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Volumetric Efficiency
I have been corresponding with Harvey regarding setting up a volumetric efficiency graph for tuning the SVX. After getting into this more, I am thinking that the volumetric efficiency calculated by Harvey might not be applicable for a turbo charged or supercharged application, since there are significant pressure drops and drops in efficiency in a FI engine than an NA engine. I think that the best way to calculate VE would be to tap into the MAF and log some real data to help narrow down these values. In fact I think that these values will certainly change even after an intercooler is added, and if any exhaust modifications are made. So this is something I would need to consider as the car modified even further.
Any thoughts on how to best log data from the MAF? Thanks Chuck D.
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Chuck D. 1992 Subaru SVX LS-L - Heavily modded turbo 2002 Subaru Impreza WRX- Turboxs stg3 & Susp. Mods |
#2
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The MAF will give you air flow values but exactly how do you wish to relate these to VE as such?
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Trevor, New Zealand. As a child, on cold mornings I gladly stood in cowpats to warm my bare feet, but I detest bull$hit! Last edited by Trevor; 06-09-2006 at 09:34 PM. |
#3
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I dont see how calculating Volumetric efficency will benefit you in tuning. What you need to know is AFR and load values, and then use the knock sensor system that came with your car to adjust accordingly, chances are you will be running close to stock timing, so maybe michael will be able to help you out.
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~Phil Teal 1992 Subaru SVX Turbo - Sold in May 2011 to peace-frog. |
#4
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I am trying to ascertain what BS has again been handed out here to a member, hence my reference to finite figures. VE can only be indicative as a ratio/percentage. It is unlikely that the extent of hot air excreted, will ever come to light. The VE of the expediter is beyond question. Cheers, Trevor.
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Trevor, New Zealand. As a child, on cold mornings I gladly stood in cowpats to warm my bare feet, but I detest bull$hit! Last edited by Trevor; 06-09-2006 at 10:36 PM. |
#5
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The Question was:
What is the best way to log data from the MAF...?? Im interested to know aswell Cheers, Jake
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1992 Pearl / Black SVX removed intake silencer, k&N pannel filter, trans cooler, 94 JDM 4eat, Noltec front swaybar mounts, Motorsport D&S disks with EBC Greenstuff pads |
#6
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The wide band that SVXFiles and Mychailo both have (okay, so I've still got Mychailo's ) both have datalogger features. If you go back and check some of Mychailo's posts, you'll see he was able to measure MAF voltage vs rpm. There really shouldn't be any reason why you can't tap into any of the lines coming out of the ECU (as long as their voltage levels are sufficient).
-Bill
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Retired NASA Rocket Scientist Most famous NASA "Child" - OSIRIS-REx delivered samples from asteroid BENNU to Earth in Sept. 2023 Center Network Member #989 '92 Fully caged, 5 speed, waiting for its fully built EG33 '92 "Test Mule", 4:44 Auto, JDM 4:44 Rear Diff with Mech LSD, Tuned headers, Full one-off suspension '92(?) Laguna, 6 spd and other stuff (still at OT's place) My Locker |
#7
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V eff
Thanks for the replies. Exactly my thoughts. VE will be different for every kind of intake exhaust application. Probably best to use the MAF. I'll check what was done before.
The reason I need it is that electromotive uses volumetric efficiency as a tuning table. I did not think I would need it either, but now that I think of it, it makes sense. The electromotive software does not use an MAF, and calculates mass air flow rate by knowing the pressure, temperature, and rpm of the motor. In order to convert from rpm to mass air flow rate, volumetric efficiency will be an important part of the equation. Although the efficiency may be from the plenum where I take my air pressure reading to the cylinder instead of the entire motor. Thanks for your input Chuck D.
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Chuck D. 1992 Subaru SVX LS-L - Heavily modded turbo 2002 Subaru Impreza WRX- Turboxs stg3 & Susp. Mods |
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Quote:
phil
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~Phil Teal 1992 Subaru SVX Turbo - Sold in May 2011 to peace-frog. |
#9
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Quote:
Harvey.
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One Arm Bloke. Tell it like it is! 95 Lsi. Bordeaux Pearl, Aust. RHD.149,000Kls Subaru BBS wheels. 97 Liberty GX Auto sedan. 320,000Kls. 04 Liberty 30R Auto Premium. 92.000kls. |
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So the figures that I gave you would be the engines characteristic VE curve. Harvey.
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One Arm Bloke. Tell it like it is! 95 Lsi. Bordeaux Pearl, Aust. RHD.149,000Kls Subaru BBS wheels. 97 Liberty GX Auto sedan. 320,000Kls. 04 Liberty 30R Auto Premium. 92.000kls. |
#11
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Quote:- "I am thinking that the volumetric efficiency calculated by Harvey might not be applicable for a turbo charged or supercharged application," As I said --- It is unlikely that the extent of hot air excreted, will ever come to light. The VE of the expediter is beyond question. Trevor.
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Trevor, New Zealand. As a child, on cold mornings I gladly stood in cowpats to warm my bare feet, but I detest bull$hit! |
#12
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Therefore if you were to insert an ammeter in the signal line you should be able to secure a useful proportional measurement, which you could plot. I would guess that only milli amps will be involved. The resistance of a moving coil, or digital instrument, should not effect the signal and in fact will be compensated for.
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Trevor, New Zealand. As a child, on cold mornings I gladly stood in cowpats to warm my bare feet, but I detest bull$hit! |
#13
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Gonna give it a try.
I might give that ammeter a try. First I may do some trial and error stuff as Phast suggests. I've got a wideband, EGT, and knock sensor, so I should be able to hone in on the correct fuel to add. I'm also looking at LANs timing numbers for his stage III supercharged engine (a little tuned down), and his high boost AFRs.
Again thanks to everyone for your help. I appreciate all the help I can get.
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Chuck D. 1992 Subaru SVX LS-L - Heavily modded turbo 2002 Subaru Impreza WRX- Turboxs stg3 & Susp. Mods |
#14
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Greetings Chuck,
I was not able to give you the required info on the MAF by PM as your mail box is full. Please do not delete any VE figures you have on file. Cheers, Trevor.
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Trevor, New Zealand. As a child, on cold mornings I gladly stood in cowpats to warm my bare feet, but I detest bull$hit! |
#15
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My Box
Quote:
Sorry about that. I went a cleaned up my box. Thanks.
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Chuck D. 1992 Subaru SVX LS-L - Heavily modded turbo 2002 Subaru Impreza WRX- Turboxs stg3 & Susp. Mods |
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