Who is running dry shot nitrous? Curious about it

[tf95ZR1]

Impressive.
Let us know how it performs.

[1991 Corvette ZR-1]

So the rpm readout is not correct at all. At idle, the readout is 3100 or so on the switch readout. At just 1500 rpm in first gear down the street resulted in 6,000 + rpm readout on the switch. Not good, obviously. So it does not appear I can use F cavity off the diagnostic plug for rpm signal. I did uncover a post over on LS1 tech in which the LS based engines required window switches to be set for a four cylinder to read correct rpm. I tried switching from 8 to 4 cylinders in the switch and no change to the readout.

Now this is where I throw myself under the bus. The instructions for this switch clearly states ? connect tach signal wire to ground side of a coil in a coil on plug or waste spark ignition system.? I am aware this is a waste spark system on the LT5. What I am not clear on is the ground for this system. looking at page 8A - 22 - 8 in the electrical diagnosis supplemental book and it is not jumping out at me. How is this ignition system grounded?

I see the G cavity on the diagnostic plug runs right off the coil tray. I doubt this is what I need. Any thoughts?

[1991 Corvette ZR-1]

I figured it out after playing with the switch settings some more. I tried the 4 cylinder setting and it changed nothing. In order to read the correct idle rpm, the switch wanted to see 8 cylinders and the ignition type set to distributor. Which makes no sense to me, as this is a waste spark system, but this corrected the issue.

[1991 Corvette ZR-1]

I am still dabbling in what I am calling more an exercise in boredom than application. I have not done much since outside of reading and research. I plumbed a 4 AN line from the interior outside and down the passenger side and installed a nitrous filter in line. Rest of the hoses are showing up to finish this part this week. I continue to be fascinated by the old Holley NOS kit 5172 and how its application worked. So much so that I called Holley to see if they had the old instructions archived for review.

Just my luck, after a while on hold, the gentleman told me they had the part number before 5172 and the kit after 5172 archived, but no 5172. It was a long shot, but no dice. Anyone know someone who may have a pdf of those old instructions? I was mainly curious about the fuel boosting option. I suppose that was my biggest worry even with potentially running such a small shot was the fueling needed. No magic way to pulse the injectors extra longer to accommodate the dry shot. Or maybe there is.

Someone posted a picture of a solution to this issue in an old nitrous thread but that picture has long since expired, so not entirely sure what they were referencing.

Edit - I originally intended to run this line on the driver side, however beneath the rocker cover is very crowded now with the new harness from the window switch and other wiring needed. Passenger side has plenty of empty space behind the rocker. I secured the line to the factory harness and fuel vapor line nice and tidy. I read some posts across forums on filter placement. Some stressed placing it as close to the bottle as possible, while some said placing it as close to the solenoid as possible. I consulted with Nitrous Outlet and they let me know its placement anywhere in the system would not hinder performance. And that works for me as I would like to conceal most of the hardware for a cleaner appearance inside and out.

[1991 Corvette ZR-1]

Picked up the PSN-1 nitrous gauge kit and started small stuff with it. In keeping with the desire to have the interior as clutter free as possible, I decided to mount the gauge in the vent. It is a portion that was not functional in the vent for airflow. This kit comes with a lot of stuff, so I will be busy for a while. Of primary interest was a two in one display which shows me AFR and bottle PSI at the same time. There is also a shift light built into it.

This thing is essentially a window switch with various kill switches built in, but I already have a window switch wired up, so I put the cart before horse on this purchase a little bit. Not sure I can integrate the AFR kill function to work with the circuit in place with the Nitrous Outlet window switch.

Eventually, I will have to have the bung added for the wideband sensor. I think I will be converting to a single pump fuel delivery system and run a Kenne Bell boost a pump set to trigger on when the system is armed. The boost a pump should then only energize off a vacuum signal reference of WOT when the system is armed. I dug through my pile of random nitrous parts I have had for years and found an adapter designed for an LT1 or 4 fuel rail. What do you know, looks like it will work on the LT5 as well. When I add new fuel injectors, the plan would be to remove the valve core in the schrader so I can use the adapter to install a fuel pressure safety shut off switch. That way if the PSI is not where it should be, the switch kills the nitrous. There is also a provision to add a new schrader valve so I can still monitor fuel pressure with a gauge.

So if everything goes as I am picturing it, I will have the dry shot with the added fuel from the boost a pump. Safety measures would be the window switch monitoring the WOT signal and 4-6K rpm only operation. Then the added layer of fuel PSI needing to be appropriate or it cuts off. I guess time will tell if I know what I am doing.

[HAWAIIZR-1]

Wow! This is cool and it sounds like you know what you are doing. Way back when I got my first Z in 2003, I want to run the so called safe, ZEX 75hp kit made for our cars. I did not have the balls to do it not knowing enough about nitrous. Cannot wait to see how your project turns out.

Image1662770711.867632.jpg


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[1991 Corvette ZR-1]

Originally Posted by HAWAIIZR-1

Wow! This is cool and it sounds like you know what you are doing. Way back when I got my first Z in 2003, I want to run the so called safe, ZEX 75hp kit made for our cars. I did not have the balls to do it not knowing enough about nitrous. Cannot wait to see how your project turns out.

Attachment 18585


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Thanks, Craig! Honestly, I flip flop on wanting to eventually run nitrous but I am enjoying the R&D part of making a custom kit. I would not say I am 100 percent on this. I am still hiding behind the excuse of doing this as an exercise in boredom. I figured someone might be interested in my process, even it has some setbacks on how I plan it out. I made an account over on an LS forum that has a decent nitrous section. I think I am going to do a little more research and ask a few questions as well over there.

And if anyone reading this knows and talks to Flyman 27 regularly, let him know I was trying to pick up one of his new stainless registers and racetronix pump plug n play kits assemblies.

[HAWAIIZR-1]

You are welcome. I am a sponge to learn anything I can from others. It just sounds like you are approaching it the right way and taking your time with research.

Yes, I will message Dan and show him your post to contact you. His stuff are awesome and very well thought out. I just upgraded the problematic doors switches too and his fuel assembly.


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[Flyman 27]

Originally Posted by 1991 Corvette ZR-1

And if anyone reading this knows and talks to Flyman 27 regularly, let him know I was trying to pick up one of his new stainless registers and racetronix pump plug n play kits assemblies.

Craig said you were looking for me.
I have pumps ready to ship.
If you can PM me I will give you payment info & you can give your shipping info.
Talk to you soon, Dan

[1991 Corvette ZR-1]

Originally Posted by Flyman 27

Craig said you were looking for me.
I have pumps ready to ship.
If you can PM me I will give you payment info & you can give your shipping info.
Talk to you soon, Dan

Thank you, sir! Craig does not mess around ha! PM sent your way, in the next week or two I will look to get purchase that register and pump assembly. I did not think I would get such a quick response.