Chamber Grooves - what do you guys think?

General engine tech -- Drag Racing to Circle Track

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putztastics
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Post by putztastics »

Well to make that clearer I read in Popular Science that GM had bought Smokey's patent on that engine.

It looks like some of Smokey's hot vapor engine patents have expired.
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Post by lil289 »

Has anyone heard of GEET?
http://www.teslatech.info/ttstore/books/750001.htm

I think the guy who was developing this turned out to be a fraud though.
I heard this guy on a radio show and what sounded interesting to me was that his system involved running the fuel line through the exhaust to heat it. On the show I remember them mentioning that someone long ago had developed a carburetor that was cabaple of 100 mpg but then the oil companies started putting additives in the gasoline and it made this carb ineffective. Has anyone heard of this?
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Post by jacksoni »

Can you say "Vapor Lock"?
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Acetone

Post by automotive breath »

lil289 wrote:Has anyone heard of GEET?
No. But I tried this... and it worked!

http://www.pureenergysystems.com/news/2 ... 9_Acetone/
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Post by lil289 »

Are you serious??? Tell us more.
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Post by automotive breath »

lil289 wrote:Are you serious??? Tell us more.
The site says it all. 2.5 to 3 oz per 10 gallons of gas. My 4 banger went from 31 to 36 MPG on the interstate!
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Post by putztastics »

lil289 wrote:I heard this guy on a radio show and what sounded interesting to me was that his system involved running the fuel line through the exhaust to heat it. On the show I remember them mentioning that someone long ago had developed a carburetor that was cabaple of 100 mpg but then the oil companies started putting additives in the gasoline and it made this carb ineffective. Has anyone heard of this?
That's the Pogue carburetor.

The whole theory behind most of the high mileage modifications including Smokey's vapor engines is totally vaporizing the fuel before combustion using exhaust heat. Smokey did it in the intake manifold, Charles Pogue did it in a carbutetor.

If you improve the amount of fuel vaporized from 30%-40% to 100% the fuel mileage should go up, right?

***************************************
automotive breath, you going to e-mail me about the grooves test or what?
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Post by lil289 »

With grooved heads additional turbulence helps to keep the fuel air mixed. In addition a path for the flame is created into the squish area resulting in clean burn, opening the squish distance inhances this burn.
Automotive Breath,
Very interesting tests. What suprises me is that the general consesus seems to be that the tighter the quench clearance the better. Some people run as tight as .025" with steel rods and limited RPM. Tighter quench is supposed to allow for higher compression because it re-accelerates the air/fuel mixture and I think it creates a faster burn too allowing for less advance. In your testing, did the motor like any changes in timing? More advance? Less? Also, I'm not sure if you tested this but how was the fuel economy? Did it get better or worse? Another interesting test might be to see what changes there are in EGT's. If it gets lower it may be an indication that you're getting a more complete burn in the cylinder rather than sending still burning gasses out the exhaust.
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Quench Clearance

Post by automotive breath »

lil289 wrote:Automotive Breath, Very interesting tests. What surprises me is that the general consensus seems to be that the tighter the quench clearance the better. Some people run as tight as .025" with steel rods and limited RPM. Tighter quench is supposed to allow for higher compression because it re-accelerates the air/fuel mixture and I think it creates a faster burn too allowing for less advance.
Smokey Yunick's Chevy Engine Guide 1987 wrote:Quench Clearance and Deck-Height

Although a quench-type chamber is not very desirable from a performance standpoint, nearly all production cylinder heads have quench areas. Actually, the term “quench” is a misleading description. The quench portion of the chamber is that area where a flat portion of the head and a matching flat portion of the piston close together at top-dead center, significantly reducing the volume of the chamber.

From the name, it sounds as if the quench area is supposed to restrict combustion, but in fact, the quench design is used to enhance combustion in a chamber that has a relatively large diameter. When the piston and head quench surfaces come together during the compression-ignition changeover, the combustion gases in this area are pushed over into the open part of the chamber, creating turbulence that improves the combustion process.

