GLHS

I plan on using 2 extra injectors on my N/A. These will be cold start injectors and only run, when WOT.

Should I run a second fuel pump for these injectors, or use existing fuel pressure and run extra lines?


This is for my custom setup, I am building and should get really interesting right around the time I add the 250 shot of nitrous.

CrackHeadMel

iTrader: (2)

How are you going to control these extra injectors?

Id re-do the entrire fuel system and make it like ReTed's parallel fuel system only with an additional rail

a 250shot of nitous? isnt that a bit much for a rotary?
i dont know how long your drivetrain would last with you doing that

-Jacob

Roundabout

iTrader: (8)

Pop goes the motor!!

GLHS

Nitrous will be fine for the engine, as long as I have enough fuel.

I have seen this done before, the only problem is you have to change the oil after a heavy use of Nitrous.

So I may fabricate a sump for the spent oil, so it only goes through the engine once.

The fuel will be controlled by a switch on a fuel pump that is connected to the signal of the Nitrous, once the switch is tripped @ WOT the Nitrous and fuel will start to flow together, anytime I press the pedal to the floor.

I am now getting a switch that will bolt to the throttle body and activate once it hits WOT.

rx7_turbo2

You explained how the fuel pump will turn on but you never addressed the injectors. How will you make the injectors fire? Personally I think this is pretty stupid. Why not go turbo and do it right?

DaleClark

iTrader: (55)

The extra injectors isn't the way to go - you need a wet nitrous system that injects fuel and nitrous. You *have* to be able to tune the fuel to go with the nitrous, and ancient cold start injectors from the junkyard are NOT the way to go.

Wet systems have pills for the fuel just like the nitrous pills to tune the amount of fuel for the nitrous. You will definitely need an upgraded fuel pump for the amount of power you're looking to run. Not to mention a clutch and probably a spare tranny .

Dale

GLHS

don't worry fellows, this setup will not be used while shifting, it is totally dependant on WOT.

I understand about changing the orfice sizes of the fuel and Nitrous, and tuning with EGT and A/F should run for quite a while, I suppose.

As I understand it the stock N/A injectors can handle up to 275 hp without any problems. Upgraded fuel pump may put the injector past their maximum duty cycles.

I ran 75 shot before and it really cooled the engine down while in use, with more fuel, should be even better.

Plus I can get trannys and engines for $75. It helps to know people, who have done this before.

rx7_turbo2

I don't think that's correct.

GLHS

I should be able to get signal from the current primary harness.

Since when is turbo considered the right way to make power?


would you want to run a 450 hp N/A RX7?

Piranha

Tuning with an A/F gauge? good luck... my A/F gauge never goes above .6v, even when I popped my engine, and now, with a rebuild, I throw massive fireballs and it STILL shows .6v. Only time it doesn't is on the open (or is it closed? loop) and engine braking.

GLHS

use your A/F with the EGT and you can monitor a car perfectly.

rx7_turbo2

I thought you said the additional injectors would only fire under wide open throttle? If your using the signal from the primarys would they not fire all the time then?

I don't know this sounds like a real hack job to me.

GLHS

why yes it is going to be a custom setup, not just a system purchased off the shelf.


Just cause the injectors see voltage, doesn't mean they deliver gas, that happens once it hits WOT and the fuel pump kicks on and the nitrous starts flowing.

Piranha

what is going to cool the injectors? Just dry running them should be bad...

rx7_turbo2

So your injectors will be firing dry, and firing constantly? Like I said hack job.

GLHS

These are small minor things that can be overcome.


I also enjoy hack jobs, if they work good and are cheap enough.

DaleClark

iTrader: (55)

Uh, when you run a wet nitrous shot, you're injecting both nitrous and the appropriate amount of fuel to go with it. Extra fuel = you don't need any more.

There's no good reason to run the cold start injectors. Hell, there's *never* a good reason to run cold start injectors .

Dale

GLHS

now this is something I don't understand.

why is "cold start injectors" bad?


