Chamber Grooves - what do you guys think?

[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?

[putztastics]

Why wouldn't one be better off doing what Smokey did, running the intake manifold at 440 degrees to totally vaporize the fuel before it gets to the chamber?

I wanted to try that, that's why I set up my dyno, but i have never pursued it.

Being flush with money will do that to you I guess.

Sad.

[automotive breath]

I have always wanted to duplicate what Smokey did but it's very complex. The two ideas focus on the same problem in very different ways. The problem being that combustion in the internal combustion engine is very inefficient. Improve on the combustion efficiency and power levels will increase and fuel consumption will decrease. Simply raising the compression ratio of an engine increases the combustion efficiency with in the limits of the available fuel. Having the ability to raise the compression ratio with out detonation is the key. For the first time I have found a simple modification that allows increased compression with out the need for high octane fuel!

http://members.cox.net/raunch/LT1%20Shon%201

http://members.cox.net/raunch/Shon%204_edited.jpg

[putztastics]

I don't think what Smokey did was that complex.

The basic idea behind the high mileage carburetor is totally vaporizing the fuel before it gets to the combustion chamber.

What Smokey did was improve fuel vaporization efficency before the air/fuel mixture got to the combustion chamber by heating the air fuel mixture to 440 degrees which is higher than the end point of vaporization for pump gasoline. The turbocharger on that engine was simply a "check valve" used to gain back mixture density lost by heating it to 440 degrees.

How efficient are carburetors at vaporizing fuel? 30%? How efficient is fuel injection at vaporizing fuel? 30-40%?

How much of the fuel is vaporized in the chamber before combustion? More than right after the carbutetor or fuel injection but it's still not 100%.

What will happen if 100% of the fuel is vaporized before it gets to the combustion chamber?

I think the gas mileage might go up.

It seems that it might be the long molecules of fuel that vaporize last that are the the cause of detonation. Those molecules were vaporized in Smokey's engine by the 440 degree intake mixture temperatures before they got to the combustion chamber. I remember a letter to the editor of Popular Science after the article on his V-2 engine was published. The writer of that letter commented on how interesting it was that Smokey used total fuel vaporization before combustion as a way of lowering the octane requirement of the engine.

[putztastics]

The two ideas focus on the same problem in very different ways.

I'm not sure it is the same problem. I see two separate problem areas;

1) Fuel vaporization efficency.

2) Combustion efficency.

As we all know liquid fuel does not burn. Trying to vaporize liquid fuel in the chamber right before combuation is too late.

Your modification might increase combustion efficiency but not vaporization efficency.

Imagine the potential results if one improved both.