MAP or MAF ??????????
07-11-2003, 12:02 PM
#31
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Most MAF systems which are on the market are NOT good, the only good ones are the one gururacing and vitesseracing are offering. All others with their 4 **** adjustments are a joke (even the "new digital" lindsey one). I don't understand why gururacing is only offering a full MAP kit but only a digital MAF upgrade and not a full kit as theirs sure sound like the best solution.
07-11-2003, 12:04 PM
#32
Whats a minor change? Talk 951 here. What is done exactly to a 951 engine (minor change). Are yo saying that after initial tuning after MAF is installed, you do some minor chamge and no mapping. Everything is ok. Just what doesthis minor change produce in performance? Or is this minor change so insignificant that it makes no difference?
I'm not aginst MAF systems. I think they are very good. Just cannnot see your point. A "minor" change may not require the MAP to be retuned either. It all depends on how minor and maybe how good the initial tune was. I still think you made a very broad statement that was to make your point. You have previously said of changing a Turbo etc. Is this what you mean by "minor". If we compare your MAF setup which I know nothing about to Guru's MAP system, I think this device has an O2 input. Would that not compensate for changes? I have always been trying to understand your point from the 951 perspective. The MAF units sold and the MAP units sold. Not in general. What use would that be.
As you said we do not agree. Well I do agree with you. I think MAF systems are very good. I have appreciated your comments and have learnt something here. I hope others have too.
I'm not aginst MAF systems. I think they are very good. Just cannnot see your point. A "minor" change may not require the MAP to be retuned either. It all depends on how minor and maybe how good the initial tune was. I still think you made a very broad statement that was to make your point. You have previously said of changing a Turbo etc. Is this what you mean by "minor". If we compare your MAF setup which I know nothing about to Guru's MAP system, I think this device has an O2 input. Would that not compensate for changes? I have always been trying to understand your point from the 951 perspective. The MAF units sold and the MAP units sold. Not in general. What use would that be.
As you said we do not agree. Well I do agree with you. I think MAF systems are very good. I have appreciated your comments and have learnt something here. I hope others have too.
07-11-2003, 12:19 PM
#33
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Crazyracer,
Today on the market, for the 951, there is no such a thing as "Digital MAF".
Digital MAFs do exists but none of them work on the 951 nor is designed to be used with the 951.
A "DIGITAL" MAF is a sensor that generates frequency. All MAFs, including the Vitesse one, are "ANALOG" MAF with an output in the range of (0-5Vdc).
So when you hear "Digital MAF" for the 951, it's just a marketing "sexy" word. They are not bad MAFs, just not "Digital".
Now, the signal massagers (PiggyBack, 4 **** devices...) you get with such MAF have electronics in them and are digital...
The bottom line, you are still dealing with an Analog MAF.
Today on the market, for the 951, there is no such a thing as "Digital MAF".
Digital MAFs do exists but none of them work on the 951 nor is designed to be used with the 951.
A "DIGITAL" MAF is a sensor that generates frequency. All MAFs, including the Vitesse one, are "ANALOG" MAF with an output in the range of (0-5Vdc).
So when you hear "Digital MAF" for the 951, it's just a marketing "sexy" word. They are not bad MAFs, just not "Digital".
Now, the signal massagers (PiggyBack, 4 **** devices...) you get with such MAF have electronics in them and are digital...
The bottom line, you are still dealing with an Analog MAF.
07-11-2003, 02:16 PM
#34
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"I don't understand why gururacing is only offering a full MAP kit but only a digital MAF upgrade and not a full kit as theirs sure sound like the best solution. "
We'll be offering a full MAF kit soon too! <img border="0" alt="[bigbye]" title="" src="graemlins/xyxwave.gif" /> The 'digital' part refers to the interceptor/controller, not the MAF-sensor itself. The 3D mapping capability of our InterceptLink box with Load vs. RPM references is light-years ahead of 4-**** analog adjusters which only does volt-in -> volt-out massaging through a voltage-divider array. Sometimes you need to adjust the same voltage up AND down depending upon the load and RPM you're running in. Anyway, we'll see if some users of our Digital-MAF upgrade can chime in.
