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Old 03-05-2010, 10:51 PM   #1
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Lightbulb anyone good with a computer?

I was just reading the thread about the guy thats new to RC an having alot of trouble tuning in the cold, an realized, maybe its time for something better... I was thinking does anyone remember the crude multiport injection systems from when cars just went to FI. What I was thinking is with a on board microprocessor an the technology in our world today, why are we fighting with Carbs still. I need someone thats good with a computer to tell me what I'm up against here. What I wanted to do I have a onboard processor, an feed it air temps and pressure, From there remove the carb an fabricate a tube that extends to the forward part of the truck, have a intake up there where the cold air is, and then have a air speed sensor in the pipe to allow the computer to calculate the mixture it would need to make with the injector. I was thinking because this is only a single cylinder engine, this shouldnt be a massive problem. The only thing I can think of so far is where to find these items an how to program them to work in harmony. Also a simple O2 sensor would need to be incorperated into the system so the computer knows how efficently the engine is burning the fuel, and all these readings would need to be recalculated in preferable micro seconds, if not tenths of a second so the engine is constantly happy, wether its in a turn, going up the face of a jump, or going air plane mode for a brief time. I know they make ESC's that are computer programmable so one can get a basic dyno sheet and adjust a power curve to there liking [so the guy at the LHS said]. Now please comment on this idea, an if anyone would know where to begin please steer me in that direction, because if this is successful it could revolutionize the hobby an make it user friendly for all.

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Old 03-05-2010, 10:59 PM   #2
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good idea but the problem is, it would cost a lot to do that.
if you run it in the cold just, richen the top end needle a bit.
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Old 03-05-2010, 11:46 PM   #3
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I'm in Florida, the weather in the summer rarly changes here, its just hot lol. I figured this would be a good idea to get rid of all the head aches that come with tuning these carbs.
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Old 03-06-2010, 01:44 AM   #4
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atmel avr are fairly easy to program, you can find all the sensors on jameco.com and on digikey.com. You will also need a way to control the fuel pressure. Right now its controlled by the exhaust maybe it needs a fuel pump. btw avrs are better because they have built in a2d converters.
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Old 03-06-2010, 01:48 AM   #5
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Fine concept; but look at the complexity you're talking about adding in total.

Weight of ea. component, plus wiring, plus having to diagnose another system of parts...you'd have 2-component systems that could be causing the problem. The new "computer FI" system and the mechanical throttle body that would still be sitting there.

It's hard to get much simpler than a carb. They're simple, durable, and they work.

Unless you had a personal trained monkey to turn the screws for you, it can't get much easier.

Is there a learning curve? Sure. Can they drive you nuts if you have a small air leak? Yep. But it's up to you to diagnose it reasonable quick; there's a limited number of things that can be wrong and diagnosis generally doesn't take that long once you start down a checklist.

Remote (from your transmitter) needle adjusters (on aircraft at least) and fuel pumps have been tried in the past. I don't think the pumps worked out too hot in high RPM and quick-transitional RPM applications. Plus they're a little heavy once you get one reliable.

You would probably want to monitor your engine running temp, as well as the ambient air temp. However, most ambient temp sensors that are reasonably priced/readily available are kinda big and require a 5V reference signal (most real vehicle applications).

Good luck if you decide to try it out. I'm sure it can be done
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Old 03-06-2010, 01:54 AM   #6
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I would think after all the wizz bang stuff it would weigh a ton. Lets keep it simple aka the Kiss way. If you get a gold plated screw driver it'll almost tune it's self.
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Old 03-06-2010, 02:31 AM   #7
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mbl you present alot of good points about the weight an power issues....carbon fiber everything n lipos... jk jk. I don't know, I'm gonna have to sit down with a piece of paper an put some serious thought into this one, an for the throttle body I was planning on cheating an using a rotary or slide carb housing >.> . You also had a great point about the diagnostics, I refuse to try to put a OBD II style system into a RC car at this point in my life, maybe when I'm older with way to much time I'll try something like that lol. I was also thinking if I were to go to all the trouble to make a EFI system, how much more work would I have to do to make a 4 stroke RC motor, then again thats probably up there with trying to think of a way to make a t-maxx with a 6 speed lol.O and by the way, you know anyone whos selling said monkeys . So let me recap, I would need a O2 sensor, varible pressure fuel pump, temp sensor for the motor, a ambient air temp an pressure sensor, I would also need a fuel gauge so the car wouldnt start to lean out apon fuel depletion which would send all calculations out the window, This may be a little more in depth then I thought. Keep adding input y'all I would love to try an go somewhere with this one.
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Old 03-06-2010, 06:18 AM   #8
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i really hope someone can make this happen. Engine tuning used to be part of the fun. Not anymore. If you are not good at it, it will cost you lots of money replacing/rebuilding motors, not to mention never getting you engine to run right.

