N20/Fuel jet sizes [Archive] - Turbo Mopar Forums

contraption22

10-08-2008, 08:37 AM

Those who know, please post jet sizes for various nitrous shots.

Thanks!

I'll stick it for reference.

shadow88

10-08-2008, 11:01 AM

Directly from Zin's PM to me a while ago.

standard jetting/HP will be: 40HP, 34N/18F; 50HP 37N/22F; 60HP 39/24; 70HP 41/26; 80HP 43/28; 100HP 46/30; 125HP 52/33; 150HP 61/38.

These are for N/A engines and you should be aware of the fuel jetting as every car is different and fuel pressures vary alot. I found I needed alot larger fuel jetting.

OnLooker

10-08-2008, 11:18 AM

gasketmaster

10-08-2008, 12:07 PM

You should jet according to your base fuel pressure setting ;)

Start out a bit fat and use a wideband :thumb:

Here's a handy calculator :)

http://www.robietherobot.com/NitrousJetCalculator.htm

contraption22

10-08-2008, 12:39 PM

The jetting is based off fuel pressure so with the reference reg it will change. Dynotunenitrous.com has a nice jet calc if you know the fuel pressure you will be running. Problem with running nitrous on a turbo car, if you start spraying it early before you are at your max boost it will be lean. If you spray it the whole run you might be better off setting up another regulator for just the nitrous.

This is incorrect. As boost rises, so does fuel pressure. So is your base fuel pressure is 55psi, the fuel pressure will remain 55 + boost pressure, so your fuel volume thru the jet should remain constant troughout the boost curve.

OnLooker

10-08-2008, 03:29 PM

OK, scratch that. I had my setup on a log intake and was spraying before the turbo. That calc still worked good for picking jets though.

Ondonti

10-27-2008, 01:31 AM

wow I just realized from this that nitrous and rising rate regulators are not friends.

contraption22

10-27-2008, 10:56 AM

wow I just realized from this that nitrous and rising rate regulators are not friends.

Yup, because if your fuel pressure rises exponentially in relation to your boost pressure, your a/f is going to get richer and richer.

Reeves

08-24-2009, 06:13 PM

The jetting is based off fuel pressure so with the reference reg it will change. Dynotunenitrous.com has a nice jet calc if you know the fuel pressure you will be running. Problem with running nitrous on a turbo car, if you start spraying it early before you are at your max boost it will be lean. If you spray it the whole run you might be better off setting up another regulator for just the nitrous.

Is there a chart out there that has jet size = x amount of HP?

Are the numbers on NOS jets the hole size? Example NOS jet 035 = 0.035" ?

Gaboon

08-24-2009, 06:49 PM

Is there a chart out there that has jet size = x amount of HP?

Are the numbers on NOS jets the hole size? Example NOS jet 035 = 0.035" ?

Someone posted this link http://www.robietherobot.com/NitrousJetCalculator.htm before and it seems pretty acqurate.

To be on the safe side, I always jet rich on the fuel side at first and work my way down.

Oh and have fun you crazy kid.

Gaboon

08-24-2009, 07:01 PM

Just for fun, and what my jetting will be next trip to the track.:thumb:

The Fuel jet size should be 0.687" or 17.445mm

A Nitrous jet size of 1.25" or 31.75mm should produce:
70564.38 HP with 1 port(s)

Actual HP to the wheels: 59979.72 HP

zin

08-24-2009, 08:50 PM

Is there a chart out there that has jet size = x amount of HP?

Are the numbers on NOS jets the hole size? Example NOS jet 035 = 0.035" ?

Yes, the number on a NOS jet is the size in thousands of an inch. Somewhere I've got a chart that lists HP for a given size jet. For now I'll post the charts I have handy.

As for larger sizes, as are likely to be used in a single nozzle set-up, "stock" jetting is as follows:

HP - Nitrous - Fuel (@ 35-40PSI)
50 / 37 / 22
75 / 41 / 26
100 / 46 / 30
125 / 52 / 33
150 / 61 / 38

Since we typically run higher pressures, expect that you'll need to come down on the fuel jet to get it dialed in better, but start with these numbers to see how your engine will react, sometimes they really like the extra fuel, sometimes not, but it's better to have it and not need it, than need it and not have it!:nod:

The attached charts are mostly for direct port applications, one showing the HP the other shows how the fuel jet will change depending on the fuel pressure. Finally, the Word doc is what we send out with our flow tools. Hope you all enjoy!