As for an actual ditigal-MAF sensor, it's still analog really. Rather than a 0-5v (or 0-6v) signal, it uses a FSK-signal just like the 1st generation modems (2 different frequencies alternating with each other). Still an analog signal. I think a real digital-MAF sensor would be a device with a serial or USB connection that doesn't require a ADC on the receiving end and the EFI system would work with the received data directly.
Also we must separate turbo compressor-efficiency from the engine's VE-volumetric efficiency. These two gets lumped together when people make the sweeping statements of "more air at same 15psi boost". A more-efficient turbo will not provide more air at the same boost-level, it will just provide it at a lower temperature. And if you get a bigger turbo, it won't drop boost in the upper-RPMs like the stock one. So yes, it will provide more air at 6000rpm with 15psi boost compared to 10psi stock.
It's really the engine's VE that lets you flow more air at the same boost. By doing things like port & polishing the heads with larger valves and fully-contoured seats, cam-lift and timing changes, intake-manifold and TB upgrades, you can increase the high-RPM breathing capability of the engine. In effect boost-pressure is a measure of restrictions in the engine. The lower the restriction, the lower the boost-pressure for the same volume/mass of air flowed through the engine. Or conversely, for the same boost-pressure, you can flow through more air through a higher-VE engine.
Here's how the Honda deals with VE changes as its engine wears. The rings wear, the valve-seats wear (the valves don't wear-out, they have some coating that you can't even machine away). This results in blow-by and lower compression. It ALSO results in lower manifold vacuum at idle, which is picked up by the MAP sensor! The lower-sealing rings will also suck in less air and vacuum at all other operating zones and the MAP will pick this up and look up a different fuel-zone on the fuel-maps.
A more fruitful discussion rather than debating hardware of MAP vs. MAF, would be looking at the #2 tuning step. What features and tuning-tools do you want with a system that will allow you to make corrections on a dyno in the most precise manner in the least amount of time. In the end, that is what will benefit people the most in upgrading their cars. I've found that datalogging is an immense aid because it allows you to sit back and take your time to analyize the data and pick out exactly which RPM ranges you need to adjust.
Which relates to the "minor change" that fast951 has been referring. This is a limitation with the Motronic DME and its bizarre multiple-mapping scheme. Under full-throttle when the WOT fuel-map is being used, there's only so much adjustment that can be made by modifying the incoming air-flow signal (from a MAF or a MAP). Beyond this point, you need to re-map the chips themselves.
We'll be offering a full MAF kit soon too! <img border="0" alt="[bigbye]" title="" src="graemlins/xyxwave.gif" /> The 'digital' part refers to the interceptor/controller, not the MAF-sensor itself. The 3D mapping capability of our InterceptLink box with Load vs. RPM references is light-years ahead of 4-**** analog adjusters which only does volt-in -> volt-out massaging through a voltage-divider array. Sometimes you need to adjust the same voltage up AND down depending upon the load and RPM you're running in. Anyway, we'll see if some users of our Digital-MAF upgrade can chime in.
As for an actual ditigal-MAF sensor, it's still analog really. Rather than a 0-5v (or 0-6v) signal, it uses a FSK-signal just like the 1st generation modems (2 different frequencies alternating with each other). Still an analog signal. I think a real digital-MAF sensor would be a device with a serial or USB connection that doesn't require a ADC on the receiving end and the EFI system would work with the received data directly.
Also we must separate turbo compressor-efficiency from the engine's VE-volumetric efficiency. These two gets lumped together when people make the sweeping statements of "more air at same 15psi boost". A more-efficient turbo will not provide more air at the same boost-level, it will just provide it at a lower temperature. And if you get a bigger turbo, it won't drop boost in the upper-RPMs like the stock one. So yes, it will provide more air at 6000rpm with 15psi boost compared to 10psi stock.
It's really the engine's VE that lets you flow more air at the same boost. By doing things like port & polishing the heads with larger valves and fully-contoured seats, cam-lift and timing changes, intake-manifold and TB upgrades, you can increase the high-RPM breathing capability of the engine. In effect boost-pressure is a measure of restrictions in the engine. The lower the restriction, the lower the boost-pressure for the same volume/mass of air flowed through the engine. Or conversely, for the same boost-pressure, you can flow through more air through a higher-VE engine.
