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]

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?")

http://s2.images.proboards.com/cool.gif 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. http://s2.images.proboards.com/grin.gif 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]

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 http://s2.images.proboards.com/grin.gif

[blowndodge]

'Thou shalt have no other Blowndodge before me!'

It's always a pleasure to help out you clowns!!! http://s2.images.proboards.com/grin.gif

[Todd]

'Thou shalt have no other Blowndodge before me!'



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

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http://www.moonraker.com.au/techni/lightning.jpg

[macmac]

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

[blowndodge]

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

[Todd]

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 http://s2.images.proboards.com/shocked.gif http://s2.images.proboards.com/shocked.gif http://s2.images.proboards.com/shocked.gif http://s2.images.proboards.com/shocked.gif http://s2.images.proboards.com/shocked.gif

[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.

[blowndodge]

Your forgetting that air is mixed with that fuel trosco. At any given throttle opening your letting in a certain amount of air (opened throttle butterflies). The TFI allows more fuel to be brought into the air to mix at whatever throttle opening you have.

In theory, optimal mileage would be produced at the optimum air/fuel mix ratio. That ratio gives the best "bang" for the buck per cycle.

As Bob asked earlier about pushing down the piston, I feel the need to shed light as he is thinking in the right direction.

To get a stock engine to produce more power you need to add a bigger payload (fuel and air) to the combustion chamber. This larger payload will burn longer and thus driving the piston further down the bore before expending all it's energy.

That's why when I hear reports of who's done what to their Nomad and how much more powerful it is I know if it's physically true or not.

Example: The limiting factors as to why our Nomads are low on power is in the head and injection system. I know some are going to say, "wait!! "exhaust and air intake are it!"

Those are "after the fact" mods that are tailored after the engineers determine how much power the engine will make and design the ports in the head, valve size and lift and duration (amount of time the valve is open) THEN design the exhaust and air intake opening based on that.

You can't add more fuel and air if the head and valve train doesn't support the additional fuel your trying to introduce.

If you look at a Meanie 1600 you'll see a different head design, different cam, larger injectors. This tells you right there that adding an exhaust and intake system to your Nomad is not going to make it haul a$$. It may run a little more freely but thats it.

You need to get a bigger charge in the engine to allow the burn to last longer, thus pushing down the piston further to get power.

There are many other factors like weight of the crankshaft that allows how fast a motor can rev up. Light crankshafts whip up quickly but provide no enertia. Heavy crank engines has lots of "flywheel" enertia. This means that once the crank is spinning it tends to want to continue to spin. Light crankshafts spinning can be stopped more easily by drag placed on the engine.

A Nomad with a lightened crankshaft, fully ported head with bigger valves with more lift and duration with a large injections system WITH a free intake and exhaust system would totally blow by a V2K Vulcan.

Just take a look what HD did with their V-Rod. It's a small V-Twin that hauls A$$. Light weight crank; head design totally different than a Nomads to flow more fuel up to 9K rpms.

With AQMD smog restrictions, HD is going to have to go to this water cooled design with all their bike soon.

Hopefully this explains some of the questions that my earlier answer opened up! http://s2.images.proboards.com/grin.gif

[phenrichs]

That brings up another question BD. Is the cylinder and block the same on the nomad and meanie with just a different head? I wonder if it would be like the older chevy v8's where you could swap heads and boost flow or compression to get some more ponies out of it. The bigger injector is an interesting item as well.

And boy when HD has to go to all liquid cooled you better get in line cause the waiting list for Vulcans is gonna get longer than it already is.

[dogdoc]

mpg DO go down my in city went from 30-32 down to 28-29 not bad but down. Im sure hwy will too. Not sure how some claim they went way up on the hwy. different strokes for diff folks I guess.

[blowndodge]

The ECU is different on a Meanie OP. One of the parameters is that the redline is 6200 instead of 5900 I believe.

[phenrichs]

hhmmmm. Just pondering the ridiculous that's all. you know kind of like the hd guys did when they started with 120 inch engines and leftside belt driven blowers. Just thinking about how much more potential one of these beauties really has.

[blowndodge]

You have to experiment and fail until you hit on something that works.

In my motorcycle drag racing days head porting was part of the "unknown". One year somebody (Byron Hines of V&H) came out with ported heads for his rider's (Terry Vance) honda 750 4 cylinder bike. that bike made so much more horsepower that team dominated racing for 20 years. His "discovery" soon became known amoungst the racing crowd and now head porting and shapes and designs are a common practice. Head porting is the #1 factor in producing high horsepower.

Reading his story he said he was just playing around in the flow room with some old heads and stumbled on it.

[Todd]

mpg DO go down my in city went from 30-32 down to 28-29 not bad but down. Im sure hwy will too. Not sure how some claim they went way up on the hwy. different strokes for diff folks I guess.

Keep playing with your setting Doc until you reach that sweet spot. Mine did the same as far as losing MPGs and on the Custer trip I kept fiddling with it just in small increments at a time....now have it up around the 40mpg avg range WITH the performance benefits.

[phenrichs]

Todd that is exactly what I am doing now. I was getting 32 hwy to Custer. Plugs tell me it was rich.

[caper]

Explosion is result of expanding gases,from an ignition source, a bomb,in gasoline engines? in rifles,Its how you harness the explosion, force a piston down, bullets to accelerate etc. Personally I don't think its the expansion of Heat .Heat is the byproduct!

[reaper]

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 http://s2.images.proboards.com/shocked.gif http://s2.images.proboards.com/shocked.gif http://s2.images.proboards.com/shocked.gif http://s2.images.proboards.com/shocked.gif http://s2.images.proboards.com/shocked.gif
no wonder he needed a TFI

[AlabamaNomadRider]

You guys are way over my head. I just ride em, take em to the expert when it comes to things like what you are talking about.