another stupid thread about MAFs
04-05-2011, 08:55 PM
#196
Race Car
Those are good points and I would agree to a point. I have certainly maxxed out a modified afm myself. Josh has also done some comparisons on his flowbench.
I believe a significant difference between what you see vs the 951 crowd is that a small displacement turbocharged engine benefits greatly to added airflow Pre spoolup. I fully agree that if the tunes are maximized given the same pressure, rpm, afr etc that ther would not be a difference in power. Iirc around 33 pounds per minute the afm becomes a restriction so under that the only difference would be response time regarding turbo spool.
I have switched back and forth and there is a noticeable difference. Josh has done the same and had the same results.
I believe a significant difference between what you see vs the 951 crowd is that a small displacement turbocharged engine benefits greatly to added airflow Pre spoolup. I fully agree that if the tunes are maximized given the same pressure, rpm, afr etc that ther would not be a difference in power. Iirc around 33 pounds per minute the afm becomes a restriction so under that the only difference would be response time regarding turbo spool.
I have switched back and forth and there is a noticeable difference. Josh has done the same and had the same results.
04-05-2011, 09:46 PM
#197
My only point is you really need to do your homework. And in the 951 your results do seem to indicate a air flow restriction and with a turbo that's understandable.
So in your case the MAF helps air flow but so would a larger AFM, not saying I'd pick a larger AFM over MAF. Plus the MAFs are cheaper.
So in your case the MAF helps air flow but so would a larger AFM, not saying I'd pick a larger AFM over MAF. Plus the MAFs are cheaper.
Those are good points and I would agree to a point. I have certainly maxxed out a modified afm myself. Josh has also done some comparisons on his flowbench.
I believe a significant difference between what you see vs the 951 crowd is that a small displacement turbocharged engine benefits greatly to added airflow Pre spoolup. I fully agree that if the tunes are maximized given the same pressure, rpm, afr etc that ther would not be a difference in power. Iirc around 33 pounds per minute the afm becomes a restriction so under that the only difference would be response time regarding turbo spool.
I have switched back and forth and there is a noticeable difference. Josh has done the same and had the same results.
I believe a significant difference between what you see vs the 951 crowd is that a small displacement turbocharged engine benefits greatly to added airflow Pre spoolup. I fully agree that if the tunes are maximized given the same pressure, rpm, afr etc that ther would not be a difference in power. Iirc around 33 pounds per minute the afm becomes a restriction so under that the only difference would be response time regarding turbo spool.
I have switched back and forth and there is a noticeable difference. Josh has done the same and had the same results.
04-06-2011, 11:46 AM
#199
Three Wheelin'
Well It's not like people are being forced to give up the AFM, my understanding is that the AFM is not a problem until your pushing above 400 hp.
I don't think the thread is trying to be derailed, lot's of interesting questions being asked and good info here. Obviously the drive ability of the stock AFM can and has been improved.
When I got my 89, 951 MAX chipped, 18 lbs of boost, 55's, 3 bar FPR, Catback etc, on boost it's a monster but if it's not at 3200 in 3rd, I got nothing! Apparently this can be improved and still keep the AFM . But I'm pitching it some will, some won't. It's nice to have options.
The AFM works no question, it's just old tech. I'd just state, that if the AFM is so great, why is it no longer iin use?
I don't think the thread is trying to be derailed, lot's of interesting questions being asked and good info here. Obviously the drive ability of the stock AFM can and has been improved.
When I got my 89, 951 MAX chipped, 18 lbs of boost, 55's, 3 bar FPR, Catback etc, on boost it's a monster but if it's not at 3200 in 3rd, I got nothing! Apparently this can be improved and still keep the AFM . But I'm pitching it some will, some won't. It's nice to have options.
The AFM works no question, it's just old tech. I'd just state, that if the AFM is so great, why is it no longer iin use?
04-06-2011, 02:59 PM
#200
Nordschleife Master
Well It's not like people are being forced to give up the AFM, my understanding is that the AFM is not a problem until your pushing above 400 hp.
I don't think the thread is trying to be derailed, lot's of interesting questions being asked and good info here. Obviously the drive ability of the stock AFM can and has been improved.
When I got my 89, 951 MAX chipped, 18 lbs of boost, 55's, 3 bar FPR, Catback etc, on boost it's a monster but if it's not at 3200 in 3rd, I got nothing! Apparently this can be improved and still keep the AFM . But I'm pitching it some will, some won't. It's nice to have options.
The AFM works no question, it's just old tech. I'd just state, that if the AFM is so great, why is it no longer iin use?
I don't think the thread is trying to be derailed, lot's of interesting questions being asked and good info here. Obviously the drive ability of the stock AFM can and has been improved.
When I got my 89, 951 MAX chipped, 18 lbs of boost, 55's, 3 bar FPR, Catback etc, on boost it's a monster but if it's not at 3200 in 3rd, I got nothing! Apparently this can be improved and still keep the AFM . But I'm pitching it some will, some won't. It's nice to have options.
The AFM works no question, it's just old tech. I'd just state, that if the AFM is so great, why is it no longer iin use?
Rogue posted a graph on here a while back, and of the 6 or 7 AFMs he tested on his flow bench, none of them were on the factory curve anymore, and a few of them were quite far off.
They are a 20+ year old device that relies on a spring, and friction to function properly.
Every 951 would benefit from a True MAF kit.
