6th Gen Guhl reflash discussion

California tests emissions and noise levels at 5000 RPMs. Or maybe just noise... I can't remember but one of the bigger laws states at different RPMs including 3K and 5K. You probably could get an optimal crossover lower down, but Honda wants to be well clear of the standards so they choke the shit out of their engines at 5000RPM.

I wonder if there's an advantage to VTEC without the interest of emissions standards compliance.

 

If I am not mistaken, Honda claimed that the VTEC boosts low end torque AND helps meet emissions. Don was interested in playing around with it to see what he could make it do for us.

 

Only opening one intake valve fully, creates a swirl in the combustion chamber. This swirl effect promotes a faster and more complete burn. This faster and more complete burn in turn makes slightly more torque, while leaving less unburnt hydrocarbons, aka more low end torque while helping to meet emissions.

The only problem is, eventually at a certain rpm, that single valve opening starts to restrict air flow. Determining that certain RPM where the benefits of single valve swirl effect match the benefits of two valve flow is the tricky part.

Well it's not that tricky. Simply disengage the VTEC solenoid and tune the engine from idle to redline as a two valve. Then lock the solenoid into VTEC and tune as a four valve from idle to redline. Where ever the two HP curve intersect is the optimal VTEC crossover point. Nothing new, the Honda automotive world has been doing this for 20 years or so. Modern system actually have a variable engagement point that varies the rpm with throttle position. No need for engaging VTEC when you are just cruising at light throttle. Then roll into the throttle to accelerate and you get the extra two valves.

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The blue line represents the HP curve of the engine running on two valves. The red line represents the HP curve of the engine running on all four valves. The green dot is the optimal rpm for crossover.

This picture is of traditional automotive 3 lobe VTEC and not 2 valve/ 4 valve "hyper vtec", so the differences in the low end would be less dramatic, but the same principle applies.

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I understand all of this. I've helped drag racing friends with their high lift cams that run like shit at idle and all that. Thanks for the well stated explanation and pictures, though.

I wasn't clear in my short statement. I was musing, from a purely practical view, about what could be done with these bikes. Honda are notorious for engaging the VTEC in the cars at very high (for a car) RPM and tuning the bottom end entirely for emissions and fuel consumption, and it got me thinking about this context. The ECU flash specifically on a VTEC VFR. I just really think the concept of being able to experiment with the crossover point is cool, and wonder whether they really do tune for any performance boost down low or if it is entirely toward lowering emissions for tests, or what the balance is.

I was also of the understanding that the VTEC point was entirely an oil pressure driven thing, and didn't realize you could adjust the actuation point. Which I think is cool in and of itself.

The musing is for no good purpose, I don't own a VTEC, but I would still want to know if Guhl came up with anything purely for curiosity's sake.

I was the kid who took his toys apart to see how they were made. Never outgrew it.

 

Found this excerpt from MOTORCYCLIST, about the 2002 when it first came out. While not the 2006-2009 Don needs to do the reflash, I know that what plagues the these years carried over from the original. Seems much of what we complain about today was known back then- motorcyclist just writes it better

"If the VFR's chassis improvements mark two steps forward, the revamped engine is surely a clip-clop backward. Although architecturally the same as the outgoing powerplant, the new one comes with new heads with a version of Honda's VTEC, a variable-valve scheme that keeps two of the four valves in each combustion chamber closed below 7000 rpm. Honda's use of the "revolutionary" system is ostensibly to bolster low-end torque without sacrificing high-rpm power-an admirable goal. But overlay the dyno graphs of new and old VFR800s and you'll see instead that the new bike has a marked flat spot between 5000 and 7000 rpm. When the VTEC opens the other eight valves, the torque curve shoots up, gaining 5 foot-pounds in 500 rpm. So rather than fulfilling the promise of a beefy, two-valve-per-jug torque curve, VTEC strangles the engine in the midrange and provides a cynical little hit at 7000 rpm to make the engine feel lively. We'd be happy to excuse the additional weight (some of which was countered by the move from gears to chains in the cam drive, at the expense of a genuine acoustical treat) and complexity if the '02 engine were more powerful at any place in the rev range. But it's not, and we don't.
Why would Honda go to so much trouble to, at best, match the peak numbers from the previous engine? Well, the company makes a big stink out of the engine not stinking, that it meets California's '08 emission rules right now. This squeaky-clean engine is made possible by a new, more dense catalyst (for all states, not just California), a revised fuel-injection scheme with Honda's new 12-orifice injectors, iridium-tipped spark plugs fired by cap-style coils, an air-injection system and VTEC. You don't pollute much if the engine is run extremely lean, and the swirl effect VTEC provides-by ingesting air through one of the two intake valves per cylinder, the mixture circles the bowl before it's fired off-permits more reliable combustion at very lean mixtures. The increased cooling capacity (33 percent for the oil, 7 percent for coolant) better rejects the BTUs from this hotter-running engine. And be warned, it does: On a 62-degree day, the engine would top 220 degrees in stop-and-go traffic. Imagine that in Phoenix in July. Here's the deal, though; as enthusiasts, we're less concerned with meeting future smog regulations than having fun now, particularly in light of the fact that modern, catalyst-equipped bikes are already quite eco-friendly. We suspect Power Commanders and dohickeys to work around the VTEC nonsense will be popular aftermarket items for the VFR."

