Fz6 Vs R6 Injection Order

[maur_c@hotmail.com]

The FZ6 has 2 injections every 720 degrees. The wire of the 1 and 3 - 2 and 4 cylinder's injectors is the same. The ECU has only 2 outputs to inject fuel.

The R6 has 4 independent outputs to inject fuel on each cylinder at different time.

Some questions:

1) The differences in power between R6 and FZ6 are due to:

a. Engine compression: 12.4 (2004 R6) and 12.2 (Fz6 2006-..).

b. Firing order: because 2 cylinders are taking air at the same time, so the flow is restricted. On the R6 only 1 cylinder takes air at the same time. That means more air flow and more air mass on the cylinder to compress.

c. Fuel pressure: the fuel pressure is lower when two injectors are working than one injector working at the same time.

2) The Fz6 engine is appropiate for mid range use. Is the injection and firing order an advantage or a drawback on the power and torque curves? Is this the cause of the fall of torque between 6k and 8k RPM?

3) What's the advantage of other more complex injection systems like R1 with valves, and R6 with two injectors?

4) What's the advantage of the O2 sensor installed since 2007?

5) The exaust controlled valve has some advantage?

I think is a nice idea to talk about this topic. You can review the wiring diagramas on the service manual.

Someone know about some book about motorcycle injection systems?


Thanks

[urbanj]

I couldnt find the actual spec but im assuming the firing order is 1,3,4,2.
signals go to the injectors 1-4 and 2-3. my assumption without actually checking is that cylinder 1 and 4 are getting fuel when #1 is on intake and cylinders 2-3 are getting fuel when cylinder 3 in on intake. at high rpms this happens very fast that i doubt there is much puddling of fuel behind the valves when fuel is injected to the cylinder not on its intake stroke.

the extra power would come from the bump in compression, cam profiles, ignition timing (r6 uses premium) and refined fuel injection system.

I would love to know the max advance timing of the r6 vs the fz6

[Fred]

Originally Posted by maur_c@hotmail.com

Some questions:

I'm going answer these one at a time to simplify things. You asked a lot!

1) The differences in power between R6 and FZ6 are due to:

a. Engine compression: 12.4 (2004 R6) and 12.2 (Fz6 2006-..).

Correct. I don't know the numbers, but the R6 does have higher compression.

b. Firing order: because 2 cylinders are taking air at the same time, so the flow is restricted. On the R6 only 1 cylinder takes air at the same time. That means more air flow and more air mass on the cylinder to compress.

Incorrect. The FZ6 has the same firing order. It's an inline four cylinder just like the R6, or for that matter, your Honda Accord. A four is going to have only one cylinder ingesting air at any given time.

c. Fuel pressure: the fuel pressure is lower when two injectors are working than one injector working at the same time.

True, to some extent. With more injectors open, you will see a slightly larger pressure drop in the fuel rail. But it's not a huge factor for several reasons.

1. Yamaha tunes the bike and accounts for this pressure drop.

2. At wide open throttle, which is when the R6 begins to walk away from the FZ6, the injectors are running 80-90% duty cycle. That means that they're open 80-90% of the time. The injection pulses are overlapping at that point, so it doesn't amtter if you've got sequential injection (R6) or alternating batch fire (FZ6).

To get into details, the R6 only has one injector open at a time when the injectors are at or below 25% duty cycle. You can think of that as 1/3 throttle and you'll be pretty close.

The FZ6 has fires the injectors in pairs, and I believe does two squirts per cycle for each pair. Once the FZ6 gets above 50% duty cycle you'll see injector overlap. That's more like 5/8 throttle.

Injector timing is a funny thing. But it's not as critical as people like to believe.

2) The Fz6 engine is appropiate for mid range use. Is the injection and firing order an advantage or a drawback on the power and torque curves? Is this the cause of the fall of torque between 6k and 8k RPM?

Neither. As discussed above, it's not a major factor with regards to horsepower.
The loss of horsepower and torque is due to lower compression and a different camshaft. Yamaha took that horsepower and moved it down lower in the RPM range where you'll use it more often.

3) What's the advantage of other more complex injection systems like R1 with valves, and R6 with two injectors?

Better throttle response. Smoother idle and slightly cleaner exhaust emissions at idle (sequential injection does make a difference at idle and off idle.)

4) What's the advantage of the O2 sensor installed since 2007?

Better fuel mileage and less emissions.

5) The exaust controlled valve has some advantage?

Someone know about some book about motorcycle injection systems?

I'm not sure what the exhaust controlled valve is. Is that an R6 item?

For a good read about fuel injection in general, go here.
MegaSquirt Forums

Fred

[DefyInertia]

Originally Posted by Fred

Incorrect. The FZ6 has the same firing order. It's an inline four cylinder just like the R6, or for that matter, your Honda Accord. A four is going to have only one cylinder ingesting air at any given time.

This confuses me...can you explain a big-bang I4 vs. a screamer I4 then? I'm not an engine guy...

[Hellgate]

On the exhaust valve question. Yamaha created an exhaust "gate", if you will, in the mid 1980's call EXUP. Basically it was a valve that governed the percent of the exhaust pipe that was open and a given throttle setting. EXUP was positioned just past the 4 into 1 point in the header.

The idea was to create a broader power band with for the then new Genises Concept motors, see 1985 Yamaha FZ750, with the five valve cyclinder head.

Our FZ6 does not have an EXUP system.

Oh, BTW, without the FZ750 there would be not R1, R6, R anything.

[urbanj]

Originally Posted by DefyInertia

This confuses me...can you explain a big-bang I4 vs. a screamer I4 then? I'm not an engine guy...

nothing with firing order. most I4's are 1,3,4,2

bore and stroke is different physically between a low reving big bore and i high reving small bore. piston speeds need to be kept in check with high rpms

[dako81]

Originally Posted by DefyInertia

This confuses me...can you explain a big-bang I4 vs. a screamer I4 then? I'm not an engine guy...

x2, i'm pretty sure there is a pretty big differece.

[jsp]

Talking about the exhaust valve, the EXUP (EXhaust Ultimate Power).

I was owner os a FZR 1000 EXUP '91. I didn't take notice of the EXUP valve until the day it jammed and had to be removed.
Then I saw how much it was a valuable item in low and mid rpms.

Only the 1000 cc yamaha engines are equiped with it. It is not a 600 cc engine item.

[DefyInertia]

Originally Posted by urbanj

nothing with firing order. most I4's are 1,3,4,2

bore and stroke is different physically between a low reving big bore and i high reving small bore. piston speeds need to be kept in check with high rpms

I believe you're mistaken.

I'm not talking about displacement. I'm talking about how race teams like the Kawi MotoGP team, using an I4, swap back and forth between a "big-bang" firing order (which I believe is 2 at once, 2 at once) and a "screamer" firing order (which I believe is four in a row).

Someone school me........

[Fred]

Originally Posted by DefyInertia

I'm not talking about displacement. I'm talking about how race teams like the Kawi MotoGP team, using an I4, swap back and forth between a "big-bang" firing order (which I believe is 2 at once, 2 at once) and a "screamer" firing order (which I believe is four in a row).

I'd never heard those terms before your post, so I did some quick googling.

Our engines are screamers, in that they fire one cylinder at a time, and the firings are evenly spaced. I believe that the R6 is the same. Most inline 4's work this way.

A big bang would fire two at a time, as you say. Essentially, you're taking a four cylinder and making it work like a large two cylinder engine. Apparently, racers prefer this setup because it makes the bike feel better, and gives the rear wheel more available traction for cornering. (Not a racer, I just read that after a quick google search.)