4v Vs 8v

[Huzo]

My Norge is an '07 4v motor, I've never ridden an 8v, in real unbiased terms, what is the realistic difference between the two with all other things being equal. The main thing I've been led to beleive is that the earlier 4v motor like mine has more torque below 4,000rpm and less in the upper range of revs. What's the real truth without a bias of which engine is "better" ?

[rocker59]

The range where I ride Guzzis is 4000 - 6000 rpm.

In that range, I find the 8v engines feel more powerful, and more willing to rev.

That's not to say they're "better" than a 4v Breva/Norge mill.  Just different, and a little more powerful.

[Huzo]

To use an old fashioned term, would you say "peaky" by comparison ? I know that the obvious answer is to ride one but I'm a bit nervous at what I might find out, I'm a bit scared that I'll get rapt and want one. IMO it's not as good looking as the earlier 4v motor like mine but clearly that's subjective.

[Kev m]

I owned a B11, and I've ridden a Griso 8V.

They are both fine motors and there's a lot to like about them.

The 8V offers "more" but only above about 5500 rpm (comparing stock-to-stock).

Ironically I tended to ride my big block Guzzis more in the 3500-5500 rpm range with only occasional sprints above that.

I liked the relative simplicity of the 2V head - and as such really had no need for more than the 1100 motor.

So "better" to me was always the 1100 motor.

To use an old fashioned term, would you sat "peaky" by comparison ? I know that the obvious answer is to ride one but I'm a bit nervous at what I might find out, I'm a bit scared that I'll get rapt and want one. IMO it's not as good looking as the earlier 4v motor like mine but clearly that's subjective.

I don't know if I'd call it peaky, but the hp does take off from 6-7k rpm...

It makes good power before that (mostly equal to the 2V, but there's a dip in the stock output where it is actually a little lower in the mid 4000 rpm range).

I can't say what YOU would want.

[kirb]

I have a 4V Griso and 8V Stelvio. The Stelvio has a different cam profile to take advantage of the lower end while giving up a little on top.

The 4V is a great motor. It loses steam on the top end, but it's overall feel is fine for where I use it.
The 8V in the Stelvio is a great all around engine. It don't think it misses on the low end and the top end rush is fine. This motor seems to be a better all around engine than the 4V...

Not sure I would be looking at taking the hit on a Norge 4V to upgrade to an 8V. The price isn't worth what is gained.

[Huzo]

No the Norge isn't for sale and never will be, so wasn't looking to change and thats why I won't ride one! I heard what I wanted to hear when Kev said about the trough in the torque curve around 4k. that's what I was told by a geezer in London who really knows.

[Kev m]

No the Norge isn't for sale and never will be, so wasn't looking to change and thats why I won't ride one! I heard what I wanted to hear when Kev said about the trough in the torque curve around 4k. that's what I was told by a geezer in London who really knows.

To be clear the only direct comparison dyno chart I have is HP only. There's a small dip in the HP in that range.

But looking at other 2V and 4V charts it does appear that the 4V motors take a hit in that range in both HP and Torque, while the 2V motor makes more power and torque in that range (even though it ALSO takes a hit in torque).

Still from riding them, I don't think it's that big a difference in feel. Owners of 8V bikes probably just ride in a slightly different rpm range much of the time.

Certainly if you're wringing them out there's no comparison the 8V bikes ARE FASTER there's no way around that.

[Wayne Orwig]

With the 8V, you WILL find the rev limiter.

[pyoungbl]

A roller 8V is also a bit quieter than either flat tappet engine.  Sounds less like a box of rocks in a wheelbarrow.

[Moto]

With the 8V, you WILL find the rev limiter.

You'll find it with the 2V too, if you want.

I've looked at perhaps all the dyno curves as they've come out over time, especially for the Grisos. I also own a Griso 2V and road tested a Griso 8V.

As first released, the 8V did have a pretty bad dip in the curve near 3500 rpm, where it was worse than the 2V. After 5000 rpm the 8V was much stronger.

Later maps from the factory (and from Australia) seem to have cured the dip, so that the 8V is marginally better than the 2V below 5000, and still much stronger above.

It depends on what you want. They're both great engines, I think.

Moto

[canuguzzi]

A good map and good tune makes all the difference. Expecting a transformation from a new map on the 8V Norge would indicate the state of tune wasn't as it should be to start.

The maps do even out the power delivery, there is no snatchiness or parts of the rev range and go flat or even dip, it is rather linear, the more rpms, the more power. Where it might show up is in high speed riding. Coming back into California there are some decent grades that go for quite a while. If you are already in the higher ranges of speed and need more, the 8V Norge just goes.

The same applies to getting up to speed, you can shift early and just run it up, there is no lack of power even from low rpm ranges. There isn't a sense of bogging down, just more rush as you twist the throttle.

The thing with power is that you adjust and compensate for less power, we've all done it. Doesn't matter if it's a car, truck or whatever. However, if you have more power and then get on a bike that has less, you feel that right away.

The 8V loves to rev, no question about that but it doesn't seem to detract from lumbering around when you'd rather glide through forested roads and just enjoy the sounds and sights without constantly revving the engines to move.

