"I finally stumbled on an article with drawings":http://pesn.com/2005/10/13/9600187_Design_to_Improve_Turbulence_in_Combustion_Chambers/
Remember Singh? And his Groovy heads?
Re: Remember Singh? And his Groovy heads?
wow! chaos math for two stroke?
Re: Remember Singh? And his Groovy heads?
Don't reveal my secrets. I've been there and havn't come back. it does work on mopeds, and it works well.
Re: Remember Singh? And his Groovy heads?
FOr realZ? what did you do, e-mail me if you don't want to share with the group, but I am very interested. I haven't CNC'd my head yet but was thinking of changing my drawings to accommodate being groovy
Re: Remember Singh? And his Groovy heads?
I put a milled 50cc head on my RGD cyl only to find it had too much compresssion so to correct this I went ahead and put grooves in. The engine blew from unrelated reasons but I just got it back together with new piston last night and that head and plan to light it off today. I'll post here after another good run. It ran fine before with the head
Re: Remember Singh? And his Groovy heads?
I did this:
to one of my puch heads, and it actually runs better. you can't see the carbon on my head though. I polished it to reflect heat in the combustion chamber, and reduce carbon.
Re: Remember Singh? And his Groovy heads?
Do it. you won't regret it.
Re: Remember Singh? And his Groovy heads?
Where is the notch in relation to intake/exhaust?
Re: Remember Singh? And his Groovy heads?
Pure GARBAGE!!!!!!!!!!!!!!!!!!!!!!!!!!
Squish is as old as engines.
His holes and slots do absolutely NOTHING.
Directed Squish is better than Squish. You want a circular pattern in the squish. That is why intake and exhaust valves are not always symmetric.
In two strokes, you don't want the circular pattern. In 2 strokes you want to keep the intake from going out the exhaust. That is why the transfers point to the back of the cylinder.
Don
Re: Remember Singh? And his Groovy heads?
how does intake and exhaust port placement have anything to do with this?
what is "directed squish"?
have you actually tried this?
Re: Remember Singh? And his Groovy heads?
Put the groove opposite of the exhaust.
Re: Remember Singh? And his Groovy heads?
that little groove doesn't do shit but muck up yer squishband. see pattern in carbon.
Re: Remember Singh? And his Groovy heads?
Turbulence is good however those grooves are wrong, they drop your compression , create hotspots for preignition and interrupt the flame front ,preventing a smooth complete burn path . It's possible it creates a dual flame pattern that hits eachother for turbulence but that would creates turbulence after the flame starts and interfere with exhaust extraction.
The only thing I know that actually works is the offset fin with a matching groove in the head - This is use in Model airplane engines - look at any Fox or McCoy .35 glowplug controline engine. It creates Turbulence and keeps the exhaust flow moving in one direction without interrupting the intake flowpath. Early McCulloch Mac 110 or Wens used piston wedges cast in their pistons . But never short shallow grooves. Just My 2 cents.
Re: Remember Singh? And his Groovy heads?
It seems to me, based on the lit presented, that Singh's ideas haven't been tested. Hence all the back and forth. To second what Sean said, it seems like intake/exhaust ports don't even come into play for most of this.
The whole point of his design is to interrupt the standard burn path by causing turbulence which allows for the distribution of more flame fronts and quicker combustion. One effect of speeding up this combustion is preventing preigntion. The dude actually came up with this in order to kill preigntion on the hi comp bikes he was building. The photo above shows it at least causes a different pattern of ignition.
I found the second page of the popular science article (at the bottom of the linked page) to be a better explanation of what he's trying to do. Reading Jennings pgs. 22-28 (especially 23) helped too.
Re: Remember Singh? And his Groovy heads?
After I did some more googling I found out quite a few people have made these mods and are quite happy, from VW forums to Camaro forums. There are people claiming increased power in low RPM situation, people are claiming lesser fuel consumption too. But there are an equal amount of nay-sayers too.
Re: Remember Singh? And his Groovy heads?
"metro owners too":http://www.jeremiahsviolins.com/grooves.htm
Re: Remember Singh? And his Groovy heads?
i remember this coming up a few years back, as usual with this sort of pseudo-scientific stuff the data is sparse, the research methods are ambiguous, and most of the people with strong opinions are basing it on seat-of-the-pants measurement.
a few observations i've made
#1: Factory race teams in MotoGP have spent billions of dollars squeezing every last drop of power from the 2 stroke engine, towards the end of the 2t era, they were approaching theoretical limits for 2 stroke efficiency. They have used elaborate fluid modeling software, and i'm sure tried every possible permutation of squish band shape possible. I've never seen a pro race engine with anything like this. I find it hard to believe some mechanic dude in india with a dremel in his garage discovered something missed by the best engine designers in the world.
#2: Turbulence in a 2 stroke combustion chamber is on the order of crazy. We use something called a reynolds number in fluid mechanics to describe the ratio of viscous effects in a fluid to the velocity of motion. If you think about it, water moving at 20 mph is going to have much more disturbance in it than air moving at 20 mph. The reynolds number in a combustion chamber is so far off the charts, that any increase or decrease would have a negligible effect on combustion efficiency. Especially in a two stroke where crankcase pumping and transfer ports turbulate the air even further.
#3: Flame propagation is the one element which i think could be significantly affected by the grooves. With the groove pushing fresh gas towards the exhaust port side, you might see better combustion late into the power stroke, higher temps in the blowdown exhaust.
the head, as pictured, looks like it has timing problems or is being run with shitty oil, that much carbon buildup isnt normal, it should be a much lighter color, esp if running syn.
Want to post in this forum? We'd love to have you join the discussion, but first: