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Managed to tweak the check valve to the point where vacuum doesn't suck w/m into the engine anymore. Did a 500km round trip to the snow on Tuesday and only used one liter of mix for the whole trip. Almost 500kms on one tank of gas wasn't too bad either!
Also:
Was listening to one of Rob Dahms videos last night and realised the effect of cooling and providing fuel down the APV runners may be a ton more beneficial than I realised. There is definitely the potential for hot spots within the combustion chamber caused by fuel-less APV air.
I highly doubt that any part of air volume stays unmixed with other parts of it .. by the time its time to combust, the air/fuel mixture is very homogenous. The air is VERY turbulent in the combustion chamber especially while on boost.
I highly doubt that any part of air volume stays unmixed with other parts of it .. by the time its time to combust, the air/fuel mixture is very homogenous. The air is VERY turbulent in the combustion chamber especially while on boost.
Surely it's always better to get the mix as homogenous as possible before compression - isn't that a basic fundamental of engine design? It's why Mazda have injectors on ports on either side of the rotor! Do any piston engines you know of, not put fuel through every intake valve? Apart from DI of course.
all those "swirl" generators ect are for low load and restricted airflow. When its under 70-80% load or higher, the speeds dooring compression are very very high (thus mixing as well).. in some engines approaching 100m/s (ant there it is only vertical compression, not moving of the whole volume like on a wankel). Its impossible to have non homogenous mixture. Many high perf 4Cyl 16V engines have intake manifold runners at different angles to head ports and injectors are usually biased.
I suppose you saw some "combustion" marks and how they are washed in some area and in some they are clean. This has nothing to do with how good and equal the combustion is, it is a consequence of washing from intake stroke.
see ere a two smoke piston..and that is called "wash pattern".
there’s a reason Mazda doesn’t put fuel in the APV
1. the barrel isn’t on/off like the SSV and it’s long even from the manifold face to the port opening.
2. where does the remaining fuel go when the barrel is closed
there’s a similar potential issue with water injection ahead of the manifold split to the APVs, which is why I wouldn’t do it that way
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I hear ya ..... where I have it, it goes to the other ports when the APV closes.
And ...it's not like I'm pouring fuel/water down there either ...... it's half of the total w/m requirement (so less than 5% of the total fuel requirement) . Even then not all of the flow from that nozzle will go into the APVs .
May as well just pour in fuel through the garden hose then ...lol
Well .. at high loads you might as well (if you're on nitromethane)..
As for normal engines.. its an argument in bad faith..
A hose doesn't atomise the fuel.. and will thus not mix the fuel with air.. but even if we say ½ of air gets all the fuel and the other ½ is dry. The ½ with the fuel has atomised fuel in double concentration but its still same atomisation as it would be if the fuel was split equally between air..
And Its exactly the same as when the the injector is flowing for ⅒ of the time that the port is open.. there all the fuel is delivered in ⅒ of the air, and all the rest of the air is "dry" untill mixed in combustion chamber.
Also with DI engines which have much more complete burn than any port injected especially at low load, where the fuel has much less time to mix.. and is delivered in few very small volume parts and the mixing is again due to the turbulence in the combustion chamber..
Onl 5% of fuel is your WI target ? That is very low amount.. based on the ones with high success system they are up to 30%
As for normal engines.. its an argument in bad faith..
Not at all ..... to make a point I was pointing to the ridiculous ..... which often helps some people understand how small details can matter.
A hose doesn't atomise the fuel.. and will thus not mix the fuel with air.. but even if we say ½ of air gets all the fuel and the other ½ is dry. The ½ with the fuel has atomised fuel in double concentration but its still same atomisation as it would be if the fuel was split equally between air..
And Its exactly the same as when the the injector is flowing for ⅒ of the time that the port is open.. there all the fuel is delivered in ⅒ of the air, and all the rest of the air is "dry" untill mixed in combustion chamber.
Also with DI engines which have much more complete burn than any port injected especially at low load, where the fuel has much less time to mix.. and is delivered in few very small volume parts and the mixing is again due to the turbulence in the combustion chamber.
To me it makes sense to do what you can to get it done before compression ..... Mazda thought so too when they switched to four injectors on the S2 and made sure each side got fuel.
