Air intake temperatures

HER_CRD · **Posted:** Mon Jun 12, 2017 8:05 pm

I've read more than a few times that the CRD engine doesn't benefit from having extra are from mods like the gasser air box. But what about cooler air intake temperatures? Today with a 75℉ ambient I was getting a temp rise for intake air (reading from Torque Pro) of 25 - 30℉.

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HER_CRD · **Posted:** Mon Jun 12, 2017 8:09 pm

Somehow I posted this twice. Please help to keep responses to one thread.

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flash7210 · **Posted:** Mon Jun 12, 2017 8:54 pm

The only advantage that the 3.7 V6 airbox provides is a air inlet that is a few inches higher and less likely to suck in water.

Intake air temp that is ~30 degrees above ambient is pretty normal for this engine.

In the past I have considered open-conical air filters a bad mod because they draw in too much hot air from under the hood. However, now that I am running that type of filter (a.k.a. cold air intake) I am seeing that my IAT is no hotter than before.

Lately, my afternoon commute home sees ambient temps in the low 90s.
My IAT is about 120F with the AC off.
With AC on its 130-140F.
While stopped, IAT will slowly creep up due to lack of airflow through the intercooler.
Once moving again it will slowly drop to normal levels.

HER_CRD · **Posted:** Mon Jun 12, 2017 9:20 pm

30℉ just seems way high, but for my work I'm allowed 15℉ from ambient to turbo inlet (design engineer for a diesel engine distributor).

You might be right on your temperatures from using the cone filter. Being in the front corner of the engine bay there shouldn't be much hot air unless your parked or cruising at an idle.

Does the air box get heat soaked?

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flash7210 · **Posted:** Mon Jun 12, 2017 9:28 pm

HER_CRD wrote:

30℉ just seems way high, but for my work I'm allowed 15℉ from ambient to turbo inlet (design engineer for a diesel engine distributor).

You might be right on your temperatures from using the cone filter. Being in the front corner of the engine bay there shouldn't be much hot air unless your parked or cruising at an idle.

Does the air box get heat soaked?

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Not really.
But the MAP sensor, which is where IAT is measured, is in the top of the intake manifold and it gets heat soaked.

If you think IAT is too high, install a better intercooler.
And once you figure out how to do that, post a good how-to for all of us to follow. :wink:

HER_CRD · **Posted:** Mon Jun 12, 2017 9:38 pm

OK, that makes more sense then that temperature is being measured at the intake manifold rather than out of the air box.

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mass-hole · **Posted:** Wed Jun 14, 2017 2:43 pm

HER_CRD wrote:

OK, that makes more sense then that temperature is being measured at the intake manifold rather than out of the air box.

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Yeah you gotta remember these things are running at a 2.3/1 pressure ratio when they are at full bore so that intake air is being heated to like 300+ degrees by the turbo. Even in steady state cruise it still runs a good amount of boost so its probably in the 200's pre-intercooler. The air box may make a SMALL difference, but ultimately its to pressure ratio, compressor efficiency, and CAC efficiency that make the most difference.

That said, my IAT's never drop below ~110F even if I coast downhill for 3 minutes straight on an 80F day. That tells me the TMAP sensor is not accurate and is heat soaked by the manifold or the intercooler is heinously inefficient. My guess is its a little of both. I have seen close to 200F IAT's on long hill climbs with the A/C on which is more a result of poor intercooling efficiency. That means the intercooler is only giving us about 50% efficiency which is not great, but it makes sense being its behind the A/C condenser so the cooling air is pre-heated.

I am planning on doing a ~20"x10"x3" intercooler mounted in front of the A/C condenser, that way its got more volume than the stock CAC but has direct cooling flow and leaves the bottom half of the radiator and condenser open to fresh cooling air as well. Should help the whole cooling system be more efficient.

flash7210 · **Posted:** Wed Jun 14, 2017 5:38 pm

Mass,
Your IAT is not too far out of line.
I would expect IAT to be quite high when in the summer, AC on, climbing a hill, and at high boost.
Especially considering your high altitude and lower air density.
But still, the factory intercool still kinda sucks.

On ebay I found a 29x11x3 intercooler with a 24x11x3 core.
Seems like a good size that wont block any of the radiator.
The problem is getting it to fit.

I've also considered getting the larger V6 condenser that doesnt have the integrated transmission cooler.
This should help dissipate heat over a broader area making it more efficient.
I would then have to rely solely on a after market cooler for the transmission.

mass-hole · **Posted:** Wed Jun 14, 2017 8:57 pm

flash7210 wrote:

Mass,
Your IAT is not too far out of line.
I would expect IAT to be quite high when in the summer, AC on, climbing a hill, and at high boost.
Especially considering your high altitude and lower air density.
But still, the factory intercool still kinda sucks.

On ebay I found a 29x11x3 intercooler with a 24x11x3 core.
Seems like a good size that wont block any of the radiator.
The problem is getting it to fit.

