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Old 05-02-2009, 05:02 AM   #1
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Smile How do calculate Cranking and Acceleration for 360cc ?

Hi, how does this works with the cranking and acc enrichment to calculate?

i have 360cc injectors from a GTX 323 running on my Miata.
My Turbocharger is a Greddy TD04

Can anyone help me to calculate the near right settings please?
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Old 05-02-2009, 07:51 PM   #2
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From the MSPNP manual:

Injectors

MSPNP can drive a wide variety of injectors, typically when using the MegaSquirt on Miata’s users have reported better results with High Impedance injectors. We’d suggest the same until we’ve done further testing to ensure that this was a limitation or mis-configuration of a specific user’s setup and nothing else. High Impedance injectors are available for the Miata up to 550cc which will handle most of your needs.

When you change the injector size, MegaSquirt can handle most of the adjustments with just one variable, REQ_FUEL, which sets the base pulse width. MegaTune can calculate this value automatically if you click the Required Fuel button on the Engine Constants page, where you just need to enter your engine size and injector size, as well as 12.7 for the air/fuel ratio. Using that A/F ratio will reduce the amount of tuning needed when you change injectors significantly as that’s what was used for the req_fuel calculation on the base map with stock injectors. Yes we know the MegaManual advises uses 14.7 for gasoline as the stoich ratio, please note that, within reason, it doesn't matter and there was a reason we chose to use a different AFR here. If you're wanting to scale for different injectors with minimal re-tuning then use the AFR we recommend. If you are going to fully retune anyways then feel free to use 14.7 as the AFR. It won't effect your ability to tune your car properly at all. It will effectively scale your entire VE table a bit.

Here are the settings we used on the base map to come up with a REQ_FUEL of 13.4:



There are a few settings which do not adjust when you change REQ_FUEL as they are static pulsewidth (PW) settings, so you will need to adjust these by hand. The acceleration enrichment settings will probably need to be retuned for the new injectors. Also, larger injectors require shorter cranking pulse widths. If you double your injector size, you will need approximately half the cranking pulse width. As a general rule, it’s easier to fine tune the cranking pulse widths by setting them to a lower value than expected, and then increase this in 0.1-0.2 millisecond increments until the engine starts. This will make it less likely that you flood the engine.

For both the cranking PW and Accel Enrichment PW you can do much of the adjustments using math—then do the rest via fine tuning.

For example—you need to first subtract the injector opening time from your current numbers. Injector opening time by default is set to 1.0ms. So if your Cranking PW at 100degF is 4ms, subtract 1.0ms from that and you have 3ms. Now, that that 3ms and divide it by the percentage of the size difference of the new injectors compared to the old. If you had 20lb stock injectors, and you’re going to 42lb injectors, you’ll need about ½ the cranking PW minus the opening time. So in this case, ½ that 3.0ms is 1.5ms. Add that 1.0ms injector opening time back and you’ve got 2.5ms. Your old cranking PW at 100degF was 4ms, your new time at the same temp is 2.5ms. This should be pretty close to what’s needed. Do this for all cells in your cranking PW and Accel Enrichments and you’ll be close with only fine tuning remaining.

After swapping in new injectors and making these adjustments, it’s a good idea to make sure your air-fuel ratios are still where they should be. Sometimes the VE table will need a bit of fine tuning due to differences in the way injectors behave, and it’s also a math check for the changes you just made. Make sure the air-fuel ratios are good before pushing the engine hard after an injector swap.
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Old 05-02-2009, 08:21 PM   #3
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put another shrimp on the barbi!!!!!!oneone
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Old 05-02-2009, 08:40 PM   #4
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Originally Posted by hustler View Post
put another shrimp on the barbi!!!!!!oneone

He's Austrian, not Australian!
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Old 05-02-2009, 09:03 PM   #5
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He was quoting Dumb and Dumber! lol
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Old 05-02-2009, 09:10 PM   #6
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He was quoting Dumb and Dumber! lol
Well I guess that's a movie I haven't seen and don't plan to see.

Just in case it's contagious
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Old 05-02-2009, 09:14 PM   #7
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Quote:
Originally Posted by xitsam View Post
Hi, how does this works with the cranking and acc enrichment to calculate?

i have 360cc injectors from a GTX 323 running on my Miata.
My Turbocharger is a Greddy TD04

Can anyone help me to calculate the near right settings please?
Ich habe keine idea fur die megasquirt. Es ist nicht kompliziert, aber im Allgemeinen. Enrichen der Tabelle, bis das Fahrzeug gestartet wird. Hier finden Sie eine allgemeine Anleitung zu Bereicherung Werte hier. http://www.boundaryengineering.com/instructions.zip Dies ist die Adaptronic Programm, aber die Werte sind immer noch gültig.

Mein Deutsch ist leider nicht die beste ...
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Old 05-02-2009, 09:36 PM   #8
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Originally Posted by TravisR View Post
Ich habe keine idea fur die megasquirt. Es ist nicht kompliziert, aber im Allgemeinen. Enrichen der Tabelle, bis das Fahrzeug gestartet wird. Hier finden Sie eine allgemeine Anleitung zu Bereicherung Werte hier. http://www.boundaryengineering.com/instructions.zip Dies ist die Adaptronic Programm, aber die Werte sind immer noch gültig.

Mein Deutsch ist leider nicht die beste ...

Travis; I'm thoroughly impressed!
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Old 05-03-2009, 04:07 AM   #9
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He's Austrian, not Australian!
tard.
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Old 05-03-2009, 08:53 AM   #10
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tard.
long time not felt your wrath!
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Old 05-04-2009, 04:03 PM   #11
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Quote:
Originally Posted by TravisR View Post
Ich habe keine idea fur die megasquirt. Es ist nicht kompliziert, aber im Allgemeinen. Enrichen der Tabelle, bis das Fahrzeug gestartet wird. Hier finden Sie eine allgemeine Anleitung zu Bereicherung Werte hier. http://www.boundaryengineering.com/instructions.zip Dies ist die Adaptronic Programm, aber die Werte sind immer noch gültig.

Mein Deutsch ist leider nicht die beste ...
Thanks for help, i will give it a try

The only problem i have is, i dont realy understand the hole Manual from the MS, this is why i ask here

I know, when a noob ask some stubide questions, no one want help, but if a not german speaking citzen wants to read a german manual, he will also have his problems.. specialy on technical stuff.

And for the funny guy :9

NO Kangaroos in Austria :P
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Old 05-04-2009, 04:14 PM   #12
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For example—you need to first subtract the injector opening time from your current numbers. Injector opening time by default is set to 1.0ms. So if your Cranking PW at 100degF is 4ms, subtract 1.0ms from that and you have 3ms. Now, that that 3ms and divide it by the percentage of the size difference of the new injectors compared to the old. If you had 20lb stock injectors, and you’re going to 42lb injectors, you’ll need about ½ the cranking PW minus the opening time. So in this case, ½ that 3.0ms is 1.5ms. Add that 1.0ms injector opening time back and you’ve got 2.5ms. Your old cranking PW at 100degF was 4ms, your new time at the same temp is 2.5ms. This should be pretty close to what’s needed. Do this for all cells in your cranking PW and Accel Enrichments and you’ll be close with only fine tuning remaining.


Now i got the point, i think i understand now what i have to calc.
And sorry for my Noob question.....

Btw.. I saw the Movie Dump and Dumperer
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