Quench "flame channels" in piston vs. head quench

Unkl Ian · Post by **Unkl Ian** » Wed Dec 13, 2006 10:59 pm

If grooves in the pistons gives the same effect as grooves in the head,
then who wants to test matching grooves in the pistons and head ?

Ideally,there would be a baseline test,with no grooves.
Then repeat tests with one set of grooves,and no other changes.
Then add the second set and repeat.

panic · Post by **panic** » Thu Dec 14, 2006 10:04 am

It appears that the number of cases where improvements have taken place is high enough for the modification to be considered seriously.
However: IMHO this does not mean that the underlying theory as to what is taking place is validated.
We more or less agree that near TDC on the power stroke the groove(s) expels a jet from the squish band into the chamber where is does, or does not do, various things including enhance turbulence, homogenize mixture, blah.
What do these grooves do on overlap, when the same tight clearance occurs? Do the escaping jets affect scavenge? Do non-radial grooves impart swirl that affects port flow (interfering with some, assisting others)? Can a jet cause port flow reversal if aimed at a partially open valve with "lazy" low-lift velocity? Does normal (viz. non-grooved) squish affect overlap patterns now?
This will be very difficult to test on a bench because there's got to be a minimum piston approach speed to get the gas jet working, so flowing a static engine won't show anything - it needs to be cycled.
I don't "know" that this happens, it's just deduction, but I think it would be foolish to try to evaluate cause vs. benefit for groove theory without considering the mixed (and potentially opposing) effects. E.g., where the groove direction favors the exhaust seat area, improved scavenging = higher VE = cleaner charge (less exhaust product) = higher cylinder pressure may have an effect similar to reports of improved low speed response, etc. - the improvement may not be (all) due to turbulence or flame pattern.

moper · Post by **moper** » Thu Dec 14, 2006 12:42 pm

I havent checked back on this in a while..and the stupid "mule" is no further along thatnks to other work. But interesting how polarizing the issue is. Thanks Panic. Am I correctly summarizing you when I say "it's hard to prove as the direct positive influence because there are too many variables in the dynamic you cant isolate and not effect". I have to admit, my reasoning was much more "crude" than many here normally deal with...lol. Which surprises me at the different in schools of thought.

putztastics · Post by **putztastics** » Thu Dec 14, 2006 12:55 pm

What stupid "mule" are you talking about?

Twinscrew · Post by **Twinscrew** » Thu Dec 14, 2006 1:16 pm

If someone in the Central Florida area is willing to provide a dyno for testing, I have 3 engines I'm willing to perform the modifications on.
A 4.9L inline six, a 5.8L v8, and a 2.0L inline four. All are factory stock in good running condition with no issues, currently. I believe this would make up a good mix of engine configurations and show generalizations with regard to performance improvements if any are to be found. I would be gald to document these projects from start to finish and post all findings here, in an unbiased manner, good or bad.

MadBill · Post by **MadBill** » Thu Dec 14, 2006 5:03 pm

panic wrote:....What do these grooves do on overlap, when the same tight clearance occurs? Do the escaping jets affect scavenge? Do non-radial grooves impart swirl that affects port flow (interfering with some, assisting others)? Can a jet cause port flow reversal if aimed at a partially open valve with "lazy" low-lift velocity? Does normal (viz. non-grooved) squish affect overlap patterns now?...

Good thinking to expand the frame of reference to the 'other' TDC case, Panic! I think a major factor though would be the relative mass involved. At TDC on the firing stroke, pressure could be as much as 1,000 psia, whereas on the overlap, if the exhaust is scavenging at max efficiency, it might be as low as 6-7 psia. (12-14"H2O vacuum) The gas density and thus ejected mass and resulting kinetic energy/momentum could be over 100X greater in the former case, presumably producing a much greater effect.

No Problem · Post by **No Problem** » Thu Dec 14, 2006 6:52 pm

AS THE OWNER OF NO PROBLEM RACEWAY, I HAVE PERSONALLY WITNESSED THE LOWER ELAPSED TIMES OF CARS WITH THE COMBUSTION CHAMBERS THAT WERE MODIFIED BY "ENGINE BREATH". I WATCHED A 2,800 POUND CORVETTE GO FROM 10.20'S TO 9.90'S. I HAD TO REQUIRE THE OWNER TO GET HIS NHRA PHYSICAL, HAVE HIS CHASSIS CERTIFIED, AND GET THE PROPER FIRE SUIT AND WINDOW NET INSTALLED BECAUSE NOW HE WAS RUNNING FASTER THAN 10.00-FLAT.

I WAS SO IMPRESSED BY "ENGINE BREATH'S" WORK THAT I GAVE HIM A SET OF MY HEADS FOR MY SUPER-STOCK CAMARO TO HAVE THEM MODIFIED.

