Injector size

**89stang** · 08-04-2008, 10:32 AM

I am planning on running a dry kit on my 89 fox and am not sure what injector size to use. My mods are ported stock heads,1.6 roller rockers,trickflow stage 1 cam,cobra upper and lower intake,electric fan,fluydine red,msd, long tubes, h pipe, flowmasters. I have a 4 inch power pipe I will use with a mass air but not sure what size injectors or fuel pump to use. The nitrous wont be used all the time. Any one with some info will help. Thanks

**mike** · 08-04-2008, 10:57 AM

Did you purchase the N2O kit yet? Although many have successfully run the dry nozzle my experience has been that you have much more flexibility with the "wet" kit and eliminate any danger of running your injectors past their intended duty cycle. Also, a wet system will allow you to remove the injector requirements of a dry system from any future mods where more fuel from the injectors will be needed.

If you didn't purchase the kit yet, check out dynotunenitrous.com, great prices, fast shipping and we have been running/installing their systems for years with great results!

**Killercanary** · 08-04-2008, 11:16 AM

Question for Mike above...

Although I never have, and probably never will run nitrous I have always had the impression that a wet kit on a 5.0 mustang is a roll of the dice due to fuel puddling in the back of the intake and the increased risk of a nitrous backfire in the intake due to it. I've seen a few of these "bombs" over the years on the net and wondered how you avoid this situation? I know that plates and other such devices have become available to inject the nitrous/fuel mix into the lower intake, is that the only safe way to run a wet setup on a 5.0 mustang due to the upper intake plenum design?

**John4cam** · 08-04-2008, 11:35 AM

Originally Posted by 89stang

I am planning on running a dry kit on my 89 fox and am not sure what injector size to use. My mods are ported stock heads,1.6 roller rockers,trickflow stage 1 cam,cobra upper and lower intake,electric fan,fluydine red,msd, long tubes, h pipe, flowmasters. I have a 4 inch power pipe I will use with a mass air but not sure what size injectors or fuel pump to use. The nitrous wont be used all the time. Any one with some info will help. Thanks

From what I have seen on 5.0 liters in the past, 24 pound an hour inj. worked just fine for heads cam intake cars with nitrous, one in particular went low 11's on a 150hp hit with 24's. The fuel pump is a no brainer, 255lph all the way, you have a fuel return on your car, any unused fuel will go back to the tank, and if you go with more power down the road the pump is already there.

**Killercanary** · 08-04-2008, 11:41 AM

To add to John said, I'd put the GS340 walbro intank 255lph pump in the car. It is more than you need, but its not so overkill that heating the fuel will be an issue. The gs340 is walbro's high volume, high pressure pump. This will work good with nitrous when the solenoids restrict the fuel return line and the pressure goes up. I made 380rwhp with 24's at 89% duty cycle. Its not that I'd recommend it, but it can be done. 24's with your current mods and a modest shot of juice should suffice as I don't expect that you are making anymore than ~235rwhp now. If upgraded heads are in your future, then a 30lb injector may be the better choice.

**mike** · 08-04-2008, 11:42 AM

Originally Posted by Killercanary

Question for Mike above...

Although I never have, and probably never will run nitrous I have always had the impression that a wet kit on a 5.0 mustang is a roll of the dice due to fuel puddling in the back of the intake and the increased risk of a nitrous backfire in the intake due to it. I've seen a few of these "bombs" over the years on the net and wondered how you avoid this situation? I know that plates and other such devices have become available to inject the nitrous/fuel mix into the lower intake, is that the only safe way to run a wet setup on a 5.0 mustang due to the upper intake plenum design?

A plate system certainly would be "safer" but a single "wet" nozzle, properly tuned (relatively easy), running a reasonable hp hit (ie. up to 150hp) a high volume fuel pump and either a MSD RPM switch or MSD window switch properly configured should eliminate any intake backfires. As with any modification there is the risk of component failure in which case all bets are off.

EDIT: Another assumption here is that you are using a WOT switch. Without it. if you're system is activated and you lift - KABOOM.

**mike** · 08-04-2008, 11:53 AM

Originally Posted by Killercanary

This will work good with nitrous when the solenoids restrict the fuel return line and the pressure goes up. I

Why would your nitrous solenoids restrict your return line?

**349Stroker** · 08-04-2008, 12:00 PM

A GSS340 intank pump will work but in your case you will be pushing the fuel pressure over 90 lbs with 24's and the GSS 340 is flowing 255@ 70 psi.To be on the safe side i'd run the NOS inline pump(15763) along with the intank pump

As for wet kits I have run them on a few cars and like them alot better due to them not having to run high fuel pressure.My kit of choice is Compucar.I have had nothing but great sucess with Compucar and can be bought on ebay brand new for $419.00

24's will work on what you have and a dry kit but you get heads then I'd go to 30's

IMHO get a Compucar kit and put the 150's in

As for timing I'll keep that to myself cause I run alot more than most and a ton more than NOS tells you to do so but I have also went 10's with a hci 306 and a 150 shot

**mike** · 08-04-2008, 12:07 PM

Originally Posted by 349Stroker

I have also went 10's with a hci 306 and a 150 shot

Nothing speaks like experience....

Another assumption: If you are going to run over a 75hp shot consider pulling some timing. I believe the "standard" recommendation is 2 degrees for every 50hp but as 349stroker stated standards are not always optimum

**Killercanary** · 08-04-2008, 12:35 PM

Originally Posted by mike@OSTdyno.co

Why would your nitrous solenoids restrict your return line?

To increase the fuel pressure in the rail, same with an FMU on a forced induction car.

**mike** · 08-04-2008, 12:53 PM

Originally Posted by Killercanary

To increase the fuel pressure in the rail, same with an FMU on a forced induction car.

I'm sorry, I thought you were thinking of putting the fuel solenoid for the n2o system on the return and wondering why....

**John4cam** · 08-04-2008, 01:17 PM

Originally Posted by 349Stroker

A GSS340 intank pump will work but in your case you will be pushing the fuel pressure over 90 lbs with 24's and the GSS 340 is flowing 255@ 70 psi.To be on the safe side i'd run the NOS inline pump(15763) along with the intank pump

As for wet kits I have run them on a few cars and like them alot better due to them not having to run high fuel pressure.My kit of choice is Compucar.I have had nothing but great sucess with Compucar and can be bought on ebay brand new for $419.00

24's will work on what you have and a dry kit but you get heads then I'd go to 30's

IMHO get a Compucar kit and put the 150's in

As for timing I'll keep that to myself cause I run alot more than most and a ton more than NOS tells you to do so but I have also went 10's with a hci 306 and a 150 shot

I thought the dry n.o.s kit supplied an inline pump...