Somender Grooves Revisited

[Eric Hodges]

I am new to the Samba and I am resurrecting the head grooves topic because it got solidly bashed some time ago and I believe its benefits were overlooked. The groove is not to develop more horsepower nor is it able to be properly evaluated with a dyno. The grooves make the low speed (idle and off idle) behavior of the engine more solid and the combustion efficiency better. My goal is to get better mileage with my car and have a sweet running engine.

I had a 'new' 1600 from a crapo rebuilder that had a hole in the case at the oil gallery. JB Weld was tried over and over to no avail. During the 300 mile life of this engine I replaced the Solex with a Progressive out of sheer frustration. The Solex leaked/squirted out the accel. pump tube, idled high or low or not at all, and blackened my plugs at the lean-best idle setting. The progressive, after rejetting from aircooled.net instructions, ran fine.

I put in another rebuilt engine before researching thoroughly here on The Samba and may have got taken. It is a 1776 with stock everything, it runs, it had new cylinders and not a valve job but a paint job. I cc'd the heads (53cc) and cut two Somender grooves .062 deep and .125 wide on each hole. I calculate the static compression at 8.3:1, a bit high, but perfect for the grooves.

I warmed the new engine, I did not pay too much attention to new parts break in because I was not sure there were that many. I twisted the distributor to get it to fire and let it run at high idle. After a moment of running that way, I set the timing to 7 deg advance and had to turn the idle mixture screw in from 2.25 turns out to .75 turns out. WAY LEAN! and it ran fine.

The carb is not jetted for this size engine and the idle jet is way too big, but the drive around the block showed a very strong pull off idle and electric-motor smoothness where there should be a bit of vibration. I am very pleased. Unfortunately, I broke my leg later that day and can't drive a stickshift for a few more weeks. The next step is proper jetting and break-in before I know more.

I believe our aircooled, ancient technology motors are good candidates for this groove because the low compression and need for heat control in the heads can benefit from this well-bashed technology.

[vwracerdave]

You talking about this thread? http://www.thesamba.com/vw/forum/viewtopic.php?t=407679&highlight=groove+head+combustion+chamber

It was BS back then and still is today

If it worked I guarentee every new car sold today would use it.
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[Eric Hodges]

Yup, that's the one. There are other equally negative blogs that vividly share the 'bad theory' and 'everybody would be doing it' but that is not my desire. The theory probably can't be prooved without some very costly equipment and a team of researchers. Not my bag.

I have put the grooves into my heads and will post results as they become available. So far, there seems to be a difference. I can measure mileage and I can provide driving impressions that will be valid, independent of the theory. And, after all, don't we all want a well behaved engine and a pleasurable driving experience? That is the joy of the hobby along with the satisfaction of making those upgrades and enhancing the performance. I have no illusions of making a dragracer or getting 50mpg out of a 1776.

Have you made the car that you want to drive?

[jbbugs]

It's nice to see somebody ACTUALLY try it out to see if it works and find out for themselves under some real world testing before condemning it.
Keep us posted.
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[RockCrusher]

I always thought the idea had merit. It is still a squish/quench issue. We pretty much ALL agree that tight deck height is a good thing in general. What I wonder is do the grooves speed up the air coming out in that region or actually slow it down? Like you get a bunch of velocity coming off the quench surfaces and then you introduce these grooves which would seem to slow the velocity just locally so you get some other directional turbulence as the hi-velocity collapses around the hi pressure area of slower moving gases. Make any sense?
I don't see the grooves being nearly as effective (if they are in the 1st place) in large deck engines. Hard to say exactly what they are doing in reality. It would seem important to me to test before and after gas analysis. What are the NOX results? That would tell a lot about whether it is an up front effect or a residual effect. Funny that there is a patent on the idea but no one has stepped up to do any real proof or dis-proof with controlled testing.

RC
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[mark tucker]

I think it would depend on the grooves and how they are positioned& depth.but just taking a die grinder and grooving your chambers might sound like you are a mad scientist ,well you just might be one. and how will you determine weather it did any good? butt dyno ??or dyno 10 motors and do exzactly the same mod to each of them and re check the out come.if it helps 2 hp hear and hurts 3 hp there you have probably gone the wrong way, but that all depends on where the add power is and where the loss of power is,and the affect on detination.

[tncsparky]

did you take pictures of the grooves?
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[Eric Hodges]

I am glad to see there is at least some interest in the grooves. I believe, from reading about it, that the grooves force a jet of gas/air mix out of the squish area toward the sparkplug. The mixture will take the path of least resistance under pressure and stir up the combustion chamber, mixing the gas/air combo more completely. When the plug fires, it then ignites the chamber with a more smooth flame front producing an even burn. As the piston goes down, the flame front travels back up the groove igniting the combustables in the relatively confined squish area, providing the whole chamber with a more complete burn. Whew, neat theory anyway.

