MyE28.com

[QUOTE="russc"]This evidence actually proves the proper theory, mine. Even with the bad AFM run, look at the 5500 to 6000rpm portion of the dyno run. When the AFM system recovered, the HP/torque curves are very close, maybe a 5 difference. The middle portion of the run shows the benefit of the MAF, but the benefit decreases as the flap opens more, your curve shows that explicitly. The bad AFM run is exactly like Raj's dyno run that is up on TCD's web site as the "M30 respresentative" dyno chart. Well, it's not. As a side point, I think Raj fixed his issue with a AFM swap?, but I can't quite remember, Raj? It could also as stated above, AFM dead spot. That bad run might also be due to adaptation trying to figure out what happened from the differences in the air metering device input!

RussC

[Edit by russc on [TIME]1118947614[/TIME]][/QUOTE]

So you are saying that when the AFM flap is finally open (> 5500 rpm) the AFM performs almost as well as a MAF sensor?

[QUOTE="russc"]This evidence actually proves the proper theory, mine. Even with the bad AFM run, look at the 5500 to 6000rpm portion of the dyno run. When the AFM system recovered, the HP/torque curves are very close, maybe a 5 difference. The middle portion of the run shows the benefit of the MAF, but the benefit decreases as the flap opens more, your curve shows that explicitly. The bad AFM run is exactly like Raj's dyno run that is up on TCD's web site as the "M30 respresentative" dyno chart. Well, it's not. As a side point, I think Raj fixed his issue with a AFM swap?, but I can't quite remember, Raj? It could also as stated above, AFM dead spot. That bad run might also be due to adaptation trying to figure out what happened from the differences in the air metering device input!

RussC

[Edit by russc on [TIME]1118947614[/TIME]][/QUOTE]

[QUOTE="wjones"]So you are saying that when the AFM flap is finally open (> 5500 rpm) the AFM performs almost as well as a MAF sensor?
[/QUOTE]

wow, this thread went to 2 pages.

Yes, exactly, the MAF will make a little more power at the upper range(is it worth the $750-$1k), but more in the middle range. Using the 5500rpm mark is valid for Dukes highly modified engine, this rpm will be lower in a stock M30 engine. the gains will vary from engine to engine.

RussC

[QUOTE="russc"]wow, this thread went to 2 pages.

Yes, exactly, the MAF will make a little more power at the upper range(is it worth the $750-$1k), but more in the middle range. Using the 5500rpm mark is valid for Dukes highly modified engine, this rpm will be lower in a stock M30 engine. the gains will vary from engine to engine.

RussC[/QUOTE]

I wanted to be clear that you were saying the AFM is ALMOST as good as the MAF in that last 15% of available RPM. We spend most of our time driving in ranges below 5k rpm where the MAF has the most benefit. Throttle response is another intangible benefit.

Megasquirt and aftermarket ECUs etc are buildable mods. We don't need to ditch them like a CAI or headers when we go turbo. Most of us will never truly be happy unless were pushing 1.5 bar.

I agree with one thing I dont know about ditching the AFM on a stock motor, the gains might not be worth the cost. However for a 10:1 motor or one that will eventually get a turbo I think it should be on the mod list.



[Edit by wjones on [TIME]1118954093[/TIME]]

Right, Id rather go to a MS for a turbo setup, absolutely. I'm not saying MAF are bad, just not as good as some would think.

RussC

[QUOTE="Duke M535Ti"]You can see they the MAF made more power, period. AFM is crap. Look at 5100 rpm, MAF made 30 HP more. And as mentioned, the throttle response was 100% better.

There is your evidence.[/QUOTE]

If you do the math on the recorded peaks, the MAF provides a little under 6% more HP and 8.5% torque. No appreciable difference in where the peaks occur or the curve overall (save the point where the AFM obviously had a fault). That's not a very compelling argument for me.

Say a turbo can take you from stock 180 HP to 300 HP for $4,000. That's about $34 per HP. If the MAF costs $750 and gets you 12 HP, that's $62.50 per HP. Common sense says if something can only add a minimal improvement and it will cost twice as much for each HP it does add, you postpone it until your options are becoming scarce.

I was thinking this afternoon... vs a stock unchipped Motronic, wouldn't you be able to tune the MS system to advance the timing and remap the curves in order to produce more power, a la what a chip does?

So in effect, vs a stock Motronic, the extra tunability of the MS *would* allow you to create more HP. No?

[QUOTE="Azure"]I was thinking this afternoon... vs a stock unchipped Motronic, wouldn't you be able to tune the MS system to advance the timing and remap the curves in order to produce more power, a la what a chip does?

