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Home > MS Trials & Testing > Megasquirt Port Injection Trial | |||||||
152 Posts Member #: 1074 Advanced Member Northamptonshire |
26th Jan, 2008 at 07:39:55pm
I wonder if you had two injectors per port, one firing upstream, one downstream and calculated the transport delay (hence position relative to the valve) that it could still work with the current code. |
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152 Posts Member #: 1074 Advanced Member Northamptonshire |
26th Jan, 2008 at 07:40:08pm
I wonder if you had two injectors per port, one firing upstream, one downstream and calculated the transport delay (hence position relative to the valve) that it could still work with the current code.
Edited by matnrach on 26th Jan, 2008. |
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![]() 8604 Posts Member #: 573 Formerly Axel Podland |
28th Jan, 2008 at 10:56:59am
On 26th Jan, 2008 matnrach said:
I wonder if you had two injectors per port, one firing upstream, one downstream and calculated the transport delay (hence position relative to the valve) that it could still work with the current code. The problem is that the ideal point of injection, in terms of cranks degrees, varies with the engine volumetric efficiency. So you would need some variable length runners. I'm going to attempt to calculate the advance/retard curve for the siamesed code so that we have a reasonable starting point. If you start with known parameters of port area and length, engine airflow based on rpm and cylinder capacity, you just need to estimate the engine VE to calculate the advance required to get the fuel in the outer cylinder just as the inlet valve is opening. I just need a torque curve for my engine, then I can estimate the VE and go from there. Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
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![]() 6744 Posts Member #: 828 Post Whore uranus |
28th Jan, 2008 at 01:09:48pm
ve would effect the pulse width , rpm and flow speed the point of inj .in my rarely expressed and ever so humble opinion . Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM |
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![]() 8604 Posts Member #: 573 Formerly Axel Podland |
28th Jan, 2008 at 01:36:52pm
I have based my calcs on Marcel's method as detailed here:
Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
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![]() 6744 Posts Member #: 828 Post Whore uranus |
28th Jan, 2008 at 02:17:06pm
yep the point is paul , the ve doesnt reflect the mass of air that is going into the cyl , it reflects the mass of air that is going into the cylinder,,,and being trapped there upon the valve shutting ... ,eg
Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM |
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![]() 8604 Posts Member #: 573 Formerly Axel Podland |
28th Jan, 2008 at 02:38:08pm
This is a very complicated subject if you start to consider what is happening in too much detail. My intention is to try to get a base timing curve that will get the car working and then Sturgeo will fine tune it whist I'm driving it with my eyes fix firmly on the road ahead Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
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![]() 6744 Posts Member #: 828 Post Whore uranus |
28th Jan, 2008 at 03:47:15pm
yep thats what i would do too paul , looking at the sheets , i may be drivelling but your not going to get the same bhp at 6k as at 5k if it flows the same amount of air ,due to the internal friction going up maybe 5 to 8 bhp .
Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM |
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520 Posts Member #: 2093 Post Whore Grenoble, France |
28th Jan, 2008 at 03:50:21pm
On 28th Jan, 2008 Paul S said:
The problem is that the ideal point of injection, in terms of cranks degrees, varies with the engine volumetric efficiency. So you would need some variable length runners. Paul, could you explain why the transport delay would depend on VE or MAP ? std 998 A+, g295, MD266, RHF4, 109hp @0.8bar/5400rpm |
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![]() 8604 Posts Member #: 573 Formerly Axel Podland |
28th Jan, 2008 at 04:08:05pm
On 28th Jan, 2008 alpa said:
Paul, could you explain why the transport delay would depend on VE or MAP ? The above spreadsheets show how the transport delay may vary with VE. I'm still thinking about the effects of MAP. I'm inclined to think that as the pressure drops under vacuum, the volume increases and the speed goes up, so less advance required. I need to sleep on it. Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
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![]() 8604 Posts Member #: 573 Formerly Axel Podland |
28th Jan, 2008 at 04:12:22pm
On 28th Jan, 2008 robert said:
im just getting up to speed being laid up and nothing to do lol. Are you unwell? I'll try and keep you entertained. I'm working, but have about 3/4 more weeks crunching numbers to get this catchment model built, hence, I need this distraction. Other than test drive the car, I've only left the village about three times since Christmas! Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
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520 Posts Member #: 2093 Post Whore Grenoble, France |
28th Jan, 2008 at 04:20:27pm
On 28th Jan, 2008 Paul S said:
On 28th Jan, 2008 alpa said:
