Engine Management stand alones for the 996
#1
09-27-2009, 03:59 PM
Join Date: Aug 2009
Location: De Pere, Wisconsin
Posts: 119
Rep Power: 20 
Engine Management stand alones for the 996
Is there any STAND ALONE engine management system(i.e. aem ems) made for the 996 c2? I have a supercharger on mine and a very very BASIC ecu upgrade that VF gives you with the supercharger. These engines got to be able to handle more than a lowsy 6psi of boost, I was thinking of throwing 10 at it so I would like a stand alone to alter that. So I'll be looking to find a smaller pulley for the car as well...
I feel theres a LOT of power to be made up with this car and if I could find something to alter the map on this car I think it would be awesome. So far it put down 380rwhp but I know theres quite a bit left in it if I can find something to tune this thing with.
Any suggestions???
I feel theres a LOT of power to be made up with this car and if I could find something to alter the map on this car I think it would be awesome. So far it put down 380rwhp but I know theres quite a bit left in it if I can find something to tune this thing with.
Any suggestions???
#2
09-27-2009, 04:30 PM
You can adapt any stand alone ECU, just need to figure out the wiring. This guys have a "kit" for it, http://www.clewett.com/products/produx.htm . I take by our sig that you have a 99 so you already have a mechanical throttle.
#3
09-27-2009, 04:48 PM
Join Date: Aug 2009
Location: De Pere, Wisconsin
Posts: 119
Rep Power: 20 You can adapt any stand alone ECU, just need to figure out the wiring. This guys have a "kit" for it, http://www.clewett.com/products/produx.htm . I take by our sig that you have a 99 so you already have a mechanical throttle.
Is there a cheaper PIGGY BACK system anybody uses that you can alter the tune on the factory computer?(i.e. greddy emanage)
#4
09-27-2009, 05:47 PM
Yes but I don't really know what is involved with a 996. I don't know if the stock DME control any other items beside the engine. Something that might be important to find out before jumping in. The only reason I know of it is because I was looking for something similar for a 993.
Another option is to use a MAP ecu. It is kind of a piggy back ECU but programmable. Again, not sure if it works with the 996s. Reason I say this is because I know there are cars out there like RX-8s that have complex CAN BUS ECUs. You put a piggy back to them and the OEM ECU will do everything possible to take over the piggy back and returning to stock settings.
Another option is to use a MAP ecu. It is kind of a piggy back ECU but programmable. Again, not sure if it works with the 996s. Reason I say this is because I know there are cars out there like RX-8s that have complex CAN BUS ECUs. You put a piggy back to them and the OEM ECU will do everything possible to take over the piggy back and returning to stock settings.
Last edited by rsalicrup; 09-27-2009 at 05:50 PM.
#5
09-27-2009, 06:10 PM
Registered User
Join Date: Aug 2004
Location: Chicagoland
Posts: 2,134
Rep Power: 122 
Your 99 996 will have less power with 10 psi than it does with your 6. Additionally, your compressor will be surging if you try to deliver 10 psi to the engine.
#6
09-28-2009, 08:45 AM
I'd look at the AEM FI/C before looking at going full standalone...
what rsalicrup is talking about is mostly cars equipped with wideband oxygen sensors from the factory... These cars for example target a lean air fuel ratio (even in boost for factory supercharged and turbocharged cars)...
If you put a piggy back controller on it, and add in some ~20% fueling to go from 14.5:1 AFR to around 12.5:1 AFR (which takes you from peak effeciency to peak horspower when you go WOT) ... then you find that the car dyno's great and makes a nice bump up in power...
Drive the car around for an hour... redyno it, and you'll find that the ECU has used it's longterm and short term fuel trims to dial out your +20% with a -20% fuel trim correction because it reads the factory wideband sensor and KNOWS that you are not sitting at the correct factory set AFR.
Now with this leaner AFR , comes also a more conservative timing... most of these cars have adaptive timing circuits with very well tuned knock sensors...
So sitting at 14.5:1 AFR, at WOT, in boost will definately mean a more coservative timing map than if you were running 12.5:1 ... this is on the same factory ECU with no timing corrections from the piggy back..
So between those 2 you lose alot of power in the tune alone. (This is the case with my C200 kompressor and i know what my next mod will be).
