Which MAF to go with?
01-26-2006, 06:19 PM
#91
Racer
Originally Posted by lart951
Yes it is nice to have aboard Andrew. I am also looking at spend some pesos with you.
About shipping is it expensive from UK to California?
About shipping is it expensive from UK to California?Any prices we quote are inclusive of shipping to any USA mainland state. Hence, our Rennlist buy price on the MAF of $849.95 is fully inclusive shipped to your door in CA.
Enjoy the rest of the day!
Regards,
Andrew
ProMAX Motorsport
01-26-2006, 07:44 PM
#92
Pro
Originally Posted by promax_motorsport
Hi John,
Thank you! I'll get in touch with you when I am next in Orlando. Should be sometime during February!
Is the 422 still in Ireland? Do you think you'll ever be able to persuade the authorities to let you bring it in?
Regards,
Andrew
Thank you! I'll get in touch with you when I am next in Orlando. Should be sometime during February!
Is the 422 still in Ireland? Do you think you'll ever be able to persuade the authorities to let you bring it in?
Regards,
Andrew
The car is still in Ireland and I've resigned to the fact it's not worth the crazy red tape hassle trying to bring it over here......no worries though as my wife and i will be living over there for 6 months of the year anyway so I'll still get to drive my baby!
Look forward to meeting up with you for a few beers when you are over in fl again
John.
01-27-2006, 02:20 AM
#93
Burning Brakes
This was the most interesting thread I've read in a long time. Ironically my Vitesse MAF and Piggyback is due to arrive UPS tomorrow to be mated with the K27/8 on the workbench (and then into the car of course). I cannot wait 'til the weekend !!
01-27-2006, 05:11 AM
#94
Burning Brakes
Originally Posted by brad-cam
This was the most interesting thread I've read in a long time. Ironically my Vitesse MAF and Piggyback is due to arrive UPS tomorrow to be mated with the K27/8 on the workbench (and then into the car of course). I cannot wait 'til the weekend !!
Tony
01-27-2006, 04:32 PM
#95
Instructor
Originally Posted by fast951
951 DME too slow? It is slower than late style DMEs, but it's fast enough to handle all the tasks at hand.
You're using hitachi maf - why does Porsche AG use Bosch?
01-27-2006, 05:08 PM
#96
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Originally Posted by turbinek
Just to get that right: 80's high tech like DME can handle x as much data more than it was designed for? (considering the inexact and to 4'500 rpm limited information from the afm - the maf delivers exact info and much more of it)
You're using hitachi maf - why does Porsche AG use Bosch?
You're using hitachi maf - why does Porsche AG use Bosch?
I would think Porsche uses Bosch for the MAFs because they use Bosch for just about every engine electronic device in their cars and I'm sure Bosch codes their DMEs around their MAF. Or they know that Ford uses the Hitachis and just can't lower themselves to that level.
01-27-2006, 06:59 PM
#97
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Originally Posted by turbinek
Just to get that right: 80's high tech like DME can handle x as much data more than it was designed for? (considering the inexact and to 4'500 rpm limited information from the afm - the maf delivers exact info and much more of it)
That makes it possible for the DME code just to call the ADC time by time to get the current air flow in a precise range.
That is difficult with the MAF. This sensor is much more sensible and also measures the pulsation in the air flow. So you can not just peek with the ADC into the MAF to get airflow information. You have to collect the values over a time frame to get the real flow. And that is difficult with the DME code designed for the AFM.
Here is a picture that shows the differences (Yellow=MAF, Blue=AFM, Magenta=FT Signal):
The throttle is opened suddenly and the full pulsation is send to the sensors. The AFM can work with that - the MAF measures the real flow. You can even count the pulsation waves to get the rpm..
And this is also a good benchmark for MAF implementations. Just open the throttle at idle speed completley and see what happens...
Btw: I can not see any technical differences between Siemens, Bosch or Hitachi MAFs. All are available in different sizes and all map the airflow to a 0-5V output voltage. The Bosch MAF has the advantage of a AFM compatible NTC build in.
And the capability to measure backflow makes it a perfect device for the installation with the BOV placed so close to the sensor.
01-27-2006, 07:09 PM
#98
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Transaxle, some good data, however as you know not all MAF sensors are the same or built the same. Some are noisier than others.. etc.. Without getting into too many technical issues (there are many items to talk about, but it 6pm on Friday 
)..
From experience, the DME works just fine with the software we use.. The MAF works fine with our software... the best proof is the end-user that loves the product, and none of the problems that can be caused by your description above.. At least not with the Vitesse MAF.
).. From experience, the DME works just fine with the software we use.. The MAF works fine with our software... the best proof is the end-user that loves the product, and none of the problems that can be caused by your description above.. At least not with the Vitesse MAF.
01-27-2006, 07:27 PM
#99
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Originally Posted by fast951
From experience, the DME works just fine with the software we use.. The MAF works fine with our software... the best proof is the end-user that loves the product, and none of the problems that can be caused by your description above.. At least not with the Vitesse MAF.
Btw: Here it's Saturday 12:30 am - Good night...
01-27-2006, 09:42 PM
#100
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Originally Posted by TT
Is that Huntley model an old bullet style? They are very position sensitive, don't like bends near the output, and like a long intake tract to smooth out airflow. When you close the throttle plate you will get reversion. The old bullets would not tolerate this very well and the MAF output would go to 0V and stay there until the flow was reestablished.
The position of the sample tube in the MAF affects this behavior. The air flow through a pipe is fastest at the center and slows parabolically towards the wall of the pipe. The sample tube for the bullets is near the wall where the flow is slowest and more dependent on positioning near bends. The sample tubes for the new Hitachi and the Bosch HFM units are towards the center of the tube where the flow rate is highest which makes them fairly position independent and bend tolerant.