In.person, the 4V Norge looks better (IMO) than the 8V but that is cosmetics.

[frans belgium]

I had the big 2V Breva (1100) for 6 years and the 4V Norge for 3 now.
The Breva came strong out of the box.  Pleasant and reliable.
The Norge needed tweeking (new map from Beetle and synch the bodies). 
After that, the Norge ran stronger than the Breva at any rpm, an tangible difference.
Go for the 4V if you can, but there is absolutely nothing wrong with the 2V.

[Huzo]

Yes that's pretty enlightening, with the dyno, because HP= torque x RPM, a drop in torqe at a given RPM value will always result in a corresponding drop in calculated power. But finally, which one "feels" more Guzzi esque ? (please say the 4v)!

[Kev m]

Yesh that's pretty enlightening, with the dyno, because HP= torque x RPM, a drop in torqe at a given RPM value will always result in a corresponding drop in calculated power. But finally, which one "feels" more Guzzie esque ? (please say the 4v)!

It's an issue of scale. You're of course correct that if there's a dip in one there should be in the other.

But the dip on the 1100 chart I'm looking at only amounted to ~5 ft. lbs. (from about 55 back to 50 ft. lbs.) over a 1000 rpm range.

RPM was still increasing over that range, as was hp (from about 33 rwhp to 38 rwhp), just it's not as robust a growth as you would otherwise see, for instance in the next 1000 rpm as torque climbs back toward 55 ft. lbs. the hp climbs from 38 to 53 rwhp.

So the dip is not an actual decrease in hp so much as a decrease in the rate of growth.

The 8V having a larger torque scale torque dip (on the stock curve) goes as far as going flat on hp (no increase) over a small portion of the range.

But yes, a "dip" was the wrong term.

Clear as mud?


As for Guzzi-Ness (Carl-Ness, Lance-Ness - movie reference) I don't think either is more or less or lacking in any way. We're splitting RCHs in feel.

[Cool Runnings]

I have a 4V Griso and 8V Stelvio. The Stelvio has a different cam profile to take advantage of the lower end while giving up a little on top.

The 4V is a great motor. It loses steam on the top end, but it's overall feel is fine for where I use it.
The 8V in the Stelvio is a great all around engine. It don't think it misses on the low end and the top end rush is fine. This motor seems to be a better all around engine than the 4V...

Not sure I would be looking at taking the hit on a Norge 4V to upgrade to an 8V. The price isn't worth what is gained.

The 4V has flat tappets correct?

[beetle]

The 2V had better maps from the factory. The 8V early maps were abysmal. The current map for the Griso has not changed since 2010. It was pretty rubbish too. A well mapped 8V will blow a 2V out of the water. Everywhere. That's the ugly truth.

[ohiorider]

The 2V had better maps from the factory. The 8V early maps were abysmal. The current map for the Griso has not changed since 2010. It was pretty rubbish too. A well mapped 8V will blow a 2V out of the water. Everywhere. That's the ugly truth.

My 2012 8vSE stock map was strong from 3000rpm up.  Now, having not ridden a remapped 8v, I probably don't know what I don't know.  But having owned both the Griso and a 2008 1200 Sport (also stock mapping .... still) seat of the pants dyno tells me the Griso would eat the Sport alive at 3000-5000-7000rpm.  Maybe my Griso was an oddball where everything came together just right from the factory (?)Wonder if Guzzi Steve slipped my bike a shot of speed?

[kirb]

The 4V has flat tappets correct?

Yes, but cams are not in-head. It doesn't suffer from what the 8V flats are suffering from currently (and why you now have rollers).

[beetle]

Wonder if Guzzi Steve slipped my bike a shot of speed?

Steve knows what he is doing. I've lost count of the stories of poorly tuned 8V engines. Poor (or no) PD doesn't help when the bikes sometimes leave the factory with both air bleeds open, TB's not synced, incorrect TPS setting. The same techs were probably good with the 2V. Maybe.

The 8V head had unique characteristics that make it very sensitive to incorrect inlet/exhaust tuning.

The maps in the 2008-2010 Grisos were truly atrocious, and I think this is where the myth of the 2V having better low end torque started.

[Kev m]

The maps in the 2008-2010 Grisos were truly atrocious, and I think this is where the myth of the 2V having better low end torque started.

It wasn't a myth when it was true lol.

I'm drawing my data from early Roper dyno charts, he did an overlay with a 2V and 4V.

[Huzo]

But chaps, aren't we losing site of the KPI's of what sets the value of our Guzzis, and I'm as guilty as anyone. Because realistically the best tuned stock Guzzi in the world would get beaten like a red headed step- son against say, an Aprilia rsv 1000, or something of that ilk. Whether a 2 valve head Guzzi gets flogged by a 4 valve head is probably not the thrust of my question at least. I'd like to know which one "feels" nicer, ( both words chosen carefully). IMO my Guzzi feels muscular because there's no dips or dives in the seat of the pants feel of the acceleration it serves up, certainly not in the same universe as my old GSXR 1100 or MV Agusta, but they had all the soul of a wooden spoon, and my Guzzi (the only one I've ridden), feels " velvety", if that makes sense. So is the 4 valve head Norge as traditional in feel.