I am part of a very large TD car club and everyone uses these cold start injectors, and get very good results from a $15 injector and pressure switch, that controls the injectors. However these are setup to turn on when a certain amount of boost is achieved.

scathcart

I have more experience with big nitrous shots than anyone else here in the second gen forum.

You're thinking for this is all wrong. You should PM me or email me.

DaleClark

iTrader: (55)

Cold start injectors are either on or off - there's no resolution to them. So, you get hit-or-miss AF ratios with no ability to tune for air mass, RPM, whatever.

Yeah, they'll put more fuel into the motor, but quality is as important as quality.

I'm assuming TD is Turbo Dodge. These guys are about doing things with ZERO budget - who cares how it looks, sounds, or runs, just as long as it's fast. I have a lot of respect for those guys and the work they've done, but a lot of their solutions are far from elegant and are only really suited to a run on the drag strip, not real-world driving.

Dale

scathcart

For a shot that big, you would want a wet system, which feeds the nitrous oxide and and fuel into the engine in a fog, mixed together. The benefit to this is it doesn't use the stock injectors, which would be pretty maxed way before that level of horsepower.

Adding a fuel pump provides more flow to the rails, but does not increase fuel rail pressure. Pressure is regulated by a bleed-off valve known as the fuel pressure regulator, which sends enough gasoline to maintain rail pressure back to the tank. The more fuel used by the engine, the less fuel sent back to the tank. Adding a bigger fuel pump does not increase the injector duty cycles.

A wet system plumbs into the fuel rail. The fuel is taken via a hose to your nitrous foggers. The provided your pump is big enough to save from a drop in rail pressure, your engine will be fine ***.

Using wet nitrous keeps engine fueling separate. Adding additional injectors is unnecessary. Adding more fuel with injectors would be a waste of time. Perhaps you are thinking of a dry set-up, where the extra fuel to compensate for the nitrous is added via injectors? 250 hp shot is too big for a dry shot. You will destroy your motor.

And we haven't even begun with drivetrain...

Read this article I wrote;
http://www.1300cc.com/howto/how2/NOS.htm

and then PLEASE get back to me. I don't want you to blow your motor, and give nitrous yet another black mark.

DaleClark

iTrader: (55)

Well....*kinda*...

In theory, a higher flow fuel pump shouldn't affect fuel pressure at all. You just have more volume to maintain pressure. The problem is the stock FPR is designed around the stock fuel pump, and higher volume fuel pumps put out too much flow for the stock FPR to handle. It's like having a kink in a garden hose hooked up to a water spigot - you maintain pressure with that kink in the hose. Hook it up instead to a fire hydrant, and the hose will probably burst from pressure . Silly example, but you get the idea.

The best route is using an adjustable fuel pressure regulator that can maintain a 1:1 ratio - you can set the base rate of fuel pressure. I had to do that with my re-wired Walbro fuel pump.

But, this is only in some circumstances - it really depends on the pump and the system. I was having problems running way rich, so I had to use the adjustable FPR to tune it down.

Anyhow, your mileage may vary, just some thoughts .

Dale

rotarygod

iTrader: (1)

scathcart how the hell are you running 280 shot of NOS? I don't care if it is in 2 stages. NO rotary can handle that much. Well maybe once. Maybe....... if it was specifically built for it...well maybe... NOS is MUCH harder on the engine especially the apex seals than compressed air from a turbo. I can see using about 125 shot MAX on a rotary and even then only ocassionally. If I could afford to build an engine every other day I'd run a 200+ shot.

Hell yes I'd race against a 450 hp n/a RX-7. I'd do it in my 127 hp Civic. I wouldn't even pull out one of my RX's for that race. When he shifts into 2nd gear and the magic white genie apears from under the hood I'll fly past him. Hell I'll ride my skateboard!!!

No amount of concvincing or arguing can or will EVER convince me you can run that much nitrous in a 13B so please don't try.

scathcart

I agree, I mentioned it in my nitrous write-up. Just didn't bring it up here. This guy is confused enough.

scathcart

OK.