Chamber Grooves - what do you guys think?

[gas]

I like to think of the old "room full of basketballs" analogy.

How 'bout a bit of psychology?
Have any here, after seeing a positive result from 'whatever' (flow testing may come to mind), and remarked, "gee, would not EVER have thot that would have worked!" If the facts, or the correct solution were ALWAYS apparent, we would ALL (funds notwithstanding) be competing at the same speed.

Reminds me of children, when they won't eat a particular food. Why? They don't like it. How can they not like 'it' when they haven't even tried it first? Because, the decision was made beforehand, the mind is CLOSED! Will/does it work? :shrug: My mind is OPEN. That means I am NOT blindly stating it will... or that it won't. FFT.

[kdrolt]

I like to think of the old "room full of basketballs" analogy .

You've got a big room full of bouncing basketballs ( just like a cylinder full of molecules when the intake valve goes shut)

You shrink the room and what happens ? The motion of the basketballs becomes faster ,more intense, and most certainly more chaotic.

That's exactly what happens when pressure rises, in a container, in a UNIFORMLY distributed manner. That's not what happens between two squish surfaces, with an adjacent chamber volume.

Now would cutting grooves in the walls affect the flight of the basketballs ? Probably so ! Would it do so in a predictable ,planned fashion so that the course of the wild bouncing balls can be "steered" ? HIGHLY DOUBTFUL !

You skipped two important items.

Let the room be the combustion chamber. Let the shrinking walls be the piston crown and the roof of the head chamber.

What happens when the piston approaches, or reached, TDC? Specifically, what happens to the basketballs in the squish region?

Because the volume between the "walls" has shrunk severely, then the local pressure, and density, between the walls must increase significantly (via conservation of stuff). Does the stuff stay there, or will it move out of the squish region?

The universal answer is that the stuff between the wals does, in fact, move in a manner to seek a lower pressure, so the squish volume convects (flows) into the the chamber. The pressure gradient drives the flow in a preferred direction. So the pressure in the whole chamber is not uniform (that's the 1st item you missed in your room analogy) while the piston rises to TDC. And the direction of the flow out of the squish region is one form of steering, it's just not very uniform.

So to conclude the argument, why is it so hard to imagine that the steering be accomplished in a channel so that the plane-plane squish region has an escape path into a channel, a channel that happens to be directed twds the spark plug? That's the 2nd item you missed.

There is always some level of chaotic molecule motion in the cylinder (it's called pressure in a macroscopic sense), but when you have an imbalance of pressure you get a flow that attempts to equalize the pressure. In air we call it weather, where high pressure will induce flow (wind) to low pressure. That's why the self-descriptive squish region works --- it jets a planar (flat) slug of mixture back into the chamber which in turn speeds the burn (once ignited).

The notion of using a channel cut into the squish region merely helps direct a greater percent of the flow stream twds the spark plug rather than just thrusting the flow into the chamber in a less controlled way.

[putztastics]

yeah

now combine this with square tube headers and a high mileage carburetor and we're getting somewhere

[joe]

I wonder if I'm making a mistake responding to this

Yeah the basketballs were a little simplistic compared to a chamber and cylinder , but I was hoping this slight trespass might be allowed in order to help people visualize.

Because the volume between the "walls" has shrunk severely, then the local pressure, and density, between the walls must increase significantly (via conservation of stuff). Does the stuff stay there, or will it move out of the squish region?

The universal answer is that the stuff between the wals does, in fact, move in a manner to seek a lower pressure, so the squish volume convects (flows) into the the chamber. The pressure gradient drives the flow in a preferred direction. So the pressure in the whole chamber is not uniform (that's the 1st item you missed in your room analogy) while the piston rises to TDC. And the direction of the flow out of the squish region is one form of steering, it's just not very uniform.

The stuff moves outta the squish region by way of velocity overwhelming a HIGHER pressure in the chamber . When the piston makes a close approach to the head the velocity between the head of piston and quench area can go supersonic ,at which point it is impossible for sonic waves to pass back into the quench.

The notion of using a channel cut into the squish region merely helps direct a greater percent of the flow stream twds the spark plug rather than just thrusting the flow into the chamber in a less controlled way.

Do we want to aim it at the plug ?

