Before I start measuring the fuel economy I am going to try to get more separation of the IAT while cruising.
I will put the original plastic tube from the filter case to the passenger's fender, so the engine can get cold air from the outside instead of the engine bay, and cold down the thermo-sw inside the filter case and restart the heating process faster.
Power is nothing without control
It took me half an hour to put the tube in place. Just waiting for my night trip to report back how it works with outside air compared to taking the air from the engine bay.
Power is nothing without control
It looks like I was able to raise the temp from an average of 47 to 55 degrees C when cruising.
Its not the best temp control, but I care for the average only. No more charts for now. I'm ready to start measuring the fuel economy.
I didn't do anything new, just reassembled what the honda engineers designed in the 80's.
Power is nothing without control
OK, One more chart.
This is turning out better than expected. I already showed in below charts that once the engine is fully warm, after 10 minutes of driving, the IAT gets pretty stable at around 47 C due to the heat generated in the engine bay. With or without air heater connected.
With the combination of the hot air hose and the cold air from outside of the engine bay, I raised the temp as much as 87 C when idling and as low as 24 degrees when accelerating. I think its good because it will give more power when I need it and fuel saving when required.
If you see the red line, everytime I accelerated, the door opened and let the cold air get into the engine. And immediately closed and raised the temp again after the pedal is released. It happens automatically over and over during the whole drive.
If this don't meet my expectations for fuel economy, then I plan to put another sort of temperature control, so I avoid it to go too cold. For now I will be driving like this for a couple of weeks and see what happens.
Power is nothing without control
this is amazing to be able to see the data measured as results and not just guessing, very impressive work!
+1 I really enjoy following your projects here Buzo. Your custom OBD board for carb'd 3Geez is amazing. Thanks for all your work here.Originally Posted by 2oodoor
Thanks again for your comments! I only hope to get a measurable difference in fuel economy, don't care if its lower or higher at this point. We can always justify why the data didn't follow the theory haha.
I filled the tank up this morning, I'll wait 100 Miles and fill it up again and record gallons/100 Mi. The car has both, hot and cold hoses connected for this first fuel economy measuring. Then run for another 100 Mi with the hoses disconnected, and compare.
Whatever happens, I am going to keep both hoses connected in the car. It certainly feels different. Better.
Power is nothing without control
Sorry I did it again here with multiple posts... butterfingers.
My old 88 DX carb is still 100% stock in there with the hot air pipe. The intake air control diaphragm I replaced a few years ago when I went through a troubleshoot. It then checked out functional and also replaced the choke opener and a thermovalve. I can't say what effect it had on gas mileage as the choke opener was what put the dent in my mileage. I don't know for how long that intake air control diaphragm was bad. My old beater gets about 28mpg in town and 34-36 mpg hwy.
Last edited by g.frost; 11-15-2012 at 08:46 PM.
My old 88 DX carb is still 100% stock in there with the hot air pipe. The intake air control diaphragm I replaced a few years ago when I went through a troubleshoot. It then checked out functional and also replaced the choke opener and a thermovalve. I can't say what effect it had on gas mileage as the choke opener was what put the dent in my mileage. I don't know for how long that intake air control diaphragm was bad. My old beater gets about 28mpg in town and 34-36 mpg hwy.
Looking forward to the results of your tests.
Only 80 Miles since I filled the tank... will wait until get 100 just to be consistent.
In the mean time, I painted my valve cover and converted my old dizzy into a cam sensor.
Power is nothing without control
Completed 100 miles with the hoses connected and have accumulated 40 miles with the hoses disconnected so far.
I don't know which one will be better in fuel economy at this time.
Honestly, I never used the full-empty-full technique before, so the MPG I got after 100 miles is way below my previously calculated MPG.
Power is nothing without control
Yeah, relying on the gas pump shut-off when filling up is not going to produce a consistent reliable result. 100 miles is maybe 4 gallons so the 'fill-up' pump shutoff will give you a larger % error than filling an empty tank with 12+ gallons to average out the error. I check mileage at every fill up with the trip odometer, and average from that.
I'm trying to minimize the variables by using the same pump in the same gas station, same hour of the day, etc. I am repeating even the number of times the pump shuts off before stop filling. But you are right, 100 miles is too low, 5 miles would be equivalent to 1 MPG.
Another idea is to combine the data from my HUD, fuel level and MPH to come up with an instant MPG value. So I'll measure the fuel level when the car is steady in my garage, then accumulate the miles of the day/week and re-measure the fuel level when I'm back at home.
Power is nothing without control
There is a measurable difference. But it looks like the car likes more a constant intake air temperature than higher peaks but lower valleys.
Hoses connected: 19.7 MPG (car feels stronger than ever)
Hoses disconnected: 21.2 MPG (heard a little knock one time)
This is just the beginning. I plan to add an external door control so the temp spikes are minimized and I can set the idling IAT higher.