Here's how the Honda deals with VE changes as its engine wears. The rings wear, the valve-seats wear (the valves don't wear-out, they have some coating that you can't even machine away). This results in blow-by and lower compression. It ALSO results in lower manifold vacuum at idle, which is picked up by the MAP sensor! The lower-sealing rings will also suck in less air and vacuum at all other operating zones and the MAP will pick this up and look up a different fuel-zone on the fuel-maps.
A more fruitful discussion rather than debating hardware of MAP vs. MAF, would be looking at the #2 tuning step. What features and tuning-tools do you want with a system that will allow you to make corrections on a dyno in the most precise manner in the least amount of time. In the end, that is what will benefit people the most in upgrading their cars. I've found that datalogging is an immense aid because it allows you to sit back and take your time to analyize the data and pick out exactly which RPM ranges you need to adjust.
Which relates to the "minor change" that fast951 has been referring. This is a limitation with the Motronic DME and its bizarre multiple-mapping scheme. Under full-throttle when the WOT fuel-map is being used, there's only so much adjustment that can be made by modifying the incoming air-flow signal (from a MAF or a MAP). Beyond this point, you need to re-map the chips themselves.
07-11-2003, 03:03 PM
#35
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Danno, youu bring out some very good points. These same points indicates that my theory of MAF compensation is valid.
Let's say you tune a car at 15psi boost. The engine gets tires, and as you stated, the Volumetric Efficiency drops. With Lower Volumetric effieciency (Ve), as you stated, your engine is flowing less air at the same boost.
Now we have Less Air, Same boost level. The MAP will send the DME the same signal as it always did. It's the signal for boost (which has not changed). Since the engine is flowing less air, the DME has no idea as it still receiving the same signal as it did when the engine was tuned. This leads me to conclude that the MAP is not compensating for a change in Ve.
Now if we take the same application with a MAF. When Ve drops, the air flowing decreases. The MAF is measuring the MAss of Air and will send the DME the appropriate signal (reflecting the change). Now the DME is getting the correct information.
I agree with you 100% that initial tuning is very important. Also the tools that we provide the end user to fine tune his car are just as important. Ease of use, Data Logging... The more user friendly a tool is the more it is used...
Data Logging and the ability to playback the logged data in a manner where the user can identify areas that need attention is very important.
I think people using such tools need to junp in. Or perhaps we should start a new thread and label it. "Tuning Tools"???
Let's say you tune a car at 15psi boost. The engine gets tires, and as you stated, the Volumetric Efficiency drops. With Lower Volumetric effieciency (Ve), as you stated, your engine is flowing less air at the same boost.
Now we have Less Air, Same boost level. The MAP will send the DME the same signal as it always did. It's the signal for boost (which has not changed). Since the engine is flowing less air, the DME has no idea as it still receiving the same signal as it did when the engine was tuned. This leads me to conclude that the MAP is not compensating for a change in Ve.
Now if we take the same application with a MAF. When Ve drops, the air flowing decreases. The MAF is measuring the MAss of Air and will send the DME the appropriate signal (reflecting the change). Now the DME is getting the correct information.
I agree with you 100% that initial tuning is very important. Also the tools that we provide the end user to fine tune his car are just as important. Ease of use, Data Logging... The more user friendly a tool is the more it is used...
Data Logging and the ability to playback the logged data in a manner where the user can identify areas that need attention is very important.
I think people using such tools need to junp in. Or perhaps we should start a new thread and label it. "Tuning Tools"???
07-11-2003, 03:21 PM
#36
Race Director
"The engine gets tires, and as you stated, the Volumetric Efficiency drops. With Lower Volumetric effieciency (Ve), as you stated, your engine is flowing less air at the same boost."
Ok, maybe me using the Honda example was not appropriate because NA vs Turbo cars behave a little differently. The specific-output HP/Ltr of the engine may get lower with wear, but VE doesn't change as much. On an NA engine, flow is initiated by the pistons sucking in air and VE changes as the rings' ability to pull air in changes.
