CLyons0203

iTrader: (1)

Zex states that due to the 350Z's unusually high base fuel pressure (51 psi) they include fuel jets that are made specifically for the 350Z. Fuel pressure on a V6 engine on average is around 35-40 psi. With the 350Z's higher pressure wouldn't it require a slightly smaller Jet size than the universal V6 kit?

Fuel Jets for 350Z
19\55 shot - 26\75 shot - 28\100 shot

Universal Jets for V6 engines
17\55 shot - 21\75 shot - 26\100 shot

Nitrous Jets are the same on both

Looks like Zex increased the fuel jet size eventhough the fuel pressure is already high. Wouldnt this cause an overly rich condition?

3hree5ive0ero

iTrader: (95)

Your logic makes sense to me, so yeah it appears they did the opposite of what they said they were doing. Either way, go with the recommended jet sizes.

2bad240

iTrader: (6)

im not sure. i think all the companys rate them different.
nos rates theres at the crank.
im running a 36n/24f i was told thats a 75 at the crank. i gained 52hp at the wheels from it.

3hree5ive0ero

iTrader: (95)

^ While what you're saying may be true, it has nothing to do with what the thread's about.

2bad240

iTrader: (6)

just saying different companys rate them different. from what he says the zex uses a 26, the universal uses a 21. and my nos uses a 24. so its kinda hard to say if its gonna cause a rich situation. the jets could flow different. the solinoids could flow different. the nozzles could flow different.

denchan350gt

iTrader: (4)

I just got tuned for my Zex 100shot and my jets were 26F 46N and with the 26 my injectors were maxed out 105%.

I was told by my tuner to up my fuel jet to a 28 to get the 11.5 a/f right now I'm at 12.2 with the 26 jet I'm tuned using uprev.

I went by the chart on zex's site so I didn't know the VQ went by different jet sizes I bought my kit used.

Hopefully I will see what it can do on Feb 25th since my best N/A is 13.1 on street tires.

denchan350gt

iTrader: (4)

what kit do you have and are your tq numbers a secret? I'm just trying to compare. I went from 260hp to 318hp and 235tq to 340tq with a 100shot using the Zex kit.

I might make more once I up my fuel jet.

CLyons0203

iTrader: (1)

apples and oranges. Im not comparing the Zex to any other units.

CLyons0203

iTrader: (1)

I called Zex on the phone and spoke to their "technical person". He stated the jet chart is for the HR motor because only that motor has the higher fuel pressure. I told him he was wrong, same pressures. Then he said the jet chart is correct, but he did admit the jets should be smaller not larger and would look into what happened.

Dont forget that Zex overlooked the resistor and their 350Z nitrous plugs were a huge failure.

CLyons0203

iTrader: (1)

A few things:

Your current AFR of 12.2 is not that bad. Some say afr on spray should be the same as afr NA. Some say other wise.

Why are your injectors maxing out? your using a wet kit which adds the fuel. Are you trying to increase the duty cycle of the injections to compensate for nitrous? if so i wouldnt do that.

I like to let the injectors handle the NA power. And adjust my jets to control the AFR on nitrous. Running your injectors past 80-85% duty cycle will burn them out

Stock2Autocrozz

iTrader: (6)

Zex fuked me over bad man....do the work yourself, and never bother with their tech support/rant

denchan350gt

iTrader: (4)

I have a nitrous map and the tune has a target of 11.5 but there is not enough fuel to get it there with the 26 jet.

Last week another car was there without a tune and it showed the same thing when using the same jet sizes 12.2afr. He plans on changing his fuel jet also.

He went from a 75 to 100shot on the 75jets his afr was perfect.

CLyons0203

iTrader: (1)

Was the other car running a Zex kit also? Did they use the 350Z reccomended jets or the universal size jets? Bottle pressure?

I assume your nitrous map is basically your Na map but less timing and different target afr?

denchan350gt

iTrader: (4)

He has a NX kit using the universal sizes. My pressure was 950 his was 1050 and yes my tune is my na tune with timing removed and a target a/f.

