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Discussion Starter #1
When I Bought my Nitrous plate kit, the ad in Summit said,"Fully adjustable from 50 to 150 HP."

I just got out the instructions and they read the average power gain for a 350 cubic inch engine (I have a 351C) with the smallest jets is approx 100 HP.

Now this is TWICE the HP the ad says, and twice the HP I was planning on running. Am I ok with the 100HP level??
The jet sizes are 47/53 Nitrous/fuel I believe and they are the smallest in the kit.

Any thoughts?

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Don't worry about it Mike, no biggie....100 hp from a nitrous system is minimal...

I wouldn't even bother with one for less than that...the work involved and cost don't justify it, IMO...

Your engine will be fine unless it's running on the ragged edge right now...

Just remember.....fuel pressure, fuel pressure! *G* And volume too....

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Discussion Starter #3
I have a Red Holley Electric pump, and I have run 3/8 steel line all the way up to the engine compartment. I have a Summit regulator as well. Is this ok?

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Yes, you should be ok...remember to run a good fuel filter in the line going to the nitrous system...don't want any chunkies in the solenoid or nozzles...

For a small system like yours, 3/8" line is OK but, if you plan on stepping up in the future, 1/2" would be preferable....then all you'd have to do is change to the blue pump...

I realize the outlet in the fuel tank is smaller...at some point that can be a problem too...but the frictional losses in the long line to the front are what necessitate the larger diameter line...

Pat
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Discussion Starter #5
Pat,
I was planning on this line supplying both the 670 carb and the fuel for the nitrous. The bottom end of the enging is stock, so I do not believe it can take more than the 150 shot. With this in mind, am I ok to run both the carb and Nitrous off of the red pump? OR should I utilize the factory line and Mechanical pump for the carb? It sure seems like a wast just to have the electric pump for the Nitrous......

I realize that if I ever rebuild the motor and go with more HP and Nitrous that I will need to redo the fuel delievery....but am i safe up to the 150 shot?

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Yes, I think you'll be fine at your present power level with your prospective fuel line and pump arrangement....you might consider employing a low pressure switch in your fuel line that would shut down the nitrous solenoid if a low fuel pressure situation were encountered...
That might stave off a meltdown from an excessively lean condition that would happen before the engine ran out of gas...
Without interlocks, I wouldn't consider running the engine and nitrous off different fuel pumps....that's too big a can of worms...

Just make sure the whole mess is keyed to the ignition....you want to be the ultimate authority on what's goin' on in there, yes?? *G*

I haven't messed with nitrous in over 15 years so there are likely more knowledgeable folks up to date on the current technology level....

I always tend to err on the side of safety....now that's not any fun, is it??? *G*



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Don't forget to jet up your carb. It takes at least 2 notches up on the secondaries and 1 to 2 notches up on the primaries for even the small NOS jets. Unfortunately, this will make the motor run a bit rich and therefore also a bit slower without the NOS on.

When you first go out to try it just hit it off in high gear first for 4 or 5 seconds and then stop and check your plug color. If you burned the tips of your plugs off you know its too lean, LOL.

After you shut off your NOS stay in the motor for a full second. Its still all up in the intake and if you shut it down abruptly and immediately get off the gas you can get a big BOOOOMMMMMMMM.

If you don't have a low fuel pressure shut off it would be wise to at least put a fuel pressure gauge in there where you can see what its doing.

I would just go ahead and put in the second fuel pump for the NOS.


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Discussion Starter #8
Very good and sound advice from everyone. I have an MSD timing control to take care of the retard for the nitrous. I also have a Fuel Pressure gauge, a WOT switch, a covered arming switch, and a momentary switch on the shifter.(Go Baby Go..hehe)

I do have a question, however. This is theory, and I am sure there is a real world reason as to why you must increase the jets, so here goes.

Why must I up the jets? I thought that the "extra" fuel that is needed for the added combustion rate came from the fuel solenoid. In my mind's eye (I love saying that) I shouldn't need to up the jets because I SHOULD be getting the extra fuel from the Solenoid.

Having said that, I realize I am talking theory. My assumption would be in the real world the fuel solenoid isn't optimized or set correctly?? Am I close?
Please explain the "reason" for upping the jets.

Thanks. I just love the knowledge on this board.



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I don't know the official, technical, engineering answer.

I helped a buddy one night with his Fox stang, 351W, Demon 750 that he had just put a plate on. After the first run we could barely get the spark plugs out of his aluminum heads. He said he thought it had run a bit lean even though it picked up around 6 tenths. When we finally got the plugs out the wire pins had burned off all the way down to the threads. I said, looks a little lean to me too, LOLLLLL. I asked him, you DID jet up your carb didn't you? He says, huh? .

My understanding is that even though the NOS and fuel are being mixed in your spray bar, the NOS has so much oxygen content in it that it is inherently a leaner mixture. That requires you to rich up the carb side of the system, especially in the secondaries when the juice is flowing. Another reason I can think of is that the NOS bar is designed to work with your carb and the carb has a lot more adjustability in it. The NOS side has a couple nozzles and thats it. Maybe the NOS is purposefully calibrated a bit lean to allow you to fine tune it on the carb side.

The more you spray, the more it flows, the more horsepower you make and the more you have to jet up the carb.



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Discussion Starter #10
Thanks for the input. I bought one of those fuel mixture gauges, and I am installing an O2 sensor in one of the Headers...so I SHOULD be able to monitor my rich/lean mixture and make adjustments. I have never been any good with carbs, and it is just because I haven't spent enough time with them. I figure this should help in setting up the carb.

Thanks again for the input.



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