IAT2 Seem High with two HX's

[Robinjo]

I installed my secondary heat exchanger (HX) and I'm not wild about the numbers I'm getting. I'm seeing about a 35-40 degree F difference between the IAT1 and IAT2, with intake being about 60-65 degrees F and IAT2 at 90-95 degrees F. I am measuring IAT2 with the Torque app via a OBD-2 dongle. I ensured that I am getting flow through the system ands that there is no kinks in the hoses. My setup has the dual pass installed and am still running the stock DF HX. I do have the stock fan on the front HX but do not have one on the rear mounted unit.

Are these numbers ok and I'm worried about nothing?

I have two other possibilities that I need to look into, but am open to other items or suggestions to look into.
1. The input in the Torque app is off.
2. The Laminova cores are dirty and need cleaning (not looking forward to this since they are fragile).

Insert photo of setup.

Routing.

 

[ncgoblin]

Those seem like excellent numbers what is the ambient temperature outdoors?

 

[Robinjo]

55-60 degrees F. I was just concerned because some other members have talked about their IAT2 being right on with IAT1 with two HX units.

 

[ncgoblin]

55-60 degrees F. I was just concerned because some other members have talked about their IAT2 being right on with IAT1 with two HX units.

There is more friction the closer you get to IAT2 sensor before entering the cylinder I would expect IAT2 to be higher regardless. 90-95F is of no concern for IAT2 but I would be curious what the reading will be when the ambient is closer to 90F outdoors. For example my supercharger with an overhead heat exchanger was reading 140F with an ambient of 90F. Anything over 150F I would be concern about possible KR which I personally never experienced logging HP tuners.

 

[Robinjo]

I would be curious what the reading will be when the ambient is closer to 90F outdoors.

That is ulimately what I'm worried about as well. If I'm +35 now with cooler air, what is my IAT2 going to be when it's 100 F in the summer. I've never had it go over 135 degrees with the single HX so I was hoping it would be lower with two units.

 

[Gtstorey]

Where did you locate the second heat exchanger, and how big? With the the temperature differences that we are talking about, a heat exchanger without a lot of airflow over it won't do much. Without airflow, all you do is add volume to the system.

 

[Rauq]

If you can get the laminova cores out, cleaning them is not that hard. Just hit them with a can of brake clean. Make sure they're oriented correctly for the dual pass.

Short of clean laminova cores, the only other thing you can do to work towards cooler IATs is a phenolic spacer. The block puts heat into the supercharger housing and the intake manifold (and theoretically into the intercooler loop too).

There may not be much gains to be had with significantly more HX capacity than intercooler capacity. The first HX will achieve a significant temp drop because the fluid coming into it is significantly warmer than the air flowing across it. Once it's almost as cool as it can get, ambient temp air isn't going to cool it much more. There's just not enough ∆T to make a difference.

Even if you had a hypothetically unlimited supply of ambient temp water, the laminova cores can only pull so much heat out of the charge air. That's the other part of why additional HX capacity only does so much for you.

 

[Robinjo]

Where did you locate the second heat exchanger, and how big? With the the temperature differences that we are talking about, a heat exchanger without a lot of airflow over it won't do much. Without airflow, all you do is add volume to the system.

On the rails behind the seats. Up as high as I could get it mounted as to get the most air and least heat from the engine. I'll snap photos later, it looks like this one below. It's a ZZP looking front mount HX, so not massive but bigger than the stock unit. It is an experiment, so if I don't see a great gain from the unit I can go back to the single HX unit.

Short of clean laminova cores, the only other thing you can do to work towards cooler IATs is a phenolic spacer. The block puts heat into the supercharger housing and the intake manifold (and theoretically into the intercooler loop too).

There may not be much gains to be had with significantly more HX capacity than intercooler capacity. The first HX will achieve a significant temp drop because the fluid coming into it is significantly warmer than the air flowing across it. Once it's almost as cool as it can get, ambient temp air isn't going to cool it much more. There's just not enough ∆T to make a difference.

Even if you had a hypothetically unlimited supply of ambient temp water, the laminova cores can only pull so much heat out of the charge air. That's the other part of why additional HX capacity only does so much for you.

Thanks for the description. I wasn't thinking of it that way, that the first HX is doing the bulk of the 'work'.
I do have the phenolic spacer already as well, I forgot to add that in my list of mods. I am planning to take my SC off to change the fluid and coupler this winter. If I'm that far in I'll try to pull the cores to see what they look like. I'm just a bit nervous as they like to scar easily and they are impossible to find now.

 

[Rauq]

You did pull them to swap around for the dual pass, right?

 

[Robinjo]

I didn't. My donor came with a GM Stage 2 kit on it that already included the dual pass installed. I didn't pull it off to check it all out because I don't want to mess any of it up.

 

[Joebob]

My before and after pulled from the donor. That being said, your temps seem fine.

 

[Rauq]

Yes, I should have started with, your temps don't seem that bad.

If you can get the intake manifold out of the car, removing the laminova cores isn't that hard. I am a big fan of the hose clamp method, but as long as you're careful and intentional about it, you should be able to pull them without issue. Mine went from about that dirty to about that clean as well.