I have a 2000 GSR with a JRSC and all the guys at my mechanic, and my dyno tuners want me to run a very small shot of nitrous to cool the intake charge, like a 15 shot. A guy at the dyno has a dry NOS kit for 200 bucks. He wants me to run the dry kit, but the guy at my mechanic wants me to run a wet kit. The guy saying run the dry says for that amount of nitrous I will barely need any more fuel, and the IAT sensor in the manifold will sense the colder air coming in, and dump more fuel into the cylinders, therefor compensating for the nitrous. Which way would you go? Wet or dry?
gmoore

 

I responded to your PM as well in more detail, but in terms of wet vs dry, I say dry. I wouldnt be worried about the fuel through the blower as people sometimes speculate it may be a problem...I just prefer dry due to the simplicity vs wet with these small shot setups.

 

Who makes a 15 shot? The only one I know is Venom.

It depends on your setup whether dry or wet. If you have a rising FPR I would go wet becuase your fuel pressure is already high enough.

GSR + NOS + JRSC = risky without the proper preqautions like fuel management and built motor.

I think a wiser choice would be wetter that JR sells. In fact, if it drops the combustion temperatures like claimed, you probably come close to the gain from a 15 shot.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Mac8008 &raquo;</TD></TR><TR><TD CLASS="quote">
It depends on your setup whether dry or wet. If you have a rising FPR I would go wet becuase your fuel pressure is already high enough.

I think a wiser choice would be wetter that JR sells. In fact, if it drops the combustion temperatures like claimed, you probably come close to the gain from a 15 shot.</TD></TR></TABLE>

No, I definatly wouldnt see the gains of n2o with water injection, if I spray 15, I should see almost 25whp from the cooling effect. Are you saying I should go wet because the dry would cause me to run an even higher psi of fuel.

Newbie to n2o question- Does a dry raise fuel pressure to compensate for n2o? And does a wet kit kill the injectors and inject all your fuel through the nozzle? If not, where does it get its fuel from?
gmoore

 

Good point about him maxing out his injectors...the JR FMU is 5:1, so right now he should be OK in terms of FP, although he is asking for it with all these mickey mouse ways of adding fuel. You will have to make sure your mechanic is watching your fuel pressure carefully when installing the kit and playing with the settings.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by newgsrdriver &raquo;</TD></TR><TR><TD CLASS="quote">Good point about him maxing out his injectors...the JR FMU is 5:1, so right now he should be OK in terms of FP, although he is asking for it with all these mickey mouse ways of adding fuel. You will have to make sure your mechanic is watching your fuel pressure carefully when installing the kit and playing with the settings.</TD></TR></TABLE>

I suggested that I go to Prelude injectors before we tuned. And right now I have a 12:1 Vortech SFMU. My mechanic will only install the kit, I will not spray until we have it on the dyno, at which I will spend a good two to three hours on.

Im still not positive on how the wet kits get their fuel....Can someone explain? Is the fuel that is added with the nitrous the only fuel that is going into the engine? Or is it added in congunction with the fuel from the injectors?
gmoore

 

It is added in conjunction.

If you knew your FP's now, you could calculate an approximate FP with nitrous based on how much FP is raised under the desired shot.

IE find your FP now and find how much it will be raised with the nitrous @ a 15 shot.

 

It idles right now at 40psi, but thats because I have been throwing CEL 45 (too lean) so we have been richening it until we dont anymore, which is odd, because it was dyno tuned before we started throwing the code. How would I out how much the pressure would be raised with a 15? And why is having a high FP a problem? Because we may max out the injectors?
gmoore

 

Youre going to want to know your FPs under boost, as thats when it would be increased even more when nitrous is added. Im not sure how to find out how much FP is raised...maybe someone here knows with a similar setup, or your tuner can tell you.

The higher the FP the more fuel your injectors are pushing at their duty cycle. If their duty cycle is already high, which Im sure it is, say 90%, then they are open 90% of the time. A higher fuel pressure, we'll say 100PSI (which is too high) would mean during that 90% of time theyre open, more fuel is being forced out of them. If the injector stays half open or doesnt open as quick as it should (keep in mind they are mechanical and with a high duty cycle they are forced to open and close quicker than usual), thats MORE fuel that isnt getting delivered than would be if FPs were say 60. So you wont just run a "little lean"...that half second of not operating correctly can cost you a serious lack of fuel, which as everyone knows is the kiss of death.

Not to mention, your hoses can only take so much pressure, although I assume if youre running an FP with enough pressure to blow a hose, youre probably already history

 

Hmm, so your saying I need bigger injectors, and possibly SS lines? Would Prelude injectors be enough? And they clip right in correct?
gmoore

 

when you run a higher fuel press it wears out your injectors...its like having a small hose running at full blast vs having a bigger hose running at medium capacity...it just makes more sense to have the bigger hose and be able to deliver the fuel 100% of the time at a lower fuel press...when you run smaller injectors you risk not having enough pressure from your fuel pump to push the sufficent amount of fuel...then youll run lean...fmu's up the fuel press a lot...thats why on many turbo apps youll see people switch to dsm 450's and adjust the fuel amt back to stock level and run a different FMU vs the 12:1 more like a 7 or 8:1...

A wet n20 setup uses a sylenoid to add fuel...it would be added at whatever pressure your running currently...its just a t of the current line i believe and its controlled by that sylenoid...

a dry setup uses your current setup to add the fuel....sometimes your fuel system cant handle the extra need for fuel and will run lean...this is why many prefer wet setups vs dry.....by in your case id run w/ a dry setup just because the fuel thru the rotors will wash away some of the oils...causing your rotors to prematurely wear...

my recomendations are to pick up some bigger injectors, a fpr, a high flow fuel pump (to make sure youll have the desired press 100% of the time, altho you prob already have one for the jrsc) and a lower disk ratio fmu (by calcing out your current fuel flow rate..in lbs/min) then you can adjust your actaul fuel flow by adjusting the fuel press via the fpr...and your boost dependent fmu increase in fuel will be downline of your fpr and what not to add for the boost...

running a setup like that youll be able to run a stock idle w/o running to rich like many fmu setups that blwo smoke from the start because they are running really rich

 

Nono, not any new lines...if you need new lines, your setup is either beyond my comprehension or in big big trouble. You dont want high FPs, thats the idea...not good.

Bigger injectors is a possibility, but you will need some way to control them, IE AFC, Hondata, AEM, SMC, etc. You can find out if you need bigger injectors when you analyze the FP situation. I dont remember if youre at 6PSI or 8...I recall its 8, and if so, then yes, I would imagine bigger injectors will be necessary.

 

Ok, would Prelude injectors work? Or would they not be enough. Heres an idea....If I ran a wet kit, could I tee the fuel line from the return line of the rail, to the FMU, so that as boost was raised, it would raise the pressure to the rail, along with the pressure to the nozzle....Good idea?
gmoore