Modified intake, more cold air (hopefully) pics
07-01-2007, 06:09 PM
#91
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Bill,
The AFM is an airflow restrictor on the 964 airflow system . The AFM signal
is at full blast at around 4500 rpm. The measurement flap is wide open !
From there on the air flow is at the mercy of the AFM air flow ability ! The 964 has the same ,identical AFM as the 3.2 !!!!
Your measurements have demonstrated the problem .
Since those days air flow is measured by the MAF unit with Bosch DME software to suit . The power /air flow levels that MAF/DME can now accomodate have moved into huge levels on turbo models as an example .
I will leave Colin to persuade you that only Motec has this ability !!!
Couldnt resist that one !
Geoff
----------------------------------------------------------------
KS400200,the oldest 964 on Rennlist,unless you know differently !
The AFM is an airflow restrictor on the 964 airflow system . The AFM signal
is at full blast at around 4500 rpm. The measurement flap is wide open !
From there on the air flow is at the mercy of the AFM air flow ability ! The 964 has the same ,identical AFM as the 3.2 !!!!
Your measurements have demonstrated the problem .
Since those days air flow is measured by the MAF unit with Bosch DME software to suit . The power /air flow levels that MAF/DME can now accomodate have moved into huge levels on turbo models as an example .
I will leave Colin to persuade you that only Motec has this ability !!!
Couldnt resist that one !
Geoff
----------------------------------------------------------------
KS400200,the oldest 964 on Rennlist,unless you know differently !
07-01-2007, 09:27 PM
#92
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Thread Starter
I did all my testing upstream of the AFM, so its pressure drop is not in the numbers.
I was trying to see what the difference was with a cone filter mounted directly to the AFM and with it mounted to an extension to get it under the spoiler.
I kept the AFM out of the test, as most of us don't run a MAF setup, not did I have one to compare to.
I was trying to see what the difference was with a cone filter mounted directly to the AFM and with it mounted to an extension to get it under the spoiler.
I kept the AFM out of the test, as most of us don't run a MAF setup, not did I have one to compare to.
07-02-2007, 04:09 AM
#93
wsybert,
It sounds like swings and roundabouts, you gain a little here and loose a little there. But the 1st approx pipe program that I used suggested an average 0.2 lb difference at 380 cfm by adding a squared bend so at least we are getting similar magnitude results simulated and actual measurements. You may find that you are getting a little more pressure drop at the centre than at the edge of the pipe. How far into the pipe does your sensor go?
BR, Mark.
It sounds like swings and roundabouts, you gain a little here and loose a little there. But the 1st approx pipe program that I used suggested an average 0.2 lb difference at 380 cfm by adding a squared bend so at least we are getting similar magnitude results simulated and actual measurements. You may find that you are getting a little more pressure drop at the centre than at the edge of the pipe. How far into the pipe does your sensor go?
BR, Mark.
07-02-2007, 09:40 AM
#94
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wysbert,
I would have suspected that a straight pipe versus a 90 bend would be a reflection of the air flow through a restricted AFM ?
The 90 degree pipe should cause a laminar airflow problem for the air flow through the AFM ?
Then the problem that the straight pipe will be more affected by air temperature rise ?
Good luck with your investigations !! Looks like a big task to split out the problems .
Geoff
----------------------------------------------------------------
KS400200,the oldest 964 on Rennlist,unless you know differently !
I would have suspected that a straight pipe versus a 90 bend would be a reflection of the air flow through a restricted AFM ?
The 90 degree pipe should cause a laminar airflow problem for the air flow through the AFM ?
Then the problem that the straight pipe will be more affected by air temperature rise ?
Good luck with your investigations !! Looks like a big task to split out the problems .
Geoff
----------------------------------------------------------------
KS400200,the oldest 964 on Rennlist,unless you know differently !
07-02-2007, 06:34 PM
#95
Three Wheelin'
Typically its best to have 10 to 15 pipe diameters of straight tube before a sensor.
Otherwise the sensor can see alot of noise in its readings which you have to filter out.
Kirk
Otherwise the sensor can see alot of noise in its readings which you have to filter out.
Kirk
07-03-2007, 12:15 AM
#96
Pro
Thread Starter
Typically its best to have 10 to 15 pipe diameters of straight tube before a sensor.
Otherwise the sensor can see alot of noise in its readings which you have to filter out.
Otherwise the sensor can see alot of noise in its readings which you have to filter out.
...How far into the pipe does your sensor go?
It sounds like swings and roundabouts, you gain a little here and loose a little there.
07-03-2007, 11:20 AM
#97
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Rennlist Member
Geoff, going along with your logic, where does that leave the 'snorkel' air box inlet extension, as fitted to TTs / GT2s to get cool air from above the intercooler .. it is a smoothly rounded 90 degrees, and definitely reduces AIT ...
I run one on my VRam motor to get the cold air from the Aerokit engine cover inlets .. it has been remapped (at AMD .. ), yet last time on the dyno it was down from standard ..
cheers, Maurice
I run one on my VRam motor to get the cold air from the Aerokit engine cover inlets .. it has been remapped (at AMD .. ), yet last time on the dyno it was down from standard ..
cheers, Maurice
07-03-2007, 02:41 PM
#98
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Maurice ,
Sorry but the air flow debate is about the 964 ! My view is that the AFM at wide open is a significant part of the air flow situation .
You have the good 993tt extra intake trumpet . I suggested that the Peter quite a few years ago , together with the clutch breather hose output sent elsewhere ! Anything non restrictive or air temperature rising is good news for the inlet .
The 993 DME systems are right on top of ambient temperature / intake air temp . That all part of the motor safety system . The 993 runs a bit more advance than a 964 so all care was taken .
Thats why I find Motec with its usual ,no detonation control system ,a poor set up on the air cooled 911s ! That will get Colin going !!!
I would suggest that all power measurements need to be linked to the ambient temperature . Even though the Maha was running my companies logging system to compensate for temperature , that still leaves the DME to reduce the power level if it sees higher temperature !
None of this stuff is simple !!
Geoff
----------------------------------------------------------------
KS400200,the oldest 964 on Rennlist,unless you know differently !
Sorry but the air flow debate is about the 964 ! My view is that the AFM at wide open is a significant part of the air flow situation .
You have the good 993tt extra intake trumpet . I suggested that the Peter quite a few years ago , together with the clutch breather hose output sent elsewhere ! Anything non restrictive or air temperature rising is good news for the inlet .
The 993 DME systems are right on top of ambient temperature / intake air temp . That all part of the motor safety system . The 993 runs a bit more advance than a 964 so all care was taken .
Thats why I find Motec with its usual ,no detonation control system ,a poor set up on the air cooled 911s ! That will get Colin going !!!
I would suggest that all power measurements need to be linked to the ambient temperature . Even though the Maha was running my companies logging system to compensate for temperature , that still leaves the DME to reduce the power level if it sees higher temperature !
None of this stuff is simple !!
Geoff
----------------------------------------------------------------
KS400200,the oldest 964 on Rennlist,unless you know differently !
07-04-2007, 09:12 AM
#100
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Maurice,
What I said was public so go ahead . I am sure there are lots of 993 viewpoints for people to have a go at !!
Geoff
----------------------------------------------------------------
KS400200,the oldest 964 on Rennlist,unless you know differently !
What I said was public so go ahead . I am sure there are lots of 993 viewpoints for people to have a go at !!
Geoff
----------------------------------------------------------------
KS400200,the oldest 964 on Rennlist,unless you know differently !
