Good information Mike. Thanks
-----------------------------------------------------------------
Steven St.Laurent
Test Engineer
Test Branch, GSD,MCTSSA
MARCORSYSCOM, US Marine Corps
mailto:stlaurents@mctssa.usmc.mil (work)
mailto:Saint1958@home.com (home)
Office: (760) 725-2296
-----Original Message-----
From: Mike Schwall [mailto:mschwall@flash.net]
Sent: Wednesday, March 01, 2000 7:32 PM
To: dakota-truck@buffnet.net
Subject: DML: Nitrous info
An old timer on another list I'm on posted some good info on nitrous
setup. It's for carbed engines, but the info is still useful on
EFI. Permission granted from original poster for cross post.
----------
Mike Burch - N2OMike66@aol.com
Been seeing a lot of questions about nitrous lately... I made this
post to fordnatics last year or so, but it looks like the material might
be due for re-posting....
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...
Mostly geared to a carb system, but applies to all.... Here Goes!!!
----------------------------------------------------------------------------
-- ------------- 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 reccommend 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 porcelin. 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 seperation 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.mustangworks.com (user rides, nitrousmike66) http://www.fortunecity.com/silverstone/healey/367 -------------
Mike
__________________________ mschwall@flash.net
This archive was generated by hypermail 2b29 : Fri Jun 20 2003 - 11:49:30 EDT