V2Rocket

quick question: what would people recommend as the best standalone for the money, that can be adapted to different engines?

Fishey

Haltech IMHO is one of the best standalones on the market right now and comparing it to something like motec its way way cheaper.

333pg333

Everything is way way cheaper than Motec. Motec is obviously still the market leader but these guys are greedy. By comparison all the others are cheap. The Vitesse gear also works very well.

I really think you need to state what you want to do with your car and be realistic about it. In other words if you go to the trouble of modifying it do you think you will be more attracted to doing track events? If so, then there will be other costs involved as you know. I am more convinced everyday that having a fast and usable street car in Australia is pretty much redundant. There is too much policing and the concept of driving for entertainment has become a crime. So therefore get your kicks on the track...which brings us back to the reason for doing this.

Henk, you may need to translate some of that for us.

Mark944na86

Actually, the bit about "€ 6900, - VAT included" I could translate myself. (VAT in Holland is 19%, so ex VAT is about € 5700 -- about US$8000!)

Also, note "tubo lag" is "turbo hole" in Dutch. Gotta laugh!

mikey_audiogeek

Hi Eric, you're at the same point as me.

My findings are:
1. Motronic ain't bad. Tuning the Motronic can be done using tuning tools from Vitesse, FRWilk, or TunerPro.
2. AFM's ain't bad. No need to replace the AFM unless it is maxxed out. I'm about to do some datalogging to see if this is the case.
3. www.mapecu.com for a MAP conversion, I have no experience with it though.
4. TonyG makes a valid case for the GM LS1 computer as being the best choice of aftermarket ECU for the 944.
5. Wolf make a plug 'n' play ECU for the 944 racing series in Oz. I contacted them and they said they could supply an "unlocked" ECU for the same price.
6. Tuning is everything. Find a good tuning shop and then follow their recommendations.
7. Superchargers are cooooooooooooooool!

Mike

Eric_Oz_S2

Mike,

I've heard the AFMs can get upset by too much airflow or disturbance caused by the BOV. Not sure if this is really the case. I would presume that the AFM must go before the supercharger, whereas a MAP must go after.

The Wolf ECU for the challenge series is for a 2.5NA - not an S2. I don't think it would be plug and play for the S2 - different Motronic System.

mikey_audiogeek

Hi Eric,

I was looking at Rotrex's preferred arrangement with the throttle butterfly on the inlet of the centrifugal supercharger - this apparently does away with the need for a BOV.

Yeah good point on the Wolf3D - here's the reply I got from Wolf:

Hi Mike,

Sorry for taking so long for the reply, we do an adaptor harness for the 944 but will need some modifications made to the pick up sensor.
These adaptors were made for race cars, so the pick up we use is on the front balance shaft pulley.
The other option is to modify the amount of pins on the fly wheel, this can be done if you require the balance shafts to be left in use.

Regards,
Robbie McQueen

I think we can use our existing crank sensor since the S2 has a 60-2 tooth arrangement which the Wolf can accept. Dunno about the harness and pinout though.

Cheers,
Mike

Eric_Oz_S2

What in the stock software would cause problems. If the AFM is on the inlet side and running low boost (and not "maxxing" out the AFM) what do you think would cause problems?

That UK person is (I think) Peter Empson. I have been in contact with him - he is using the Scivision MAF.

Mark944na86

You will have to explain this to me. The stock AFM simply reports the angle of the barndoor to the DME as a sensor input -- no? In what way would the boost level affect this ("maxing out") one way or the other?

Eric_Oz_S2

The AFM can only flow a certain volume before any further increase results in no further increase in output voltage. Therefore once beyond this value there is more air entering the engine, yet fuel and ignition remains unchanged - so potential to run lean. For example at peak power (5800 rpm) volume of air entering engine (atmospheric pressure) = 1.5 l/rev x 5800 x 60 = 522 m3/hr. If pressure increases (boosted) by say 0.4 then Vol = 522 x 1.4 = 730 m3/hr. I had a datasheet for the AFM, but can't find it. I think the capacity (to read flow) of the AFM is around 500 m3/hr - so it is already maxed out.

Out of interest, the S2 injectors flow 300 cc/min = 225 g/min = 54 kg/h (for 4). At atmospheric, mass of air at 5800 = 522 x 1.3kg/m3 = 679 kg/h. So the AFR = 12.5. So you can see the injectors are nearing the limit of engine power without boosting. If you add 0.4 bar boost, the weight of air increases by 40% and the AFRs lean out too much. Another rule of thumb for engine power is:

hp = lb/hr x 2.04, which gives about 240hp (29.2 x 4 x 2.04) for the S2. Similarly, using turbo injectors (37.6 lb/hr) gives you get about 305hp. 968s gives 33.9 x 4 x 2.04 = 275hp.

This gives an idea why with some tuning you will not get a power increase without uprating the injectors (or fuel pressure).

fast951

The stock software checks many variables under various running conditions. One of the variables is the signal from the AFM. When you go to forced induction, the AFM signal will be higher than in a NA form at the same RPM (forced induction = more flow or a higher AFM voltage).

Peter is using the Sci MAF, which in reality converts the MAF signal to look like a AFM. The DME still operates as if a AFM is being used (not a genuine MAF conversion).
Peter is using the Vitesse Software for his supercharged engine. In our software, we handle the various conditions associated with the forced induction.

Mark944na86

Pardon my ignorance, but I didn't realise the AFM sensed or measured flow directly at all -- I thought it just reported the position of the flap via a voltage, and the DME inferred the air flow on the basis of this information.

So how does the AFM actually measure air flow? A MAF uses the cooling of a heated wire; what's the actual mechanism used by the AFM? (I was under the impression that the reason MAFs and MAP sensors were in fact superior to the AFM was because they did actually measure air flow/volume directly.)

Eric_Oz_S2

Mark,

Technically the AFM measures the angle of the vane. For the later AFMs, the angle is proportional to the voltage. The voltage is not linearly proportional to the flow - the ECU works out the "flow" based on a set of relationships provided by the AFM manufacturer. The ECU doesn't actually want to know flow though, it wants mass (to work out fuel ratio), so it uses the intake temp sensor to work out the air density and hence the mass. However, when you supercharge the temperatures also go up in the intake air, and hence there is actually less mass of of air then what the ECU thinks (notwithstanding the AFM may be beyond its measuring limits).

Mark944na86

Thanks for the detailed reply, Eric, but as you can see from my post above, my conceptual problem might be more basic than this. I didn't think extra flow in itself would increase the AFM voltage, only a change in position of the air flap would do that, i.e. WOT returns max voltage regardless of the volume of air actually flowed.

fast951

Let's look at the big picture.
With forced induction, more air (compared to a NA form) goes through the AFM at the same RPM. With more air going through the barn door opens more and generates a higher voltage.

Out of curiosity, what do you think the AFM (Air FLow Meter) is measuring?