Combustion experts: You got some 'splainin' to do

[bobhamlin]

Ordered my Techlusion TFI plug and play last night. I chose it for 2 reasons: price AND I like the analogy of adjusting the pots in a manner resembling fine-tuning a carb's jets. This Nomad is my first FI. If you saw my initial posts, I'm less than enthusiastic about the Nomad's gas tank ("How much gas is usable?") and that cryptic digital gauge ("When is it REALLY empty?")

The 'splainin' part: I'm averaging 40mpg. With fuel management, I should expect a drop in mpg because I will be running less lean. I accept that because the experts say it is so.

However, I thought that the purpose of richening the mixture was to create a better explosion. With a better explosion, shouldn't the piston be slammed downward a bit harder, thereby causing me, ultimately, to roll a little farther for each downstroke? Shouldn't the use of the extra fuel be offset by the extra distance gained? If not, what's the purpose of a better explosion, then?

Now remember--I'm a lay person. Feel free to talk down to me, draw circles in the sand, use hand puppets, etc. Just 'splain real slow and good.

[dkdixie]

Hey Bob, Why not? Worked for me.
My mileage went up from mid 30's to high 30's, even low 40's every now & then after TFI installed. Since adding Chuckster plate, mileage is consistantly 40 to 43. but, that being said, I don't ride in traffic much.
I'm sure one of the experts will jump in and explain it to both of us!

[phenrichs]

Just adding a TFI to a stock bike will not increase your mileage. In fact you may not notice much change at all. It is the adjustment to compensate for modifications that is the greater cause of a change in mpg. If you have aftermarket pipes with little to no back pressure (baffles) and you mod the intake to open it up you are increasing the amount of air that goes through the engine considerably. This means that your engine requires more fuel to create a balance. That doesn't mean that you are using more fuel you are just balancing the mix. Once the mix is balanced the engine can manage itself more effeciently and you may again see little change in mpg. If you are like me however and enjoy the increase in power you will find it hard to keep from twisting the throttle. With mods like this throttle activity has more impact on mpg than it ever did before.

It is also very easy to set it too rich and kill your mpg. I did that. Added the tfi, thought I had it set, but was getting 32mpg. Pulled plugs, black and sooted. I am doing the air cleaner now so I will be readjusting. Most people report little to no change and many report and increase because the bike is running better. If you go wild with performance mods and have to really pour the fuel into it you will likely see a decrease.

It has more to do with the computer (ECU) and the electronics than the actual combustion.

[oledawg]

Originally Posted by bobhamlin

Ordered my Techlusion TFI plug and play last night. I chose it for 2 reasons: price AND I like the analogy of adjusting the pots in a manner resembling fine-tuning a carb's jets. This Nomad is my first FI. If you saw my initial posts, I'm less than enthusiastic about the Nomad's gas tank ("How much gas is usable?") and that cryptic digital gauge ("When is it REALLY empty?")

You've done about as good a job of explaining combustion as anyone can do & in terms that anyone who can read should understand or not be trying to adj. anything in the 1st place. ::)

"Efficiency" is the term most commonly used to describe balanced combustion. ;) Mac has done a great job in explaining it.....many times. jes m2cw

The 'splainin' part: I'm averaging 40mpg. With fuel management, I should expect a drop in mpg because I will be running less lean. I accept that because the experts say it is so.

However, I thought that the purpose of richening the mixture was to create a better explosion. With a better explosion, shouldn't the piston be slammed downward a bit harder, thereby causing me, ultimately, to roll a little farther for each downstroke? Shouldn't the use of the extra fuel be offset by the extra distance gained? If not, what's the purpose of a better explosion, then?

Now remember--I'm a lay person. Feel free to talk down to me, draw circles in the sand, use hand puppets, etc. Just 'splain real slow and good.

[phenrichs]

?

[blowndodge]

Your definition of "better explosion" is a little mis-guided Bob.

The property that pushes down on the piston is expanding heat. The hotter the more power, to a point. That point is pre-ignition. The combustion chamber gets so hot that the mixture fires before the spark has had a chance to ignite it. This is how a diesel engine works. The heat of compression sets off the explosion.

This is bad news for a gas engine.

"better explosion" that you will receive with the TFI is that it will be "cooler" because of the richer mixture. Richer mixtures ward off pre-ignition. Ideally you'll want to set the TFI to the edge of pre-ignition for the grade of gas you plan to run. That's were the "best explosion" takes place.

motors that ping "pre-ignition" actually lose power. Too rich of a mixture loses power as well.

[bobhamlin]

Originally Posted by Blowndodge "Darksider"

Your definition of "better explosion" is a little mis-guided Bob.

The property that pushes down on the piston is expanding heat. The hotter the more power, to a point. That point is pre-ignition. The combustion chamber gets so hot that the mixture fires before the spark has had a chance to ignite it. This is how a diesel engine works. The heat of compression sets off the explosion.

This is bad news for a gas engine.

"better explosion" that you will receive with the TFI is that it will be "cooler" because of the richer mixture. Richer mixtures ward off pre-ignition. Ideally you'll want to set the TFI to the edge of pre-ignition for the grade of gas you plan to run. That's were the "best explosion" takes place.

motors that ping "pre-ignition" actually lose power. Too rich of a mixture loses power as well.

Ahh, Master BD-san,

The fog of ignorance has begun to dissipate. Comprehension forms, albeit slowly, at the periphery of my grasshopper-like consciousness.

I am sure to be a hit at the next dinner party when I share this knowledge with everyone. They shall gaze upon me with awe and wonderment.

[blowndodge]

'thou shalt go forth to thine pilgrimage and all drink from the cup of knowledge'

[roadman]

Blowndodge....you truly are a great one

[blowndodge]

'Thou shalt have no other Blowndodge before me!'

It's always a pleasure to help out you clowns!!!

[Todd]

Originally Posted by Blowndodge "Darksider"

'Thou shalt have no other Blowndodge before me!'

:-/ :-/ :-/ thou might ought to look for some shelter :-/ :-/ :-/

[macmac]

Todd, you got one hell of a spark plug there!

[blowndodge]

YIKES!!!!!!!!!!!

[Todd]

Originally Posted by macmac

Todd, you got one hell of a spark plug there!

Yeah, it's a little hotter than stock........keeps melting a hole in the top of the pistons though

[trosco]

I started thinking about the question and well....it went sort of like this: I am going to put more fuel in per revolution of engine so I should use more fuel??? but if that makes more power shouldn't I be able to (put in less fuel) back off the throttle a bit and still get the same performance??? but am I then back where I was with not enough fuel so I don't actually have the extra power???

Oh wait, gotta go, chicken's loose again and gotta catch'em before he tries to cross the road again.