IAT2 ranges 40-50* above ambient with HE/fans

[Catmonkey]

When does it pull timing? 140* and up is what I was told.

It's a programmed parameter and tends to be progressive. The hotter it gets the more timing is pulled. This is a tuneable parameter. Stock tunes start pulling timing as low as 100*. I think most tuners start pulling timing at around 125*, but I'm sure it varies. By 140*, I'm sure you could see something like a degree to 1.5 degrees of timing pulled.

 

[Bad Company]

I'm going to ask a few real important questions.

Is the SC a positive displacement air pump?

If it is a positive displacement air pump, what happens to the air it is displacing/moving while the engine is idling?

Yes, I realize that the efficiency range of the SC is low while the engine is at idle.

Do you think the volume of air the positive displacement pump is moving is less than or greater than the engines requirements to maintain a stable idle while sitting at a traffic light?

If you think the SC throughput in CFM is higher than the requirements of the engine's needs for air in CFM to idle.........what is happening to the excessive volume of air the SC is moving?

If the SC is not moving air across the rotors while it is turning with the engine at idle.......are you starving the SC of needed air to cool the rotors of the SC?





The bypass valve opens to allow the excessive air by volume that the SC is pumping to be returned to the inlet of the SC.




The bypass valve doesn't bypass the air from the inlet elbow of the SC to the lower half of the intake manifold for the engine to burn. To do this is to completely starve the SC of air. The SC is nothing more than an air pump. It moves air all the time....... regardless of whether or not it is in the efficient RPM range of its pressure/flow maps.

If the SC moves air all the time.........where does the air from the SC go, if the bypass valve/system only allows air to flow from the inlet area behind the throttle body of the SC to the lower half of the intake manifold while the engine is idling?

Where does the excessive air output of the SC go when the engine isn't using it to make Hp?


What happens when you get in the throttle and go into full boost and bring engine RPM up to 6000 RPM with SC RPM of 18,000 and you take your foot off of the throttle? Under this scenario the SC is very much in its efficient part of the map. How does it move air now? Does it stop moving air? Or does the bypass system allow the excess air to bleed back to the inlet of the SC to be recirculated while the engine is being starved for air under this condition due to the fact the throttle blade is closed?

The pump(supercharger) always wants to pump.

 

[fishpick]

I'm going to ask a few real important questions.

Is the SC a positive displacement air pump?

If it is a positive displacement air pump, what happens to the air it is displacing/moving while the engine is idling?

Yes, I realize that the efficiency range of the SC is low while the engine is at idle.

Do you think the volume of air the positive displacement pump is moving is less than or greater than the engines requirements to maintain a stable idle while sitting at a traffic light?

If you think the SC throughput in CFM is higher than the requirements of the engine's needs for air in CFM to idle.........what is happening to the excessive volume of air the SC is moving?

If the SC is not moving air across the rotors while it is turning with the engine at idle.......are you starving the SC of needed air to cool the rotors of the SC?





The bypass valve opens to allow the excessive air by volume that the SC is pumping to be returned to the inlet of the SC.




The bypass valve doesn't bypass the air from the inlet elbow of the SC to the lower half of the intake manifold for the engine to burn. To do this is to completely starve the SC of air. The SC is nothing more than an air pump. It moves air all the time....... regardless of whether or not it is in the efficient RPM range of its pressure/flow maps.

If the SC moves air all the time.........where does the air from the SC go, if the bypass valve/system only allows air to flow from the inlet area behind the throttle body of the SC to the lower half of the intake manifold while the engine is idling?

Where does the excessive air output of the SC go when the engine isn't using it to make Hp?


What happens when you get in the throttle and go into full boost and bring engine RPM up to 6000 RPM with SC RPM of 18,000 and you take your foot off of the throttle? Under this scenario the SC is very much in its efficient part of the map. How does it move air now? Does it stop moving air? Or does the bypass system allow the excess air to bleed back to the inlet of the SC to be recirculated while the engine is being starved for air under this condition due to the fact the throttle blade is closed?

