ALEX P

This is really interesting stuff. So you simply unplug and remove the Motronic ECU, store it safely. Plug in the Motec with the adaptor harness. Map it to your car on the rolling road and off you go.

This has to be a much more cost affective solution as well as being more appealing to people as it is so easily reversible and doesn't involve chopping the loom about or replacing it.

Does it give all the same benefits as a full 9M type Motec conversion? I can't believe it does as if it did then why justify all the extra cost and trouble of the 'full fat' conversion if the necessary wiring and connections are there in the first place?

So M600 is what something like £2k used, £500 for the 9M adaptor loom and a few hundred £ for a good remap on the rollers and boom, Motec for under £3k right............

alexjc4

Even less with a M48 ecu, they are like £1100 new. I did think Colin said he wouldn't sell the harnesses seperately though.

ALEX P

Really? Why? £500 seems a fair price for such a harness, there must still be a reasonable margin on it too.

We have all seen the benefits of proper management such as Motec but it still takes some justification to drop £6k or so into the car for the privilege. This has all been discussed in detail numerous times before (see below) but I don't remember the option of a simple adaptor harness being discussed.

https://rennlist.com/forums/964-foru...c-v-motec.html

Anyway, I guess this is straying off topic as it was about injectors. I've asked about injectors a few times as I cant understand why run with stock 964 injectors that are near the edge of their performance envelope if you can run with injectors with a higher potential flow rate such as the 951 ones from a 944 turbo and run them at 80%?

I know you already said they run at 193cc/min but just FYI the info on 964 injectors I was given was:


Injectors 964 part # 911 606 120 01 have the following BOSCH # Bosch 0280150731 giving the following specs:

18.4/lb injectors and flow 194cc @ 3.0 bar, with a 21° spray angle for the cone characteristics. The connectors are EV1 type.

@3.8 bar (55.1 psi) = 300-320 hp

alexjc4

That's interesting, I wonder where I got 5bar from, maybe that's on a 964 Turbo?

Still that shows how close to the bone they are.

the rule of thumb of 1cc per bhp I use, which would only give 244bhp at 3.8bar, is based on the car running rich best torque afr of around 12.x (for turbo'd engines), as has been stated our engines actually seem to like lean best torque afr around 13.x so I guess that stretches them a bit.

alexjc4

There's a thread here about injectors on pelican. Post 5 has someone puzzling how it gets away with such small injectors. Confirms the same info: 19lbs/hr 194cc/min @ 3bar injectors running at 3.8bar

http://forums.pelicanparts.com/911-e...e-ecu-etc.html

ras62

I ran these injectors for a little while but the car was running way too rich causing stalling and hesitation at low revs. Up the rev range the car ran fine, the engine seemed both quicker and smoother. The advert says these injectors run on a stock ECU but in truth a remap is required to get the car running properly.
While the increase in flow can be beneficial the spray pattern and atomization is also a worthwhile benefit, but as I say figure on needing a remap.

Eric_Oz_S2

The idle map doesn't adjust itself through O2 feedback very well at all, so your observations are consistent with mine. The wot maps will also be wrong if the injector scaling is not changed in the motronic maps. The wot (for cars with O2 sensors) use a trim map (in the ram not rom) which is what the dme learns is needed to achieve stoich. The trim map is calculated based on the pt maps. The wot maps then are basically enrichment maps that add fuel based on the closed loop learned values (pt trim maps). So if the motronic maps are not changed and larger injectors fitted, the idle will be rich and the wot maps will also be richer than stock. Also, the engine will run very rich until the dme has a chance to learn the adjustments (which will be reset when the battery is disconnected). But as stated previously it will still not learn the wot and idle maps properly.

So, yes you need to remap.

jpar

Thank you, these are the responses I was looking for. Somehow a thread about $200 injectors turned into an ad for $3000 standalone. I would love to do Motec, it's just not in the budget right now. I'm simply looking for another option besides having my stock injectors cleaned, I guess these are not it.

Juha G

The mapping on the stock ECU is based on the flow rate of the stock injectors. The ECU is controlling only the opening time of the injector, based on engine load and other parameters. If you change the injectors with ones that have different flow, the mapping must be corrected too. Otherwise you run either lean or too rich. Sure there is lambda correction but only under partial load. At full load it is all based on the pre-set mapping.

I would not change the injectors unless i had means to correct the mapping. There is nothing to be gained by changing only the injectors, IMHO


It's like buying different running shoes would make you run any faster. Or like buying a set of fresh tires with a VMax of 220mph would raise your cars top speed...

HiWind

been working on this option for a while ... ended up finding the greens (440cc) for a great price from a local who bought wrong for his application ...

very useful website as I had a lot of trouble sourcing the flow rates, resistances and BOSCH part numbers (pn) for the porsche parts. The OPC 550 993 TT injectors were 2.5x the price.

my 3.8 runs indep fuel mgmt and we were maxing the stock 193 injectors out so this shd help alot.
Thanks to Colin and the OP for the info above! I chose the green monsters (p/n 0 280 155 968)

Independant LIST OF FUEL INJECTORS, FLOW RATES, PART NUMBERS

The flow rates shown are at 100% duty cycle (static) and are for gasoline.
Although we do show some rating pressure most injectors are designed to operate 36.25 PSI / 2.5 BAR or 43.5 PSI / 3 BAR - Chrysler and Porsche some times use 55 PSI / 3.7 BAR
Remember this is a pressure differential across the injector, this becomes important in Turbo/Supercharged (SC) engines, where you need to use a regulator that increases fuel pressure as boost increases.
Injectors are rated at "X" psi, but most will work and flow more fuel at a higher pressure.
There is a calculator on my Home Page to convert flow numbers from one fuel pressure differential to another.
Fuel pump flow decreases as the pressure goes higher, so make sure your fuel pump has enough flow at the pressure you raise it to.
Estimated Horsepower figures are calculated at 80% duty cycle and 95% duty cycle also based on BSFC (Brake Specific Fuel Consumption).

backitoff

I noticed Colin mentioned the paper air filter and lid being the biggest restriction. What is the best options on this?

HiWind

I'm using a K&N re-oilable one ... but found no measurable difference on dyno with/without the airbox cover
possibly due to hot air getting in more easily .. the paper filters maybe safer though ie less likly to let thru grit ... a few bits in the oily surface inside my intake reminded me of this recently.