Recovering lost heat energy in engine coolant...

[mechman600]

Awesome work! I wonder how hot is too hot, when IAT is too hot and starts creating adverse effects like retarded timing in reaction to pre-ignition. Just a question - I'm not suggesting that it actually will. And I am sure you will give us the answers soon enough.

You are inspiring me to do the same. I would use a solenoid valve that I could control with a switch in the cabin. That way when I am mountain driving and encounter a massive hill, I switch it to "turbo mountain climb boost mode" to close the valve for a bit more jam.

EDIT: As good as this modification may be for reduced fuel consumption, I wonder how good it also is for NOx production, which would be bad unless the catalytic converter is able to eat the difference. Increased IAT = increased combustion temps = increased NOx. Unless I am missing something, which I usually am.....

[t vago]

Originally Posted by mechman600

Awesome work! I wonder how hot is too hot, when IAT is too hot and starts creating adverse effects like retarded timing in reaction to pre-ignition. Just a question - I'm not suggesting that it actually will. And I am sure you will give us the answers soon enough.

Thanks! This is a good point to consider. How hot is too hot? Nobody seems to know. I am not sure what the engine computer will do. I know that it does not have a knock sensor, though, so I will have to be careful.

Originally Posted by mechman600

You are inspiring me to do the same. I would use a solenoid valve that I could control with a switch in the cabin. That way when I am mountain driving and encounter a massive hill, I switch it to "turbo mountain climb boost mode" to close the valve for a bit more jam.

Be careful of that. With my old setup, it took several minutes for the intake air temperature to stabilize, when the coolant flow was turned off. I imagine that the new setup will take just as long.

Originally Posted by mechman600

EDIT: As good as this modification may be for reduced fuel consumption, I wonder how good it also is for NOx production, which would be bad unless the catalytic converter is able to eat the difference. Increased IAT = increased combustion temps = increased NOx. Unless I am missing something, which I usually am.....

Another good point. I've often thought of that, too.

I am reasonably sure that this will not affect NOx emissions too much. Under normal AFRs, the emissions system on my truck is such that it does both its normal job of oxidizing CO and hydrocarbons into CO2, and it also performs NOx reduction. I am not modifying or altering the AFR, as can be seen on my wideband O2 gauge. This suggest that NOx emissions will be catalyzed out as they would be normally.

However, the reason why I'm seeing such gains in the first place is because the truck engine wasn't really placed under any serious load while commuting. This HAI is effectively reducing the maximum power output of the truck engine, forcing the engine load to become higher as a percentage of its maximum loading. That's an argument that supports the idea that this mod will increase NOx emissions.

So, to be honest, I simply don't know.

[mechman600]

Originally Posted by t vago

So, to be honest, I simply don't know.

Sometimes admitting this is half the battle!

After thinking about it more, your ECU should adjust timing to compensate for hot IAT, eliminating the chance of pre-ignition....to a point. I would guess this to be 150F or so, allowing room above the highest imaginable ambient temps that the vehicle would ever see and heat soak when your vehicle is shut off hot and engine compartment heat gets to the IAT sensor.

I wonder if too hot will trigger a P1192 or P1193 code for IAT sensor out of range. I would suggest that if the check engine light comes on, be careful because the ECU may default to an incorrect IAT value and adjust timing accordingly, allowing the possibility of pre-ignition. However, your IAT will only ever get near coolant temp (~190F), and this is probably still in range.

Excuse my thinking out loud again.....

[user removed]

You have to consider the intake air temperature as mass reduction as well as atomization enhancement. I have seen a thermometer reading of 160 degrees working outside in the sun on an engine, with the hood open. Hot soak temperatures in even not well sealed engine compartments reach a point where fuel under 60 PSI pressure can boil.

All that being said I think the IAT range might vary from brand to brand but at the maximum reading the percentages of density and temperature compared to normal become fairly small.

Higher temp is effective displacement reduction, while higher temperatures will enhance atomization, so you have two benefits. I dont think you will create preignition in this scenario, since you have lower effective mazimum compression as well as better fuel distribution.