The trick around this is:
1- Change the target AFR for full throttle INSIDE the factory ECU ... GIAC might be able to do this, and charge a premium for it.
2- Get something called an O2 skewer... The AEM F/IC is effectively an O2 skewer and so is the simpler SplitSecond 'enricher'.
What these devices do is intercept and alter the factory wideband oxygen sensor signal going to the ECU... but they only do this at WOT... so the car can run 14.7:1 AFR as long as it likes, but when you go full throttle (or above a certain PSI) the interceptor lies to the factory ECU telling it that you are running too lean (say 16:1 AFR)... the ECU responds by adding 20% fuel till it thinks that it now sees 14.7:1 .... so now the ECU is fully happy.
But if you look at the uncorrected signal, and your ACTUAL air fuel ratio, you find it 12.5:1
so now you have TRICKED your factory ECU into WORKING WITH YOU to target a power friendly 12.5:1 AFR ... and it will continue to learn and tune TO it instead of AGAINST it as it did before..
The AEM F/IC also has the ability to alter injector duty cycle +/-50% and clamp map and MAS signals preventing the ECU from throwing 'too much pressure in manifold' check engine lights and activating limp modes.
__________________________________________________ ___
Putting all that aside.
If you're running factory cams (with overlap for a naturally aspirated car) and a factory header (for 50% less horsepower than you are making now) ... then you possibly have your supercharger fighting against 3 to 5psi of exhaust back pressure in the higher RPM ranges...
With overlap, both intake and exhaust valves are open... on naturally aspirated cars the inertia of the 'fluid' exhaust leaving the cylinder helps pull in more 'fluid' intake air during overlap... and this improves volumetric efficiency at higher rpms...
When you go supercharged and you start to overwhelm your exhaust flow capacity, you can build up a good 3 to 5 psi of exhaust back pressure in the manifolds (especially if you have close coupled cat converters integrated into the manifold) and so when both intake and exhaust valves open at the same time during overlap... you have 6psi of intake pressure (your supercharger) faced by say 3psi of exhaust back pressure (your headers) and that eventually leaves you with only 6-3=3 Psi of boost.
If you're still on stock cams and headers ... I'd swap out for higher flow large bore supercharger headers first.
Then I'd get intercooled (i don't think the VF kit is intercooled)
THEN and only then will I up the boost.
That's the best upgrade route for you ...
what rsalicrup is talking about is mostly cars equipped with wideband oxygen sensors from the factory... These cars for example target a lean air fuel ratio (even in boost for factory supercharged and turbocharged cars)...
If you put a piggy back controller on it, and add in some ~20% fueling to go from 14.5:1 AFR to around 12.5:1 AFR (which takes you from peak effeciency to peak horspower when you go WOT) ... then you find that the car dyno's great and makes a nice bump up in power...
Drive the car around for an hour... redyno it, and you'll find that the ECU has used it's longterm and short term fuel trims to dial out your +20% with a -20% fuel trim correction because it reads the factory wideband sensor and KNOWS that you are not sitting at the correct factory set AFR.
Now with this leaner AFR , comes also a more conservative timing... most of these cars have adaptive timing circuits with very well tuned knock sensors...
So sitting at 14.5:1 AFR, at WOT, in boost will definately mean a more coservative timing map than if you were running 12.5:1 ... this is on the same factory ECU with no timing corrections from the piggy back..
So between those 2 you lose alot of power in the tune alone. (This is the case with my C200 kompressor and i know what my next mod will be).
The trick around this is:
1- Change the target AFR for full throttle INSIDE the factory ECU ... GIAC might be able to do this, and charge a premium for it.
2- Get something called an O2 skewer... The AEM F/IC is effectively an O2 skewer and so is the simpler SplitSecond 'enricher'.
What these devices do is intercept and alter the factory wideband oxygen sensor signal going to the ECU... but they only do this at WOT... so the car can run 14.7:1 AFR as long as it likes, but when you go full throttle (or above a certain PSI) the interceptor lies to the factory ECU telling it that you are running too lean (say 16:1 AFR)... the ECU responds by adding 20% fuel till it thinks that it now sees 14.7:1 .... so now the ECU is fully happy.
