[help needed] More table needed

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yyj876790646
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More table needed

Post by yyj876790646 » Tue Jan 01, 2019 2:19 am

I want to use rusefi board on a formula student engine,which is CBR600RRF5.It's high rpm to 17000 make me start to think whether 16*16 table is enough for this engine.I've alse attched a picture of motec base map of this engine.Hope my question can be solved.Thanks in advance!
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CBR600-Motec-M84-BaseMap
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russian
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Re: More table needed

Post by russian » Tue Jan 01, 2019 2:23 am

High rpm does not direcly mean larger table is needed. A reminder that both rpm and load axises are configurable and keys do not have to be linear, you probably only care for specific regions. Also interpolation helps.

If you are 100% sure you absolutely need more cells you can recompile the firmware - this should be relatively doable, but this road would make your project and firmware custom thus harder for people to help.

Any pics of your formula setup? A year ago we have visited a formula honda 600 car here in New York but it never got anywhere
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yyj876790646
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Re: More table needed

Post by yyj876790646 » Tue Jan 01, 2019 2:45 am

russian wrote:
Tue Jan 01, 2019 2:23 am
High rpm does not direcly mean larger table is needed. A reminder that both rpm and load axises are configurable and keys do not have to be linear, you probably only care for specific regions. Also interpolation helps.

If you are 100% sure you absolutely need more cells you can recompile the firmware - this should be relatively doable, but this road would make your project and firmware custom thus harder for people to help.

Any pics of your formula setup? A year ago we have visited a formula honda 600 car here in New York but it never got anywhere
I haven't got to do the setup because I haven't decide to use which standalone ECU.The picture is the screnshot of motec project file I got from other Chinese college.You can download a Motec M84 ECU manager v.11 to open the file.By the way,if I want more table,how can I modify firmware to do it?
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russian
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Re: More table needed

Post by russian » Tue Jan 01, 2019 2:53 am

To change dimensions you start at https://github.com/rusefi/rusefi/blob/m ... config.txt and invoke relevant code generators, after which you recompile.

As I said, i really doubt you need this - but you can if you want to :)
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yyj876790646
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Re: More table needed

Post by yyj876790646 » Tue Jan 01, 2019 2:59 am

russian wrote:
Tue Jan 01, 2019 2:53 am
To change dimensions you start at https://github.com/rusefi/rusefi/blob/m ... config.txt and invoke relevant code generators, after which you recompile.

As I said, i really doubt you need this - but you can if you want to :)
Thanks a lot,maybe I can't do that because I don't have coding experience. :oops:

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Re: More table needed

Post by mk e » Tue Jan 01, 2019 6:34 pm

yyj876790646 wrote:
Tue Jan 01, 2019 2:19 am
I want to use rusefi board on a formula student engine,which is CBR600RRF5.It's high rpm to 17000 make me start to think whether 16*16 table is enough for this engine.I've alse attched a picture of motec base map of this engine.Hope my question can be solved.Thanks in advance!
The rule is that you need enough rpm points to make a good approximation of the torque curve shape. 16 is plenty on most stock automotive engines which have smooth to torque curves but not nearly enough on a radicle race engine with a torque curve with 2 or 3 inflection points in it.....but most racers ignore mistuning in the bottom 1/2 or ever bottom 2/3 of the rpm range and focus on making the top part perfect and can live with 16 points as a result but it requires a more aware driver.....which is probably not a typical FSAE driver who will probably struggle to keep it in the right gear and deal with any stumbles. Radicle engine on the street applications where you can't ignore the lowered rpm section that often need 32 rpm points, that's what I use on my street car and what I used on the FSAE car I did years ago.

On the load/TPS/MAP/MAP axis I've never seen a setup that needed more than 16 points.

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Re: More table needed

Post by mobyfab » Tue Jan 08, 2019 8:29 pm

Stock and HRC ECUs use 7x16 tables, I doubt you'd need more than the current ones.

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Re: More table needed

Post by mk e » Wed Jan 09, 2019 12:34 am

mobyfab wrote:
Tue Jan 08, 2019 8:29 pm
Stock and HRC ECUs use 7x16 tables, I doubt you'd need more than the current ones.
MAF setups I assume?

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Re: More table needed

Post by mobyfab » Wed Jan 09, 2019 8:32 pm

mk e wrote:
Wed Jan 09, 2019 12:34 am
mobyfab wrote:
Tue Jan 08, 2019 8:29 pm
Stock and HRC ECUs use 7x16 tables, I doubt you'd need more than the current ones.
MAF setups I assume?
TPS/MAP hybrid

mk e
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Re: More table needed

Post by mk e » Thu Jan 10, 2019 12:06 am

mobyfab wrote:
Wed Jan 09, 2019 8:32 pm
mk e wrote:
Wed Jan 09, 2019 12:34 am
mobyfab wrote:
Tue Jan 08, 2019 8:29 pm
Stock and HRC ECUs use 7x16 tables, I doubt you'd need more than the current ones.
MAF setups I assume?
TPS/MAP hybrid
Ahhh bikes....the modern ones have tables that small? Even spark tables? Is there a separate GPS and map table that get combined to the 7 point load axis?

I've just never had much luck with tables that small....the rpm axis in particular, I'm 11x21 at the moment on the ferrari but I set it up to accept up to 24x32 just in case. The GM injector offset table I use is 17x33 (vbatt vs pressure)and the short pulse adder table goes to 67....tables just keep getting bigger it seems.

I did see a dyno test though on youube of a mildish MAF setup where they went from a 16x16 down to a 1x1 table and didn't lose hp......it seemed a bit like a setup though so who knows, I know I've never had much luck on that path.

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Re: More table needed

Post by mck1117 » Wed Jan 23, 2019 2:37 am

It's also probably not completely unreasonable to up the VE table to 24x24, I certainly wouldn't complain about more resolution near idle. Only 1280 bytes of additional ram usage, and if we switch to 24x24xuint16 for the VE table, it uses only 128 bytes more.

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