I have seen the pictures of the grooves people are cutting into their heads, and they all appear to be straight channel grooves. I was wondering about something similar in shape to the cross section of a velocity stack. Beginning larger and curving smaller. Do any of you agree that this may in fact increase the velocity of the hot jet of burning fuel? I think with the speed and pressure it could make a huge difference over a straight groove. I'd like to see other thoughts about this, lets change the way people think. Imagine if every car came with this. :)
I'm not ready to do it to my car till I have more funds to tear it apart, but as soon as I do, I'll have all the knowledge necessary thanks to this site.
Nathan
Post edited by: kirch1999, at: 2005/07/28 01:57
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Re:Groove shape
Date: 2005/07/29 09:38
By: Winky
Status:
My guess is that the groove does not actually have any gasses in it for that long. The initial jet would be created as the blast expands and finds a channel to move more directly then the blast does. Having the rest of the channel cut into the head makes a groove that is parallel with the cylinder top while all of the gasses and expanding fireball are headed towards the bottom of the cylinder. So, it seems to me that the real action is happening just as some of the gasses squirt away from the main fireball when they find the groove opening.
Some serious effort to shape the part of the groove that first comes into contact with the flame front would be useful.
Where can someone find out more about the grooves that you describe?
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Re:Groove shape
Date: 2005/07/30 20:42
By: Broadbent
Status:
It might actually be that stopping the groove short would be useful to produce a turbulent 'bucking'. While a NACA shape that is twisted slightly would produce a vortex whose centripetal force could add to the expansion of the gasses.
Post edited by: somender, at: 2005/11/30 03:21
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Re:Groove shape
Date: 2005/08/04 06:14
By: kirch1999
Status:
Karma: 1
I'm going to play around in a drafting program and show what I mean.
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Re:Groove shape
Date: 2005/09/19 08:18
By: Lenny
Status:
From reading the Popular Science article and other postings on this website. I don't think the groove has any affect after the combustion process starts. The clearences in the squish area are too tight, and the groove is too narrow to sustain a clean burn (IMHO).
What the groove does seem to do is force a much more wicked swirl in the cylinder before TDC. As the piston is rising to TDC, the mixure is forced from the squish area through the groove. This stream is directed towards the spark plug so that when the spark ignites the mixture, there is a maximum amount of turbulance in the chamber which promotes a full burn of fuel.
I am curious to know if multiple grooves (2 or 3) pointing to the spark plug would have any affect.
spark plug ---> * grooves --> / I
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Re:Groove shape
Date: 2005/11/26 18:28
By: John W. Kelly
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Karma: 0
I don't think that swirl has much to do with air/fuel movement while the piston is travelling towards TDC. Swirl is most likely generated by intake charge inertia and the fact that the cylinder's volume is increasing on it's way to BDC. As for the turbulance you may be seeing, I think you are quite right. I have just recently received a set of heads from a fellow enthusiest that have seen some sort of damage due to a broken electrode or some other problem. As a result, the chamber has some damage on the squish pad. I felt that the resulting gouge from this damage would produce such an difference in how the chamber reacted that reproducing the gouge must be considered.
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Re:Groove shape
Date: 2005/12/02 13:42
By: John W. Kelly
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Karma: 0
I'm curious as to where you index the open section of the plug's electrode. I direct mine towards the exhaust guide or center of the exhaust valve. I think that this would play a part in the combustion process. I'd like other people's thoughts on this!
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Re:Groove shape
Date: 2006/06/14 22:04
By: John W. Kelly
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Karma: 0
As of now I have grooved two sets of heads. The first set has yet to be installed but I have just finished up the second set and they are in the car and running (13 June 06). The driver of this car has been instructed to record fuel consumption since this is our primary concern. On this second set, I only used a single groove on the opposite squish pad from the plug as chamber volume was already a bit large. I'll be posting information as we go. One thing I noticed is that the car seems quieter. This is an air cooled VW sedan.
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Re:Groove shape
Date: 2006/06/17 12:51
By: automotive breath
Status:
Karma: 3
John W. Kelly wrote: As of now I have grooved two sets of heads. ....
Great, did you get any pictures?
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Re:Groove shape
Date: 2006/06/17 21:28
By: mpgmike
Status:
Karma: 4
I angle the outer electrode toward the head, with a slight tilt toward the exhaust valve to straight (anywhere in between is acceptable on a street engine).
My grooves start at about 0.010" deep at the gasket surface and progressively get deeper and wider at a 5 degre angle (on the 2.2 Chrysler heads) up to 0.015" wide. I agree with what I call the "funnel ram" effect where the velocity would increase as the cross-sectional surface area of the groove diminishes.
Mike
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Re:Groove shape
Date: 2006/06/19 14:24
By: jsenner
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Karma: 0
I've grooved a Geo Metro and gotten the same basic results as others have mentioned. The car most definitely runs quieter. Low RPM performance is very very nice. The link to pictures of my grooves is here; http://jeremiahsviolins.com/grooves.htm
We'll see if great fuel economy happens or not...