The pump(supercharger) always wants to pump.

I think folks "get" how a PD blower works, you have been very clear a couple of times now...
The data folks (including myself) are seeing in terms of IAT2s does not reconcile with the notion of non-compressed, partial vacuum air (not making its own heat) being recirculated over an intercooler multiple times... Logically, that should be "cooler" IAT2s not hotter... I think that's the crux of what people are discussing / asking about.
I know that's my bit of irreconcilable logic!

 

[Bad Company]

I think folks "get" how a PD blower works, you have been very clear a couple of times now...
The data folks (including myself) are seeing in terms of IAT2s does not reconcile with the notion of non-compressed, partial vacuum air (not making its own heat) being recirculated over an intercooler multiple times... Logically, that should be "cooler" IAT2s not hotter... I think that's the crux of what people are discussing / asking about.
I know that's my bit of irreconcilable logic!

Yes I know what the OP question was about. My comprehension of the reading of following posts is that a number of people believe that once the bypass valve is open that the air never passes through the intercooler. That it passes from the SC inlet elbow to the bypass system and the lower intake without passing through the intercooler. Hence the belief of high IAT2 readings.

I was trying to clear that misconception up.

Now why are the IAT2 readings high? Well that could be caused by many issues. Has the tune been altered to bring the intercooler pump on earlier or not? Does the car have the cast iron exhaust manifolds or headers? Why would that matter? The cast iron manifold will act as a heat sink to raise under hood temperatures when the car isn't moving. Does the car have a 170*F thermostat? The engine block, heads, supercharger and intake manifold are all heat sinks that will radiate heat back to the inlet air stream of the idling engine, along with radiating heat under the under the hood of the engine bay area. Does the car have the older style intercooler pump that has a 50% lower water flow rate of the 13/14 cars? A lower water flow rate pump doesn't transfer the same amount of heat in the form of BTUs from the intercooler to the HE.

I'm sorry if my trying to explain how the bypass valve works upset you, but my comprehension of what I was reading was that people believe that the air enters from under the hood at the air filter and travels straight to the lower half of the intake manifold without ever passing through the intercooler and that THIS was WHY the IAT2 temps where so high driving at low load engine conditions or sitting in traffic.

I'll leave you to your discussion without any further input to upset you

 

[jdt1970]

Yes I know what the OP question was about. My comprehension of the reading of following posts is that a number of people believe that once the bypass valve is open that the air never passes through the intercooler. That it passes from the SC inlet elbow to the bypass system and the lower intake without passing through the intercooler. Hence the belief of high IAT2 readings.

I was trying to clear that misconception up.

Now why are the IAT2 readings high? Well that could be caused by many issues. Has the tune been altered to bring the intercooler pump on earlier or not? Does the car have the cast iron exhaust manifolds or headers? Why would that matter? The cast iron manifold will act as a heat sink to raise under hood temperatures when the car isn't moving. Does the car have a 170*F thermostat? The engine block, heads, supercharger and intake manifold are all heat sinks that will radiate heat back to the inlet air stream of the idling engine, along with radiating heat under the under the hood of the engine bay area. Does the car have the older style intercooler pump that has a 50% lower water flow rate of the 13/14 cars? A lower water flow rate pump doesn't transfer the same amount of heat in the form of BTUs from the intercooler to the HE.

I'm sorry if my trying to explain how the bypass valve works upset you, but my comprehension of what I was reading was that people believe that the air enters from under the hood at the air filter and travels straight to the lower half of the intake manifold without ever passing through the intercooler and that THIS was WHY the IAT2 temps where so high driving at low load engine conditions or sitting in traffic.

I'll leave you to your discussion without any further input to upset you

Speaking for myself only, I never thought that the sc itself got bypassed. I am in the catmonkey school of thought. Temps should be cooler under bypass for all the reasons you stated but they are not. I tend to agree with the heat sink theory. I am getting header in a month or two so I will let you know if temps drop.