Paul, could you explain why the transport delay would depend on VE or MAP ? The above spreadsheets show how the transport delay may vary with VE. I'm still thinking about the effects of MAP. I'm inclined to think that as the pressure drops under vacuum, the volume increases and the speed goes up, so less advance required. I need to sleep on it. I'm sorry, I've read all your documents. I don't see any explanation of why. Why would the air speed change for different pressures ? Do you then make connection between MAP and VE ? std 998 A+, g295, MD266, RHF4, 109hp @0.8bar/5400rpm |
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![]() 8604 Posts Member #: 573 Formerly Axel Podland |
30th Jan, 2008 at 09:53:15am
On 28th Jan, 2008 Paul S said:
I'm still thinking about the effects of MAP. I'm inclined to think that as the pressure drops under vacuum, the volume increases and the speed goes up, so less advance required. I need to sleep on it. After further consideration, I do not think that MAP has a significant affect on the advance. Principally because MAP affects mass flow rather than volumetric flow. It's a fact that VE affects the volumetric flow at WOT and the above calcs will be my starting point. I think that maybe, my calculation of VE at 1000rpm is rather pessimistic, because I'm sure that I do not have that much advance at present and it is still injecting too early. I'm hoping to generate an .msq file, flash in the siamesed code and give it a whirl at the weekend. As long as there is not too much snow! Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
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![]() 6744 Posts Member #: 828 Post Whore uranus |
30th Jan, 2008 at 01:09:50pm
!!!is this whole siamese code allready in existence then paul ? Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM |
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![]() 1849 Posts Member #: 672 The oversills police Oslo, Norway |
30th Jan, 2008 at 01:10:50pm
yes it is. Jean finished it and made available for testing quite a while ago. |
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![]() 8604 Posts Member #: 573 Formerly Axel Podland |
30th Jan, 2008 at 01:13:44pm
On 30th Jan, 2008 robert said:
!!!is this whole siamese code allready in existence then paul ? Do try and keep up, robert. Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
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![]() 6744 Posts Member #: 828 Post Whore uranus |
30th Jan, 2008 at 01:23:13pm
gosh ,the amount of times i ve heard that in the bedroom!
Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM |
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![]() 1849 Posts Member #: 672 The oversills police Oslo, Norway |
30th Jan, 2008 at 01:25:32pm
lol! |
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520 Posts Member #: 2093 Post Whore Grenoble, France |
31st Jan, 2008 at 11:06:17am
On 30th Jan, 2008 Paul S said:
After further consideration, I do not think that MAP has a significant affect on the advance. Principally because MAP affects mass flow rather than volumetric flow. It's a fact that VE affects the volumetric flow at WOT and the above calcs will be my starting point. Yes Paul, more precisely VE affects especially in the NOT throttled mode because the bottleneck is on the engine side, not in the intake plenum/throttle. (At low RPM the NOT throttled mode is reached far before WOT). We know when we are in throttled mode, it's when MAP is lower then the ambient pressure. In throttled mode VE affects the instant air speed, but its effect on the average speed is difficult to predict and I would not consider it. My main problem now is to find how to weight outer injection time to get the same richness as in the inner. I don't think it's just a stupid multiplier, I believe it depends on the fuel film thickness and transport delay. std 998 A+, g295, MD266, RHF4, 109hp @0.8bar/5400rpm |
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520 Posts Member #: 2093 Post Whore Grenoble, France |
1st Feb, 2008 at 09:55:56am
Yesterday I read some recent papers to check if Heywood's statements are still confirmed. It looks like they are still true, the fuel film dynamics can be described by a liquid fraction (MAP/engine temperature dependend) and evaporation time (tau, 0.5-1.5 seconds on MPI).
std 998 A+, g295, MD266, RHF4, 109hp @0.8bar/5400rpm |
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520 Posts Member #: 2093 Post Whore Grenoble, France |
1st Feb, 2008 at 09:56:07am
Yesterday I read some recent papers to check if Heywood's statements are still confirmed. It looks like they are still true, the fuel film dynamics can be described by a liquid fraction (MAP/engine temperature dependend) and evaporation time (tau, 0.5-1.5 seconds on MPI).
Edited by alpa on 1st Feb, 2008. std 998 A+, g295, MD266, RHF4, 109hp @0.8bar/5400rpm |
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![]() 8604 Posts Member #: 573 Formerly Axel Podland |
1st Feb, 2008 at 06:38:00pm
I'm not convinced that evaporation is the problem, but you probably know a lot more than me about this subject, so best of luck.
Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
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Forum Mod 10980 Posts Member #: 17 ***16*** SouthPark, Colorado |
1st Feb, 2008 at 07:05:57pm
Looking forwards to it! On 17th Nov, 2014 Tom Fenton said:
Sorry to say My Herpes are no better Ready to feel Ancient ??? This is 26 years old as of 2022 https://youtu.be/YQQokcoOzeY |
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520 Posts Member #: 2093 Post Whore Grenoble, France |
1st Feb, 2008 at 08:01:34pm
It's going to snow here in Grenoble :(
std 998 A+, g295, MD266, RHF4, 109hp @0.8bar/5400rpm |
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