Jeremiah
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Re:Groove shape
Date: 2006/06/20 00:03
By: John W. Kelly
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Karma: 0
As of now, I don't have a digital camera.
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Re:Groove shape
Date: 2006/06/27 00:24
By: jsenner
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Karma: 0
Ok next time I'll use something other than a Dremel tool... I bet it'll take longer than 10 minutes to groove an engine using a hacksaw and jeweler's file though.
I'm not using the Powre Lynz... since I want to get the fuel to vaporize inside the combustion chamber anyway. The grooves seem to be doing a fine job of that now, judging by how smooth and quiet the engine runs..
My car has been the testbed for a number of fuel economy ideas and the grooves are just another test. Even just for performance and driveability the grooves would be worth it, but I'm really hoping for some high fuel economy too.
Jeremiah
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Re:Groove shape
Date: 2006/07/03 18:27
By: ehamilton
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Karma: 0
When I saw the name Jeremiah my memory was prodded. Could this be the Jeremiah that made all those GEET posts a few years ago? Yes. I enjoyed them but could not bring myself to put that much effort into those ideas. This is quite different. I modified my Briggs and Stratton powered lawn mower a couple weeks ago with three grooves. I had to adjust the fixed governor spring down a bit. I no longer smell like exhaust when I am done mowing the lawn. The hot starts are much easier. This was quite a surprise as I was quite careless and spent about 1/2 hour on the whole job including R&R of the head. I have never done anything so easy that made so much difference before in my life.
A couple days ago I put some grooves in a Tecumseh 49 cc 2-stroke piston because I could not get to the head of the monolithic block. The results are not as dramatic as with the flat head engines. I might go a little larger with the grooves, maybe not.
I am curious about your Geo mileage. You are starting with an efficient engine to begin with. I had been wondering about this engine for other reasons when I saw your post. These are used in ultralight planes where smooth operation is beneficial.
Ernie Hamilton
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Re:Groove shape
Date: 2006/07/03 23:58
By: jsenner
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Karma: 0
Yeah, I'm the guy who probably drove more GEET powered miles than almost anyone except Paul Pantone... and proved that it got worse mileage in general than factory fuel injection could.
I'm still trying to get my car back up to last summer's mileage. It was getting 53-55 mpg last summer regularly. It appears that it can now repeat or possibly exceed that with the grooves, and I'll find out in a couple weeks when my next long trip comes up. I almost never fill the tank before I only have a gallon or two left... usually 400-500 miles per tank... so it takes me time to get mileage tests.
I'm experiencing clean burn like I never saw before, as well as the engine running considerably cooler, and way smooth low RPM operation. I've got the best of both worlds almost, with the combination of grooves and a long header... good torque from 1500-6500 rpm. It's pretty nice! But I've got some trouble with pinging because of a high C/R.
This is a different engine, but the same GEET powered car, minus the GEET, of course!
Jeremiah
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Re:Groove shape
Date: 2006/07/04 21:36
By: mpgmike
Status:
Karma: 4
Hey Somender, in India, doesn't GEET mean "Flower Dance" or "Smell of a flower"?
Mike
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Re:Groove shape
Date: 2006/07/05 22:30
By: ehamilton
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Karma: 0
Mixing torque grind cams and high compression can be a bit challenging. I did that once myself. I don't think it is genarlly recommended. Retarding the camshaft a bit might alleviate some of the pinging but you will then lose some of the low end torque. It is all a trade off. Ernie H
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Re:Groove shape
Date: 2006/07/05 22:54
By: jsenner
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Karma: 0
In this case, the head package I got is normally sold with 10.5:1 C/R and I only upped that to 11:1. I think it's working pretty good considering. Eventually I'll probably have it tuned where it runs decent.
The most recent tank of fuel did 52 mpg averaged over 450 miles. This tank consisted of many cold starts and 0-60 test runs with lots of redline shifts, plus in-town and Interstate driving. Not too bad considering, I think. It even lost about a cup of fuel to head removal and fuel line replacement.
Jeremiah
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Re:Groove shape
Date: 2006/07/05 23:29
By: Silverback
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Karma: 0
ehamilton wrote: Mixing torque grind cams and high compression can be a bit challenging. I did that once myself. I don't think it is genarlly recommended. Retarding the camshaft a bit might alleviate some of the pinging but you will then lose some of the low end torque. It is all a trade off. Ernie H
High compressions and short durations both bump cylinder pressure below the torque peak, making it hard to control detonation, but probably the best way around it is to dramatically tighten the LSA to generate some overlap and kill some of that cylinder pressure. With that setup you can still have your bottom end and even better midrange but you will loose some top end.
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Re:Groove shape
Date: 2006/07/09 18:52
By: somender
Status:
Karma: 4
JSENNER
Send us details and your project will be featured in the Test Results Section. that goes for MPG Mike too, and anyone else who has definitive findings after performing Groovy mods.
This idea is really taking off. People all over the world are asking more questions, but as of yet, no Big Fish asking (just lurking around based upon the webstats) or taking the 'Bait'.
We'd love to know what's going on in those underground labs! :)
An article from England is coming soon!!!
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