But if you look at the uncorrected signal, and your ACTUAL air fuel ratio, you find it 12.5:1
so now you have TRICKED your factory ECU into WORKING WITH YOU to target a power friendly 12.5:1 AFR ... and it will continue to learn and tune TO it instead of AGAINST it as it did before..
The AEM F/IC also has the ability to alter injector duty cycle +/-50% and clamp map and MAS signals preventing the ECU from throwing 'too much pressure in manifold' check engine lights and activating limp modes.
__________________________________________________ ___
Putting all that aside.
If you're running factory cams (with overlap for a naturally aspirated car) and a factory header (for 50% less horsepower than you are making now) ... then you possibly have your supercharger fighting against 3 to 5psi of exhaust back pressure in the higher RPM ranges...
With overlap, both intake and exhaust valves are open... on naturally aspirated cars the inertia of the 'fluid' exhaust leaving the cylinder helps pull in more 'fluid' intake air during overlap... and this improves volumetric efficiency at higher rpms...
When you go supercharged and you start to overwhelm your exhaust flow capacity, you can build up a good 3 to 5 psi of exhaust back pressure in the manifolds (especially if you have close coupled cat converters integrated into the manifold) and so when both intake and exhaust valves open at the same time during overlap... you have 6psi of intake pressure (your supercharger) faced by say 3psi of exhaust back pressure (your headers) and that eventually leaves you with only 6-3=3 Psi of boost.
If you're still on stock cams and headers ... I'd swap out for higher flow large bore supercharger headers first.
Then I'd get intercooled (i don't think the VF kit is intercooled)
THEN and only then will I up the boost.
That's the best upgrade route for you ...
Last edited by Adandos; 09-28-2009 at 08:50 AM.
#7
09-28-2009, 08:56 AM
Registered User
Join Date: Aug 2004
Location: Chicagoland
Posts: 2,134
Rep Power: 122 I'd look at the AEM FI/C before looking at going full standalone...
what rsalicrup is talking about is mostly cars equipped with wideband oxygen sensors from the factory... These cars for example target a lean air fuel ratio (even in boost for factory supercharged and turbocharged cars)...
If you put a piggy back controller on it, and add in some ~20% fueling to go from 14.5:1 AFR to around 12.5:1 AFR (which takes you from peak effeciency to peak horspower when you go WOT) ... then you find that the car dyno's great and makes a nice bump up in power...
Drive the car around for an hour... redyno it, and you'll find that the ECU has used it's longterm and short term fuel trims to dial out your +20% with a -20% fuel trim correction because it reads the factory wideband sensor and KNOWS that you are not sitting at the correct factory set AFR.
Now with this leaner AFR , comes also a more conservative timing... most of these cars have adaptive timing circuits with very well tuned knock sensors...
So sitting at 14.5:1 AFR, at WOT, in boost will definately mean a more coservative timing map than if you were running 12.5:1 ... this is on the same factory ECU with no timing corrections from the piggy back..
So between those 2 you lose alot of power in the tune alone. (This is the case with my C200 kompressor and i know what my next mod will be).
The trick around this is:
1- Change the target AFR for full throttle INSIDE the factory ECU ... GIAC might be able to do this, and charge a premium for it.
2- Get something called an O2 skewer... The AEM F/IC is effectively an O2 skewer and so is the simpler SplitSecond 'enricher'.
What these devices do is intercept and alter the factory wideband oxygen sensor signal going to the ECU... but they only do this at WOT... so the car can run 14.7:1 AFR as long as it likes, but when you go full throttle (or above a certain PSI) the interceptor lies to the factory ECU telling it that you are running too lean (say 16:1 AFR)... the ECU responds by adding 20% fuel till it thinks that it now sees 14.7:1 .... so now the ECU is fully happy.
But if you look at the uncorrected signal, and your ACTUAL air fuel ratio, you find it 12.5:1
so now you have TRICKED your factory ECU into WORKING WITH YOU to target a power friendly 12.5:1 AFR ... and it will continue to learn and tune TO it instead of AGAINST it as it did before..
The AEM F/IC also has the ability to alter injector duty cycle +/-50% and clamp map and MAS signals preventing the ECU from throwing 'too much pressure in manifold' check engine lights and activating limp modes.
