VE Map rpm bin selection

[abarneshq]

Hi could someone tell me if its okay to spread out rpm from 1000-12000 and still tune succesfully or would it be better to concentrate on lower end of scale and then change things and move onto tuning higher end of scale.
Also have seen instructions somewhere on how to change rpm on gauge on tuning screen but have not been able to find again perhaps it was on earlier vertion of software. Any help would be appreciated, Thanks

[Peter Florance]

You should put bins where the torque curve of the engine changes slope (as
if you tried to aprox the shape as a series of straight lines).
Typically you have more at the bottom than at the top. I have a 3 or 4 below
2000
After the peak torque rpm value, you may only need one or two bins as most
of the time, the fuel requirements are somewhat linear)
Peter Florance
Owner - First Fives.Org - The E12 Registry
1981 Euro BMW 528i w/3.5L & Megasquirt Fuel Injection
1981 US BMW 528i "Repo Car"
http://www.firstfives.org
mailto:peter@firstfives.org
ssr# 284

[efahl]

On Mon, October 4, 2004 8:08 am, Peter Florance said:

> You should put bins where the torque curve of the engine changes slope (as
> if you tried to aprox the shape as a series of straight lines).

I drew a picture of what Peter is talking about a couple years back:

<http://www.not2fast.com/efi/spacing.shtml>

--
Eric Fahlgren http://www.not2fast.com/

[efahl]

On Mon, October 4, 2004 7:10 am, abarneshq said:

> Also have seen instructions somewhere on how to change rpm on gauge on
> tuning screen but have not been able to find again perhaps it was on
> earlier vertion of software. Any help would be appreciated, Thanks

What version of MegaTune are you using and what variant of embedded
code?

I'll assume 2.25 and basic B&G MegaSquirt-I:

Find the file "megasquirt-I.ini" in

c:/program files/MegaSquirt/MegaTuneXXX/mtCfg/megasquirt-I.ini

Double click it to open it up in notepad, then search for the
section entitled "[GaugeConfigurations]". Read through those until
you find "tachometer" and change the values to suit your specific
requirements.

Eric

--
Eric Fahlgren http://www.not2fast.com/

[Peter Florance]

Like my hippie-optometrist used to say to me:

"One word is worth 1/1000 of a picture..."

That picture helps a lot!


Peter Florance
First Fives.Org - The E12 Registry
1981 Euro BMW 528i w/3.5L & Megasquirt Fuel Injection
1981 US BMW 528i "Repo Car"
http://www.firstfives.org
mailto:peter@firstfives.org
ssr# 284

[abarneshq]

Thanks for replies, will look for files tonight and attempt to make some changes. Alan

[abarneshq]

Thanks for replies, will look for files tonight and attempt to make some changes.I'll assume 2.25 and basic B&G MegaSquirt-I:- Yes- Alan

[KGB]

Now while I understand that concept of setting the RPM bins to points where torque curve slope changes, how do I come up with the first set of RPM bins? I mean I can just have MT generate it but how would I refine that? Would that exercise be a dyno-equipped only exercise?

[newtyres1]

Now while I understand that concept of setting the RPM bins to points where torque curve slope changes, how do I come up with the first set of RPM bins? I mean I can just have MT generate it but how would I refine that? Would that exercise be a dyno-equipped only exercise?

You can make a guesstimate for the first set of rpm bins and tune the motor. Then if you do a WOT datalog with a wideband O2 sensor you may find peaks or dips in the AFR, if these lie on chosen rpm points then you can tune them out, but if they don't, then you may have to shuffle some bins around to get a smooth AFR across the rpm band.

Ian.

[mxmang]

You usually want one VE or Ignition value to keep the car from stalling around 500 rpm say if your idle is 800-1000rpm (perhaps lower on a v8 or v10 etc) Make sure the value doesn't conflict with your cranking value.

Then you want one at around your exact idle value for your hot idle or perhaps one just below and just above. I have an ignition map that @ 20kpa has 18 degrees at 500 rpm 6 at 850 rpm and 8 at 1000 rpm, with it at 800 rpm it would hunt around for idle, it would be easier to make the ignition map the same but low advance #'s contribute to a faster warmup. And in -40 they certainly help the car crank out that heat it needs! (4banger.)

But ya, sometimes if you have a hunting idle or something picking an rpm closest to the "pit" in your idle advance table so it wont hunt. It really sucks with an 8lb flywheel in a car with 100 ft lbs of torque around idle!
(stock was 18!)

[landybehr]

low advance #'s contribute to a faster warmup

I thought that high advance would give the mixture/burnt gases more time to transfer heat to the cylinder wall = coolant. While with low advance the burn is shifted towards the time the exhaust valve opens and heat is emitted to the exhaust to a higher degree.

But I am not sure about that and would easily change my mind ! ;)

[panel]

This question is along the lines of this post so:

If you have a turbo car that puts out 10psi/170KPA then should you make your VE tables max MAP bin at 250KPA or just slightly above like 180KPA?

[FiatFreak]

This question is along the lines of this post so:

If you have a turbo car that puts out 10psi/170KPA then should you make your VE tables max MAP bin at 250KPA or just slightly above like 180KPA?

On my turbo car I placed the max MAP bin about 20 kPa higher than my highest expected boost level. I can't think of any reason to go much higher.

Patrick

[panel]

Thanks

[LouieLouie]

My situation is a little different on where to place the bins: I'm tuning a turbo Subaru EJ25 for an airplane application. I'm sitting at 300 ft elevation, approx. 100 ~ 101kPa and we're figuring 10 ~ 12lbs of boost to get to 200~225 hp and staying below 8000 ft.

What is the practical range of MAP values? Do we really need to account for values below 75kPa (absolute air pressure @ 8k ft) which we would only experience on 'final' approach.?