 

[fishpick]

@Bad Company - it's takes a lot more than that to upset me (that's the problem with black and white iterwebs boards - I'm not upset at all)...

As for the IAT2 temps - this is where everyones setup changes things... like @jdt1970 - I can only speak for myself... My setup the IC pump runs WOT all the time... yes I have heat sink issues with stock manifolds - but I STILL don't "get" why if the SC is circulating that hot air over the IC again and again on bypass, why are the temps are so high... until BOOST - which "makes heat" - and then they drop like a rock...

Also - for grins the other day I put a temp probe in the IC fluid stream and "just drove around town" - no boost... IAT2 temp went up - coolant moved up ever so slowly... as in - totally not heat soak where the coolant was at 130 and unable to cool the air. Th coolant went up so little - I find it hard to believe it was the IC putting heat into the coolant as it could easily have been just ambient from the hoses... I dunno...

Now that my damn blower is eating belts - IAT2 temps are the least of my concerns

 

[HillbillyHotRod]

If the blower is eating belts, are the pulleys aligned?

 

[fishpick]

If the blower is eating belts, are the pulleys aligned?

I think so... Was right after the install of the replacement "more better" Whipple tensioner to stop the belt from slipping...

I'm about ready to pull the blower, sell the damn thing, and put on a turbo...

 

[V8Flexin]

I believe at low rpm the supercharger is not producing enough air flow to feed the engine at idle necessitating the need for air to bypass the supercharger, meaning warmer non cooled air being feed to the lower intake thus the warmer temperatures. One way to test this theory is to close the bypass while at idle and see if rpm rises or drops. If it drops then the blower is the restriction, if it rises then its producing too much flow.

Sent from my PURE XL using the svtperformance.com mobile app

 

[Catmonkey]

It would be interesting to see if changes engine vacuum and by how much.

 

[Bad Company]

The simple way to know what the SC is moving in air by volume is to use a little math

Lets say the engine has a Eaton 2.3L SC on it with stock pulleys.

Damper pulley diameter is 7.5"

Upper pulley diameter is 2.71"

7.5 divided by 2.71 = 2.7675 drive ratio

The engine idles at 700 RPM

700 engine RPM x 2.7675 pulley drive ratio = 1937.2693 SC RPM

1937.2693 SC RPM x 2.3 Liter of air per revolution = 4455.7193LPM of airflow.

4455.7193LPM is divided by 28.316847 to convert LPM to CFM, which = 157.35223CFM

157.35223 CFM of air is what the rotors of the SC are trying to move while the engine is idling.

The next question would be how much air by volume is required by the engine to maintain the 700 RPM idle with no load?

Want to bet that it is less than 157 CFM?

In fact I'd say it only takes 60-70 CFM to maintain the idle speed of 700 RPM

 

[50stangpower]

When I look on my sct x4 I only see one iat sensor. Is that iat2? I want to make sure I'm comparing the same thing.

 

[V8Flexin]

When I look on my sct x4 I only see one iat sensor. Is that iat2? I want to make sure I'm comparing the same thing.

So far I've only been able to monitor iat2 in voltage only after trying to configure a custom datalog file with my x4. I spent so much time going through all the available selections that I gave up.

Sent from my PURE XL using the svtperformance.com mobile app

 

[Bad Company]

Heck, lets even compensate for the SC turning under the map and only working at 60% efficiency

157.35223 CFm x 0.60 = 94.411338 CFM the SC wants to move in volume of air.

here is a link to find the volume of air required in CFM

http://www.widman.biz/English/Calculators/CFM.html

If I plug in 700 RPM for a 354 CI engine with a volumetric efficiency of 65% the calculator comes up with the required CFM of 47CFM.

94.411338 CFM - 47 CFM a difference of 47.411338 CFM........meaning the SC wants to move roughly 50% more air by volume than the engine requires to maintain an idle of 700 RPM.

