Nissan Fuel Rails

Geoff Knight mentioned that fuel rails from the Nissan SR20DE engine used the same injector spacing as the KL engine, and that it was also a side-feed design. Two rails would be needed, since the SR20DE is a 4-cylinder engine, but otherwise it could be made to work. Geoff also sells KL fuel rails modified to accept the Nissan injectors for $150/set (with exchange of old rails). According to the August 2000 Turbo magazine, the SR20DE engine was used on

For reference, the stock injectors for the Mazda KL engine are rated at 220cc/min. The Mazda factory service manual gives 192-224cc/min as the acceptable range when testing the injector delivery rates. We have one report of the injectors flowing an average of 230cc/min after being serviced (cleaned and balanced) by RCEngineering.

The Nissan injectors (that we know about) come in 3 variants: black top @ 285cc/min, pink @ 325cc/min, and red @ 375cc/min. This gives a nice range of choices for modified KL engines of various degrees.

Joe Kamman has actually started to install these rails on his PGT. Here are some photos of the preliminary install. At this point the rails still need to have the hose fittings attached (brazed). The rails pictured here are from an SR20DE. The original mounting tabs were machined off, and custom universal clamps are used to secure the rails.

Joe has been doing all the work and providing info on in the Forced Induction forum. I'm just summarizing the information and providing web space for these images.

Photos of the unmodified Nissan rails and injectors, in a PowerPoint slideshow

The view from the underside of the intake manifold, with rails mounted: JPEG image
As above, different angle. Notice the clamp on mounting point #4. JPEG image
A look at the end of the rails. These are unfinished, they still need hose barb fittings to be attached. JPEG image
Another underside shot. JPEG image
An underside shot, with the complete manifold in view. JPEG image
The custom clamps, an injector, hose fitting, miscellaneous hardware. The washers are used to adjust the height of the clamps so that they can be used with either the Nissan or the stock Mazda rails. Very slick. JPEG image
A long view down the end, with an injector installed. Gives you an idea of the clearances involved. JPEG image
Another end view, no injector in place. Shows the mounting hardware. JPEG image
An overhead view of the mounting hardware. JPEG image
An overhead view of the mounting hardware. (Similar to previous shot) JPEG image
A closeup of the injector and the 4-piece connectors. JPEG image

Other notes... The stock Mazda rails have identical spacing of 97.4mm between all injectors (center to center). The Nissan rails have a lot of variance, but are close enough to still seal properly. (1-2, 3-4 is 97.75mm, 2-3 is 96.4mm. The Altima rail looks identical to the SR20 rail, but the measured spacing was 1-2, 3-4 @ 95.9mm, 2-3 @ 98mm. It's probably still close enough to work.)

Despite the uncertainties involved, this is a very attractive upgrade path for modified KL engines that have higher fuel requirements. The only other alternative is to buy Venom high flow injectors at around $150 each. Used Nissan injectors go for only $15 each, and they have a pintle-less design which is very clog-resistant. In general, these used injectors should be very reliable.

Of course you still have to solve the problem of getting the engine control computer (ECU) to behave properly with these higher flow injectors, but that's a story for another day...

I will try to keep this page up to date with notes on this mod, but if you want up to date info you should just go over to ProbeTalk and follow the discussion there.
-- Howard Chu 2001-06-16