__________________________________________________ ___
Putting all that aside.
If you're running factory cams (with overlap for a naturally aspirated car) and a factory header (for 50% less horsepower than you are making now) ... then you possibly have your supercharger fighting against 3 to 5psi of exhaust back pressure in the higher RPM ranges...
With overlap, both intake and exhaust valves are open... on naturally aspirated cars the inertia of the 'fluid' exhaust leaving the cylinder helps pull in more 'fluid' intake air during overlap... and this improves volumetric efficiency at higher rpms...
When you go supercharged and you start to overwhelm your exhaust flow capacity, you can build up a good 3 to 5 psi of exhaust back pressure in the manifolds (especially if you have close coupled cat converters integrated into the manifold) and so when both intake and exhaust valves open at the same time during overlap... you have 6psi of intake pressure (your supercharger) faced by say 3psi of exhaust back pressure (your headers) and that eventually leaves you with only 6-3=3 Psi of boost.
If you're still on stock cams and headers ... I'd swap out for higher flow large bore supercharger headers first.
Then I'd get intercooled (i don't think the VF kit is intercooled)
THEN and only then will I up the boost.
That's the best upgrade route for you ...
what rsalicrup is talking about is mostly cars equipped with wideband oxygen sensors from the factory... These cars for example target a lean air fuel ratio (even in boost for factory supercharged and turbocharged cars)...
If you put a piggy back controller on it, and add in some ~20% fueling to go from 14.5:1 AFR to around 12.5:1 AFR (which takes you from peak effeciency to peak horspower when you go WOT) ... then you find that the car dyno's great and makes a nice bump up in power...
Drive the car around for an hour... redyno it, and you'll find that the ECU has used it's longterm and short term fuel trims to dial out your +20% with a -20% fuel trim correction because it reads the factory wideband sensor and KNOWS that you are not sitting at the correct factory set AFR.
Now with this leaner AFR , comes also a more conservative timing... most of these cars have adaptive timing circuits with very well tuned knock sensors...
So sitting at 14.5:1 AFR, at WOT, in boost will definately mean a more coservative timing map than if you were running 12.5:1 ... this is on the same factory ECU with no timing corrections from the piggy back..
So between those 2 you lose alot of power in the tune alone. (This is the case with my C200 kompressor and i know what my next mod will be).
The trick around this is:
1- Change the target AFR for full throttle INSIDE the factory ECU ... GIAC might be able to do this, and charge a premium for it.
2- Get something called an O2 skewer... The AEM F/IC is effectively an O2 skewer and so is the simpler SplitSecond 'enricher'.
What these devices do is intercept and alter the factory wideband oxygen sensor signal going to the ECU... but they only do this at WOT... so the car can run 14.7:1 AFR as long as it likes, but when you go full throttle (or above a certain PSI) the interceptor lies to the factory ECU telling it that you are running too lean (say 16:1 AFR)... the ECU responds by adding 20% fuel till it thinks that it now sees 14.7:1 .... so now the ECU is fully happy.
But if you look at the uncorrected signal, and your ACTUAL air fuel ratio, you find it 12.5:1
so now you have TRICKED your factory ECU into WORKING WITH YOU to target a power friendly 12.5:1 AFR ... and it will continue to learn and tune TO it instead of AGAINST it as it did before..
The AEM F/IC also has the ability to alter injector duty cycle +/-50% and clamp map and MAS signals preventing the ECU from throwing 'too much pressure in manifold' check engine lights and activating limp modes.
__________________________________________________ ___
Putting all that aside.
If you're running factory cams (with overlap for a naturally aspirated car) and a factory header (for 50% less horsepower than you are making now) ... then you possibly have your supercharger fighting against 3 to 5psi of exhaust back pressure in the higher RPM ranges...
With overlap, both intake and exhaust valves are open... on naturally aspirated cars the inertia of the 'fluid' exhaust leaving the cylinder helps pull in more 'fluid' intake air during overlap... and this improves volumetric efficiency at higher rpms...