As to the dynamic range, the stock AFMs were calibrated to use the voltage range from .8V to 4.8V for the 951 and 1.1V to 4.8V for the 944. The Vitesse MAF uses pretty much the whole 0-5V range so we gain back some dynamic range when selecting a large one-size-fits-all MAF. The 944NA is my daily driver and I have no problems with running the Vitesse 951 MAF at cruise or idle. I've actually run larger MAFs on the 944NA than the current kit MAF.
Good thing with the early chips is that Bosch didn't have much room for the programming and maps, much less any copyright markings. I have never seen any copyright markings on a DME, chip, or in the code for the 944/951 series. I have seen the patents for the Bosch engine control systems though, fairly generic beasts.
The position of the sample tube in the MAF affects this behavior. The air flow through a pipe is fastest at the center and slows parabolically towards the wall of the pipe. The sample tube for the bullets is near the wall where the flow is slowest and more dependent on positioning near bends. The sample tubes for the new Hitachi and the Bosch HFM units are towards the center of the tube where the flow rate is highest which makes them fairly position independent and bend tolerant.
As to the dynamic range, the stock AFMs were calibrated to use the voltage range from .8V to 4.8V for the 951 and 1.1V to 4.8V for the 944. The Vitesse MAF uses pretty much the whole 0-5V range so we gain back some dynamic range when selecting a large one-size-fits-all MAF. The 944NA is my daily driver and I have no problems with running the Vitesse 951 MAF at cruise or idle. I've actually run larger MAFs on the 944NA than the current kit MAF.
Good thing with the early chips is that Bosch didn't have much room for the programming and maps, much less any copyright markings. I have never seen any copyright markings on a DME, chip, or in the code for the 944/951 series. I have seen the patents for the Bosch engine control systems though, fairly generic beasts.
01-27-2006, 11:19 PM
#101
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Originally Posted by Tom M'Guinn
TT- here is a picture of the Huntley Stage 4 inside -- not sure if it is "bullet style" but it sure sounds like what you describe...
01-27-2006, 11:56 PM
#102
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Originally Posted by Transaxle
Yep - that is exactly the point where the DME is in difficulties. The AFM is a well designed mechanical sensor with a great pulsation filter built in. It cancels out backfire and pulsation with the design of the flap where opposite forces work on the air vane.
That makes it possible for the DME code just to call the ADC time by time to get the current air flow in a precise range.
That is difficult with the MAF. This sensor is much more sensible and also measures the pulsation in the air flow. So you can not just peek with the ADC into the MAF to get airflow information. You have to collect the values over a time frame to get the real flow. And that is difficult with the DME code designed for the AFM.
That makes it possible for the DME code just to call the ADC time by time to get the current air flow in a precise range.
That is difficult with the MAF. This sensor is much more sensible and also measures the pulsation in the air flow. So you can not just peek with the ADC into the MAF to get airflow information. You have to collect the values over a time frame to get the real flow. And that is difficult with the DME code designed for the AFM.
Originally Posted by Transaxle
Btw: I can not see any technical differences between Siemens, Bosch or Hitachi MAFs. All are available in different sizes and all map the airflow to a 0-5V output voltage. The Bosch MAF has the advantage of a AFM compatible NTC build in.
01-28-2006, 05:29 AM
#103
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Originally Posted by TT
The DME has no difficulty reading the MAF signal properly. The E36 M3s used the Bosch HFM MAFs. Neither the FY95 Bosch DME nor the later model Siemens DME perform any extra signal processing on the MAF input signal other than read the A/D value and calculate the flow. The 951 DME performs no differently..
If you look into the ML3.1 code, you see 5 calls in the mainloop to the ADC function to update the current status. In the M2.10 you see a timer function that collects permanently MAF values to provide a average mass flow value.
Again - I don't say that something is good or bad. I was just asked for information about my MAF design and I just want explain why I did it my way.
Originally Posted by TT
The Bosch MAFs tend to place the usable air flow range output voltage over the 1 - 5v range, they did the same with the VAFs. Hitachi's can be obtained that spread the usable measurement output over just about the whole 0-5V range, it may not seem like much but every bit helps when using an 8-bit A/D. I can get Hitachi units that will measure over 3000KG/Hr, I haven't seen any Bosch units capable of that. The new Hitachi MAFs come with a built-in temp sensor too, using it with the 951 DME is not a problem.
The range of a MAF is a function of it`s diameter.
Anyway - there are always different ways to design a solution. I love to discuss and exchange the ideas behind the design - not to debate what is better or worse.
01-28-2006, 05:37 AM
#104
Instructor
I enjoy really a lot how things are discussed here . Seems there are many roads leading to Rome. The choice is between the goals set:
racing go by vitesse
make your 951 more updated scivision
unless there is no stock looking style from John.
. Seems there are many roads leading to Rome. The choice is between the goals set:racing go by vitesse
make your 951 more updated scivision
unless there is no stock looking style from John.
01-28-2006, 11:13 AM
#105
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Originally Posted by turbinek
I enjoy really a lot how things are discussed here . Seems there are many roads leading to Rome. The choice is between the goals set:
racing go by vitesse
make your 951 more updated scivision
unless there is no stock looking style from John.
. Seems there are many roads leading to Rome. The choice is between the goals set:racing go by vitesse
make your 951 more updated scivision
unless there is no stock looking style from John.
Vitesse MAF are used for racing on 400-500+rwhp and they are also driven normally around town by 99.8% of our customers. So for racing or cruising we deliver!