I'm not close minded I have been grinding chambers today in a way that I had never done before , in an attempt to help improve wet flow characteristics but I ground a groove part way AROUND the plug to stop any fuel deposits from collecting there !
The approach I'm using is modelled after a chamber mod I have seen that made best power with only 29* of total timing which means things are more efficient in the chamber and less negative torque has to be undone.

I'll just stick with what I'm doing for the time being and you try that "jet" piston and get back to me when you figure out what is being accomplished.

[kdrolt]

I wonder if I'm making a mistake responding to this

Maybe.

The stuff moves outta the squish region by way of velocity overwhelming a HIGHER pressure in the chamber .

Anything wrong, from an engineering or physics viewpoint, with that statement?

Velocity doesn't overwhelm a higher pressure in the chamber (where the pressure isn't greater, btw), UNLESS the initial swirl/tumble of the mixture has enough momentum to temporarily overcome the adverse pressure gradient. And if that really happened, Ricardo would have been wrongs YEARS ago.

The local pressure increase in the chamber is less than it is in the quench region (between the squish lands) because the change in (swept) volume from piston movement is much less for the chamber than for the squish. THINK about it and you'll get it.

That's the whole point of the squish region -- to squish the mixture from between the lands and force it (in a very turbulent fashion) into the chamber.

When the piston makes a close approach to the head the velocity between the head of piston and quench area can go supersonic ,at which point it is impossible for sonic waves to pass back into the quench.

The speed of sound in air is around 340 m/s (or 1100 ft/sec). The speed of the piston near TDC, the approach you were mentioning, is much smaller than that and it's approaching zero because the crank throw is nearly at it's own top-center, so the translational velocity imparted to the piston is also zero. A very simple kinematic model for the crank, connecting rod, piston, and a known rpm input shows that. So your wrong about the speeds involved, and the notion of sonic waves not being able to pass back into quench runs afoul of what I learned in graduate school studying acoustics.... and it's nonsense relative to this discussion.

....Do we want to aim it at the plug ?

I don't WANT to do anything... but the guy that proposed the idea, by my arguments in this thread, probably thought it was a good idea.

And IIRC there are other threads on this forum, elsewhere that discuss using shapes on the piston crown of HD engines to do exactly the same thing for exactly the same reason. How useful are they changes, and at what speeds are they useful? Street or track use? I have no idea, nor have I searched through the SAE archives to see if the original work is published.

I'm not close minded ....... I'll just stick with what I'm doing for the time being and you try that "jet" piston and get back to me when you figure out what is being accomplished.

Ummm the jet (my words) were the result of a groove in the head, not in the piston. You probably forgot that. And this was a tech discussion but you're now turning it into "dismissal" for me, and self-importance for you. I've seen that before and it's not a good strategy. I think you did make a mistake responding to this thread.

As far as figuring it out, I think I already did, though you didn't get it on the 2nd time around so I don't think another pass at explaining it will help you. I agree that you should stick to what you are doing.

[joe]

Anything wrong, from an engineering or physics viewpoint, with that statement?

there may be ,but if there is it won't help explain why the higher velocity gasses between the piston head and the quench travel into the chamber .

If the area between the quench and the piston head is smaller , then the velocity of the gasses traveling out of it must be greater . Velocity and pressure are inversely realated .

Are they not at a higher velocity ? Are you telling me that the gasses which move from the quench to the chamber travel more slowly than the gasses in the chamber ?

The speed of sound in air is around 340 m/s (or 11,000 ft/sec). The speed of the piston near TDC, the approach you were mentioning, is much smaller than that and it's approaching zero because the crank throw is nearly at it's own top-center, so

Temperature is also involved , the temperature rises with the upward motion of the piston and is additive toward the velocity of the gasses generally .

and the notion of sonic waves not being able to pass back into quench runs

SUPERsonic is what I said , and that means there's a ratchet involved , molecules get a one way ticket.

And this was a tech discussion but you're now turning it into "dismissal" for me, and self-importance for you. I've seen that

OH that's rich ! I'M THE SUPERIOR ONE ! Let's see .

what I learned in graduate school studying acoustics....

