converging squish angle

[registered user]

anybody heard of this being done on purpose ?  tried to see what the affects would be using torq soft but it wont let you input a degree value less than 0

[WINDYCITYJOHN400]

Trinity ships out lots of motor kits with converging squish angles. That's why they blow O-rings out of the motor like you fed it warm week old egg salad. 

 

It's just bad MmmKay

[RadarRacing]

Thats not a correct way to build a motor. You want the fuel air charge going toward the spark not being away. Trinity still does some motors jacked up.

[registered user]

im wondering what it would do to the msv. and would it put a hot spot near the edge of the bore

[WINDYCITYJOHN400]

Pressure wave heading towards O-ring, heat forced to piston edges, blow by forces on rings.....it's just a long list if bad.....

[m671054]

Im not sure how to word this correctly but here goes. In the squish band how does increasing the angle affect power ouput. example if your at .045" on the outer edge and .055" on the inside of say a 10mm wide band vs. .045"-.065" or parralel at .045 all the way. also explain proper terminology

[possum]

Good questions. Waiting on bhq experts to chime in.

[camatv]

you have to at least to me. think about whats going on inside the motor.  now NOONE can tell EXACTINGLY whats going on in there, or we wouldn't have those special fancy dancy camera's to make all kinds of neato flame front pictures.  you can tho look at burn patterns and look at dome burn patterns also....   looking at dome patterns made realize a bunch of stuff and change the shape of the domes i was playing with.  along with a few other things that TO ME AT LEAST made a lot of sense 

 

as far as i understand it the spark creates a burn wave and if that burn wave is not mixed well it dose not travel well. and you dont get a 100% burn.  most motors burn rate or effeciency is horrible.  lots of fuel is wasted to attempt to keep deto down and cool off the insides of the motor.  the squish band creates a huge WOOSH inside the cylinder and shoves the fuel air charge into the middle of the bore.  it also creates a ton of turbulence that keeps the fuel mix "mixxed" instead of separating into fuel/ air.   the angle and width has the effect of creating that turbulence and creating the effect on the mix.  MSV numbers i dont really like my self ( i KNOW i'm going to get a bunch of shit on this one)  the programs i have played with i can have 35 differnt shapes and they ALL result in the same MSV numbers.  the shapes i have come up with i cannot program into them because the shape cannot be made with straight lines. and one radius line  i also fugred out creating more turbulence in differnt places i think can make a lesser fuel do more and burn more creating less of a chance for deto.   these similar shapes can also create more of a burn for alcohol also. ( at least what i THINK is going on in the motors i do for me)

 

to me dome design should be used to create the most turbulence without separating the fuel mix, the most cooling effect without creating to cold OR to HOT of a piston surface.  and also a way to raise the efficiency of the rate of burn or flame front and attempt to burn 100% of the charge..  

[blowit]

I think most have this covered.  A divergence angle in the head would effectively trap unburnable fuel at the outside circumference of the piston.  It will also cause a pressure spike at TDC which likely is the reason for head seal failures.  The idea of design in the modern squish band 2 stroke head is in an effort to increase the volatility of the fuel/air charge before combustion.  Two things do that, pressure, and heat.  Physics laws dictate that the "rate" of compression of a gas has an affect on the heating of the gas. 

 

 

It is just a numbers game but I have explained many times that there is a reason yur ignition system timing has a "curve" and is not linear to flat.  PIston acceleration and rate of gas compression have a large affect on the burn rate of the charge thus the reason to change when the combustion event starts thus optimizing when max cylinder pressures are obtained. 

[m671054]

Which one is tighter on the outside? diverging or converging

[m671054]

Also post any good books or computer programs to learn about msv, dome profiles, compression ratio calcs etc.

[registered user]

Which one is tighter on the outside? diverging or converging

 

 

it all depends how your looking at it. but diverging meens to open and converging meens to narrow. most heads that ive seen are either paralell or diverge as they got toward the center. search on google brotha

 

< diverge

> converge

 

make sense?

 

gp blair book design and simulation of 2stroke is probly the best one out there

[m671054]

I think most have this covered. A divergence angle in the head would effectively trap unburnable fuel at the outside circumference of the piston. It will also cause a pressure spike at TDC which likely is the reason for head seal failures.

so then thid statement is incorrect? convergance would cause this?