04-06-2011, 03:47 PM
#201
Drive-by provocation guy
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04-06-2011, 04:54 PM
#202
Agree 100%! I also have seen that no 2 AFMs in the 3.2L 911 are the same. In fact I spend time dialing in the AirCurve on the old AFMs from data (AFR) from a WOT run. You can re-adjust the AFM curve to match your desired result but it's a huge pain! Here I agree that converting to MAF makes this so much easier.
That is kind of the issue... AFM's DO NOT work anymore. They make your car run, but they are not accurate.
Rogue posted a graph on here a while back, and of the 6 or 7 AFMs he tested on his flow bench, none of them were on the factory curve anymore, and a few of them were quite far off.
They are a 20+ year old device that relies on a spring, and friction to function properly.
Every 951 would benefit from a True MAF kit.
Rogue posted a graph on here a while back, and of the 6 or 7 AFMs he tested on his flow bench, none of them were on the factory curve anymore, and a few of them were quite far off.
They are a 20+ year old device that relies on a spring, and friction to function properly.
Every 951 would benefit from a True MAF kit.
04-06-2011, 05:17 PM
#203
Race Car
If you continue to do that for the 911 community you may want to contact Josh about flowing your afms for you to get an accurate curve for the particular afm. With that data you may be able to get an accurate tune without the effort of all the wot runs??
04-06-2011, 05:27 PM
#204
Three Wheelin'
That is kind of the issue... AFM's DO NOT work anymore. They make your car run, but they are not accurate.
Rogue posted a graph on here a while back, and of the 6 or 7 AFMs he tested on his flow bench, none of them were on the factory curve anymore, and a few of them were quite far off.
They are a 20+ year old device that relies on a spring, and friction to function properly.
Every 951 would benefit from a True MAF kit.
Rogue posted a graph on here a while back, and of the 6 or 7 AFMs he tested on his flow bench, none of them were on the factory curve anymore, and a few of them were quite far off.
They are a 20+ year old device that relies on a spring, and friction to function properly.
Every 951 would benefit from a True MAF kit.
It's nice to have projects
04-06-2011, 05:49 PM
#205
Race Car
Not to confuse the issue.... But unless you are using a true maf setup I think using the afm is more stable than the alternative of massaging a maf (even map) signal to emulate an afm curve.
When using an old afm IMO you have to make a decision as to what you are tuning for imo. Either max hp or drivability. There seem to be very few that have a solid factory curve. The difference may be slight but also may be huge.
Just thought I'd mention that since it looked as though afms were being thrown under the bus. They have their place too, just a little more difficult to make sure tuning is accurate
When using an old afm IMO you have to make a decision as to what you are tuning for imo. Either max hp or drivability. There seem to be very few that have a solid factory curve. The difference may be slight but also may be huge.
Just thought I'd mention that since it looked as though afms were being thrown under the bus. They have their place too, just a little more difficult to make sure tuning is accurate
04-06-2011, 06:10 PM
#206
What would be nice is if we had the factory specs on the voltage vs. air flow. If we had the factory AFM curve specs then anyone with a good flow bench could recalibrate the AFM. A service like this would be useful. I have specs for some of the Bosch MAF Hot Film sensors but have never seen an official spec on a AFM. Another way to maybe get the specs is to find a new Bosch replacement AFM and flow bench it. Or find several older ones and find a average.
Not to confuse the issue.... But unless you are using a true maf setup I think using the afm is more stable than the alternative of massaging a maf (even map) signal to emulate an afm curve.
When using an old afm IMO you have to make a decision as to what you are tuning for imo. Either max hp or drivability. There seem to be very few that have a solid factory curve. The difference may be slight but also may be huge.
Just thought I'd mention that since it looked as though afms were being thrown under the bus. They have their place too, just a little more difficult to make sure tuning is accurate
When using an old afm IMO you have to make a decision as to what you are tuning for imo. Either max hp or drivability. There seem to be very few that have a solid factory curve. The difference may be slight but also may be huge.
Just thought I'd mention that since it looked as though afms were being thrown under the bus. They have their place too, just a little more difficult to make sure tuning is accurate
04-06-2011, 06:12 PM
#207
Nordschleife Master
Not to confuse the issue.... But unless you are using a true maf setup I think using the afm is more stable than the alternative of massaging a maf (even map) signal to emulate an afm curve.
When using an old afm IMO you have to make a decision as to what you are tuning for imo. Either max hp or drivability. There seem to be very few that have a solid factory curve. The difference may be slight but also may be huge.
Just thought I'd mention that since it looked as though afms were being thrown under the bus. They have their place too, just a little more difficult to make sure tuning is accurate
When using an old afm IMO you have to make a decision as to what you are tuning for imo. Either max hp or drivability. There seem to be very few that have a solid factory curve. The difference may be slight but also may be huge.
Just thought I'd mention that since it looked as though afms were being thrown under the bus. They have their place too, just a little more difficult to make sure tuning is accurate
But, I think most would agree that its a choice between either of the 2 "true" MAF setups, or keeping the stock AFM. Converting a MAF signal to an AFM signal just doesn't give you the best of both worlds.
04-29-2011, 12:19 PM
#208
Three Wheelin'
Went to the Rogue site to see what's up. New info on the A tune is up! I'm not a current user , still running my MAX chipped 951( well when it runs!) with it's Jekyll and Hyde personality! All I can say is wow! Anybody still running the AFM and looking for a chip, needs to look at this!
Not gonna post a link, it's already here and if your to lazy to find the link, then your too lazy to install the kit anyway!
Not gonna post a link, it's already here and if your to lazy to find the link, then your too lazy to install the kit anyway!
