ECU

[Skeeve]

Thanks Skeeve.

But which would perform better, our stock exhaust with its (2) ~one inch outlets, or a crossoverless design with half the restriction, for example hanging four mufflers on our bike, two on each side with no crossover, so you would have (4) ~one inch outlets. (No I am not gonna mount 4 mufflers)

 

Functionally, they should be close to identical, except of course that all those cans = added weight.

 

I am concerned about airflow contamination from one cylinder to the next via the crossover.

I would rather lose a little power if it helped the bike run better.

 

How is it going to help the bike run better? If you want to tune the cylinders separately, you can add a tap to the individual headers and take your samples upstream from the crossover. Doesn't much matter, tho', since the Guzzi ECU slaves the 2nd cylinder to the first, as I understand it.

 

Enzo's design is so free flowing that I don't think he is getting much cross talk between the cylinders.

Franks' has no crossover, and his mufflers may be too constricting, but he has no crosstalk issues(except on the intake side, but he will be getting pod filters)

If Frank added a crossover, the mufflers would not be too constricting, but he might get cross talk issues.

Sorry, I made up the term "cross talk" is there a better term?

Or is the issue just overblown in my head and I should use a crossover.

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I think you're making way too much of the issue. Reasons for getting rid of the crossover entirely would be for cosmetic or weight savings issues; I don't think that you can expect to make the bike run better [except for say, one specific throttle setting like WFO] by eliminating the crossover. Look at the evolution of Guzzi exhausts: they started with individual header/muffler pairs, added a balance tube abaft the engine, then an x-over, then kept the x-over and added another balance tube at the *front* of the engine. Now Enzo's pipes and those on the Griso are moving that x-over [in the form of a 2->1 junction] closer to the front of the engine where the balance tube was previously added. This is all in getting greater & more consistent performance out of this old lump.

 

As far as how this applies to the ECU, I assume you're worried about mixing the gases from the respective cylinders & thereby throwing off the lamda sensor(s), but since the response delay [ie, effective sampling rate] is greater than the firing frequency, there is always a mix of exhaust gases being sampled, so you can't get what you want. But if you try, sometimes you'll get what you need, ie: the sample obtained from mounting a lambda sensor in the exhaust plenum [the stock item is more than a x-over, really] is good enough to give you feedback that will keep the engine "close" to optimum.

 

But that's just MNSHO; I'm not an expert, so you can ignore me if you want.

[callison]

For Moto:

 

What do you mean, "even"?

What, you mean you're uneven Nah, I'm just going to defer to your obviously greater expertise and technical prowess. The "even" just means I'm not speaking for you in case your opinion were to be different.

 

If this thread runs long enough (it must be well on its way to record length already), we might all come to a common concensus on a number of points, but I suspect that Moto's level of involvment at the pure nitty gritty level will determine the threshold. All numbers and hardware configurations aside, the guy who actually does this kind of work on a dyno is going to provide the best input, that appears to be Moto. He's also extraordinarily good at picking apart statements for misinformation (something that I seem to have more than my share of), so I'm going to just sit back and follow the thread and see where it can take me in the understanding of all of this stuff.

[Guest John T]

Moto,

 

You go by the name DCAPITO on the aprilia forum correct??

[Guest Jeff in Ohio]

so I'm going to just sit back and follow the thread and see where it can take me in the understanding of all of this stuff.

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yep. basically this whole thread reached the level of mental masturbation quite sometime ago for me too. bottom line is, my bike runs pretty damn good with a tuning linked PCIII as a do a lot of others. This whole open vs closed, etc is really getting down to splitting hairs at this point. Especially dragging in the Aprilia that runs a diferent ECU/system than the Guzzi anyway. Could better results be achieved by directly mapping using Tuneboy, FIM, Cliffs, or Technoreseachs new tool? Probably. But HOW much better, 2, 2, 3 HP maybe? I don't know, don't really care because my bike runs like a scalded dog and gets 44mpg. Do I wanna pay somebody $500-$1,000 PLUS to slave over my ECU for hours on end looking for that last drop of power?? Errrr, no. Bike runs great as is and I only have $300 in the PCIII and tuning link. Anyway you slice it, it STILL is better than a carb.......

[Guest Jeff in Ohio]

Moto,

 

You go by the name DCAPITO on the aprilia forum correct??

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ding ding sing, the light just went off!! Moto is the dude from moto-lab.com that charges $816-$2,800 to set up all the throttle positions on a powercommander (according to his website pricing). No offense, because you (moto) obviously know what you are doing, but ain't no way I'd pay that much to set up my FI system. I'm not made of money, but that's just me......

[moto]

I wrote: something about adding ram air.

Carl wrote: "Can a Dyno effectively optimise for ram air induction?"

Moto asked: "Are we talking about an existing system, or adding one?"

We are talking about adding one.I know, all the experts say you don't get any gain until well over 100MPH...blah, bhah, blah...Regardless, I like the idea. I think it could help especially when fighting headwinds at high speeds....not an uncommon practice in the South Western US. Also, it would act as a cold air induction system. From what I understand some dynos act as wind tunnels and most do not.

I have not yet seen a dyno that acts as a wind tunnel. I suppose one could put a dyno in a windtunnel and then test with airspeed below, at and above roadspeed.

But all, must have fans to keep the engine from overheating, or at least slow down the overheating.

Yes, but you would be surprised at what some dyno facilities have, or don't have, I should say.

