Singh Groove testing redux and CFD for groove positioning.

[automotive breath]

Ahhh ! Now I remember, thank you!

I think the 2 groove I mentioned was with regard to a "Hemi". I should probably go back and look at it again.

I almost forgot the first two groove I did.

[Windsor377]

Thank you AB.

[putztastics]

Reference;

Detonation starts on intake side of chamber. True?

Also these are the best engine knock recordings I have heard, especially the ones on the right where the timing is varied;

Knockbox sound recordings

[Greezer]

put that bucket on your head and contain your thoughts

[Troy Patterson]

If detonation begins in the cold region of the combustion chamber, such as at the edge of the intake valve, perhaps the thing to do is aim a groove at that area. I would probably do this in addition to a groove aimed at the plug.

Troy Patterson TMPCarbs.net TMP Carbs

[dizuster]

Although you may not see any huge gains in this type of testing. My gut feeling is that the grooves wouldn't ever make any power by themselves. But what they will do is open up the door for a limited octane motor (pump gas) to run more timing/compression. That will make more power.

A better test is to build a 12:1 iron headed motor. Put it on the dyno with pump gas and see how much power you can make (which means non-optimum timing) Then put the grooves in the head, and see how much more timing you can crank into it on the same fuel.

Now that would be a good test. . .

[larrycavan]

FWIW..

I'm not certain if the grooves are funneling the flame to the charge that's laying in the quench area or laying a path for that charge to squeeze out to where there's a flame...or a combination of both..

If I were going to do the grooves I'd lay back the edges of the groove to allow either situation an easier opportuinity to present itself to the other...charge to flame..or flame to charge..

JMO

[Rick360]

FWIW..

I'm not certain if the grooves are funneling the flame to the charge that's laying in the quench area or laying a path for that charge to squeeze out to where there's a flame...or a combination of both..

I've read several of these threads about these and have always wondered if the grooves were providing the path into the quench area for the flame, instead of the other way around, just like you say Larry. I think this is how they work, if they do.

I never could see how the area with the most distance (the groove) was supposed to "shoot" the fuel/air out. The widest gap approaching tdc would create less pressure than the rest of the quench area.

Rick

[stevek]

As the piston comes up to the squish pad an amount of air/fuel is evacuated from the squish space and into the chamber. This movement has an amount of kinetic energy that can push more than just what left the squish space - that is - as it comes out of the squish space it creates additional turbulence in the chamber. This has the benefit of exposing a larger amount of air/fuel to the oncoming flame front. Essentially the flame geometry is increased and you get a better bang. Put a groove in and you begin to direct that squished up mixture into a small but high kinetic energy stream. Now you have to work out where best to direct it, so that you can work with the existing chamber turbulence (and not against it!) to expose the most air/fuel to the spark and flame front.

Think of the groove as an inverted flow vane.

For a more thorough understanding of the grooves, I suggest that you thoroughly read Chapter 4 of Gordon P. Blair's "Design and simulation of four-stroke engines". Be sure to pay particular attention to the pages on 'squish', around page 414 from memory. The answer is all there, in black and white print. No secrets. No magic.

[automotive breath]

I just want to maximize what I have. Any feedback will be greatly appreciated.

Lately I have been doing variations of this. The people that I have done
this for like the results. Grooves were cut with 1/6" ball end mill 1/16"
deep, finished by hand with a file; deeper and 1/8" wide at the chamber.

[putztastics]

To whoever may not have seen the first grooves dyno test;

Dodge 360 Grooves Testing, 2-17-06.

Also refer to the links in the first post on this thread for more backbround information.

There is really no doubt they improved power in the 2200-3500 WOT range and lost a little bit of power in the 4000-6200 WOT range.

I have to wonder if the slight loss of power in the upper RPM range is groove flow interference with the flame front in the spark plug area. Don't really know what else could explain it.

Note the gains I mention are averages across an RPM band, not peaks, the dyno graphing software allows one to average any channel across any RPM band.

[SchmidtMotorWorks]

There is really no doubt they improved power in the 2200-3500 WOT range and lost a little bit of power in the 4000-6200 WOT range.

Thanks for posting the results, is this what you expected?

[automotive breath]

I have modified two engines with multiple grooves angling towards the
exhaust valve. I wanted to point them towards the intake side, the valve
was too close to the deck to do so. This weekend we were able to get
several 1/4 mile runs with one. Initial indications are great. Pump gas
383 in a 3400 LB 71 Nova. 10.70 @ 124 with 1.44 60 ft times, still working
on the tune up.

[CRE2004]

Forgive me if this has been brought up or answered before, but has a before and after test been performed on this modification? Make 1/4 mile passes, pull heads, modify, make follow up passes?

[automotive breath]

.... has a before and after test been performed on this modification?
Make 1/4 mile passes, pull heads, modify, make follow up passes?

Same day, no.

Take a well known car, run, pull heads, modify, make follow up passes
on another day. Yes, I have done this many times. Biggest improvements
were found when the initial engine had auto-ignition problems.