So in effect, vs a stock Motronic, the extra tunability of the MS *would* allow you to create more HP. No?[/QUOTE]

Yes, thats true. But why would you do all that when you can buy a chip? Which shows the 059 DME is tunable, like I've done.

RussC


[Edit by russc on [TIME]1120698512[/TIME]]

FWIW, I have proof somewhere in my garage in the form of flowbench data that the 027 AFM on my '88 535is provides a lovely 4" pressure drop somewhere north of 300CFM.

[QUOTE="Ed"]FWIW, I have proof somewhere in my garage in the form of flowbench data that the 027 AFM on my '88 535is provides a lovely 4" pressure drop somewhere north of 300CFM.[/QUOTE]

300CFM equals how many ponies?

Jeremy

[QUOTE="Jeremy"]300CFM equals how many ponies?

Jeremy[/QUOTE]

The question should be...
4" of drop at 300CFM equals how many ponies? I don't know. Your average 'Stangbanger could probably quote that off the top of his head. I'm calling one now.

[QUOTE="Ed"]FWIW, I have proof somewhere in my garage in the form of flowbench data that the 027 AFM on my '88 535is provides a lovely 4" pressure drop somewhere north of 300CFM.[/QUOTE]

Ahh, 4 inches of what?

[QUOTE="Ed"]FWIW, I have proof somewhere in my garage in the form of flowbench data that the 027 AFM on my '88 535is provides a lovely 4" pressure drop somewhere north of 300CFM.[/QUOTE]

[QUOTE="wjones"]Ahh, 4 inches of what?[/QUOTE]
Duh, everybody knows it's 4" of hot Jello juice -- it's the world standard. %)

OK, it's 4" of water column.

[QUOTE="wjones"]Ahh, 4 inches of what?[/QUOTE]

PB&J.

300cfm is ~229hp using the conversion of 1 cf of air weighs 0.0765 lbs. ~ every 1lb of air per minute = 10hp. It's unclear to me how inches of water effect air flow/minute. I'm guessing inces of water is a pressure measurement? So, how do we relate pressure to flow of air?

Thanks Ed, you gave us the data, but not the whole story :p

RussC

My 'Stangbanger friend could not quote me a reliable HP number but felt confident that 4" of water was an enormous pressure drop across a single intake component. I asked him to wing it so he gave me a wild assed guess of 10 to 20hp. Keep in mind that the pressure drop and HP loss (whatever it is) would only increase as flow increased. Perhaps one of those desktop dyno software packages would be useful for this sort of problem.

FWIW, I got a 10HP increase at the wheels according to my G Tech Pro with my old MAF conversion.

Ed

[QUOTE="Ed"]FWIW, I have proof somewhere in my garage in the form of flowbench data that the 027 AFM on my '88 535is provides a lovely 4" pressure drop somewhere north of 300CFM.[/QUOTE]

[QUOTE="wjones"]Ahh, 4 inches of what?[/QUOTE]

[QUOTE="Shawn D."]Duh, everybody knows it's 4" of hot Jello juice -- it's the world standard. %)

OK, it's 4" of water column.[/QUOTE]

Ok, Shawn... at what temperature? :p

I've heard others use Hg as well. Even so columnated units are on there way out.


[Edit by wjones on [TIME]1120770809[/TIME]]

[QUOTE="Azure"]I was thinking this afternoon... vs a stock unchipped Motronic, wouldn't you be able to tune the MS system to advance the timing and remap the curves in order to produce more power, a la what a chip does?

So in effect, vs a stock Motronic, the extra tunability of the MS *would* allow you to create more HP. No?[/QUOTE]

[QUOTE="russc"]Yes, thats true. But why would you do all that when you can buy a chip? Which shows the 059 DME is tunable, like I've done.

RussC
[Edit by russc on [TIME]1120698512[/TIME]][/QUOTE]

Probably because in the hot FL summer (like now), the driveability of the E28 with stock Motronic sucks.

I love my E28 as much as the next guy, (quite probably more if my cheque book is a guide), but both my E28s so far (535s) run quite poorly once the temps get above 90F... when the car is running closed loop, it's basically useless, rough, erratic, often sinks down to around 300rpm, before spluttering back up to idle speed.... if you floor it, once it goes open loop it doesn't run *as* bad... but it's still nowhere near the smooth M30 performance I'm used to in lower ambient temps.

I'm seriously thinking of going squirt.

