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Old 07-17-2012, 11:41 PM   #21
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From my VE math. Based on wikipedia a na8 made peak power at 6000 stock of 127 crank hp. From my math that it would mean we needed to hit a peak of 97% VE to make 127 crank hp at 6000 rpm. If we made that at 6500 it would only require 90% VE. A different and more accurate (at least I think so) calculator puts it at like 94% VE. That makes a lot more sense. http://hpwizard.com/engine-horsepower-calculator.html
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Old 07-18-2012, 12:45 AM   #22
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And in order to use those formulas you'll have to enter BSFC and air factor - right? How did you measure those?
Small variations will cause big variations in hp. Going with basic assumed values that have error margins of +/- 20% or so won't get us anywhere.
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Old 07-18-2012, 12:48 AM   #23
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And in order to use those formulas you'll have to enter BSFC and air factor - right? How did you measure those?
Small variations will cause big variations in hp. Going with basic assumed values that have error margins of +/- 20% or so won't get us anywhere.
Well do you want to claim that our cars have high VE's or a very well designed combustion chamber? We know the spark table is very conservative, and that the fueling stays closed loop until 4k rpm no matter the load. I didnt feel like monkeying with the other values at the moment without better data.
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Old 07-18-2012, 09:34 AM   #24
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I don't want to claim anything about Miata engines. That's kind of the point. We can't tell the VE without more data than appears readily available. Until such data is found or collected, there is not much point in guessing at VE.
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Old 07-18-2012, 06:33 PM   #25
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Well if you want empirical data you'll just have to wait until TS finishes my patch harness. Then at the very least we can get in the ball park since I will actually tune it correctly with all the correction factors zero'ed out to the condition which the primary tune is done in.
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Old 07-18-2012, 07:40 PM   #26
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how you gonna compute VE leafy?
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Old 07-18-2012, 10:12 PM   #27
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Well two fold. I can actually take it from my tune since I will know that I am tuning it to a ve value with no modifiers, the only wild card would be the fuel injector flow, which will not make it swing too wildy. That method should get withing +/-4% of my engine. 2nd method is to take the maf, do the math to figure out the airflow vs hz line, its pretty basic, irrc the only calculus is already derived for you. And compare the maf airflow vs rpm to the 100% ve airflow vs rpm to get the actual VE. I'm not too familiar with the equation for this style maf, but if its similar to the math from a hot wire (aka GM style) maf then this should be about +/-3%. I wont be tuning with the maf but it will still be wired up and in the air stream for a little bit. Beyond that I cant even think of another way to even test this.
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Old 07-18-2012, 10:37 PM   #28
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Where do your +/-4% and +/-3% come from?
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Old 07-18-2012, 10:49 PM   #29
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For VE its how much I realistically think the injectors could be off of their rated values, and along with noise, sensor calibrations not being exactly manufacturer spec, and random error. For maf I'm pretty much basing that on how much I expect the equations calculations to be off from real life. And I know you will ask, 90% confidence interval.
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Old 07-19-2012, 12:04 AM   #30
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Originally Posted by Leafy View Post
Well two fold. I can actually take it from my tune since I will know that I am tuning it to a ve value with no modifiers, the only wild card would be the fuel injector flow, which will not make it swing too wildy. That method should get withing +/-4% of my engine. 2nd method is to take the maf, do the math to figure out the airflow vs hz line, its pretty basic, irrc the only calculus is already derived for you. And compare the maf airflow vs rpm to the 100% ve airflow vs rpm to get the actual VE. I'm not too familiar with the equation for this style maf, but if its similar to the math from a hot wire (aka GM style) maf then this should be about +/-3%. I wont be tuning with the maf but it will still be wired up and in the air stream for a little bit. Beyond that I cant even think of another way to even test this.
what EMS?
it would be useless to figure maf in if you are not actually using it with the EMS as you will have no idea airflow vs output.
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Old 07-19-2012, 12:11 AM   #31
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what EMS?
it would be useless to figure maf in if you are not actually using it with the EMS as you will have no idea airflow vs output.
Tech, I'll try to put this as politely as possible:

I ignore everything you post. You show no ability to pay any attention to what people more knowledgeable than yourself are trying to tell you and you've demonstrated your ignorance in many ways.

If you are the "idiot" you've called yourself: try listening/reading for a while.
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Old 07-19-2012, 12:15 AM   #32
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Quote:
Originally Posted by Techsalvager View Post
what EMS?
it would be useless to figure maf in if you are not actually using it with the EMS as you will have no idea airflow vs output.
If he has a calibration curve, which is what he was talking about with the GM hot-wire equation stuff, it doesn't matter what EMS he uses. He could just leave the MAF in the air stream, hook up the proper +5 and ground and just datalog a voltage to get the airflow measurement. This is all assuming that his calibration equation relating airflow vs voltage is accurate. Regardless the point is that it doesn't matter what EMS he is using. He could datalog a voltmeter with the stock ECU and it would work fine.

Edit: ^^ ouch, burned by a noob with 2 posts.
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Old 07-19-2012, 12:21 AM   #33
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Originally Posted by baron340 View Post
If he has a calibration curve, which is what he was talking about with the GM hot-wire equation stuff, it doesn't matter what EMS he uses. He could just leave the MAF in the air stream, hook up the proper +5 and ground and just datalog a voltage to get the airflow measurement. This is all assuming that his calibration equation relating airflow vs voltage is accurate. Regardless the point is that it doesn't matter what EMS he is using. He could datalog a voltmeter with the stock ECU and it would work fine.
hahaha if thats how you think it works.
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Old 07-19-2012, 12:27 AM   #34
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hahaha if thats how you think it works.
He's absolutely correct about how it works.
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Old 07-19-2012, 12:31 AM   #35
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Originally Posted by alangbaker View Post
He's absolutely correct about how it works.
I know how it works
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Old 07-19-2012, 12:32 AM   #36
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Originally Posted by Techsalvager View Post
I know how it works
Really?

Prove it.

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Old 07-19-2012, 12:45 AM   #37
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the problem is the calibration curve is unlikely to be accurate.
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Old 07-19-2012, 12:47 AM   #38
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Originally Posted by Techsalvager View Post
the problem is the calibration curve is unlikely to be accurate.
Why? Because you say so?

Explain it... ...for real this time... ...if you can.
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Old 07-19-2012, 12:48 AM   #39
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Quote:
Originally Posted by Techsalvager View Post
hahaha if thats how you think it works.


Unteachable troll refuses to be taught
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Old 07-19-2012, 12:55 AM   #40
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Originally Posted by alangbaker View Post
Why? Because you say so?

Explain it... ...for real this time... ...if you can.
because the calibration curve that one has for it was probably taken from an ecu using the maf in a stock setup. The minute you change it out of that setup and have something else going on it could be miles off the same curve.
Any bends before or after it can easily effect that curve.

Um also what ems is leafy gonna use, if its ms2 he won't be able to use a gm maf with hz output as ms2extra doesn't support it, ms3 he can
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