What could be causing high IAT temps???

I have aproximately a 6 Gallon Tank in the trunk for intercooler coolant and eit hthe lines and Heat Exchanger it probably holds about 7.5 gallons if i had to estimate it



The Pump is a Meziere Remote Intercooler Pump, which has a 20 GPM flow rate



Theway the lines are set up is the fluid leaves the tank and enters the Intercooler, exits the intercooler into the Heat exchanger, then back to the tank. This was done to make sure that when i add ice to the tank, tthe coldest fluid reaches the Intercooler first for best performance. I realize thiswill increase temps for normal street driving but does not explain the near 80-90 degree shifts in temperature that i describe below.

I have been doing some testing lately and on pretty cool nights, High 50's to low 60s, my IAT temps are ranging from 118 to 198. This is all at a 75mph cruise speed on Cruise Control at about 2500rpm. In a period of 5 minutes the temps will slowly increase and get as high as 198 degrees. Then in a period of about 30 seconds, the IAT temps will come all the way down to 130 or so, and continue to fall for another minute or so. Then the process repeats itself

I have checked the pump to make sure it is pumpig fluid and it is. The fluid is definately getting hot, much warmer than 100 degrees but i do not have an exact temp. I do know the fluid in my Stock KB tank never reached over 100 degrees before. I have pulled over many times during the rise in temps to check that the pump is still pumping and it is each time. The only thing I can think of is that the pump might be stopping and starting somehow during the course of driving but everytime i check it it is pumping

TRhe last time i was at the track it wasnot pumping fluid and i had to bleed the pump to restart it but sicne then it has been running well. Any ideas, thoughts, or suggestions?

what type of sender/gauge you're using to measure IAT? or do you check it thru ODB? I don't remember how PCM (ODB) measures IAT...

other or you could run a led that shows when the pump is running (or not running).

Damn... almost sounds like there is a thermostat in the system somewhere. I know there probably isn't, but that is what it sounds like.

Is the pump always on, or is it possibly thermostatically controlled?

as far as i kno it is always on, no thermostat in the system. I am measuring through OBD2, same as i did with the KB tank last year with the stock motor

What kind of coolant are you using? ratio to water? 20 gpm is not very high, my fish tank filter pump moves 1200 gph (about 20 gpm). I would think that the flow rate is not high enough.

I have zero experiance with heat exchangers...just trying to put some ideas out there to help.

IAT

Is there a way to check return flow? I mean are you pumping against a dead head? Seems like a big burp is needed or you have some blockage, or may not enough flow (too much intercooler/HE volume for the pump and you are keeping a constant air bubble at the high point?? Just speculating. I hope you figure it out!

Just to confuse the issue some more - you could have too little or too much flow - either could cause what you are seeing. Too little and heat exchange process saturates and heat builds up on the "hot side" of the system. Too much flow and the exchange is erratic and incomplete - so heat builds up on the hot side of the system...

One more thing to look at - when I hear bouncing temperatures, I am reminded of my wifes rear-engine car that did that - the end result was a hose ballooning somewhere between the rear of the car and the radiator up front... The balloon was well hidden and not very impressive, but over a long enough stretch of hose that it held about 1/2 the capacity of the overflow tank...

That could be aggravated by whatever you are using to bleed off pressure when it heats up - which is what exactly?

^^^Yep

I just had a meeting today about this...

First of all, I'm not quite sure about the flow rate. I do know you should call whipple and ask them what there pump flows and believe it or not, you do not want to be over.

In a nutshell, here is what I learned today from Jim at KB, Dustin at Whipple, and they guys building my car...

With the IC resevoir in the trunk, you want to make sure the pump is in the rear with the resevoir and you want it to be 'pushing' to the front. Whipple explained the the lightning guys have been doing large trunk mount resevoirs for a few years and this is what they learned through trial and error. For some reason the pumps work best 'pushing' to the front, rather than 'sucking' from the back.

#2 - I found interesting is that if the pump flows too much, it is actually counterproductive. They gave me a whole shpeil about the science of pressure, flow, etc. I forgot that part but I remember it was not good..lol

I ended up taking off my MSD pump, and putting on a whipple pump. I can check the flow rate for you on Friday when I'm back if you need it.

The last thing that was interesting was the fact to make sure your resevoir has a breather. Don't just use the cap breather as the breather. Also, you probably did this but just to cover the basics, we put a steel cylinder drilled out with tiny holes in the corner of the resevoir and ran the pump under that. This is to ensure no ice blocks the feed ever. This also controls the flow. We ran a garden hose in the inside at full flow and it reached the pump at the same pace. Now you haven't been running ice, but thought I'd mention that anyway.

Make sure your pump is 'pushing' to the front from the back and not 'sucking' from the back to the front, and make sure you're pump flow is correct for your set-up.

BTW: mine holds 11 gallons of water but I will be running about 6 gallons on the street. I'll only use the extra space for ice at the track.

Good luck and keep us posted.

