Combustion Chamber Science - Pocket Bike Forum - Mini Bikes
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post #1 of 35 (permalink) Old 08-22-2007 Thread Starter
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Combustion Chamber Science

In reference to the originating thread "Dome Inserts", some interests, and conflicts of interests alike, were raised that concerns a modification to a dome. Seems this mod is for the gear head tweakers that like to squeeze every single worth out of an engine. Yep, that would be me.

If your a newby, please get some experience before going further, or at least wait and see what some veteran tweakers have done. Hopefully from here on, I/they will post thier methods and such. Just make sure you have made your decision on your own, therefore responsible for your own actions. This is where I will make reference to a remark that BMY said, "KISS = Keep It Simple Stupid", because for some people he is correct, some people should just leave this subject alone. Now that I got that out of the way...

Some people know that I/my family build circle dirt modifieds and drag racing engines. On accident, and late last night I brought up the dome mod to my father's cylinder head tech. He said "Oh, for two strokes, oh hell dude Ive done that mod even to 4 stroke engines in 4-wheelers as well as jet ski engines AND some of the higher end drag racing heads." I was a little in awe, and then he told of a website to look at before I asked any more questions. Appearantly he is right, this modification to domes are old and effective news.

Ive read the site corner to corner, quite interesting. Here is the site. http://pesn.com/2005/10/13/9600187_D...tion_Chambers/
Read it, chew on it, there you go......Do what you will.

jd
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post #2 of 35 (permalink) Old 08-23-2007
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Re: Combustion Chamber Science

I knew I'd seen this somewhere else before. Great reporter work, there Torquey.

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post #3 of 35 (permalink) Old 08-23-2007
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Re: Combustion Chamber Science

I usually don't say much anymore but This Deserves A good Thanks
Always love Good Reading. This ***** like **** for the brain.
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A+++
and 3 gold stars

Last edited by Aeon2; 08-23-2007 at 05:53 PM.
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post #4 of 35 (permalink) Old 08-23-2007
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Re: Combustion Chamber Science

Pretty cool stuff.
One thing i noticed though is that where it says "how do I cut a groove?" It recommends milling the head to go from roughly 8.5:1 to roughly 10:1 compression. This alone would give a slight power increase across the boardregardless of any grooves, channels, etc.
FWIW, I asked Joe Mondello about this and he just giggled a bit. I personally don't know what is so funny about it, but he said he would let me know when I talk to him next week.

Geico.....so easy, a caveman can do it!
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post #5 of 35 (permalink) Old 08-23-2007
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Re: Combustion Chamber Science

yes please let us know as i'm thinking of doing this mod and what is so funny about it
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post #6 of 35 (permalink) Old 08-23-2007
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Re: Combustion Chamber Science

thats a really sweet article
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post #7 of 35 (permalink) Old 08-23-2007
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Re: Combustion Chamber Science

yeah I noticed that about compression and adjusting the squish to what he says is already what we are doing to improve low end and better burn
In a week or so il try it on one my Cag motors for ****s and giggles
since the head is like 20$
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post #8 of 35 (permalink) Old 08-23-2007
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Re: Combustion Chamber Science

I have been searching and haven't found much of anything later than Dec of 2005 about this. I am sure it is out there, I just haven't found it yet.

And still no dyno specs. And I don't mean hp specs, I have seen them used to measure fuel consumption as well. (In lbs per hour not mpg).

Geico.....so easy, a caveman can do it!
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post #9 of 35 (permalink) Old 08-23-2007
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Re: Combustion Chamber Science

lbs of fuel per hour what's the formula for that one ?
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Re: Combustion Chamber Science

Its a term usually associated with dyno work as the dyno doesn't go anywhere. Its just for relative fuel consumption at full power. Similar to what they use in aviation. I've just bought a new cutter for the mill that will be useful for cutting these "channels". You can be sure I'll be trying this and soon. I rarely discount any claims (unless they truly are ridiculous) before trying them myself. (I remember trashing a clutch with the "aluminum shoes" that didn't quite fulfil their claims as being the next great white hope!)

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Re: Combustion Chamber Science

Thought-provoking article. In theory it could provide some improvement to combustion speed and efficiency. I think that radial curved groove would create a swirling pattern better than the straight grooves most of the reported tests used. I agree that changing the CR at the same time makes the results invalid unless the CR change was only enough to exactly counteract the slight drop caused by cutting the grooves.

Still, it would be interesting to try on my 15:1 CAG engine using three equally spaced curved grooves. Domes are cheap enough

Cheers,

red
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Re: Combustion Chamber Science

I've modified one of my big bore dome caps with a groove as detailed in the above article and the following photo is how it came out. I've only put in the one groove because of the small size of the head. Pending results from this head design, I'll be using a narrower angled cutter to introduce more grooves at a later date. I've designated this head as the BMY-SS-XP. SS is for Somender Singh, the inventor of the groovy chamber design, and XP for experimental. I'll keep you posted with results. My first thoughts of groove alignment within the cylinder are directly above the exhaust port, as this is where detonation is most likely to start from.
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Re: Combustion Chamber Science

Quote:
Originally Posted by bike mad yank View Post
I've modified one of my big bore dome caps with a groove as detailed in the above article and the following photo is how it came out. I've only put in the one groove because of the small size of the head. Pending results from this head design, I'll be using a narrower angled cutter to introduce more grooves at a later date. I've designated this head as the BMY-SS-XP. SS is for Somender Singh, the inventor of the groovy chamber design, and XP for experimental. I'll keep you posted with results. My first thoughts of groove alignment within the cylinder are directly above the exhaust port, as this is where detonation is most likely to start from.
dude if it wasn't for me telling you guys about this mod you would have never known about it. i've been doing this to domes for 5yrs from gas boat engines to rc glow motors and pocket bike motors. i an't looking for a pat on the back but because of you i got banned for 3 days. because you're always shooting down my ideas. but remeber this what comes around goes around yank dude.