When you go supercharged and you start to overwhelm your exhaust flow capacity, you can build up a good 3 to 5 psi of exhaust back pressure in the manifolds (especially if you have close coupled cat converters integrated into the manifold) and so when both intake and exhaust valves open at the same time during overlap... you have 6psi of intake pressure (your supercharger) faced by say 3psi of exhaust back pressure (your headers) and that eventually leaves you with only 6-3=3 Psi of boost.
If you're still on stock cams and headers ... I'd swap out for higher flow large bore supercharger headers first.
Then I'd get intercooled (i don't think the VF kit is intercooled)
THEN and only then will I up the boost.
That's the best upgrade route for you ...
A couple of corrections are warranted:
NO ENGINE is tuned, stock or othewiise, boosted or not for a 14.5:1 a/f ratio at WOT. That would quickly destroy any engine. WOT is what you are tuning for and not closed loop where the O2 sensors will manage the fueling.
Secondly, the headers on the car are not the bottleneck of exhaust flow. Although flow will be slightly improved moving using some different headers, it will immeasurable as far a reducing exhaust back pressure fighting the boost. Installing freer flowing headers without changing the flow after them, can often decrease the engine's performance.
Last edited by 1999Porsche911; 09-28-2009 at 08:58 AM.
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#8
09-28-2009, 09:02 AM
Disagree with you totally....
Check a dyno log of a subaru WRX at WOT
Check a dyno log of a C200 Kompressor at WOT...
unfortunately Lots of cars run 14.5:1 at WOT nowadays and to make this happen a lot of timing is being pulled out and a lot of power is being wasted
Check a dyno log of a subaru WRX at WOT
Check a dyno log of a C200 Kompressor at WOT...
unfortunately Lots of cars run 14.5:1 at WOT nowadays and to make this happen a lot of timing is being pulled out and a lot of power is being wasted
#9
09-28-2009, 09:14 AM
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Join Date: Aug 2004
Location: Chicagoland
Posts: 2,134
Rep Power: 122 I can't check since each of those engines didn't finish the dyno run since the rods bent.
Please post some of these charts for us since they are so common.
#11
09-28-2009, 10:05 AM
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Join Date: Aug 2004
Location: Chicagoland
Posts: 2,134
Rep Power: 122 All those charts show is a/f ratio at idle.
#12
09-28-2009, 10:10 AM
you didn't read the whole thingsomewhere in there it says "so the only time the ecu goes into open loop is off throttle"
the answer is yes
the code in the ECU switches to open loop at 105% throttle (never switches over).
Attached
WRX dyno clearly holding 13:1 up to 4000 ... in boost
C230 Kompressor clearly holding 14:1 or leaner up to 4500 ... in boost ... remember this is a kompressor ... it can boost off idle
#13
09-28-2009, 10:28 AM
Registered User
Join Date: Aug 2004
Location: Chicagoland
Posts: 2,134
Rep Power: 122 you didn't read the whole thingsomewhere in there it says "so the only time the ecu goes into open loop is off throttle"
the answer is yes
the code in the ECU switches to open loop at 105% throttle (never switches over).
Attached
WRX dyno clearly holding 13:1 up to 4000 ... in boost
C230 Kompressor clearly holding 14:1 or leaner up to 4500 ... in boost ... remember this is a kompressor ... it can boost off idle
Well, their answer is wrong. Also your chart proves that your a/f fuel ratio gets richer as you go into WOT. First chart continues to get richer until it reaches about 11.5:1.
#14
09-28-2009, 10:29 AM
The stock engine has 11.5 Compression ratio. Based on experience, increasing the boost to 10psi with be a costly mistake based on the C/R. You will have denotation problems, if you are lucky enough to have the ECU catch them, it will reduce the timing to the point it will not be fun to drive. And they are right about the valve overlap on the stock cams. There is a reason the factory didn't turbo this engine.
#15
09-28-2009, 10:30 AM
Join Date: Aug 2009
Location: De Pere, Wisconsin
Posts: 119
Rep Power: 20 The stock engine has 11.5 Compression ratio. Based on experience, increasing the boost to 10psi with be a costly mistake based on the C/R. You will have denotation problems, if you are lucky enough to have the ECU catch them, it will reduce the timing to the point it will not be fun to drive. And they are right about the valve overlap on the stock cams. There is a reason the factory didn't turbo this engine.