In addition to what CK said, I was about to post a PS of:

a. sounds more and more like a pressure/cavitation issue when I think about it
- see CK's comments about pressure relief - review the design there
b. water pumps often have a built in overheat mechanism that shuts them off after a short time running without water or at pressures/temps sufficient to set off the internal sensor (to prevent the motor from seizing up - as it may be designed to assume the water going through will cool the motor).
c. make sure that gravity guarantees the pump ALWAYS has water or you run into the priming issue you mentioned - that may include relocating the pump to underneath the reservoir...
d. as CK said - you don't want too much flow - so double check that and you can add fittings in the lines to slow it down - much like we used to put washers in non-thermostat radiator setups to slow down the water...

OK excuse my ignorance here but isn't the IAT located and measured through the MAF? So it is the incoming air that it measures. And how does the intercooler effect this?

Disconnect the hose at the outlet of the intercooler and run it into a bucket.
This will ensure that there no air pockets in the system.

06gt4rad said:

OK excuse my ignorance here but isn't the IAT located and measured through the MAF? So it is the incoming air that it measures. And how does the intercooler effect this?

Click to expand...

Most S/C'd setups do (or should) measure IAT after the compressor and after the intercooler so that they can see what the temp of the air going into the cylinder is since the compressor heats it up and the intercooler cools it down - its a crude guess otherwise...

So, in these setups the MAF IAT is bypassed...

cekim said:

In addition to what CK said, I was about to post a PS of:

a. sounds more and more like a pressure/cavitation issue when I think about it
- see CK's comments about pressure relief - review the design there

Click to expand...

yep - I didn't see a relief in his pics - I have one right on top.

b. water pumps often have a built in overheat mechanism that shuts them off after a short time running without water or at pressures/temps sufficient to set off the internal sensor (to prevent the motor from seizing up - as it may be designed to assume the water going through will cool the motor).

Click to expand...

Also very important. I have mine wired on all the time as soon as the key is turned. You can easily turn the key and hear it running instantly to know it's working. I also didn't piggy back the pump to anything. I set the fuel pump and IC pump on there own relays and power source directly with a 40 amp fuse.

c. make sure that gravity guarantees the pump ALWAYS has water or you run into the priming issue you mentioned - that may include relocating the pump to underneath the reservoir...

Click to expand...

BIG +1 we changed the original design of mine to place the pump under the car mounted to the spare tire well (my fuel pump is similar located) Taking advantage of gravity is a MUST. If your pic you posted is the pump to the right of the box like I think it is, no good - you want to move it UNDER the resevoir.

d. as CK said - you don't want too much flow - so double check that and you can add fittings in the lines to slow it down - much like we used to put washers in non-thermostat radiator setups to slow down the water...

Click to expand...

Yeah, that one surprised me today. I discovered the pump I bought was actually 'too good' for me...lol. I'm not sure what the flow rate is now, but I am using the Whipple pump. It has been tried and proven with the lightning guys running similar to ours, so I didn't want to change the 'norm'.

oops

cekim said:

Most S/C'd setups do (or should) measure IAT after the compressor and after the intercooler so that they can see what the temp of the air going into the cylinder is since the compressor heats it up and the intercooler cools it down - its a crude guess otherwise...

So, in these setups the MAF IAT is bypassed...

Click to expand...

Yes that i know but my question still remains isn't the IAT located in the MAF so how is it bypassed and then measured?

06gt4rad said:

Yes that i know but my question still remains isn't the IAT located in the MAF so how is it bypassed and then measured?

Click to expand...

An external sensor is added to the system and wired in place of the MAF sensor (the MAF sensor wires are cut and physically bypassed).

cekim said:

An external sensor is added to the system and wired in place of the MAF sensor (the MAF sensor wires are cut and physically bypassed).

Click to expand...

Thank You

Mine is wired always on with the key as well. Considering 20gpm is way above what the Stock KB pump, and the FRPP lightning pump (5gpm) do id say it is not too little at all. A lot of cobra guys use this exact pump with a trunk mountedsystem

The pump is pushing forward, not sucking back already.

As far as i can tell, no bubbling in the hose anywhere and no leaks

The pump has a small sump on it for fluid and the fluid is being drawn from the tank from the bottom of the tank so that is not the issue

I have noticed when i remove the cap from thetank, that there is definitely air escaping when the cap is released, almsot seems as if it builds up pressure in there, though not too much. that might be normal though as it is supposed to be aclosed system i think

With a closed system - that is a small sump - even a tiny amount of air in a pressurized/closed system can cause trouble...

Much easier to have a breather - particularly if you are going to open it up every time you make a run (to put in ice)...

Oh, and you still need to check with KB and address the potentially that you are pushing water through there so fast it cannot exchange heat...

94tbird said:

Mine is wired always on with the key as well. Considering 20gpm is way above what the Stock KB pump, and the FRPP lightning pump (5gpm) do id say it is not too little at all. A lot of cobra guys use this exact pump with a trunk mountedsystem

The pump is pushing forward, not sucking back already.

As far as i can tell, no bubbling in the hose anywhere and no leaks

The pump has a small sump on it for fluid and the fluid is being drawn from the tank from the bottom of the tank so that is not the issue

I have noticed when i remove the cap from thetank, that there is definitely air escaping when the cap is released, almsot seems as if it builds up pressure in there, though not too much. that might be normal though as it is supposed to be aclosed system i think

Click to expand...

Is it possible guys that with the system being closed the way he has it, that it is creating a vacuum effect within the system and then possibly collapsing a hose?. I would think there should have a vent line at the tank.