Last edited by stuch; 09-07-2007 at 10:10 PM.
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Re: Combustion Chamber Science

Stuch, you haven't learned much about people in the 42 years you been on this earth, have you. "what goes around comes around"? Is that some kind of threat. Grow up dude. There's plenty of rage forums on the internet. If you're looking for a pat on the back, join a support group for anger management. As for now, you'll stay on my ignore list until you've got something sensible to say and can treat people with the respect you think you've earned.

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Re: Combustion Chamber Science

I'm rather curious to see how this eventually works out for those who try it. I had seen this concept quite awhile ago but never tried it as I couldn't find any results. It can be rather hard to convince people to try something new on an expensive engine.
If I can get some spare combustion chamber domes for my CAG engine I will give this a shot.

I'm no expert so take my opinions / information with a grain of salt. I could just be dribbling *@#!

Thank you for taking the time to read my post.
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Re: Combustion Chamber Science

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Originally Posted by bike mad yank View Post
Stuch, you haven't learned much about people in the 42 years you been on this earth, have you. "what goes around comes around"? Is that some kind of threat. Grow up dude. There's plenty of rage forums on the internet. If you're looking for a pat on the back, join a support group for anger management. As for now, you'll stay on my ignore list until you've got something sensible to say and can treat people with the respect you think you've earned.
yank all i know is you're some dude on the other side of the pond and i don't care what you have to say either way. all i know is this, i'am not trying to threaten you it's just the law of the land put out enough smack it comes back to you. if i recall you said this should be on an extreme fourm site trying to shoot down my idea now you're trying that idea. that sort of being a bigot. i might add i'am in the people business for 20yrs and i own business that produces 3.8 million dollars a yr for the last 18yrs. it's just you i'am having trouble with. and thats fine. and i bet after you see the gains you'll be doing this setup to every p/b motor you have. AND IT'S ALL BECAUSE I TOLD IT TO YOU. and because of that i already WON the fight......

Last edited by stuch; 09-08-2007 at 12:45 PM.
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Re: Combustion Chamber Science

Quote:
Originally Posted by bike mad yank View Post
I've modified one of my big bore dome caps with a groove as detailed in the above article and the following photo is how it came out. I've only put in the one groove because of the small size of the head. Pending results from this head design, I'll be using a narrower angled cutter to introduce more grooves at a later date. I've designated this head as the BMY-SS-XP. SS is for Somender Singh, the inventor of the groovy chamber design, and XP for experimental. I'll keep you posted with results. My first thoughts of groove alignment within the cylinder are directly above the exhaust port, as this is where detonation is most likely to start from.
Neat to see someone trying this out for research. Hope you have some power gains.

Banshee - Polini Race Crank, Polini reeds, BZM coil, D1 pipe, 7 : 65 gearing, 19mm Dellorto PHBG DS, ported cylinder matched to crank case, BZM water pump, (new)ADA Head kit w/15:1 dome., Blata 2.5 - Broken exhaust, last but not least 99' Mustang Cobra Procharged at 8psi 420rwhp/427rwtq
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Re: Combustion Chamber Science

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Originally Posted by stuch View Post
yank all i know is you're some dude on the other side of the pond and i don't care what you have to say either way. all i know is this, i'am not trying to threaten you it's just the law of the land put out enough smack it comes back to you. if i recall you said this should be on an extreme fourm site trying to shoot down my idea now you're trying that idea. that sort of being a bigot. i might add i'am in the people business for 20yrs and i own business that produces 3.8 million dollars a yr for the last 18yrs. it's just you i'am having trouble with. and thats fine. and i bet after you see the gains you'll be doing this setup to every p/b motor you have. AND IT'S ALL BECAUSE I TOLD IT TO YOU. and because of that i already WON the fight......

Stuch...not to bust your balls, but it isn't your idea. That^^^ post kinda reflects that it is, which is not entirely true. Now having said that, even though I personally won't be using this mod, I think it is cool that you thought to cross it over from the r/c field. Kudos to you.

And I personally look forward to the results BMY posts, good, bad, or indifferent.

Geico.....so easy, a caveman can do it!
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Re: Combustion Chamber Science

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Originally Posted by cutlasskel View Post
Stuch...not to bust your balls, but it isn't your idea. That^^^ post kinda reflects that it is, which is not entirely true. Now having said that, even though I personally won't be using this mod, I think it is cool that you thought to cross it over from the r/c field. Kudos to you.

And I personally look forward to the results BMY posts, good, bad, or indifferent.
thanks but i never said i invented the idea i just said i was the guy who brought the info to light on the site and have seen gains from this idea. and if other mods work for me i'll be inlighting you fellows again.
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Re: Combustion Chamber Science

by the way bmy's dome is different then mine i use the 3 grove pattern 1mm deep with a star pattern and i put it towards the boost port side of the motor. but to tell you the truth if bmy's design turns out to be good i'll be trying it in the future. don't get me wrong i give credit where credit is due....
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