 

That's a pretty good explanation of how lean burn and hyper vtec works together.

I would be really interested to see how much the 5000-7000 flat spot is attributed to lean burn tuning and how much is a limit of the 2 valves cfm flow.

I can tell you that, after richening up the mid range and adding some timing, the sixth gens pull like a freight train through the mid range. But I am curious, if it could get better by opening all four valves a tad earlier, say 6000 or maybe even 5500. Highway cruising could get annoying though.

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I know you are a shill for RapidBike,and that's cool, but the overall package just isn't that great. I've done my due diligence, checked out the software, spent hours discussing the product and it's shortcomings with a group that are one of the preminent dyno manufacturers and race tuners in the United States. How many top level championships has your RapidBike guy won with his tuning? I fully understand why goinphaster wouldn't consider your "go to" product. Your opinions are nothing without dyno runs to confirm your claims. My guess is that you really don't want to know the truth.

 

I'm sorry norcalboy, but you don't have a clue what you are talking about. You have not used rapid bike or tuned ignition mapping. You are only taking a mechanic who is not properly trained's opinion on hardware that he isn't familiar with.

Not very many people are too familiar with rapid bike in the US, as power commander is the go to, but the fact is, the sixth gen has extremely mild ignition mapping and it benefits greatly from ignition tuning, this isn't possible with power commander, but it is possible with rapid bike and hopefully soon with guhl as well.

Spend sometime on the Ducati forums, do some research and you will see just how good rapid bike actually works.


http://ducati1299.com/showthread.php?t=19084


Here are some dynos of termi slip ons and a termi ECU flash versus termi slip ons and rapid bike racing.

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So I was doing some random looking around at some things and noticed that the 8th gen ECU has the same connectors as the 2006-2009 6th gen ECU. It makes me wonder if Don can strip some code from the 8th gen ECU and input it into the 6th gen- like the quick shift feature, and maybe traction control... I know TC might be a stretch, but it may really depend what I find in my hunt for an 8th gen wiring diagram....

 

Traction control would probably need an abs model.

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Bump. I'm still very interested in a Don Guhl reflash.

 

Would like his software and buy the map(s) to install. Something similar to what the Buellsters use:

https://play.google.com/store/apps/details?id=org.ecmdroid&hl=en

 

I'm still curious but less interested at this point. I ended up going with a Rapid Bike EVO and for all intents and purposes, it seems to fit the bill. My main goal was to help improve throttle response and have the ability to change items on the bike without having to worry about going to a Dyno-tuner any time I did. Since the RB EVO uses the O2 sensors, it's basically "auto tuning" while I ride, at least that's how it was explained to me. From the first time I rode it after I installed it, the bike was almost as I was hoping it to be. Now that I've ridden it a few more times it seems to be getting better with each ride.

Compared to a stock map PCV and a stock map RB EVO, the latter seemed to perform much better right out of the box. As mentioned above, seems to be getting a little better with each ride. I'm sure if I opened the software and made tweaks to the settings, I could get even better gains in some areas but to not have to open up a computer and tweak a bunch of settings, I'm really impressed with what I got. I'm also sure that if I was so inclined, I could have bought the RB Racing model and even went a bit further with it like Candyred but that's not really my intention with my 6 Gen.

 

Me too. Apologies, work has gotten in the way of play (The Navy is a cruel mistress like that...). Ill reengage tomorrow.

 

Like I've said before if it wasn't a 1300 mile ride I would definitely volunteer my bike. In regards to changes in vtec engagement/disengagement I think its a great idea but is there more adjustability to it then just a set rpm point? What I'm getting at is there have been occasions where I've cruise right around the vtec engagement and its thoroughly annoying when its in and out of vtec and from my experience in stock form it occurs at a fixed rpm point regardless of throttle position. If the engagement was lowered to 5000 or 5500 would it be possible to prevent engagement until a given throttle opening is reached like say 75%? At 70 mph I am running right at 5000 rpms and while it would be nice to have all 4 valves in operation I think the constant cycling in and out of vtec would be extremely annoying and have a drastic effect on fuel economy. Just my 2 cents.

 

A more intelligent variable engagement point would be great, so you could cruise at over 100 out of vtec, but have vtec engage when you roll the throttle open at over say 5000 or what ever the most efficient crossover happens to be for that gear/speed/throttle/rpm combination. I don't thing the factory ecu is smart enough for that, but if it is, that would be awesome. I am not a fan of the current 6400/6100 rpm window, as it makes tuning a bitch, so even a flash to set an on/off engagement at a set rpm of say 5500 would be great.

 

Or at a certain throttle position? Maybe that way you could raise or lower the engagement point.

 

Definitely, like modern day i-VTEC
But tuning that would be very envolved

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