My GPRXP build

[John's truck]

So I just ordered some goodies. Everything I’ve read on GreenHulk says the RXPX 255 ECU (which I’m using) is mapped right so with 48 or 50 lb injectors and rising rate fuel pressure, it will be pretty spot-on for a ET137 wheel. So… I just bought a cheap 137 wheel, used stock 48 lb injectors and EV6 to EV1 injector connectors. I understand there are differences in injector dead times going from the Bosch Green giant 42’s to whatever the stock 48’s from the Bosch ECU skis are. I know it won’t be perfect and I’ll still be limited by the stock rev limit and timing. Which means the Yamaha boat prop is probably going back on, and we’ll see if we can get it up to 8000 rpm. I need to track down my extra McMastercarr spring washers to bring slip up to 15 lb, and I need to set up the fuel pressure for rising rate. I really didn’t want to run the Rochester/Riva 50 lb injectors I have now since they’re notorious for locking up at like 62 psi and I’m planning on base pressure of 58+ 13 to 15 psi on top. That’s danger zone for the 50’s. I think the 48’s will be fine.

And, if this setup pisses me off too much, I’ll go to a stand alone and just tune the damn thing for real, raise the rev limit to 9000 and spin the Dynafly as high as it wants to go. I was already planning on running this same supercharger and boost referenced fuel pressure to keep a 58 psi differential across the injectors. So this won’t be unneeded steps. I’ll keep using this stuff in the future. Maybe with different injectors but that’s easy enough to swap out.

Also, I am already monitoring AFR’s, just checking them visually as I ride. I can’t log them.

[John's truck]

Little more on that. I bought a used fuel rail with injectors. It’s from a 2012 GTX 215, but the injectors are the same as the RXPX 260. They’re the Deka long tip 8 hole 48’s which I guess all iControl skis used. Since they’re used, I’m going to need to flush and Test them. I’m thinking I have an easy solution. They’re already mounted in fuel rail. I can just fill the rail and inlet hose with WD40 or PB blaster or something, pressurize the hose with 60 psi air pressure, and then give each injector 12v so it sprays in to a bucket. I’ll run a good amount through it and then move to the next one. Obviously this won’t be a scientific test, but it should show if they’re clogged/leaking/dripping and show spray pattern.

Kinda ironic though. Siemens ECU skis used Bosch injectors. Bosch ECU skis used Siemens (Deka) injectors. What’s Next, dogs playing with cats?

[John's truck]

So the next think I need to address is the boost reference hose. I know that Rising rate used to be common in the tuning world you get increased fuel pressure up top and better idle. But then it fell out of favor once large injectors with short minimum on time came on scene and ECU’s could idle them without having to reduce fuel pressure. Rising rate was viewed as an old school way of maxing out injectors by cranking up fuel pressure.

But there’s still the other aspect of it. A boost reference fuel pressure system maintains the set pressure differential across the injectors. There will be 58 psi across the injector under vacuum, cruising, and at WOT. At 15 psi of supercharger boost, I won’t have 58 psi fuel minus 15 psi in the manifold so 43 psi differential and now the injector flow rate is reduced significantly.

But anyways, I need to decide where to drill for the boost reference hose. I’m using an older throttle body without the fogging nipple. And I don’t really like the idea of drilling the intake manifold barbs for the line. I did that for the boost gauge and I don’t like it. So I’ll probably drill and tap the front circular plate on the manifold to 1/8 NPT and use push-lock fittings for nylon tubing.

[John's truck]

Well I just ordered 10 feet of poly pneumatic 1/4” tubing, and a pair of 1/4 push lock 1/8 NPT fittings. So I’ll put one on the FPR and one in the manifold like this:

[beerdart]

1/4"OD may not signal well I went with 5/32" and it worked well. I can supply you with some.

Well I just ordered 10 feet of poly pneumatic 1/4” tubing, and a pair of 1/4 push lock 1/8 NPT fittings. So I’ll put one on the FPR and one in the manifold like this:

[John's truck]

1/4"OD may not signal well I went with 5/32" and it worked well. I can supply you with some.

Well crap. I just went looking and sure enough. Straight from Aeromotive. I’m gonna give the 1/4 a try but I’ll keep it in mind that I might have to downsize my reference line



https://aeromotiveinc.com/wp-content...c_Boost_01.pdf

[John's truck]

So the injectors and rail arrived. I can start mocking up my flushing setup. I’m thinking about just using compressed air to blast something like B12 injector solvent through them in to a pickle jar (clear, so I can see the flow) and obviously a gallon because I like pickles.

But, the injector adapters I ordered won’t work. Because I assumed they were EV6/EV14 us car whatever. They aren’t. They’re Nippo Denso Honda/Nissan. So now I need to order some more stuff to make this work. Im keeping my EV adapters in case I want to run some ID1000 or Bosch style in the future.




this is what I need. Denso to EV1

[John's truck]

Gonna take one to Lowe’s tomorrow and get some fittings to make my pickle jar pressure test rig

[John's truck]

Oh and just to get it out in the air and dispel a myth/bad info I keep reading on this site, these injectors (2012, Bosch ECU) are high impedance. So are the injectors from the 2008, Siemens ECU ski. All SeaDoo injectors are high impedance. I keep seeing certain injectors being sold for Siemens ECU skis and other injectors sold for Bosch ECU skis. It has nothing to do with impedance. It’s because whoever wrote the tune wrote it around the dwell time and flow rates of a certain injector and doesn’t want to re-write it. You can use VT1100’s on your 2005 and Deka 60’s on a 2023, as long as you have a tune written for it.

No, I don’t have a tune written for these injectors. I’m just winging it.

[John's truck]

Harnesses showed up. Clipped right in. So 2012 icontrol 215’s use NippoDenso injector connectors, not EV6/14. When I ordered these, I thought they were in wire loom. I guess not.