For maximum performance with a quench-type cylinder head, the quench clearance should be as tight as possible, but there must be sufficient clearance between the two surfaces to prevent any contact at top-dead center.

The desired quench clearance is actually a figure selected as random by the engine builder, and once it is selected, the builder must calculate a corresponding piston deck-height (the distance from the deck of the piston to the deck of the block). The total quench clearance will include the piston deck-height and the compressed thickness of the head gasket (the thickness after the cylinder head is clamped down with the recommended fastener torque). Therefore, the thickness of the compressed gasket – which is normally supplied by the gasket manufacturer – is subtracted from the quench clearance, and the resulting dimension is the required deck-height.

It is hard to recommend a desired quench clearance that will be correct for all engines, but I think 0.038-inch of clearance between the quench surfaces is an absolute minimum in an engine with a 4.00-inch bore and about 0.007-inch of piston-to-wall clearance. However, if the piston clearance is greater, say 0.009- to 0.010-inch, this may not be enough. A safe figure for all-around performance is 0.040-inch. Anything up to about 0.045-inch is probably okay, and I wouldn’t worry about a little extra clearance as long as it was close to these recommendations.

But remember, if you let the quench clearance open too much – to 0.060-inch or more – you’re going to lose power. This much opening at the quench will allow excessive amounts of the intake charge to remain in the quench area as the piston reaches top-dead center, and especially if the piston has a high dome to obstruct the spread of the flame front, these gases may not be properly combusted during the ignition phase. This significantly reduces combustion efficiency.

I’ve also heard there are some builders who claim an engine will make more power if you let the piston “smack the heads a little.” I think this sort of talk is mechanical nonsense, and I would not recommend it under any circumstances. When you disassemble an engine for inspection, always check the piston and head decks on the right bank for signs of contact. Because of the crank rotation and piston sway in a conventional V8, the pistons in the right bank tend to show signs of contact before those on the left, and if you see signs of contact, I think you should open the quench clearance a little bit or you’re going to bread some parts.

Another important thing to watch in the quench area is to make certain that when the piston is at top-dead center the quench area is exposed to the open part of the chamber. If the quench decks are not parallel or angled slightly toward the valves, the quench area may be closed off from the rest of the chamber as the piston dwells near the top of the stroke, and gases trapped in the quench will not be combusted properly, this can lead to secondary combustion and detonation problems.
I have always followed Smokey's lead. I have tried everything I can think of including having the piston hit the head at RPM, like Smokey said "I think this sort of talk is mechanical nonsense".

In attempt to run high compression on low octane fuel I have recently started to open the quench clearance to .070" with interesting results.
In your testing, did the motor like any changes in timing? More advance? Less?

After the modification running a .070" quench clearance the engine ran clean with 40 degrees total advance with no signs of detonation. I am slowly coming down on the total advance and I have not lost bottom end and I have been rewarded with a stronger midrange and top end charge. Presently I'm running 36 degrees total, I plan on going to 34 degrees total to see if it responds.
Also, I'm not sure if you tested this but how was the fuel economy? Did it get better or worse?

The fuel consumption measured at the drag strip has been reduced near 35%
Another interesting test might be to see what changes there are in EGT's.

I don't have a way to measure my EGT, my guess is its much lower.
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Post by lil289 »

35% reduction in fuel consumption? That's awesome! I've often wondered if there was another way to measure EGT's short of drilling holes into your primary tubes and welding bungs, installing sensors, wiring, etc. McMaster has some non-reversible temperature liquid that you could brush onto the headers ranging from 175 degress F all the way up to 2000 degrees F. If you have coated headers it obviously won't be accurate thought. Part # is 3261K93 It may not be as accurate as probes inside the tubes but at least it can give you an indication of the amount of change and in which direction. By the way, are you familiar with Larry Widmer's "Soft Head" concept? You can read some of the magazine articles that have been published about this. Interesting stuff. Keep us posted with your findings.
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Post by Ape »

lil289 wrote: By the way, are you familiar with Larry Widmer's "Soft Head" concept? You can read some of the magazine articles that have been published about this. Interesting stuff. Keep us posted with your findings.
Larry widmers soft head concept is founded on michael mays fireball concept and his tests on jaguar and volkswagen engines with ultra high compression.
There is always advancement to be made.
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Post by automotive breath »

