racers, Sorry I was clicking a bit to fast I meant to qoute this

 

Procco evo made 765 awhp on a gt35r and an 85 shot....

 

And it moves hard as hell.

 

The ignition is retarded because the burn rate is increased with nitrous, not because it's more prone to preignition. The end result is still peak cylinder pressure at the same crank angle. With a 75 shot however, I still ran full timing. I backed it off 3 degrees, got on the dyno, and added it back in 1 degree at a time. It picked up about 12 HP for every degree right up until I was back at my usual timing level. I no longer pull any timing for nitrous.

Nitrous also has the effect of evening out the burn rate across the entire chamber, changes in fuel density become less noticeable. This can reduce knock propensity, in addition to the cooling effect. Just because nitrous is a fuel does not mean that the huge drops in intake temps are not valid. You'd be surprised how much cooling comes from the gasoline itself, and that is the main fuel. That doesn't get much consideration though because it is always there, and we can't measure the temp drop due to the injector's location.

But now I'm rambling... The bottom line is that I knock less on race gas and a 75 shot than I do on race gas alone, same timing, boost, airflow, and AFR.

 

Somehow this sounds counterintuitive to what I have been reading. All N2o Manufactures recomend backing off the timing in an effort to avoid knock. Some of our cars are more knock sesitive than others. Also your scenario was with race fuel. On pump I doubt that you could run that kind of timing. Gad to see that you did this testing the right way. On a dyno! I have been trying to street tune the N20 with the UTEC, but a Dyno is a much better alertnative.

 

The NOS brand is actually garbage as reported by ProccoEvo. Go with Nitrous Express or something.

 

In my case the difference in burn rate was either insignificant, or other factors canceled out the need to reduce timing. I think it's worth mentioning that a 75 shot, in the grand scheme of things, is pretty small. Guys running large amounts of nitrous are going to see much more of this effect than we are I'm sure. Any generalizations like the commonly quoted "retard 2 degrees per 50 hp 'shot'" tend to take an average over a larger scale. At the extreme low or high end of the range they tend to be innaccurate, and I wouldn't be surprised if that turned out to be the case for anything under a 100 shot perhaps.

It's still safer to run less timing, but I would not do it just because that's what the manufacturer's (or even the INTARNET!!1!) say. Adding 50 whp with nitrous and then losing 25 whp to timing reduced unneccessarily seems counterintuitive to me. Natturally YMMV, and slow incremental changes with testing/logging/dynoing is the way to go for maximum safety and power production. Same rules that apply to raising the boost, or any other method of increasing power.

I personaly like the nitrous. My current strategy is to go with a powerful but quick spooling turbo for a fun street car and then use the nitrous at the track on race gas for the bigger turbo timeslips. I did the big laggy turbo thing on the 2g, and wanted to try something different on this car. I'm liking it so far.

 

yup u can

been using it for some time now.and i love it...
if your built then you can hit up to a 125hp+ shot.....considering you have a good tune

 

which one should i go for ZEX,Venom or NOS????

 

I will not go Nos whit Evo, the sadden “shock” to the engine is not healthy to the engine in my opinion.

 

Sudden shock? This isnt the fast and the furious, you dont empty an entire bottle in three seconds. Have you ever run nitrous in your life, if you dont want sudden shock just dont purge, you will have a shot that starts at like a 10 shot and works up as more liquid nitrous gets into the lines. There is absoloutly nothing wrong with nitrous unless your running incredibly aggressive timing curves or an AFR that is too close to leaning out, and let it lean out while spraying. My buddy has been spraying a 150 shot on a maxima for 6 months without a single noise from the motor. Spray is only not safe, when run with an incorrect tune. For example, I know someone who had Al give him a tune, and neglected to say he also ran nitrous, Al made the timing curve really aggressive, and the second he touched the bottle, boom. If your so worried about a sudden increase of HP there are a million and a half ways to get around it. I for example run a wot switch, so my system starts spraying the second my foot hits WOT. Which means its the same as just mashing the gas without nitrous, only adding another 75 hp. The only ones who say that a 75 shot is gonna blow you up either have never touched nitrous outside of a dentists office, or have had an unusual circumstance take the lives of their motors.

Edit* NOS systems are nothing special, and the most rudamentary, the ZEX wet system is safe as hell, but you if you ever want to change something around it gets *****y, and the solenoids arent the strongest. No experence with venom, or edelbrock, but the edelbrock kits are made by NOS, so that would be all I need to know on that one. I have a NX kit with upgraded solenoids, and its awsome, I only have a single fogger EFI kit and with the solenoids I have I can jet up to a 200 shot. Dont ask, the kit came off a ford v8.

 

50 Shot is generally safe on most car but thats the limit..

you probaly could go higher if you have built internals... but you have to realize that you have to be tuned for it.. running gt35r with high boost already increases the compression ratio dramatically and on top of that even more with nitrious.. if your car run too lean because your not tuned for it... something is going to go...

run Wet nitrious system to be safer..

 

This guy actually understands what is going on, to a certain extent. Another thing to take into account is, with a dry system, all you are spraying in in nitrous, no fuel through the fogger. With this you need to tune in the ECU, and your off the bottle performance is going to blow because you will be crazy rich. With a wet system, you add fuel, so it is actually unnessacary to change any fuel maps to make sure it dosent lean out. You just tune your car for the maximum horsepower its going to make off the bottle, then chose the amount of HP you want to gain from spray. Say a 75 shot, NX calls for a #45 nitrous pill, and a #30 fuel pill. I would get the pills numbered #43, #44,#45,#46,#47, as well as #29,#30,#31,and #32, and jump on a dyno or buy a wideband to go along with it (always a good idea to have a wideband for nitrous, as well as EGT). Then you go to the dyno, and put in the nitrous jet they reccomended, and the largest fuel jet you bought, in this case a #32. This should yelid an extremly rich condition, which is never a problem. Then you step the fuel one step leaner. Until you get in the general location you want your AFR's. The nitrous jets are more sensitive to change, so you can then fine tune your air fuel ratios buy raising or lowering the nitrous jet. This is the best way to tune nitrous up to a 100 shot, past that you actually need to start adjusting in the ECU, because then you need to get more in depth to your timing and whatnot. Plus spraying more than 100, you really are saying your not to interested in off the bottle performance.

 

N20 is NOT a fuel, it's 2 parts nitrogen to 1 part oxygen, considering air is like 16% oxygen, it's like twice as oxygen rich as normal air. Oxygen supports combustion, it doesnt fuel it. Add to this the fact that it's in a compressed and liquid state you have a cold dense charge of air, and if you know the very basics of a motor you know that it's nothing but air, fuel, and spark.

 

Last week we had an turbo eclipse with the 4G63 running 150shot...it wasn't tuned for it and blew a hole the size of baseball on the back of the block...