bigger injectors with NOS 5176 kit?

[blackfire93]

Do you need to get bigger injectors with the 5176 kit or will the stock injectors work? I saw where MN6WS6 ran a 12.36 without the bigger injectors. I was also wondering if this kit comes with a fuel pressure safety switch? Also, if i do decide to get this system, I might be coming back for some help on the install of the system, the 6AL ignition, and the window switch. Thanx for all the help.

[MN6WS6]

I don't have bigger injectors, but I do have Ford SVO injectors. The GM ones have a tendency to lock up under the increased pressures, but they lock open, so while the motor won't go lean, it will flood out. The Ford injectors can handle the increased pressure without failure. Now, you could always go with just straight aftermarket injectors, but the Ford ones are cheaper, readily available, and in my case, considerably cheaper when you find a used set that somebody yanked when they upgraded.

The 5176 does come with a fuel pressure safety switch. The 6AL is a good choice, but a window switch would also be a wise investment. You will also need a hypertech or some other rev limit raising tune to get the most out of the system. HOWEVER, my 12.36 pass was run on stock tune, but the window switch was very limited as to when it came on and off due to that. I think it was at 3000 turn on and like 5300 turn off back then.

[blackfire93]

You will also need a hypertech or some other rev limit raising tune to get the most out of the system.

Did you always have those injectors in there or did you run the nitrous for a while with the stock injectors? Will my tune from madz28 work? It has a rev limiter at 6,000 RPM. I was also wondering if a tune from madz28 would have too much advanced timing, if any, that would cause any problems. Oh, and of course all those other safety components were good ideas.... I got them from one of your previous posts.

[Injuneer]

You don't change your "tune" for a nitrous install. You want to keep the madz28 tune optimized for non-nitrous performance. Then you "tune" your nitrous kit externally. With a wet kit, you use fuel and nitrous jets to adjust the combined A/F ratio of the NA tune + nitrous. With a dry kit like the NOS 5176, you adjust the nitrous with a jet in the nitrous line, and you adjust your fuel with a jet in a the vacuum line at the fuel pressure regulator. The 5176 kit applies a side stream of nitrous (at reduced pressure) to boost the fuel pressure, and hence increase the fuel flow through you STOCK SIZE injectors.

As is pointed out in the first response, the stock LT1 injectors (Rochester Products ball and seat) do not like the fuel pressures that the 5176 kit uses (as high as 85-90psi). I tried the 5176 kit with the stock plug and stock injectors back in 1995, when even NOS didn't know you needed a different type of injector and a non-stock plug. The combo burned the ground straps right off the plugs.... in my mind it did run lean with the stock RP injectors.

After that I ran with the 24# Ford injectors with NGK TR6 plugs, and had no problems.

You likely need to pull some timing from the madZ28 tune, and again, leave the "tune" alone, so the engine makes max power when running without the nitrous, then pull a few degrees of timing externally with an MSD box/retard.

You also do NOT want to rely on your PCM rev limiter. That limiter cuts fuel. You want to cut spark, and again you can use an MSD box for that too.

[fastTa]

When injectors go static, they will create a lean condition. They WILL NOT "flood out" the motor! Ford SVO injectors are rated at a lower fuel presssure than the LT1's. The SVO's are rated at 39.15 PSI. So this means that the 24lb/hr SVO's are technically a "larger" rated injector at 43.5 PSI and up. We're talking roughly 26 lb/hr at 43.5 PSI and higher.

So the SVO 24's would be OK for a 150 shot or less, but I would not plan on jetting any bigger than a 150 with the 24's. If you plan on doing any more significant modification to the motor in the near future, just go with the SV0 30 pounders and leave yourself some room for calibration.

[MN6WS6]

Sorry FastTA, I was under the impression that they locked in the "open" position, meaning that the injector never pulsed and just flowed straight fuel into the engine all the time. That's what I meant with my statement.

I have had the SVO's in my car since I had my nitrous system. I didn't trust the stock injectors because both NOS and Injuneer informed me of the problems with them at the high pressures.

My theory is that you can never have too much safety stuff when it comes to nitrous. My system has several fail-safes built into it to prevent problems. The only thing I don't have on the car is a nitrous pressure switch, but I have gauges on both the bottle and mounted in the center console, so I always know what pressure the nitrous bottle is at. And since nitrous pressure directly affects what fuel jet you should run (although there is a lot of "give" with it), knowing your nitrous pressure is almost as important as knowing your fuel pressure.

[fastTa]

Sorry FastTA, I was under the impression that they locked in the "open" position, meaning that the injector never pulsed and just flowed straight fuel into the engine all the time. That's what I meant with my statement.

