wide band afr data coming soon...

[mbtoloczko]

I finally got my wide band O2 sensor and meter installed last night. The system is made by Innovate Motorsports (http://www.innovatemotorsports.com/). I've got bungs welded into both primary pipes, so I can log either bank of cylinders. The meter can log up to 45 minutes of data which I can download to a computer and plot. I also bought the optional analog input cable, so in addition to logging afr, I'll be logging engine rpm, TPS voltage, MAF voltage, knock sensor #1, and knock sensor #2. I haven't got the analog input cable installed yet though. Need to get some mil spec wire taps. I was hoping to get some afr data this morning, but I had to head into work. I'll have data this evening.

Sensor location:
http://www.subaru-svx.net/photos/files/mbtoloczko/26075.jpg


LM-1 meter and data logger:
http://www.subaru-svx.net/photos/files/mbtoloczko/26076.jpg

[Chiketkd]

That's awesome Mychailo. Glad you have it up and running. I look forward to seeing your results this evening!

-Chike

[SVXtasy]

So why not just replace you stock o2 sensors with the wideband’s? I have been looking in to buying 2 of the Lc-1 form innovative but I have run in to information that says not to mount WB o2 so close the port. I like your setup. I very well may be running something like that soon :) my WB readings form my PLX M-300 are very helpful for tuning my turbo setup.

[mbtoloczko]

A WB O2 sensor produces a different voltage response than a narrowband O2 sensor. The LM-1 meter can take the WB O2 signal and output an NB O2 signal, but then I'd have to snip my SVX wiring harness and send the signal from the LM-1 into the ECU. So, I guess it just seems easier to keep the NB and WB duties separated.

Where do you have your OEM O2 sensors located?

[SVXtasy]

Right after the turbo

[mbtoloczko]

Less than 12" from the turbo?

[SVXRide]

Mychailo,
Very nice! I've been looking at Innovate's system, just haven't been able to justify the $350-450 price :eek: Are you using Bosch 5 wire O2 sensors? I'll PM you with some thoughts....
-Bill

[mbtoloczko]

Not sure what sensor it is. Could be 5-wire. The plug has six pins. I rationalized away the cost long ago. :-)

[Phast SVX]

99% of the 02s out there use the 5 wire bosch that wears out rather fast if you just leave it in.
phil

[SVXRide]

Checked the Innovate web site. Their system uses the
Bosch LSU4.2 5-wire, wide-band O2 sensor.
-Bill

[drivemusicnow]

For my eclipse I'm buying a zeitronix wideband kit... Its a pretty quality kit. I'm getting it with the boost sensor and egt gauge also. All of it is loggable. check it out here: www.zeitronix.com

Also, you want to keep a wideband sensor at LEAST 18 inches away from the manifold.

[SVXtasy]

Yes Less then 12" Why?


Less than 12" from the turbo?

[mbtoloczko]

Yes Less then 12" Why?

At first I was thinking that the exhaust gases might be too hot at less than 12" from the turbo, but after thinking about it, I doubt it. In the NA config, they are 24" from the exhaust port.

[SVXtasy]

Well my turbo is quite some distance form the exhaust port so I don’t think that heat will be a problem. But I would like to put two of the LC-1's in the stock locations. What is the problem heat? Or flow? I have heard both. If I keep my EGT's below 850c then the sensor should not have any problems right? Don’t the sensors work at everything below 850c EGT? Thanks

[mbtoloczko]

For my eclipse I'm buying a zeitronix wideband kit... Its a pretty quality kit. I'm getting it with the boost sensor and egt gauge also. All of it is loggable. check it out here: www.zeitronix.com

...

That one looks pretty nice too. I like the fact that it has a compact controller, a remote readout, and it shows afr and egt together.