WHILE I DO NOT PROFESS TO BE AN EXPERT ENGINE BUILDER, I CAN SPEAK AS AN EXPERT DRAG RACER. TO FIND 2-TENTHS OF E-T BY MAKING A MODIFICATION TO THE COMBUSTION CHAMBER JUST AMAZED ME.

Ed-vancedEngines · Post by **Ed-vancedEngines** » Thu Dec 14, 2006 7:15 pm

Ok,
So who is Engine Breath?

Is he one of your local engine builders? Or maybe that is a nickname that he is using but does business with a different name?

I have never seen you on Eddie's Board. Are you a member there using a different name than this one you have here?

About the groves in the head discussions, we have all had quite a number of discussions about this subject in several different threads. I am not shooting it down or praising it. Currently I am really in the dark. I can see that maybe properly directed channels could be helpful in some areas of engine of certain designs in some instances. BUT in a race enginbe I have not seen in my head or wisdon, how there could be any advantages unless it is to be like a band-aid for an existing problem.

The one here in this forum that seems the most sold on the concept is also at the same time advocating an increase of the quench clearances with the using of these grooves. I have seen several pics he has posted of the different groves he has cut and I do not see any semblance to the reasons of the changing patterns of the grooves in the different but similar style of head applications.

It is possible that he is really on to something and is maybe trying several different variants of the concept.

Ed

panic · Post by **panic** » Thu Dec 14, 2006 7:15 pm

The gas density and thus ejected mass and resulting kinetic energy/momentum could be over 100X greater in the former case, presumably producing a much greater effect.

I'm not sure I agree. Combustion pressure is vastly greater, so a gas jet escaping a groove would not "penetrate" as easily after ignition - the results may be limited to the milliseconds before the flame kernel propagates and gas pressure spikes. The jet itself is only under compression pressure (at least when it enters the chamber) since it's not ignited and has no extra energy content. For example, the squish band height will be near nominal between 20 BTDC and TDC, and although spark has occured, the gas pressure is still confined to a relatively small area radial to the electrode until after TDC.
On overlap, the relatively low pressures (and low density) would offer only minimal resistance to deflection/redirection by a gas jet.

automotive breath · Post by **automotive breath** » Thu Dec 14, 2006 7:19 pm

No Problem wrote:AS THE OWNER OF NO PROBLEM RACEWAY, I HAVE PERSONALLY WITNESSED THE LOWER ELAPSED TIMES OF CARS WITH THE COMBUSTION CHAMBERS THAT WERE MODIFIED BY "ENGINE BREATH"...

Thanks No Problem, I appreciate the recognition here and at the awards banquet.

I learned a lot with the Vette and put it to work on Josh’s Camaro, sixty-foot times in the 1.2s last Saturday made my day. This with the ignition timing retarded 6 degrees. (Yes we do race in December thanks to the jet dryer).

P.S. it’s “Automotive Breath”

putztastics · Post by **putztastics** » Thu Dec 14, 2006 7:28 pm

moper · Post by **moper** » Thu Dec 14, 2006 8:57 pm

Sorry Putz, I was referring to the 451 (440+.060) engine "experiment" i have on the stand still unassembled. That was the start of this thread. It was in pcs when I first posted the question, and has only collected some dust on the cover...lol.

automotive breath · Post by **automotive breath** » Thu Dec 14, 2006 10:40 pm

panic wrote:...This will be very difficult to test on a bench because there's got to be a minimum piston approach speed to get the gas jet working, so flowing a static engine won't show anything - it needs to be cycled....

Monitoring fluid flow during engine cycling is an interesting topic. Smokey spoke of his inability to "see inside the chamber" resulting in theories of what was actually happening.

Not only must the engine be cycled but it must be running under intended operating condition to develop true dynamics. The desired effects can be accomplished with x-ray, ideal for getting a snap shot of squish flow, exhaust scavenging and such.

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Unkl Ian · Post by **Unkl Ian** » Thu Dec 14, 2006 11:15 pm

Maybe something like this,with high speed photography,or a strobe ?

http://www.eng.warwick.ac.uk/oel/course ... /ic008.htm

Boport · Post by **Boport** » Thu Dec 14, 2006 11:37 pm

mpgmike wrote:- 2000 Ford Ranger 2.5; from 21 mpg to 27 mpg and had the power of the 3.0 V-6

Mike
www.PowreHaus.com

All this from grooves only or is this from the portwork done as well? I see a significant amount of porting done in the pictures of the ranger head and that would invalidate your performance claims if included as part of your back to back testing.

I own a vehicle with that same engine and am to the point where I want to test this myself on a dyno to put this to rest or be another believer. Please elaborate on your testing!

Bo