16X Technical observations
i think he means on its side like my avatar... lower center of gravity, spark plugs on top, intake and exhaust ports on the bottom.
i've been thinking bout this myself, it would allow more freedom for variable intake length tuning since you could "wrap" the intake runners around the engine towards the top...
i've been thinking bout this myself, it would allow more freedom for variable intake length tuning since you could "wrap" the intake runners around the engine towards the top...
Longer runners are only really useful at lower RPM, for max power you want short runners anyway..
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From: Suwanee, GA
The intake runners would be straight shot and move up and down to increase/decrease velocity/flow. Individual throttle bodies.
What would be the best MAF set up?
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From: Toronto, Canada
Its already best setup, don't forget you'll have to bolt up to the trans.
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Last edited by Renesis_8; Sep 11, 2011 at 02:39 PM.
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Going WAAAY back here (and digging up an old thread but hey, it's relevant), Mazmart mentioned that the rotary has some unique obstacles that come with switching to DI that piston engines don't. Perhaps we could use our collective minds to sort out what those may be and how Mazda may be approaching the fixes for them. DI seems to be what kept the 16X from coming out earlier as it needs a LOT of refinement and discovery before Mazda can place the injectors properly.
Specifically, I'm thinking the tendency of rotaries to have fuel stick to the wall of the working chamber and the need for better charge mixing are what's holding the design back. There's a couple options here:
1) You can put the injectors at the top of the engine perpendicular to the air flow (like the 16x shown to the public). This would encourage the charge to mix but I imagine you would have trouble with the fuel sticking to the rotor face negating any benefits of DI. You'd just run over-rich as rotaries do now with low NOx numbers and high HC numbers.
2) You can angle the injectors so they send the fuel somewhat parallel to the direction to the moving air. This would keep fuel off the walls avoiding sticking but then you discourage mixing of the charge so you get less power.
I think the big thing to glean from the two options here is that there are two extremes, both unsatisfactory and a huge selection of angles of orientation relative to the chamber walls. Now no doubt there is a sweet spot in between the two extremes where mixing for increased power is optimized as is the reduction of fuel droplets on the walls. But I bet it's damned finicky to find especially since there's a third variable involved: placement of the injectors as some others have mentioned. It suddenly seems very obvious why the project director said the 16x has proven the concept but there's a lot of refinements to be made. A LOT of trial and error is involved. Frankly my head wants to explode at the amount of fluid dynamics involved.
Specifically, I'm thinking the tendency of rotaries to have fuel stick to the wall of the working chamber and the need for better charge mixing are what's holding the design back. There's a couple options here:
1) You can put the injectors at the top of the engine perpendicular to the air flow (like the 16x shown to the public). This would encourage the charge to mix but I imagine you would have trouble with the fuel sticking to the rotor face negating any benefits of DI. You'd just run over-rich as rotaries do now with low NOx numbers and high HC numbers.
2) You can angle the injectors so they send the fuel somewhat parallel to the direction to the moving air. This would keep fuel off the walls avoiding sticking but then you discourage mixing of the charge so you get less power.
I think the big thing to glean from the two options here is that there are two extremes, both unsatisfactory and a huge selection of angles of orientation relative to the chamber walls. Now no doubt there is a sweet spot in between the two extremes where mixing for increased power is optimized as is the reduction of fuel droplets on the walls. But I bet it's damned finicky to find especially since there's a third variable involved: placement of the injectors as some others have mentioned. It suddenly seems very obvious why the project director said the 16x has proven the concept but there's a lot of refinements to be made. A LOT of trial and error is involved. Frankly my head wants to explode at the amount of fluid dynamics involved.
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The problem is, that unlike a piston engine, your chamber is moving away from the injectors, so it's very diffcult to get a stratified charge around the spark plugs, if you spray the fuel in where the plugs are, you're limited to spraying straight towards to rotor face so you don't get a very good charge mix and you get some sat on the face.
