Nitrous on 2.5 Drag

[CI STV]

What I’ve done successfully is use the motor fuel injectors hit a button and pick the amount of richness I want. No, second pump no methanol no extra lines nothing, just nitrous.

I run a very small battery. I tried running a big weldon pump, which is more than enough for anything, but it drained the battery. I just tried the weldon pump for fun.

I’ve never tried this, but if you’re running a 56 pound regulator, you might be able to put a restrictive orifice in the return line. Perhaps that would give you the pressure you need. You might be able to use a solenoid in conjunction with nitrous activation to reduce the fuel through the return line momentarily.

Make sure you have your Pyro’s and fuel pressure gauges visible on the dash.

Are you saying that you were running a dry shot and adding fuel for the nitrous through the injectors?

I’m running a full sized blue top optima, but might change that out for a lightweight battery at some point, although i already tried running an expensive XS lithium and the POS came apart on my first outing.

I have an Aeromotive adjustable regulator, so I can increase the pressure all the way up to 75psi, although I don’t want to do that since the fuel jetting is for 55psi and I have the pressure set at 56.

I just changed out the fuel pump, although I’m not sure there was anything wrong with the pump.

I have the AiM dash programmed to flash red and show “LOW FUEL PRESS” if the fuel pressure drops below 53 psi (which it did) and I have a similar warning set for the EGTs exceeding 1175 degrees, which it never has.

I’m anxious to get back to testing it now.

[CI STV]

Methanol is the way to go. Just sayin'.

I know that’s what everyone says, but I’m not sure why I would need that for a 100-150 shot of nitrous though, especially if I’m using 112 octane race gas. I’m not even sure what that does for performance.

I get it that in the old Nitrox systems, the advantage with methanol was that you could keep the fuel solenoid open for a bit longer to cool down the motor after a nitrous pass. But at this hp level, running nitrous for ~8 seconds in an 800’ drag race, I’m not sure there’s any advantage for me.

The problem with running methanol for me is that I would need to source methanol, which I’m sure I could, but then I would definitely need a standalone fuel system (separate tank, pump, regulator, filters, etc.) and I would have to change out the fuel solenoid and re-jet the system for methanol.

[Stoker boy]

Why not pull the fuel directly from the fuel pump with a Y in the line? I’m guessing the fuel line would go to a metering block that goes to the six injectors?

[CI STV]

Why not pull the fuel directly from the fuel pump with a Y in the line? I’m guessing the fuel line would go to a metering block that goes to the six injectors?

That’s along the lines of what I wanted to do. I was going to use a -8AN Tee fitting to install in the line just before it goes into the fuel rail, to create a bypass to the fuel rail for the fuel going to the nitrous solenoid.

But when I tried to install it, I found out there’s not enough room between the fitting at the bottom of rail and the hump in the lower pan to make that work.

Here’s a picture of what I’m talking about. The red circle shows the hump that prevented me from installing the Tee fitting. If necessary, I could also cut the fuel line in the area shown by the yellow arrow and install a Tee there.

I’m going to try it now with the new pump and the high flow fitting at the bottom of the rail and see if I still have a fuel pressure drop. I should be able to test it this weekend. I’ll get it sorted one way or the other.

[Stoker boy]

[Stoker boy]

You can put solenoids in the area above your horn or SVS where I have my pressure regulator. This photo does not have a nitrous set up, but I have put four solenoids in the area where the pressure regulator is.

[Stoker boy]

[Stoker boy]

Why not pull the fuel directly from the fuel pump with a Y in the line?

[Stoker boy]

I’m guessing your fuel pump is mounted to the transom or knee braces. I would take a Y from that point on the outlet, run a separate hose to the fuel solenoid.

Personally, I would stay away from the regulator trying to supply fuel to my fuel solenoid.

Is your pressure drop when you’re running the motor or does it drop when you hit the fuel solenoid?
are you running 56 psi?

[Stoker boy]

Are you saying that you were running a dry shot and adding fuel for the nitrous through the injectors?

I’m running a full sized blue top optima, but might change that out for a lightweight battery at some point, although i already tried running an expensive XS lithium and the POS came apart on my first outing.

I have an Aeromotive adjustable regulator, so I can increase the pressure all the way up to 75psi, although I don’t want to do that since the fuel jetting is for 55psi and I have the pressure set at 56.

I just changed out the fuel pump, although I’m not sure there was anything wrong with the pump.

I have the AiM dash programmed to flash red and show “LOW FUEL PRESS” if the fuel pressure drops below 53 psi (which it did) and I have a similar warning set for the EGTs exceeding 1175 degrees, which it never has.

I’m anxious to get back to testing it now.

That’s correct, I run the system dry and increase the fuel curve through the fuel injectors.
I’ve only done that with the 100 shot not the 175. From the dash, I can quickly adjust the fuel curve to where it will flood out the motor.