The chevy guys (automotivebreath) have shown clean piston tops and clean combustion chambers after running the engine for a while, implying the burn travels into the entire chamber. He also reports clean motor oil after 2000-3000 miles of use, implying the unburned fuel in the chamber is minimized and does not contaminate the oil.

Somender Singh suggests the squish should be .060in and the chevy guys get good results with less, like .045in. My piston is .060 down the hole and the step in the head is .020in and I put the grooves below the step. My deck height is larger than both .080in but it is also a VW with low compression.

There's the detail but the real test is yet to come. 12 days before the cast comes off, Yeah.
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[jesus_chrysler]

Look at it this way. put two sheets of plywood on top of each other then with two people put the top one off as fast as you can. It tries to suck the bottom one up with it. Now put several grooves down the plywood and try again. It will not do it nearly as bad.

Think of what your piston has to do when it gets to within .060" of your head and pull away again 20-100 times a second!!! Seems plausable to me.

I put the grooves in my heads. What the hell. its worth a shot! 2276 turbo. I will post when I know more.
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[CLKWRK]

I have these grooves in my heads too, you can barely see them in the bottom of the pic. (sorry its the best pic I could find of them)
Not sure if they do much but I do run .040" deck, its a turbo 2332.
They seem to be aimed at the plug

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[DarthWeber]

I'll throw this in here, not as a point of contention, but just to cover another technological aspect. Money aside, I think the Super Squishy pistons have more to offer in terms of torque potential, cooler head temps and better fuel mileage.
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[Eric Hodges]

I don'think the head groove vs the piston groove makes much of a difference. Just my opinion, but the jet blast seems like the key to the benefit. The blast across the combustion chamber makes up for the poor distribution of the mixture and stirs the fuel / air into a more homogenious combination.

The effect I hope to achieve is a reliable, low rpm boom to make up for the long intake and fuel falling out into droplets. The benefit should be better torque, less fuel used and less difference between hiway and city mileage. I will report findings as soon as I can use gas and clutch.
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[modok]

I'm a little confused, how you gonna do a back to back test if you didn't do the "before" part?
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[Bruce]

[Eric Hodges]

This is going to be more fun than I thought. The before part of my test is a stock VW that has big bore kit, like they used to say. No big cam, turbo or stroker. No pro-ported heads nor delusions of 7000 rpm. My research on the Samba here concludes that a typical VW will get 25 -30 mpg, maybe less maybe more. My goal is to get over 30 mpg driving it like a real car, keeping up with modern traffic and to have it be snappy and fun. Quantify that.

As for the big car companies, I dont presume for a moment that the engineering department that gave us runaway acceleration would be interested in mileage improvements. The American trio that gifted us with 50k mile transmissions would not dare consider someone else's patent enployed in their cars. Were it not for the Japanese invasion in the 70's, we may still be driving 12 mpg behemoths. Oh wait we still are.

The grooves I'm trying just might be crazy enough to work and I refuse to believe the only viable technology comes from the big guys. They don't port heads either. Look up Larry Widmar and his soft heads.
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'74 Super, worn, becoming DD

[miniman82]

[theastronaut]

[mark tucker]

I agree,and the big grooves? so what is funneling the mix into them??it is already squishing out.. and my 2332,2028&1874 all got better than 30 mpg.were not slow,ran just fine, no groovy lines in the chambers.just a few in the paint. I think you may see more by doing some in the intakes, but you need to know whats going on in there before starting and get each port mirrored on each head. vanes in ports have been hear since the 70's possiably the 60's. chevy had d ports,c ports, e ports. and the infoumus vortex port that was like a stairway to heaven ,but was very restrictive ,but it worked good at lower rpm.some super stock hemi cars have a modified e port intake port. the chrysler small b;locks had a snake running down the port.(it was a turd and needed to be removed but they must of thought it did something or it would not of been there for 30+ years of production.) so give it a whirl(pun intended) and see what you can do.

[jesus_chrysler]

Eric I'm not against your thinking but when it comes to dicussion on this forum your better off giving up the argument until you have something to prove it with otherwise you will have lots of nay sayers against you.

I am trying lots of new and different things on my motor but I know they would not be well accepted in this forum so I am keeping my mouth shut until I have evidence to back it up.

Do it and let us know how it pans out man!

By the way I know 2 stroke sled guys that swear by it.
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My collection:
73 Standard 2276 turbo EFI
63 Single cab
67 11 Window
70 Charger 440
76 Kawasaki H1 triple 2stroke
06 Chopped HD

[RockCrusher]

I did it to my flat head 11hp Briggs just because I wanted to along with porting and multi angle valve job and a small bump in compression.....and a VW stinger on the exhaust. Haven't fired it up yet but I hope it wakes up my little Snapper.
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I will be happy to speak to anyone who has a serious inquiry (meaning real potential business for RC enterprises) or a parts order. Due to machining noise causing missed calls all calls will be returned promptly.
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