Turbo Intercoolers Air/Air or Water/Air?

[CTX-SLPR]

That's why I said nothing cools better than water. Even at ambient temps the water needs a smaller footprint to do the same job.

You're doing something wrong if you are getting phase changes inside of your liquid-to-air intercooler...

You are correct that there is better heat transfer but the heat rejection to the environment isn't as good with the liquid system. A liquid-to-air system will run at a higher temperature over ambient than an air-to-air due to the hold up inverse of it pulling the heat out of the charge, the radiator just can't work well enough. You also run the risk of a like between pieces that hydrolocks your motor vs. just bleeds your boost off.

I'm put a liquid-to-air on my LSR car since I want dead stable below ambient temperatures but I only have to do it for 5mi at a time.

[BigAL]

You are correct that there is better heat transfer but the heat rejection to the environment isn't as good with the liquid system.

So are you saying using a radiator and coolant to cool your engine is an inefficient way of cooling it?


Just like with the cooling system for your engine, you have to properly size the radiator(heat exchanger) to the heat that is being produced. So hooking a small radiator to your resevior for your intercooler if properly sized should keep the intercooler coolant temps from climbing, just like the radiator in your car keeps your car from overheating.

Also what kind of temps are we talking about? At idle?, at Cruise? at WOT? and at that, how about how much boost are you running as this all factors into what the air temps will be. I'd tend to guess that you don't see post turbo/pre-intercooler air temps more than 150 degrees on a 100 degree day, so really how much is that water in that intercooler resevior being heated up?

[CTX-SLPR]

So are you saying using a radiator and coolant to cool your engine is an inefficient way of cooling it?


Just like with the cooling system for your engine, you have to properly size the radiator(heat exchanger) to the heat that is being produced. So hooking a small radiator to your resevior for your intercooler if properly sized should keep the intercooler coolant temps from climbing, just like the radiator in your car keeps your car from overheating.

Also what kind of temps are we talking about? At idle?, at Cruise? at WOT? and at that, how about how much boost are you running as this all factors into what the air temps will be. I'd tend to guess that you don't see post turbo/pre-intercooler air temps more than 150 degrees on a 100 degree day, so really how much is that water in that intercooler resevior being heated up?

I think you are making my point for me... you put a big enough radiator in the system you can reject the heat to the environment well enough. At that point however you are starting to approach the size of an air-to-air core and your point about packaging becomes moot.

Moreover, everytime you have a transfer of heat, you will be left with a tailing convergence to equilibrium. Newton's law of cooling states that your time rate of temperature change is driven by the difference in temperature so your exchange at close to equilibrium is relatively slow. Your radiator just has to cool water down to "cool enough", not ambient so you can dump a lot of heat quickly. Your radiator on a liquid-to-air intercooler IS trying to reach equilibrium (if you are shooting for ambient charge temperature) so you need to to spend a lot of time trying to dump that heat. With the liquid-to-air you will have one heat transfer to the liquid,so one tailing equilibrium, and then another to dump the heat to the environment. With an air-to-air you only have a single transfer. However you actually have 2 transfers in each step since you need to get the heat from the charge to the aluminum and out of it to the cooling medium. So a liquid-to-air intercooler having twice as many steps now has 4 tailing equilibrium steps instead of 2. All of that adds up to less ability to dump heat.

Bottom line, unless you can artificially drive your temperature difference to greater than the air-to-air, you will pay the price of more transfers. Daily driver, I'd use the AC idea since your time off boost is high to being on. Endurance race car, air-to-air since you either eat HP to drive the cooling equipment (which thermodynamics says will cost more energy than the gain from cooling the charge) or suffer higher charge temperatures. Limited used race cars like drag, autocross, and LSR can use a liquid setup if they ice down the reservoir. Likewise they can have the aero gain from not having to have a radiator but your intercooler then is basically a heat sink.

[TheSilverBuick]

I'd tend to guess that you don't see post turbo/pre-intercooler air temps more than 150 degrees on a 100 degree day, so really how much is that water in that intercooler resevior being heated up?

That about sums it up.

[TheSilverBuick]

Hey, what happened to the post where BigAl was telling me the turbo outlet temps are only 150ºF on a 100ºF day because he looked it up? And how much air the air/air cooler would see on a Firebird?? Google remorse?

[greenjunk]

LOL at the 150* try more like 250*+ easily. with W/A or A/A its packaging, what will fit in the space you have and what is the most efficient. Thats more vehicle specific then anything. If I had my choice with endless space I would choose an air to air in a box full of ice water but few people have the space. Because you don't like my Alky control idea, I vote Water to Air with a high quality exchanger in front of the radiator.

[BigAL]

LOL at the 150* try more like 250*+ easily. with W/A or A/A its packaging, what will fit in the space you have and what is the most efficient. Thats more vehicle specific then anything. If I had my choice with endless space I would choose an air to air in a box full of ice water but few people have the space. Because you don't like my Alky control idea, I vote Water to Air with a high quality exchanger in front of the radiator.

