now every body knows the maf sensors for the turbos and a couple for the na cars but nothing is said or done with the map sensors (except huntley superchargers). now we all want more hp and so do i but how do we get it from all of these sensors including the map sensor i am doing some looking on the web to see if such a conversion is do-able. i'm no electrical genious and a slight understanding of how the dme works, but if we could graft this little marvel onto our systems then i think we could tap some hp (not much but at least it would free up some options for filter location, size of injectors, and no restricting afm.

i was looking at the parameters for the afm we have and it looks like the map for a 1bar application might work for na cars, it has a 0 volt to 5 volt range and im sure that a little tinkering could bring it into the operating parameters of the afm, now as far as the temp sensor that resides inside the afm i gues a small thermalcouple could be placed into the steam of the intake to get that reading.

ok which one of you porsche tuners want to go first with this

also this little device cost anywhere from $20 - $60 new thus eliminating some of this bull**** cost of these so called performance add-ons

hers what i am thinking we take the afm out and the boot as well run a intercooler tube to the front panel (dont forget the crancase line from the oil filler tank)then attach your filter inside the panel (youl have to be kinda resourcefull here) drill and tap the manifold for a small nipple (for the map sensor) attach the map sensor where ever you want ( its about the size of a credit card ) now caome the hard part making a pigtail for the map from the existing afm plug; oh yeh forgot about the temp sensor well thats why i wante to get you guys involved, ive noticed on some of the bmw boards they like to do this kind stuff (sorta rice)

and forget about all this stuff about arc1 -2 -3 or whatever they call them, if its set up right for the specific application it wont need adjusments

i figure if huntley can do it for the surpercharged cars then it can be done with others as well

well tell me what you guys think <img src="graemlins/jumper.gif" border="0" alt="[jumper]" />

 

The only problem I see is that the DME doesn't have the correct calculations algorithm to use a MAP sensor. Both the stock AFM & MAF upgrades output a fairly linear output that corresponds to total air-flow. Combined with the air-temp sensor, you can compute a total air-mass, and therefore a corresponding duty-cycle on the injectors to match an appropriate amount of fuel.

However, a MAP sensor, only measures the absolute pressure inside the manifold. So at -5psi in the intake, you could be coming off idle or at 5000rpm. Both of which would have complete different air-masses flowing through the engine. In order to get a fuel calculation, you need to use the manifold-absolute-pressure data, along with RPM, and air-density and temperature to compute the air-mass. I think the Huntley SC kit uses a top-secret 'black box' piggy back computer that does that calculation and outputs a linear signal for the stock DME.

 

Danno thanks for that tid bit i hadnt realized that problem, but couldn't put a pot or even change the tps to do the linear measurment for the dme, as far as the air density the afm that we have now doesn't mearsure density just the temp (well in a sense it does because of the given size of the hole and the position of the door and the temp ) but if you were to change the door ie.. put a pot on the throtle valve it would then give the same as the door in the afm then you would have to tweek the output no.s because the throtle valve has a bigger opening than the afm (or does it).

i am tring to make this as simple as posible and as cheap as posible

Danno keep me in line with this cause i do think too much about ****

 

[quote]Originally posted by Danno:
[QB]Both the stock AFM & MAF upgrades output a fairly linear output that corresponds to total air-flow.[QB]<hr></blockquote>

From what I've read, I don't think the maf output is very linear. Check the graph on this
<a href="http://www.flash.net/~rfm2/massair.htm" target="_blank">site</a>. Does anyone have the data from an AFM to compare? I would think the ouput would be fairly linear from one.

Hey Danno, how is the SDS plug in boxes coming? Keep us updated.

Rob

 

but couldn't put a pot or even change the tps to do the linear measurment for the dme,

But that still doesn't give you a total air-mass number to use for fuel-calculations. That would just indicate the throttle position. But at say... full throttle and 0.9v output on the TPS, you can be flowing 50cfm or 150cfm. So the throttle position doesn't have anything to do with the air-mass that's going through the engine. That's why on the NA car, the AFM signal is so important.

To use a MAP sensor, you definitely need an extra 'black box' piggyback computer to do the air-mass calculations and output an AFM/MAF-like signal to the DME. Sorry, by 'linear' in my last post, I should have qualified with a 'faily lnear compared to MAP sensor output'.

Besides, on an NA car, there's not going to be much of a difference between uprading to an MAP sensor over an MAF sensor anyway. In fact, freeing up the intake on an NA car won't give you much. It will take away from the low-RPM torque and give you high-END HP, but your overall speed will be about the same. For the price of these conversions, you'd get way better performance by going to higher-compression pistons like the later cars.

