Dash01

Internet search and discussion with local car parts places found several suggestions for direct replacement of the stock Bosch 0 280 150 803 injector, also known as Porsche part no. 951 60611000. That is what came on the car from Germany, apparently. It is said to be low impedence, peak & hold activation, with ~36 lb. flow rate @ 2.5 bar pressure.

Bosch/Ford injector E5ZE A3A multiport injectors reportedly have compatible impedence and similar flow rates, and are said by the distributor to be better than the stock units. These are advertised for as little as ~$25 apiece.

"Standard" brand multiport injectors FJ416 are said by one local auto parts house to cross-reference as a direct replacement for the stock Bosch unit. ~$75 quoted price.

Multec injectors for GM quad 4 engines are claimed (by one internet poster from several years ago) to work in his 951. However, he could not be contacted for follow-up confirmation. No specific price mentioned, but said to be much cheaper than stock

Supposedly, each of these alternate injectors will work without further modification of the car, i.e., no extra chips, balasts, etc.

OTOH, at least one respected 951 guru (Markus Blazzak) has told me the ONLY suitable replacement is the stock Bosch 0 280 150 803 injector. Quoted price ~$95-100 apiece.

So, the search for accurate and verifiable information continues.

Does anybody out there have direct, personal, successful, long-term experience with an alternate injector? (That is, without having to use extra chips, ballasts, etc..) If so, please post your experience here, along with prices and sources of such injectors. I'd like to find a simple, safe, reliable, modern, & efficient replacement for old the stock injectors.

FWIW, the Bimmer 5 Series guys have found significantly better performance and economy by going to a more recent injector, so I'm hoping someone has found similar ugraded injectors for the Porsche 951.

Danno

Hmmm... there are zero direct replacements for the stock 951 injectors. That's because they have a bizarre 5.5-ohm impedance. You will not find another injector with that specification.

"FWIW, the Bimmer 5 Series guys have found significantly better performance and economy by going to a more recent injector,"

I'm not sure how this is possible unless the original injectors were not optimally programmed with appropriate air-fuel ratios in the EFI system. For example, if the mixtures were way too rich across the board at 10.0:1, the car will be sluggish and fuel-economy would suck. Then going with slightly smaller injectors or injectors with slower response times would lean out the mixture to12.0:1 and you'd pick up 15-20% more torque and HP. But the problem here is improper programming, not poor-performing injectors.

FWIW, I've tried stock 34.6-lb/hr injectors all the way to 96-lb/hr with the exact same configuration in my 951 to isolate performance differences to injectors only. This required scaling back the duty-cycle in proportion to the difference in injector sizes in order to inject the same amount of fuel. The results were identical performance (HP/TQ, area under curve) figures. The only difference was that when the stock injectors were operating at 100% duty-cycle, the 96-lb/hr ones were only at 36%.

Another way to look at this is to imagine you were inside the combustion chamber itself, like the tip of the spark-plug. In which case, you have no idea what mechanism delivered the fuel, be it injectors, carbs, passive-vaporization (DeDion), etc. As long as the same amount of fuel made it into the chambers and the spark was set off at the time, the power-output will be exactly the same.

mmm951

I replaced the injectors in my BMW 635csi with a set of Mustang injectors and did not get any better performance or fuel economy. I got them because they had the same flow rate/imped. and were a fraction of the price. I am afraid Danno is right - they don't make a replacement for the 0 280 150 803 injector. You might be better off pulling them and getting them cleaned.

Good Luck

Dash01

That's interesting, because several BMW E34 guys (535i drivers in particular, on the Bimmer Forums website) have reported getting ~1.5 extra miles per gallon by going to the newer injectors. Granted, the improvement may well be at least partly due to using clean new injectors instead of dirty old ones.

These Bosch/Ford Design III injectors have a rotary disk that sprays the fuel in finer droplets over a wider area for better atomization. Works like a rotary lawn sprinkler.

Further, the stock Bosch -803 injector in our Porsche 951 cars is the old (obsolete?) pintel type, which is out of favor because it is more prone to clogging or performance degradation than newer multiport injectors.

That is one of the reasons I'm hoping to find information from other stock 951 drivers who've actually tried different injectors.

OriginalSterm

The Bosch/Ford injectors probably have a USCAR connector on them. You will need an adapter since the harness is for a different injector connector I believe.

As far as pintle designs being obsolete, that is bunk. They (as well as everyone else) is still using pintle style injectors. The director plate on the tip is designed for a certain spray pattern and are not necessarily interchangable between applications. Also, larger holes yield higher static flow rates (typically) but also larger particles which are more difficult to atomize and burn. What you want is the smallest particles possible with the best (most even) spray distribution and the appropriate cone angle.

As far as new injectors being "better", that could be for several reasons. Like mentioned before, the old injectors could have just needed a cleaning. The new injectors may have a better opening and closing response which gives a longer duration of finer particles with the proper spray characteristics during each pulse. The new injectors may also have better, more even distribution of fuel due to a better director design (or manufacturing process, ie EDM vs. stamped).

mmm951

Eric,

My car actually had a better idle and might have gotten better mileage (slight amount). I think it was die to the fact that my injectors were dirty and not atomizing the fuel properly. As far as the injectors providing higher perf., I am not so sure.

Michel

toddk911

I bought injectors form the DSM models (Mid-late 1990's Turbo Eclips/Talon) 450cc Low Imp. peak/hold used and flow tested.

$110 shipped!! Which came with the fuel rail that I will resell on ebay

You can also get them on ebay pretty cheap.

toddk911

Danno is gonna burn chips for them and I can use the 550cc setting, but will be tuned for 450cc.

Dash01

Is it possible to get say some 680cc injectors if I buy some guru racing chips?
On the guru racing site it says price at $295, but will it be more due to the special aspects of the injectors?

Dash01

Another question:
How do the injectors rated in cc's compare to injectors rated in lb/hr?