Squish angles, turbulence and detonation...

Blaner · 04-20-2010, 07:40 PM

Hey, one for the pros to answer...
Im researching squish angles and how it directly affects max squish velocity. I am looking to modify my blasters head to get better efficiency from its combustion process.
When cutting the squish areas angle, do we cut it at the same angle as the piston dome angle? surely this would allow the mixture to be squished into the combustion dome at the same rate as the piston compresses the mixture thus preventing detonation? would it benefit me at all to cut the squish area at an greater angle than that of the piston dome or is a waste of time and turbulence?

From what I understand, skimming the head in order to increase compression without compentsating with adjusting squish bands we will end up with detonation?

Also, what is the highest CORRECTED compression ration that could be run on 95octane fuel

Lastly, is it best to polish my piston crown and the entire combustion chamber? will a surface left slightly rough generate greater turbulence or do smooth surfaces do it better?

OConnor Racing · 04-22-2010, 12:54 PM

If you’re trying to make a head with a squish band that works, you’re going to have to cut about .130 off of the sealing surface. Cut the squish angle @ 11 – 12 degrees and then start cutting the combustion chamber until you get the cc’s your looking for. A hemispherical chamber with a 50% band works well. The compressed thickness of the gasket is about .030 and the piston could be in any number of places when it’s @ TDC. Shoot for about .045 from the top of the piston to the top of the cylinder head to be on the safe side. You’re probably going to end up cutting .010 - .020 off of the top of the cylinder. Graham Bell explains this very well in his book. Just search his name and two stroke tuning. Short read but very helpful.

Blaner · 04-22-2010, 05:22 PM

Ok, those are the figures ive been working with according to the Mcdizzy site. it gives me the required squish thicknesses and so on. Id love to use a software package to calculate it myself instead of using someone elses data but as a student, they a bit pricey! Thanks for your input, i seem to be on the right track!

Anyone else have anything to add??

OConnor Racing · 04-22-2010, 06:04 PM

2 Stroke Tuners Handbook by Gordon Jennings

http://www.kreidler.nl/artikelen/per...raham-bell.pdf

I built a Mac Dizzy engine a couple of years ago and still own it. Works pretty good and a bunch better than stock. Chech out the two links I sent you. This should help. The Dizzy porting is kind of mild.

Little-J · 04-23-2010, 06:00 AM

yeah, I know what you mean about the software.. I would love to model my engine on ricardo pulse but it costs about 1000$ to get the licence and then you still have to figure out how to use it.. what are you studying?

Blaner · 04-23-2010, 06:04 PM

Thanks guys, im actually studying a Bsc in geosciences, i did a bit of mechanical engineering a few years ago,but found i prefer keeping that sort of thing as a hobby, the maths seemed to overshadow the actual concept and it was killing my interest in the topic, as a hobby its far more enjoyable! what can i say... I like rocks

brandoz28 · 04-23-2010, 06:06 PM

i know what you mean man......i lost a lot of interest in playing guitar when i was teaching 25+ lessons a week. but damn do i miss that money

xjma · 04-23-2010, 07:14 PM

Quote:

Originally Posted by Blaner

Thanks guys, im actually studying a Bsc in geosciences, i did a bit of mechanical engineering a few years ago,but found i prefer keeping that sort of thing as a hobby, the maths seemed to overshadow the actual concept and it was killing my interest in the topic, as a hobby its far more enjoyable! what can i say... I like rocks

What's up man, I've got an associates in ME and while going for my BS decided I really didn't want to be an actual ME, so now I'm a hydrogeologist....I get to apply math to the real world! Geology is the shit, keep it up man! Must be sweet to be studying geo in South Africa!!

