Here ya go...

Before you start, make sure to have a bottle heater and pressure
gauge, along with a fuel pressure gauge and regulator for the nitrous
enrichment. A good ignition system is also mandatory... one that
doesn't keep advancing the timing to the moon as the engine revs.
It should STOP at around 36 degrees total. (with the nitrous off)
Check it!!!!!! Wild advance KILLS nitroused engines...
Factory distributors are really bad about this.

Mostly geared to a carb system, but applies to all.... Here Goes!!!

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Now that we've got the juice, how do we have fun with it?

Well first off, you don't want to get anxious and hurt your
engine... Once the system is properly installed, check to
be sure its fuel enrichment is working properly. Turn the
nitrous bottle off, arm the system, and with the revs around
3000 rpm, tap the button. The engine should fall on it's
face. It should be about like hitting a kill button.

Now that we know it works (the engine is getting enrichment fuel).
Let's see what other items are necessary...

-COLDER spark plugs! Do NOT use Split Fires! For the street,
use the coldest non racing plug you can find... especially
if you might have to use the system with pump gas.

-A bottle heater and pressure gauge! You MUST know what your
bottle pressure is to get consistent results! The gauge tells
you the pressure, the heater allows you to control it. Keep it
around 900 psi for best performance.

-Fuel... Use the BEST you can find! Detonation on nitrous can
lead to some VERY un-pretty things! Straight pump gas should
not be used on systems over 125hp on a 302. These engines with
their 10 7/16" head bolts are prime game for blown head gaskets
if everything isn't right. A little detonation goes a loong way
on these motors...

Make sure you have a good ignition system with good wires.

**** Now that you are set up, how is it tuned???????? ****

First is timing. The timing NEEDS to be retarded about 3
degrees for every 50hp of nitrous boost. If you don't, it's
bye-bye head gaskets, or worse! You need to go with the upper
end of this scale when pump gas is used (even if you add octane
booster). Just DO IT!!!!! I use MSD's Multi-Step Retard to
do this automatically anytime the nitrous is engaged.
If you are in the market for an ignition system, The MSD Digital 6 Plus
costs $279, has a timing retard, a two step rev limiter, plus
is adjusted by little dials. (instead of chips)

******** FUEL SYSTEM ********

To start, make SURE your fuel system is able to maintain
full fuel pressure at full throttle high rpm with the
nitrous engaged! It's better to be safe than sorry here.
I've seen cars break into the 10's with a single Mallory
140 or Holley Blue pump, but wouldn't really recommend it.
I use two Mallory 140's on my car. One for the engine, the
other for the nitrous.

******** FUEL PRESSURE ********

If the fuel pressure is too high, the car will exhale a bunch
of black smoke out the exhaust, and will not run anywhere near
its potential. It will feel very lazy (well, for nitrous).
We want to lean it out, just not toooo far.
My buddy's 2V 351C Mach I went from 9.00 to 8.50 in the 1/8,
just from lowering the fuel pressure!

Start with the smallest hp jets, with the fuel pressure turned
up extra high. This will ensure an extra margin of safety.
With the tranny in neutral (park), bring the revs up to 3000
and tap the button. The revs should jump up a bit. Probably
not super crisp or fast... just kind of a 'VROOOOM'. Do this
with the bottle pressure at its operating range. (850-950 psi)

If it hits EXTRA hard, like BAM! You are probably a bit lean,
and need to increase the fuel pressure.

We can now start to decrease the fuel pressure....
Do this with the car in neutral. Starting with the pressure
high, we are going to be tapping the button at 3000 rpm as we
gradually decrease the fuel pressure.

As the fuel pressure is lowered, the engine will start to respond with
increasing aggressiveness. The VROOOOOM will start to turn into
a BANG! When it BEGINS to get pretty crisp, it's time for a road test!

At full throttle around 3500 rpm, hit the button and hold it
for 3-4 seconds. The car should respond in a positive manner.
As you let off the button, kill the engine, coast to a stop,
and check the plugs. They should look clean, but have NO specks
on the porcelain. If they do, it's aluminum from the pistons,
and the fuel pressure needs to be increased. Chances are, at
this point it will still be a little rich, and you will find no specks.

Decrease the fuel pressure a little at a time while making the
above test. As soon as you begin to see ANY specks on the plugs,
raise the fuel pressure a half pound or so, and you should be
close to optimum for that hp level. If you want to try other
jets, you need to go through this same testing procedure again.
Start rich, and work your way down.

You will be **AMAZED** at how much better a nitrous system works
once the fuel pressure has been optimized!

**** Other things that help optimize a nitrous equipped car ****

- A good exhaust. BIGGER is BETTER! 3" pipe and mandrel
bends rule in nitrous applications!

- Proper camshaft. A lobe separation around 110 deg is a
good compromise on a carbed street engine.
Some extra exhaust duration is also a plus.
8-12 extra degrees is good. To maximize
nitrous performance, go to 112. 114 on an
EFI car.

- Compression. Low compression makes tuning a lot more
forgiving. Make the same mistake with both
a high and low compression engine, and your
chances of living through it are MUCH better
with the lower compression.

If an engine is a little low on compression
anyway, (5.0 with a cam for example) nitrous
can bring in a SERIOUS wake-up call!

