I know that to run a good amount of nitrous, forged internals are needed to handle the increased cylinder pressures, but I'm curious as to what compression would be ideal for a nitrous application on our engines. I know that lower compression is beneficial for turbo/supercharged applications because they're harder to keep from detonating due to increased intake charge temp from the pressure of compression, so would this apply for nitrous as well and require lower compression (8.8:1) or would 10.5:1 be tuneable?

sucker MC

When using n2o, there is NO pressure change in the head. N2O basically supercools the intake charge (from my understanding, please correct me if I'm wrong) and isn't "forced" into the intake. Nitrous is a power adder, yes, but it's not like a turbo or S/C wherein those force the air "down your engines throat". I believe a n2o rebuild can be done with higher compression pistons (just so long as they're forged) and forged rods. With higher compressions, tuning becomes VITAL to the survival of the motor.

96 Indy Red Dodge Avenger I4 5spd
225.7whp/227.2wtq @ 10psi, currently running 12-14psi.
HRC Stage III turbo setup
JE 8.8:1 pistons
Eagle rods
block bored .020" over
GReddy FMIC w/ custom piping
1G crushed BOV
SPEC Stage 3 clutch
2.5" DP, 2.5" high flow cat, 3" ERT catback w/ Magnaflow muffler and 3" tip.
much much more...

very true ^^

myspace.com/coastiecobb

it was my understanding that since N2O is "nitrogen and 2 oxygen" atoms it's adding chemical oxygen into your cylinder that is released when exposed to heat. cylinder pressure goes up cuz thats how you make power, putting more force on the piston and consequently more force uniformly on the cylinder. it's not really super cooling anything, thats just the intercooler N2O spray.

My goal is to run a 13.8 juiced and in street trim(little to no weight reduction). I know that i'll have to rebuild before i get there, but I'm trying to get advanced information so i don't fuck up the first rebuild and have to save another thousand bucks for the second.

The reason I'm wondering if a 10.5:1 comp rebuild is feasible is because i dont wanna go and get 8.8:1 pistons and have my car be sluggish all the time when it's not on the bottle. I still have to drive my car day in and day out and thats my main reason for switching my plans from turbo to nitrous, i can't afford the downtime or the turbo kit. the nitrous kit comes out to be significantly less expensive, and if i can run a 13.8 with my car in street trim, i'll be pleased. It's gonna take more than a 75 shot so i'm planning to run more nitrous but i'm not as knowledgable on the subject of nitrous as i am on forced induction tuning. With nitrous i'm not sure if i'll have a problem with the high comp or not, or if i'm gonna have to find a way to retard the timing or what. I was hoping that somone with extensive experience would point me in the right direction but i guess i'll have to keep reading up on it since i'm not really sure if anyone has run over a 75 shot

it's cool though, i like learning stuff sorry for the long post.

sucker MC

Im doing the same thing you are. Yes you are right in your theory of how nitrous works. If you want a better or more scientific answer goto howthingswork.com. I'm going to go with forger 8:8 je's and bottom end. The reason for the 8:8 is because it gives me more room for error. I have seen people get high 13's with stock bottom end btw, so I dont think you'll have a problem.


Nick
97RS

turbo8u> shut your SUCK
ZAO684: NIPPLE warning...maybe>?

yellowrs has a lot of experience and knowledge of going above a 75 shot. I dont see a problem in going with a little higher compression. And eventually you will need to retard your timing as you upgrade above a 100 shot.

myspace.com/coastiecobb

What ever happened to yellowRS? Last I heard he was running a 200 shot on his car. He almost had my convinced to go nitrous.

he's around but doesnt post alot. yellowrs

myspace.com/coastiecobb

if you run 8:8:1 compression an NA, wont your car be pig slow when youre not stepping on the juice?; hence the reason for higher compression on NA's?

It all comes down to your ability to A) tune the car properly and B) the amount of time you want to spend doing "A)." If you get teh 8.8CR then you have a little more slack in your tuning before you risk detonation. If you raise CR above stock, then you are just that mush closer to the flashpoint where your engine makes nasty little "pingy" noises. If you are a capable tuner and know what to watch for and, more importantly, what to do if things start to get out of hand, you should be okay. It's just that with higher CR you need to pay closer attention.

Maybe I put it like this...
You have a can of gasoline in your hand. You start off standing 5 feet away from a massive bonfire (stock), how much more attention are you going to be paying to that can of gas you got if you move 3 feet closer to the fire? 3 feet farther away? You get the idea now.