On a Turbo engine, flow is initiated by the turbo pushing air into the engine. Regardless of the wear-rates of the rings or valves, that turbo is going to be cramming in the same amount of air regardless of the condition of the rings and valves. Power is then just a matter of whether the rings and valves can contain that combustion. As a Turbo engine wears, its VE won't change much even though its specfic output will. What does make a big different in VE is changing the actual components such as the diameter, length and shape of the intake-runners, porting & polishing the head, valve-work, etc.
When talking about VE changes, I think we need to refer to different engine configurations, such as different parts. The same Turbo engine in a worn condition doesn't have that different of a VE figure.
Interesting that you mentioned "Tuning Tools". A lot more of our customers are getting into additional mods after their initial kit purchases and were looking for a guide to tuning. I may post something on how to use the datalogging and other features of our kits. It's all in a MS-Word doc right now, but I can try to extract the text.
Ok, maybe me using the Honda example was not appropriate because NA vs Turbo cars behave a little differently. The specific-output HP/Ltr of the engine may get lower with wear, but VE doesn't change as much. On an NA engine, flow is initiated by the pistons sucking in air and VE changes as the rings' ability to pull air in changes.
On a Turbo engine, flow is initiated by the turbo pushing air into the engine. Regardless of the wear-rates of the rings or valves, that turbo is going to be cramming in the same amount of air regardless of the condition of the rings and valves. Power is then just a matter of whether the rings and valves can contain that combustion. As a Turbo engine wears, its VE won't change much even though its specfic output will. What does make a big different in VE is changing the actual components such as the diameter, length and shape of the intake-runners, porting & polishing the head, valve-work, etc.
When talking about VE changes, I think we need to refer to different engine configurations, such as different parts. The same Turbo engine in a worn condition doesn't have that different of a VE figure.
Interesting that you mentioned "Tuning Tools". A lot more of our customers are getting into additional mods after their initial kit purchases and were looking for a guide to tuning. I may post something on how to use the datalogging and other features of our kits. It's all in a MS-Word doc right now, but I can try to extract the text.
07-11-2003, 03:27 PM
#37
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I think we addressed the MAF vs MAP long enough. Let's talk about something else for a while.
I'm yet to see 2 cars that are 100% the same. So allowing the user to fine tune things is almost a necessity.
I'll start the new thread..
I'm yet to see 2 cars that are 100% the same. So allowing the user to fine tune things is almost a necessity.
I'll start the new thread..
07-11-2003, 11:06 PM
#39
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Folks ... I have recently diagnosed a faulty AFM in my stock 86 951 ( posted in this forum yesterday). I have priced a new Porsche replacement stock AFM and in Canadian Dollars it comes out to a tad over $700.
I have searched on various Vendors sites of MAF and MAP systems and have narrowed my choices down to two possible vendors. Both sell units at around $950 US ($1300 CDN). When the tax and duties are figured in they come to around $1500 to $1600 Canadian.
My question is, is there a noticable difference in lower end performance that would justify the additional cost? I don't know what stock lower end performance would be as I have been driving the car with a faulty stock AFM (air flow meter) since I got it last year.
Second, if it is justified, is there a vendor or their representative in Canada that could provide the system at a better price? The labour cost is not in the listed price. It seems to be quite easy to install (I build servers, PC's, Cable TV systems, SONT racks, IMCR rated, e.t.c. Second Level Support for the network ... list goes on).
Any help would be greatly appriciated! As a former Technical Trainer and College Instructor, I like to get as much information as possible in coming up with a "more" correct answer/resolution!
Thanks in advance,
Jaak Lepson
<img border="0" alt="[burnout]" title="" src="graemlins/burnout.gif" />
I have searched on various Vendors sites of MAF and MAP systems and have narrowed my choices down to two possible vendors. Both sell units at around $950 US ($1300 CDN). When the tax and duties are figured in they come to around $1500 to $1600 Canadian.
My question is, is there a noticable difference in lower end performance that would justify the additional cost? I don't know what stock lower end performance would be as I have been driving the car with a faulty stock AFM (air flow meter) since I got it last year.