[mbtoloczko]

Well my turbo is quite some distance form the exhaust port so I don’t think that heat will be a problem. But I would like to put two of the LC-1's in the stock locations. What is the problem heat? Or flow? I have heard both. If I keep my EGT's below 850c then the sensor should not have any problems right? Don’t the sensors work at everything below 850c EGT? Thanks

I wouldn't think its a flow problem. I think heat is the usual problem. But if you are behind the turbo, I think you're fine. The drop in exhaust pressure across the turbo will have a cooling effect on the exhaust gas.

[mbtoloczko]

Finally did some AFR runs. I don't have rpm, TPS, or MAF datalogging enabled yet. Here's the mods I've done to my car:

1) I'm running an Impreza 2.5 RS fuel pressure regulator in my car which should richen the AFR by one point in open-loop mode (greater than 25% throttle).
2) The car has a custom exhaust.
3) I'm running aftermarket sparkplugs.
4) I've got a very mild ram-air system installed.
Otherwise, the motor is stock.

My first general observation is that when the engine is operating in closed-loop mode (light throttle), the afr is right on stoich. I'm surprised the SVX doesn't get better gas mileage.

My second general observation is that at aggressive throttle positions where the engine is operating in open-loop mode, the afr is super rich with the Impreza 2.5RS fpr. Its in the range of 12.5:1 to 11.5:1. No wonder the exhaust tips on my car are covered in soot!

Anyhow, I did four runs, with each run a little different. Some of the plots are shown below. In every case, once the ecu goes open-loop, the afr quickly richens to 12.5:1, and then gets even richer as the engine goes past 5000 rpm.

So, the next step is the throw the OEM SVX fpr back on the car and do another set of runs. Glad I kept it. This should put the afr in the range of 13.5-12.5:1, but its probably not the best solution either. Below 5000 rpm, the afr will be a little to lean for max power, and then beyond 5000 rpm, it will be right on the money for max power. The best solution would probably be to install an SAFC-II so that the afr could tuned to 13:1 across the entire rpm range.

It would be very interesting to see what afr values would be obtained on a completely stock car.

Run #3 (afr vs time): 3rd gear, WOT, uphill
http://www.subaru-svx.net/photos/files/mbtoloczko/26183.gif


Run #3 (afr vs rpm): 3rd gear, WOT, uphill
http://www.subaru-svx.net/photos/files/mbtoloczko/26184.gif


Run #2 (afr vs time): 4th gear, WOT, slight incline
http://www.subaru-svx.net/photos/files/mbtoloczko/26182.gif


Run #4 (afr vs time): 3rd gear, about 1/2 throttle, slight incline
http://www.subaru-svx.net/photos/files/mbtoloczko/26185.gif

[SVXRide]

Mychailo,
Nice! Are you going to try to do some runs with your Mr. Dyno running in parallel?
-Bill

[Chiketkd]

Interesting results Mychailo. I guess that graph explains a lot of my findings with the Impreza fpr as well. However, based on my dyno runs with the stock fpr last December, the richest the afr ever got was ~13.4:1-13.3:1 at WOT above 5000rpms.

It's interesting that the afr centers around 12.5:1 and then becomes even richer in the upper rpms! Per an article in SubieSport Magazine a few months back (when Huck369 was first featured), an afr of 11.6:1 or richer is needed to safely run an extra 5* of timing advance... :D Maybe I know what my next mod will be! :)

-Chike

P.S. I was doing some calculations the other day and realized just how much more fuel our engines would get in open loop by raising the fuel pressure by ~7psi.

Our injectors flow 275cc/min at a fuel pressure of 36.3psi
If the max fuel pressure is raised to 43.5 psi, then our injectors will effectively be able to flow: 329.5cc/min

Moreover, if people have estimated that 275cc/min can support 250hp on the motor, then 329.5cc/min should be able to support 295hp (assuming a linear relationship).

[Phast SVX]

Interesting results Mychailo. I guess that graph explains a lot of my findings with the Impreza fpr as well. However, based on my dyno runs with the stock fpr last December, the richest the afr ever got was ~13.4:1-13.3:1 at WOT above 5000rpms.