I have had the SVO's in my car since I had my nitrous system. I didn't trust the stock injectors because both NOS and Injuneer informed me of the problems with them at the high pressures.

My theory is that you can never have too much safety stuff when it comes to nitrous. My system has several fail-safes built into it to prevent problems. The only thing I don't have on the car is a nitrous pressure switch, but I have gauges on both the bottle and mounted in the center console, so I always know what pressure the nitrous bottle is at. And since nitrous pressure directly affects what fuel jet you should run (although there is a lot of "give" with it), knowing your nitrous pressure is almost as important as knowing your fuel pressure.

No sweat.

I don't personally use nitrous, but if I did, I would definitely incorporate all the safety stuff as well. I would also use an automatic bottle blanket to maintain proper bottle pressure.

[blackfire93]

One last question before I make my decision. I went to my local performance shop today and they told me that it would cost $4.50/lb. to refill my bottle. Does that sound about right? How long would a 10 lb. bottle last me with the 5176 kit?

[Injuneer]

It can run anywhere from $3-5 for a # of nitrous. With the 125-shot on the 5176 kit, you should be able to get 8 to 10 passes.

One other thing to think about... what are the laws in your state regarding possession of nitrous oxide? In NJ, you can not legally buy or possess nitrous oxide without a permit issued by the State, because it is considered a "controlled dangerous substance" under the drug laws. Fortunately, one of the legal uses, if you check the correct box on the apllication form is "Race Vehicle". Many shops will not fill your bottle in NJ if you don't show them the permit, and some tracks require that you show the permit in "tech".

[blackfire93]

If there is a difference, what is it between SVO injectors and Ford Motorsport injectors? I guess my question is if these will work: http://cgi.ebay.com/ebaymotors/Ford-...spagenameZWDVW

[Injuneer]

If there is a difference, what is it between SVO injectors and Ford Motorsport injectors? I guess my question is if these will work: http://cgi.ebay.com/ebaymotors/Ford-...spagenameZWDVW

I think they are all the same.... Ford, SVO, FMS, etc. I bought mine in maybe 1997 from Internet Racers Supply (since disappered) and they looked just like the ones in the eBay ad you linked..... blue plastic tops. They were marked "Ford/Denso", which I bleieve indicates they were made by Denso in Japan, for Ford. Denso is the Japanese licensee of Bosch, who designed the pnitle style injectors.

The blue tops are the key. The only thing I could think of that would be different would be if they were "matched" for flow. That might differentiate a standard Ford injector from an SVO or FMS one. The ones I bought from IRS were supposedly "flow matched", but who knows.

I've seen dealers use the term "Ford Motorsports SVO Parts".... so it sounds like FMS and SVO may be interchangeable.

[blackfire93]

Does anybody know if the stock 24# injectors will work off of a 2004 mach 1. I have a friend who would probably give me a pretty good deal on them.

[capncrunch]

You don't change your "tune" for a nitrous install. You want to keep the madz28 tune...

As is pointed out in the first response, the stock LT1 injectors (Rochester Products ball and seat) do not like the fuel pressures that the 5176 kit uses (as high as 85-90psi). I tried the 5176 kit with the stock plug and stock injectors back in 1995, when even NOS didn't know you needed a different type of injector and a non-stock plug. The combo burned the ground straps right off the plugs.... in my mind it did run lean with the stock RP injectors.

After that I ran with the 24# Ford injectors with NGK TR6 plugs, and had no problems.

You likely need to pull some timing from the madZ28 tune, and again, leave the "tune" alone, so the engine makes max power when running without the nitrous, then pull a few degrees of timing externally with an MSD box/retard.

You also do NOT want to rely on your PCM rev limiter. That limiter cuts fuel. You want to cut spark, and again you can use an MSD box for that too.

Injuneer-
I am running a Power-dyne SC with 4.5 lbs boost, but I am going to the 6 lb pulley. Is there a formula to calculate what injectors I need to run? I have a Walbro 255 lt/hr in-line fuel-pump, & am running Bosch +4 plugs, MSD wires, & a MSD 6A box.
Any advice on this setup would be appreciated!
Thanks!
John

[Injuneer]

How do you add the extra fuel for the boost right now - FMU, tune, etc?

[capncrunch]

It's got the FMU, but the only tuning was done with an HPP3. I was thinking about eliminating the FMU & going with bigger injectors. Then, I was going to have it dyno-tuned.

Sorry Blackfire, don't mean to hi-jack your thread!