Nitrous Tuning and AFR
Thread Starter
Teching In
Joined: Nov 2014
Posts: 3
Likes: 0
From: Iowa
Nitrous Tuning and AFR Looking for some Nitrous tuning advice related to my tune and AFR. I have a Nitrious Outlet plate kit along with a Nitrous outlet dedicated fuel system set to 58 psi on an LS1 with a mild cam, ported 243 heads and LS6 intake. The car is tuned well NA and runs a 12.6-12.7 AFR consistently. When on the bottle I have 150 hp jets in it 62N 31F and ramp in on a progressive controller along with pulling a min of 6 degrees timing through BR7es plugs. With that jetting I am technically 2 jet sizes fat on fuel if i was running 55 psi of pressure. I also increased the PE commanded on my tune to 11.7 to add more fuel for safety. Last year the car ran 127 MPH without adding the extra fuel to the PE table, but AFR was around 12.5-12.7. After a few people gave me the look like i was going to burn down my engine I added more fuel and got it down to a low 12 AFR but lost 5 mph.
I've done some reading and have seen a number of people comment that AFR and Nitrous can be misleading. My question is should I be worried about 12.7 AFR on bottle? Im running more fuel than recommended via the jet chart, and bottle pressure is consistent at about 950 psi. Im by no means a professional racer so I cant say I've really read plugs at the end of the track after a pass, but from looking at them after a night of racing I dont see any evidence of detonation or excessive heat.
What advice is out there, should I try to add more fuel and get AFR down, or is AFR not the right tool to use for this situation?
Thanks for the help
I've done some reading and have seen a number of people comment that AFR and Nitrous can be misleading. My question is should I be worried about 12.7 AFR on bottle? Im running more fuel than recommended via the jet chart, and bottle pressure is consistent at about 950 psi. Im by no means a professional racer so I cant say I've really read plugs at the end of the track after a pass, but from looking at them after a night of racing I dont see any evidence of detonation or excessive heat.
What advice is out there, should I try to add more fuel and get AFR down, or is AFR not the right tool to use for this situation?
Thanks for the help
I would read the plugs and give the engine what it wants. I don't see a low 12 afr losing 5 mph compared to mid 12. You would literally have to be flooding the engine with fuel like 10's AFR to lose that kind of power. I would suspect you have a issue with your wideband.
10 Second Club
Joined: Aug 2010
Posts: 4,467
Likes: 193
From: Harford Co. Maryland
Maybe it's my meter or the gauge ? I got my best NA runs on 12.0 AFR... upper 12's were .3-.5 slower.
So, agree with the above.... dial in for best mph NA and dial the N₂O in there.
So, agree with the above.... dial in for best mph NA and dial the N₂O in there.
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TECH Apprentice
Joined: Oct 2015
Posts: 310
Likes: 24
If it's to lean it will pop and snort and may not burn a piston.
if it's to rich and has to much timing it will burn a piston torch a head pop a ring land ect with no warning, but also will make the most power.
your choice. I choose to miss a little lean and light timing when working on a TUNEUP.
I run afrs .2 richer than it likes on motor to start a new tune. Lean it out the .2 and see if it picks up. After that start to add back timing.
Timing by far is the most dangerous thing to play with.
if it's to rich and has to much timing it will burn a piston torch a head pop a ring land ect with no warning, but also will make the most power.
your choice. I choose to miss a little lean and light timing when working on a TUNEUP.
I run afrs .2 richer than it likes on motor to start a new tune. Lean it out the .2 and see if it picks up. After that start to add back timing.
Timing by far is the most dangerous thing to play with.
If it's to lean it will pop and snort and may not burn a piston.
if it's to rich and has to much timing it will burn a piston torch a head pop a ring land ect with no warning, but also will make the most power.
your choice. I choose to miss a little lean and light timing when working on a TUNEUP.
I run afrs .2 richer than it likes on motor to start a new tune. Lean it out the .2 and see if it picks up. After that start to add back timing.
Timing by far is the most dangerous thing to play with.
if it's to rich and has to much timing it will burn a piston torch a head pop a ring land ect with no warning, but also will make the most power.
your choice. I choose to miss a little lean and light timing when working on a TUNEUP.
I run afrs .2 richer than it likes on motor to start a new tune. Lean it out the .2 and see if it picks up. After that start to add back timing.
Timing by far is the most dangerous thing to play with.
TECH Fanatic
Joined: Mar 2014
Posts: 1,266
Likes: 165
Tune for MPH. Start with the timing. When you see it makes no difference increasing the timing, back up one. Definitely make sure your afr's are decently close before doing this, but don't touch the fuel while doing the timing. Then when that is done, start with the fuel. Again, tune for mph. Try your best to lay down the same passes to get the best readings. Once this is set on motor you start over on nitrous not touching the motor tune. Then pick out the amount of nitrous you want to spray and go by the charts at first for the fuel jet. You are tuning with the fuel for each particular size nitrous jet. Then tune up and down from there for MPH with the fuel jets. Use the 2 degrees per 50HP on the retard to be safe and watch your plugs for the timing mark to be in the right spot and it will translate into the best MPH. Once you have it there finish with the fuel. AFR gauges are good to get you close but MPH is what will finish your tune and still be safe. Watch the plugs closely. Once you got it right, you will notice the temp staying lower too.
I would suggest to anyone starting out to have their system flowed by a good nitrous dealer. They will give you several tunes to get you started and will be very close if not dead on. Nitrous Outlet is a vendor here and is definitely one of the best. The after the sale information they are very happy to share and help you with is priceless. Very knowledgeable and great people to deal with.
I would suggest to anyone starting out to have their system flowed by a good nitrous dealer. They will give you several tunes to get you started and will be very close if not dead on. Nitrous Outlet is a vendor here and is definitely one of the best. The after the sale information they are very happy to share and help you with is priceless. Very knowledgeable and great people to deal with.