Mike

Reeves

08-24-2009, 10:44 PM

Someone posted this link http://www.robietherobot.com/NitrousJetCalculator.htm before and it seems pretty acqurate.

To be on the safe side, I always jet rich on the fuel side at first and work my way down.

Oh and have fun you crazy kid.

I saw the link, which will be very handy, but I wanted to see if there was a chart out there that showed which jet to use for what HP level, and then I can see which fuel jet I'll need to match.

Yes, the number on a NOS jet is the size in thousands of an inch. Somewhere I've got a chart that lists HP for a given size jet. For now I'll post the charts I have handy.

As for larger sizes, as are likely to be used in a single nozzle set-up, "stock" jetting is as follows:

HP - Nitrous - Fuel (@ 35-40PSI)
50 / 37 / 22
75 / 41 / 26
100 / 46 / 30
125 / 52 / 33
150 / 61 / 38

Since we typically run higher pressures, expect that you'll need to come down on the fuel jet to get it dialed in better, but start with these numbers to see how your engine will react, sometimes they really like the extra fuel, sometimes not, but it's better to have it and not need it, than need it and not have it!:nod:

The attached charts are mostly for direct port applications, one showing the HP the other shows how the fuel jet will change depending on the fuel pressure. Finally, the Word doc is what we send out with our flow tools. Hope you all enjoy!

Mike

I had read somewhere that NOS jets were not in thousandths of an inch, so I just wanted to make sure.

Thanks for the info!

I'm going to make a spread sheet with HP per jet size and then fuel jet size based off fuel pressures.

zin

08-25-2009, 03:52 PM

I had read somewhere that NOS jets were not in thousandths of an inch, so I just wanted to make sure.

Glad I could help, if you want/need any other specific info, just let me know and I'll see if I can get it for you.

As a side-note on the NOS jets, the newest Stainless Steel jets are made a bit differently these days, back before NOS was sold ('99), they were brass and just drilled with whatever size drill (thousands), but after Holley "lost the rabbit" and couldn't build a good jet to save their lives, they out sourced them to a medical orifice manufacture that builds jets to a flow standard rather than a hole size, the net effect is a jet that is within 3% of it's target, regardless of the hole size. In practice, a 28 jet will still almost always be .028", but it could be slightly bigger or smaller, but it will still hit it's flow target, which is what is really important anyway. I have to say that the stainless NOS jets are the nicest jets that have ever been produced, by any manufacture! Heck, if they didn't mind the astronomical rejection rate, they could offer jets within .5% of a given target flow rate! Of course, none of us want to pay $50 a jet!

With all this said and done, most jets produced today are of fine quality, and would likely be in a +/- 5% range or better, but NOS is the only one that 100% flows their jets (it's part of the manufacturing process) and so can guarantee their accuracy.

Now, is it really that big a deal? On a direct port system? Yes. the more jets you have to deal with the greater the chance of tolerance stack-up and the problems that can bring, especially when trying to maximize a particular tune/hp level. Is it important in a single nozzle application? Not really. Stock tune-ups will have anywhere from 10-15% extra fuel already in the tune, so even if the nitrous was 5%+ and the fuel 5%-, it wouldn't be dangerous.

Clear as mud right?;)

Mike

contraption22

08-25-2009, 04:15 PM

Another plus with the SS NOS jets... the numbers are laser etched into the jets instead of stamped into it. I have a hard time reading alot of the old brass jets.

Reeves

08-25-2009, 04:40 PM

Glad I could help, if you want/need any other specific info, just let me know and I'll see if I can get it for you.

As a side-note on the NOS jets, the newest Stainless Steel jets are made a bit differently these days, back before NOS was sold ('99), they were brass and just drilled with whatever size drill (thousands), but after Holley "lost the rabbit" and couldn't build a good jet to save their lives, they out sourced them to a medical orifice manufacture that builds jets to a flow standard rather than a hole size, the net effect is a jet that is within 3% of it's target, regardless of the hole size. In practice, a 28 jet will still almost always be .028", but it could be slightly bigger or smaller, but it will still hit it's flow target, which is what is really important anyway. I have to say that the stainless NOS jets are the nicest jets that have ever been produced, by any manufacture! Heck, if they didn't mind the astronomical rejection rate, they could offer jets within .5% of a given target flow rate! Of course, none of us want to pay $50 a jet!

