Measuring squish through the spark plug hole

[Guest ratchethack]

Mike appears to have been on the case for years!

Just thinkin' out loud here. . . .

 

By everything I've read bout Mike's work, I'm sure he understands in great depth what I'm just starting to get a grasp of. However, IMHO Mike's standard approach appears to be one that chases peaks on dyno charts. I have no doubt that most of his customers have made this their Holy Grail.

 

My approach would be from an entirely different angle, since I'm not concerned about power peaks on pieces of paper at all, but rather efficiencies, tractability of the engine, and durability for the long haul. By this I mean that my focus is on real-world torque delivery in the ranges I actually use the torque curve on the road. I don't care at all about the power peak. IMHO real-world tractability on the road has next to NOTHING to do with power peaks on the dyno at WOT. Though I use the entire rev range, I seldom even use WOT, so what the engine does at WOT is nearly entirely irrelevant to my interests. I suspect that most Guzzi riders (certainly not all) may be in the same category, whether they've thought about it or not.

 

At some point, my heads will come off for service. This would be the point where I might want to take advantage of the hard-earned experience of the Pro's and that of non-Pro's alike, and optimize what I've got without opening the usual "peak performance on paper" can-o'-worms. . . . If I can reduce the engine's tendency to ping on 91 RON pump gas, improve mileage, and at the same time get a little broadening and lift of the torque curve anywhere from the bottom on up through the mid-range, without compromising durability, depending on how much I can learn about where I consider the cost/benefit tradeoffs to be, it may be worthy of some investment of time, money & energy while the heads are off.

 

Now of course there is a place where the power-peak chasing approach and the real-world tractability approach might well meet in an area of common ground, where some of the same real-world cylinder head modifications to the stock setup overlap. Among other things, I'm trying to figure out where this "overlap" might be, so's I can best know exactly where I'm going before I start out. I realize I'm speaking in generalities here, 'cause so far, that's just about all I've got.

 

Any more intelligence and experience on this that anyone can contribute is MOST WELCOME!!!

[luhbo]

...

Mike, Hubert, Skeeve

The combustion chamber shape resulting from that head design is not favorable, as shown in the following sketch:

 

 

 

These big pockets let me doubt about the serious work in the factory on the combustion chamber shape. Previous Guzzi heads were not of that design and used a large squish area.

 

 

Ernst,

 

When I compare the pictures above showing these three different pistons, especially the OEM/Guzzi one, and then compare this with this more then rough sketch that you are showing in your post, then I ask myself what your intention was.

 

This sketch is so "rough" that I answer it's already lying! Lying means "2 : to create a false or misleading impression".

 

What you have drawn is so far off of reality that I can not understand what makes you think you may doubt about the competence of the technical/quality staff at Guzzi or every other company that was involved in the development of this bike and engine.

 

Hubert

[Guest ratchethack]

This sketch is so "rough" that I answer it's already lying! Lying means "2 : to create a false or misleading impression".

 

What you have drawn is so far off of reality that I can not understand what makes you think you may doubt about the competence of the technical/quality staff at Guzzi or every other company that was involved in the development of this bike and engine.

 

Hubert

Take it easy, Hubert. He's illustrating a good point with a drawing.

 

He's not claiming to have presented an engineering drawing - nor would I presume any intent to deceive here.

 

IMHO, his point is well made, and as far as I'm concerned, it's well taken.

[luhbo]

No, Ratchet, what is shown on the sketch would mean that these chambers that he has sketched would isolate parts of the mixture and prevent any squish at all.

 

It's not only an idea of him or an attempt to illustrate something hard to see, Motoguzznix establishes this as a fact and then derives from this a right to call the people at Moto Guzzi incompetent. I know that naming Guzzi in general lazy, silly, at least Italian, is common practice for some here and on other forums, but as you know, continuos repetition doesn't make things become true.

 

I take it easy, Ratchet, but a public forum should not be an international Bullshit-Bingo happening. This sketch is so far off that it comes already from the other direction.