I've also considered getting the larger V6 condenser that doesnt have the integrated transmission cooler.
This should help dissipate heat over a broader area making it more efficient.
I would then have to rely solely on a after market cooler for the transmission.

eBay cores can be a little scary. They tend to be low density and I've seen pictures of some that literally don't have turbulars on the inside which means really poor heat transfer. I would see if you can find a Treadstone in a size you like as they at least are well known, cheap, and decent performing

Another option I found is bell intercoolers. You can custom order online from a massive array of core sizes and end tank designs. They are pricey, but are built extremely well. One of their engineers specd out a 18x10x3 for me as the appropriate core size for up to 300 hp, so it will handle anything we can throw at it. 10" was what I told them I wanted for height.

Bell is really conservative on their core ratings, if you looked at the same size core from any other company they would rate it for 500-600 hp or more.

GordnadoCRD · **Posted:** Wed Jun 14, 2017 10:39 pm

One other problem with the OE CRD setup, is the huge edge air gap between the radiator and the intercooler. (Mostly top and bottom ) The engine fan pulls huge amounts through the radiator, that enters behind the intercooler, further reducing it's effectiveness.

mass-hole · **Posted:** Wed Jun 14, 2017 11:07 pm

GordnadoCRD wrote:

One other problem with the OE CRD setup, is the huge edge air gap between the radiator and the intercooler. (Mostly top and bottom ) The engine fan pulls huge amounts through the radiator, that enters behind the intercooler, further reducing it's effectiveness.

I actually stuffed that foam pipe insulation from Home Depot along the sides and bottom between the radiator and cac to help seal it up. When I was having overheating issues I thought it might have been a problem with hot air from inside the engine bay being recirculated back through.

Turns out the HD Hayden fan clutch I bought was DOA. Once I got the fixed flex fan and shroud in place I have zero over heat issues. I am even running a 400 ft-lb tune now and can scoot up I80 locked in 5th with the A/C blasting and the temp doesn't budge.

DieselJeepLuvr · **Posted:** Wed Jun 14, 2017 11:36 pm

GordnadoCRD wrote:

One other problem with the OE CRD setup, is the huge edge air gap between the radiator and the intercooler. (Mostly top and bottom ) The engine fan pulls huge amounts through the radiator, that enters behind the intercooler, further reducing it's effectiveness.

Most all diesels have that. Manufacturers are more inclined to sacrifice performance for cooling efficiency. One thing I have suspected is how much of the stock intercooler is clogged with crud formed from the oil vapor that comes from the stock CCV tube combined with dirt particles that get past the air filter. That's got to affect heat transfer.

GordnadoCRD · **Posted:** Thu Jun 15, 2017 6:19 pm

mass-hole wrote:

I actually stuffed that foam pipe insulation from Home Depot along the sides and bottom between the radiator and cac to help seal it up. When I was having overheating issues I thought it might have been a problem with hot air from inside the engine bay being recirculated back through.

Turns out the HD Hayden fan clutch I bought was DOA. Once I got the fixed flex fan and shroud in place I have zero over heat issues. I am even running a 400 ft-lb tune now and can scoot up I80 locked in 5th with the A/C blasting and the temp doesn't budge.

I did the same thing with the pipe insulation, around both the Radiator-intercooler gap, and the intercooler-condenser gap. My hayden clutch seems to be working fine, it rarely engages, even when idling for extended periods, and when it does engage, it pulls enough I can feel it at the front of the grille, and it slowly spins the electric fan when it's not powered.

DieselJeepLuvr wrote:

One thing I have suspected is how much of the stock intercooler is clogged with crud formed from the oil vapor that comes from the stock CCV tube combined with dirt particles that get past the air filter. That's got to affect heat transfer.

I agree about the oil in the intercooler. In my case when it was completely flooded with engine oil up to the level of the CAC outlet, it took 2 weeks of daily flushing, rinsing, using a bunch of Dawn dish detergent, as well as cooling system flushing product, and building special plungers adapted to the inlet and outlet to give a washing machine effect back and forth through it, before it stopped having oil coming to the top.

DieselJeepLuvr · **Posted:** Fri Jun 16, 2017 3:27 pm

GordnadoCRD wrote:

In my case when it was completely flooded with engine oil up to the level of the CAC outlet, it took 2 weeks of daily flushing, rinsing, using a bunch of Dawn dish detergent, as well as cooling system flushing product, and building special plungers adapted to the inlet and outlet to give a washing machine effect back and forth through it, before it stopped having oil coming to the top.

Great idea! I was thinking about unhooking both the hoses on both the inlet and outlet and slowly filling it with boiling water. Then just letting the oil float to the top for easy removal but I like the idea of filling it afterwards with soapy water. I'll have to try it.

GordnadoCRD · **Posted:** Fri Jun 16, 2017 5:24 pm

This was done with the CAC out of the vehicle with front side to the lawn and the hose mounts facing up so the loosened oil would rise to the surface. I'm fairly certain that a ultrasonic cleaning would be better and faster, but I didn't have one available.

Bushman5 · **Joined:** Sat Jul 11, 2015 11:05 am **Posts:** 276

time for Sasquatch Parts to design and build a DRY ICE box for the front of the CRD.... :ROTFL:

Air intake temperatures

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