86-87 Accessory Bracket Wanted

Tom Kelly

Active Member
Joined
Jun 23, 2016
Unlike more rabid racers, I only tune once a season. I was wondering if there is a guide for adjusting for temperature changes? For example, Saturday I will spend the day at Lebanon Valley Dragway finishing up my tune. The temperature will average low 80's if the weather gods are accurate and benevolent. So let's say in the fall I am racing and the temperature is low 60's. Absent re-tuning is there a general rule on adjusting fuel to accommodate change in temperature from when the car was dialed in? I know that in general we go leaner in warmer weather to accommodate the less dense air and the opposite in colder air but wondering if there is a handy guide as to how much per 10 degrees for example. Thanks
 
I bracket raced in temps from mid 40's to mid 90's with humidity in the mid 30's to mid 90's. Fueling requirements change minute to minute on temp/humidity change. Humidity trumps temperature. For example, my car would pick up 2.3 tenths on a 15 percent humidity drop. I used a cheapass thermometer/barometer to check the temp/humidity change from run to run. When I was called to the lane I'd compare the temp/humidity from the last run and adjust the high gear fuel to keep the car on its dial, or I'd change the dial on the window. Guys blow these cares up cuz they don't realize how temp/humidity affects fueling.
 
Tom, I can't give you a guide cuz every combo is gonna react differently to temp/humidity change. Record your ET/MPH and the temp humidity for each run. You'll soon figure out your fueling requirements for any temp/humidity.
 
As always, plenty of good input on this forum. Like many of us I have a turbotweak chip with a scanmaster 2.2 and a powerlogger as well as alky kit and wide band a/f sensor. I understand there are many variables and so generalities are hard to come by. HOWEVER, In my case, my current settings (going to Lebanon Saturday) based on several 0-70 mph runs on my local dragstrip (Rte 7) are: Parameter 1 = 131; Parameter 2 = 134. Parameters 3 and 4 = base 128. This has resulted in no KR at WOT and my a/f is generally in the low to mid 10's (varies a bit as it shifts). So based on your experiences, how high and how low have you had to set parameter 1 and 2 from base 128 to accommodate temperature and humidity. While we are kicking it around, when do you turn to timing to accomplish no KR as opposed to fuel?
Still learning. TK
 
When my buddy and I ran 5.7 chips we both needed to add fuel when the temps dropped to the 40s. If I remember right is was about 2 digits richer. Like mentioned above, each car will like it's own tune. You got plenty of info so all you need to do is monitor it as the temps drop. A quick tweek and your good.
 
I'd adjust high gear fuel to keep the car on its dial. If it got warmer after morning dial in runs, then I'd subtract high gear fuel. If it got cooler I'd add high gear fuel. I paid more attention to humidity than temp. Again, you need to record temp/humidity for each run so you know what to do in each situation.
 
I'd adjust high gear fuel to keep the car on its dial. If it got warmer after morning dial in runs, then I'd subtract high gear fuel. If it got cooler I'd add high gear fuel. I paid more attention to humidity than temp. Again, you need to record temp/humidity for each run so you know what to do in each situation.
Wondering how you would describe the effect of humidity on necessary fuel adjustments. Higher humidity = more or less fuel? Has anyone turned to timing changes or do most drivers leave timing at 128?
 
Leave the timing on Erics defaults. I added 6 degrees of low gear timing with his 112 race chip, but I don't recommend messing with timing unless you know what you're doing. Cool dry air, and these engines lean out in a hurry.
 
Leave the timing on Erics defaults. I added 6 degrees of low gear timing with his 112 race chip, but I don't recommend messing with timing unless you know what you're doing. Cool dry air, and these engines lean out in a hurry.
That's what I thought. What are your thoughts on humidity effect on lean/rich?
 
There are a lot of variables that affect AFR as stated.

During T&T around here, you are lucky to get 3 passes in a 5 hour period, so you have to maximize the efficiency. If the temperature changes, and the car doesn't have a closed loop system, I start with my rule of thumb. Still have to watch everything real close. The number isn't a number pulled out of the air but was the analytical result of hundreds of logs during a 12 year period.
 
There are a lot of variables that affect AFR as stated.

During T&T around here, you are lucky to get 3 passes in a 5 hour period, so you have to maximize the efficiency. If the temperature changes, and the car doesn't have a closed loop system, I start with my rule of thumb. Still have to watch everything real close. The number isn't a number pulled out of the air but was the analytical result of hundreds of logs during a 12 year period.
3 Passes in five hours is pretty standard here too. I am optimistic about tomorrow because there are no events planned so just T&T. Weather near perfect too. Sunny and low to mid 60's. Now that I have added wideband and data logger I feel more prepared to find the optimum performance on my GN than ever.
 
3 Passes in five hours is pretty standard here too. I am optimistic about tomorrow because there are no events planned so just T&T. Weather near perfect too. Sunny and low to mid 60's. Now that I have added wideband and data logger I feel more prepared to find the optimum performance on my GN than ever.
To maximize your ET you have to dial in the low gear fueling with Erics 5.7 chip...that's why low gear fueling is adjustable with it. Most only look at the AF at the traps. If you're not adjusting low gear fueling, you're leaving a shit load on the table.
 
To maximize your ET you have to dial in the low gear fueling with Erics 5.7 chip...that's why low gear fueling is adjustable with it. Most only look at the AF at the traps. If you're not adjusting low gear fueling, you're leaving a shit load on the table.
Indeed. I have already differentiated between 1st gear and the top gears just in my 0-70 tuning on the highway. When I had narrowed the KR to only in first gear I added a bit more fuel there only and it worked like a charm. The powerlogger makes it easy,
 
Indeed. I have already differentiated between 1st gear and the top gears just in my 0-70 tuning on the highway. When I had narrowed the KR to only in first gear I added a bit more fuel there only and it worked like a charm. The powerlogger makes it easy,
Bring up the gauge panel on PL...use the arrows keys to advance frame by frame. You can see what your 02/AF fueling is at the 1-2 and 2-3 shift points to adjust your low gear fueling. KR on my engines came in around the 750's, so I'd adjust low/high gear fueling to the 770's to play it safe. I'd throw a shitload of low gear timing at it as well...but I only recommend doing it in small increments.
 
Bring up the gauge panel on PL...use the arrows keys to advance frame by frame. You can see what your 02/AF fueling is at the 1-2 and 2-3 shift points to adjust your low gear fueling. KR on my engines came in around the 750's, so I'd adjust low/high gear fueling to the 770's to play it safe. I'd throw a shitload of low gear timing at it as well...but I only recommend doing it in small increments.
Well tomorrow will be the first time I am able to do full 1/4 mile runs since adding my new instrumentaiton. But I am ready with a good 0-70 tune and so will save time tomorrow. I have only gone up to 20.5 psi boost so I intend to push that to 22-23 tomorrow. I will keep track of weather conditions and include that in my log. I don't get to the track often so easiest is to limit boost a bit to protect the engine. I understand heat soak in intercooler can be an issue too so a bit of time between runs helps there. My only real goal is to achieve 11's. Even 11.99 is okay. My previous experience is with my 66 GS which I finally got into the 13's at 100. This car is so much faster and so much more interesting.
 
Top