There is always some level of chaotic molecule motion in the cylinder (it's called pressure in a macroscopic sense)

In air we call it weather, where high pressure will induce flow (wind) to low pressure.

Lets think of some practical examples .
Years ago the jordans fielded a top alky funny car with a boss 429 based power plant (gary scelzi drove it) . This machine with a roots blower ,an old style manifold (all this means POOR cyl to cyl fuel distribution) LOTSA boost and METHANOL made best power with only 19 ! degrees of ignition advance !! It might have made even more power with less ,but the tuner was afraid to try !

Now lets cut thru the chatter I've given you a very good example of a very efficient working chamber , you point me at an empirical example which will undo the one I've mentioned, with your mans technology.

[kdrolt]

there may be ,but if there is it won't help explain why the higher velocity gasses between the piston head and the quench travel into the chamber .

If the area between the quench and the piston head is smaller , then the velocity of the gasses traveling out of it must be greater . Velocity and pressure are inversely realated .

The pressure in the squish region is higher (otherwise the chamber would evacuate itself into the squish!). The pressure in the chamber (which has a much larger volume, proven if you do the math) is lower. The pressure difference between them accelerates the mixture from the squish into the chamber. So the velocity is smaller in the squish region and increases as it reaches the squish-to-chamber fictional wall (via acceleration). It forms a planar jet. Pressure and velocity are inversely related in EACH control volume, not across both of them (squish, chamber).

Temperature is also involved , the temperature rises with the upward motion of the piston and is additive toward the velocity of the gasses generally .

Yes, I know. But thanks for that reminder.

SUPERsonic is what I said , and that means there's a ratchet involved , molecules get a one way ticket.

Supersonic means shock wave; it means travelling at a speed greater than the linear acoustic (infinitesimal) sound speed. Shock waves happen from explosions or objects travelling faster than the speed of sound (military aircraft). It doesn't happen in the chamber or squish unless you have detonation.

OH that's rich ! I'M THE SUPERIOR ONE ! Let's see .

what I learned in graduate school studying acoustics....

Superior? I don't know what that means. I'm probably more knowledgeable than most here in that field.

Try the library search here: http://web.mit.edu

Now lets cut thru the chatter I've given you a very good example of a very efficient working chamber , you point me at an empirical example which will undo the one I've mentioned, with your mans technology.

It's not my man's technology.

One person dismissed the concept with no physical or technical reason other than his own opinion. He still might be right in the dismissal, but I offered a reason why it MIGHT be a good idea as a counter-example, and then explained why. Using a level of science/engineering (sans math) that's probably appropriate for the mixed group here.

There are many examples of efficient combustion chambers, especially when you look at the development of them in the last 30 years. So it's not a stretch to think that someone might come up with another idea, to improve on what we have now.

As for your example: methanol has 26% greater flame speed than gasoline does, with a nitro mix it's even higher.... so in both cases less igntion advance is needed; boosted applications also have faster burn speeds so less ignition advance is needed there as well. So there are several factors involved in your example, and they all reduce the need for ignition advance BASED ON FUEL CHOICE AND BASED ON BOOST, not necessarily because of the chamber efficiency.... so they serve only as an attempt to confuse this discussion, IMO.

The only chamber efficiency that would be worthwhile to discuss is a stock chamber vs a modified chamber (using the alteration that prompted this thread in the first place).

I'm not comparing engine A to engine B, but you seem to be.

[airflowdevelop]

are you guys making this stuff up as you go along or what?

Many of us spend a great deal of time and money on this subject. Certain "trend" ideas continue to return time and time again, only to waste even more time and money.

This is a fairly well thought out look at what could be going on during compression..although it has a little bit of billy-bob physics thrown in. remember this thing must run...and at speed...even at a conservative 6000 revs...thats 50 cycles per second...

or am I missing something here...

[liquigas]

or am I missing something here...

A few things are being missed according to my unprofessional estimation.

On the http://www.somender-singh.com website you can find descriptive stories and illustrations that claim to have tested engines with no other modification other than the groove. Positive results.

There are descriptions of a groove and then a slight shave of the head to maintain cylinder size. Positive results.

