After having Chad at Greenlight tune my car he advised me that my A/F was kinda rich on the nitrous runs. 10.5:1 A/F. He suggested going a jet smaller on the fuel. I have a Nitrous Outlet TB plate and the recommended jetting size for a 200 shot is 78N 46F. I have a 41 jet, but think that might be too small. Am I correct? Is there a 45 jet made for the NX kit?

Any other opinions are welcomed, and mods in sig if you need to know.

Thanks.

 

That's the beauty of a wet kit. They should have any jet you want. I agree that you are way too rich right now. Take small steps, but I imagine you will end up with a 43 fuel jet.

 

I would try a 42 jet first before going to the 41 size. JMHO.

 

Yea maybe try a 44 or a 43.

 

Here is a spreadsheet I made from some info I got from Doc

It calculates Nitrous AFR for optimum AFR (according to Engine Management:Advanced tuning by Greg Banish 2007)

Enter the Black Text Info, the red is autocalculated.

Beers Spreadsheet

Guessing you should be 11.0-11.1 for about 650 RWHP on spray (if you trust Mr. Banish).

 

bottle pressure on those runs?

 

Pressure was 1000psi

Thanks for the replies!

 

Thanks, but the spreadsheet isn't loading for me.

 

Forgive my ignorance but are you saying that our optimum AFR's should be dependant on the size shot we use?

I can't load that spreadsheet either.

 

Right Click save as, its an Excel sheet.

From what Greg Banish is putting out yes.

Here is the formula if the sheet don't work (works for me and I am in the middle of the Indian Ocean)

AFR for Nitrous = {(HP NA/Nitrous HP) * Maximum Brake Torque AFR}+{N20 Shot Size/Nitrous HP)*7}

So
AFR in my case...
417 RWHP NA
On a 150 Shot 567 RWHP
150 shot
Maximum Brake torque AFR say about 12.8

{(417/567)*12.8} + {(150/567)*7}

(.73544*12.8) + (.2645*7)

9.413 + 1.852

AFR = 11.265

You are pretty much taking the % of where the HP source is:
One is NA
the other is the Nitrous.

and Multiplying it by the Optimum AFR for that source
NA is 12.8 to say 13.1
Nitrous to Gas is 7 (according to Greg Banish's Book)
then ya add em.

 

Mine calculated that way works out to 11.06 which just sounds very rich - even though I am currently at 10.3 which are what the stock ZEX jets give you without playing with fuel jet sizes.

Thanks for the lesson though.

 

Any chance you're running a dedicated cell? If so, you could drop the fuel pressure a hair

 

No dedicated cell.

 

Looks like you'd better buy a handful of jets then.

 

ahhhh Banish is back? AKA Mr KaBoom

 

LOL. I have a handful of jets, just none from 45-43.

 

Beer do you think that spreadsheet is a bit on the rich side? It seems legit on the numbers and how they came about but just seems to be a little conservative on the rich side. How accurate would it be with stalled autos?

 

Is there a story there?

I plan on using it in May for tuning my system.

Banish is not the Wizard of NOS guy is he? (I have seen the wizard is a loon).

Doc professionally tunes cars in Jax and is an axid COS 5 Nitrous user, so being he pointed me in towards the formula, I am satisfied it good info.

 

What are you shooting for 11.0 11.5?

You could lower the bottle pressure to ~800 and try the 41 then if its still rich up the bottle pressure.

I think a 41 at 900psi will be close or a 42/43 at 1000 1 jet size is a verry small change.

What octane are you using?

 

110 octane. I'm at 11.5:1 compression which is part of the reason for the 110.