sleeperfc

hey guys.

my setup has been gone over plenty of times. ill list out my full current list of mods if it comes to it. This thread is aimed to answer a few questions about spraying on top of boost.

I have read "Nitrous Oxide Injection on a Rotary Engine
By Sean Cathcart"

http://1300cc.com/howto/how2/NOS.htm

i have actually read this a few times. It seems that this write up covers spraying on a stock turbo setup and never really touches spraying on a full t4 with stand alone setup.

I would really like to know if anyone has some input on the safe limits, jet sizing, timing retard if need be, and any other tuning aspects of running nitrous.

also any input on how using a small shot for spool would be used... stop spraying at full boost?
Why not just spray it the entire rpm band?... (3k-7k)


any tech info relating to nitrous on a turbo rotary belongs here.... flaming post do not. thanks.

No_Rotor_RX7

last i checked, baby seals were posted in the 1st gen section.

pp13bnos

iTrader: (1)

I was also thinking about this recently. My goal was to help keep the intake tempatues down though.

My question was what size of a shot would be needed for cooling the intake charge, while trying to keeping the nitrous to a minimum?

CJ

No_Rotor_RX7

if you are seriously only trying to reduce temps.... albiet this is a crazy way to do that.... i would go with something like a baby seal shot. more like, a 15shot. if that's even possible aahhaha.

actually, just spray the intercooler

ajhehr

I think the question is

if you have a full t4 + standalone, why would you want to spray?

if you want more power, use a methanol injection and turn the boost up.

if you want a cooler intake charge or egt, use a methanol injection and turn the boost up.

If you dont want to use a meth injection, then use a CO2 system with a intake cooler and a intercooler sprayer.

The meth injection units are going to be cheaper than a no2 setup, and cheaper in the long run (methanol is at $2.75 a gal last I checked) and I charge $25 dollars for a 10lbs bottle fill (about 10~15 passes)

Now if your running a BIG turbo and you want to spray for spoolup and EGT, go ahead. but the T4's spool so nice on the 13b's I dont think you need it.


But if you still want to spray, I must say it is a magical experience, One you will never forget!

MichaelB145

Eventually I would like to do the same but I would like to get the car to it's full potential without nitrous first.

pp13bnos

iTrader: (1)

I've sprayed upto a 200 shot on a injected peripheral port 13B. Never with boost though.

When I've ran nitrous on my old cars, the intake manifold would often turn frosty after a hard run. I doubt it would cool the intake charge down that much on a boosted rotary, but I question if the methonal would cool it down even that close. CJ

scathcart

That write up sucks. Ignore it for anything other an introduction to nitrous. I've been meaning to redo it, but I've been meaning to do a lot of things lately. Never enough time, blah blah blah.

I bet I'd be more productive if I was castrated.... anyhoo...

The poster above raises a good point... why use the juice when you've got a T4? Boost response should be a non-issue, and if you want more power, you'll need the high octane with nitrous anyway, so just crank up the boost.

A couple quick notes on nitrous with turbos:

I never bother with it on stock turbos. The wastegates are too small to handle the exhaust products of nitrous, and the turbo will creep; no matter how much you port it. You might be able to get away with a 50 shot, but when you're spending that kind of coin on a nitrous system, its always cheaper to simply put that money towards a better turbo/intercooler or scrap the turbo all together and
go with a BIG nitrous shot.

Nitrous' cooling effect is big... its a very effective detonation suppressant. It comes out of the nozzle at -127 fahreheit; very chilly. It is not uncommon for intake manifolds and nozzles to form frost on them, even on turbo engines. Be careful, those temps can burn you.
Intake charge temp is the biggest cause of detonation... but, as well put-above: methanol injection/better intercooler can do a fantastic job of taking care of charge temp all on their own.

So... with a boosted engine, why?

I suppose I can think of a few reasons, but let's hear yours.

hondahater

iTrader: (2)

faster 1/4 mile times
more torque down the 1/4
get the car off the line faster
spool the turbo before you are actually going(guess you could brake boost or use your two step but you get what I'm saying)
lots more reasons but these are some. Would love what you have to say scathcart

rarson

I personally think that people using nitrous to "spool" aren't using it the way it should be. Nitrous adds power on top of the turbo, throughout the band, and it really shouldn't be sprayed at low enough rpms to actually help spool, unless you've got some huge monster turbo.

Now that is the absolute biggest waste of nitrous ever. I really don't see why people continue to waste it like that! CO2 will provide just as much cooling, without utterly throwing away potential power the way spraying N2O would.

For cooling effect, I'd have to recommend either meth, water, or a mix injection system. Pre-compressor will likely give you the biggest cooling benefit. In fact, spraying pre-compressor water will give you what is commonly referred to as "quasi-isothermal" compression. As air is compressed in the volute of the compressor, it gains heat, and thus is called "adiabatic compression." "Isothermal compression" is the theoretical maximum efficiency of compression without temperature increase. "Quasi-isothermal compression" is a real-world, attainable compression that occurs with pre-compressor injection that results in very little temperature increase, resulting in a huge increase of compressor efficiency.

It's not widely attempted, mostly due to the stigma of damaging compressor wheels, but real world results of others (I haven't built such a system for my own car yet) has shown that compressor wear is very little, if at all, affected by the water injection. You're likely to get more wear by running with no filter than running with pre-compressor injection.

Do some more research on pre-compressor injection here.

Turblown

iTrader: (12)

What about thermal shock to the compressor overtime Rarson? I have been running water, water meth, meth precompressor for a while, and I've been told by crediable sources that overtime there is problem with thermalshock to the compressor.

sleeperfc

well MY reasons are...

i have a stock port s4 motor and spoolin my t70... well it takes all or nothing. i get full boost by 5k. Get a smaller turbo some might say... well...
The turbo is just right on the highway, I do mostly highway pulls where i live. I can brake boost just fine. So i plan to keep this t70.

