nitrous

I'm got mine spraying into the elbow that the lower innercooler tube connects to. Right before it goes into the intake manifold.
 
nickleman60 said:
where's the best place to plum your nozzle on the intake? i want to use a wet system,55 to 75 shot.


.....you've been talking to John haven't you,lol,he swears by the wet system rather than a dry one.Jason runs a dry system...a wet system plumbs differently........did you get the diff. changed over today?
z
 
Z I don't see why you couldn't spary a wet system in the same place. I'm with you I wouldn't bother with a wet shot for only a 55-75 shot. I'd leave that for the 125 or bigger.
 
i didn't get the rearend changed,spent the day with my lady.maybe this week i'll get a chance.as far as the nitous goes,i thought with a dry system you have to do something to increase fuel pressure but with a wet system you can plum it and go.
 
i've been studying the zex systems and i like the way they work,but if you read the difference between the wet and dry kits they say the wet kits are great for turbocharged and supercharged applications.the dry kits say for n/a applications so that's why i'm leaning towards a wet kit
 
To each his own. With the wet shot you will not be able to spray it until the RPM's come up some on the motor. The Dry you can spray as you're leaving the line. The sooner you can spray it the better with these heavy cars. My 55hp dry shot was good for about half a second in the 1/4 mile on my car.
 
Let me chime in since I've done lots of reading on the different kits.
You may also read info from Dave Neibert, as he's got plenty of experience with N2O on a SC. So I would search posts for nitrous with Dave Neibert...

First off, the dry nitous kit, NOS brand or ZEX will increase fuel pressure to the FPR (fuel pressure regualtor). This is the same thing that happens with the supercharger. The boost pressure leans on the FPR for more fuel during boost. The problem with the dry kit is that you may be close to maxing out the injectors. I've read somewhere here that once the fuel pressure gets past 50 PSI, the the injectors may freeze up; stock pressure is about 40 lbs and increases about pound for pound with boost. It may be like 39lbs, but you get the idea. So with the nitrous and boost increasing fuel pressure, it may get close ot the limit of the injectors.

I haven't delt with Zex, but if you call the NOS tech folks, they will tell you not to use a dry kit on a forced induction app... I know people are using the dry setup, but according to the NOS folks, they are runnig them on the edge of injector failure...

Now the wet vs dry setup in regards to what RPM is required, the N/A guys must be at a certain RPM (3000???) for the wet setup because the fuel can drop out and casue a nitrous backfire at low RPM. To my understanding, in a turbo/blown application, this is a non-issue, as the boost doesn't allow the fuel to dropout at low RPM as it would in a N/A application, and for smaller shots, say below 100, a nitrous backfire is alot less likely anyways. The wet kit is also more tunable as well.

I know Dave Neibert uses a 100 shot in his 11 second SC, and I'm pretty sure he hits it off the line as well, but you may want to check with him to get details of his setup.

In any case with nitorus, a wideband O2 setup is almost a must to make sure you aren't leaning out.

AS for nozle location, dry vs wet don't matter; what matters is that if it is plumbed in the lower IC tube, (before the ACT sensor) the computer will advance timing due to the reduced temps. If plumbed in the return plenum after the sensor, the computer will ignore the shot, thereby NOT advancing timing.

The NOS systems general rule of thumb is to reduce timing 2 degrees per 50 HP of nitrous. IIRC, the eec will pull a max of 4 degrees of timing based on ACT temps, and a warmed up SC at WOT will surely be retarded the full 4 degrees at WOT. So if you add nitrous before the ACT, the computer will probably advance the timing those 4 degrees instantly, which may be bad, particularly on a 100 shot where timing should be retarded 4 degrees.

So the general rule, is to plumb it into the return plenum, after the ACT sensor to keep the timing correct.

Also, pulling the octane plug will retard timing by 4 degrees also, so if you think your motor is up to a 100HP shot, pulling the octane plug should retard the timing the required 4 degrees.

I would not run nitrous without a wideband O2 meter, and I would start small, say 50HP and go form there. This is what I plan to do in the next month or so as a matter of fact. I'm gonna see if my current old motor will hold up to a well-tuned 100 shot :D

Anyways, there's my 2 cents.
 