The groove is claimed to have been used on daily drivers, quarter mile racers, a snowmobile, a lawnmover, an old truck and a beetle, diesel bus and a motorcycle. I have heard of this independently as being used in high spec quad engines, and I'd be very surprised if any pro racers would be willing to divulge their secret (is there any restriction on carving the head of an F1 or NASCAR racer?) to the competition before it became common knowledge.

All results so far are surprising and positive! So the dismissers can squawk all they want and expound proofs of their in-cylinder acoustic theorems, but the proof (and the main reason I like cars) is where 'rubber meets the road'. If you think it isn't possible, get over it.

Curve guy? Go have a look at the US Patent. Mr. Singh covers tunnels through the edge, curved channels and placement of any carve in the head.

The "jet" being aimed at the plug seems less significant than what is, according to Mr. Singh, the primary benefit coming from increased turbulence as the "jet" is directing part of the fireball towards one spot more quickly than the rest of the expanding explosion. Once hitting the edge of the cylinder, why couldn't that momentum, and the as yet unquantified effect of having multiple flame fronts entering the cylinder body, produce a more complete and quicker burn?

Retarding the advance to 50 deg. isn't as cool as the quoted 19 deg. setting, but it does direct more "downward" force on the cam since, at the top, some energy is expended moving the piston connection laterally before the rotation carries in direct line with the piston movement.

The groove's faster and more complete burn reduces operating temperature though, and other fuels would require a closer advance and allow very high rpm. HOWEVER, another of the really consistent findings of the grooving process is a low end torque and power that seems unbelievable, possibly obviating any requirement for higher rpm's.

How common is a dyno in India? The article in POPSCI indicates that it is tough as hell to find. Would you trust the results anyhow? Isn't there someone here willing to do a dyno pull with a small block Chevy grooved and not?!? It may be that Mr. Singh, in India, needs more friends here to determine how beneficial this discovery really is?

Would YOU want to be the Ford engineer who has to report to his section chief that the 5 Billion he spent last year wasn't worth a tiny groove?

[putztastics]

ah, I see, the grooves direct burn flow - not quench flow, the grooves direct burn flow (flame front) to the dead areas of the combustion chamber. That's why Mr. Singh says tight quench clearance doesn't help, it just fights the groove directed burn flow.

hmmmm....very interesting

[katman]

I still haven't seen anything saying how deep to make the cut. From some of the pics, it looks like it gets deeper towards the middle of the chamber. Some pics show 4 cuts, 2 long curved teardrop shaped, and 2 diamond shaped cuts.
He also says dished pistons aren't the best, but what about D shaped dishes? They have the full quench area.
Does the grove have to be in the head? Why not the piston?

[liquigas]

The cut apparently is as deep as necessary to provide a straight shot for the gasses to follow.

Deeper than that would be counterproductive it seems because the whole object is to have the shortest route from spark to wall.

As for combining the types of groove, from what I have seen, the Patent image is just illustrating some examples of the different groove types described in the Patent.

These drawings are not technical illustrations.

[Grocerius Maximus]

Something like 30 years ago an aftermarket manufacturer of 2 stroke motorcycle parts marketed a head that had spiral grooves in the squish band directed into the chamber.

I can't remember that product being on the market for very long.

[automotive breath]

I have recently modified six engines to Somender's specifications. Results have been interesting to say the least. Testing continues on various different combinations. Don't draw conclusions until you try it or talk to someone that has.

1. Clean oil like I have never seen before
2. Idle quality much improved
3. Less likely to have detonation, run more compression or boost
4. More torque and power
5. Total clean burn
6. Reduced fuel consumption

don’t believe me, try it for yourself

putztastics, it works in two directions

[putztastics]

I have recently modified six engines to Somender's specifications. Results have been interesting to say the least. Testing continues on various different combinations. Don't draw conclusions until you try it or talk to someone that has.

1. Clean oil like I have never seen before
2. Idle quality much improved
3. Less likely to have detonation, run more compression or boost
4. More torque and power
5. Total clean burn
6. Reduced fuel consumption

don’t believe me, try it for yourself

putztastics, it works in two directions

Well I have a SB 360 Dodge test mule and a dyno. The engine has .042 quench and closed chamber heads. I see .070 quench is recommended would the quench have to be changed? I could run a before and after test and post the results here. How do I do the mods?