EBC question
01-31-2002, 08:29 PM
#16
Race Director
[quote]the afm is essentially a potentiometer while the maf generates a variable voltage. <hr></blockquote>Uh, a pot. is a variable voltage output. Depends upon what voltage you drive it with.
I'm not familiar with the Modern Performance MAF, but there's roughly two types. One puts out variable-voltage and the other has a frequency output.
I'm not familiar with the Modern Performance MAF, but there's roughly two types. One puts out variable-voltage and the other has a frequency output.
01-31-2002, 09:01 PM
#17
Race Director
All Im really asking is: is it feasible to run APEXi's AFC rather than the ARC2. From what Ive heard the ARC2 is very limited in tuning, but on the other hand the APEXi's might suck even more..I have no idea and was just wondering why no one runs the APEXi version. Is it just because it wont work, or is it because it is not included in any of the MAF packages currently offered?
The modern performace MAF might be a piece of *rap, I just know one person on the list bought one, which I dont even think has been installed yet..so who knows.
Just keeping my options open...
Thanks for all the answers though!
The modern performace MAF might be a piece of *rap, I just know one person on the list bought one, which I dont even think has been installed yet..so who knows.
Just keeping my options open...
Thanks for all the answers though!
01-31-2002, 11:02 PM
#18
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[quote]Originally posted by Danno:
<strong>Uh, a pot. is a variable voltage output. Depends upon what voltage you drive it with.</strong><hr></blockquote>
I know that, but just didn't pose my question correctly. The afm in our cars outputs a 0-5v (closed to open) signal. Is this signal linear to air flow? (I don't know) The maf sensors (most of them) also output a 0-5v signal (no flow to high flow I believe) that is not linear from what I have read. The super afc can adjust the input signal (V) from the flow sensor by + or - 50% in 500 rpm increments and output this modified signal to the computer. If this is enough of a change, then I would think the s-afc can perform the same function as an arc2 in a maf conversion (probably better). Is this enough of a change? This is what I meant, because I've never heard of a s-afc being used for a maf conversion.
Rob
<strong>Uh, a pot. is a variable voltage output. Depends upon what voltage you drive it with.</strong><hr></blockquote>
I know that, but just didn't pose my question correctly. The afm in our cars outputs a 0-5v (closed to open) signal. Is this signal linear to air flow? (I don't know) The maf sensors (most of them) also output a 0-5v signal (no flow to high flow I believe) that is not linear from what I have read. The super afc can adjust the input signal (V) from the flow sensor by + or - 50% in 500 rpm increments and output this modified signal to the computer. If this is enough of a change, then I would think the s-afc can perform the same function as an arc2 in a maf conversion (probably better). Is this enough of a change? This is what I meant, because I've never heard of a s-afc being used for a maf conversion.
Rob
03-17-2002, 03:33 AM
#19
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[quote]Originally posted by Danno:
<strong>Adjustable boost is a pretty big mis-understanding. For any and every boost-level, there is but one optimal fuel and ignition curve. It's hard enough to control one variable (boost) so that you can dial in fuel & spark to optimize power at that boost level. Really only way to optimize this is with custom chips and dyno tuning (or using a complete replacement EFI systen like SDS, TEC-II/III, Motec, etc).
When you finally have fuel & spark dialed in optimially, any other boost level is a compromise; you aren't making maximum power possible, unless you have aftermarket EFI that can alter fuel&spark to match new boost level.
Actually, if you have things dialed in to say.... 15psi of boost, you can't even run higher boost like 18psi, because your fuel will be too lean and spark too advanced; you'll get knock for sure. However, if you set your car up for 18psi of boost, you aren't making optimal power at 15psi either. It'll be too rich with ignition too retarded.
So don't bother with adjustable boost. Set it to the maximum you can safely use and tune your fuel & spark for that boost level. Then just use the accelerator pedal to adjust how much power you want to lay down. If you're just trolling around town and want to take stress off yor engine, just don't give it as much throttle.</strong><hr></blockquote>
Danno, doesn't the AFM sense more air with a ebc and then catch up the fuel to match? don't our cars have sensors to sense the amount of air and compensate fuel and spark? if not, then wouldn't a APEXi SAFC work to do this? (I've found a great deal on both the SAFC ($295 new) and the AVC-R ($399-$430).