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You are probaly right about a boosted car not needing to wait for a certain RPM before spraying a wet shot. As far as maxing out the injectors you will problay be safe with a 50 shot. My car made 262 rwhp with a couple bolt ons and the 55 shot and was running rich at 10.5 to 1 AF with the stock 36lb injectors. Now I know my car was running lean without nitrous when it made 274 rwhp a couple months ago but with my new 60lb injectors I don't think I'll go lean with the 55 or 75 shot. Also don't forget that if you want to go with a dry shot bigger than 50 you are going to need to upgrade your fuel pump. Might want to upgrade it even if you are planning on just a 50 shot.
 
thanks for the info.both of you seem to have alot of knowledge about nitrous.i been thinking about adding nitrous for a few months now and i'm still taking in alot of info before i make the plunge.
 
I'd read plenty more and make an informaed decision, and think about the possibility of what you may want to do down the road also.

The fuel pump is a great point, the 255 FI unit is aboutt he same price as the 190 and 255, so I'd go with it...

I'd also say the 55 dry shot is OK, so long as you don't want to go too much higher.

I know "fastsc92" ran mid 12s on the zex dry 75HP kit, but he knows how to tune for it, and monitors with a PLX wideband and datalogs things to make sure all is well with the AFR.
 
Read this article by Wayne Ing about using nitrous on an SC. It covers pretty much any questions you might have and is very accurate.

http://www.sccoa.com/sccoo/Faq/nitrousoxide.htm

I use a NOS wet system and like it because it's much more tuneable than the dry one. For example, when trying to use the reccomended nozzels for a 100 hp, the fuel was way to rich, so I dropped down to a 75 hp fuel and kept the 100 hp nitrous nozzel.

I use a multi channel chip with a program just for nitrous, that his a higher rev limiter and 5 degrees less timing above 3000 rpms. My nitrous system also includes a fuel pressure safety switch (pressure must be at least 50 psi to activate solenoids). Initially I had an RPM window switch that turned on the system at 3000 rpms and turned it off at 6000. It proved to be a pain in the azz, so I removed it. If your running a 5 speed it probably good to have just in case you miss a shift, but with an automatic I don't think it's needed.

Get the bottle heater for the nitrous bottle to maintain a constant pressure. The NX heater is the best because it uses a pressure transducer to regulate the heater, where most others try to maintain a specific temp. Depending on the volume of nitrous in the bottle, the pressure will vary a great deal even when kept at the same temp.

DO NOT run the nitrous system until you have tested and verified your A/F ratio is correct on a dyno with a wide band o2.

David

PS: For 50-75 HP I would use the Zex dry system.
 
Frozen Injectors?

sizemoremk said:
I've read somewhere here that once the fuel pressure gets past 50 PSI, the the injectors may freeze up.
What's going to make the injectors frozen?

confused 68COUGAR
 
68COUGAR said:
What's going to make the injectors frozen?

confused 68COUGAR

The post I was talking about is here (post 10):
http://www.sccoa.com/forums/showthread.php?t=47855&highlight=nitrous


I didn't mean that literally, I ment they would fail to inject, or so I read :D This is the same reason the guy at NOS Systems said not to use dry on FI apps...

Maybe not word for word, but the same point...

But like Neibert says, if I was gonna stick with 50-70 horses, I'd stick with the dry... I originally got the dry kit, then went wet after some correspondance with mr. Neibert and the guys at NOS. This also allows me to run 100+ when I get bawls to try it ;)
 
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Agreed....if going over 75 HP the wet system would probably be a better choice. You also need to consider your injector size. I've got 50# injectors and doubt I could supply enough fuel thru the injectors to support much more than a 100 HP shot. With a wet system that isn't a problem....I could go as high as 150 and still have enough fuel getting to the injectors run the motor at a safe A/F ratio.

David
 
i have a 94'sc with 36lb injectors,76mm maf,75mm tb it's an automatic. could i run a 55/75 wet shot without changing anything?
 
nickleman60 said:
i have a 94'sc with 36lb injectors,76mm maf,75mm tb it's an automatic. could i run a 55/75 wet shot without changing anything?

You could do wet or dry at that power level. It would be safer to reduce ignition timing 2 degrees, but I don't really think it's going to break anything if you don't. You may also need to change the plugs as mentioned in the article I linked.

David
 
what i want to know is where do you place the nozzle for a wet kit? Ive read put it in the lower i/c pipe as well but how close to the inlet for the intake can you get it there?
 
I've got my nozzel located in the lower IC tube about 18" before the ACT sensor. Since it's a MP FMIC the tube was easy to remove and drill for the nozzel.

If doing it on a car with stock IC tubes, I would locate the nozzel just after the ACT sensor on the return plenum. Mine has a difusser welded in the plenum so it won't work there.

David
 
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