It's interesting that the afr centers around 12.5:1 and then becomes even richer in the upper rpms! Per an article in SubieSport Magazine a few months back (when Huck369 was first featured), an afr of 11.6:1 or richer is needed to safely run an extra 5* of timing advance... :D Maybe I know what my next mod will be! :)

-Chike

P.S. I was doing some calculations the other day and realized just how much more fuel our engines would get in open loop by raising the fuel pressure by ~7psi.

Our injectors flow 275cc/min at a fuel pressure of 36.3psi
If the max fuel pressure is raised to 43.5 psi, then our injectors will effectively be able to flow: 329.5cc/min

Moreover, if people have estimated that 275cc/min can support 250hp on the motor, then 329.5cc/min should be able to support 295hp (assuming a linear relationship).


hence why, with the bumped up fp on my dry shot, i can run the 80 shot no problem(easliy 7lbs more of fp)
phil

[Chiketkd]

hence why, with the bumped up fp on my dry shot, i can run the 80 shot no problem(easliy 7lbs more of fp)
phil
Good point. An Impreza fpr definitely has it +ves in an SVX!

I definitely plan to keep the '01 Impreza fpr in my car. In closed loop, the afr stays around stoich so my gas mileage won't suffer, but in open loop, it'll be able to support some extra hp down the road (performance cams, etc.) ;)

-Chike

[mbtoloczko]

Interesting results Mychailo. I guess that graph explains a lot of my findings with the Impreza fpr as well. However, based on my dyno runs with the stock fpr last December, the richest the afr ever got was ~13.4:1-13.3:1 at WOT above 5000rpms.

It's interesting that the afr centers around 12.5:1 and then becomes even richer in the upper rpms! Per an article in SubieSport Magazine a few months back (when Huck369 was first featured), an afr of 11.6:1 or richer is needed to safely run an extra 5* of timing advance... :D Maybe I know what my next mod will be! :)

-Chike

P.S. I was doing some calculations the other day and realized just how much more fuel our engines would get in open loop by raising the fuel pressure by ~7psi.

Our injectors flow 275cc/min at a fuel pressure of 36.3psi
If the max fuel pressure is raised to 43.5 psi, then our injectors will effectively be able to flow: 329.5cc/min

Moreover, if people have estimated that 275cc/min can support 250hp on the motor, then 329.5cc/min should be able to support 295hp (assuming a linear relationship).

Hi Chike,

When you did the dyno runs in your car, I would guess that the shop simply put a wide-band O2 sensor in the tailpipe of your car. If that's the case, the afr reading is not going to be terribly accurate because its taking a reading of the exhaust after it goes through catalytic converters. From what I've read, dyno systems add a generic correction factor to the afr reading to attempt to compensate for the exhaust gas composition being altered by the cats. Bottom line is that the afr readings from your dyno runs are only approximate.

Be careful about running too rich. Running too rich can also cause detonation. 11.6:1 is probably not the optimum afr for timing advance.

I have not been able to understand why, but fuel flow from a fuel injector is not linearly proportional to the fuel pressure. Its proportional to the square root of the fuel pressure. I've talked with RCEng about it several times. Its what they see when they measure the flow rate of injectors. So going from 36.3 psi to 43.5 psi will only raise the max fuel flow by 9.5%.

I'd like to throw the SVX fpr back in the car, but I don't think I'm going to have time for about a month.

[svxfiles]

Mychailo, do you think phenolic spacers would lean the mixture due to lower intake manifold temps?

And what were the ambiant temps?

:cool: I want one too.

[SVXRide]

Mychailo,
Parts ordered from Innovate! Exhaust mods are scheduled for the 25th of this month, so I'll be ready for road tests by the end of the month!
-Bill

[longassname]

Actually the stock injectors only flow 270cc at 3 bar. There is unfortunately no getting around it; the fuel injectors are tiny. The amount of fuel increase to go from the afr you want to dirty rich isn't really very much in comparison to to the amount of fuel increase to get more hp. I'll let you guys play with that math yourself. I think you'll find it interesting.

