Does One Need a Specific Pulley Ratio for Proper Tune Performance?

[Bartlett]

I'll set the stage with a specific scenario: if someone with a 3.10 pulley ratio runs Stage 2 ECU and TCU tunes (let's agree Stage 2 generally = 57mm pulley only, so ~2.80 ratio), should they expect any problems or weird behavior, such as clutch slippage, fuel cuts, slower performance, etc? To pose a scenario, would the ECU be sending lower torque readings and causing shifting problems?

Does anyone have any concerns, or has anyone noticed any issues with running a higher pulley ratio than a tune "officially" supports? Is there any merit to using the exact pulley ratio the tuner advertises with their pulley hardware kits?

[01northernS4]

I'll set the stage with a specific scenario: if someone with a 3.10 pulley ratio runs Stage 2 ECU and TCU tunes (let's agree Stage 2 generally = 57mm pulley only, so ~2.80 ratio), should they expect any problems or weird behavior, such as clutch slippage, fuel cuts, slower performance, etc? To pose a scenario, would the ECU be sending lower torque readings and causing shifting problems?

Does anyone have any concerns, or has anyone noticed any issues with running a higher pulley ratio than a tune "officially" supports? Is there any merit to using the exact pulley ratio the tuner advertises with their pulley hardware kits?

I've heard and read here that headroom is built into these reputable tunes so running a higher ratio can be beneficial in some cases... logging I'm told, is key when doing this to find the sweet spot and avoid these potentially "weird behaviors"...

That being said I believe some tuners absolutely advise against it... I'd personally have no trouble trying it when logging.

Perhaps someone with more experience can chime in.

Hope that helps.

[djn876]

The car will adjust fueling as it needs to since it will require more than the tune has for a base amount, but if it's reasonably close you won't have any issues. I agree logging is the only way to tell.

Going from a 2.8 to a 3.10 is a pretty big jump. The car will run fine but you really should be running a DP tune to maximize it as you might start bleeding boost.

The ECU is going to send the data it has, changing the PR isn't going to change how the ECU responds. That being said, if you start challenging the ECUs/TCUs torque limits, it will take action to keep things within bounds. At a 3.10, I don't expect that to happen unless the tune is conservative.

Why not just update to a DP tune?

Sent from my SM-G988U using Audizine Forum mobile app (http://r.tapatalk.com/byo?rid=87676)

[Bartlett]

I've heard and read here that headroom is built into these reputable tunes so running a higher ratio can be beneficial in some cases... logging I'm told, is key when doing this to find the sweet spot and avoid these potentially "weird behaviors"...

That being said I believe some tuners absolutely advise against it... I'd personally have no trouble trying it when logging.

Perhaps someone with more experience can chime in.

Hope that helps.

While logging can help diagnose the issue, I am trying to understand if there should be an issue to begin with.

I figure that a tune should be able to support higher or lower ratios, as I see many people with the same DP tune running ratios ranging from 3.15 to 3.4+.


The car will adjust fueling as it needs to since it will require more than the tune has for a base amount, but if it's reasonably close you won't have any issues. I agree logging is the only way to tell.

Going from a 2.8 to a 3.10 is a pretty big jump. The car will run fine but you really should be running a DP tune to maximize it as you might start bleeding boost.

The ECU is going to send the data it has, changing the PR isn't going to change how the ECU responds. That being said, if you start challenging the ECUs/TCUs torque limits, it will take action to keep things within bounds. At a 3.10, I don't expect that to happen unless the tune is conservative.

Why not just update to a DP tune?

Sent from my SM-G988U using Audizine Forum mobile app (http://r.tapatalk.com/byo?rid=87676)

The concern isn't bled boost. Rather, it's any fuel, transmission, or other issues.

To be frank, my tune has been having noticeable problems after shifts following a 30hp power increase after a carbon cleaning. I am having trouble accepting that the tune, which has not bled boost for me yet, is actually not able to handle the extra power. If it can't, then the tuner should have ensured that the extra boost is bled.

[Izzyz28]

While logging can help diagnose the issue, I am trying to understand if there should be an issue to begin with.

I figure that a tune should be able to support higher or lower ratios, as I see many people with the same DP tune running ratios ranging from 3.15 to 3.4+.



The concern isn't bled boost. Rather, it's any fuel, transmission, or other issues.

To be frank, my tune has been having noticeable problems after shifts following a 30hp power increase after a carbon cleaning. I am having trouble accepting that the tune, which has not bled boost for me yet, is actually not able to handle the extra power. If it can't, then the tuner should have ensured that the extra boost is bled.

What are the noticeable problems after shifts?

[RecklessactN]

If you are changing pulley size IMO you need to tune for it. Think about it, you are changing the boost pressure and to have the optimal fuel/air/spark the ECU should be calibrated for any of those changes. If you run a smaller or bigger pulley, sure it will work but you wont get optimal performance.

[doughboy17]

Not sure what tuner you went with, but did you readapt the TCU tune after the carbon cleaning? If you, indeed, did obtain a 30 hp bump after the carbon cleaning, the shifting algorithm is probably not accustomed to it. When is the last time you changed your DSG fluid? Did you have other maintenance performed when you carbon cleaned?

[blackfunk]

Can't speak for any of the other tuners, but APR's stage 2 tune is the same as their DP tune. All of the necessary maps are included in both so no need for a 'second' cash outlay.

[Mike Literous]

I ran the JHM 207mm crank pulley (3.25 pulley ratio) initially with a stage1 APR, and did notice a big jump in bottom end, and it obviously bled off the excess boost at the top end. Car was very enjoyable to drive in this state of tune. Recently upgraded to the stage 2 APR, and there is definitely more top end performance, more noticeable in 3rd gear up as I assume there are torque limiters in play as I'm still on the factory TCU tune. Will probably do a TCU tune in the future to unlock some more stage 2 goodness. JHM reported that you can even run a large crank pulley with the stock software, and it will work up to when the factory boost bleeder kicks in. Most suggest the 3.2 range is the optimum balance point where the heat is manageable with just upgrading the heat exchanger.