Bottom line is the oxygen sensor is the final control of mixture ratios, regardless of what is coming in to the manifold, it is what is going out that creates the voltage reading that the system relies for final mixture adjustments.

That's heck of a nice clean installation t vago, I hope it gets you to 21 MPG average.

regards
Mech

[ProDarwin]

FWIW, several Saturn owners with hot air intakes are reporting ~150F as the highest operating temp before the computer will start screwing with timing. Obviously this will vary from vehicle to vehicle, but just a point of reference.

Originally Posted by mechman600

You are inspiring me to do the same. I would use a solenoid valve that I could control with a switch in the cabin. That way when I am mountain driving and encounter a massive hill, I switch it to "turbo mountain climb boost mode" to close the valve for a bit more jam.

For this you would be better off running an intake with two filters and a diverter valve (I think an exhaust cutout would work well for this). That way you can just switch from hot to cold, instead of turning off the hot and waiting for the temps to cool down.

In regards to the IAT out of range... in my car the coolant temp sensor and intake air temp sensor are the same part number

I look forward to more results from Vago. I may have to get some instrumentation (and I am still torn on what to get) so I can test mine. I've only gone through about 1.5 tanks since the install, so no real data yet.

[Christ]

Originally Posted by ProDarwin

In regards to the IAT out of range... in my car the coolant temp sensor and intake air temp sensor are the same part number

This is probably the case with a large number of vehicles - however, that doesn't necessarily mean that the ECM is expecting the same range of temps from both. In fact, I can guarantee it's not.

If the air temp sensor ever reached over 215degF, You can bet your sweet gas fumes that puppy would kick the CEL on. But for the CTS, that's normal.

[mechman600]

Originally Posted by Christ

This is probably the case with a large number of vehicles - however, that doesn't necessarily mean that the ECM is expecting the same range of temps from both. In fact, I can guarantee it's not.

That's exactly what I meant. The difference in what the ECU is expecting for each sensor.

Here's an air density vs. temperature chart that illustrates what Old Mechanic is saying above:


The difference in density between 70F and 160F is 15%. Can we assume that this difference will equate to a 15% difference in engine load, providing all other variables remain constant?

[t vago]

Originally Posted by mechman600

The difference in density between 70F and 160F is 15%. Can we assume that this difference will equate to a 15% difference in engine load, providing all other variables remain constant?

At full load, I think you can say that. However, for most cars and trucks, that would not necessarily be true because of their partial loading.

I am assuming that chart is for atmospheric pressure, too. If so, then intake manifold pressure would be a fraction of those density/specific weight values. Still, the basic idea behind the chart supports HAI theory in regard to reducing pumping losses.

Heh... I'd love to get a cheapie datalogger...

[ProDarwin]

Originally Posted by Christ

This is probably the case with a large number of vehicles - however, that doesn't necessarily mean that the ECM is expecting the same range of temps from both. In fact, I can guarantee it's not.

Sorry, did not mean to imply that, simply pointing out that the ECU is capable of reading the same range from both since they are electronically identical.


Vago - I'm leaning toward this for data logging (cheaper than scangauge), as it also allows me to data-log my autocross runs:

Kiwi Wifi - PLX Devices Inc - USA

[mechman600]

Originally Posted by t vago

Still, the basic idea behind the chart supports HAI theory in regard to reducing pumping losses.

Yeah, that's what I meant when I mentioned load. Like, if you are steady at 40 mph at 20% load at 70F IAT, I wonder if the larger throttle opening required with 160F IAT would equate to 20 + 15% = 23% load in the exact same situation. It [mostly] boils down to pumping losses. There will obviously be more of a difference at higher loads where the air density difference (ADD - how about coining a new acronym here!) will put a bigger dent in the engine load difference, thus affecting pumping losses.

Heh... I'd love to get a cheapie datalogger...

8226 - CarChip Pro Automotive Logger

Sort of like this. But I have seen even smaller dataloggers for sale in the MAC Tools fliers for around $50. They are tiny and just plug into the OBD port where you leave them. The MAC one (which I cannot for the life of me find online, so it probably does not exist anymore) records the last 24 hours of vehicle data. All you do is hook up to the mini-USB port and download the data onto your computer with the included software. It works pretty slick.