'04 Cafe Sport Dyno Run

[raz]

I think they're saying the port should be connected to the airbox. "Intake pressure" would be the air pressure inside the airbox; "intake vacuum" would be intake in the manifold next to the injectors.

No it's just a bad translation. This is the same text from the P8 manual:

Note that to keep the injector pressure stage steady, the difference between fuel pressure and intake

manifold pressure must also be constant. This is achieved by running a tube between the seating of the

calibrated governor spring and the intake manifold.

And here is your pic from the same manual, which also confirms that. They even use a T and both manifolds.

[raz]

So, anyone have any clue on the range of intake manifold negative pressure? Is it peaking like 0.1 bar or 1 bar or what?

For what it's worth, some synch gauges I looked at ranged to 0.6 bar (9 psi). I recall most of the scale being used but it's not bottoming out, so maybe about 0.5 bar (7 psi) is max. normal negative pressure.

 

Fuel pressure regulator is 3 bar (44 psi) so if we connect that hose we will lower the fuel pressure by up to 17%. If that means we actually get 17% less fuel through the injector in a couple of milliseconds, or if there are more complex maths involved, I have no idea.

 

The problem is if the ECU map is not made for this, and we were lean to begin with, this may be overly lean. If you have means to alter the map, maybe there are something to gain, I'm not sure. It should produce an acc-pump effect I think, based on how my gauges use to react on throttle changes.

 

I will try this whenever the sun comes back. My OEM ECU is way too rich at cruise while it seems perfectly tuned for WOT so it just might happen to be perfect

[Ryland3210]

For what it's worth, some synch gauges I looked at ranged to 0.6 bar (9 psi). I recall most of the scale being used but it's not bottoming out, so maybe about 0.5 bar (7 psi) is max. normal negative pressure.

 

Fuel pressure regulator is 3 bar (44 psi) so if we connect that hose we will lower the fuel pressure by up to 17%. If that means we actually get 17% less fuel through the injector in a couple of milliseconds, or if there are more complex maths involved, I have no idea.

 

The problem is if the ECU map is not made for this, and we were lean to begin with, this may be overly lean. If you have means to alter the map, maybe there are something to gain, I'm not sure. It should produce an acc-pump effect I think, based on how my gauges use to react on throttle changes.

 

I will try this whenever the sun comes back. My OEM ECU is way too rich at cruise while it seems perfectly tuned for WOT so it just might happen to be perfect

 

The " negative pressure" relative to atmospheric for a particular engine depends on many factors. In my high compression 383, at cruise speeds it ran around 16 inches Hg, or -7.9 psi (29.92 inches being standard atmospheric pressure), and 20 at idle. In my 302 boat engine, it runs about 10" Hg at cruise and only 12 at idle. ignition timing, valve timing, compression ratio, RPM, engine load, and other variables all affect the intake manifold vacuum.

 

When decelerating from high RPM with throttles closed, I would not be surprised if vacuum increased to 25 or even higher inches Hg.

 

The effect of pressure on fuel flow rate will closely follow Bernoulli's Principle, so the flow rate will be proportional to the square root of the pressure change. Square root of 1.17=1.082, so it's not as huge a difference in AFR.

 

So connecting the hose to the intake manifold will lean out the mixture somewhat at cruise and much more on closed throttle decels. It should make little difference at WOT unless the air filter and/or airbox itself is significantly restrictive. In that case, the fuel delivery will automatically compensate for the restriction at WOT if the hose is connected to the intake manifold. In my case, with no airbox cover, I expect no measureable difference at WOT, and some extended cruising range.

 

The point on whether the map was done assuming the hose was connected is well taken. Even if the map assumed it was connected, if the dealer or Luigi left the hose off, the result would be a richer mixture under some operating conditions and no change in others. That's on the safe side for them, and they aren't buying our fuel.

[mason]

This is the before and after dyno for my O2 Lemans.

My modificatons include,

1. FBF Open air box

2. FBF carbon slip ons

3. Power commander III

 

FBF crossover and 11.1 pistons to install soon

[mason]

Well I tried to upload it but it's 2.44k

[Guest ratchethack]

I think they're saying the port should be connected to the airbox. "Intake pressure" would be the air pressure inside the airbox; "intake vacuum" would be intake in the manifold next to the injectors.

 

As for how quickly or not the pressure regulator would fail getting the rather substantial pressure fluctuations fed into it, I have no idea. Maybe the addition of a pinhole restrictor a la' the little brass units that come w/ carb stix [mercury manometers, whatever you want to call'em...] would be in order? Easy enough to try it out, but to me

so it's all just theoretical AFAIC.

