You need to understand the real meaning of the term " choked flow " in relation to the 2T cycle first.
So read the paper I have attached, as this is the best I have seen on the science involved.
In reality most people have a misunderstanding of the effect,in that once the local gas velocity is sonic, no increase in VELOCITY can occur.
But , the mass flow rate CAN increase, under the conditions stated..
I went thru this exercise a while ago in relation to determining if sonic conditions occurred when using a nozzle in the Ex duct, or in the tailpipe.
Short answer is that if a normal sized venturi or duct/pipe restriction are used, the local velocity does not exceed Mach 1.
I found that in the sim ( where determining the local gas velocity at any point is trivial ) as soon as you approached sonic conditions, power went down dramatically.
From this I concluded that the energy required to create sonic flow is very high, and this appears to detract very quickly from the energy being used in the pipe for expansion,compression
and stuffing.
My logic may be faulty, but the end result of sonic conditions for sure are not.
And one small point in relation to blowdown.
Port stagger, front to rear, uses the remnant blowdown pressure ratio at the transfer opening point, to affect the scavenging regime.
Remember, no flow can occur until the pressure ratio at the port face goes negative, thus until the pressure in the duct exceeds the cylinder pressure, flow will stall, or in a worst case
it will be reversed back down the transfer that opens first.
This short moment in crankshaft rotation, is enough to affect the distance traveled by each transfer stream in turn,and is why a KZ2 engine needs the A port opening first - as with no PV
it needs the " natural " effect of that regime to widen the powerband.
An Aprilia on the other hand uses reverse stagger, with the B/C ports opening first, that has the effect of boosting peak and overev power by its change in the scavenging pattern, along with the bigger STA
available from the wide B port being high as well.
Ive got a thing thats unique and new.To prove it I'll have the last laugh on you.Cause instead of one head I got two.And you know two heads are better than one.
They cover both; the variation of the crankcase volume during one crankshaft revolution should not exceed the permissible cylinder capacity, so both suction and primary compression are coupled to piston displacement. In addition, any mechanical device that creates positive boost, is forbidden (an exhaust pipe does that, but it is not considered a mechanical device).
so in theory it would be "legal" to add let's say a solenoid operated diaphragma to the crankcase that makes the volume larger at high revs and smaller at low revs (or something similar that has the same effects). has anyone ever tried that ?
No free lunch, any sort of activation device that changes the case vol is no different to a variable Ex port valve setup - not legal.
Same with the 24/7 reed concept, maybe they would allow a spring loaded open/close setup, but any form of servo that was rpm
driven, be it electrical or mechanical, is out.
Ive got a thing thats unique and new.To prove it I'll have the last laugh on you.Cause instead of one head I got two.And you know two heads are better than one.
No free lunch, any sort of activation device that changes the case vol is no different to a variable Ex port valve setup - not legal.
Same with the 24/7 reed concept, maybe they would allow a spring loaded open/close setup, but any form of servo that was rpm
driven, be it electrical or mechanical, is out.
But Wob why stick to rules like the FIM ones when they just ban the two stroke anyway?
I am not meaning kart controlling bodies.
Kinky is using a feather. Perverted is using the whole chicken
A bit of rubbish has been bouncing around in the head. I will be able to clean that up, no problems.
Drive side main bearing pretty stuffed, even some of the balls were flaking. The bike was sounding pretty rough for the last couple of hundred dyno pulls.
The bike was blowing a lot of smoke and drinking its gearbox oil. Chambers had this problem before and replacing the oil seal didn't do any good but after he replaced his drive side bearing all the oil burning problems stopped. We put it down to the crank flopping about and making the drive side oil seal act like a pump.
The piston has cracked but I expect to be able to salvage it with a dab of weld.
All in all not bad after several seasons of track time and hours on the dyno.
You're going to reuse that Piston TZ? I suppose it is a bucket.
That bearing really chewed itself up huh! Were they the phenolic cage bearings?
Great little engines huh
I thought we were talking about the Modena and the Ryger and using differing technology to make more power in the only racing class ( CIK - KZ2 )
that has newly homologated engines still being produced every year.
Sure in GP racing all this stuff may be fine , but someone would still need to reverse the FIMs aversion to 2T - and this may in fact be possible if the technology was available
to all ( forget the patent rights ) and it could be shown conclusively to be more eco friendlier than a racing 4T ( not that they are at all ).
Ive got a thing thats unique and new.To prove it I'll have the last laugh on you.Cause instead of one head I got two.And you know two heads are better than one.
You're going to reuse that Piston TZ? I suppose it is a bucket. That bearing really chewed itself up huh! Were they the phenolic cage bearings? Great little engines huh
Yes, I am going to re use the piston, not so much because its a "Bucket" but more because I can and to tease the 4T boys who would have to buy an expensive replacement with no guarantee of reliability.
It was a double row, self aligning phenolic caged bearing that was brought second hand with a bunch of others off Ebay for $1 and gave good service in the Beasts engine for lots of seasons before finally retiring.
Yep, the 70-80's Suzuki GP125 is a great little engine, , cheap as to make race winning power with, same as the other 2T's that run at the front.
I thought we were talking about the Modena and the Ryger and using differing technology to make more power in the only racing class ( CIK - KZ2 )
that has newly homologated engines still being produced every year.
Sure in GP racing all this stuff may be fine , but someone would still need to reverse the FIMs aversion to 2T - and this may in fact be possible if the technology was available
to all ( forget the patent rights ) and it could be shown conclusively to be more eco friendlier than a racing 4T ( not that they are at all ).
Nah F the FIM.
Why bother with them at all? Remember the good of days before the Bernie Ecclestone's the Dornas and co got involved in motorsport.
Produce a product that people can support and people will get involved.
Kinky is using a feather. Perverted is using the whole chicken
this evenings adventure. just as things were going great the damn tungsten fell out of the collet. i couldnt believe it. melted it to shit and the party was over. as it was my only 3/32" collet it was time for plan B. install 1/16" collet and continue on
Yes, I am going to re use the piston, not so much because its a "Bucket" but more because I can and to tease the 4T boys who would have to buy an expensive replacement with no guarantee of reliability.
It was a double row, self aligning phenolic caged bearing that was brought second hand with a bunch of others off Ebay for $1 and gave good service in the Beasts engine for lots of seasons before finally retiring.
Yep, the 70-80's Suzuki GP125 is a great little engine, , cheap as to make race winning power with, same as the other 2T's that run at the front.
Heck yeah. If you lightly centre punch the piston the divets will be the riding surface which will flatten over and you will effectivly decrease the piston clearance so it will be like new. You can't decrease the ring end gap but if you stretch the ring out you will increase the dynamic tension and that helped Charles Atlas kick sand in the face of weaklings on the beach , or so the back of my comic books used to say. Welding rod is expensive, some JB weld should fix that right up if you are just putting it on the inside which is cooled by the gas should be fine you can trust me.
Don't you look at my accountant.
He's the only one I've got.
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Originally Posted by Frits Overmars
I suppose it is a bucket.
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