One problem I hope to solve with spray is lag. Id love to have a wider powerband when need be. Killing lag at the drag strip mainly... but having it on tap would be nice for "spirited driving."

Another reason Im thinking of spraying is: Adding another 50-75whp. I have about 40k miles on my stock port, 8.5:1 motor. For me to make 400 on this setup is gonna mean race gas. I would like to keep the boost low and 93 octane friendly... but i still want to make 400+whp.

I thought of just running a water/meth or straight meth injection setup and running the 19/20psi it is going to take to make 400whp on this motor. The main problem i have with that is that I would still have this lag issue and I would have a permanent tune to the injection. Tuning to this meth injection is gonna be a headache id rather not deal with seeing as ill still be laggy as hell.

soo with a 50 shot i could fight lag, add 50whp+ and get my 400 mark on pump. Im confident that i can do this safely with a tuned, wet nitrous 50 shot.


input?

hondahater

iTrader: (2)

you just need to port your motor and be done with it as well as get alky injection. When your done and still not satisfied then come back

1wide7

iTrader: (1)

i was thinking of doing a 40 shot for spool as well
i was going to run a full throttle switch to activate the system then use a window switch set to 10 psi to turn the nitrous off
a lot of people turn it off because boost becomes very hard to control with the nitrous on some of the drag racers were running nitrous aswell maybe we can get them to chime in

LUPE

Spray the world at it.........

SilvioRX7

sleeperfc

ahh jeez why didnt i think of that...

yes at some point i plan to get a port... but my 40k mile motor is not comming out any time soon for a port. I dont have money for a port right now.

I do on the other hand have the money to buy a nitrous setup to get me by till i can afford a full out port/build.

sleeperfc

yea... too bad that's not a turbo or a rotary. other then that its totally relevant!

scathcart

Get the car off the line faster? That assumes nitrous is being used at launch, which means a couple things:

- Using a WOT switch, the pedal will be to the floor, car sees next to no load as you slip the clutch. This means rev limiter/two step. Bouncing off the limiter with the nitrous engaged is just asking to be picking up the pieces of your intake manifold/ fuel system off the starting line. Yuck. No fun.

- You use a WOT switch, but you don't floor the car until you see the green. You've got an extra 100+ ft lbs of torque, and no extra traction. Tires spin, and you hit the window switch/limiter. Not much faster than before. Maybe slower.

- Same as before, but as the tree flashes green, you dump the clutch, car actually gets traction, and the engine bogs. Those tires stick and you're instantly trying to move 3000 lbs. Laws of physics aren't on your side. Should've launched higher. Or used a BB V8. nonetheless, large bang and you watch you throttle body leave through the hood. Who needs a TB anyway?

- You're deep staging your PP turbo, mated to a 'glide with a 5K stall and the transbrake engaged. Let's be honest, if you've built this car, you're not asking any questions.

Can you use nitrous at launch safely? Sure. But who launches perfectly all the time? Too much risk in my opinion, and launches are almost always traction limited anyway.

Unless you're using an absolutely fantastic controller, using nitrous on launch is a very fast method to nitrous backfire. Bog the engine or hit the rev limiter, and you're just blown something apart. The nitrous system isn't tied into the rev limiter (agian, unless you're using a fantastic controller.) A window switch can save you from the rev limiter, but when the window switch kicks in, you're not using it at launch, and that's an instant loss of a large amount of torque. We don't want that. We want more torque. That's why we got a turbo.



So we want a nitrous system for power below 5000, and more peak power without more boost, or, actually, without more octane. Maybe not... maybe we want more power with our current turbo without going vastly outside the compressor's efficiency. Nah. We just want to use the pump premium, and go fast. Screw the VP, too much hastle.

Fine. Let's do it. 50 hp on 93 for a 400 hp goal is absolutely fine. Retard the timing a little more, keep the split in check, keep the AFR's at 11:0 at peak torque, and monitor detonation. The spray should drop the charge temps a little more, battle off detonation (EVIL!).
Seriously, nothing wrong with it. Use a purge valve and a pressure monitoring bottle heater, a 3000 on- 7500 off window switch, and hit it in first gear. Watch those tires spin since you've just dropped an extra 87.5 ft-lbs on the drivetrain. Or get traction, and go pick up your half shafts. You wanted 4130 ones anyway.

What else is there to know?

Well... boost spike. Better hope your wastegate and piping is fantastic. Those extra nitrogen and oxygen molecules will really try to overspin that turbine. (Yes, I know, thats the point, you want less lag/better boost response, but not to the point of overboost). If you're wastegate is up to the task, there's no problems. Like so many others, been there, done that. Dunno why there's such fear about it.

Jay7 Nyc

iTrader: (3)

Noone else has tried a nice evenly distributed 50-100shot to help spool up those big turbos?

BLitzed33

there are ones who have/and use nitrous...ray wilson, steve kan, dee, ari yallon.

NissanConvert

iTrader: (1)

I've heard quite the contrary on many boards. The compressor doesn't care whether the particle is a water droplet or a grain of sand at the speed its moving pitting will likely happen with sustained use. I've also read reports by credible sources (AI vendors) not to spray pre-aftercooler (intercooler) or temperature drop across the core could lead to condensation which is precisely what you don't want with your ai system.

Using nitrous to enhance boost response i'd start the spray around 3000 with a first gear lock-out. Some of the programmable systems would allow you to wean off the nitrous progressively as boost goes up maintaining a reasonable power band. I must admit though that i've never used a programmable system. And I for one would spray from 3k-7k on top of boost.

At the track when are you below 3k anyway?