As for the afr on a completely stock svx you can see them now on the ECUtune website. At the upper rpms an afr anywhere between what we have on stage 1 and factory will do well, any richer and you will loose power--at least in the case of a stock svx. When we developed stage 1 on the dyno we didn't have the v4 ignition timing revision map alterations in place yet. It's possible that with this ability to further advance the ignition timing that even a little richer afr would be beneficial.

It's cool you guys are getting out there and measuring this stuff for yourself. It's nice to see some performance oriented svx'ers out there.




Interesting results Mychailo. I guess that graph explains a lot of my findings with the Impreza fpr as well. However, based on my dyno runs with the stock fpr last December, the richest the afr ever got was ~13.4:1-13.3:1 at WOT above 5000rpms.

It's interesting that the afr centers around 12.5:1 and then becomes even richer in the upper rpms! Per an article in SubieSport Magazine a few months back (when Huck369 was first featured), an afr of 11.6:1 or richer is needed to safely run an extra 5* of timing advance... :D Maybe I know what my next mod will be! :)

-Chike

P.S. I was doing some calculations the other day and realized just how much more fuel our engines would get in open loop by raising the fuel pressure by ~7psi.

Our injectors flow 275cc/min at a fuel pressure of 36.3psi
If the max fuel pressure is raised to 43.5 psi, then our injectors will effectively be able to flow: 329.5cc/min

Moreover, if people have estimated that 275cc/min can support 250hp on the motor, then 329.5cc/min should be able to support 295hp (assuming a linear relationship).

[mbtoloczko]

Mychailo,
Parts ordered from Innovate! Exhaust mods are scheduled for the 25th of this month, so I'll be ready for road tests by the end of the month!
-Bill

PM me with your home address.

[Chiketkd]

Hi Chike,

When you did the dyno runs in your car, I would guess that the shop simply put a wide-band O2 sensor in the tailpipe of your car. If that's the case, the afr reading is not going to be terribly accurate because its taking a reading of the exhaust after it goes through catalytic converters. From what I've read, dyno systems add a generic correction factor to the afr reading to attempt to compensate for the exhaust gas composition being altered by the cats. Bottom line is that the afr readings from your dyno runs are only approximate.

Be careful about running too rich. Running too rich can also cause detonation. 11.6:1 is probably not the optimum afr for timing advance.

I have not been able to understand why, but fuel flow from a fuel injector is not linearly proportional to the fuel pressure. Its proportional to the square root of the fuel pressure. I've talked with RCEng about it several times. Its what they see when they measure the flow rate of injectors. So going from 36.3 psi to 43.5 psi will only raise the max fuel flow by 9.5%.

I'd like to throw the SVX fpr back in the car, but I don't think I'm going to have time for about a month.
Mychailo,

You are right that the dyno shop only measured my afr from the tail pipe. As a result, I'd be very interested in learning whether the stock SVX ECU actually richens the afr to somewhere in the 12:1-13:1 range in open loop operation. That'd be pretty optimum for a factory fuel system! :cool:

I came across the following graph today showing the pressure created by burning gas at different afr's taken from 'The Sports Car Engine: Its Tuning and Modification' by Colin Campbell:

http://ackthud.com/shawnfogg/pics/supercharger/mixture-loop.jpg

http://www.ackthud.net/shawnfogg/mixture.htm

It is noted on the above site that: "Maximum power is usually obtained running around a 12.3:1 AFR. Going richer then that will cost a little power but you loose less power then being leaner then 12.3:1"

Depending on your wideband results with the SVX fpr, I may switch back to one. I just don't understand why the afr was first richened to 12.5:1 in open loop and then went all the way to 11.4:1 above 5000rpms???? (I was expecting it to actually lean out slightly in the upper rpms)

My dyno plot at Altered Atmosphere on 12-15-04 showed the slightest richening in the afr's above 5000rpms, but nothing to the degree that you measured...

http://www.subaru-svx.net/photos/files/Chiketkd/23161.jpg

My thoghts:

If the max fuel flow was truly only increased by 9.5% by raising the fuel pressure to 43.5psi, then an afr of around 12.5:1 in open loop would be the expected result. The increase to 11.5:1 makes me think that something else may be at play...