I just thought that if you dial in more boost, the computer/sensors will detect and adjust to line up to the fuel/spark curve that is burnt on the current chips in the car.
<strong>Adjustable boost is a pretty big mis-understanding. For any and every boost-level, there is but one optimal fuel and ignition curve. It's hard enough to control one variable (boost) so that you can dial in fuel & spark to optimize power at that boost level. Really only way to optimize this is with custom chips and dyno tuning (or using a complete replacement EFI systen like SDS, TEC-II/III, Motec, etc).
When you finally have fuel & spark dialed in optimially, any other boost level is a compromise; you aren't making maximum power possible, unless you have aftermarket EFI that can alter fuel&spark to match new boost level.
Actually, if you have things dialed in to say.... 15psi of boost, you can't even run higher boost like 18psi, because your fuel will be too lean and spark too advanced; you'll get knock for sure. However, if you set your car up for 18psi of boost, you aren't making optimal power at 15psi either. It'll be too rich with ignition too retarded.
So don't bother with adjustable boost. Set it to the maximum you can safely use and tune your fuel & spark for that boost level. Then just use the accelerator pedal to adjust how much power you want to lay down. If you're just trolling around town and want to take stress off yor engine, just don't give it as much throttle.</strong><hr></blockquote>
Danno, doesn't the AFM sense more air with a ebc and then catch up the fuel to match? don't our cars have sensors to sense the amount of air and compensate fuel and spark? if not, then wouldn't a APEXi SAFC work to do this? (I've found a great deal on both the SAFC ($295 new) and the AVC-R ($399-$430).
I just thought that if you dial in more boost, the computer/sensors will detect and adjust to line up to the fuel/spark curve that is burnt on the current chips in the car.
03-17-2002, 07:29 AM
#20
Race Director
Well, the DME/KLR combo isn't that smart. At full-throttle at high-RPM, it drops into open-loop mode and ignores a lot of sensor inputs and uses built-in tables for injector duty-cycle vs RPM. If you haven't noticed, going from 15psi with optimal fuel & spark leads to a lean condition with too much ignition advance at 18psi. Then you have to get out and adjust fuel-pressure to compensate. Depending upon the MAF sensor and turbo you have, there may even be signal clipping as well (sensor outputs 5v max flow from 5000-7000rpm).
The S-AFC is a great unit. It allows you to custom tailor a fuel-curve with much, much higher resolution than the ARC2. You can do things like dial back idle mixture by 25%, decrease mid-range fuel by 10% and add 10% to the top-end; something that's tough to do with the ARC2.
The S-AFC is a great unit. It allows you to custom tailor a fuel-curve with much, much higher resolution than the ARC2. You can do things like dial back idle mixture by 25%, decrease mid-range fuel by 10% and add 10% to the top-end; something that's tough to do with the ARC2.
03-18-2002, 01:36 AM
#21
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I read that the apexi unit has resolutions of 500 rpm.. that sound pretty good and all, but what happens betweent those rpms?
if i change 2500 and 3000rpm levels, what goes on between 2600 and 2900? just like a stereo graphic equalizer, you can only adjust the preset frequencies and nothing in between.. a better choice is a parametric eq that actually adjusts all surrounding frequencies as well to make a smoother curve rather than a stair-step type curve.. does the apexi do anything similar to this? or would I end up with a jumpy curve??
if i change 2500 and 3000rpm levels, what goes on between 2600 and 2900? just like a stereo graphic equalizer, you can only adjust the preset frequencies and nothing in between.. a better choice is a parametric eq that actually adjusts all surrounding frequencies as well to make a smoother curve rather than a stair-step type curve.. does the apexi do anything similar to this? or would I end up with a jumpy curve??
03-18-2002, 03:43 PM
#22
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Im curious, Im using a HKS EVC4 on my 951. Will the SAFC work with it? Also, another thing that I feel is trying to be said here; if someone was to buy the Pro Flow MAF kit for the 675.,then get rid of the basic a/f controller that it comes with and use the SAFC from apexi, wouldnt this be a great setup for a lower price then the other MAF on the market (1500.00), and be more efficient? Im very curious about the Pro Flow kit because of the price, but understand that it is lacking a A/F controller that gives adjustablity across the RPM spectrum.
