MY 85 GT
10 Year Member
Changing Things Up This Season...1st Track Outing!
- Thread starter RangerJoe
- Start date
I run my car 12.8-13 na wot. The 12.5 is an old rule of thumb. After spending time tuning my car and many others reading a lot of information from some of the best (Dennis Ramsey, Kenne Bell) anything below 12afr is there to cool the chamber and quench detonation. I picked up 40hp going from an 11.8 to a 12.2 afr.
After a session or a hard pass I always pull a plug from each bank and give them a check, remember a wideband pulls a reading from 4 cylinders. There could be as much as a .8 afr spread between the richest and leanest. Sometimes it's best to stay on the safe side.
However imo I would lean it out to around 12
My understanding is that you can get hurt by going lean, but it's a very small window. With fuel, you are unable to burn all of it and it starts building in areas like the ring lands and eventually things get just right to light it off....then lots of heat is generated and things break and melt. This is my understanding of it.
Timing can be added to help with a rich condition, but it's a bandaid from what I have gathered. Like @srtthis suggested, get the AFR right then add timing. This is the same concept as a really efficient cylinder head needing less timing to make peak power. If it efficiently burns all the fuel and oxygen, therr is no need to spark sooner and allow a longer burn time.
Car is loaded, new ngk plugs in with a 93/110 mix and a 100rwhp jet in the nozzle. Cross your fingers for Me!
Joe
Timing can be added to help with a rich condition, but it's a bandaid from what I have gathered. Like @srtthis suggested, get the AFR right then add timing. This is the same concept as a really efficient cylinder head needing less timing to make peak power. If it efficiently burns all the fuel and oxygen, therr is no need to spark sooner and allow a longer burn time.
Car is loaded, new ngk plugs in with a 93/110 mix and a 100rwhp jet in the nozzle. Cross your fingers for Me!
Joe
Gear grabber
Well-Known Member
- May 23, 2016
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Well, big thanks to Derek @srtthis for his help last night. I went to Atlanta Motor Speedway's Friday night drags, designed to mimic street racing, sorta. They did add a tree recently, but no timers. 1st across the stripe wins. I entered the Street Mod class, consisting of a single power adder and hard tires.
I jetted it with a 100 shot and left the timing at 10 with a 110/93 mix. Progressive was set up with a .5 second delay, starting at 30% - 100% in 1 second. 1st run felt good and I killed the motor at the end and pulled off. Sent the pics of the plugs to Derek and he provided me with some great advice. Ended up adding a few degrees back in and ran it this way the rest of the night.
Our class was very slim due to threatening weather, but I ended up winning the class with the grand prize being a trophy, lol.
Here are a few pics and videos.
View: https://youtu.be/wtwwyc6rd-g
I jetted it with a 100 shot and left the timing at 10 with a 110/93 mix. Progressive was set up with a .5 second delay, starting at 30% - 100% in 1 second. 1st run felt good and I killed the motor at the end and pulled off. Sent the pics of the plugs to Derek and he provided me with some great advice. Ended up adding a few degrees back in and ran it this way the rest of the night.
Our class was very slim due to threatening weather, but I ended up winning the class with the grand prize being a trophy, lol.
Here are a few pics and videos.
View: https://youtu.be/wtwwyc6rd-g
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Gear grabber
Well-Known Member
- May 23, 2016
- 283
- 152
- 63
MY 85 GT
10 Year Member
MY 85 GT
10 Year Member
Thanks yes i have a wideband and i data log i keep an eye on things each pass...i did notice my Motor tune is on the rich side [lows 12s even dips into the high 11s] that explains a few things i will recheck my Nitrous tune and see what that is again...thanks
No idea, they Don't have timers at this track/event. They started this event many years ago in an attempt to stop street racing. It was arm drop, 1st to the finish win. Then a few years back they added a tree. The only time I have ran it on a timer with hard tires, it went 7.9x 1/8th mile. Hoping it will go 7.4x, maybe lower. We will see.
Joe
I ended up at 12, but looking at the strap I think it could take more. I wanted to ask if you think the heat range 7 is still too cold? I kind of think it may be.
Honestly, I am really surprised the Street tires took it. My buddy took some cell phone vids and got a pretty good one track side. I will try to get them posted up.
For anyone who might be curious, I used 4 lbs of nitrous. That consisted of a 50 shot run in Mexico, three 100 shot runs at the track, purges for all 4 runs, and a few leak tests. My guess is at this level, a 10 lb bottle would bet 5 to 6 good runs before pressures get too low.
Joe
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