- Is the vacuum line that goes to your Impreza fpr properly hooked up and in good condition? (any small cracks in the rubber???)

- You mentioned you have aftermarket spark plugs. Are they running a colder or hotter spark compared to the stock NGK's? I know certain types of plugs work better in richer or leaner afr's. Is it possible that your aftermarket plugs might not be the best suited for running in a rich afr mixture?

Just my $0.02...

-Chike

[deruvian]

All this richening of afr at high RPMs says to me that the SVX could really benefit from some variable valve timing. Rather, to generalize this statement, increase the air at high RPMs and you may be able to lean out the mixture just enough to gain some power.

[Chiketkd]

Two other thoughts Mychailo:

- Have you modified your fuel pump or voltage to your fuel pump in any way?

- How have you set up your ram air? Is it possible that your engine may be starved of air above 5,000rpms?

Just tossing around some ideas...

-Chike

[mbtoloczko]

Chike,

I have that same fuel consumption vs cylinder pressure plot in my locker. :-) As far as I know, the 2.5 RS fpr is working fine. I haven't looked at the vacuum line though. I haven't touched the fuel pump in any way. I suppose its possible that the ram air is having some effect, but keep in mind that the ecu does not just blindly add fuel. It meters fuel based on the MAF sensor reading (among other readings), so if the ram air is somehow messing up airflow at high rpm, the MAF would see this, and the ecu would add less fuel accordingly.

I'm fairly convinced that the afr reading is representative of what the SVX ecu is programmed to do. The other EG33 afr readouts from dyno runs that I've seen (SVXRide, LAN) show the afr progressively richening as the rpms increase. And if I look at the afr readings from your dyno runs, I see the same basic trend too. The afr on your car does richen as the rpms increase, and at peak rpm, there is a slight lean out. My afr runs show the same thing, and so do LANs.

As deruvian said, a little more power may be possible with the 2.5RS fpr by leaning out the mixture a bit at higher rpm using an SAFC-II (or something like it).

[mbtoloczko]

Mychailo, do you think phenolic spacers would lean the mixture due to lower intake manifold temps?

And what were the ambiant temps?

:cool: I want one too.

The phenolic spacers shouldn't affect the afr. No matter how hot or cool the air gets after the MAF, the MAF is still correctly measuring the amount of air that's going into the motor.

Outside air temp was around 55-60F.

[Chiketkd]

Chike,

I have that same fuel consumption vs cylinder pressure plot in my locker. :-) As far as I know, the 2.5 RS fpr is working fine. I haven't looked at the vacuum line though. I haven't touched the fuel pump in any way. I suppose its possible that the ram air is having some effect, but keep in mind that the ecu does not just blindly add fuel. It meters fuel based on the MAF sensor reading (among other readings), so if the ram air is somehow messing up airflow at high rpm, the MAF would see this, and the ecu would add less fuel accordingly.

I'm fairly convinced that the afr reading is representative of what the SVX ecu is programmed to do. The other EG33 afr readouts from dyno runs that I've seen (SVXRide, LAN) show the afr progressively richening as the rpms increase. And if I look at the afr readings from your dyno runs, I see the same basic trend too. The afr on your car does richen as the rpms increase, and at peak rpm, there is a slight lean out. My afr runs show the same thing, and so do LANs.