Now why did I use a 65% volumetric efficiency for the engine? For the same reason I used 60% for the SC. At low RPM neither the engine or SC are operating at the maximum efficiency levels they are designed for. I honestly believe the engine at 65% volumetric efficiency is high, since i doubt these engine are much higher than 82 or 83% at optimum operating RPM in stock form.

 

[Bad Company]

@Bad Company - it's takes a lot more than that to upset me (that's the problem with black and white iterwebs boards - I'm not upset at all)...

As for the IAT2 temps - this is where everyones setup changes things... like @jdt1970 - I can only speak for myself... My setup the IC pump runs WOT all the time... yes I have heat sink issues with stock manifolds - but I STILL don't "get" why if the SC is circulating that hot air over the IC again and again on bypass, why are the temps are so high... until BOOST - which "makes heat" - and then they drop like a rock...

Also - for grins the other day I put a temp probe in the IC fluid stream and "just drove around town" - no boost... IAT2 temp went up - coolant moved up ever so slowly... as in - totally not heat soak where the coolant was at 130 and unable to cool the air. Th coolant went up so little - I find it hard to believe it was the IC putting heat into the coolant as it could easily have been just ambient from the hoses... I dunno...

Now that my damn blower is eating belts - IAT2 temps are the least of my concerns

You answered your own question if you think about that one.

 

[Catmonkey]

Heck, lets even compensate for the SC turning under the map and only working at 60% efficiency

Now why did I use a 65% volumetric efficiency for the engine? For the same reason I used 60% for the SC. At low RPM neither the engine or SC are operating at the maximum efficiency levels they are designed for. I honestly believe the engine at 65% volumetric efficiency is high, since i doubt these engine are much higher than 82 or 83% at optimum operating RPM in stock form.

We're talking ilde to 1,500 rpm, at least I have been. 60% is very generous at these speeds when Eaton's own performance map on the 2.3 shows 70% as its highest isentropic efficiency. But I get your point. You may have more air flow coming up through the by pass than actually going down into it. Low airflow over the rotors may have more to do with the higher IAT2s at these low engine speeds than I was considering.

 

[Bad Company]

We're talking ilde to 1,500 rpm, at least I have been. 60% is very generous at these speeds when Eaton's own performance map on the 2.3 shows 70% as its highest isentropic efficiency. But I get your point. You may have more air flow coming up through the by pass than actually going down into it. Low airflow over the rotors may have more to do with the higher IAT2s at these low engine speeds than I was considering.

Catmonkey the SC would have to be at 30% efficiency to be equal to the engines demands.

157.35223 x .30 = 47.205669 CFM

At this level you then have other issues with the airflow. Which of the two is going to demand the air and how is that going to disrupt airflow at the inlet elbow where the bypass valve and the opening to the SC rotors are located. If the SC was demanding 47 CFM and the engine was demanding 47 CFM..........what is going to happen to the air stream as two forces act upon it in equal terms in opposing directions?

 

[Bad Company]

Now the next thought is what happens when you install an OD Damper pulley with a smaller upper pulley?

What happens when you install a more efficient Screw supercharger that is larger in size to the stock supercharger?

 

[50stangpower]

So far I've only been able to monitor iat2 in voltage only after trying to configure a custom datalog file with my x4. I spent so much time going through all the available selections that I gave up.

Sent from my PURE XL using the svtperformance.com mobile app

So I assume the iat that's on the display is pre heat exchanger?

 

[Catmonkey]

There are two air temperature sensors. One is in the MAF, the other is the sensor sticking out of the intake manifold on the driver's side. If it doesn't say IAT2, it's likely IAT at the MAF. Most naturally aspirated engines don't have a second sensor.

Anyone attempting to monitor IAT2 with an AeroForce gauge in a 2011+ and can't find it, you need to send your gauge in for an update that has the parameter. If you're trying to log it and can't find it or it's not displaying in degrees, try downloading a newer version of Live Link and updating your flash tool.