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The problem is, that unlike a piston engine, your chamber is moving away from the injectors, so it's very diffcult to get a stratified charge around the spark plugs, if you spray the fuel in where the plugs are, you're limited to spraying straight towards to rotor face so you don't get a very good charge mix and you get some sat on the face.
http://protonet.org/doc/index.htm
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Going WAAAY back here (and digging up an old thread but hey, it's relevant), Mazmart mentioned that the rotary has some unique obstacles that come with switching to DI that piston engines don't. Perhaps we could use our collective minds to sort out what those may be and how Mazda may be approaching the fixes for them. DI seems to be what kept the 16X from coming out earlier as it needs a LOT of refinement and discovery before Mazda can place the injectors properly.
Specifically, I'm thinking the tendency of rotaries to have fuel stick to the wall of the working chamber and the need for better charge mixing are what's holding the design back. There's a couple options here:
1) You can put the injectors at the top of the engine perpendicular to the air flow (like the 16x shown to the public). This would encourage the charge to mix but I imagine you would have trouble with the fuel sticking to the rotor face negating any benefits of DI. You'd just run over-rich as rotaries do now with low NOx numbers and high HC numbers.
2) You can angle the injectors so they send the fuel somewhat parallel to the direction to the moving air. This would keep fuel off the walls avoiding sticking but then you discourage mixing of the charge so you get less power.
I think the big thing to glean from the two options here is that there are two extremes, both unsatisfactory and a huge selection of angles of orientation relative to the chamber walls. Now no doubt there is a sweet spot in between the two extremes where mixing for increased power is optimized as is the reduction of fuel droplets on the walls. But I bet it's damned finicky to find especially since there's a third variable involved: placement of the injectors as some others have mentioned. It suddenly seems very obvious why the project director said the 16x has proven the concept but there's a lot of refinements to be made. A LOT of trial and error is involved. Frankly my head wants to explode at the amount of fluid dynamics involved.
Specifically, I'm thinking the tendency of rotaries to have fuel stick to the wall of the working chamber and the need for better charge mixing are what's holding the design back. There's a couple options here:
1) You can put the injectors at the top of the engine perpendicular to the air flow (like the 16x shown to the public). This would encourage the charge to mix but I imagine you would have trouble with the fuel sticking to the rotor face negating any benefits of DI. You'd just run over-rich as rotaries do now with low NOx numbers and high HC numbers.
2) You can angle the injectors so they send the fuel somewhat parallel to the direction to the moving air. This would keep fuel off the walls avoiding sticking but then you discourage mixing of the charge so you get less power.
I think the big thing to glean from the two options here is that there are two extremes, both unsatisfactory and a huge selection of angles of orientation relative to the chamber walls. Now no doubt there is a sweet spot in between the two extremes where mixing for increased power is optimized as is the reduction of fuel droplets on the walls. But I bet it's damned finicky to find especially since there's a third variable involved: placement of the injectors as some others have mentioned. It suddenly seems very obvious why the project director said the 16x has proven the concept but there's a lot of refinements to be made. A LOT of trial and error is involved. Frankly my head wants to explode at the amount of fluid dynamics involved.
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Its all just assumption. This all was already developed and tested - Curtiss Wright, John Deere, NASA, NSU-Audi, Mazda... All the informations are out there...
http://protonet.org/doc/index.htm
http://protonet.org/doc/index.htm
Absolutely worth mentioning and I just completely forgot about it when I made my little list. Thanks.
