-
Read the WELCOME ALL BMWFANATICS post.
Jezebel's Alpha N Supercharger tune
- Thread starter Burgy
- Start date
Philip Foglar
///Member
Coming along nicely!! :thumbs:
Reminds me of this! :rollsmile:
[video=youtube]
It's just wrong!
herr bmw said:
Reminds me of this! :rollsmile:
[video=youtube]
It's just wrong!
Any updates gents?!
Crash_Nemesis
///Member
So... I'll update here.
I have AEM boost and AFR gauges in the car, sitting inside Mickey Mouse pods atop the steering. HPF use them in all their turbo cars. This was in the car since I bought her from MATTQ.
After the charger installation and software was loaded, we did some AFR readings to get the correct air fuel ratio tune done, but kept noticing that the boost gauge was not registering any boost above 0psi. At idle, it sits at -20 or so, which is vacuum and what it should be sitting at. As soon as we start driving, it starts moving up to -10, then -8, -6, -4, -2 and just stops at 0psi around 4000rpm.
We thought maybe the boost gauge was kaput. We should be seeing 4-5psi.
We swapped out the gauge and sensor. Same thing. Nothing above 0psi.
Eventually drove the car hard last week Wednesday and at 7800rpm, the boost gauge blipped over to 1psi.
I was confused as hell... Then i started doing some reading and realized, we lose 4psi up here at the reef. I know that superchargers are fixed gear ratio and boost levels are controlled via pulley size, but we didn't really think the less dense air up here would affect it as much. Maybe 1 psi drop... no, 5600feet = 3-4psi drop.
The pulley I have is a 4psi wheel.
Sea Level Atmospheric pressure is 14.7
Johannesburg is 11.5
+4 psi = 15.5 which is 0.8psi more than the coast.
I laughed so damn hard. All this hard work, and the car is basically running as if it were back at the coast, plus 0.8psi.
Ha ha ha... she still pulls great tho. But man, what a fail. So... smaller pulley size needs to be fitted to the car. I need to go look at all my calculations and subtract 4psi from all of them, then choose a pulley size from that. We are currently running a 3.35" pulley. I have a 2.62" pulley but that might be too small. Will update after my brain does the math.
Interesting week.
PS. That being said, here is a little teaser video to show all the work that has gone into this car since December of last year.
Enjoy.
[align=center][video=youtube]
I have AEM boost and AFR gauges in the car, sitting inside Mickey Mouse pods atop the steering. HPF use them in all their turbo cars. This was in the car since I bought her from MATTQ.
Above pic is NOT my car, but looks pretty much identical"
After the charger installation and software was loaded, we did some AFR readings to get the correct air fuel ratio tune done, but kept noticing that the boost gauge was not registering any boost above 0psi. At idle, it sits at -20 or so, which is vacuum and what it should be sitting at. As soon as we start driving, it starts moving up to -10, then -8, -6, -4, -2 and just stops at 0psi around 4000rpm.
We thought maybe the boost gauge was kaput. We should be seeing 4-5psi.
We swapped out the gauge and sensor. Same thing. Nothing above 0psi.
Eventually drove the car hard last week Wednesday and at 7800rpm, the boost gauge blipped over to 1psi.
I was confused as hell... Then i started doing some reading and realized, we lose 4psi up here at the reef. I know that superchargers are fixed gear ratio and boost levels are controlled via pulley size, but we didn't really think the less dense air up here would affect it as much. Maybe 1 psi drop... no, 5600feet = 3-4psi drop.
The pulley I have is a 4psi wheel.
Sea Level Atmospheric pressure is 14.7
Johannesburg is 11.5
+4 psi = 15.5 which is 0.8psi more than the coast.
I laughed so damn hard. All this hard work, and the car is basically running as if it were back at the coast, plus 0.8psi.
Ha ha ha... she still pulls great tho. But man, what a fail. So... smaller pulley size needs to be fitted to the car. I need to go look at all my calculations and subtract 4psi from all of them, then choose a pulley size from that. We are currently running a 3.35" pulley. I have a 2.62" pulley but that might be too small. Will update after my brain does the math.
Interesting week.
PS. That being said, here is a little teaser video to show all the work that has gone into this car since December of last year.
Enjoy.
[align=center][video=youtube]
question... if with the boost it is the same as NA at the coast why could the stock injectors not keep up and provide enough fueling?
Crash_Nemesis
///Member
Those calculations were correct, but they were for sea level. Never took into account the 4psi we lose up here. Wasn't aware that we lost 4psi until now. Fact is, supercharged cars lose the exact same amount of power an NA car loses by coming up to the highveld.
Tune file wasn't for stock injectors, it was for 440cc and 4psi. But we ran the stock injectors in the interim
moranor@axis said:
Tune file wasn't for stock injectors, it was for 440cc and 4psi. But we ran the stock injectors in the interim
Rommies
Active member
great video Chris! I love the music! Please can you take me for a drive one day if your car is 100% sorted? :=):
Look all I know is...N/A cars suffer the most here at the Highveld.