03-18-2002, 04:14 PM
#23
Nordschleife Master
[quote]Originally posted by SamGrant951:
<strong>
The modern performace MAF might be a piece of *rap, I just know one person on the list bought one, </strong><hr></blockquote>
The Autothority kit is a PRO FLOW. The Autothority is by no means *rap. Maybe next week I'll have #'s. I have to break in my rod bearings too.
<strong>
The modern performace MAF might be a piece of *rap, I just know one person on the list bought one, </strong><hr></blockquote>
The Autothority kit is a PRO FLOW. The Autothority is by no means *rap. Maybe next week I'll have #'s. I have to break in my rod bearings too.
03-18-2002, 07:12 PM
#24
From my limited research on the Apexi AFC - my understanding is that Apexi AFC is not used on load based or turbo cars because it controls the fuel curve based on rpm and not load.
I investigated this before purchasing the ARC 2. In the end I was reluctant to purchase the Apexi due to the fact that no one seemed to be using this inconjucntion with a MAF on a 951.
I investigated this before purchasing the ARC 2. In the end I was reluctant to purchase the Apexi due to the fact that no one seemed to be using this inconjucntion with a MAF on a 951.
03-18-2002, 08:29 PM
#25
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dlr944,
Your right, I have not seen it used in combination with a MAF kit, but I have read a Porsche magazine from England about a year ago where they compared a new 996tt against a 951 modified by a company called DP Motorsports. All they did to their customer's 915 is integrate APEX-I EBC and A/F controller to the stock engine. With that and a changed head gasket they were producing 350hp/350lbstq. So I know that you can use the APEX-I A/F unit, but I do not know what effect it would have using with a MAF kit. Their are people doing this currently though. <img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />
Your right, I have not seen it used in combination with a MAF kit, but I have read a Porsche magazine from England about a year ago where they compared a new 996tt against a 951 modified by a company called DP Motorsports. All they did to their customer's 915 is integrate APEX-I EBC and A/F controller to the stock engine. With that and a changed head gasket they were producing 350hp/350lbstq. So I know that you can use the APEX-I A/F unit, but I do not know what effect it would have using with a MAF kit. Their are people doing this currently though. <img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />
03-20-2002, 03:06 AM
#27
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I'm pretty sure that there have been a few threads on the aftermarket a/f controllers before.
There are 2 basic problems. The first is trying to work out the damn wiring <img src="graemlins/cussing.gif" border="0" alt="[grrrrrrr]" /> , but the second is that you also need to get a analogue/digital converter. The MAF pumps out an analogue signal for our 12 year old computers, whereas the HKS AFR (and I expect the Apex-i) use a digital signal. I've heard also that the voltage of the output on the MAF can make a difference, but I'm still checking that out!
There are 2 basic problems. The first is trying to work out the damn wiring <img src="graemlins/cussing.gif" border="0" alt="[grrrrrrr]" /> , but the second is that you also need to get a analogue/digital converter. The MAF pumps out an analogue signal for our 12 year old computers, whereas the HKS AFR (and I expect the Apex-i) use a digital signal. I've heard also that the voltage of the output on the MAF can make a difference, but I'm still checking that out!
03-20-2002, 03:22 AM
#28
Race Director
Hmm, I don't think there's any MAF sensors out there for any cars that output a digital signals for import rice or European cars. GM has frequency-output MAF sensors, not sure if you can call that digital either.
Actually pretty much ALL the piggy-back add-on signal massagers work my intercepting the analog airflow signal before it gets to the computer, modifying it to fool the computer and sending it on. All the analog-to-digital conversion is done with the tranducers inside the computers themselves.
As for the load vs. RPM tuning of the airflow signal, that's irrelevant. I remember the exact thread several years ago where this info was posted. It was primarily a way for a certain vendor to protect his (at the time) monopolistic market share since he didn't carry anything but the ARC2 unit.
I say it's irrelevant because the only time you're really massaging the airflow signal to fine-tune fuel metering is at full-throttle/full-load at high-RPM anyway. Under all other conditions like idle and mid-range/partial throttle, the computer is in close-loop feedback with the O2-sensor anyway. So the air-fuel ratio is maintained at an average 14.7:1 automatically.