Going WAAAY back here (and digging up an old thread but hey, it's relevant), Mazmart mentioned that the rotary has some unique obstacles that come with switching to DI that piston engines don't. Perhaps we could use our collective minds to sort out what those may be and how Mazda may be approaching the fixes for them. DI seems to be what kept the 16X from coming out earlier as it needs a LOT of refinement and discovery before Mazda can place the injectors properly.
but outside the box, who knows.
hope to see the rotary continue..
beers
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From: Houston
the piston folks have enough trouble with DI i can't imagine how mazda could find a solution. you can't allow the fuel to touch the wall of the rotor or the chamber: emission problem
the piston fix this by air guiding or wall guiding or (old piston head design guiding)
though can't mazda take advantage of the cooler intake phase of the rotor housing and have more liberty with how the fuel is injected? or port the intake differently to take advantage of the rotor's spinning motion to further mix the A/F mixture.
stratified combustion is out of the question for rotary though.. hard enough for piston.. how the hell for a rotor.
the piston fix this by air guiding or wall guiding or (old piston head design guiding)
though can't mazda take advantage of the cooler intake phase of the rotor housing and have more liberty with how the fuel is injected? or port the intake differently to take advantage of the rotor's spinning motion to further mix the A/F mixture.
stratified combustion is out of the question for rotary though.. hard enough for piston.. how the hell for a rotor.
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From: Houston
They've been testing DI in rotaries (by Mazda) for over 30 years and almost to the beginning of the rotary concept by others. There have been many different iterations including some very ingenious ones. I assure you there is nothing that anyone here can think of that hasn't been tried before. It's not as easy as it sounds. A version from the 80's that they tried, which achieved stratefied charge, and keep in mind this was before the complex ecu controls we have today, was so efficient that it didn't need a throttlebody. It was completely run off of varying the amount of fuel just like in a diesel engine. That's how well they made it work. The problem was that the exhaust ran too cool, much like a diesel engine does, which didn't allow them to hit cat light off temperature. The way emissions rules are written in the US, you can't have a gasoline powered car here without a working cat. It doesn't matter if it can pass emissions without it. That's irrelevant. It has to have a working cat. That's politicians for you! In order to get this exhaust temp, they had to throttle the intake. This also killed the benefits they got from that DI setup.
There are tons of SAE papers out there on the rotary. At the end of the day you are going to find that the 2 biggest things holding the rotary back are politicians and accountants. The engineers have had great ideas for decades. Ideas that would work wonderfully. However the accountants don't think they are cheap enough and the politicians don't understand how things actually work outside of their imaginary world so we don't see many innovations. We only see the ones that fit within their narrow scope of acceptable standards.
There are tons of SAE papers out there on the rotary. At the end of the day you are going to find that the 2 biggest things holding the rotary back are politicians and accountants. The engineers have had great ideas for decades. Ideas that would work wonderfully. However the accountants don't think they are cheap enough and the politicians don't understand how things actually work outside of their imaginary world so we don't see many innovations. We only see the ones that fit within their narrow scope of acceptable standards.
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But in other papers,(and believe this is just fraction of RE development) there are things which has been evaluated in computer programs ---->developed and tested in real research engine.
This was pinnacle of Wankel engine development in regards of thermal efficiency - if you know turbo rotary with BSFC of .375 lb.HP/Hour, let me know
Only interesting thing about 16x is new geometry in regards of decreased surface area/volume ratio at TDC and faster/better propagation of flame front in all directions with all associated benefits, mainly combustion stability at leaner AFRs...
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he problem was that the exhaust ran too cool, much like a diesel engine does, which didn't allow them to hit cat light off temperature. The way emissions rules are written in the US, you can't have a gasoline powered car here without a working cat. It doesn't matter if it can pass emissions without it. That's irrelevant. It has to have a working cat. That's politicians for you! In order to get this exhaust temp, they had to throttle the intake. This also killed the benefits they got from that DI setup.
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No offense intended but I just don't buy that. If that was all it took, then Mazda could have produced some totally useless, hollowed out cats with no platinum in them and stuck them on the exhausts. Bye bye backpressure concerns, law passed and emissions were a non-issue anyways given your account. Yet it never happened. As for blaming bean counters, I'm right with you there but I truly question this particular instance's validity.
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