Something I often see in tunes

[Biggbaddwolf]

A lot of times when I am looking at tunes it will say to set the power before adjusting the tranny. Just wondered why that was? Does it really make a difference..TIA

 

[nowcontrol]

Yes, adding/removing power parts in some cases drastically alters the gear ratios so it's best practice to decide on those power parts before adjusting the gears.

If you have set the gears first, when you go back to them after next setting up the power you may notice they have been messed up by the power adjustments.

You will most usually have to re-adjust the gears every time you swap around some engine parts, but not always.

 

[ALB123]

@nowcontrol is exactly right. Not only that, but if you do not set the Power adjustments first, there are many instances where you won't even be able to match the gear ratio's that the tune suggests. So, in those cases you MUST do the Power settings first, or you won't even be able to match the Transmission settings.

 

[Vegard]

This only applies to power parts that alter the rev range:

-Engine stages
-ECU
-Exhaust
-Cat

 

[Jaywalker]

This only applies to power parts that alter the rev range:

-Engine stages
-ECU
-Exhaust
-Cat

Manifolds
Intakes
Turbos
Superchargers

Oil changes

 

[Vegard]

@Jaywalker

Why don't you try that for yourself and see if it changes anything?

 

[DolHaus]

@nowcontrol and @Vegard have it correct:-

If the engine parts fitted have any effect on the RPM limit then it will affect the numerical ranges available for the individual gears. If you attempt to set the gears before fitting certain engine parts then you may not be able to reach the desired ratios 👍

 

[Jaywalker]

I

@Jaywalker

Why don't you try that for yourself and see if it changes anything?

I have, & in many cases it does. With most Praiano tunes, if you don't get the power parts 100% the same, you won't get the ratios...

 

[Vegard]

I have, & in many cases it does.

If you could give one specific example so I can try it myself that would be nice, thank you.

 

[Jaywalker]

If you could give one specific example so I can try it myself that would be nice, thank you.

OK. Take Praiano's BMW M3 CSL '03 tune at 500PP.

His ratios are:

1st: 2,877 2nd: 2,272 3rd:1,830 4th: 1,505 5th: 1,261 6th: 1,070

Now re-set the gearbox to default, add the manifold & intake, tune power back to 500PP & try & match those ratios.

You can't. You'll only get 2nd & 3rd.

The closest you can get for the others is: 1st: 3,013 4th:1,452 5th: 1,137 6th: 0,936

That's what I meant.

 

[Vegard]

Now re-set the gearbox to default, add the manifold & intake, tune power back to 500PP & try & match those ratios.

I did exactly as you said and had no problem matching the gears to what they were before

 

[Jaywalker]

I did exactly as you said and had no problem matching the gears to what they were before

We must be doing something differently? Did you first do his 500PP tune with his added parts, then re-set the box & add the manifold & intake & then reduce power back to 500 PP? There's no way I can get the ratios...

 

[Wide Boy]

As said unless the rev range changes why would the gearing be affected?

 

[Vegard]

There's no way I can get the ratios...

I did exactly as you described. Of course, I had to flip the gearbox again but that's nothing new.

 

[Wide Boy]

Try doing this also I have done it on a couple of cars where I wanted the same gearbox but its ratio range was slightly different.

When you flip the gearbox don't move the final all the way to the right.
If it goes to 5 try somewhere in the high 4s 4.6 4.7 etc.
Try it look at first & adjust it if you cant get it.
You will get a gearbox that will have an identical or slightly smaller or wider range, within 0.002.
So first or top will be out by a couple of hundredths.