Only 5% of fuel is your WI target ? That is very low amount.. based on the ones with high success system they are up to 30%
No . Aiming for total water/meth between 13-25% depending on rpm etc . But that's both nozzles (and only one is over the APV runner entrance). And as I mentioned before it's likely that not all from that nozzle goes to the APVs. So approx. 5% of the fluid (as water/methanol) is going to APV ports at least and approx.12% at most.
But you do realise that even if all ports are getting perfect ratio fuel to air, it is still not all the time that the fuel is flowing. So the mixture going in to the engine still wont have a uniform mixture.. as depending on DC of FI they will be only for a percentage of the time/volume of air.
But you do realise that even if all ports are getting perfect ratio fuel to air, it is still not all the time that the fuel is flowing. So the mixture going in to the engine still wont have a uniform mixture.. as depending on DC of FI they will be only for a percentage of the time/volume of air.
Sure I take your point ... but still, some effort is made to get it to either side and spread it out as much as is practical to do so.
Got braver and took it to 10psi today ... (creeps a little still, to 10.8 at redline)
couple of things
* Spoolup def. seems better
* Peak power seems to be very strong (considering I have the apvs restricted)
* torque is virtually flat the whole way - love this!
* don't seem to be losing any power anywhere from the water/meth
Why are you restricting the APV ? I recall seeing it in another thread but cant fid it quickly. Doe the turbo fall of the efficiency for lower boost with less intake restriction ? as power is a function of MAF not boost, I see no other reason to restrict flow (and raise boost) .
Why are you restricting the APV ? I recall seeing it in another thread but cant fid it quickly. Doe the turbo fall of the efficiency for lower boost with less intake restriction ? as power is a function of MAF not boost, I see no other reason to restrict flow (and raise boost) .
Mostly to allow me to run more boost lower down the rpm range without getting too close to the exhaust flow limitations up top that can lead to detonation. As pointed out in the thread I made on the subject ...the same thing could be better achieved by just lowering boost up top. Seeing as i don't have that ability with my current setup ... I choose to restrict the APV instead.
Not an issue for anyone running under 380ish whp though.
Thinking out "loud" so please correct me if im wrong on something.
Boost is outcome of the intake restrictions of the flow on intake and driving power in the exhaust.
Assuming driving power is constant (same amount of exhaust gasses and flow ect as consequence of same engine power) it only varies on the intake
The turbo is producing 10psi of boost to move 400g/s (just for some numbers sake) du to restriction (flow and available volume)..
if you would reduce the restriction it would still "only" push 400g/s but now at 7psi (assuming the flow restriction equates to 3psi) and most likely less heat, thus more efficient combustion with less knock probability (the ultimate limit of power :D ).
I must be missing something. Are you producing more power if you don't have the restriction with same boost control settings , is it that than a wastegate restriction not being able to unload the engine?
Thinking out "loud" so please correct me if im wrong on something.
Boost is outcome of the intake restrictions of the flow on intake and driving power in the exhaust.
Assuming driving power is constant (same amount of exhaust gasses and flow ect as consequence of same engine power) it only varies on the intake
The turbo is producing 10psi of boost to move 400g/s (just for some numbers sake) du to restriction (flow and available volume)..
if you would reduce the restriction it would still "only" push 400g/s but now at 7psi (assuming the flow restriction equates to 3psi) and most likely less heat, thus more efficient combustion with less knock probability (the ultimate limit of power :D ).
I must be missing something. Are you producing more power if you don't have the restriction with same boost control settings , is it that than a wastegate restriction not being able to unload the engine?
First thing I'd say is that, at 10 psi it doesn't matter. There is no risk, so I could remove the restriction without consequence. The effect of doing so at the same EBC settings would be, same boost but more power and more mass flow above 6500 rpm. To the point where torque is actually higher past 6500 than it is earlier on.
However, at say 15psi, without the restrictor, there is enough flow/backpressure/heat past 6500 to tip the engine into a dangerous state where it's on a knife edge and could detonate. I can't stress this enough ....preventing this situation outweighs any other efficiency considerations by a massive margin!
By putting the restrictor in, I'm pulling that mass flow down after 6500 and eliminating that knife edge situation. This is now enabling me to still run 15psi early in rpm range without having that risk later in rpms.