When intake temps go above 140 degrees you will start experiencing detonation and it'll also cost you power. the 100-150 degrees I'm talking about is when cruising down the road under light to non-boosted conditions. Also the only guys I see talking about intake temps above 200 degrees are guys running 40psi of boost or more at WOT. The reality of it is there are so many factors and variables that determine what your intake temps could be that none of us can really say for sure what the intake temps would be coming out of the turbo without actually testing the specific setup. Basically every system is going to act differently. Also if you do a little research you'll find that guys running lower boost levels will see lower increases in intake temps more in line of what I'm talking about, or at least that is what they are claiming they are logging.

This also kind of has me thinking, wonder how much that 6-71 is going to heat the air on the 496 I'm building, maybe I can get Rick to log post blower temps and we can see which heats the air more, turbos or blowers.

[dieselgeek]

When intake temps go above 140 degrees you will start experiencing detonation and it'll also cost you power.

none of us can really say for sure what the intake temps would be coming out of the turbo

well the second one is closer to being right

[greenjunk]

LOL @ geek. A centrifugal blower will make well over 200* out of the outlet and its not getting heat soak from the exhaust. Had a customer with an '01 Z06 with a 427 and D1SC that had before and after cooler temp sensors in the pipes. The crappy intercoolers from procharger only cooled about 100* in the NC summer hence we removed the coolers and went alcohol injection... Much better results and knock protection from the additional octane.

[BigAL]

LOL @ geek. A centrifugal blower will make well over 200* out of the outlet and its not getting heat soak from the exhaust. Had a customer with an '01 Z06 with a 427 and D1SC that had before and after cooler temp sensors in the pipes. The crappy intercoolers from procharger only cooled about 100* in the NC summer hence we removed the coolers and went alcohol injection... Much better results and knock protection from the additional octane.

Sure at WOT you may see temps that high, but what about at cruise when boost isn't being made?

And about the intake air temps being above 140 degrees and causing detonation, guess Ford might know something you guys don't?

15630 - LACKS POWER IN HIGH TEMPERATURES - REPROGRAM PCM
Some 2000-2002 Expeditions equipped with a 5.4L 2V engine may exhibit a lack of power condition when operated in ambient
temperatures above 100 degrees F, particularly during stop-and-go driving. This may be due to PCM calibration, which
retards the ignition timing to prevent detonation when the inlet air temperature (IAT) reaches above 140 degrees F. A new
calibration is available to service this condition. If the condition occurs only when the IAT is above 140 degrees F,
reprogram the PCM to the latest level via the just-in-time process if your WDS communicates w/Fordstar. Also obtain
calibrations on the Ford Professional Technician Society (PTS) website - select 'WDS' then 'PCM reprogramming' and
click 'Instructions' for downloading. Calibrations are scheduled to be included in WDS release B17.10.

15431 - LACK OF POWER IN HIGH AMBIENT TEMPERATURES
Some 1999-2002 Expedition and F-150 vehicles equipped with 5.4L 2V engine may exhibit a lack of power condition when the
vehicle is operated in ambient temperatures above 100 degrees F, particularly during stop-and-go driving. By design, the
PCM calibration retards the ignition timing to prevent detonation when the inlet air temperature (IAT) reaches temperatures
above 140 degrees F. If the lack of power condition occurs only when the IAT is above 140 degrees F, do not replace parts
in an attempt to service. Engineering has developed a new calibration which will be available early in the first quarter
of 2002. If the condition exists in other temperature ranges, proceed with normal diagnostics.

[TheSilverBuick]

Sure at WOT you may see temps that high, but what about at cruise when boost isn't being made?

And about the intake air temps being above 140 degrees and causing detonation, guess Ford might know something you guys don't?

Heck, I've seen over 140ºF intake temps on both my naturally aspirated EFI engine when just cruising around on hot days. Going down the highway my Skylark runs 20-30ºF above ambient and the Firebird for some unknown reason runs 30-50ºF above ambient (I speculate the hole in my hood is pulling exhaust heat upwards rather than cool air downwards...), and then simply sitting in traffic or on surface street driving in summer around Las Vegas or southern California the intake temps are easily over 150ºF on both cars. Since we are talking out of boost, part throttle, these are real world comparisons.

Its in boost we actually really care about. If anything, part throttle driving around intake temps of well over 200ºF could help improve fuel economy.

[TheSilverBuick]

And pulling timing at higher IAT's is nothing new. I've been doing that with the mega squirt on my Skylark since 2009 and my first summer trip to Las Vegas's heat. No different then getting the wrench out and backing off the distributor when its hot out, well except it does it automatically now.

[BigAL]

Heck, I've seen over 140ºF intake temps on both my naturally aspirated EFI engine when just cruising around on hot days. Going down the highway my Skylark runs 20-30ºF above ambient and the Firebird for some unknown reason runs 30-50ºF above ambient (I speculate the hole in my hood is pulling exhaust heat upwards rather than cool air downwards...), and then simply sitting in traffic or on surface street driving in summer around Las Vegas or southern California the intake temps are easily over 150ºF on both cars. Since we are talking out of boost, part throttle, these are real world comparisons.

What does that tell you?

[dieselgeek]

What does that tell you?

That you desperately want people to think you know about any of this stuff

[William Wilson]

Since this is apparently a vote.

I vote for air-to air.

With maybe methanol or at least the set-up to add a system.