Second, if it is justified, is there a vendor or their representative in Canada that could provide the system at a better price? The labour cost is not in the listed price. It seems to be quite easy to install (I build servers, PC's, Cable TV systems, SONT racks, IMCR rated, e.t.c. Second Level Support for the network ... list goes on).
Any help would be greatly appriciated! As a former Technical Trainer and College Instructor, I like to get as much information as possible in coming up with a "more" correct answer/resolution!
Thanks in advance,
Jaak Lepson
<img border="0" alt="[burnout]" title="" src="graemlins/burnout.gif" />
07-11-2003, 11:16 PM
#40
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Jaak,
If you have the stock turbo, and if you do not plan any performance upgrades in the near future, you might want to find a good used AFM.
I have seen AFM going for around $100 (maybe less). Most people that upgrade to MAF or MAP endup selling the original AFM.
With the stock turbo, there is not much to be gained with the other systems. Which make the
HP/$ not very attractive.
If you have the stock turbo, and if you do not plan any performance upgrades in the near future, you might want to find a good used AFM.
I have seen AFM going for around $100 (maybe less). Most people that upgrade to MAF or MAP endup selling the original AFM.
With the stock turbo, there is not much to be gained with the other systems. Which make the
HP/$ not very attractive.
07-11-2003, 11:50 PM
#41
Rest In Peace Jaak
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fast951 ... since you are a "vendor", would you have a line on a good used one? Or, know someone that is getting rid of theirs? The problem with getting a used one is that I may end up with the same problem again.
I do not plan on updating the turbo other then adding a Lindsay Boost enhancer that I have order this week.
Jaak Lepson
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I do not plan on updating the turbo other then adding a Lindsay Boost enhancer that I have order this week.
Jaak Lepson
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07-12-2003, 12:16 AM
#42
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Jaak,
I'll check around with the guys that have purchased from me. Also, it might be a good idea to post a wanted ad on the classified section.
I'll check around with the guys that have purchased from me. Also, it might be a good idea to post a wanted ad on the classified section.
07-12-2003, 01:03 AM
#43
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I am sure Tim at <a href="http://www.speedforceracing.com" target="_blank">www.speedforceracing.com</a> can get you a good used one for 50 bucks or so. Give him a call.
07-12-2003, 01:08 AM
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Luke:
How can you love the Pro M %^$#*&^??????
This thing is using one (!) **** to adjust the range up to almost 3,000 rpm. Even if you are able to massage in a good A/F ratio with your PC, did you know that your car is running awefully rich at part trottle ???
Give it a kick - into the trash can! Or upgarde to Dannos digital MAF kit.
How can you love the Pro M %^$#*&^??????
This thing is using one (!) **** to adjust the range up to almost 3,000 rpm. Even if you are able to massage in a good A/F ratio with your PC, did you know that your car is running awefully rich at part trottle ???
Give it a kick - into the trash can! Or upgarde to Dannos digital MAF kit.
07-12-2003, 01:17 AM
#45
I'll agree, I think we have beaten this horse to death.
951, I think in all you have a slight but obvious lean towards MAF, as this is what you sell. I think there is nothing wrong in having alot to say about your product. Good for you. But I also feel that your spin is little out of the realm of what really has to be done.
As Guru are now going to offer a MAF kit also says heaps. There must something in them for them to offer this. So to that point, I must tell you that although I feel the way I do, it does not reflect against MAF systems.
I think the real challenge will be when full EFI systems are available to all. That will put both MAF and MAP systems in the backrow.
Then what will we talk about?
951, I think in all you have a slight but obvious lean towards MAF, as this is what you sell. I think there is nothing wrong in having alot to say about your product. Good for you. But I also feel that your spin is little out of the realm of what really has to be done.
As Guru are now going to offer a MAF kit also says heaps. There must something in them for them to offer this. So to that point, I must tell you that although I feel the way I do, it does not reflect against MAF systems.
I think the real challenge will be when full EFI systems are available to all. That will put both MAF and MAP systems in the backrow.
Then what will we talk about?