In a message dated 96-09-13 21:13:58 EDT, gbaker@anc.ak.net wrote:
<< Has anyone installed a Nitrious (nitrus?) Oxide kit in their MGB? What
are the down sides of the use besided being hard on the engine and can the
engine be built so that the extra stress is not a concern? I know the
performance improvement is great and I wonder how it compares to
supercharging? >>
Have had experience with a few N2O installations (not my own and not on an
MG). The kits are pretty easy to install and are adaptable to any internal
combustion engine. The effect is similar to supercharging _only_ when you
step down hard on the gas, otherwise you wouldn't even know it's there, has
no effect at all. Low compression pistons are recommended for higher boost
levels, but are not required for a mild boost.
The way it works: Nitrous Oxide is an oxidizer, like air in liquid form when
compressed. You install solenoid operated injectors in the air intake, such
as in the air cleaner housing near the carburetor throat. You need one
injector for the liquid N2O and a second one for fuel. If you get
preignition at full throttle you also need a water injector. There's a
switch that activates all injectors at once when you stomp the throttle all
the way to the floor.
What you're building here is a supplementary liquid fueled rocket booster,
and you supply both the fuel and the oxidizer. As such, the sky's the limit
on power output, just inject the correct proportionate parts of fuel and
oxidizer in any quantities you like. It's common to to buy a kit for 50 HP
boost, or 100 HP, or 200 HP, or whatever you want, just depends on the size
of the injectors. The power only comes on at full throttle. At any other
time the engine runs just as it was before the accessory was installed, no
extra noises, no extra power drag, no extra wear or stresses (except of
course when you stomp on it).
The power comes in the form of a fixed added amount of horsepower regardless
of engine speed. As such it adds a lot of torque at slow speeds and less
torque at higher speeds. As to low speeds, the full throttle switch is to
assure that you don't add the power in the form of very high torque at low
rpm's, which would surely mess up the bearings and/or crankshaft. As to high
speeds, since the added power output is independent of engine speed, you
don't need to run the engine past the original redline, so for the milder
power boosts you don't need any internal engine modifications. For an MG
engine the first 50 HP boost is a piece of cake.
For higher power boost, first think torque like a big block, not rpm's.
Added torque means higher loads on the crankshaft, bearings, rods, pistons,
and head gasket. Depending on your power requirements you may need to stress
relieve and surface harden the crankshaft, use stronger bearings, forged
connecting rods (not lighter weight), forged pistons (not lighter weight),
and also add brass o-rings to the cylinder head around each cylinder to hold
the higher pressures. It is also wise to install stronger head bolts and
main bearing bolts. Of course if you're up for an all out racing engine you
can also build it for higher rpms at the same torque, yielding even more
power output, but requiring lighter rods and pistons, stronger rod bolts,
stronger valve springs, maybe lighter valve gear, roller cam, roller rockers,
etc. The old adage applies, "Speed costs money. How fast do you want to
go?"
Speaking of money, the single greatest drawback to one of these systems is
the cost of the Nitrous Oxide. The last time I checked it was about $30 for
10 pounds in your bottle. If I remember right, that amount was good for an
added 50 HP for about two minutes of full throttle operation. Great for the
drag strip, extraordinarily expensive for street use. Suppose you want an
extra 150 HP for 10 seconds. That comes to about $7.50 for one quick
accelleration run. Still interested?
Barney Gaylord -- 1958 MGA
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