[QUOTE="wjones"]I've heard others use Hg as well. Even so columnated units are on there way out.[/QUOTE]
Then the measurement would be in mm. If columnated units are on their way out, what's the replacement?

[QUOTE="wjones"]I've heard others use Hg as well. Even so columnated units are on there way out.[/QUOTE]

[QUOTE="Shawn D."]Then the measurement would be in mm. If columnated units are on their way out, what's the replacement?[/QUOTE]

inHg @ 32 or 60 degress F are also standards.

You already know examples of non-coloumnared units like bar or psi. They are not temperature dependant.

[QUOTE="Ed"]My 'Stangbanger friend could not quote me a reliable HP number but felt confident that 4" of water was an enormous pressure drop across a single intake component. I asked him to wing it so he gave me a wild assed guess of 10 to 20hp. Keep in mind that the pressure drop and HP loss (whatever it is) would only increase as flow increased. Perhaps one of those desktop dyno software packages would be useful for this sort of problem.

FWIW, I got a 10HP increase at the wheels according to my G Tech Pro with my old MAF conversion.

Ed[/QUOTE]

Guys, in looking at some flow bench sites, 4" of water(it is a columnated measurement) is a very small pressure drop. 1psi = 27" of water :~

So 4" across the AFM is .15psi drop. Now we would have to compare that to a MAF at 300cfm to get it's drop at the same pressure. Does anybody have this data.

RussC

Speaking of pressure drops, here is a neat trick if you have a MAF conversion on your M30....at idle pull off the oil fill cap AND dipstick and see what happens....nothing! Try that with an AFM. Chasing pesky crankcase vacuum leaks to improve idle is a thing of the past.

On the cost side, I'm seeing references here to $1K, but there are much cheaper ways to go. For about $300 you can get a PC programmable box from Split Second. Mate that with a boneyard E36 Bosch HFM like I did and you're good to go. No PC? Go for the a la cart 4-knob unit instead and get your other bits elsewhere. Lots less than $1K...

BK

BK wrote:Speaking of pressure drops, here is a neat trick if you have a MAF conversion on your M30....at idle pull off the oil fill cap AND dipstick and see what happens....nothing! Try that with an AFM. Chasing pesky crankcase vacuum leaks to improve idle is a thing of the past.

Um, While this might b true, your system is still running way lean with that stuff pulled. Your not getting the type of repsonce that the AFM gives do to the fact that the air flow curves of the MAF will not vary much at idle air flows when there is a big change in air flow(what a crappy sentence). This is to say that at low air flows, the MAFs characteristic curves is non linear, so large flow changes will cause very small voltage change where the DME is expecting just the opposite, a large voltage change for small air flow changes. I pressume the MAFs electronic conversion is not doing a very accuate conversion at low air flows % While not a bad thing, sometimes its nice to know when the cap or dipstick is not installed or sealing properly.

On the cost side, I'm seeing references here to $1K, but there are much cheaper ways to go. For about $300 you can get a PC programmable box from Split Second. Mate that with a boneyard E36 Bosch HFM like I did and you're good to go. No PC? Go for the a la cart 4-knob unit instead and get your other bits elsewhere. Lots less than $1K...

Um, what system are you using, the SS programmable or some other? And how did you get the system to work initially? Did someone have a map to start with? I guess I'm asking since if I went this route, Id need some serious tuning for the turbo stuff.

Thanks,
RussC

[Edit by russc on [TIME]1120859190[/TIME]]


[Edit by russc on [TIME]1120859246[/TIME]]

BK wrote:Speaking of pressure drops, here is a neat trick if you have a MAF conversion on your M30....at idle pull off the oil fill cap AND dipstick and see what happens....nothing! Try that with an AFM. Chasing pesky crankcase vacuum leaks to improve idle is a thing of the past.

Um, While this might b true, your system is still running way lean with that stuff pulled. Your not getting the type of repsonce that the AFM gives do to the fact that the air flow curves of the MAF will not vary much at idle air flows when there is a big change in air flow(what a crappy sentence). This is to say that at low air flows, the MAFs characteristic curves is non linear, so large flow changes will cause very small voltage change where the DME is expecting just the opposite, a large voltage change for small air flow changes. I pressume the MAFs electronic conversion is not doing a very accuate conversion at low air flows % While not a bad thing, sometimes its nice to know when the cap or dipstick is not installed or sealing properly.

On the cost side, I'm seeing references here to $1K, but there are much cheaper ways to go. For about $300 you can get a PC programmable box from Split Second. Mate that with a boneyard E36 Bosch HFM like I did and you're good to go. No PC? Go for the a la cart 4-knob unit instead and get your other bits elsewhere. Lots less than $1K...

