Technical > Spud Miller's Cave
Nitro Question.....
mphmotorsports:
Hey Jon.... do my front wheels look familiar? I bought them from you a coulpe of years ago and they are fantastic!!!!! Thanks for the info. I currently run a 0 pump so my pressure might not be as high as yours on alcohol. What was your best time with that alcohol set up? I think I'll be in the ballpark starting off with my set for pure alcohol. High speed has a 94 pill and will crack open at 65 psi. Does that pressure sound okay? Let me know. ::)
JrFuel Hayden:
Our best ET was 6.99, and best speed was 189 mph with the combo listed. ie; 14 nozzles, 1/2 pump, 76 main, 125 lbs pressure.
Your Hi-Speed opening at 65 may be high [ ie fat] with the 16 nozzles. The 0 pump might be too small , that's why I said call Don at Hilborn, he runs a low pressure set-up. The quickest-fastest non-raised runner iron SBC alky Jr Fueler in the world is the McKray-Enriquez-Algire 406 ci , best ET that I remember is 7.14, with a -1 pump, .125 main jet, open hi-speed jet, opening at 49lbs with 16 nozzles. The hi-speed is open at the hit, keep in mind the hi-speed is a pressure regulator in this application. Blown nitro, a different story.
Jon Hansen, Jr Fuel Dragster Association.com
JrFuel Hayden:
I mis-Spoke, an Oops from a guy that builds Spoke wheels, McKray runs size 18 nozzles in their combo, not 16's
Of course there are other parts of a race cars that make for a good combination; gears, converter, wheel sizes, shift points, launch rpm.
Let the motor work in the rpm range it wants to, that's the trick, listening to your motor, as to what it wants.
I'm real glad you like your wheels.
Jon
Spud Miller:
--- Quote from: mphmotorsports on February 28, 2014, 02:08:42 AM ---Going to run 30% Nitro later in the year..... Once I fine tune my Hilborn Injection Stack set up (Changing from 16as to 14as nozzles and setting up High Speed Bypass), do I need to put more fuel to the motor when I put 30% Nitro mix in ( with 14 as nozzles, I'm planning to start out with a 75 main jet) and what about the timing (currntly running 38 degrees) and what about the high speed???
Thanks for the help!!!!!
--- End quote ---
You don't need to change anything for 30% from a properly tuned methanol setup, but the fuel has a higher specific gravity, so the pressure will be higher. Assuming you're not already over 100 PSI or so at the finish line, that won't be an issue. But, for that reason, I would NOT run a high-speed lean out to start with on nitro. It generally isn't a big gain anyway. Once you've made some laps without the HS, then give it a try. The opening pressure will change from what it was with methanol - it'll be higher.
You can sign up for my free tuneup calculator here:
http://fuelinjectionent.com/register.htm
Once you've been accepted, you can login here to use the naturally aspirated version:
http://fuelinjectionent.com/members/unblown.htm
Here's the supercharged version:
http://fuelinjectionent.com/members/blown.htm
If you have an accurate flow tag, you'll get a pretty accurate pressure at 8000. Pressure is proportional to RPM. Getting a high-speed opening pressure from that at whatever RPM you want is pretty easy.
The calculators let you play around with various pumps, nozzles, percentages, pump drive combinations, weather conditions, etc.
Pump size doesn't change your pressure...give this a read for further explanation:
http://fuelinjectionent.com/bigpumpmyth.htm
Spud
mphmotorsports:
Thanks Spud... I'm already setup as a user on your website.... I agreee that I need to get the alky setup right first before starting to add the juice. Does this setup for alky sound close. 356 cu in small block, 0 pump flowing 3.50 gpm@ 4000 rpm , 14as X 3-1/2" long, 75 main pill, high speed set @ 65psi and a 94 pill. Let me know!!!!!!!
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