 

Hubert

[Skeeve]

 

I'm amazed that these things can get past the EPA emissions Nazis this way?!?!?! <_>

 

Well, something to remember is that DOT/EPA certification is "by type," so Guzzi supplies a representative [blueprinted, naturally!] sample for testing & approval, and then relies upon factory assembly protocols (aka, Luigi ) to keep the rank & file within reasonable tolerances [aka, "shouting distance"] of the type sample...

 

Probably a very good thing that nobody stateside subjects motorcycles to recurring smog tests the way cars are done, or Guzzi would have an even lower presence here than now!

[Skeeve]

I've seen engines with one side of the head "offset" ,if you like, to provide a squish band at one side to promote turbulence.

 

Could this be a possibility?

 

What you're describing is sometimes referred to as a "bathtub" chamber; it's something that Harry Ricardo wrote about some 40 years before Guzzi put the hemi chamber in production for the 1st big block Carcano V-2 and while having some much superior characteristics for a 2v head, isn't available for our favorite V11 bikes. It's what modern Harleys (& Buells) use, & mostly why their big twins went from approximately 30mpg w/ the Shovelhead (hemi chamber) to 50mpg w/ the Evo & later models.

 

Ride on,

[Guest ratchethack]

It's not only an idea of him or an attempt to illustrate something hard to see, Motoguzznix establishes this as a fact and then derives from this a right to call the people at Moto Guzzi incompetent. I know that naming Guzzi in general lazy, silly, at least Italian, is common practice for some here and on other forums, but as you know, continuos repetition doesn't make things become true.

Hubert, I'm sincerely surprised at your reaction here.

 

I don't see anywhere that Ernst has called the people at Moto Guzzi incompetent, nor do I find much of an implication of this. As far as I can tell, he's honestly presenting what he's found. Lying is a bit of a serious charge, don't you think? Again, I don't see any evidence for an intent to deceive here. So far, what he's found fits in well with my own direct experience here -- finding no squish band whatsoever.

 

When I opened this thread, I solicited the input and knowledge of those who've actually had the heads off. Ernst has obviously not only done that, but it also appears that he's put some careful analysis and corrective action behind his observations. This is exactly where I was hoping this thread might lead, and I think it's what many others might be interested in as well. No need to dump on the guy for answering my question by way of sharing what he's learned through direct experience. . . . .

I take it easy, Ratchet, but a public forum should not be an international Bullshit-Bingo happening. This sketch is so far off that it comes already from the other direction.

 

Hubert

I, for one, appreciate Ernst's sincere effort at a quick illustration to make a good point. Do you have any knowledge that the concept he's clearly shown is incorrect?? If so, what direct experience or other evidence is your knowledge based on?

[dlaing]

 

 

 

 

 

I took the illustration to be an exaggeration for illustration purpose.

Certainly some have considered photographs I posted to be misleading.

The accuracy of this scribble probably deserves some explanation and it seems that the explanation is promised when MGnix posts his measurements.

[dlaing]

Just thinkin' out loud here. . . .

By everything I've read bout Mike's work, I'm sure he understands in great depth what I'm just starting to get a grasp of. However, IMHO Mike's standard approach appears to be one that chases peaks on dyno charts. I have no doubt that most of his customers have made this their Holy Grail.

I have a different interpretation of Mike's approach.

A good example is what he did for Al R.

Dual plugging, more durable valves, mild porting, high compression pistons that MAY result in better combustion with POSSIBLY no increase of ping tendency. The porting he does results in better balance between cylinders. (But if you are a firm believer in the MotoMan method of building up the ports to improve velocity, I don't know if he follows that strategy, yet he still get proven results, presumably by removing material)

True he also pursues Land Speed Records, but I think if you want a durable, smooth running engine, I am sure he also has an excellent idea on how to improve on the factory design.

Just my opinion.

Maybe some of his customers have something to say???

I think they may be quiet because when they talk to him he probably goes off into technical babble that is easily mis-quoted if they dare try to repeat it.

[luhbo]

....

 

I, for one, appreciate Ernst's sincere effort at a quick illustration to make a good point. ....

 

 

That's it. It's just an effort to make a good point, regardless whether it's technically correct or not and regardless who pays for it.

 

Anyway, shove it. And let us know when the squish band has bitten.

