Fun time at the track
09-29-2009, 07:47 AM
#22
6th Gear Member
Join Date: Sep 2006
Location: NC
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Nice one.. your times are looking great for how bad the DA was... are you going to make the MFBA rental at Cordova? It's a drive but it's from 9am to 5pm and you're guaranteed to run until you break. I won't even mention the DA should be at least 500ft or less. 
09-29-2009, 10:50 AM
#23
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I've been told my times are impressive for not slipping the clutch hardcore and power shifting. However, my one friend said he would be surprised if I were to hit a mid 11 even in perfect weather on Slicks. I LOL'd.
I'll let ya know about Cordorva though.
09-29-2009, 10:51 AM
#24
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09-29-2009, 10:55 AM
#25
Mish-ogynist
Join Date: Nov 2007
Location: Helena, MT
Posts: 3,780
stock termis will run a low 13 at 3200ft DA.. maybe another mph or 2 more on the trap.. too bad there weren't any stock ones there for you to compare to. congrats on making it out to the track it's a blast.. are you hooked now?
maybe you'll get a better idea of how your cars run against other cars now at the track/from a dig.. since roll racing isn't really racing anyway
maybe you'll get a better idea of how your cars run against other cars now at the track/from a dig.. since roll racing isn't really racing anyway
09-29-2009, 10:59 AM
#26
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stock termis will run a low 13 at 3200ft DA.. maybe another mph or 2 more on the trap.. too bad there weren't any stock ones there for you to compare to. congrats on making it out to the track it's a blast.. are you hooked now?
maybe you'll get a better idea of how your cars run against other cars now at the track/from a dig.. since roll racing isn't really racing anyway
maybe you'll get a better idea of how your cars run against other cars now at the track/from a dig.. since roll racing isn't really racing anyway
My G/F is the one that popped her cherry at the track, not me.
Ironically enough, in similar DA, with bad pressure and 50 degrees, I broke 12's Stock, and trapped a best of 113, LOL. Bad drivers running 13's with under a 108-109 trap? Who knows.
09-29-2009, 04:23 PM
#27
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Here is a link to where the videos are posted.
The car I raced was a 10.73 or 10.93 Mustang. For some reason, up top, I stayed semi close to him, as others have mentioned to me. I didn't notice it until I saw this video, and compared my actual run against him.
http://www.windycitystangs.com/forum...read.php?t=978
The car I raced was a 10.73 or 10.93 Mustang. For some reason, up top, I stayed semi close to him, as others have mentioned to me. I didn't notice it until I saw this video, and compared my actual run against him.
http://www.windycitystangs.com/forum...read.php?t=978
09-29-2009, 05:11 PM
#28
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Join Date: Oct 2003
Location: North Cackilacky
Posts: 8,635
My Cobra has been to the track before, and I have been to the track a few times prior.
My G/F is the one that popped her cherry at the track, not me.
Ironically enough, in similar DA, with bad pressure and 50 degrees, I broke 12's Stock, and trapped a best of 113, LOL. Bad drivers running 13's with under a 108-109 trap? Who knows.
My G/F is the one that popped her cherry at the track, not me.
Ironically enough, in similar DA, with bad pressure and 50 degrees, I broke 12's Stock, and trapped a best of 113, LOL. Bad drivers running 13's with under a 108-109 trap? Who knows.
When my old car was going mid 7's I calculated the DA for my own amusement and it was over 3400'. That was with 367rwhp. That would equate to a mid'ish 11 second 1/4 pass. So by Mishri's calculations, my 367rwhp, stock weight, stock suspended, DR'ed, LS1 would have ran near 11 flats.....I just don't see that happening.
09-29-2009, 05:48 PM
#29
Mish-ogynist
Join Date: Nov 2007
Location: Helena, MT
Posts: 3,780
are you sure you entered teh calculations in properly to get the correct DA?
do you still have the date/time/location of the track? i'd like to verify.
and converting the 1/8th to a 1/4.. i've seen some weird things going on with that, and isn't something I would be able to pinpoint a time on.
The best thing to use the correction factors for is to determine how well your car is running from one day to the next and for me that seems to have been pretty accurate.. w/o determining that i'd be able to say i picked up 1.1 in the 1/4 with gears/pulleys/plates when in reality it was more like .5.. and I lost time when i switched to DRs.. for every .1 on the 60ft it equated to an extra .1 on the ET.. but if i didn't correct that i would be thinking I lost .5 not .2 or .3
and as i've said before, once you take boost and n20 into the equation it throws a lot of.. and depending on how you are using your n20 and how big of a shot, you might not get any correction at all.. and with enough boost you dont get any correction either, but it depends on the current conditions wether you do or not..
I have less compression up here at this altitude.. must be horrible for people at 7,000ft or higher.. I can run a 93 octane tune on 91 octane gas down here though so I can advance my timing to make up for that.. and if I did do that then i think i'd get less correction, people with custom dyno tunes I think wont suffer as badly at higher elevations in good wether compared to people with canned tunes or stock running at high elevations.
here is some good copy pasta for you guys incase you forgot it:
Really think a lot about the theory behind NA and FI, it is nice to have a good understanding of it.
The true correction for FI depends on how much boost you are making. The 1/2 correction factor is accurate if you are making 14.7psi of boost, below that and you should get more correction and above you get less.
I'll use a NA car, one making 14.7psi boost and my Buick as an example making 21psi of boost.
