BlackICE
GT Owner
Outstanding runs Fastcat! :thumbsup
I guess my FGT is much like me, we don't like to run fast in the heat!
I guess my FGT is much like me, we don't like to run fast in the heat!
Texas Mile Results
- Thread starter AZGT
- Start date
STORMCAT
GT
Thanks Clinton. Is the TC dialed in ? Are you going to run at the Mov. Mile?
I wish it was closer to me..:biggrin
BigsGT
Tungsten GT Owner
Great Runs Brian! How did you get such clean slips? Mine are barely legible and my best had to be written over by the officials as it was so hard to read. Plus they were torn goofy; I'm ashamed to post them! :biggrin
STORMCAT
GT
Thanks Mr Big !! I guess the machine was freshly inked up and they tore them off with respect....:biggrin
tmcphail
GT Owner/Vendor
PL510*Jeff
Well-known member
BlackICE
GT Owner
I plan to do Mojave and better my speed. With the expectation of more favorable conditions, I hope to pass your TX mile speed, but doubt I would beat your speed in FL "mile." TC doesn't help much for the mile, since getting off the line quickly doesn't much that much of a difference in the terminal speeds. TC was great for a rookie like me on drag strip though. I allow me to launch without fear of the the very close concrete walls. It would be interesting to see what the TC system would do for a TT car where wheel spin is ever present in the 1-2 and 2-3 shifts. I remember Tony's wild video in Piko's car.
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Not so fast.
Ice,
The altitude at the Texas Mile is 324 feet above sea level. The altitude at the Mojave Mile is 2781 feet above sea level. I doubt any of us will improve the standing mile times we posted at the Texas Mile when we go out to Mohave. As a pilot I can tell you that the 2500 foot difference between those two runways equates to a 7% decrease in air pressure. The ambient pressure on a standard temperature and humidity day at Golidad, Texas is 14.3 pounds per square inch. The ambient pressure on a standard temperature and humidity day at the Mohave Airport is 13.3 pounds per square inch. The 7% decrease in air pressure equates to a 7% decrease in engine output. Our day at the Texas Mile featured high humidity and high temperatures, both of which decrease air density. In addition, in Texas we had a fairly stout crosswind which hindered speeds somewhat. All of that combined however will not add up to the 7% loss in air pressure we will experience at the Mohave Mile even if we get lucky and catch a cold, zero wind day.
I don't want to rain on anybody's parade but I think expectations regarding top speeds in Mojave should be realistic. If you really want to set some monstrous speeds, go to Borrego Springs or the Death Valley basin in midwinter. Both of those sites are below sea level and on a cold winter, no wind day, top speeds would be remarkable! I used to fly an aerobatic contest in Borrego Springs every winter and the cold, thick air there made my Pitts Special aircraft perform like an absolute monster!!
I'll see you in Mohave.
Chip
Ice,
The altitude at the Texas Mile is 324 feet above sea level. The altitude at the Mojave Mile is 2781 feet above sea level. I doubt any of us will improve the standing mile times we posted at the Texas Mile when we go out to Mohave. As a pilot I can tell you that the 2500 foot difference between those two runways equates to a 7% decrease in air pressure. The ambient pressure on a standard temperature and humidity day at Golidad, Texas is 14.3 pounds per square inch. The ambient pressure on a standard temperature and humidity day at the Mohave Airport is 13.3 pounds per square inch. The 7% decrease in air pressure equates to a 7% decrease in engine output. Our day at the Texas Mile featured high humidity and high temperatures, both of which decrease air density. In addition, in Texas we had a fairly stout crosswind which hindered speeds somewhat. All of that combined however will not add up to the 7% loss in air pressure we will experience at the Mohave Mile even if we get lucky and catch a cold, zero wind day.
I don't want to rain on anybody's parade but I think expectations regarding top speeds in Mojave should be realistic. If you really want to set some monstrous speeds, go to Borrego Springs or the Death Valley basin in midwinter. Both of those sites are below sea level and on a cold winter, no wind day, top speeds would be remarkable! I used to fly an aerobatic contest in Borrego Springs every winter and the cold, thick air there made my Pitts Special aircraft perform like an absolute monster!!
I'll see you in Mohave.
Chip
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BlackICE
GT Owner
Chip your points are all valid, with the possible exception to the differential in air density during our TX runs and what I expect in Mojave.