With all this said and done, most jets produced today are of fine quality, and would likely be in a +/- 5% range or better, but NOS is the only one that 100% flows their jets (it's part of the manufacturing process) and so can guarantee their accuracy.

Now, is it really that big a deal? On a direct port system? Yes. the more jets you have to deal with the greater the chance of tolerance stack-up and the problems that can bring, especially when trying to maximize a particular tune/hp level. Is it important in a single nozzle application? Not really. Stock tune-ups will have anywhere from 10-15% extra fuel already in the tune, so even if the nitrous was 5%+ and the fuel 5%-, it wouldn't be dangerous.

Clear as mud right?;)

Mike

AWESOME info! Thanks so much!

Another plus with the SS NOS jets... the numbers are laser etched into the jets instead of stamped into it. I have a hard time reading alot of the old brass jets.

I have both kinds of jets. I had many old brass ones from when I used a fuel cheater solenoid and fogger nozzle as a 5th injector. I purchased two more nozzles back then and they came in as the nickel plated (?) with laser etched or screen printed numbers. I never got around to using them before I went to alchol.

This nitrous kit I have that a friend is letting me borrow also has both kinds of jets.

Some of the numbers that are stamped on the brass ones are either not legible, or stamped off the edge of the jet so bad they are not legible.

I think where I was getting confused about NOS jets was that HOLLEY jets are not in thousandths of an inch. ??

zin

08-25-2009, 04:55 PM

Some of the numbers that are stamped on the brass ones are either not legible, or stamped off the edge of the jet so bad they are not legible.

I think where I was getting confused about NOS jets was that HOLLEY jets are not in thousandths of an inch. ??

If you have brass jets that don't look so hot and/or have illegible numbers, can them, those are the ones that Holley was loosing their mind while trying to reproduce the jets NOS had made for years, but Holley just couldn't quite get it, hence the new stainless jets. I wouldn't trust those as far as I could throw them!

In regards to the Holley jets, you are correct, you might notice there is a small table in the HP jetting chart that gives a rough cross reference from thousands and Holley jet sizes. A bit of trivia on the Holley jets, they are numbered by flow rates (what scale I don't know for sure), you also might notice there are a few different Holley numbers that have the same size hole. That is because in a carb, they could chamfer the inlet side and pick up flow without the need for a differently drilled jet. This is also why I'll never (by my choice anyway) use a Holley carb jet for flow testing or pressure setting as some old timers in Pro Mod will do. It's not that it can't work, it just isn't accurate to what you'd see going down the strip. I won't bore you with the details as to why, but I'll hazard a guess you all can figure that one out!

Mike

Reeves

08-26-2009, 08:51 AM

Here's a few pics of the preliminary install. I ordered a shorter hose from bottle to solenoid, and shorter hoses from solenoids to fogger nozzle.

Also ordered a telephone cord type momentary pushbutton (for steering wheel) and a blow down tube and racer safety valve

Anyone see any problems with the pics? Not a trick question, just want to know from nitrous junkies of any problems I might run into.

Pat

08-26-2009, 09:06 AM

just want to know from nitrous junkies of any problems I might run into.

Nice install, very clean. I especially like the solenoid bracket you made. The only thing I'd be careful of is if your nozzle is pointed up, it makes it a bit trickier to change jets (can drop them). If you have the nozzle pointed slightly down, you have gravity working to your advantage changing jets. Not a big deal at all, but something I picked up doing mine.

The only real problem I'd watch out for is cramping in your cheeks from the big freaking smile you're going to have on your face when you start using it.

contraption22

08-26-2009, 09:15 AM

The only problem i see is that you really should have two bottles. Big ones.

But I think it looks great!

You already mentioned the safety blow-down tube, you may want to consider an RPM window switch as a safety in case of bogging or traction issues. I would definitely get a WOT switch if you don't already have one.

Also make sure that the floor boards are reinforced with diamond plate, and also think about adding a MIS (manifold integrity sensor), that you can monitor with your laptop.