Say that we have a day with a DA of 6000' (pretty common on a summer day in Acton). That equates to 11.78psi of air pressure. Percent loss is going to be absolute pressure up here divided by absolute pressure at sealevel
14.7psi / 14.7psi = 1 (sealevel has no power loss so no correction)
11.78psi / 14.7psi = 80.1% NA (19.9% less power for the NA car))
(11.78psi + 14.7psi) / (14.7psi + 14.7psi) = 90.07% (9.93% less power or 50% correction for 14.7psi boost)
(11.78psi + 21psi) / (14.7psi + 21psi) = 91.82% (8.18% less power or 41% correction for 21psi)
What about a 40psi dsm...
(11.78psi + 40psi) / (14.7psi + 40psi) = 94.66% (5.34% less power or 27% correction for 40psi)
How about a low boost supercharger, my GTO had 5.5psi
(11.78psi + 5.5psi) / (14.7psi + 5.5psi) = 85.55% (14.45% less power or 73% correction for 5.5psi)
I gotta go eat, but you should get my point. If you are running very high boost then taking 1/2 of the NHRA correction factor is overly optimistic. Vice Versa, if you are runnning way low boost (i.e. GTO) and you take 1/2 of the NHRA correction factor then you aren't correcting enough.
at higher elevations you are putting out less boost and lower compression than at sea level.. the DA correction basically figures out what the change is and like Grabber said, low atmospheric pressure even with low temps still can give you crap DA because you aren't getting the same compression or boost levels you would under higher atmospheric pressure..
alot of you guys are running boost or n20 if you really wanted to figure your times you would need to do a lot more calculation to get it within a .1 or so of what it would run in good conditions.. and the real test will be when you get lcose to 0 DA and see what you ran and if you think it was as good of a run as your high DA time and they are matching or within .1 you know you figured it properly. I can understand why a lotof you guys dont bother, especially if its just within a .2-.3 margin.. but when you are talking .5-1.0 sec.. you can't compare times like that.
do you still have the date/time/location of the track? i'd like to verify.
and converting the 1/8th to a 1/4.. i've seen some weird things going on with that, and isn't something I would be able to pinpoint a time on.
The best thing to use the correction factors for is to determine how well your car is running from one day to the next and for me that seems to have been pretty accurate.. w/o determining that i'd be able to say i picked up 1.1 in the 1/4 with gears/pulleys/plates when in reality it was more like .5.. and I lost time when i switched to DRs.. for every .1 on the 60ft it equated to an extra .1 on the ET.. but if i didn't correct that i would be thinking I lost .5 not .2 or .3
and as i've said before, once you take boost and n20 into the equation it throws a lot of.. and depending on how you are using your n20 and how big of a shot, you might not get any correction at all.. and with enough boost you dont get any correction either, but it depends on the current conditions wether you do or not..
I have less compression up here at this altitude.. must be horrible for people at 7,000ft or higher.. I can run a 93 octane tune on 91 octane gas down here though so I can advance my timing to make up for that.. and if I did do that then i think i'd get less correction, people with custom dyno tunes I think wont suffer as badly at higher elevations in good wether compared to people with canned tunes or stock running at high elevations.
here is some good copy pasta for you guys incase you forgot it:
Really think a lot about the theory behind NA and FI, it is nice to have a good understanding of it.
The true correction for FI depends on how much boost you are making. The 1/2 correction factor is accurate if you are making 14.7psi of boost, below that and you should get more correction and above you get less.
I'll use a NA car, one making 14.7psi boost and my Buick as an example making 21psi of boost.
Say that we have a day with a DA of 6000' (pretty common on a summer day in Acton). That equates to 11.78psi of air pressure. Percent loss is going to be absolute pressure up here divided by absolute pressure at sealevel
14.7psi / 14.7psi = 1 (sealevel has no power loss so no correction)
11.78psi / 14.7psi = 80.1% NA (19.9% less power for the NA car))
(11.78psi + 14.7psi) / (14.7psi + 14.7psi) = 90.07% (9.93% less power or 50% correction for 14.7psi boost)
(11.78psi + 21psi) / (14.7psi + 21psi) = 91.82% (8.18% less power or 41% correction for 21psi)
What about a 40psi dsm...
(11.78psi + 40psi) / (14.7psi + 40psi) = 94.66% (5.34% less power or 27% correction for 40psi)
How about a low boost supercharger, my GTO had 5.5psi
(11.78psi + 5.5psi) / (14.7psi + 5.5psi) = 85.55% (14.45% less power or 73% correction for 5.5psi)
I gotta go eat, but you should get my point. If you are running very high boost then taking 1/2 of the NHRA correction factor is overly optimistic. Vice Versa, if you are runnning way low boost (i.e. GTO) and you take 1/2 of the NHRA correction factor then you aren't correcting enough.
at higher elevations you are putting out less boost and lower compression than at sea level.. the DA correction basically figures out what the change is and like Grabber said, low atmospheric pressure even with low temps still can give you crap DA because you aren't getting the same compression or boost levels you would under higher atmospheric pressure..
alot of you guys are running boost or n20 if you really wanted to figure your times you would need to do a lot more calculation to get it within a .1 or so of what it would run in good conditions.. and the real test will be when you get lcose to 0 DA and see what you ran and if you think it was as good of a run as your high DA time and they are matching or within .1 you know you figured it properly. I can understand why a lotof you guys dont bother, especially if its just within a .2-.3 margin.. but when you are talking .5-1.0 sec.. you can't compare times like that.
Last edited by Mishri; 09-29-2009 at 06:04 PM.