It is becoming somthing that i loath now to some degree. Engine tuning has taken alot of fun out of it.
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Old 03-06-2010, 06:22 AM   #9
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I would think after all the wizz bang stuff it would weigh a ton. Lets keep it simple aka the Kiss way. If you get a gold plated screw driver it'll almost tune it's self.
the sensors and procesors would weigh hardly anything. Fuel pump would be the chalenge.

I would love to see a 4 stroke, if someone could get it to rev high enough. It would last alot longer with piston rings.

I am tired of rebuilding and replacing motors. I am starting to get jealous of the electrics. I thing i might be getting one.
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Old 03-06-2010, 06:31 AM   #10
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Go speed density and kill the o2 sensor?
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Old 03-06-2010, 06:55 AM   #11
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Quote:
Originally Posted by Cisco904 View Post
I was just reading the thread about the guy thats new to RC an having alot of trouble tuning in the cold, an realized, maybe its time for something better...
I agree, that's why I converted everything to brushless.

(Sorry, had to do it. But I actually like where this thread's thought process is going and will be following.)

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Old 03-06-2010, 09:17 AM   #12
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I agree, that's why I converted everything to brushless.

(Sorry, had to do it. But I actually like where this thread's thought process is going and will be following.)

*
Internal combustion engines hasn't change. EPA got into the problem. Smog regulations. EFI started in early 70's with VW's. O2 sensors not needed, 2 stroke motor were not required for smog in the days. Knowing basic internal combustion engine, w/ carburation it's easy. Just understanding the difference in pressure (Vacuum), Carbs are made easy. RC's give you Temp gauges(optimum temp), and sight to see what happening(Smoke), to get optimum performance.

RC's is still in there stone age. And not to have to be a Formula 1 technology to make the sport cheaply for everyone. Really don't need all the gizmos of it.

My opinion!! Go out and have fun!!
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Old 03-06-2010, 09:27 AM   #13
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the sensors and procesors would weigh hardly anything. Fuel pump would be the chalenge.

I would love to see a 4 stroke, if someone could get it to rev high enough. It would last alot longer with piston rings.

I am tired of rebuilding and replacing motors. I am starting to get jealous of the electrics. I thing i might be getting one.
You should be getting 4+ gallons out of the cheapest "sport" engine out there. Things have come a long way. A premium "race" engine can go 6-8gal. with nothing but bearing changes depending on model and how you treat it.

Ringed 2-strokes didn't work out too hot due to our insane RPM.

Ringed 4-strokes don't turn as high and thus, you have to increase displacement to get the power back, which means a physically larger unit and more weight.

Kind of a vicious circle.

As far as an 02 sensor; not needed. Someone posted above, speed density would be the way to go and add an EGT sensor instead.
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Old 03-06-2010, 12:37 PM   #14
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I like were this is going, lots of input . Speed density is a great idea it would be simpler without a O2 sensor, and as far as the 4 stroke idea, it brings 1 phrase to mind, theres no replacement for displacement, And as far as the fuel pump, that would be a good idea for another reason because of the fact that we wouldnt be bound to N/A setups, with a fuel pump you can increase the injector size an lbs/hr to handle turboed or superchared setups. As far as price is concerned, if this idea can get off the ground, it will be exspensive at first, but 1 thing usually drives price down an that would be mass production of the system. A HPI 1/5 buggy would be ideal for this project because of the size an room to add all these compents plus its big enough for a 4 stroke motor anyway. The RPM in a 4 stroke wouldnt be a problem as long is it was a small enough displacement to wind out higher, but if the 4 stroke can produce oodles an oodles of torque then the rpm wouldnt be a problem anyway. The vicous circle comment had a good point, but to break that you just need to have a better power to weight ratio. I may have to post pone this project until the fall though because I know I can get into the electronics and programming classes at the local community college, now I know it wouldn't be any MIT level stuff but hey it would be a start.
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Old 03-06-2010, 01:41 PM   #15
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since you only need to tune ones before the car is on the track, you don't need the system to constantly variate the tune during the motor is running. So how about put all the sensors in and place a LCD to tell the driver which needle to turn how much and its direction.

So when you turn on your ECU, it will first read all the sensors then plug all those values in a really weird formula that calculates how much to adjust every needle by and display that to the user. But here's the problem, every engine has a different mechanical advantage, so that master formula to calculate the needle values would be different for every engine. Furthermore the formula would be different for a brand new engine of the same brand and same model than a used one with a few gallons under its belt.
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