AO

I sit corrected.

Big Dave

Hey...you coming on Thursday? I want a ride!!!

AO

I don't know. Need to check with the wife to see if she's flying. If she's not flying, then I'll be there. Otherwise... sorry, we'll have to do it another day.

I really need to spend some quality time with her and the kids. A couple hours should do it.

DR

Mike,

Here is a simple explanation for how this works..

The Active MAF (drivers side) is also where all of the idle air is metered from and then thru the idle stabilizer (both TBs are closed) so Idle characteristics are just like stock, no real tuning changes needed (except for adjustment for the 30 lb Injectors). When you go off Idle and crack the TBs the active MAF reads the incoming air (half of it) which gives you your airflow calibration. Then it is a simple task of mapping the LH to compensate for double the airflow. The reason we go thru the expense of using the dummy MAF is to ensure we have a close to an exact airflow pattern thru both sides so calibration is basically constant.

Part of the beauty of this design is I am only using 60% MAF signal at 450+ RWHP (just 1 stock MAF will MAX out around 400RWHP or so) . You can then do the math and see what this air intake metering system is capable of before maxing out the MAF system.... A HECK OF A LOT!! :-) This gives room to grow without changing or modifying the MAF system.... maybe 600 RWHP or so before additional mods are needed.

One note, this does afect the timing calibration some what due to the lower MAF signal being sent to the EZK brain, but the upside is that just means once John has the EZK upgrade done I am confident there is plenty of tweaking that can be done to squeeze even more safe power out of my system.

Big Dave

928drvr86.5

Hey Dr,


Let me start by saying that i am bummed that i missed SITM this year, it would have been great to see Andy's install. I have a question regarding the 85-86.5 32V models and your twin screw kit. I have read and understand from your site that your setup will infact work for use on the early 32v models but i also have read that the Speake's Sharktuner is only compatable with the 87+ model's LH, you can probably see where i am going with this. How does the MAF trickery work with our models if the Sharktuner cannot be used? Sorry if the answer is obvious, i am still learning about this SC stuff and studying the Corky Bell book. LOL

DR

Ben,

Althought I would certainly prefer to use the ST for my final tuning, I know others that can remap 85-86 computers... and there are always more than one way to skin a cat. When we do our first production 85-86 install (#10 or 11??) all will be reveiled just as we have with the 87-up version. I prefer not to spill all my tricks until the time is right :-)

>i am still learning about this SC stuff.

We all are!!

> and studying the Corky Bell book. LOL

Hmm, maybe I should read that sometime,...anyone have a copy I can borrow?

AO

I was going through my pictures and just had to share this one. When we went to install the wide-band O2 sensor, the plug was siezed in the bung. DR took out hte plasma cutter and made short order of it. What a cool pic!

heinrich

Yeah you sure don't want a plug seized in your bung

John Speake

Hi Dave,
The EZK is nearly ready for some first trials :-) We have been doing some final tweaks this week.

One interesting fact has emerged from the EZK work - as soon as you hit the WOT switch then ignition advance is the same from 50% load to 100% load. So this may explain why you still got such good results, even accounting for the "recalbrated" load signal that feeds the MAF.

DR

John,

>The EZK is nearly ready for some first trials :-) We have been doing some final tweaks this week.

COOL, GIMME, GIMME!!!

>One interesting fact has emerged from the EZK work - as soon as you hit the WOT switch then >ignition advance is the same from 50% load to 100% load.
>So this may explain why you still got such good results, even accounting for the "recalbrated" load signal that feeds the MAF.

That is very interesting, can't wait to try tweaking the ignition!!

Thanks again for all of your hard work and for making all of us such a great and valuable 928 product. My life the last few months would have been a LOT harder without it!

John Speake

Hi Dave,
I'm writing the User Manual for the EZK ST this afternoon...

The whole ST project has been shared between Niklas and myself. Without him it would never have happened...

Now back to those screenshots !

Flott Leben

John,

Am I correct when I state the following (very simplified, I know):

1) the MAF merely sends a voltage out to both the LH and EZK based on the air flow it sees across the hot wire, then:

a) the LH receives this voltage and based on the fuel map on the EPROMS decides how much fuel to supply (duration and width of pulses) and

b) the EZK receives this voltage and based on load (throttle body position) and a set timing mapping scheme decides how much to retard timing?

I know there are probably other sensors involved in the process but is that generally it?

Questions:

Does the EZK use EPROMS to set its timing mapping scheme based on MAF (and other sensors) voltage?

If you can reprogram both the LH and EZK to react to the MAF voltage according to new mapping schemes, it doesn't matter what the voltage input from the MAF is, all that matters is what the LH and EZK are programmed to do with that certain input voltage, right?

So, with Dave's dual throttle body set up, only half the air is traveling over the MAF hotwire and therefore sending only half the voltage signal. But the LH and EZK will interpret that voltage as twice the air and adjust accordingly. Therefore, the intake can supply up to twice the stock MAF’s normal air capacity and the system can still handle all the monitoring functions. Wow!! Hats off to you, John and Niklas, for producing these devices. You have made so much possible with use of the stock LH, EZK and sensors. All you need is new EPROMS.

Dave, I can now see why you are using a dummy MAF. You need to have the exact same volume of air coming from both intakes since one side is not being monitored at all. The fabrication of the intake and making one side as identical as possible to the other is crucial. I bet you probably even measured the length of the two air tubes to make sure they are precisely equal as well! Very nice work.

mspiegle

Makes perfect sense. Very clever idea too! Just like that ingenius usage of the alternator pulley

Flott Leben

One other thing, Dave (and John would have to build it, I guess): Did you ever give any thought to using two MAFs and desiging a "black box" that wold read both voltages, average them and send the averaged voltage signal to the LH and EZK?

Dave, that is probably more complex than need be but wouldn't it provide a more accurate air monitoring circuit? Also, couldn't you then substiute newer (less expensive or more reliable) MAFs for our 20 year-old-engineered stock ones? All that would matter is that the final, average voltage signal that comes out of the black box is compatable with our computers, right?