04-20-2010, 07:40 PM	#1 (permalink)
Blaner Can't Stop, Won't Stop! Join Date: Mar 2008 Location: East London, South Africa Age: 27 Posts: 2,998 Rep Power: 108 Reputation:	Squish angles, turbulence and detonation... Hey, one for the pros to answer... Im researching squish angles and how it directly affects max squish velocity. I am looking to modify my blasters head to get better efficiency from its combustion process. When cutting the squish areas angle, do we cut it at the same angle as the piston dome angle? surely this would allow the mixture to be squished into the combustion dome at the same rate as the piston compresses the mixture thus preventing detonation? would it benefit me at all to cut the squish area at an greater angle than that of the piston dome or is a waste of time and turbulence? From what I understand, skimming the head in order to increase compression without compentsating with adjusting squish bands we will end up with detonation? Also, what is the highest CORRECTED compression ration that could be run on 95octane fuel Lastly, is it best to polish my piston crown and the entire combustion chamber? will a surface left slightly rough generate greater turbulence or do smooth surfaces do it better? __________________ When In Doubt - Hit The Power Band 2000 Blaster SUSPENSION: Durablue banshee 2+2 axle; Full Flight YFZ450 +2 complete front suspension; Banshee front brake calipers; Raptor 660 front spindles and disks; Honda 400ex rear shock +100mm custom swingarm; Kawasaki GPZ400 rear hydraulic brake system; YFZ450 alloy rims; 22" Kenda Klaws MOTOR: FMF Fatty gold series and Powercore II; 68mm bore-Wiseco ProLite (Currently running OEM Cast); Vesrah Conrod; Boyesen Reeds; Auxillary boost ports drilled; Ported and polished barrel; Polished crankcase; Rechambered head, 1mm base plate spacer (Currently suspended), 30mm OKO-NO GO! (Back to Trusty Mikuni 26mm); NoToil Filter. Drivelines Heavy duty clutch. BODY: Meshed front grill; Factory Effex Graphics Kit; Aluminiun boot scuff guards; ProTaper Hi-Rise bars; Raptor 700 Steering Stem; Custom HDPE frame guard

04-22-2010, 12:54 PM	#2 (permalink)
OConnor Racing Can't Stop, Won't Stop! Join Date: Dec 2009 Location: CT Age: 51 Posts: 1,311 Rep Power: 86 Reputation:	Re: Squish angles, turbulence and detonation... If you’re trying to make a head with a squish band that works, you’re going to have to cut about .130 off of the sealing surface. Cut the squish angle @ 11 – 12 degrees and then start cutting the combustion chamber until you get the cc’s your looking for. A hemispherical chamber with a 50% band works well. The compressed thickness of the gasket is about .030 and the piston could be in any number of places when it’s @ TDC. Shoot for about .045 from the top of the piston to the top of the cylinder head to be on the safe side. You’re probably going to end up cutting .010 - .020 off of the top of the cylinder. Graham Bell explains this very well in his book. Just search his name and two stroke tuning. Short read but very helpful.

04-22-2010, 05:22 PM	#3 (permalink)
Blaner Can't Stop, Won't Stop! Join Date: Mar 2008 Location: East London, South Africa Age: 27 Posts: 2,998 Rep Power: 108 Reputation:	Re: Squish angles, turbulence and detonation... Ok, those are the figures ive been working with according to the Mcdizzy site. it gives me the required squish thicknesses and so on. Id love to use a software package to calculate it myself instead of using someone elses data but as a student, they a bit pricey! Thanks for your input, i seem to be on the right track! Anyone else have anything to add?? __________________ When In Doubt - Hit The Power Band 2000 Blaster SUSPENSION: Durablue banshee 2+2 axle; Full Flight YFZ450 +2 complete front suspension; Banshee front brake calipers; Raptor 660 front spindles and disks; Honda 400ex rear shock +100mm custom swingarm; Kawasaki GPZ400 rear hydraulic brake system; YFZ450 alloy rims; 22" Kenda Klaws MOTOR: FMF Fatty gold series and Powercore II; 68mm bore-Wiseco ProLite (Currently running OEM Cast); Vesrah Conrod; Boyesen Reeds; Auxillary boost ports drilled; Ported and polished barrel; Polished crankcase; Rechambered head, 1mm base plate spacer (Currently suspended), 30mm OKO-NO GO! (Back to Trusty Mikuni 26mm); NoToil Filter. Drivelines Heavy duty clutch. BODY: Meshed front grill; Factory Effex Graphics Kit; Aluminiun boot scuff guards; ProTaper Hi-Rise bars; Raptor 700 Steering Stem; Custom HDPE frame guard

04-22-2010, 06:04 PM	#4 (permalink)
OConnor Racing Can't Stop, Won't Stop! Join Date: Dec 2009 Location: CT Age: 51 Posts: 1,311 Rep Power: 86 Reputation:	Re: Squish angles, turbulence and detonation... 2 Stroke Tuners Handbook by Gordon Jennings http://www.kreidler.nl/artikelen/per...raham-bell.pdf I built a Mac Dizzy engine a couple of years ago and still own it. Works pretty good and a bunch better than stock. Chech out the two links I sent you. This should help. The Dizzy porting is kind of mild.