 

Hubert

[motoguzznix]

Ratchet

 

Here is the sketch with my measurements from the head/piston design:

 

Again, this is a scetch, not an engineering drawing!

There is only 1 mm of possible squish with the original head. When you milll off 1 mm from the head, the squish band will increase to 5.5mm, which makes a noticable difference.

 

Hubert,

 

the engineers at Guzzi aren't holy people. They make faults like everyone of us. You have to take into account that the engineering department at Guzzi worked for many years on a very reduced scale. I remember the Lario design, where the valve train/cam/spring calculations were actually wrong. Together with the poor material quality the heads and cams failed in almost every bike. A development like the Breva/Griso engine/drivetrain would never have been possible at that level of engineering manpower. Only the collaboration with the Aprilia people could create an engine that meets the Euro3 homologation.

 

The V11 design is a good working design, when everything is assembled perfect, which not always occurs at the Guzzi factory. So pinging is a problem on many of these bikes, mine pings, Davids pings an others too. This is what I try to get right on my own engine. Maybe there was a piston design like the MR piston intended for these heads, but not realised in the production due to availability. Who knows?

[Guest ratchethack]

There is only 1 mm of possible squish with the original head. When you milll off 1 mm from the head, the squish band will increase to 5.5mm, which makes a noticable difference.

Thanks again, Ernst. I've transferred your measurements to my own drawing for reference. It appears to be a good basis for analysis when weighing the options.

 

At this point in my understanding of the factory starting point and what is possible to achieve by way of improvements for my own objectives, I like your approach. What you've done is to create a squish band that didn't exist to much of any practical extent, and nearly eliminate the "pocket" that you illustrated. Theoretically, and as I think you're in the process of achieving, this should provide more complete combustion, decrease ping, and raise the CR as you've noted. You said you're only half-way to your objectives here. By all means, keep us well informed on your next steps!!

[luhbo]

....

 

What you've done is to create a squish band that didn't exist to much of any practical extent, and nearly eliminate the "pocket" that you illustrated. ...

 

 

 

Ratchet, come on, are you kidding?

 

There was never any pocket to be eliminated. He just changed the sketch and all was ok.

 

Have you already been completely sucked into this virtual computer/forum/egoshooter world that you think by changing some lines on an austrian piece of paper any real world combustion chambers can be modified?

 

Man, plop your fingers out of your plug holes and get out on the road. This will hopefully cure it!

 

Hubert

[Guest ratchethack]

Ratchet, come on, are you kidding?

 

There was never any pocket to be eliminated. He just changed the sketch and all was ok.

 

Have you already been completely sucked into this virtual computer/forum/egoshooter world that you think by changing some lines on an austrian piece of paper any real world combustion chambers can be modified?

 

Man, plop your fingers out of your plug holes and get out on the road. This will hopefully cure it!

 

Hubert

Hubert! I continue to be amazed - and now I'm awed! What is it with you and Ernst?!?!?!? What is it with you doubting his experience?!?!?!!? What is it with you getting your shorts in a twist over me appreciating Ernst's experience and point of view?!??!??!??!

 

If you have no personal experience or evidence with which to doubt Ernst, WHAT IS YOUR PROBLEM?????????

 

Methinks there's more to this than meets the eye??????

 

What unseen diabolical forces of adversity lurk below the surface here?????????

 

What malevolent demons crouch, hidden in the shadows????????

 

Have I found myself in the midst of some leftover Medieval-era Euro Clan feud???!!

 

Guzzi's are amazing anachronisms, and I find their peculiarities occasionally challenging - and always amusing.

 

But in comparison, the behavior of some posters on this Forum makes Guzzi's appear very understandable. . . . .

[big J]

Haw haw!Coming from someone who'll happily have a 2000 word dig at anyone who disagrees with his point of view,that's priceless.

 

If Hubert has a valid greivance with motoguznix's information,surely they can air their differences and sort it out?

 

I dont like it when people put one another down,but a healthy debate is nothing to be feared,as long as personal insults are not used.Purely from a personal point of view,I prefer the direct approach,call a spade a spade,etc.

 

This stuff is nothing new anyway,engine tuners and scholars of the infernal combustion engine have been "debating" design and manufacture for years.