Boost vs. Timing -- Optimal Power?
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From: Virginia Beach, Virginia
I do set the boost first, it has to be set to something
but seriously, after I get the afr and timing dialed in for x boost, I increase boost and tweak timing/fuel to keep knock in check if I'm interested in running more.If you're raising boost and seeing a significantly leaner AFR something is is up with your fuel pressure. Our cars use a 1:1 rising rate fuel pressure regulator meaning as I increase boost 1psi , the fuel pressure rises 1psi as well. Also keep in mind that the stock MAF meters the extra air coming in when you raise boost. This signals the ECU to go into the proper load column and thus fuel setting.
bottom line..with proper tuning and adequate fuel supply you shouldn't be seeing a different AFR when you raise boost.
I do set the boost first, it has to be set to something but seriously, after I get the afr and timing dialed in for x boost, I increase boost and tweak timing/fuel to keep knock in check if I'm interested in running more.
If you're raising boost and seeing a significantly leaner AFR something is is up with your fuel pressure. Our cars use a 1:1 rising rate fuel pressure regulator meaning as I increase boost 1psi , the fuel pressure rises 1psi as well. Also keep in mind that the stock MAF meters the extra air coming in when you raise boost. This signals the ECU to go into the proper load column and thus fuel setting.
bottom line..with proper tuning and adequate fuel supply you shouldn't be seeing a different AFR when you raise boost.
but seriously, after I get the afr and timing dialed in for x boost, I increase boost and tweak timing/fuel to keep knock in check if I'm interested in running more.If you're raising boost and seeing a significantly leaner AFR something is is up with your fuel pressure. Our cars use a 1:1 rising rate fuel pressure regulator meaning as I increase boost 1psi , the fuel pressure rises 1psi as well. Also keep in mind that the stock MAF meters the extra air coming in when you raise boost. This signals the ECU to go into the proper load column and thus fuel setting.
bottom line..with proper tuning and adequate fuel supply you shouldn't be seeing a different AFR when you raise boost.
These are good timing numbers. You are following the MTBT principle. You run mimimum timing for the best torque w/o knock and not 1* more than that. The "Bubba" school of tuning believe that if a little advance is good, then a lot must be better. And the "tooner" starts cramming more timing down the engine's throat. When the ECU starts protesting and pulls timing, the "tooner" gets flustered and starts block tuning, collapsing the high and low octane ignition maps in the hope that this will stop the ECU from pulling timing. When that does not work, the "tooner" starts making excuses blaming the performance parts on the car. When you fix those and the knock continues, he simply gives up, declares the car a knocker and stops tuning.
This actually happened to my friend.
This actually happened to my friend.
Here's my methanol approach:
AFR 12.0 - 12.5
4* peak load / 19* redline
Set boost to whatever, if the timing/AFR cells are traced accurately (2 byte) then there is at least a 10 psi window of boost adjustment without going out of tune. For instance my AFR and timing is set whether I run 24 psi or 30 psi
AFR 12.0 - 12.5
4* peak load / 19* redline
Set boost to whatever, if the timing/AFR cells are traced accurately (2 byte) then there is at least a 10 psi window of boost adjustment without going out of tune. For instance my AFR and timing is set whether I run 24 psi or 30 psi
my 93 octane
AFR 11.2-11.6
6-7* peak load / 18* redline
Thats what my motor loves, im on 21psi stock VIII turbo and have sat out on roads for hours tuning that in. Its what feels best but as others have said differnt motors like differnt timing/AFR so try a bunch of combos out til you have what feels and performs best for your car
AFR 11.2-11.6
6-7* peak load / 18* redline
Thats what my motor loves, im on 21psi stock VIII turbo and have sat out on roads for hours tuning that in. Its what feels best but as others have said differnt motors like differnt timing/AFR so try a bunch of combos out til you have what feels and performs best for your car
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Joined: May 2007
Posts: 4
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From: Roy,WA
AFR has multiple effects that I haven't seen mentioned here yet.
AFR heavily effects Burn Rate inside the cylinder. A Leaner AFR is like adding timing in the sense that the burn will be completed sooner after TDC. The whole purpose of changing AFR and timing is to get Peak Cylinder Pressure at the best torque angle of the crank.
Some areas of the rpm range may benefit from a leaner AFR and low timing, while other may like a richer mixture with more timing. And this will change with cams and boost.
It is important to approach a tune with this mindset and experiment to find out what works best for the car.
AFR heavily effects Burn Rate inside the cylinder. A Leaner AFR is like adding timing in the sense that the burn will be completed sooner after TDC. The whole purpose of changing AFR and timing is to get Peak Cylinder Pressure at the best torque angle of the crank.
Some areas of the rpm range may benefit from a leaner AFR and low timing, while other may like a richer mixture with more timing. And this will change with cams and boost.
It is important to approach a tune with this mindset and experiment to find out what works best for the car.
my 93 octane
AFR 11.2-11.6
6-7* peak load / 18* redline
Thats what my motor loves, im on 21psi stock VIII turbo and have sat out on roads for hours tuning that in. Its what feels best but as others have said differnt motors like differnt timing/AFR so try a bunch of combos out til you have what feels and performs best for your car
AFR 11.2-11.6
6-7* peak load / 18* redline
Thats what my motor loves, im on 21psi stock VIII turbo and have sat out on roads for hours tuning that in. Its what feels best but as others have said differnt motors like differnt timing/AFR so try a bunch of combos out til you have what feels and performs best for your car
AFR has multiple effects that I haven't seen mentioned here yet.
AFR heavily effects Burn Rate inside the cylinder. A Leaner AFR is like adding timing in the sense that the burn will be completed sooner after TDC. The whole purpose of changing AFR and timing is to get Peak Cylinder Pressure at the best torque angle of the crank.
Some areas of the rpm range may benefit from a leaner AFR and low timing, while other may like a richer mixture with more timing. And this will change with cams and boost.
It is important to approach a tune with this mindset and experiment to find out what works best for the car.
AFR heavily effects Burn Rate inside the cylinder. A Leaner AFR is like adding timing in the sense that the burn will be completed sooner after TDC. The whole purpose of changing AFR and timing is to get Peak Cylinder Pressure at the best torque angle of the crank.
Some areas of the rpm range may benefit from a leaner AFR and low timing, while other may like a richer mixture with more timing. And this will change with cams and boost.
It is important to approach a tune with this mindset and experiment to find out what works best for the car.
If this is who I think it is, nice to see ya join us. I will be in touch with you via AIM on this very subject soon!
SQ aka jasper16g
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