Fuel delivery questions for custom setups.
 

I am starting my 5th injector install.. This is going to be a 12 Volt injector from a Saab.

I need some ideas on the fuel delivery, which I haven't decided on yet.


I wanted to run a WOT switch that will apply power to the 12 Volt injector. I was thinking about using a in line type fuel pump that will also turn on @ WOT from the same switch.

This all is going to help delivery my shot of nitrous that will be mixed with the gas @ the 5th Injector. All controlled with this WOT switch. So all come on line at same time..


My questions are. Where would YOU get the fuel from for the secondary pump?

Tee off from current lines?

Pull the fuel from the return line to the tank?

The reason I chose a complete secondary system, is cheaper and easier to diagnois if I have problems, and make it more reliable being all of this is operated with a switch and the stock system will be untouched.

If you had the pump turn on when you have the injector turn on, then wouldn't there be a lack of pressure in that fuel line for a short period?

I doubt it, maybe a nano second or so..but that won't matter as it also take a nano second for the nitrous to get to the injector also.. so yes it may blow, but not too likely.

Seeing the stock system is good for 275 hp.. a nano second of nitrous won't hurt anything till the fuel is there right behind it...not only that but it requires fuel pressure to inject the fuel into the engine, so it should very safe

Why not run a dual feed nozzle for the Nitrous and Fuel?

explain? Is that a injector? Or a connection?

http://www.holley.com/HiOctn/ProdLin...A/FogNozl.html



http://www.holley.com/HiOctn/ProdLin...SprtmnFog.html

Thanks I understand now..


Any ideas on where I should get my fuel from and how to do it?

I would run a second pump to be safe

I went with the walbro for this exact reason. I can tap my fuel rail at any point and not worry about pressure drop from too much volume.

A dual pump sounds like more work than its worth to run a little injector. The 5th injector sounds like more work than its worth too. They have solenoid kits and jetted inlet nozzles for this exact reason. They've already taken all the guess work out of it for you. Piecing together a kit is much more cost effective than trying to re-invent the wheel in this case.

The lacking of fuel to back up your nitrous for a nano second is more than enough time to burn holes in things and detonate apex seals. What happens when that rinkydink patchwork fuel pump doesn't pump? Or even worse... You go to fire this contraption off and the injector fails?

Where are you getting this 275hp stock fuel system figure from? Running the stock 460's at 100% (which your stock ecu will NOT do) still only works out to 265.1hp. fuel calculator

Based on popular belief that the stock ecu will run them near 80% you're left with 212.1 flywheel HP.

Granted this fuel calculator makes no consideration for A/F ratios which will greatly affect its determinations. it is safe to assume that running nitrous you'll want to be richer than leaner to prevent too much heat in the combustion chamber and melted engine parts.


If you're dead set on this contraption, I would personally add the fuel before the extra oxygen. (which is all nitrousoxide is used for) And some kind of line pressure cut off switch in the fuel system.

Not trying to flame you here in the least. I just get a bad feeling when you start saying unregulated fuel delivery and toggle switches with nitrous.

I would go with a bigger fuel pump and a secondary injector holder just like an FD setup. An HKS injector controller would be a very wise thing to get also so you can control it for whenever. -Gabe

With an NA I would think a walbro would be good enough to run all 5 injectors. Thats my opinion though. The walbro is much better than a TII pump even so its pushes alot more than an NA one.

But I think the larger pump makes you run too rich at idle, not sure..exactly..


This little setup, I have seen it on 2 other cars, but they used a Hobbs pressure switch to turn on the 5th injector. But thats just one more part to fail, and not really needed.

Maybe I can wired in a Zener Diode to cut the voltage down to the nitrous, until the fuel pump is 100% online and I have good pressure @ the Pintle.

This is not going to be a hacked up project.. No way..I am going to take my time and do it right, and being a standalone system, I only have to use when I need to...Big Block V-8s....:D

S-afc... down 5% at 1K and lower and 4% across the board from there up with the walbro.

Essentially an injector is a directed, flow controlled solenoid. I just think its asking for trouble to use one based on a couple characteristics of them. 1st, they are fuel pressure dependant for volume of flow. 2nd, they are an electromagnet controlled device which loses its ability to perform its job when it heats up. (the needle closes as the magnet weakens)

More common nozzle and solenoid valve assemblies are also pressure dependant for volume of flow, but they are less likely to become restricted from contaminants in the fuel and lose their effectiveness or leak from such deposits on the valve assembly.