I like how the car feels when the door opens and lets cold air enter during hard acceleration though.
Power is nothing without control
from what you are saying its a 8-9% difference, i would say that is impressive to see a swing like that. I would still keep collecting more data to confirm this
1989 Accord Lx-i hatchback (current DD project)
1986 Olds Cutlass 442 clone (never ending project)
3Geez resident body man
Owner of Wreck-less auto body
I ran the car with the hot hose connected and the cold hose disconnected. Once the car is hot, the IAT gets pretty stable at around 55 C. Got 23.4 MPG.
in summary:
Hot/Cold hoses connected: 19.7 MPG
Hot/Cold hoses disconnected: 21.2 MPG
Hot connected/Cold disconnected: 23.4 MPG!
The next step is to use the Solenoid C valve that I have in my car to make the air temp get as hotter as I can without jeopardizing the idle, and connect the cold hose to help with hard acceleration.
Power is nothing without control
I wonder if there would be away to add a hot air pipe to a multi-port fuel injection system, and I wonder if it would help.
I did some reading on gas vaporization technology a couple years ago. Supposedly, any way of heating up the mix prior to combustion will yield significantly better mileage. I never tested any of it so I am not sure if it actually works.
Buzo, I'm not sure what your interest is in this, but the book I read claimed that simply heating the gas up to coolant temp is supposed to yield very impressive mileage improvements. You can simply run a copper fuel line around or through a coolant line. Beyond that, heating up the mixture to exhaust temps before it goes into the combustion chamber gives genuinely astonishing MPGs, but that gets a lot more complicated.
Dr_Snooz
"I like to take hammers, and just break stuff, just break stuff." - Beavis
1989 Honda Accord LX-i Coupe, 240k miles, MT swap, rear disc swap
Shop manual downloads available here: CLICK TO VIEW
There is no specific reason for doing this. I realized that, from the several factors affecting the fuel equation, the air temperature was the only thing I could change. The temperature control was already there for me. I just had to connect a couple of hoses and that was it.
Thanks for the tip of heating the fuel too. It makes sense because the air I heat up is cooled down by the fuel spray. Its certainly something I would like to test.
I think I can run a fuel hose all the way around the filter inside the filter case, so air and fuel will be always at the same temperature.
During all this time without posting an update I probed the measuring method was repeatable, I got 0.3 MPG difference between refilling after 100 miles and refilling after the tank was almost empty. I'll stick with the 100 miles refill because its faster and cheaper.
Power is nothing without control
I added the new temp control so now I can set any temperature I want between ambient and the coolant temp.
The pic is divided in 3 parts, the first is how the IAT is controlled by the carbed style temp control with this setup I got 23.4 MPG.
The middle part is a test I ran in my driveway to make sure the connections were right, so I set 40C as the limit for tempo control. It passed OK.
The third part is a short drive I did after I set the temp to 80 C. This is how I am going to run the car for my next 100 miles.
Power is nothing without control
Can I ask what kind of software your using on your laptop to look at oscilloscope readings like that? Your findings are very interesting.
I am using a Megasquirt controller in my car and their TunerStudio software. So all the information is processed by the megasquirt controller and sent through the serial port to my laptop.
You know, with all I have learned in the last two years we can adapt our ECU (EFI or carbed) to talk to TunerStudio... Its going to be a "read only software" but it sounds like a cool project!
Power is nothing without control
This is today's chart with the IAT temperature control set to 80 C compared against an old chart when I was taking the air directly from the engine bay.
Both readings were taken during the same trip, like 10 miles long, at the same hour of the day.
The little door in the air tube intake is vacuum controlled, so when the MAP is above 65 kPa, there is not enough vacuum to keep the door open and cold air is allowed to enter. Which is good because the engine can get more power with colder air than hot air.
I was able to reduce the gamma-enrichment value from 97 to 87 which is a 10% reduction. It means that the ECU is certainly sending less fuel.
Didn't notice any change in performance.
Power is nothing without control
If the results are worth, we can find a way to get hot air by adding a piece of sheet metal to the exhaust manifold, and the right thermovalve from the thousands used in our cars.
Power is nothing without control
I dont actually use an O2 sensor, so I was thinking I could use the bung hole for that. I would really like to use it to build an EGR, but they are all generally computer controlled. I am always looking for ways to improve gas mileage without loosing daily comforts of the vehicle. AS far as vaporizing fuel, I have hear A LOT about this. It is proven that vaporized fuel is way more efficient then liquid fuel. I think the problem is that it has to be super heated, and that can be very dangerous. I currently plan on running RDX fuel injectors as the atomize the fuel more efficiently. So where exactly is the heater hose going? Is it heating up the air going into the carb, or after the carb?
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