FWIW, I've tried it for many days on the air canister nipples on the intake spigots, under many conditions of operation, and it makes ZERO perceptible difference. My take is that the ultra tiny (I measured the dia. once and posted on it but too tired now to look it up, but from memory, it's literally a "pinhole") air passages are too restrictive to have any effect.

 

BAA, TJM, & YMMV

[Pierre]

I just had my bike dynoed by John Tavolacci at Cliff's.

From the man himself: http://www.guzzitech.com/JTsRosso-PtII-John_T.html

[raz]

FWIW, I've tried it for many days on the air canister nipples on the intake spigots, under many conditions of operation, and it makes ZERO perceptible difference. My take is that the ultra tiny (I measured the dia. once and posted on it but too tired now to look it up, but from memory, it's literally a "pinhole") air passages are too restrictive to have any efffect.

 

BAA, TJM, & YMMV

That's strange. It really should make SOME difference I would have thought. I trust your words enough to be sure you didn't screw up in any way. But did you try it long enough to see if your mileage changed to the better? I'm pretty sure it could lower the fuel consumption right in the areas you wont notice any downsides of it. But that's just from cabin fever theory of course...

 

The narrow passages, is that in the nipples? Maybe wider ID nipples should be used for this application.

[Guest ratchethack]

The narrow passages, is that in the nipples? Maybe wider ID nipples should be used for this application.

Raz, it popped into my head today that the ID of the nipples is 0.030". I think this is right. A proper experiment would be to bore them out substantially and then give it another go, but I find I'm just not that interested.

 

Then again, since there's no FLOW of air through them when connected to the fuel pressure ambient reference, it shouldn't make much difference -- only in rapid throttle transitions.

 

EDIT: CORRECTION MADE PER POST BELOW!

[raz]

Raz, it popped into my head today that the ID of the nipples is 0.30". I think this is right. A proper experiment would be to bore them out substantially and then give it another go, but I find I'm just not that interested.

Well I pay about US$ 7.50 for a gallon of fuel so better mileage is always welcome. But as I said, cabin fever might be a more proper explanation.

 

0.30" is more than the M6 threaded hole it's fitted to... maybe you mean 0.03" ?

[Guest ratchethack]

Well I pay about US$ 7.50 for a gallon of fuel so better mileage is always welcome. But as I said, cabin fever might be a more proper explanation.

 

0.30" is more than the M6 threaded hole it's fitted to... maybe you mean 0.03" ?

Sorry. 0.030".

[Anders]

My 02 Lemans ran perfect, but after opening up the airbox, I decided to pun on an older serial PCIII. I have mistral pipes, an FBF x-over and modded airbox. Before mapping, it made a healthy 77 bhp, after mapping (and this was at 2600 ft elevation), it made nearly 85 bhp, and was the strongest running guzzi I have ever ridden, it wheelied very easy (roper sloppage plate installed) and got better mileage as well. Louie knows the guzzi's well, and really dialed it in. It still shows a dip, but it was so strong, you never noticed anything but horsepower and torque

 

 

That looks really good.Is that with a K&N filter or stock paper filter?

[Chuck]

 

My 02 Lemans ran perfect, but after opening up the airbox, I decided to pun on an older serial PCIII. I have mistral pipes, an FBF x-over and modded airbox. Before mapping, it made a healthy 77 bhp, after mapping (and this was at 2600 ft elevation), it made nearly 85 bhp, and was the strongest running guzzi I have ever ridden, it wheelied very easy (roper sloppage plate installed) and got better mileage as well. Louie knows the guzzi's well, and really dialed it in. It still shows a dip, but it was so strong, you never noticed anything but horsepower and torque

 

 

That looks really good.Is that with a K&N filter or stock paper filter?

 

Uhh, that thread is 9 years old.

[Anders]

 

 

My 02 Lemans ran perfect, but after opening up the airbox, I decided to pun on an older serial PCIII. I have mistral pipes, an FBF x-over and modded airbox. Before mapping, it made a healthy 77 bhp, after mapping (and this was at 2600 ft elevation), it made nearly 85 bhp, and was the strongest running guzzi I have ever ridden, it wheelied very easy (roper sloppage plate installed) and got better mileage as well. Louie knows the guzzi's well, and really dialed it in. It still shows a dip, but it was so strong, you never noticed anything but horsepower and torque

 

 

That looks really good.Is that with a K&N filter or stock paper filter?

 

Uhh, that thread is 9 years old.

 

He he,yes I know.I did a search and found this thread,and took a real longshot he would remember.Chanses are slim,I know.I'm just trying a bit too hard I guess to get all the information I can get on Stucchi vs Mistral x overs.