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Before/After grooved head pictures

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Before/After grooved head pictures

Postby automotive breath » Sat Sep 02, 2006 3:42 am

These pictures are from a 13.5:1 compression 383 that I modified last year. The heads are pro topline 220s, the modifications that were done are the grooves and a clean up porting. The piston to head clearance was 0.038" at assembly, both pictures are after 100s of runs.

Comments?


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Postby Ed-vancedEngines » Sat Sep 02, 2006 4:43 am

Hmm'
Looks like the grooved one is getting hotter but it also by looks is appearing to be producing more power. The ungrooved pic to me is looking like an almost waste as far as the little bit of a burn pattern it is showing.

I would think that the one that is grooved should be needing either more fuel, less timing, colder plugs, or lower engine heat.

You did say that both of those were set up with the same clearances and had about the same usage?
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Postby highVE » Sat Sep 02, 2006 6:10 am

Auto Breath,

How was the flame travel apperance on the top of the piston now as apposed to prior the groove? any differant? I'm sure a plug reading after a hard run would show a differant story with the groove than without as well. It does look like it made a differance! How was the performance? what was the ET/MPH gain?

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Postby automotive breath » Sat Sep 02, 2006 11:13 am

Ed, both examples are from the same engine with the same usage, 3800 lb bracket race full size Chevy pick-up truck 10:60 ET, the only difference is the modifications I mentioned and possibly the tune-up, nothing major there.

Mike, I didn’t see the pistons last year, this picture was with the grooved head. He runs a large dominator carb., I have never been able to read plugs with those. I have been able to lower ET over 0.03 seconds and almost 4 mph faster. The porting and grooves were done at the same time so I can’t say where the performance came from.


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Last edited by automotive breath on Sat Sep 02, 2006 11:15 am, edited 1 time in total.
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Postby highVE » Sat Sep 02, 2006 11:15 am

well from the looks of that piston picture, you have very good flame travel evan having the dome !!

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Postby John N » Sat Sep 02, 2006 12:36 pm

VERY intersting!

What exactly is the function of the groove? Just to spread the flame? Had you seen it done before or did you just do it out of the blue? I'd like to see some more about wheather or not this makes more power. Would those pointy edges get hot and cause detonation prematurely in a street driven car? I may try it.
Last edited by John N on Mon Oct 02, 2006 9:52 pm, edited 1 time in total.
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Postby machine shop tom » Sat Sep 02, 2006 1:05 pm

automotive breath wrote:Ed, both examples are from the same engine with the same usage, 3800 lb bracket race full size Chevy pick-up truck 10:60 ET, the only difference is the modifications I mentioned and possibly the tune-up, nothing major there.

Mike, I didn’t see the pistons last year, this picture was with the grooved head. He runs a large dominator carb., I have never been able to read plugs with those. I have been able to lower ET over 0.03 seconds and almost 4 mph faster. The porting and grooves were done at the same time so I can’t say where the performance came from.




"The porting and grooves were done at the same time so I can’t say where the performance came from."

Too bad the changes weren't made one at at time (I realize that can be expensive). There is no real way of telling which made the bigger difference.

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Postby jb race » Sat Sep 02, 2006 3:23 pm

hi just wondering what the theory behind the groove was?
just wondering i might give it a go too.
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Postby Keith Morganstein » Sat Sep 02, 2006 3:32 pm

jb race wrote:hi just wondering what the theory behind the groove was?
just wondering i might give it a go too.


http://www.popsci.com/popsci/futurecar/ ... drcrd.html
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Postby #84Dave » Sat Sep 02, 2006 8:37 pm

