Lemonfresh

iTrader: (1)

I have searched and found a few threads about altitude and the FD. However I'm not really finding the answer I am looking for.

At higher altitudes any motor will run with less power. N/A motors lose about 3% of their horsepower per 1000 feet above sea level. Does this formula still carry over to inducted motors? I would think the turbos would make up for the lack of natural intake pressure, it would just make them work harder.

My FD is stock except for an Apexi intake and a RB dual exhaust. I live at 4200 ft above sea level. If altitude does sap some power out of inducted cars, what kind of power loss would I be looking at? Also, can a good tune eliminate the altitude factor?

Thanks for your thoughts guys.

RLaoFD

iTrader: (6)

maybe someone can verify this, but I've heard that the turbos just take longer to spool and the power band is more peaky, but there is not really a loss of MAX power for forced induced cars at different altitudes. Once the turbos get going (full boost), I think the car will be unchanged relative to driving at a lower altitude. Of course, I may be wrong.

Tom93R1

iTrader: (2)

The turbos will spin to a higher RPM to achieve the same boost levels. I have lived with my FD as a daily driver in Phoenix at only 1200 feet and in Colorado Springs at over 7000 feet. The boost pattern was off while in CO, I had to fix it with bleed valves then I would just say it always seemed a little more laggy up there compared to Phoenix. The only time I really noticed a big change in performance due to elevation is when driving up in the mountains over 10,000 feet. The boost pattern would really get screwed up and I would mostly lose lots of low end.

I think peak HP could be affected because of this, but not to the same extent as peak HP of an N/A engine. At 4200 feet you probably would not notice a bit of difference compared to sea level.

jeff p

higher altitude means less dense air. so the turbos will run hotter and work harder resulting in slower response. I would think water/ meth injection would help out in this area. experts please comment for more info.

Jeff

oo7arkman

iTrader: (2)

This is my experience as well. While living in steamboat colorado (7000 and my condo was at 8500 up in the pass) I noticed it took a little longer to spool and my temps seemed to run a bit hotter due to the increased speed of the turbines. The car felt a little slower, but then in that area there are really no safe (long stretches away from police) to open the car up.

I have always noticed that 1/4 mile times are always slower at the higher alt's both for na and fi cars. I am sure this has to do with lower overall power levels, but then agian it could be just b/c the turbos are taking longer to achieve desired boost levels. This would not necessarily mean overall less power, but peak power coming on much later in the rpms decreasing the overall amount of available power. That is really my best guess.

Being at the altitude you are at I do not really think you will see much of a difference. Especially in the area you live with all the moisture in the air it should help compensate for less dense air due to altitude.

kf3er

iTrader: (1)

I moved from Seattle to Denver this past June. My '94 was tuned for ~500ft above sea level. Very strong and perfect boost pattern. I have a dp, CB,intake, coolcharge II, '99 specs, Apexi fc, innovate WB and Hallmann MBC's. My pattern in Seattle was 12-10-12. MPG's ~ 16.5 combined. Instant spool. Fast.

Denver is a whole 'nother story. Ilive at 6500ft and my initial pattern was, well, it wasn't really a pattern at all. Transition was very late(~5200rpm) and depending on gear and rpm when I put the spurs to her there might not be any noticable transition at all. MPG's ~18.5 combined.

I've done a little sorting and I've now got a pattern of 15-10-15 on the boost guage which is absolute and close to the power of 12-10-12 at sea level (seat of pants). Transition is still at ~5200rpm and nothing I seem to do really has much effect. Off the line she's sloooowww to spool. I haven't gotten around to retuning as the weather has turned too cold.

I'm so disappointed in how the car responds to the altitude here in Denver that I'm seriously considering selling it. I've had it since new, 15 years this Feb. My oldest son turns 16 next year and I've always assumed that would be the end of my sports car days anyway.

Altitude is great if your in a plane, no so good in an FD.

finnicky7

Interesting, I run a single, and have not noticed any significant loss of power. I was at 800ft up until Sept/08. I still am running on my tune from MI too. I will be tunning it and dynoing in the spring, I guess that will tell me more about the effects of altitude.