As deruvian said, a little more power may be possible with the 2.5RS fpr by leaning out the mixture a bit at higher rpm using an SAFC-II (or something like it).
Mychailo,

While the SVX ECU richens the afr to a degree in the upper rpms, the increase you got above 5000 rpms was much larger than I expected. I guess I'll have to see your runs with the SVX fpr before any definite conclusions can be drawn...

I must say, I've always been wary of non-factory ram-air systems - and I still wonder if your system might not have supplied enough air to the engine above 5,000rpms (which in turn would have richened the afr). As you did your runs in 3rd gear in a 5spd car, you must have been going 90+mph as you approached redline. At these speeds, the air flow over your car would have caused more 'pronounced' regions of low and high pressure to form - and if your ram-air was placed in a non-ideal location (e.g. hole at bottom of the inner fender per Terry's SVX FAQ), air would be sucked out and not in at those speeds...

If possible, while you still have the Impreza fpr installed, repeat your wideband afr test - this time in 2nd gear and on a level road. I'd be interested in seeing whether your results will be the same. :)

-Chike

[Chiketkd]

...after having the Impreza fpr installed on my car for over 4 weeks and doing some wot runs today:

http://www.subaru-svx.net/photos/files/Chiketkd/26236.jpg

For comparison, I took a pic of the tip on my wife's stock '02 Lancer ES:

http://www.subaru-svx.net/photos/files/Chiketkd/26237.jpg

While my tips have more visible soot in them, modded turbo'd cars (WRXs, Evo's, SRT-4's) running afr's in the 12:1-11:1 range normally have the stuff caked on in there...

-Chike

[longassname]

I've made a nasty little discovery you won't be too happy to hear. Anyone that was paying attention to the stage III development thread want to guess what's responsible for that lean out above peak power at 5600ish rpms? I'm about to get into doing the final software for stage III so I'll have exact #'s for you soon to verify this (I've made some guesses and interpolations here and there in the prototype software)...but it seems the factory mass air meter actually maxes out in a stock svx. The afr plots go north above 5600 rpms because the maf meter is maxed out.




Chike,

I have that same fuel consumption vs cylinder pressure plot in my locker. :-) As far as I know, the 2.5 RS fpr is working fine. I haven't looked at the vacuum line though. I haven't touched the fuel pump in any way. I suppose its possible that the ram air is having some effect, but keep in mind that the ecu does not just blindly add fuel. It meters fuel based on the MAF sensor reading (among other readings), so if the ram air is somehow messing up airflow at high rpm, the MAF would see this, and the ecu would add less fuel accordingly.

I'm fairly convinced that the afr reading is representative of what the SVX ecu is programmed to do. The other EG33 afr readouts from dyno runs that I've seen (SVXRide, LAN) show the afr progressively richening as the rpms increase. And if I look at the afr readings from your dyno runs, I see the same basic trend too. The afr on your car does richen as the rpms increase, and at peak rpm, there is a slight lean out. My afr runs show the same thing, and so do LANs.

As deruvian said, a little more power may be possible with the 2.5RS fpr by leaning out the mixture a bit at higher rpm using an SAFC-II (or something like it).

[Chiketkd]

The afr plots go north above 5600 rpms because the maf meter is maxed out.
Holy cow! That'll be crazy if a relatively stock 230+hp EG33 can max out the MAF!!! :eek:

-Chike

[deruvian]

I've made a nasty little discovery you won't be too happy to hear. Anyone that was paying attention to the stage III development thread want to guess what's responsible for that lean out above peak power at 5600ish rpms? I'm about to get into doing the final software for stage III so I'll have exact #'s for you soon to verify this (I've made some guesses and interpolations here and there in the prototype software)...but it seems the factory mass air meter actually maxes out in a stock svx. The afr plots go north above 5600 rpms because the maf meter is maxed out.

