Announcing a complete solution to mapping engine efficiency

[kubark42]

Originally Posted by McTimson

I'd definitely be interested in installing one of these, the only problem for me would be finding the GPS unit. I don't know anything about them, so I'm not really sure what to look for in buying one. I already have an MPGuino set up, so those wires are already tapped, and I have access to Matlab.

Do you know the typical power draw of the GPS units?

It's a pretty large market out there, so it ranges all over the map. The FV-M8 that I have uses about 60mA. The u-blox use about 40mA.

However, one of the reasons I like the u-blox is because it has some nifty shut-down features that let it go to sleep and wake up periodically, all on its own, so power usage becomes much less important. Here's the link: www.lemosint.com/gps/gps_details.php?itemID=571

(Note that if you wanted something like that, you'd have to be able to do some programming in order to support the extended features. It's pretty easy, and I can advise, of course, but without having the GPS unit in front of me I'd be a bit limited. Are you comfortable with that?)

[Daox]

Very impressive work! I haven't read the entire paper you posted yet, but did breeze through it and your dyno map is very close to the one you made yourself.

I also would be interested in doing some testing with you, but would also need a GPS. I also have an mpguino setup in the car already.

[kubark42]

Originally Posted by Daox

Very impressive work! I haven't read the entire paper you posted yet, but did breeze through it and your dyno map is very close to the one you made yourself.

I also would be interested in doing some testing with you, but would also need a GPS. I also have an mpguino setup in the car already.

How do you feel about programming? Since you've got a Prius, you could actually get all the information I'm gathering directly from the CAN bus (http://www.vassfamily.net/ToyotaPrius/CAN/cindex.html), along with a lot of other goodies. Just connect two simple wires and a ground and hardware-wise you're good to go. There'd be a bit of programming on the software side (not much, I've already done most of it), and that'd be it for the logging. I'd be interested to try to build an efficiency curve from a Prius's drive cycle.

[Daox]

I'm comfortable doing some programming.

I was thinking of putting it in the Paseo, but the Prius would be interesting as well. And, my Prius has a GPS in it. I have no idea what kind of outputs it has though. I'd guess none.

[Weather Spotter]

I have a Matrix with a scangauge and a cheep garman GPS unit. would that work or do I need to buy another GPS unit?

[kubark42]

Originally Posted by Weather Spotter

I have a Matrix with a scangauge and a cheep garman GPS unit. would that work or do I need to buy another GPS unit?

That depends on whether the Garmin outputs to a serial port, and whether it outputs a pulse-per-second signal. Do you have the model # handy?

If it does output to a serial port, and not USB, then you'll still need one additional chip. It's called a MAX233, and you can get them for free as a sample from Maxim. Very easy to wire up.

[Weather Spotter]

it is a Nuvi 200, the only port is 1 USB. Does my Matrix have a CAN bus and if so would that save some work?

[kubark42]

Originally Posted by Weather Spotter

it is a Nuvi 200, the only port is 1 USB.

Ah, that won't do it then. My design eliminates the crystal, but depends on the GPS's PPS to keep the RC oscillator in line.

Originally Posted by Weather Spotter

Does my Matrix have a CAN bus and if so would that save some work?

According to Does an '06 Toyota Rav4 have an accessible CAN-bus? - MP3Car.com it does not. Moreover, it would actually take more time, believe it or not, because the CANbus protocol would have to be reverse engineered. I've already done it for the Smart Roadster, and it's a PITA. Someone else has already done it for the 2006 Prius, so I could base things off that information. But for another car...? There's no way of telling what we'd find in there.

You see, there's no standard for what information a manufacturer puts on its CANbus, and there's no (legal) requirement for them to divulge this information, so it's sort of the wild west in there. That might explain why it's said that there are more lines of code in your navigation system than there are in the whole Airbus A380.

Anyway, the CANbus reader is something you would have to buy for around $75. It's not something that I have here in my lab, so if you're on a student budget the original approach is cheaper.

[RobertSmalls]

The biggest problem I see is with the inputs for the road load equation: M, Ma, Cd*A, Crr. M varies quite a bit. For example, my car sheds 27kg as the fuel tank runs from full to empty. I've removed some parts and added others, so if I wanted to know my car's mass, I'd have to have it weighed.

My Cd*A changes with every aeromod I do, and Crr depends on tire temperature, pavement type, and too many other factors. I think the best approach here is to have the user do a high-speed neutral coast to discern Cd*A and a low-speed coast to determine Crr. I think lots of EcoModders would like to have a precise datalogger to help calculate these numbers.

I would love to study the BSFC of the first-gen Honda Insight. I'd love to quantify the effect of lean burn, find the optimal rate of acceleration, and study exhaust and intake mods.

How long does it take to fill the 2GB SD card?

[McTimson]

Programming the stuff is no problem, as long as it's nothing too difficult, I think I'll be able to handle it.

GPS things are something that I've just never really looked into, I didn't even know you could buy separate chips like this before reading your report, so that's really my only concern - I don't know any of the features, benefits of one vs. another, etc. But recommend me a decent, cheap one, and I'll be all over it.