04-23-2010, 06:00 AM	#5 (permalink)
Little-J Advanced Join Date: Nov 2009 Location: stuck at work :( designing engines : ) Age: 25 Posts: 171 Rep Power: 45 Reputation:	Re: Squish angles, turbulence and detonation... yeah, I know what you mean about the software.. I would love to model my engine on ricardo pulse but it costs about 1000$ to get the licence and then you still have to figure out how to use it.. what are you studying? __________________ 2004 Blaster, 66.5mm bore, helluva porting job, paul turner pipe, HotRods con-rod, Koyo C4 spec main bearings, fat boy silencer, twin air filter, renthal chainwheels and DID o ring chain, oil pump and tank removed, Lone Star Axcalibar +2 axle, Lone Star +2 a arms, Gold Speed Nerf Bars, Renthal High Bar, Reiger custom made suspension front and rear, Douglas 8" rears, and Douglas Front rims, ITP HoleShot rear tires, Maxxis Razr MX front tires, Custom (homeBrew) wiring harness with only the bare essentials, CEET contra red graphics and seat cover, Home brew stator plate +1 timing, braided front and rear brake lines, A arm skid plates, Motion pro throttle and clutch cables, and.. homebrew LED two scale rear light with brake switches on the front and rear brake.

04-23-2010, 06:04 PM	#6 (permalink)
Blaner Can't Stop, Won't Stop! Join Date: Mar 2008 Location: East London, South Africa Age: 27 Posts: 2,998 Rep Power: 108 Reputation:	Re: Squish angles, turbulence and detonation... Thanks guys, im actually studying a Bsc in geosciences, i did a bit of mechanical engineering a few years ago,but found i prefer keeping that sort of thing as a hobby, the maths seemed to overshadow the actual concept and it was killing my interest in the topic, as a hobby its far more enjoyable! what can i say... I like rocks __________________ When In Doubt - Hit The Power Band 2000 Blaster SUSPENSION: Durablue banshee 2+2 axle; Full Flight YFZ450 +2 complete front suspension; Banshee front brake calipers; Raptor 660 front spindles and disks; Honda 400ex rear shock +100mm custom swingarm; Kawasaki GPZ400 rear hydraulic brake system; YFZ450 alloy rims; 22" Kenda Klaws MOTOR: FMF Fatty gold series and Powercore II; 68mm bore-Wiseco ProLite (Currently running OEM Cast); Vesrah Conrod; Boyesen Reeds; Auxillary boost ports drilled; Ported and polished barrel; Polished crankcase; Rechambered head, 1mm base plate spacer (Currently suspended), 30mm OKO-NO GO! (Back to Trusty Mikuni 26mm); NoToil Filter. Drivelines Heavy duty clutch. BODY: Meshed front grill; Factory Effex Graphics Kit; Aluminiun boot scuff guards; ProTaper Hi-Rise bars; Raptor 700 Steering Stem; Custom HDPE frame guard

04-23-2010, 06:06 PM	#7 (permalink)
brandoz28 Can't Stop, Won't Stop! Join Date: Sep 2009 Location: Iowa Age: 25 Posts: 10,766 Rep Power: 166 Reputation:	Re: Squish angles, turbulence and detonation... i know what you mean man......i lost a lot of interest in playing guitar when i was teaching 25+ lessons a week. but damn do i miss that money __________________ F7 Pipe, Powercore2 silencer, 14/40 gearing, Banshee rear brake, Wiseco 67.50 piston, Wiseco crank assembly, vf3 reeds, +4 timing mod, PE Clutch basket, 30mm OKO Carb, Oil injection delete, Uni air filter, AC Racing front bumper, '86 250R rear shock, Works Triple Rates with remote rezzies, DG nerfs *WILDCARD powered*

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