LAN, my new question to you is: Would it be beneficial to try and mount an upgraded MAF meter on a stock SVX, if the OEM meter is maxed out in stock form? Getting that top-end AFR leaned out on a stock SVX might show some slight power gains at peak horsepower RPMs. THAT is always a nice thing. Please, educate us on the subject.

[BigBlueSVX]

And if installing an upgraded MAF (like your Nissan one) would make a difference on a stock (or slightly modified) SVX would it be possible for you to release another version of the Stage 1 code calibrated for a certain upgraded MAF?

[Chiketkd]

LAN,

I'm going to add myself back to the OBDII Stage 1 sign-up list as a 'possible'. If your chip can make the necessary corrections for the MAF, richen the afr to around 12.3:1-12.5:1 in the upper rpms and only slightly advance the timing...I'm in. ;)

-Chike

[longassname]

mbtoloczko, since you have the get up to log analog data with your wideband software how about logging the maf signal? It's the wire. That'll be a quick and true way to see if the maf is in fact maxing out at 5600 rpms. The max will be 4.8 volts not 5.12. I'm curious to see if the meter goes up to the full 5.12 or not but anything at 4.8 or above will read the same in the software. The table values for 4.8, 4.88, 5.6, & 5.12 are all ffff-it's maxed out mathmatically whether the hardware is maxed out or not.

[alltrac]

Time for a Z32 MAF

[Chiketkd]

Time for a Z32 MAF
I'd hold off on that until LAN has released his OBDII Stage 1 chip. Depending on the capabilities of his tuning software, his performance ECU may be able to take into account voltages above 4.80...

Either way, if you change the MAF, the ECU would need to be re-programmed. Maybe LAN would be able to release two chips - one for the stock MAF, and one compatible with a Z32 MAF. ;)

-Chike

[Chris]

I've made a nasty little discovery you won't be too happy to hear. Anyone that was paying attention to the stage III development thread want to guess what's responsible for that lean out above peak power at 5600ish rpms? I'm about to get into doing the final software for stage III so I'll have exact #'s for you soon to verify this (I've made some guesses and interpolations here and there in the prototype software)...but it seems the factory mass air meter actually maxes out in a stock svx. The afr plots go north above 5600 rpms because the maf meter is maxed out.

This does not suprize me one bit. Got any ideas for a fix?

[NeedForSpeed]

This 'discovery',

Bad, bad bad news for 5mt cars today, great news for all cars tomorrow! Raising the rpm limit is useless if the SVX maf is maxed at the power peak at 5600 rpm. I always felt that my 4EAT car was strong until 5600, and then just going nowhere and wasting time up to the shift at redline, relatively speaking. Do the 5 speeds feel flat from 6000 rpm up?

Would the SVX have a higher power peak in stock form with a bigger MAF?
With a bigger MAF and upgraded injectors? Let's hope we find out :)

This 'nasty little discovery' is actually good news for the future of 'LAN inspired' SVX power. EACH STAGE MUST COME WITH AN UPGRADED MAF [or programming for a 'standardized' upgraded maf], UNLESS LOW SPEED POWER AND DRIVABILITY IS THE ONLY GOAL. [NOT!]

Stages 1 and II could also provide upgraded [affordable] injectors if the stock injectors are near maxed as believed. Stage !!! already has the MAF, monster injectors and fuel pump, solving the limitation.

If each Stage supplies the same 'standardized' MAF and the appropriate injectors for the Stage, the door is open to experiment with rpm, cam timing, airflow, increased displacement, etc, etc. Stage 1 should have enough MAF and injector to support 300+ hp, a 30% gain.

Consider the SVX possibilities!!!

Anyone wanting more NA power than stock MUST HAVE STAGE 1 as a foundation. Anyone wanting max power will need STAGE !!!

Current Stage 1 programming is delivering power and drivability in the lower ranges, but the MAF 'discovery' opens the door to kicking up power to redline and beyond. Stage 1 REMIX with MAF and possibly injectors should kick a stock car every time, especially a Stage 1 REMIX 5-MT. Now maybe we will see stock weight cars with a few mods fun consistantly in the mid-90s mph range in the quarter mile. eg33 engine development begins now.

