured both “in” and “out”

    of the HE, IC, radiator and pumps in addition to the all important filter temp.

    That’s how Kenne Bell develops and tests product. Again, it’s all about the overall design at

    WOT and the HP the supercharger kit produces in boost. No one can deny they make plenty of

    HP with room to grow.

    What we often think is the same is the same but it’s different.

    If analyzing supercharger kits by the same or competing manufacturers, it is important to refer to

    the above 13 test variables and make the necessary adjustments to guarantee boost temperatures,

    run length, inlet, restriction, temps measurement location is identical- and the hood is CLOSED,

    like you drive the car .

    There’s a saying on the Kenne Bell dyno that an OEM engineer left us- “One of the real dangers

    in running a test is you are bound to get data”.

    We hope the information is helpful.
     
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  2. Top Cat

    Top Cat Gold Member Hellcat Car Club Gold Supporting Member Fastest Cat/Record Holder HCC Charter Member

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    Sorry about the long read, but it has some good information on CAI, location of filters, what is ambient air temps and what effects them, some times you need to look farther than just a sales pitch and start asking questions, if they don't get answered then maybe that should be a red flag, fixing a problem with a fix to fix the first issue usually means you paid for something that did not do what it was sold to do.....................
    TC
     
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  3. Top Cat

    Top Cat Gold Member Hellcat Car Club Gold Supporting Member Fastest Cat/Record Holder HCC Charter Member

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    I've had conversations with CR racing and they said contrary to belief a thinner core will cool better than a thicker one, there are a lot of different factors when designing a unit,location, size of the unit,fluid flow rate,how much surface area and how much of the radiator is being blocked as that will increase engine temps, so it's a balance of things when doing a daily driver vs a pure race car, also the use of fans will greatly increase efficiency of the unit.
    TC
     
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  4. Top Cat

    Top Cat Gold Member Hellcat Car Club Gold Supporting Member Fastest Cat/Record Holder HCC Charter Member

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    Physics 101? One of a few reasons both AFCO and CR Racing recommend the fan version for better cooling in the street cars .
    TC
     
  5. TallCool1

    TallCool1 Gold Member Hellcat Car Club Gold Supporting Member Nat'l Hellcat Tech Advisor HCC Charter Member

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    It was just a reference that shorter intercooler fins usually present more streamlined air flow / less air path oposition.

    As a description of movement in physics, laminar (of a flow) is taking place along constant streamlines; not turbulent.

    Bell used it correct in context.
     
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  6. 8SECSRT

    8SECSRT Hellcat Member

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    Thicker intercoolers/HE have a few plus and minuses. Fin count is a no brainier but we don't have the room for massive HE up front unless we cut the front cover.
     
  7. Racist Cat

    Racist Cat Silver Member

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    I took it to man, internal air flow?
     
  8. Top Cat

    Top Cat Gold Member Hellcat Car Club Gold Supporting Member Fastest Cat/Record Holder HCC Charter Member

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    The thinner unit with twin fans would fit and cool better for street driven cars, the AFCO unit with fans fit just need them to turn the top inlet tube, CR will do one also if anyone is interested.
    TC
     
  9. White Trash

    White Trash BMF Hellcat Car Club HCC Charter Member HCC National Vice Pres.

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    On a race run application the colder the air going into the engine the more HP it makes.
    I have ice tanks pumping ice water into the supercharger cooling the charge. On my Outlaw Car although it's a Turbo it's a makes a difference of 150 HP. The air is 40 degrees off the trans brake and 45 degrees at the end of a run
     
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  10. Racist Cat

    Racist Cat Silver Member

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    On my diesel, we would use co2 to cool down hard parts. Just like nos, same bottles, solenoids, etc.

    An idea. Could spray below the supercharger, or the top cover. Even could spray into the center hood vent, and make it look like purging nos, lol.

    Also, we used to use water injection and nitrous together.
    The engine really didn't care for ice in the intake, so, you have to be careful, but, water injection on a super charged car is where it's at.
     
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  11. TrackDay

    TrackDay Silver Member

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    I'm not sure what you mean by AFCO and CR. Are you talking about a different LT radiator or . . . ? The only one I've heard of is the BWoody.
     
  12. Top Cat

    Top Cat Gold Member Hellcat Car Club Gold Supporting Member Fastest Cat/Record Holder HCC Charter Member

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    AFCO and CR Racing make heat ex changers and radiators , I have used the AFCO on Linda's 2010 challenger race car when we had the 4.2 Kenne Bell super charger on it, CR Racing was very interested in making a unit for the Hellcats.
    TC
     
  13. TallCool1

    TallCool1 Gold Member Hellcat Car Club Gold Supporting Member Nat'l Hellcat Tech Advisor HCC Charter Member

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    CR Racing is top notch. I'd love to see someone offer their car as a test mule. They have have a great facility in Indy you can find them here Home - C&R Racing

    When I spoke to them they wanted to do a complete setup engine and sc coolers. They really need a car otherwise all parts including mounts everything cooling related behind the facia, which is what stopped me. That said anyone who works with them will likely get a hell of a deal, they deliver the best and it would open up something for the Hellcat community.
     
  14. Top Cat

    Top Cat Gold Member Hellcat Car Club Gold Supporting Member Fastest Cat/Record Holder HCC Charter Member

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    Paul seems like a great guy to work with at CR, I agree someone in the Indiana area should step up, if need be I can get them in contact with Paul.
    TC
     
  15. TrackDay

    TrackDay Silver Member

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    I can be in Indy in about 3 hours. If he's interested I'll give feedback on how well a LTR cooler does in 20 minute track sessions. Just need to know what he'd like to do to the car and how long he needs it.
     

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