[PERFORMANCE] Something interesting that I noticed..
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From: Lakeland, FL
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St. Jude Donor '03, '06, '17
Originally Posted by Aflac
did you compare to anyone else that was running at the same time? if they did the same thing, that would tell me that the track changed.
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St. Jude Donor '03, '06, '17
Originally Posted by Glensgages
For the most-part, "fast-times" (low-ET ) is a function of traction, clutch, and gearing, and how the available HP is being applied, while "speed" (MPH ) is a function of HP being made:
I don't follow the NHRA circuit like I used to (back-then, Heartland Park Topeka hosted their National event in late-September/early-October, so the air would've been much-better than mid-summer ), but I'm assuming you are talking about low-ET at HPT, which would be a function of traction, clutch, and gearing, and how efficiently the available HP is being used.
Topeka has ALWAYS been one of the best-prepped tracks on the tour, which may explain the low-ETs that we see in bad-air.
The Tony Schumacher-driven, Alan Johnson-tuned U.S. ARMY Top Fueler went 336 +tax at Columbus, and 337 & change at Brainerd, earlier this year, 2 tracks never known for low-ET:
they ran the big-speed due to nearly-optimal atmospheric conditions.
Ollie:
you said earlier that you slowed-up .07-seconds in 1320', slowed-up .02-seconds in 60', and lost 2 MPH when the air got slightly-better.....
#1- I think the fact you LOST 2 MPH in better air says it wasn't making as-much smoke at 2300' DA is it did at 2700' DA.
#2- 'typically', for each .01-second you gain/lose in 60', your 1320' ET is effected approx 1.5-to-2 times as-much, when all other factors (DA' and available HP ) remain the same, and the trap-speed would remain constant.
(i.e.- a 60' that is .02-slower would typically mean the 1320' ET would be .03 or .04-seconds slower, but you slowed-up .07 seconds)
In the evening run, you were slower to 60', but even-SLOWER the further you went, when compared to the earlier 11.14 run.
I've not seen the ET-slips, but I'd 'guesstimate' the 11.21-run, when compared to the 11.14-run, was:
+.02x to 60', which you already stated
+.035 to 330'
+.05x to 660'
+.06x to 990'/1000'
+.07x to 1320'
..... am I even-CLOSE?????
I don't follow the NHRA circuit like I used to (back-then, Heartland Park Topeka hosted their National event in late-September/early-October, so the air would've been much-better than mid-summer ), but I'm assuming you are talking about low-ET at HPT, which would be a function of traction, clutch, and gearing, and how efficiently the available HP is being used.
Topeka has ALWAYS been one of the best-prepped tracks on the tour, which may explain the low-ETs that we see in bad-air.
The Tony Schumacher-driven, Alan Johnson-tuned U.S. ARMY Top Fueler went 336 +tax at Columbus, and 337 & change at Brainerd, earlier this year, 2 tracks never known for low-ET:
they ran the big-speed due to nearly-optimal atmospheric conditions.
Ollie:
you said earlier that you slowed-up .07-seconds in 1320', slowed-up .02-seconds in 60', and lost 2 MPH when the air got slightly-better.....
#1- I think the fact you LOST 2 MPH in better air says it wasn't making as-much smoke at 2300' DA is it did at 2700' DA.
#2- 'typically', for each .01-second you gain/lose in 60', your 1320' ET is effected approx 1.5-to-2 times as-much, when all other factors (DA' and available HP ) remain the same, and the trap-speed would remain constant.
(i.e.- a 60' that is .02-slower would typically mean the 1320' ET would be .03 or .04-seconds slower, but you slowed-up .07 seconds)
In the evening run, you were slower to 60', but even-SLOWER the further you went, when compared to the earlier 11.14 run.
I've not seen the ET-slips, but I'd 'guesstimate' the 11.21-run, when compared to the 11.14-run, was:
+.02x to 60', which you already stated
+.035 to 330'
+.05x to 660'
+.06x to 990'/1000'
+.07x to 1320'
..... am I even-CLOSE?????
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From: Lakeland, FL
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St. Jude Donor '03, '06, '17
Originally Posted by 427Hotrod
With all the other variables...like engine, trans and rear temps etc taken care of..
I'm inclined to think of the mixture/timing etc and not making power. If you lose 2 mph, you aren't making as much power.
So my thoughts are that your tune is pretty close in the low humidity/hot weather.
Humidity is moisture and moisture displaces space that could be taken up with oxygen. So even though temps are down, you aren't getting as much oxygen in the cylinders as you might think. So if tune was good in the heat..or even a little fat, when humidity goes up, you may be even more fat.
I know the A/F ratio is a neat tuning tool...but it's just that. it is NOT a final determiner of correct jetting. Only plugs will tell you that on a motor doing what you're doing.
I know you are just starting to play with jetting on it,,,but you need to get a high intensity light and magnifier so you can really see deep into plugs and get someone to spend a little time with you showing you what is what. Reading plugs is as much art as science. Listen to whoever you find that knows there stuff.
What have you noticed on baro pressures?
JIM
I'm inclined to think of the mixture/timing etc and not making power. If you lose 2 mph, you aren't making as much power.
So my thoughts are that your tune is pretty close in the low humidity/hot weather.
Humidity is moisture and moisture displaces space that could be taken up with oxygen. So even though temps are down, you aren't getting as much oxygen in the cylinders as you might think. So if tune was good in the heat..or even a little fat, when humidity goes up, you may be even more fat.
I know the A/F ratio is a neat tuning tool...but it's just that. it is NOT a final determiner of correct jetting. Only plugs will tell you that on a motor doing what you're doing.
I know you are just starting to play with jetting on it,,,but you need to get a high intensity light and magnifier so you can really see deep into plugs and get someone to spend a little time with you showing you what is what. Reading plugs is as much art as science. Listen to whoever you find that knows there stuff.
What have you noticed on baro pressures?
JIM
However, coolant temperature could have something to do with the slower ET.. but I'm not sure... The coolant temp was about 20 degrees hotter when I ran 1.5 mph slower..
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From: State of Confusion
Originally Posted by GrandSportC3
If the traction and the .02 slower 60' time would've been the reason, the mph would've still stayed the same.. There's no explanation for the lower mph.....
poor traction and the .02-slower short-time isn't the ONLY reason you went .07-seconds slower.
It appears your ignition or jetting isn't allowing you to capitalize on the better atmospheric conditions, and you made less power, as-evidenced by the lower trap-speed.
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From: Lakeland, FL
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St. Jude Donor '03, '06, '17
Originally Posted by Glensgages
That is what I'm trying to say :
poor traction and the .02-slower short-time isn't the ONLY reason you went .07-seconds slower.
It appears your ignition or jetting isn't allowing you to capitalize on the better atmospheric conditions, and you made less power, as-evidenced by the lower trap-speed.
poor traction and the .02-slower short-time isn't the ONLY reason you went .07-seconds slower.
It appears your ignition or jetting isn't allowing you to capitalize on the better atmospheric conditions, and you made less power, as-evidenced by the lower trap-speed.
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From: St Louis Missouri
I can agree with this post that there isn’t a simple answer for this. I would only like to bring up that along with the tunning that can be altered with the atmospheric conditions, the cooler denser air means that the engine has to push the vette through a cooler denser air. At 32 degrees air is about .081 lb/cubic ft, and at 100 it’s only .071 lb/cubic ft. It may not seem like a lot, but you have to push a lot of air.
