Engine controls, overheating, and HAI/CAI's
 

For reference, I've done some decent tweeking on Mustangs and their ECU's, and that's where most of my information comes from on this topic. Some things I will state as fact, some I won't, and I will try to be deliberate on this.
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With temperatures outside reaching 90+ and heat indexes in the good old 110's my truck has decided that sitting in stop and go traffic with the air on and pulling a trailer is too much for it. The temperature gauge goes up past the 220 mark, but not quite all the way to the RED ZONE. Now, what does your car do when this happens?

Well, I know that with my mustang ECU, the computer actually RICHENED the mixture some to help it cool down. This may be true across the board, as a lean mixture becomes too lean due to the temperature of the engine. This is opposite of why you need it when your car is cold. The fuel burning helps warm it up, and then it leans it out when you are at operating temperatures. Go PAST operating temperatures, however, and the extra fuel is supposed to help cool it down. Like I said, I don't know if this is true across the board or not, but take it into consideration.

Now, if we're putting on grill blocks, and making our HAI to suck up that heat from the motor, AND it's 90+ degrees out, the computer will start throwing more fuel in there. Not good for fuel economy.

My hypothesis: A HAI will increase MPG's in temps less than 80* and a CAI will increase MPG's MORE than 80*

My testing: I have an intake (properly tuned using calculations for intake size, port size, TB size, cam specs, displacement, etc.) and a make-shift heat shield. When the temps are hot (80+) I will be putting on the heat shield. When they are less, I will remove. Since the next couple weeks look to be in the 90+ range, this shouldn't be too hard to figure my MPG's.

I will also be monitoring the tire pressure, only filling up in the morning before everything has warmed up, and installing or removing the shield itself only in the morning.

My last partial tank I watched it as the engine certainly took longer to warm up, which made me thing I should have a way to close/open it as it warms/cools, but the engineering behind that is just farther than I really need to do atm.

Lemme know what you think and lemme know any suggestions/questions/concerns!
Blu3

Just a quick question , when you say engine reaching 220F is that the point fans kick in or is it going higher after fan are on ?

I have been wondering about this too, but I don't have your experience. So I'll be watching with interest. Quick question: why 80* and not 90* ambient temp as the cutoff?

80'F vs. 90'F must be the point where that engine has to pull back the timing to prevent preinition. When the timing dials back you lose power.

My current truck has a mechanical fan which is probably stuck on all the time. Sure seems like it anyways. After 160* i KNOW it is.

I'm looking into the ECU information for my tuck , but it's hard to tell really.
I had to get a cutoff point, and at 80* F with a grill block, the engine can start to overheat. at 90*+ like this WHOLE week is supposed to be, It WILL overheat.

One hole in this theory, is if the truck does indeed give it a rich mixture like my old mustang did.

Well... a tank done with the shield in. Not a huge difference, but seems better by a bit than the previous.
16.6 mpg.
It's not a huge jump, but I'm going to just go by the thought that in the summer in these 90* days, it's worth it to have. Especially if I would be towing etc.

In the winter... take it out! Get that HAI going.
I will test with another full tanks, as it's above 80 for the rest of the week as well.

That jibes with the experiences in my Buick. With a full grille block my engine temperatures were 188-190*F. The fans were reprogrammed to come on at 186*F. Removing 1/4 of the block let the engine stay below 186*F. My IAT's also came down since I hacked up my airbox to serve as a WAI in the winter, and it was working too well in that fashion.

It looks like big pushrod V6's and V8's don't benefit as much from these mods as much as a smaller OHC I-4 does.

Most of it depends on HOW hot you're getting, and where your engine starts putting in more fuel or removing timing in order to help the overheating engine. Either way is bad for fuel economy. But yes, a 4 banger without a turbo or a hot cam or anything will be in a lighter car with less stress to begin with, which is why they can get away with more.

My truck on the other hand, with a MONSTER grill, and even a scoop in the lower grill to channel MORE air was above the 220 mark and on it's way to the RED ZONE just sitting in traffic with the AC and the HAI. I'd like to design a grille block, but it's just not feasable in this weather. Thus the experiment with the CAI

So far, a small increase. I'll probably mess with switching it back and forth with and without the shield.

either way, I"ll be designing it a bit better and making a more secure solution. Yet, make it removable for winter.