Net result is a near dead flat torque curve and an increased safety margin.
Again, same thing could be done without the restrictor if I had ability to control boost by rpm. And it's been pointed out that dropping boost past 6500 would be a better way to achieve it, for the reasons you stated above.
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Again, same thing could be done without the restrictor if I had ability to control boost by rpm. And it's been pointed out that dropping boost past 6500 would be a better way to achieve it, for the reasons you stated above.
That explains it.. I forgot that was the problem. For some reason I thought you can 2d map control the boost (against rpm).
Cant wait for you to get the new Haltech SA and unleash the ponies..
That explains it.. I forgot that was the problem. For some reason I thought you can 2d map control the boost (against rpm).
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There is also a small turbo efficiency gain at higher boost by running the turbo well inside its compressor map which does offset the extra heat of compression somewhat. I did do the exercise to try calculate the difference and it still works out better to run at lower boost though.
The efficiency might be higher at higher boost but the heat and total energy will never be better. Compression requires more energy than simply moving air (more EGP) and also results in higer intake temp, as efficiency will have a secondary effect on how much the air is heated dooring compression, above the adiabatic heating from the compression it self (meaning T/P~Constant -> higher pressure requires higher temp), the efficiency gives additional heat in to the system above this compression part.
Its sad that the turbo compressor maps don't provide power absorption charts, but that would immediately clearly show that for same MAF, less boost results in less heat. but a superchargers have them and its not much different on the centrifugal compressors either (turbo or super driven)
Also another misconception is that the turbo cant blow a small boost (unrestricted) on very large MAF.. (right side line of the graph)
But that is not true.. the map is defining P1 in intake part of turbo, and P2 in exhaust part of compressor housing of the turbo.. since the Area of the exhaust is smaller than intake, compression has to happen between two measured point for high flows where the flow becomes limited.. but if we would expand the piping to the same diameter as the intake of the turbo, the pressure would drop almost to the P1 (not all the way due to heat energy absorbed from the little compression that happened in the turbo. yes it will be inefficient, but very little heat is absorbed.
Lower drive power will result in lower EGP which will result in lower IMAP for same MAF (as a result of more space in the combustion chamber, as there is less left over gases resulting in lower boost to squeeze in same amount of fresh air mass) and since it lower boost, it will be at lower temp, making it denser requiring even lower boost for same MAF but higher power output since less is wasted on driving the turbo..
Did some more wiring for safety measures on the w/m system. Also did a wiring diagram so I can remember what I did down the track. However .... Looking at that diagram makes my eyes glaze over and gives me a headache! Whether any of it actually will be effective in the long run remains to be seen, I kinda miss the simplicity of just dumping some ethanol into the tank to be honest.
Anyway , this is what I now have:
Two stage water/methanol injection .... with both nozzles post bend in UIM. Total capacity adjustable from 320 to 520cc/min.
First stage activated by boost sensor set at around 2psi and ramping up flow as boost increases.
Second stage activated by RPM (set to around 5250)
LED light comes on when line to 1st stage nozzle is pressurised.
LED light comes on when line to 2nd stage nozzle is pressurised.
Boost cut is activated if 2nd stage isn't pressurised and boost is above a preset level.
Boost cut activated if afr or boost goes out of presets.
Boost cut activated at set rpm (around 7500 )
Warning LED comes on if fluid level in W/M reservoir is low.
The system is operating really well so far.... no hesitations under part throttle etc , no detectable power loss , good adjustability.
Downside of current boost cut regime is that the inherent boost creep within the system cannot be controlled without further modifications to manifold/wastegate.
I highly doubt that any part of air volume stays unmixed with other parts of it .. by the time its time to combust, the air/fuel mixture is very homogenous. The air is VERY turbulent in the combustion chamber especially while on boost.
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Just saw this post . I think what they are demonstrating here is a single large injector in one of two ports vs one injector in each of two ports ...on an RX8. Not entirely sure though.
That is the implication I understand as well.
however, the comparison is bad if the injector is not the same as it introduces further variables (fuel droplet size as 1st one that comes to mind)
more power/ same fuel assumes higher burning efficiency (also leading to lower emissions) which is contrary to Mazda switching from 2+4 to 2+2 arrangement of fuel injectors.
08-19-2024, 06:16 AM
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