See http://en.wikipedia.org/wiki/Density_altitude
At TX the temperatures on the runway were between 100-110F (measured on my Homelink mirror
My guess is the humidity was over 70%. I expect Mojave temps to be 50-70 with a very humidity lower than 40%. If my numbers are right the air densities should be about the same, but I get to run more timing.
On the plus side of Mojave the much colder intake temperatures I will feel more comfortable in moving the ignition timing up a little. I was only getting 10 degrees of timing in TX due to the IAT2 of more than 170F at the end of the run. Note on dyno runs I was at 17.5 to 18 degrees of timing with IAT2 of less than 120F. Our intercoolers are just not very effective with 110F air blowing over them!
IMO the lost of timing killed more power than the low air density will at Mojave. I could always pop the 21 psi pulley on to somewhat compensate for the altitude.
See http://en.wikipedia.org/wiki/Density_altitude
At TX the temperatures on the runway were between 100-110F (measured on my Homelink mirror
My guess is the humidity was over 70%. I expect Mojave temps to be 50-70 with a very humidity lower than 40%. If my numbers are right the air densities should be about the same, but I get to run more timing. On the plus side of Mojave the much colder intake temperatures I will feel more comfortable in moving the ignition timing up a little. I was only getting 10 degrees of timing in TX due to the IAT2 of more than 170F at the end of the run. Note on dyno runs I was at 17.5 to 18 degrees of timing with IAT2 of less than 120F. Our intercoolers are just not very effective with 110F air blowing over them!
IMO the lost of timing killed more power than the low air density will at Mojave. I could always pop the 21 psi pulley on to somewhat compensate for the altitude.
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fjpikul
GT Owner
Hey, why don't you guys send this info to IndyGT and have him publish it in the "Journal of Irreproducible Results?"
J o i r
:lol :lol :lol :lol :lol
Post of the day Frank! You made me laugh out loud.
Chip
:lol :lol :lol :lol :lol
Post of the day Frank! You made me laugh out loud.
Chip
GTMikey
GT Owner
If I run 100 Octane which I can buy at the pump 2 miles from my house for $7 a gallon and I have a pulley and tune at Mojave, what do you think the speed range would be?
What risks or damage if any am I running using 100 Octane?
BlackICE
GT Owner
Torrie would know better, but my guess is with an optimized tune you might pick up somewhere between 30 to 50 HP.
Most of the HP in a top speed run is used to overcome wind resistance, so you have less HP but less air to push through too. So the thin air doesn't hurt as much as it would 1st seem to. The thinner air makes much more of a difference on a short run, lets say the 1/4, than a long run like the mile. On a infinitely long runway, If the HP output was constant (it is not) then the differences in terminal velocity between a run a sea level and one at 2600' will be very small.
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GTMikey
GT Owner
This is going to be my first of hopefully many mile events.
I had my 68 Shelby tuned for 100 Octane since they sell it by my house. When you say "Optimized" tune for the GT, can you be more specific? I can't do it myself but I have two guys here in SD who could do it for me.
Mike
I had my 68 Shelby tuned for 100 Octane since they sell it by my house. When you say "Optimized" tune for the GT, can you be more specific? I can't do it myself but I have two guys here in SD who could do it for me.
Mike
BlackICE
GT Owner
Fuels have a different stoichiometric ratio and density, so the open loop a/f ratio will probably need adjustment in the tune. Assuming that your MAF table was already on the button. you can just change the stoichiometric ratio value in the tune. Otherwise you have to play with the fuel and MAF tables. Also because of the higher octane you can and should advance the ignition timing to get the most out of the gas. I don't have a lot of 1st hand experience in this area and it is best, for the sake of you engine, to use someone that does! How many degrees? Too much and kiss your pistons goodbye!
GTMikey
GT Owner
I guess I could run a mixture of 93 and 100 and get a little boost without having to do any tuning mods. May get me 5MPH.
BlackICE
GT Owner
Unless your current tune is off, you will not pickup any power with a mix of race gas. Race gas only helps if you are willing to increase the boost and or timing. Some cars with knock sensors can benefit from a mix, but the FGT doesn't have knock sensors.
GTMikey
GT Owner
Yep, we increased the timing on my 428 Cobra Jet when I ran 100 Octane. Noticeable difference. That car is 100% stock off the showroom floor restored rebuilt CJ at. 30 over. I am going to have the same shop here bump the timing for me for the event.
tmcphail
GT Owner/Vendor
Clinton is correct. Increasing the octane alone with all other factors being relative will net 0 gain. If you have a calibration setup correctly for the specific fuel you want to run with the proper amount of advance that's where your HP/TQ gains will derive from.