A number of years ago, I had a constant condition whereby the tops of the pistons in my 13.5:1 unlimited 4-cylinders always had about 40%-50% of the top of the piston that was 'clean' under the head quench area. a goos portion of the head quench area was also 'clean'. A light tan on the piston top/chamber everywhere else. Then I read an SAE paper by a couple of Japanese engineers regarding 'slant quench' and their CFD explanation as to why it worked. So, along with 'dimples' on the piston tops to form 'Von Karmon' rings, I began to slope/slant the quench in my cast-iron chambers. With the head gasket, I had .042" piston top-head clearance at the bore line. I sloped the quench areas in the chambers upward to where I had .060-.070 clearance from the piston top to the edge of the quench pad on the head. From a color perspective, I was stunned at the results on the first engine I used the scheme. The light tan color then extended clear out to the edge of the piston top and the chamber was colored throughout. The engine ran a verifiable .13 seconds quicker, average through 4 practice sessions, on our 'home' 1/4-mile paved oval. I pulled 2° total ignition timing out, from 34° to 32°, and the car was then quicker a solid .2 seconds per lap. From an engineering standpoint, I have no data as to why it worked. Only the lap time transponder said it worked. I suspect the 'ditch' in the piston top accomodates some quench 'pump' and/or turbulance, that improves or allows quicker/better completion of the mass-fraction burn in the chamber. If I remember correctly, the 2-dimension CFD in the SAE paper showed some turbulance with their slant quench. But many of us would like to know the engineering answer as to why these little 'tricks' in the chamber appear to improve combustion. Also, it may have been answered here previously but what causes a 'clean' piston top? So rich it won't burn, or so lean there is nothing to burn?

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Postby Windsor377 » Sat Sep 02, 2006 8:45 pm

Now that we're going there, did you flow the heads before and after the slant squish/tapered deck?
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Postby #84Dave » Sat Sep 02, 2006 11:08 pm

Yes....... the intake ports in the head flowed 197cfm, +/- 4cfm, with 25" across the bench before and after the modification. Corrected head flow changed little, that we could detect. The head was a 2.0L SOHC Ford with 1.800" intakes and 1.450" exhausts. Dave
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Postby larrycavan » Sun Sep 03, 2006 4:47 am

Max Effort wrote:
jb race wrote:hi just wondering what the theory behind the groove was?
just wondering i might give it a go too.


http://www.popsci.com/popsci/futurecar/ ... drcrd.html


So where did it go from there? I see a 9.3.2006 date on the main page but that's no real indication of the source date of the article. Would be interesting to know if the tests have been done and what the results were.
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Postby larrycavan » Sun Sep 03, 2006 4:58 am

Ed-vancedEngines wrote:Hmm'
Looks like the grooved one is getting hotter but it also by looks is appearing to be producing more power. The ungrooved pic to me is looking like an almost waste as far as the little bit of a burn pattern it is showing.

I would think that the one that is grooved should be needing either more fuel, less timing, colder plugs, or lower engine heat.

You did say that both of those were set up with the same clearances and had about the same usage?
Ed


It looks to me like two different fuels were used. Then again, the coloring may be different on the valves because without the groove, more of the mixture was being burned directly in that portion of the chamber.

Interesting how there appears to be more complete burning on the narrow squish area on the side opposite to the groove location, where the spark plug hole is.

Have you tried these grooves on any other chambers?
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Postby Keith Morganstein » Sun Sep 03, 2006 10:12 am

larrycavan wrote:
Max Effort wrote:
jb race wrote:hi just wondering what the theory behind the groove was?
just wondering i might give it a go too.


http://www.popsci.com/popsci/futurecar/ ... drcrd.html


So where did it go from there? I see a 9.3.2006 date on the main page but that's no real indication of the source date of the article. Would be interesting to know if the tests have been done and what the results were.


this has been kicked around for a while. Has a 2001 US patent. I have read the patent before. You can also type "Somender Singh" into google and come up with some reading.


I haven't experimented with it. Here are more links.

http://www.somender-singh.com/

http://speedtalk.com/forum/viewtopic.ph ... highlight=

http://speedtalk.com/forum/viewtopic.ph ... highlight=
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