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JSAautomotive

Not sure if I'm correct on this. Memory is kind of hazy. But when I worked for GM back in the 90's, I remember reading something about Disc vs. Pintle injectors, something about the long term reliability or suceptability to particular solvents in the fuel composition causing winding degridation??

I ran a set of disc style injectors in a customers Grand National and the idle quality was terrible. Tried saving money instead of buying the $140 a piece genuine GM units. Removed the disc units and installed the genuine GM injector and the car idled perfectly.

Any explanations??

Racetronix

Considering that the '009' 42# disc injector is the most popular injector for the Turbo Buicks we find you statement to be lacking merit. A simple search of www.turbobuick.com will provide plenty of hits on this topic. It is important that a chip be properly calibrated for size and type of injector as they all have different characteristics. Disc injectors are very fast compared to most older types if injectors. We also sell the 621020 as a stock replacement for the TR factory Bosch injector and they work fine with the factory chip. The internals of the disc injector are more resistant to all types of contamination when compared to a RP Multec injector or Bosch EV1 pintle injector. There are 1000's of people on this forum using disc injectors with great success.

JSAautomotive

I remember getting a bulletin from GM about fuel solvents and the degridation of the injector winding/coatings. Probably mostly concerning the faulty Multec units. Reed mean vapor problems in cold weather was the current talk at the time also.

I guess the diffuser on the Buick units allow the injector to "target" where they want the fuel. The Turbo Buick fuel metering system seems to want the fuel sprayed in a particular place in the port. The older style IAC motors are slow and cannot react to quick enough to atomization differences that a pintle or disc injector would cause, so once warmed up you end up with an idle roll, intermittant dying when placed in gear, or dying coming off the freeway offramp even with the minimum air setting set properly.

I've worked for GM for several years as a driveability tech and have seen a standard "pintle" style or disc replacement injector units cause idling problems on completely stock Buicks with no mods whatsoever.

Racetronix

This information is dated. Delphi even goes so far as to mention that their Multec 1 injectors are compatible with Methanol in some limited racing applications. This information is also listed in the MSD catalog. RP/Delphi Multec 1 injectors are not Delphi disc injectors, they are not made in the same factory nor do they share any of the same components. The Delphi/Lucas disc injector (Delphi bought out Lucas) does not have any issues with today's pump gas which is a chemical cocktail of various solvents as well as up to 10% ethanol.

The Buick's factory injector does not have a directed spray pattern that is unique. The factory Bosch injector produces a forward shooting fan spray pattern typical of pintle designs. Some injectors such as those used in older Dodge Caravans produce a pencil beam spray pattern which is shot off at an angle from the tip. These Siemens Deka 1 injectors are clocked in the intake manifold to ensure proper alignment with the air stream. We are unaware of any GM HP vehicle which uses this technique. All the injectors we have seen in GM HP vehicles produce a centered stream of fuel with varied spray patterns.

We have sold 1000's of disc injectors to the service industry w/o the problems you describe. Just last day we had a set installed in a '92 Buick Regal 3800. The engine ran silky smooth without any drivability quirks. The factory Bosch injectors were leaking down. Oddly enough the disc injector used provides a single pencil beam spray pattern vs. the Bosch's fan type spray pattern. This motor has over 200,000Km on it.

Since this forum and these injectors target the HP market your concerns do not apply. Anybody upgrading/upsizing their factory injectors will require a ECM/PCM recalibration which will address any fueling problems that may arise. There are thousands of disc injectors being used in HP applications today. Disc injectors are grabbing more and more market share every year. The only reason why Bosch pintle injectors are more common up until now is due to price and availability. The disc injector was many years ahead in design when it came out. It was faster and more reliable but as with any new technology people had trouble warming up to them. Many tuning issues that people had were mostly in part to the computer systems in the cars at the time. Today's computer's are much faster and more flexible. Today's new generation injectors such as the C5's Bosch EV6 are closer to the disc injector in speed which helps cross-compatibility issues. Many dealers such as A&A and Thunder Racing use 42# disc injectors with many of their HP packages with great success. People posting in this and other threads can also attest to their satisfaction with disc injectors first hand.

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THRLSKR

Just bought a set for my set-up - thanks!

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Coc5

Thanks for the technical discussion guys. I will be getting new injectors soon also.

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Racetronix
sales@racetronix.com
C4 Fuel Pump Systems, C5 Fuel Pump Systems, High Impedance Injectors > 60# F/M, 57# F/M, 50# F/M, 42#, 37#, 32#, 28#, 32#, 24#
Please check our web page for low impedance flow-matched injectors from Siemens and Delphi ranging from 55-95lb/hr.

Racetronix

ttt

Racetronix
sales@racetronix.com
C4 Fuel Pump Systems, C5 Fuel Pump Systems, High Impedance Injectors > 60# F/M, 57# F/M, 50# F/M, 42#, 37#, 32#, 28#, 32#, 24#
Please check our web page for low impedance flow-matched injectors from Siemens and Delphi ranging from 55-95lb/hr.

Racetronix

ttt

Racetronix
sales@racetronix.com
C4 Fuel Pump Systems, C5 Fuel Pump Systems, High Impedance Injectors > 60# F/M, 57# F/M, 50# F/M, 42#, 37#, 32#, 28#, 32#, 24#
Please check our web page for low impedance flow-matched injectors from Siemens and Delphi ranging from 55-95lb/hr.