I’ve been playing with Nitrous for 30 years. This is something I tried a few years back, but I haven’t been able to mess with the boat a whole lot lately. Since I’m retired, I’m gonna start playing with the boat again.

For many years, I ran the nitrous with methanol as an enrichment fuel. I always use a bottle heater blanket. Everything worked great.

[Stoker boy]

I know that’s what everyone says, but I’m not sure why I would need that for a 100-150 shot of nitrous though, especially if I’m using 112 octane race gas. I’m not even sure what that does for performance.

I get it that in the old Nitrox systems, the advantage with methanol was that you could keep the fuel solenoid open for a bit longer to cool down the motor after a nitrous pass. But at this hp level, running nitrous for ~8 seconds in an 800’ drag race, I’m not sure there’s any advantage for me.

The problem with running methanol for me is that I would need to source methanol, which I’m sure I could, but then I would definitely need a standalone fuel system (separate tank, pump, regulator, filters, etc.) and I would have to change out the fuel solenoid and re-jet the system for methanol.

112 octane is an advantage when you’re running high compression. What compression are you running. A stock drag motor with 26 cc heads is somewhere in the 175 to 180 cranking compression.

At that compression you’re safe to run something like 102 103 octane you can obtain that by mixing pump premium and race fuel.

Running that high of octane is really only an advantage when you’re running very high compression.
Are you running gasket heads or O-ring heads.

You keep an eye on your Pyro’s. If they get hot after the past, you can just enrich the motor injectors to cool your motor down.

[CI STV]

Why not pull the fuel directly from the fuel pump with a Y in the line?

I could do that, but I don’t see the need for it.
I could just as easily do a Y or a Tee inside the engine cover, IF that’s even necessary. The pump has a single -8AN outlet, and I know a single -8AN fuel line can deliver way more fuel than I’ll ever need at 56 psi.
Even those Aeromotive compact regulators can provide enough fuel for 1,000 hp. So IF there is in fact any restriction left between the pump and the fuel solenoid, it’s probably the fuel rail, so the best thing to do would be to bypass that.

[CI STV]

I’m guessing your fuel pump is mounted to the transom or knee braces. I would take a Y from that point on the outlet, run a separate hose to the fuel solenoid.

Personally, I would stay away from the regulator trying to supply fuel to my fuel solenoid.

Is your pressure drop when you’re running the motor or does it drop when you hit the fuel solenoid?
are you running 56 psi?

My pump is mounted about a foot behind and below the tank. It has a 10AN inlet with a 100 micron stainless steel screen filter between the tank and pump, and a 8AN outlet with a 8AN line running through a 10 micron “Microglass” filter to the bottom of the rail. I had a short, sharp radius 90 degree fitting on the bottom of the rail and I think that could have been a bit of a restriction.

Those regulators work fine with the ports on the side working as an inlet and outlet. I have one just like it on my Vette providing fuel regulation into the injector rail from a Holley Dominator twin pump, and it works flawlessly, and I’m running a supercharger and nitrous on that.

[Stoker boy]

Sounds like you got it covered, I’m sure you’ll work your way through it. Good luck, stay safe.

[CI STV]

That’s correct, I run the system dry and increase the fuel curve through the fuel injectors.
I’ve only done that with the 100 shot not the 175. From the dash, I can quickly adjust the fuel curve to where it will flood out the motor.

I’ve been playing with Nitrous for 30 years. This is something I tried a few years back, but I haven’t been able to mess with the boat a whole lot lately. Since I’m retired, I’m gonna start playing with the boat again.

For many years, I ran the nitrous with methanol as an enrichment fuel. I always use a bottle heater blanket. Everything worked great.

Nice! We’re running a dry 75hp shot on a friend’s Qmaster and it runs flawlessly. The temp sensor will read the nitrous as extremely cold weather and adjust the fueling accordingly. That’s actually why I relocated my sensor to outside of the manifold and put it on the solenoid bracket, since I’m running a wet system. The problem with the dry system is without having control of the additional fuel the ECU is providing, you have no way of knowing what the fuel to nitrous ratio is.

I’ve been playing with nitrous for over 30 years too, starting with my brother’s old Trans Am back in the late 80s. I’ve put nitrous on just about everything I’ve owned every since, other than heavy equipment, lol. I even had a Nitrox system that I bought from Chuck Goodman on my old Johnson looper that I had back in the 90s. That worked well but was dated technology even back then. The flowed and dyno tested nitrous systems they have now are way better than back then. I have a single plate system from IS on a race car I’m building which is rated at 640 hp, through a single nitrous jet! Back in the 90s, I thought getting 225hp out of a NOS Cheater system was impressive, lol.

Funny enough, although all the big nitrous companies offer special solenoids and jetting for methanol, I’ve never seen one recommend using methanol for additional horsepower or beyond a certain point, etc. That only seems to exist in the two-stroke outboard arena.

I use a heater blanket to get the bottle pressure around 950-100. Increasing pressure beyond that only throws the jetting off, IMV.