Got myself an X51 air box, GT3 throttle body, plenum, before & after dynos
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I'm not running any tune (yet) but probably will go with Softronics...
How do you know your car is running lean?
I don't have a problem with throttle response or low torque at below 3000rpms...
yes, that's a NHP plenum
How do you know your car is running lean?
I don't have a problem with throttle response or low torque at below 3000rpms...
yes, that's a NHP plenum
Registered User
Joined: Dec 2007
Posts: 1,749
From: Miami
Rep Power: 125
I'm not running any tune (yet) but probably will go with Softronics...
How do you know your car is running lean?
I don't have a problem with throttle response or low torque at below 3000rpms...
yes, that's a NHP plenum
How do you know your car is running lean?
I don't have a problem with throttle response or low torque at below 3000rpms...
yes, that's a NHP plenum
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Joined: Feb 2011
Posts: 127
Rep Power: 71
Hi there
Well went to the dyno today in short with 82mm, tb, plenum and X51 Airbox car made 375BHP, 4BHP more peak than last time, but had lost torque and power sub 3000rpm.
So put stock tb and plenum back on and throttle response improved and the low-down torque/power came back but car made 370BHP peak.
However both runs had a major issue, car was lean, LEAN LEAN!!
This shop does tuning for several makes, but not Porsche unfortunately, however they have got down to the bottom of the cause:
The tube where the maf inserts on the stock and X51 Airbox are different in diameter. The X51 Airbox has a larger diameter tube and the stock or the softronic map can't account for this. Due to the larger diameter the X51 Airbox flows a lot more air pass the maf without it realising this. Because maf calculates airflow based on speed of airflow, problem is with larger diameter tube you chase Venturi effect and as such far more air flows across the maf. As the stock maps are based on air speed and set diameter of the stock Airbox when you increase this diameter the air speed slows down but your getting more air. As such on stock map or even softronic the car air fuel ratio goes out, very badly.
As such anyone who has upgraded their car with X51 Airbox and are running the stock remap or softronic, YOUR CAR IS RUNNING LEAN!!
The only way to fix this will be to either get the X51 map from Porsche or get a custom live map done. I shall speak with Scott at softronic to see if he can help.
The dyno shop feel that with the right map which adds fuel I'd also be able to run 82mm tb and have good throttle response as with stock but also make more power everywhere and no doubt get over 380ish peak.
Well went to the dyno today in short with 82mm, tb, plenum and X51 Airbox car made 375BHP, 4BHP more peak than last time, but had lost torque and power sub 3000rpm.
So put stock tb and plenum back on and throttle response improved and the low-down torque/power came back but car made 370BHP peak.
However both runs had a major issue, car was lean, LEAN LEAN!!
This shop does tuning for several makes, but not Porsche unfortunately, however they have got down to the bottom of the cause:
The tube where the maf inserts on the stock and X51 Airbox are different in diameter. The X51 Airbox has a larger diameter tube and the stock or the softronic map can't account for this. Due to the larger diameter the X51 Airbox flows a lot more air pass the maf without it realising this. Because maf calculates airflow based on speed of airflow, problem is with larger diameter tube you chase Venturi effect and as such far more air flows across the maf. As the stock maps are based on air speed and set diameter of the stock Airbox when you increase this diameter the air speed slows down but your getting more air. As such on stock map or even softronic the car air fuel ratio goes out, very badly.
As such anyone who has upgraded their car with X51 Airbox and are running the stock remap or softronic, YOUR CAR IS RUNNING LEAN!!
The only way to fix this will be to either get the X51 map from Porsche or get a custom live map done. I shall speak with Scott at softronic to see if he can help.
The dyno shop feel that with the right map which adds fuel I'd also be able to run 82mm tb and have good throttle response as with stock but also make more power everywhere and no doubt get over 380ish peak.
Ken
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Throttle response improved sub 3000rpm with stock tb, but this is maybe tied to the fact the 82mm throttle lost torque and power below that point.
With more fuel and right mapping, it should have more power everywhere, but softronic won't work unless Scott can investigate this and come up with a fix for the softronic tune.
Last edited by Gibbo205; May 3, 2013 at 01:36 PM.
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1. We fitted stock plenum and throttle body, still lean
2. Euro cup plenum uses same t design as stock
3. Checked for air / vacuum leaks, none!
Problem is the X51 airbox, our cars map fuel the car based on maf air speed, but the X51 has a larger diameter tube where the maf inserts. This mean for same air speed more air is actually flowing, hence LEAN!
Only way to fix is with a custom remap or the Porsche X51 map.
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On stock throttle body with X51 intake it runs superb and still sounds ace.
But knowing my car is running lean I want to sort it, lean running could seriously reduce the engines life.
The guys who ran my car know there stuff and what they said makes perfect sense, our cars can't fuel for the additional air volume as the maf is not seeing any additional air speed, so it's un-aware of the extra air volume due to larger diameter tube where the maf is inserted. You guys should get your car on the dyno and get the AFR checked, because lean is not good.
Last edited by Gibbo205; May 3, 2013 at 04:12 PM.
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I don't disagree with you. I have the Softronic tune and the told me it would compensate for all the mods. I'd love to hear how they respond to your findings. I appreciate all of your research on this!
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.
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The 997.1 3.6 intake's MAF tube internal diameter is ~86mm.
So, the X51's tube has 12% more area as compared to the 3.6 (5800 sq.mm vs 6500 sq.mm).
.
So, the X51's tube has 12% more area as compared to the 3.6 (5800 sq.mm vs 6500 sq.mm).
.
Last edited by alpine-al; May 4, 2013 at 08:21 AM.
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Thanks alpine-al, a big difference in area then - and kudos to Gibbo.
I just took my (X51) airbox out and measured it more accurately in proper daylight, turns out it's nearer 90mm than 91mm - my apologies.
So let's say the nominal MAF tube i.d.s are -
X51 - 90mm
3.6 - 86mm
3.8S-anyone?
Is there any kind of 'grid' in the MAF tube of the 3.6 or 3.8 airbox that might reduce its effective area (there's none in the X51 box)?
I just took my (X51) airbox out and measured it more accurately in proper daylight, turns out it's nearer 90mm than 91mm - my apologies.
So let's say the nominal MAF tube i.d.s are -
X51 - 90mm
3.6 - 86mm
3.8S-anyone?
Is there any kind of 'grid' in the MAF tube of the 3.6 or 3.8 airbox that might reduce its effective area (there's none in the X51 box)?