My tuner told me the same thing about adjusting the jets for the ecu to compensate.

3hree5ive0ero

iTrader: (95)

I've never seen so much reading comprehension fail in a thread.

This thread is about how ZEX wrote that due to the higher fuel pressure for the 350Zs, they "upped" the jet size to compensate. If you knew basic chemistry or even math, you'd know that with higher pressure, you'd have to reduce the volume (the jet size) to achieve the same end result when comparing to a car with lower fuel pressure. That's what this thread about. Either way, it sounds like the OP got it addressed with the ZEX reps.



I have the dynotune kit (my info is all over this nitrous forum, but I have a specific thread for my set up).

My N/A numbers are old, but it should be very similar to what I'm making now as only the exhaust changed (either from TopSpeed Pro-1 or Fujitsubo Super Ti to APS 2.5" TD with x-pipe.. and I'm on my 5th or 6th test pipes).

My nitrous numbers are just plain messed up. I've been on the dyno a couple of times with spray, but I always had problems on it. First time, the damn dyno couldn't read my tach and my tq numbers didn't show (well, it said that I put down 211 wtq with spray, rofl). Second time around, I was on low bottle pressure and the damn dyno operator left my VDC on and sprayed, resulting in them wasting my nitrous that I was already low on and VDC kicking in (noobs @ Cobb at Plano, TX). Anyway, the problems on the dyno is why I think my HP numbers are low and why I don't even have the TQ numbers.


BTW, you use your fuel jets to "basic tune" your AFR on a wet system. Then you get a real tune to fine tune it. And don't use "universal" sizes (no need to explain this further).

denchan350gt

iTrader: (4)

I understand what this thread is about I was just stating that with the sizes on their chart for a 100shot using the zex kit caused my a/f to lean out a little from my target. I also didn't know the sizes are different for a vq which to me doesn't make sense with the higher fuel pressure.

I'm only going by what the dyno and my tuner is telling me I will find out when I go back with a higher jet or lower jet which I both have now to fine tune.

Any plans on going to the track this year and I knew your kit was dynotune or NX just couldn't remember which one.

3hree5ive0ero

iTrader: (95)

I guess you can start and see where your AFR is using the universal sizes, but I wouldn't trust it without verifying the AFR. I checked mine on the dyno (which is what I cared about, not the other numbers) and mine looked all right. I never got a tune, but that definitely would have helped. If your AFR is low 12s on the juice, I'd up the jet size 1 step (whatever is the next number) and see where you end up with that. Shoot for high 11s, or at least that's what I'd do.

I haven't been to the drag strip since my crappy 12.2@107. I'm in Chicago now and my ET Streets are back in Dallas, so I probably won't be visiting the drag strip any time soon. I really want to make a 11 sec pass, though, so I may bring up my slicks next time I drive down to TX. What's your mileage at? I think you have just as high mileage or higher on the odometer than me (120K), which is what scares me the most when spraying untuned.

On a side note, I'm glad that more people are becoming interested in spraying their VQs. I just hope it's not another "wave" like it's been in the past.

MikeEwithTheZ

iTrader: (11)

If you make the mixture richer with the same amount of nitrous you are not going to make any more power

When I was on spray ages ago with the standard zex kit(the 350z kit wasn't out at the time) i put down 255whp w/ bolt-on's and 350whp with the 100 shot and some tuning on a mustang dyno. I used the 26 fuel jet with 12.2 AFR's

Are you running at least one step colder plugs?

3hree5ive0ero

iTrader: (95)

^ I agree. You make more power the leaner you go, but the leaner you go the higher your chances of going BOOM.

denchan350gt

iTrader: (4)

I am using 1 step colder plugs my 12.2 afr was read on the dyno so it was recommended to up the jet size. The next one up is a 28. I was told I may make more power earlier because it didn't hit as hard at first due to the lack of fuel.