Nitrous and High Compresion

TrickFlow · Mar 12, 2004

Ive heard mixed things about nitrous and having higher than stock compression..
I have 10:1 forged TFS pistons, and i was planning on running a 125-150 shot of spray on it eventually, but just at the track. A friend of mine said to get the most out of nitrous, i should have lower compression. I agree with this when you consider superchargers and turbo's etc..
Im lookin at it like this though: if im only going to be using Nitrous at the track, its not worth lowering my compression down to 9:1 or 8:1 just for normal daily driving duties, right?
I just dont want to lower my compression, and lose any horsepower id want on the street, and have to save it just for the track.
Can someone shed some light on this for me? Thanks in advance

Rick 91GT · Mar 12, 2004

Nitrous loves compression, your buddy has been mis-informed. Only blowers and turbo need lower compression....

10:1 is nothing with N2O, just need to remember the higher the static compression the better the fuel needs to be as the shots get higher, you have nothing to worry about just ready the plugs, you may find a mix of race gas at the track will have a lot of gains.

My D/R combo is a much higher static compression (race gas only) and I will use over 300+ of N2O

TrickFlow · Mar 12, 2004

Wow.... 300 + ??? i somehow feel insignificant now.. heh thanks for the info!

bluevenom867 · Mar 12, 2004

Careful about the fuel if your runing a dry kit.Make sure you have an adjustable fuel regulator and high volume pump.If the mix is to lean you'll fry a head gasket.Buy a good timing light too.5.0's seem to like 8-12 int. timing.Try 8 degrees and go up from there.If you thing your losing power go back down.Nitrous motors also need to have good exhaust flow,so you might want to run a larger header than you planed.Nitrous power won't go up as RPM's do,it stays constant.Oh,and if you think 300+ HP is good look at your torque on a dyno.A 75 shot on my almost stock 86 made about 100ft-bls more torque are the wheels.Use race with the nitrous or pump gas with a smaller shot,because some boosters have a chemical that will causes it to detonate or something.Last whacth out for tire spin,150 shot w/ 4.10 gear on my 86 w/ a T-5 will smoke 10in. slicks in first and second!
Have fun and whoop ricers!

notchback501993 · Mar 13, 2004

Nitrous Help

Your 10:1 compression with nitrous should be fine. Remember, the difference between nitrous and a blower or turbo is that nitrous raises the ratio of oxygen in the mixture, not the initial cylinder pressure. In a gas engine your air to fuel ratio must remain stoiometric. If you have a higher quantity of O2 in your mixture it will burn hotter and faster, i.e. hot enough to melt pistons and head gaskets. Nitrous is 33% oxygen, regular ambient air is only around 20% oxygen. Oxygen is the only thing in air that combines with the fuel to combust. By adding more oxygen you can burn more fuel. If you have a higher ratio of O2 to fuel it will burn hot enough to melt pistons and head gaskets. Basically put, it doesn't matter what your compression ratio is, as long as you have enough fuel to supply the proper air to fuel ratio. If you have an engine making 200 horsepower and u put on a "100" horsepower kit, what this generally means is that you are adding 50% more O2 to the mixture than normal, so you must add 50% more fuel to make the proper stoiometric mixture. The only other factor you may want to consider is if you are adding 50% more O2, you are generally adding 50% more power, will the rods, crank and block handle this kind of power??? Nitrous can break a motor 2 ways, the wrong A/F ratio and too much power for the internals or block to handle.

notchback501993 · Mar 13, 2004

notchback501993 said:
Your 10:1 compression with nitrous should be fine. Remember, the difference between nitrous and a blower or turbo is that nitrous raises the ratio of oxygen in the mixture, not the initial cylinder pressure. In a gas engine your air to fuel ratio must remain stoiometric. If you have a higher quantity of O2 in your mixture it will burn hotter and faster, i.e. hot enough to melt pistons and head gaskets. Nitrous is 33% oxygen, regular ambient air is only around 20% oxygen. Oxygen is the only thing in air that combines with the fuel to combust. By adding more oxygen you can burn more fuel. If you have a higher ratio of O2 to fuel it will burn hot enough to melt pistons and head gaskets. Basically put, it doesn't matter what your compression ratio is, as long as you have enough fuel to supply the proper air to fuel ratio. If you have an engine making 200 horsepower and u put on a "100" horsepower kit, what this generally means is that you are adding 50% more O2 to the mixture than normal, so you must add 50% more fuel to make the proper stoiometric mixture. The only other factor you may want to consider is if you are adding 50% more O2, you are generally adding 50% more power, will the rods, crank and block handle this kind of power??? Nitrous can break a motor 2 ways, the wrong A/F ratio and too much power for the internals or block to handle. One morew thing, nitroud generally burns faster, this is why you must retard your timing. If you have too much timing, the pressure will put too much force on the piston ehich is still traveling up in it's bore. This can put too much stress on the rods or crank and crack them.

n2o abusn coupe · Mar 13, 2004

i left my timing at 14 degrees, and sprayed a dry 125 shot on it...

i got backfire and it blew my oil filler cap off, blew a couple vacuum lines off, and made my air filter look swollen.

bluevenom867 · May 19, 2004

Sounds like it when too lean.The timing was high but not high enough too detonate.
Did you up the pressure and have enough fuel?
Also your lucky that you only had that damage done.Most detonation on 200hp shots blows your manifold clear off the motor.Maybe 125 isin't enough to destroy the intake.

QDRHRSE · May 20, 2004

One of my friends sprays 300hp on a 15:1 347. Low nines. As long as the timing is right, the fuel is sufficient quality, and there's enough extra fuel- its no problem. in fact, I swear on my mothers life that there's a guy, here on Stangnet, that has a lot of nitrous and a lot of boost on a high compression engine. Do a search....I think his name is "BradleyStang" or something like that.

Nitrous and High Compresion

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