It's only under open-loop full-throttle/load high-RPM conditions when the pre-programmed maps in the chips don't match the actual airflow conditions that we need to resort to using piggyback signal-massagers like the ARC2 and S-AFC. And any of you who've tried to get rid of the mid-range richness, high-RPM lean conditions that exist on our cars with upgraded turbos and MAF kits knows, the ARC2 is far from a precise solution. Would you believe that with a S-AFC unit, you can dial in the proper fuel-curve in less than 30-minutes with only two dyno runs?
Actually pretty much ALL the piggy-back add-on signal massagers work my intercepting the analog airflow signal before it gets to the computer, modifying it to fool the computer and sending it on. All the analog-to-digital conversion is done with the tranducers inside the computers themselves.
As for the load vs. RPM tuning of the airflow signal, that's irrelevant. I remember the exact thread several years ago where this info was posted. It was primarily a way for a certain vendor to protect his (at the time) monopolistic market share since he didn't carry anything but the ARC2 unit.
I say it's irrelevant because the only time you're really massaging the airflow signal to fine-tune fuel metering is at full-throttle/full-load at high-RPM anyway. Under all other conditions like idle and mid-range/partial throttle, the computer is in close-loop feedback with the O2-sensor anyway. So the air-fuel ratio is maintained at an average 14.7:1 automatically.
It's only under open-loop full-throttle/load high-RPM conditions when the pre-programmed maps in the chips don't match the actual airflow conditions that we need to resort to using piggyback signal-massagers like the ARC2 and S-AFC. And any of you who've tried to get rid of the mid-range richness, high-RPM lean conditions that exist on our cars with upgraded turbos and MAF kits knows, the ARC2 is far from a precise solution. Would you believe that with a S-AFC unit, you can dial in the proper fuel-curve in less than 30-minutes with only two dyno runs?
03-20-2002, 05:14 PM
#29
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Hey Danno,
As usual, words from the wise
.......
I know that lots of Euro car manufacturers are now using digital air signal devices to control stuff. Mostly down to those pesky Californians
and their emissions!
Anyway, After reading the instructions for the HKS unit I've got, it does state that you need the optional D/A converter for the computer to be used on certain vehicles! I know, I know... could be just a sales thing, but hey, I'm sure they know their own unit, Plus it's 'only' $50!!
From what you've written, it sounds as though you have some experience of these units... do tell
Easter's gonna be a busy holiday for me!! timing belt and pulleys to do (spotted a dodgy bearing on an idler pulley
), plus the headlight job, and now I'm in the mood to have another look at this thing! All and any starting points and advice greatly appreciated <img src="graemlins/bigok.gif" border="0" alt="[thumbsup]" />
As usual, words from the wise
.......I know that lots of Euro car manufacturers are now using digital air signal devices to control stuff. Mostly down to those pesky Californians
and their emissions!Anyway, After reading the instructions for the HKS unit I've got, it does state that you need the optional D/A converter for the computer to be used on certain vehicles! I know, I know... could be just a sales thing, but hey, I'm sure they know their own unit, Plus it's 'only' $50!!
From what you've written, it sounds as though you have some experience of these units... do tell
Easter's gonna be a busy holiday for me!! timing belt and pulleys to do (spotted a dodgy bearing on an idler pulley
), plus the headlight job, and now I'm in the mood to have another look at this thing! All and any starting points and advice greatly appreciated <img src="graemlins/bigok.gif" border="0" alt="[thumbsup]" />
03-21-2002, 02:08 AM
#30
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Danno, move slowly away from your brain...very slowly...keeps your hands out where I can see them...its for the better, your gonna expload yourself. I'm here to help...
Man, If I knew you were this damn "up on the subject" I would have offered you a job...quit it!!!! YOur making my head hurt....I'm still trying to digest your posts from a month ago! I thought I was a tuner...your putting me to shame man! Your punishment for this torture of yours....you have to buy me a pizza with the toppings of my choice...no arguments...just do it!
Man, If I knew you were this damn "up on the subject" I would have offered you a job...quit it!!!! YOur making my head hurt....I'm still trying to digest your posts from a month ago! I thought I was a tuner...your putting me to shame man! Your punishment for this torture of yours....you have to buy me a pizza with the toppings of my choice...no arguments...just do it!