 

If you didn't have a wind tunnel handy, you could put pressure transducers in your airbox and record with a datalogger. You could then try to duplicate various airbox pressures, up to the max of what the datalogger recorded, on the dyno. This is very difficult to do, as a major amount of CFM are required. A magazine tried doing it a while back and found that they were not able to find a suitable fan. Just because they couldn't do it doesn't mean it can't be done, but you get the idea that it's nontrivial. What they did find to sort of work was a huge industrial compressor with a massive hose. With this thing, they were able to create enough pressure for just long enough to do a run. In the case where the motorcycle had two inlet snorkels, they had to block one so the pressure wouldn't leak out. I think they were just trying to show how much more these engines put out at speed, and I don't think this type arrangement would be suitable for development work, as controlling the pressure would be too difficult. Ideally, you would test at all combinations of throttle position, rpm and airbox pressure the engine might encounter. Then we arrive at the next problem, which is that there isn't any way to access (so far) the air pressure correction in the ECU. If we were lucky, we might find that there is no error, and that the ECU corrects just fine. If there were errors, we could tailor the fuel delivery to the most common or most important (as deternined by datalogger traces) airbox pressure for a given throttle position/rpm. Or we could average the error over the given throttle position/rpm so as to loose the least power at either end of the pressure range. Or some combination of these two approaches. Maybe we could construct a lying box that intercepted the signal from the ECU's airbox pressure transducer and tweaked it so the ECU would think there was a pressure that happened to make it correct exactly the way we wanted. To start, in the case of the Guzzi, I would just see that there is a pressure transducer in the airbox stock, see whether it has the range needed to provide the appropriate signal to the ECU, and lastly see if the ECU has enough range built in to respond to the signal . If only wideband sensors didn't have the problems they do, this, with the development of proper targets, would be a perfect application for a closed loop ECU.

[callison]

Maybe we could construct a lying box that intercepted the signal from the ECU's airbox pressure transducer and tweaked it so the ECU would think there was a pressure that happened to make it correct exactly the way we wanted. To start, in the case of the Guzzi, I would just see that there is a pressure transducer in the airbox stock, see whether it has the range needed to provide the appropriate signal to the ECU, and lastly see if the ECU has enough range built in to respond to the signal.

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Just for a first pass, you could hook up a TwinMax - one input in the airbox and one at ambient in a non-perturbed area and tap the meter circuit for the differential voltage and use that somehow with the ECU. I would think the output of the differential pressure sensor is far more linear than the output of an O2 sensor, but if you had a linearized O2 output from a WBO unit, you could conceivably combine the two signals with an op amp and hook the inputs up differentially, additively or subtractively with a gain compensation on one or either leg to provide some interesting output schemes to the ECU.

 

This is getting really weird...

[dlaing]

This is getting really weird...

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Speaking of which, I think there is a market for an onboard Twin-Max, or equivalent.

Or at least a warning light that would tell you, time to synch the TBs.

Does anyone make a rugged electronic airpressure sensor with two tubes coming out so one could measure the difference?

[callison]

Why not go whole hog? A little servo motor hooked to the throttle body linkage ajustment wheel actively kept centered by the TwinMax output. All time real time synchronization.

[dlaing]

Why not go whole hog? A little servo motor hooked to the throttle body linkage ajustment wheel actively kept centered by the TwinMax output. All time real time synchronization. 

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But that would be CLOSED LOOP!

We cannot have that!

[callison]

But that would be CLOSED LOOP!

We cannot have that!

41846[/snapback]

 

No big deal. No map...

[al_roethlisberger]

I like traffic lights....

 

I like traffic lights.....

 

I like traffic lights......

 

 

... but only when they're green.

 

 

 

 

 

 

 

 

He likes traffic lights....

 

 

 

 

[Skeeve]

Why not go whole hog? A little servo motor hooked to the throttle body linkage ajustment wheel actively kept centered by the TwinMax output. All time real time synchronization. 

41843[/snapback]

 

[gazes into crystal ball]

I'm getting a picture... where you try twisting the throttle and your Guzzi actively shuts it on you every time, ripping the palm off your glove & breaking your wrist in the process!

[/crystal ball]

 

Of course, this system would work fine for BMW riders, since their boxer motors have simultaneous induction, but IT... CAN'T... WOOOOOORK! [/young Frankenstein] on a 90deg V engine, since there will always be a difference in the intake vacuum... if the engine is running properly!

 

But thanks for playing! Johny River, what do we have for our departing guests?

[callison]

[gazes into crystal ball]

I'm getting a picture... where you try twisting the throttle and your Guzzi actively shuts it on you every time, ripping the palm off your glove & breaking your wrist in the process!

[/crystal ball]

 

Of course, this system would work fine for BMW riders, since their boxer motors have simultaneous induction, but IT... CAN'T... WOOOOOORK! [/young Frankenstein] on a 90deg V engine, since there will always be a difference in the intake vacuum... if the engine is running properly!

 

But thanks for playing! Johny River, what do we have for our departing guests?

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Sorry Skeeve, but you've misinterpreted that one. The throttle body linkage adjusment wheel is the little white plastic thing on the threaded rod part of the linkage between the two throttle bodies. You can make the bike run really bad (or good) playing with it, but you can't make it rip the throttle from your hands. It's never perfectly in sync at all throttle positions either, so it actually might be of benefit to mke it actively adjust itself. Mechanically, it would be a bit of a problem since it moves with the linkage.

 

And the intake vacuum? Well, you wouldn't want rapid changes here, so the vacuum ports would go through some pretty small orifices on their way to the transducer. The time constant would likely be in minutes. A lot of carb balance units, including the TwinMax'es, ship with these reducers specifically to handle the offset power pulses in the vacuum areas being measured.

[dlaing]

He likes traffic lights....

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You are just peeved because Carl and I together have more than half as many posts as you, and if you don't keep up with the posting the two of us together, may get MORE posts than you.

 

PS didn't you post a few years ago, something about an onboard TwinMax?