If you must free up your intake, then do one of these MAF conversions:<a href="http://forums.rennlist.com/scripts/rennforums/ultimatebb.cgi?ubb=get_topic&f=15&t=001088" target="_blank">MAF on an NA 944</a>

 

hey Danno i saw that maf conversion before, thats what got the wheels inside my head turning.

i'm not tring to get more hp from the a map conversion just want to clean up the engine bay and put the filter in a colder spot.

i'm looking at the split second site and wanted to know if they could help with this endevour and keep the cost down. also i was looking into a maf conversion when i remembered the map that huntley did. i thought that by removing another big component that it would be better for the motor to breath

however; i do want to do something like a maf/map just to get this damn barn door crap off my intake i do think it is a bigg restriction in the system, also i dont see the rationale of a oversized thotle body in this intake path when its still blocked by this door.

i'm actively looking for a solution that fits within my budget (which is kinda like $5.00 at the time) but if you could help with grafting a maf i would like that very much. what is basicaly needed is the part no. to a maf sensor that would be compatable with our sys. i was looking at a ford maf but dont know which to get.also the pin info and the resister info for the inputs and outputs.

right now i'm getting a headach, so thanks for now

 

hey Danno had a though <img src="graemlins/a_smil17.gif" border="0" alt="[blabla]" /> you said in you first reply about the dme needing some more info that the map wasnt giving it, like rpms, well isnt it getting that from the picups at the rear of the engine? also air temp, putting a temp sensor in the air stream was in my first post. and also the tps has a cut off ****ch when at idle (i dont know what it cuts off ) but it might be helpfull. now you had said that the map would kinda read eronious when comming off idle to wot and vise versa (not quoting but pretty much the jest) but wouldn't the map sensor detect this in the change of the pressure inside the manifold, if anything i think it would send the info to the dme faster than the afm door would (maybe thats the problem)

heres my thinking the map and the door side of the afm are reading almost the same thing the map is reading the pressure of the air and the afm is reading the speed of the air. and i would think that they are porportional to each other or maybe inversely porportioned

now as far as the density well we've got the temp and got a fixed orifice (throtle body) so what would be needed is calibration of the map and air temp sensorto get the specific density for the TB
if the siganals are right from the map&temp sensores then the computer can cypher the rest of the parameters i.e. speed,spark,and all the others

maybe <img src="confused.gif" border="0">

 

hey Danno had a though you said in you first reply about the dme needing some more info that the map wasnt giving it, like rpms, well isnt it getting that from the picups at the rear of the engine?

Well, the RPM data is there, but the problem is with the algorithm (calculations) the DME uses. It just won't work with a MAP sensor. The DME simply uses the RPM for reference to the fuel-tables stored in the chip:

DME: (AirFlow&Mass +AirTemp +WaterTemp) = Load X RPM inLookupTable = Injector Duty Cycle.



And the algorithm for the MAP may look like:

MAP: [(AbsolutePressure * RPM * FuelValue) +AirTemp +WaterTemp] = Injector Duty Cycle

So the two processes of computations to arrive at the injector duty-cycle (therefore fuel-volume) is completely different.

heres my thinking the map and the door side of the afm are reading almost the same thing the map is reading the pressure of the air and the afm is reading the speed of the air. and i would think that they are porportional to each other or maybe inversely porportioned

I think this is where you're getting stuck. The MAP output and AFM/MAF output are not 'almost the same thing' at all nor in proportion with each other. For example at 1500rpm full-throttle, AFM/MAF output may be 0.2v and at 6500rpm full-throttle it may be 4.75v.

A MAP sensor on the other hand, may be outputting 1.0v at 1500rpm full-throttle and 1.0v at 6500rpm full-throttle. So a MAP sensor is actually more of a load sensor rather than an air flow or mass sensor.

So to come up with an air-mass/flow number to plug into the DME AFM input, you'll need an additional box that does the AbsolutePressure*RPM calculation first. Something like a Link ElectroSytems AFM-link product. But after spending $500-600 to install a MAP-sensor with this 'black-box' interceptor, it's going to be tough to swallow all that for a 1-4hp gain, if even that.

Just do the Volvo MAF conversion and you will have gotten 99% of a MAP conversion.

 

boy, i'm in way over my head, i need to swim back to the shallow end.

Danno thanks for your insight about these things. glad to have this board for the tech lessons and not mention the time and money saved.

you said the volvo maf, like to one in the earlier link? that thing is monsterous, i think i'll just make a pigtail for my afm and stick it under the nose somewhere.

 

Not to let the cat out of the bag or anything but we will be offering our, as Danno said, 'ultra top sevred black box' in a MAP conversion kit for all Porsches very soon. <img src="graemlins/jumper.gif" border="0" alt="[jumper]" />

 

oh yeh how much is the conversion?

 

Two things:
1. There was talk a while ago about burning custom chips for the motronic system. The company that provides the software for burning your own chips does map conversions for Porsches and is working on a 944 upgrade. The site also details the types of systems available and the strengths and weaknesses of each system.

2. At Seattle dyno day I had the privilage of watching a modded 951 run with staight intercooler pipes and the AFM located in the same position as the MAF's get moved to. It would seem that the HP and torque benefits can be largely recognized without the air mass conversion. This setup also cleans up the area in front of the engine. One other trick was the owner removed the brazed coolant pipe with a flexible hose from a 924 of some type. This further improves access to the front of the engine.

 

doyou know the name of the company that is doing the custom chips for the maps?

 

No prices just yet for the MAP conversions but somewhere around $800+ <img src="graemlins/jumper.gif" border="0" alt="[jumper]" />

 

hey Derrek can you give the pros and cons between the mafs and the maps conversions please thank you