mattg

so what happens if you are spraying and hit the rev limiter?

i know that running lean is no bueno when using nitrous, and the fuel cutoff would certainly lean it out a bit, correct?

is this the beauty of the cpu controlled systems like zex?

would it automatically shut off the n2o

TheModMole

if you use an "intelligent" controller that only activates at WOT(Wide Open Throttle) and you hit the limiter WOT is killed and nitrous stops spraying

mattg

what if you don't have the "intelligent" controller ?

DigiBox

From what I understand, when you hit the rev limiter, gas only goes to certain cylinders. If that is true, then when you are spraying, only nitrous is being burned. That's not good.

I'm sure someone else can explain.

Pick up an RPM switch that will cut any N2O system off before redline.

I almost hit my rev limiter in Oregon at the meet while spraying. Scared the ish out of me.. Thought I was going to have a long walk home.. LOL.. Luckily for me, engines aren't too expensive.

haiduc

you backfire through the intake and make nerf-balls out of the air-filter.

i wouldnt worry about it if i was you, automatics make sure that you dont bounce off the rev-limiter.

but yeah.. TheModMole is also right. if you have ZEX it's only activated by WOT. other systems are not, such as NOS or NX.

fastvtecCL

hey mattg,

look at my sig, the RPM activated switch.. it about 40 dollars and what it does it cut of the nitrous before you hit the rev limiter so incase you do hit it your fine...

bnavarro

Where do u get that switch?

scalbert

Nitrous does not burn on its own; it is used to supply additional oxygen to aid in combustion. But fuel is still required. If there is no fuel in the cylinder and charge air with a nitrous mix is introduced; nothing will occur.

The worry would be if small amounts of fuel remain in the cylinder or somehow gets introduced then you could have a lean problem.

What also needs to be known is if fuel and spark are cut when you hit the limiter. If so there is no worry except for the wasted nitrous going down the exhaust.

allmotor_2000

If you are running a 'wet' system... I'd be a tad more careful because you are sending fuel as well. A lot of WOT switches use the throttle-body (like the NOS switch) to manually activate a little micro-switch... this won't do anything when you hit limiter.

I am not sure how 'intelligent' kits work... if they take the signal from the TPS that doesn't help either! I don't think these kits are
that intelligent to monitor the ECU firing signal!! I might be wrong here. Products such as the Jacobsen Mastermind come into memory.. but this was from yesteryear!

A few safe bets are an RPM activated on-off switch... turn on the N2O during WOT AND 3K through 7.1K RPMS only. Some people have used those Autometer guages with the dual-stage shift-light for this... but a more elegant approach is to get an RPM activated switch from MSD or something.

High compression, N2O and fuel don't mix too well sometimes... even without a spark.