You can use a MAP and MAF with dannos map kit, just add a MAF and change some dip switches in the Link box, then probibly some programming.

Right Danno?

 

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by fast951:
<strong>I'm working on a setup that uses both the MAF and a MAP sensor for the 951. It'll be released soon.</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">I take it that will be a piggy back system??

 

Yes it will be a PB system. MAF to read Mass Air and to control fuel.
MAP signal can be used for:
* additional fuel tuning. (based on LOAD/RPM and BOOST)

* Water injection control (based on LOAD/RPM and BOOST) OR
* Boost control

* It can be used to activatre an external relay, light, rev-control based on a preset boost limit.

 

To bad I really want to get rid of the stock setup!

 

"You can use a MAP and MAF with dannos map kit, just add a MAF and change some dip switches in the Link box, then probibly some programming."

The original AFM-Link product that we used to develope our MAP-kits was a generic off-the-shelf product that had been around since 1992. It could be used as a standalone MAP-based AFM-simulator, or as a piggyback signal-massager to adjust the incoming signal from the stock AFM or an aftermarket MAF-sensor.

However, due to its generic nature, this box took a lot of programming to set up for the 951. What Link-NZ had done after we brought a lot of attention to the product (and controversy) was to create a second-generation 951-specific box. Whereas the original box used mathematical equations to compute air-flow at any given MAP-pressure and RPM, the 2nd-gen. box had all the actual air-flow values from the stock-AFM pre-programmed into it. This was done through datalogging a stock 951 AFM and burning its response-curve into the MAP box. So on most cars, the AFM-Link MAP-box is shipped with zero adjustments and can emulate the AFM precisely, thus no programming or corrections needed. In cases with cars having upgrades or non-standard configurations, some adjustments can be dialed in.

At the same time, the signal-massaging function was split off into its own product, the <a href="http://www.link-electro.co.nz/interceptlink.html" target="_blank">Intercept-Link</a>, which is the basis of our <a href="http://www.gururacing.net/DigitalMAFupgrade.html" target="_blank">Digital-MAF upgrade</a>. This provides 144 load and RPM-based zones for 3D adjustment and gives much finer resolution and more range (+/127%) than a 4-knobbie rheostat adjuster.

 

ah, but with the power-perfect computer (over, say an arc2) you can adjust the resolution of the knobies (pots)

i feel ignorant, but i still don't see how pressure and flow corolate (which is why i got scared off of MAP in the first place). if my kokeln street turbo flows more air at 14psi than a k26/6 how does that MAP sensor accomodate / adjsut for that?? please enlighten a map n00b...

 

While I was never as good at Newtonian physics, gas laws, etc., as I was at electrical physics, I was under the impression that the MAP sensor would be guided by PV = nRT, in which the pressure in the system would be related (inversely) to the volume being pushed through the system, and also be effected (direcly) based on temperature also. This leads me to wonder why a MAP sensor needs a temperature sensor at all, unless its resolution isn't accurate enough to measure small temperature fluctuations and react to them?

 

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica"> PV = nRT, in which the pressure in the system would be related (inversely) to the volume being pushed through the system </font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">Well that doesn't make much sense, giving that the turbo GENERATES pressure by pushing air through the system..

Now I'm confused

PV=nRT makes perfect sense to me when I think about a balloon...if the temp goes up, either the ballon is going to expand ( P increases ), or it'll grow bigger ( T increases ). If you squeeze the balloon ( increase P ), it'll either get smaller or heat up

Throwing out the constants really just leaves you with PV = T

which clearifies why you need a temp sensor in a map kit, but shouldn't pressure be related DIRECTLY to airflow?

 

Every time the intake valve opens, the cylinder takes the same size "bite" (at a specific, single rpm). If you give the open cylinder denser "food" it will ingest more with each "bite" or flow more volume at the same rpm. If you know the pressure and the rpm (and your motor's rpm specific volumetric efficiency) you know the volume.

 

"Throwing out the constants really just leaves you with PV = T

First, the ideal gas law is far from ideal. The 'ideal' part assumes a perfect gas molecule with zero mass and zero volume. Thus it doesn't work for cases of high heat or high pressure and correction tables must be used. Some of these factors can be adjustments of over 100%!!!