Good Luck, and HAVE FUN!!!!

------------------
Mike Burch
66 mustang real street
302 4-speed 289 heads
10.63 @ 129.3
http://www.geocities.com/carbedstangs/cmml_mburch.html
http://www.fortunecity.com/silverstone/healey/367
http://www.mustangworks.com/cgi-bin/moi-display.cgi?220

As previously suggested, you need to check "flowing" fuel pressure.....if the fuel pressure was too high it can also cause it to nose over and sputter....

------------------
69 fairlane 351w [email protected] in search of Body parts for 69 fairlane
66 brand x outlaw s/s
Fstln69 Pics Page
http://community.webshots.com/user/purple66bu

quote:

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Originally posted by MandarinaMustang:
Thanks for the replies....I'm using an Edelbrock system with the 50 shot. Bottle pressure was around 900-950.Initial timing was set at 12* with nitrous (15* on motor), vacuum advance disconnected, only mechanical. I've always ran 5.5 lbs of pressure because that's what the kit suggested.
Like I said it's very likely that the problem is nitrous related, not fuel. I made two runs before the problems started, I haven't been able to diagnose it because of work.
Thanks for the pointers I'll keep you posted.

Alex

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What are you running for ttotal timing??? Are you checking fuel pressure flowing??

I put a fitting between the solenoid and the regulator so I can attach the gauge or cap it when not in use. I like the fitting to be actually screwed into the regulator. I attach the gauge to this and the other end goes back into a gas can. I like to have a shutoff valve in the line that goes to the gas can so I can turn it off and on while flowing several times to see where the pressure stables out. I use a 73 Holley jet to flow the system so what ever equivalent nitrous jet that is (don't have by chart with me). You can also use the size jet that NX recommends with their tuneups. If the car normally runs with an alternator I will hook up the battery charger to bring the voltage up to around 14 volts so the fuel pump will be at the speed of what it is when going down the track. If you don't use an alternator then do not have the battery charger turned on. Two man job for safety have a guy in the drivers seat to turn the fuel pump on and then check the fuel pressure, turn the valve on andf off a couple of times to shock it (like a solenoid turning on) adjust the regulator, now shock it a couple of times and reset if required. DO NOT FORGET TO PUT THE CAP BACK ON THE FITTING like I did. When Joe armed the system it started pumping out fuel all over the place. We were lucky and didn't have a fire. See if you understand all that. Let me know.

First you have to understand that nitrous systems really do not flow that much fuel. Shannon Jenkins uses one pump for both the nitrous and the carbs. To spray 300 hp of nitrous at a BSFC 0f .5 requires 150 pounds of fuel per hour flow. Pump gas weighs 6.15 pounds per gallon so that equates to flowing 24.4 gallons per hour or .4 gallons per minute. I bet your MagnaFuel pump flows more than that. 450 hp tuneup requires .6 gallons per minute. 150 hp only requires .2 gallons per minute.

The MagnaFuel regulators are more stable than the Holleys but everone uses the Holleys so I do also. I have never understood it. The Holley regulators and most other regulators cannot control of 14 psi unles the spring is modified.

If we suspect it's a carburetor or fuel issue try this: When the car is laying over...(if it a dominator) back off the throttle a little and see if it picks up and accelerates a little better for a moment. If it does, it's lean. Typically if its an ignition issue it'll pop or surge sharply. The muted toned is usually due to lack of fuel that makes all the sound. You can also pull the plugs out or look in the header after making a run and/or lifting off the throttle before the engine is mysteriously picking back up. Then read the plugs and see if the plugs were cleaned off by lack of fuel. Check your fuel system for any chance of heat or vapor lock and keep fuel lines away from heat. That will create vapor in the lines and cause some pretty definite surges when it hits the bowl, yet your fuel pressure will remain high but will fluctuate.

quote:

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Originally posted by Fstln69:
They make a flow checker but you could use your plate (off the car)you turn on the pump activate the fuel solenoid and then let the fuel fow into a pail and set your pressure.The flow checker is a deal that you take your fuel line after the solenoid and connect to it with the prescribed jet in it and flow and set your fuel pressure.This is the only way to set fuel pressure for nitrous.You are setting it while it is dead heading into the solenoid and it will drop after the solenoid is activated.I will try to find some more info as i am probably confusing more then helping.
dennis

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Dennis (& everybody)you've been very helpful!Thanks....
It does get a little confussing sometimes, but I'm learning..I've seen that method you described of flowing with the plate, I just figured it wasn't really necessary for such a small amount of N2O....
I'll see when I have a chance to really go over my system...well at least now I know how to CORRECTLY set the fuel pressure.
Thanks again!

quote:

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Originally posted by MandarinaMustang:
Dennis (& everybody)you've been very helpful!Thanks....
It does get a little confussing sometimes, but I'm learning..I've seen that method you described of flowing with the plate, I just figured it wasn't really necessary for such a small amount of N2O....
I'll see when I have a chance to really go over my system...well at least now I know how to CORRECTLY set the fuel pressure.
Thanks again!

Alex

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Alex its important no matter how much nitrous trust me!
Anytime glad to help out
Dennis