[beetle]

Again, your back to tuning. And subjective. Any well mapped, well tuned fuel injected Guzzi should have smooth linear power, yet still have the visceral feel of those big power pulses. Regardless of how many valves it has.

It ends back to this: do you want 110HP or 90HP? Do you want to pull the skin off a custard, or pull down small buildings? Do you want low rev max power, or do you want a roller 8V that can wind out to 9000 RPM? (Yes they can).

[Moto]

But chaps, aren't we losing site of the KPI's of what sets the value of our Guzzis, and I'm as guilty as anyone. Because realistically the best tuned stock Guzzi in the world would get beaten like a red headed step- son against say, an Aprilia rsv 1000, or something of that ilk. Whether a 2 valve head Guzzi gets flogged by a 4 valve head is probably not the thrust of my question at least. I'd like to know which one "feels" nicer, ( both words chosen carefully). IMO my Guzzi feels muscular because there's no dips or dives in the seat of the pants feel of the acceleration it serves up, certainly not in the same universe as my old GSXR 1100 or MV Agusta, but they had all the soul of a wooden spoon, and my Guzzi (the only one I've ridden), feels " velvety", if that makes sense. So is the 4 valve head Norge as traditional in feel.

I'll take a stab at this. If you wonder whether either feels like an old Tonti (Is that what you rode?), the answer is no. A big part
of the feel of those (and of the earlier Ambassador/Eldorado) comes from their enormous flywheels. Velvety is a good word for that feel.

The 8V Griso is very far from that older feel, but the 2V is also pretty far removed: they have very light flywheels. I often thought of installing a larger flywheel in my 2V (though this would take some extra work for the electronic ignition trigger). I finally installed an electronic cruise control on mine to give me back some of the evenness I was missing, but it's just not the same.

Moto

P.S. I bet Kev is confusing this graph of two of Pete's early dyno runs



with this one I made comparing one of his runs with the results of MCN's tests of the 2V and 8V motors (running the original maps):



You can see the dip in the original factory 8V map at 4500 rpm. (Neither Pete's old map nor the original factory 8V map is relevant anymore, though. Beetle and Pete have a smoother map, and so does the factory, I understand. I don't have direct experience with either.)

M.

[canuguzzi]

Since you've done it, what happens between 8000 and 9000? I mean is there something to be gained past the 8500 limit I think you put into the last map? Is that a forbidden zone at which point you should have a well stocked shelf of parts just in case?

[tris]

...
with this one I made comparing one of his runs with the results of MCN's tests of the 2V and 8V motors (running the original maps):



You can see the dip in the original factory 8V map at 4500 rpm. (Neither Pete's old map nor the original factory 8V map is relevant anymore, though. Beetle and Pete have a smoother map, and so does the factory, I understand. I don't have direct experience with either.)

M.

Ignoring the Roperised motor, this seems to say to me that unless you ride with the revs over 5500 there is little to choose between the 4v and the 8V

As I tend to ride my Breva 4V in the same range as Kev does I suspect I'd never see the difference

[molly]

When the first 8V bikes started appearing in the U.K. I owned a 1200 Breva 2v (not Sport but a Norge without fairing) and rode it back to back with the 8V Griso and Stelvio and preferred the Breva each time.  For some reason the 2V motor suited my riding style better, even my local Guzzi dealer who rode each new model back from the factory preferred the 2V.

As we say around these parts. 'There's nowt so queer as folk'.

[ohiorider]

I've been a huge fan of the 1151cc 2v since the day I took delivery of my 1200 Sport almost 6 years ago.  It's a sweet blend of smoothness with some get up and go when called on.  She's a keeper!

[jacksonracingcomau]

When the first 8V bikes started appearing in the U.K. I owned a 1200 Breva 2v (not Sport but a Norge without fairing) and rode it back to back with the 8V Griso and Stelvio and preferred the Breva each time.  For some reason the 2V motor suited my riding style better, even my local Guzzi dealer who rode each new model back from the factory preferred the 2V.

As we say around these parts. 'There's nowt so queer as folk'.

time will determine the better motor, queers or no queers
Pushrod BB stood test of time already, 8V, wait and see, not promising to date but rolllers bring freedom, see
https://www.youtube.com/watch?v=yUwW108ITzw

[molly]

time will determine the better motor, queers or no queers
Pushrod BB stood test of time already, 8V, wait and see, not promising to date but rolllers bring freedom, see
https://www.youtube.com/watch?v=yUwW108ITzw

By the way 'queer' meant 'odd' in more innocent times and I loved the Bay City Rollers as a kid, brilliant.

[Dilliw]

Ignoring the Roperised motor, this seems to say to me that unless you ride with the revs over 5500 there is little to choose between the 4v and the 8V

As I tend to ride my Breva 4V in the same range as Kev does I suspect I'd never see the difference

5500 is easy to get to especially on the Griso.  That's probably why so many people complain about the fuel range of those bikes; they are a workout for the right wrist.