this weekend is the first time at the track in my Z. these things are hard as hell to launch. i bogged at 2000, 3000 and 3500 rpm. finally tried 4000 and blew the tires. best et was 13.3x, best mph was 110. i know these times are low but consider this,
alt-6978ft
21%hum
25.3 hg
79f
also my 60fts were 2.2 and 2.3
ive been racing for alot of years but these animals are a different breed.
so any pointers?
Originally posted by bluZ06 alt-6978ft
also my 60fts were 2.2 and 2.3
Wait a minute - you raced it at almost 7,000 feet?!?
Your times are just fine at that altitude! There's a formula for how much HP you lose with altitude, but I can't remember it. But you've gotta be down about 25% in power at that height. Come down to sea level and watch what the beast will do then!
Your 60fts are also part of the problem, but they're not horrible. If you can get them past the 2.0 barrier, then you're good to go.
If you don't want to go to a sea level race track, you could always go with a twin turbo setup
__________________ '02 Z06 , Electron Blue, Vortex intake, Magnaflow X-pipe, Corsa Indy, Stainless Works LT headers, LS1 Edit, TB bypass, Hurst, MGW Gripper, Born 2/20/02 380 rwhp / 363 rwtq
no, i didnt have the tcs on but that is what it seemed like,,,it looked like it from the outside also,,had my friends ask me that same question,,lol.
yeah with the heat and high alt it really sucked. does anyone know what that would calculate to at sea level. also does a turbo car benefit from lower alt?
Originally posted by bluZ06 yeah with the heat and high alt it really sucked. does anyone know what that would calculate to at sea level. also does a turbo car benefit from lower alt?
Considering the roughly 25% power drop, I would estimate it would equal about the mid 12's at sea level.
Turbocharged cars have no benefit at lower altitudes, but have huge benefits at higher altitudes relative to naturally aspirated engines. Turbocharged cars perform the same at sea level as they do at 7,000+ ft. The forced induction automatically compensates for the less dense air at higher altitudes. Naturally aspirated engines can't do that.
blu, I had a buddy in N.M. Nice vue from the mountan on los alamos. 8k+ ft. The only way to get big power up in the clouds is more oxygen. So super charger, turbo's or NOS are a big help. Remember compresors(turbo,superchargers) only pack more cubic ft of air in. If you start with less densey of air, there's less oxegen in each cubic ft. But boost is a good way to go. Nitrous oxide is the inexpencive way to level the field with your sea level brothers. Ric
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02 EB/ModRed,VaraRam,160ts,fan switch,tbb,ripper,drag radials. Best ET 11.659,Best MPH 118.99,Best 60' 1.645
Originally posted by bluZ06 also does a turbo car benefit from lower alt?
A properly setup turbo car should [and generally will] perform the same at sea level and at high altitudes. This is because if you have set the boost level at say 10psi, the turbo system (which btw also includes the wastegate and boost controller) will pressurize the intake charge to 10psi; and 10psi at sea level is the same as 10psi at 8000 ft. Infact from my experience 10psi at 8000ft is better than 10psi at sea level because at 8000ft the ambient temperature is much lower and therefore a given volume of air at the same pressure will pack more oxygen molecules.
Well, everything is not so rosy though. If you have a turbo car you will need to take the following into account.
1) To pressurize less dense air, which is present at higher altitudes, the turbo has to work harder. I.e. it has to spin faster. If your turbo is not correctly sized (in other words if its too small), it will be over spun which can result in two kinds of problems: (a) premature wear of the turbo bearings and (b) over heating of the charged air.
2) The time the turbo will require to compress the intake air to a fixed pressure (say 10 psi) will be longer at higher altitudes because the ambient air pressure is lower. What this means is that turbo-lag (the biggest enemy of turbo cars) will be more pronounced.
What was your engine temp? I ran last week and couldn't get better then 220 degrees by the time I got to the staging area.
Bristol's track has elevation but I don't bog at all. I first tried to come out at an idle and floored it with 2.000 60' times. All my runs were 13 flat with exception when I tried to come out at or about 2000 rpm. Smoke city.
I used the comp mode each time. With no real cool down and a high engine temp that will rob you plenty. I had old fuel also (7 months old)with 700 miles on the car I'm confident once I figure out the best rpm to launch at I'm in the 12's. Of course again my engine temp will have to be lower.
High elevations will make your car feel like it's running retarted somewhat. I used to live in Calif. years ago and when we went to Tahoe or Reno the cars suddenly became sleds with the elevation.
Ran rich and retarted. As we came back to the Sacto valley the HP came back.
I went through 4 gears at 109 mph all the time but noticed in 3rd getting 6500 rpm the winding was slower and much slower in 4th which was about 5300 through the lights.
Practice in comp mode and remember the elevation makes you feel retarted and the only cheap solution is sea level.
Originally posted by Anil Rao
A properly setup turbo car should [and generally will] perform the same at sea level and at high altitudes. This is because if you have set the boost level at say 10psi, the turbo system (which btw also includes the wastegate and boost controller) will pressurize the intake charge to 10psi; and 10psi at sea level is the same as 10psi at 8000 ft. Infact from my experience 10psi at 8000ft is better than 10psi at sea level because at 8000ft the ambient temperature is much lower and therefore a given volume of air at the same pressure will pack more oxygen molecules.
Not actually correct in practice...
Nearly all wastgates use relative pressure differential, not absolute pressure, to control the dump. This is just because they are much simpler and easier to build. That means that the engine is a fixed amount over ambient pressure, not an absolute pressure. So a stock turbocharged engine will also make less power at altitude.
Now if you add an adjustable boost controller, you can up the wastgate pressure slightly to compensate
Nearly all wastgates use relative pressure differential, not absolute pressure, to control the dump. This is just because they are much simpler and easier to build. That means that the engine is a fixed amount over ambient pressure, not an absolute pressure. So a stock turbocharged engine will also make less power at altitude.
Now if you add an adjustable boost controller, you can up the wastgate pressure slightly to compensate
Exactly! That is why I didn't mention a stock car but a properly setup one.
Nearly all wastgates use relative pressure differential, not absolute pressure, to control the dump. This is just because they are much simpler and easier to build. That means that the engine is a fixed amount over ambient pressure, not an absolute pressure. So a stock turbocharged engine will also make less power at altitude.
Now if you add an adjustable boost controller, you can up the wastgate pressure slightly to compensate
Correct. I race Turbo charged cars for years and have turbo'ed almost everything I have owned (Have a turbo miata that runs mid 12's right now) and it does make a difference. Pressure and cfm's are a tough match. The same turbo at sea level will make more power because it the air is more dense coming into the compressor wheel. The compressor wheel flows the same amount of volume, but the volume is more dense. The more dense the air the more actual molecules or air are getting past the TB thus more power. You'll see much better times at sea level. I ran a 11.33 @ seal level and drove to CO and raced at a track and only pulled a 11.89. Some could have been my error, but I think my error is closer to a tenth of a second. Not sure about NA cars, but once I buy this ZO6 I'm sure i'll try and find out
Brian
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