Um, what system are you using, the SS programmable or some other? And how did you get the system to work initially? Did someone have a map to start with? I guess I'm asking since if I went this route, Id need some serious tuning for the turbo stuff.

Thanks,
RussC

[Edit by russc on [TIME]1120859447[/TIME]]

I love my E28 as much as the next guy, (quite probably more if my cheque book is a guide), but both my E28s so far (535s) run quite poorly once the temps get above 90F... when the car is running closed loop, it's basically useless, rough, erratic, often sinks down to around 300rpm, before spluttering back up to idle speed.... if you floor it, once it goes open loop it doesn't run *as* bad... but it's still nowhere near the smooth M30 performance I'm used to in lower ambient temps.

Sorry about jacking the thread.

Glen,

You need to check the coolant temp sensor and the air temp sensor in the AFM and make sure they're both within spec at operating temps. Sounds like you have something going on which is leaning your A/F mixture too much. As the outside airtemp increase you need to lean an engine (the AFM temp sensor handles this input for the ECU) to attempt to maintain power. However the power output will still be lower with high outside airtemps do to air density changes. You are also at a disadvantage living in Florida, high humidity causes density altitude to increase even higher.

I wouldn't be surprised to see density altitudes of 5000 ft in Florida during the summer. You're 5er's engine thinks it's at the same altitude as Denver, Co. Now the guys in Denver have it even worse. On a hot day they might see density altitudes approaching 10,000 ft !!!!

Rich

Say a turbo can take you from stock 180 HP to 300 HP for $4,000. That's about $34 per HP. If the MAF costs $750 and gets you 12 HP, that's $62.50 per HP.

You know that saying - "You will spend 10% of your money getting 90% of the horsepower. But then you'll spend 90% of your money getting the remaining 10% of the horsepower."
Or something along those lines. I will eventually go with a megasquirt setup after I get another car and turn my e28 into my project/fun car. I think it's benefits are very good with a turbocharged vehicle - more so than everyone suspects with N/A cars. I mean shoot - just looking at the device dead on, that little door is so small! It's gotta be choking everything else up!

[QUOTE="russc"]Um, While this might b true, your system is still running way lean with that stuff pulled. Your not getting the type of repsonce that the AFM gives do to the fact that the air flow curves of the MAF will not vary much at idle air flows when there is a big change in air flow(what a crappy sentence). This is to say that at low air flows, the MAFs characteristic curves is non linear, so large flow changes will cause very small voltage change where the DME is expecting just the opposite, a large voltage change for small air flow changes. I pressume the MAFs electronic conversion is not doing a very accuate conversion at low air flows % While not a bad thing, sometimes its nice to know when the cap or dipstick is not installed or sealing properly.

Um, what system are you using, the SS programmable or some other? And how did you get the system to work initially? Did someone have a map to start with? I guess I'm asking since if I went this route, Id need some serious tuning for the turbo stuff.

Thanks,
RussC

[Edit by russc on [TIME]1120859447[/TIME]][/QUOTE]

You're off base on the first topic. The lack of a significant pressure drop across the MAF translates into very little crankcase vacuum at idle and therefore very little unmetered air even with a pulled oil cap. The system is NOT running lean (as verified by my AFR meter).

The programmable SS unit will need some tuning with a wideband, and ideally some logging capability as well. I'm currently using an ARC2A, but I also have a PSC waiting to go in instead, with an M30 base map supplied by the former owner. I'll dial it in with a full suite of Innovate Motorsports gear.

BK

[QUOTE="BK"]You're off base on the first topic. The lack of a significant pressure drop across the MAF translates into very little crankcase vacuum at idle and therefore very little unmetered air even with a pulled oil cap. The system is NOT running lean (as verified by my AFR meter).

The programmable SS unit will need some tuning with a wideband, and ideally some logging capability as well. I'm currently using an ARC2A, but I also have a PSC waiting to go in instead, with an M30 base map supplied by the former owner. I'll dial it in with a full suite of Innovate Motorsports gear.

BK[/QUOTE]

What, theres a significan pressure drop across the AFM as compared to a MAF? If that was true, the performance of the AFM would be so bad it would never have been used. How much of a pressure drop are we talking about? I don't see it. I guess I should go out with my vacum gauge and check? But my educated guess says the pressure drop across the AFM is very small in comparison to a large vacum leak after the TB. I haven't looked for a long time, isn't the crank case and valve area pressurized from the vacum created from after the TB? I guess I should check that also.

RussC