"which clearifies why you need a temp sensor in a map kit, but shouldn't pressure be related DIRECTLY to airflow?"

This is the same problem as trying to compute compression pressure based upon just compression-ratio. You've got two variables and only one constant. You need another equation with one of the first variables held constant.

Ok, so let's see how this ambiguity fits in with real-life conditions:

"but i still don't see how pressure and flow corolate (which is why i got scared off of MAP in the first place). if my kokeln street turbo flows more air at 14psi than a k26/6 how does that MAP sensor accomodate / adjsut for that?? please enlighten a map n00b..."

Measuring pressure can be tricky because it will be different depending upon how and where you measure it (for the same flow-rate even). Bernoulli's laws show that higher flow-rates will indicate lower pressures when measured at the side of the tube. However, if you're sitting in the middle of the tube, then higher flow-rate will definitely hit you harder.

Let's say you have a turbo that's flowing a constant 350cfm at a steady-RPM. Measuring pressure right at the MAF-sensor will show a vacuum. Taking a pressure-reading at the turbo's outlet will indicate high-pressure, say... 20psi. At the inlet to the intercooler, pressure may be 21psi with 19psi at the outlet. Pressure going into the throttle-body may show 19psi, but after the throttle-body it will be 18psi with higher-velocity. All of this is at exactly the same flow-rate of 350cfm going through the turbo.

As you can see in the previous illustration, pressure is really an indication of restriction in the system, which stretches and squeezes the air through like stringy taffy (changing density of air). Let's say we have the same 350cfm flow as before, but we put in a restrictor plate with a tiny 1" hole right in front of the throttle-body. Pressure-readings in the intercooler-pipe now may be showing 25psi due to build-up before the restrictor plate. However, pressure in the intake-manifold will have dropped to 13psi. In this case, a lot less air will be flowing into the combustion chambers.

What a more efficient turbo does is to not heat up the air as much when it leaves the turbo at the same boost-pressure as before. At 14psi with stock K26/6, you're looking at an exit temperature of around 280-290 degrees-F. After it's gone through the intercooler, you're still looking at about 150-160 degrees. A more efficient turbo will be in the 100-110 degree range after the intercooler. This lower-temp mixture will be denser tha before (have more O2-molecules per volume). But more importantly, it's less detonation-prone due to the lower temps. This means you can turn up this efficient turbo to 18psi and have the same exit temperatures as stock at 14psi.

How this works with a MAP sensor is related to where you measure the pressure. The pickup for this is inside the intake-manifold aimed at the incoming air-flow. This will yield a different pressure measurement than what you see at the intercooler banjo-bolt which picks up pressure at the side of the tube. While at the exit of the turbo, you may be sending out 14psi, the changes in pressure at it goes through the various restrictions in the system will not be the same. The cooler, denser mixture will experience higher restriction as it goes through the intercooler, the throttle body and intake-valves. The stock K26/6 @14psi may end up with 12psi in the intake-manifold at the end where the MAP-sensor measures. The aftermarket turbo @ 14psi would be around 13psi in the manifold due to the higher resistance to its denser mixture.

As Russ mentioned, knowing the Pressure and the Volume ingested (2.5L per 4-stroke cycle), you can compute the mass(n) of the air going into each combustion chamber. So in comparing the stock K26/6 to an aftermarket turbo, you are not actually flowing more volume of air into the engine per stroke (limited to 1/4th of 2.5L per cylinder), but that same volume is cooler and denser. You can work backwards and compute atmospheric CFM flowing into the turbo too if you wanted. In this case, yes, there would be more non-pressurized atmospheric air being ingested by the turbo for the same boost-pressure going into the engine.

 

Oh I see, it's the whole wind-tunnel vacuum before the turbo

Hey Danno, I have a Digital Design and Computer Architecture final coming up...wanna come over to the east coast and take it for me? :-D

 

My main advice is to have a tuneing module. ive got my MAP setup mostly sorted out. The main problem was just a wayy too rich idle, which i fixed, now the only things are some slight on throttle hickups, and backfires when i dont shift right.