I found this idea while looking for info about piston design. Has anyone heard or tried this? It is the idea of machining a small groove into the cylinder head at the squish pads from the combustion chamber to the cylinder wall. Usually one or two grooves that point toward the spark plug. This is to provide better ignition of the fuel in the squish band during the ignition stroke. And to create turbulance in the combustion chamber for better mixing and complete burn while also helping to remove exhaust from these areas during the exhaust stroke.

The performance result is less fuel used, lower temps, noticeable reduction of knocking/pinging, smooth idle and more low end torque (when lugging the engine at low rpm).

There were pictures of the cylinder head's carbon build up pattern before and after the mod. The afters are amazingly clean and even. Drag racers seem to using this on their 10 sec. muscle cars.

I may give this a try while I have my head off. Our squish pad area is relatively small, but mine were covered with carbon. The piston's carbon build up fallowed the pattern of these areas too. It was exactly what the site's theory describes as the issue.

you can find more info by searching squish grooves or somender Singh (the guy that patented the idea, but shares how to diy). Turbobricks.com and mpgresearch.com have a few threads with pics as well.

I know that this is likely to be flamed, so please leave it alone if you don't have anything constructive to contribute. Especially if you don't know what squish or quench area is.

 

Some definitions and a useful calculator. http://www.rbracing-rsr.com/squishcalc1.html

 

Interesting idea. My question would be, if this makes a measurable difference, why have auto manufacturers not caught on? Maybe too difficult to mass produce heads with this feature...

dan

 

It could be that this modification won't make much of a difference unless you're running a lot of boost or have made other significant engine modifications.

As you pointed out, engineers don't leave a lot on the table when they're designing engines, which is why things like capacitor-equipped spark plug wires, higher-voltage coils, and intake "vortex" devices don't show much of a benefit on stock engines. If devices like this produced significant gains in stock engines without unacceptable tradeoffs (e.g. noise, pollution, longevity), they would have been included in the design in the first place.

 

Interesting idea but don't most modern engines try and induce a swirl in the combustion chamber to more efficiently fill and empty the area during the intake and exhaust strokes? It would seem these grooves in a modern engine design would interfere with this somewhat. I'll have to do more research on it.

 

That's sort of how it works. Different manufacturers use it for different reasons too. For example, Honda uses the swirl in the Insight in order to ignite an overall lean mixture. The swirl caused the fuel particles to gather toward the center of the cylinder, making it easier for the spark to ignite them. Those engines run upwards of 21 or 22:1 A/F ratio at times.

In a race engine, you don't want to swirl. You want to mix the air and fuel evenly. The idea here is to make the flow on the intake stroke as laminar as possible (really not that laminar at all) and then use the compression stroke to create lots of turbulence that mixes the air and fuel. You have to do all this while minimizing hotspots in the cylinder. It's not an easy task.

 

Speaking of gooves; this came off a 325i.

 

Seems a little beyond me, but if done correctly it could be benificial.

 

[quote=k-huevo;1848032]Speaking of gooves; this came off a 325i.
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That looks like a metric mechanic head... or a copy. Not exactly the same idea. The somender grooves are meant to more completely burn the fuel that is contained in the quench or squish area. That helps with mpg's, carbon build up, idle quality/speed and power (usually lost by the wasted fuel and the space that it takes up). Other power increases possible by being able to reduce the ignition timing due to a faster, more complete burn and a reduction in octaine requirement. At least that is what I got from it.

I will let you know how it goes after I get my engine back together.

 

I was always of the belief that such grooving was more beneficial to heads that have very large quench areas, mainly 2-valve OHV designs. 4-valve pentroof chambers dont usually have quite as much quench area, depending on design.

 

[quote=Greatbear;1851051]I was always of the belief that such grooving was more beneficial to heads that have very large quench areas, mainly 2-valve OHV designs. 4-valve pentroof chambers dont usually have quite as much quench area, depending on design.[/qu

I agree with that, but there were reports of benefits on heads with smaller pads than ours. Also, the quench pads on my head were heaviliy carboned and the burn/carbon pattern matched exactly the theory that is described.

I have my head off and felt inspired. I don't expect much in terms of performance, but it may pan out with the right tuning, etc... If I get a MPG gain that would be nice too! To me it makes sense, but I know that science isn't always that intuitive.

 

Some of this is a little above my head, technically speaking, but it sounds like a solid idea as far as I can tell. Do let us know what the outcome is.

 

I grooved my head while I had it off to do a mini rebuild. It should be back together this week. I'll post my thoughts once it is broken in. Some pics to fallow.

Khuevo,
I had an m6 head off last week and it had groove in it similar to the picture you posted. The basically looks like ares, but there were grooves cut between the valves, starting at the sparkplug and working thier way out. They were finer than than ones in the pic though. I was very suprised when I saw them. These are not the same as what I did. Mine are more like channels to the squish areas. I'll see if I can get pics of the old head.

 

Ah, there's a couple pics in my gallery. If you can post them here, please do.

 

Here you go...



...nice job. Let us know if you notice anything different.

BTW, how's the OBX diff holding up?

 

Hey, thanks for putting up the pics. I am anxious to see if anything noticeble happens. I'm waiting on a few parts still . Another weekend job that takes two months.

I wanted to clean up the ports and chambers a little, but decided to wait just to be sure where the improvements are coming from.

The OBX diff is working great! It really is impressive, especially after driving an open diff mcs once I got used to the OBX. I did beat up the second gear synchro after losing a slave cylinder, but that is another story.

 

I put everything back together last night. Wiseco pistons, fresh rod bearings and the grooved head. Other than grooving it, I only dissassembled and cleaned the head. I was tempted to clean up the casting but decided to leave it alone for comparison.

Only about 150 miles and it drives amazing. It keeps getting stronger and very smooth. I can't imagine that the new pistons and rings added that much power. Remember that the three remaining cylinders had less than 4% leakdown and compression at the higher end of the specs when I took it apart.

I started getting on it a little on the way home tonight. I rolled onto the throttle at 3k rpm in first and the tires just lit up. Same thing the next few lights, rolled on a little easeir, but just couldn't accellerate and keep traction. That's with the LSD too. A little smoke from the rear, so maybe I'll ease up until the rings are fully seated.

I haven't driven it enough to make a final judgement. For now, I can't believe how strong it is. Infact, I have been driving a BMW 335i for the last few months and I thought that even if I got a little gain from the rebuild I wouldn't notice after driving the twin turbo. Wrong, it has never been stronger. I keep thinking, really, no really, it actually works.

I should be ready to dyno it january. I'll report the numbers and my avg. mpg then. For now I have a new o2 sensor to install (the old one has 117k on it)and a tune up to finish. MAybe there's still a little left to get out of it.