After LAN installed and programmed the MAF and the huge injectors, he implied that the car was strong. I wonder if the car felt better from 5600 to redline?

What do you say Michael? Stage 1 REMIX programming with upgraded 'standardized' MAF and upgraded [affordable] injectors, for the masses?

Somebody pinch me!


I've made a nasty little discovery you won't be too happy to hear. Anyone that was paying attention to the stage III development thread want to guess what's responsible for that lean out above peak power at 5600ish rpms? I'm about to get into doing the final software for stage III so I'll have exact #'s for you soon to verify this (I've made some guesses and interpolations here and there in the prototype software)...but it seems the factory mass air meter actually maxes out in a stock svx. The afr plots go north above 5600 rpms because the maf meter is maxed out.

[Earthworm]

What about opening up a bypass pipe to divert air around the MAF sensor? Everything would need to be carefully recalculated (possibly run 2 meters to calibrate the readings from the meter with the diverter pipe).

[drivemusicnow]

what some people do in the DSM world is they actually let unmetered air in a specific amount. (called a "hacked MAF") you then richen the Air/Fuel ratio a specific amount to compensate for that extra unmetered air. the problem some of the people have with this is that at idle, if its easier to pull the "unmetered" air then it is to get "metered" air, then you're idle and low rpm is way too rich, and runs badly. I think the way to get around this would be to instal and extra filter, such that there is "resistance" to pulling that air into the intake tract.

however, I think we may get better results just putting a very small resistor in line with the MAF wire. this would lower the voltage by a set amount (given the amperage stays the same, which it should) and would allow you to use the extra ability of the MAF, such that when it reads 5.12 volts, its sending 4.8 (since all the values are the same after 4.8 anyway)

^I'm not really thinking to well right now cause i'm extremely tired. check that and make sure i'm not too much of an idiot.

[Earthworm]

however, I think we may get better results just putting a very small resistor in line with the MAF wire. this would lower the voltage by a set amount (given the amperage stays the same, which it should) and would allow you to use the extra ability of the MAF, such that when it reads 5.12 volts, its sending 4.8 (since all the values are the same after 4.8 anyway)I thought of this but then I realized that would just make things worse. Currently the MAF can measure between 0 and 4.8V. The resistor is going to make that range even smaller.

What we need is a way to accurately measure more air flow utilizing the existing equipment or else swap for equipment that will. We already know the stock MAF will not measure accurately over 5600RPM regardless of what you do to the wiring/ECU.

[longassname]

I didn't mean to inspire a hijacking of the thread. I was just suggesting that the maf voltage output be the next analog data he log along with afr.

[mbtoloczko]

mbtoloczko, since you have the get up to log analog data with your wideband software how about logging the maf signal? It's the wire. That'll be a quick and true way to see if the maf is in fact maxing out at 5600 rpms. The max will be 4.8 volts not 5.12. I'm curious to see if the meter goes up to the full 5.12 or not but anything at 4.8 or above will read the same in the software. The table values for 4.8, 4.88, 5.6, & 5.12 are all ffff-it's maxed out mathmatically whether the hardware is maxed out or not.

Michael, I'm definitely going to log the MAF voltage reading. I have a suspicion that the slight lean-out at WOT peak rpm is due to the MAF maxing out, but some of my data suggests otherwise. The last plot I posted on the 1st page shows the afr at about 1/2 throttle (vs WOT) all the way out to 6500 rpm, and even here the afr leans out a bit near max rpm. So, I wasn't going to say anything about the MAF possibly maxing out until I could get some concrete data. I'm super busy at work right now, so I don't think I'll be able to get the data until mid-June.

[SVXtasy]

I log data for both wide band and MAF voltage on my CAMP system. But this does not help much due to the fact that it is on a turbo car.