A small number of people here have shown interest in the work I have been doing grooving SBC heads. I got a couple of sets in the shop for porting and grooves. This is a set of pro topline 220s from a 383 bracket engine. The best to hope for this one is more testimonials, no dyno test scheduled. The engine has been together for several hundred runs and the only modifications being done are the grooves and mild porting.

The cylinder head squish area displays relatively uneven burn around the squish circumference near the intake valve and the gasket area. I hope to get these heads back next year to see if the burn pattern has changed.

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Post by MadBill »

Just stumbled on this. Looks like the discussion has died out at least for the moment. Maybe everybody is off testing for themselves?
One test that would reveal at least the potential of the groove to impact combustion would be to run back to back dyno tests with A. .070" squish/quench, B. thinner gaskets for .030" squish , C. 0.070" with grooves and D., 0.030" with grooves.
Running a fairly high CR engine equipped with knock detectors on a variety of fuels and looking at power, F.E. and knock resistance should certainly answer a lot of questions. Now, where did I leave that winning lottery ticket I was going to use to pay for the dyno time? :-k

PS: The thread digressed at one point to Smokey's hot vapor engine and to the use of acetone to reduce surface tension and improve vaporization. My question is: If complete vaporization is such a panacea, why do natural gas and propane engines (even those using liquid propane injection) get at best virtually identical fuel economy to gasoline ones? (and before anyone claims they don't, I worked for 10 years on GM's Alternative Fuel programs. The bi-fuel natural gas trucks and car we sold were usually certified within 1% city and highway mileage (energy basis) on the two fuels.
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Post by Calypso »

Let me take a stab at this. For staters, I think it would work.

1. Compression stroke burn improvement: Hi speed jet in the middle of the chamber would cause 2 contra rotating swirls (intake and exhaust side) that improve the burn rate and make it more complete by throwing gas into the flames. Actually this mod would likely allow more compression by swirling the unburned detonation sensitive mixture from the area cylinder wall side of the intake valve. (based on the thinking that better ionized exhaust side mixture tends to burn first and compress the end gas to the intake side)

2. exhaust stroke idle improvement. This is based on how I think reversion behaves. Most of the flow in the ports at low lifts is along short turns. Hi speed jet near intake short turn causes local pressure minimum pulling mixture to the chamber at overlap. Pressure recovery from the jet at plug side causes a local hi pressure region at exhaust port short side inhibiting exhaust flow into the chamber.

#2 also would explain why bigger quench distance would improve burn: Low pressure area at groove would be able to more easily evacuate the the unburned mixture from quench pad area.

To me it makes sense. I think I'm going to try it... with couple of obvious improvements. :D
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Post by jacksoni »

As MadBill says, have to do a real a-b-a testing with only the single design change. Automotive breath says will just put these grooves in and port them up a bit and see what happens. Indeed the chamber burn pattern may look different after but how do you tell what changed what?

The acetone thing is similar. Hey, my mileage increased a bunch. Far as I am concerned, the biggest determining factor in mileage in any given car is how heavy is your foot. To say I get say 25mpg normal and then put bit of acetone in and hey it goes to 28 is just bogus. My foot got a lot lighter doing the test. My new car has mileage function. If I wasn't afraid to put the acetone in it and wreck something, put it on cruise control, both ways over a stretch of road, several times and get some numbers. Then put the acetone in and do the same. Or real on the dyno, don't change anything else. It ought to be easy to prove (or not). I work in a job where the controlled clinical trial is king and anecdotes aren't worth anything. Should be easy to do. Someone step up.
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