Believe it or not....turbo cars also lose plus/minus 3-5% of their power here at the Highveld. it may not sound much....but take for example a 300kw car....that's about 15kw. The simple reason is because the amount of oxygen per cubic whatever is less (if I can call it like that) - We are 1 753 metres (6 000 feet) above sea level. its literally like we are living on a mountain far up in the sky...where oxygen is little compared down on the ground.
I always explain it like this...I have a empty 5L bottle and you also have a 5L empty bottle but you are at the coast. If you can test the amount of oxygen available in your 5L bottle vs mine (here at the Highveld) you will see that yours have way more oxygen molecules.
Now im not tooo clued up on superchargers/supercharged cars....but they def. lose some power here at the Highveld. (every car gets affected)
http://www.cosportbikeclub.org/forums/archive/index.php/t-51292.html
Look all I know is...N/A cars suffer the most here at the Highveld.
Believe it or not....turbo cars also lose plus/minus 3-5% of their power here at the Highveld. it may not sound much....but take for example a 300kw car....that's about 15kw. The simple reason is because the amount of oxygen per cubic whatever is less (if I can call it like that) - We are 1 753 metres (6 000 feet) above sea level. its literally like we are living on a mountain far up in the sky...where oxygen is little compared down on the ground.
I always explain it like this...I have a empty 5L bottle and you also have a 5L empty bottle but you are at the coast. If you can test the amount of oxygen available in your 5L bottle vs mine (here at the Highveld) you will see that yours have way more oxygen molecules.
Now im not tooo clued up on superchargers/supercharged cars....but they def. lose some power here at the Highveld. (every car gets affected)
http://www.cosportbikeclub.org/forums/archive/index.php/t-51292.html
Crash_Nemesis
///Member
Thanks Rommies.
Fact is, Superchargers lose the exact same percentage of power than NA cars when at altitude. Turbo's have a waste gate that allows the turbo to spin faster and produce more boost to compensate for the lesser air density. Superchargers cannot do this as they are fixed gear and produce only as much boost as the pulley wheel fitted to them allows for.
People think that sea level = 0 psi. That is incorrect.
Sea level = 14.7 atmospheric psi. Anything above that we call boost. So, 15.7 atmospheric psi is 1psi of boost.
This supercharger pulley was meant to produce 18.7 atmospheric psi, thus 4psi of boost.
But we are 6000feet above sea level, that is 11.5 atmospheric psi. -3.2psi loss.
Add the supercharger and I get 15.5 atmospheric psi, which is 0.8psi of boost.
LOL. Was pretty funny after realizing this. Man, I feel like a dumbass. You would think VF or Active Auto ask you, what altitude are you at? before sending you a 4 psi pulley that is meant to only produce 4 psi at sea level.
Anyway, Peter and I have discovered that from countless hours researching and speaking to guys at Vortech etc, it can be said that Supercharged cars are allowed to use the same SAE Dyno corrected values as an NA car when at altitude. Turbos cannot.
Let me rephrase, any supercharged car except a German built one. Ha ha. They love their efficiency. The Audi S4 uses a Roots supercharger, not centrifugal like mine. The supercharger may not be losing much of anything as the bypass system Audi developed should be able to compensate for the lower atmospheric pressure by holding the valve closed longer, thus keeping absolute manifold pressure pretty close to what it would be at sea level. Not sure how much it ill compensate though. But the losses will be less.
Fact is, Superchargers lose the exact same percentage of power than NA cars when at altitude. Turbo's have a waste gate that allows the turbo to spin faster and produce more boost to compensate for the lesser air density. Superchargers cannot do this as they are fixed gear and produce only as much boost as the pulley wheel fitted to them allows for.
People think that sea level = 0 psi. That is incorrect.
Sea level = 14.7 atmospheric psi. Anything above that we call boost. So, 15.7 atmospheric psi is 1psi of boost.
This supercharger pulley was meant to produce 18.7 atmospheric psi, thus 4psi of boost.
But we are 6000feet above sea level, that is 11.5 atmospheric psi. -3.2psi loss.
Add the supercharger and I get 15.5 atmospheric psi, which is 0.8psi of boost.
LOL. Was pretty funny after realizing this. Man, I feel like a dumbass. You would think VF or Active Auto ask you, what altitude are you at? before sending you a 4 psi pulley that is meant to only produce 4 psi at sea level.
Anyway, Peter and I have discovered that from countless hours researching and speaking to guys at Vortech etc, it can be said that Supercharged cars are allowed to use the same SAE Dyno corrected values as an NA car when at altitude. Turbos cannot.
Magneto said:
Let me rephrase, any supercharged car except a German built one. Ha ha. They love their efficiency. The Audi S4 uses a Roots supercharger, not centrifugal like mine. The supercharger may not be losing much of anything as the bypass system Audi developed should be able to compensate for the lower atmospheric pressure by holding the valve closed longer, thus keeping absolute manifold pressure pretty close to what it would be at sea level. Not sure how much it ill compensate though. But the losses will be less.
Similar threads
