Playing with Jet sizes for better AFR's?
Thread Starter
12 Second Club
Joined: Sep 2008
Posts: 25
Likes: 0
From: Grand Haven,MI
Playing with Jet sizes for better AFR's? Hey guys just trying to get some info. I have a Zex fogger kit and i have the 175 jets in now and the AFR's hit the basement at around 9.5:1, WAY TO RICH. I don't want to risk lifting a ring or washing out the bearings. So what im wondering is if it might be ok to run a smaller fuel jet and compinsate to try and get the AFR's at a more optimal 11.5-12.0 range? ANY help would be greatly appreciated!!
Yes this is how you dial in a nitrous system. A more accurate way to dial in your tune is to read the plugs. For mor info on this look around a bit and you will get all the info you need around here.
Thats what im going through and 2 different tuners told me you need to adjust A/F by swapping fuel jets. My situation is much worse i need that initial tune to get me close and then i can adjust with my fuel jets since im coming from a dry shot to a wet shot.
I would also verify that you have everything running right in the first place, and also that the plugs verify the wideband reading.
Recommended jetting is always on the rich side but down in the single digits will hurt parts just as bad as if not worse than being lean. If the plugs concur with the wideband, I would probably do a consumption test just to be safe and make sure your are spraying the proper amount of nitrous.
If everything is in working order, You probably need to go down 3-4 jet sizes and make a short hit and see if that gets you back in the ballpark.
One last thing to add since you are clearly new ( Nothing wrong with that.) Be VERY careful with timing while you are leaning it out this much. If that plug even has a hint of a timing mark on it, you have to pull timing as you lean this out basically 3 full points.
Recommended jetting is always on the rich side but down in the single digits will hurt parts just as bad as if not worse than being lean. If the plugs concur with the wideband, I would probably do a consumption test just to be safe and make sure your are spraying the proper amount of nitrous.
If everything is in working order, You probably need to go down 3-4 jet sizes and make a short hit and see if that gets you back in the ballpark.
One last thing to add since you are clearly new ( Nothing wrong with that.) Be VERY careful with timing while you are leaning it out this much. If that plug even has a hint of a timing mark on it, you have to pull timing as you lean this out basically 3 full points.
Thread Starter
12 Second Club
Joined: Sep 2008
Posts: 25
Likes: 0
From: Grand Haven,MI
Yea my tune is right on! Just when i spray it, it falls to single digits and wideband corresponds with the one the tuner used as well. timing is very very conservative as well so not to worried there. Ill go down two jet sizes for now and do a quick hit and see where the wideband puts me and then read the plugs as well. Thank you all for the info it is VERY much appreciated!!!
TECH Apprentice
Joined: Nov 2009
Posts: 367
Likes: 0
From: Kentucky
Back to the reading plugs for a sec. Does the type of fuel you are using play any role in how accurate reading the plugs will be? I keep hearing from people that it doesn't work as well as it use to with the new fuels (93 pump gas)because of the modern additives. So is race gas easier to do it with?
Trending Topics
Just make sure everything is working correctly. I ran very rich one time on a new setup, swapped a smaller fuel jet in and still ran rich. Pulled the nitrous jet and a piece of rubber was clogging it so it was never seeing any nitrous.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine
Verdad Gallardo
7 Most Reliable High-Performance Engines GM Has Ever Built
Verdad Gallardo
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin
Verdad Gallardo
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Are you sure your wideband is correct?
What do the plugs look like that's the main thing, then use the wideband as a reference to what the plugs look like at a given afr reading.
What do the plugs look like that's the main thing, then use the wideband as a reference to what the plugs look like at a given afr reading.
Thread Starter
12 Second Club
Joined: Sep 2008
Posts: 25
Likes: 0
From: Grand Haven,MI
Yes the wide-band is spot on. The plugs looked great. Changed them out Friday made some pulls and re-checked them and they also looked great no blackening or fouling. Nitrous jet from zex im using is .083 and fuel is .034.
What does "great" mean?
You made a few runs and then pulled the plugs? If so they told you nothing.
When we say read the plugs, it means a brand new set of plugs, no drive time, make a pass and shut it down at the top end and pull them. You cant drive on them and still learn anything from them.
Spraying an .083 jet and tuning the way you are is asking for hurt parts. You need to start completely over with the recommended jetting for 100hp and learn what your doing. I do not mean this rude or condescending I just do not want you to hurt the motor. There is a lot of good information on this site and plenty of people to ask for help. Again, you should do both and slow down.
You will go faster with less hurt parts this way.
For starters, answer these.
What plug and gap?
How much total timing and timing pulled?
How are you adding fuel, what fuel, and what pressure?
Thread Starter
12 Second Club
Joined: Sep 2008
Posts: 25
Likes: 0
From: Grand Haven,MI
Im just going by what the Zex website says for the fuel Nitrous jet sizing. Im running NGK TR6 plugs on .045 gap. Not sure on timing but my tuner said the timing was fine for spraying it... I pull fuel from the shrader valve to the kit on 60 lbs of fuel pressure at the rail. I only run Shell 93 fuel in it as well. Im still pretty new to this and dont wanna blow up a $10,xxx motor.... I truly appreciate all the help from all of you!!!! and as far as the wide band it reads exactly what my tuners did in each bank... so i know thats good. Plugs looked good i made 2 pull and pulled them and checked them, there was no fouling timing marks or detonation what so ever they looked like i had just put them in... I cant wait to get my twin turbo set up done and get off this bottle.................
^ Sorry, accidentally hit the delete button, instead of edit.
Got pics of the plugs? If you continue to run a .083 nitrous jet on TR6 plugs, you'll probably tear some **** up. Ditch the tr6s and run a much colder plug on that size shot, like b9efs (#1085).. You need to know where your timing is and I would close up the plug gap also. Your tuner should know these things. Looks like you might wanna look elsewhere for tuning.
Got pics of the plugs? If you continue to run a .083 nitrous jet on TR6 plugs, you'll probably tear some **** up. Ditch the tr6s and run a much colder plug on that size shot, like b9efs (#1085).. You need to know where your timing is and I would close up the plug gap also. Your tuner should know these things. Looks like you might wanna look elsewhere for tuning.
Thread Starter
12 Second Club
Joined: Sep 2008
Posts: 25
Likes: 0
From: Grand Haven,MI
He knows i just cant get ahold of him. Ill get all the info tmro and re-post. I still want to get off the bottle and get my turbo set up done either way! Thanks for all the help everyone but the bottle is staying off for now!