Reeves

08-26-2009, 10:02 AM

Nice install, very clean. I especially like the solenoid bracket you made.

Thanks. I'm pretty proud of that bracket...lol. Drew it up in CAD and had the guys here at work burn it out on the laser. Then I added the twist and retainer bend at home.

I'm going to add the twist and retainer bend to my drawing, then I should be able to get some made later.

The only thing I'd be careful of is if your nozzle is pointed up, it makes it a bit trickier to change jets (can drop them). If you have the nozzle pointed slightly down, you have gravity working to your advantage changing jets. Not a big deal at all, but something I picked up doing mine.

Yeah, I thought about that....but my dag-gone BOV is in the way if I try to use the existing holes (left over holes from alky kit). I'm planning to later make a new aluminum intercooler pipe there (then all my intercooler plumbing would be aluminum) and add a bung for the 1/16" npt fogger nozzle (currently I made a adapter to go from 1/8"npt to 1/16" npt) and add a HKS or other type of better BOV.

The only real problem I'd watch out for is cramping in your cheeks from the big freaking smile you're going to have on your face when you start using it.

I hope so! I only plan a little shot in 4th if I need it to beat the Honduh's! Last year I was the only qualifier without NOS.

The only problem i see is that you really should have two bottles. Big ones.

1 more problem.....I NEED THEM BY TONIGHT!!!

But I think it looks great!

You already mentioned the safety blow-down tube, you may want to consider an RPM window switch as a safety in case of bogging or traction issues. I would definitely get a WOT switch if you don't already have one.

I got a WOT switch that monitors the TPS voltage. It's adjustable for what voltage you consider WOT and then it closes a dry contact. Should work out ok and better IMO than a mechanical switch.

I do not have a RPM window switch, but I was thinking that with the wot and with a momentary push button on the steering wheel in series that I should have pretty good control of it?

Also make sure that the floor boards are reinforced with diamond plate, and also think about adding a MIS (manifold integrity sensor), that you can monitor with your laptop.

I have marked the boost gauge with a warning label past the 35psi mark that says "Danger to Manifold" I looked at it after I installed it and told it to shutup....

Also, I'm having a real hard time finding aluminum diamond plate that sparks on the ground. Where do you get that from?

contraption22

08-26-2009, 11:10 AM

Also, I'm having a real hard time finding aluminum diamond plate that sparks on the ground. Where do you get that from?

Talk to Harry at the Racer's Edge. He can hook you up. I used to sling parts for him.

Reeves

08-26-2009, 11:12 AM

Talk to Harry at the Racer's Edge. He can hook you up.

I called. He told me he's seen how I drive! :o

Told me I have a heavy foot and that I'll blow myself to pieces.... :o

contraption22

08-26-2009, 11:26 AM

Well I know this other guy you can talk to. His name is Hector. He's got a last name too, but he not pronouce it. He's going legit. Gonna try and get on the NIRA circuit.

zin

08-26-2009, 03:48 PM

Also make sure that the floor boards are reinforced with diamond plate, and also think about adding a MIS (manifold integrity sensor), that you can monitor with your laptop.

:lol::lol::lol:

I always cringe and laugh whenever I see that part!

Seriously though, if you mount the bottles to sheet-metal, be sure to have big body washers on the back-side to be sure it can't pull free/through. Other than that (and the blow-down already mentioned) it's looking very good!

Mike

badandy

08-26-2009, 04:07 PM

Man...Reeves, Mike...you guys are gonna get me fired! I'm at work laughing my --- off :lol:

Reeves? Question:

If you are the "mad scientist" how are you and the mad scientist gonna replace the piston rings you fried?

contraption22

08-26-2009, 04:12 PM

Reeves

08-26-2009, 04:39 PM

bakes

04-02-2011, 05:17 PM

Question on retarding timing as per hp level, most say 2 deg for every 50 hp added but it this a V8 # ,wouldn't a 4cyl be like 4 deg retard for 50 hp added because of 1/2 the cylinders twice the cylinder preasure??

I started a new tread as i tought this is going to side line this tread.
http://www.turbo-mopar.com/forums/showthread.php?57908-Nos-timging-retard-for-4-cly-per-hp-shot