Tuning for high altitude?
Thread Starter
Intermediate
Joined: Jan 2002
Posts: 37
Likes: 0
From: Seattle WA
Tuning for high altitude?
I'm looking to buy a '93 LT1 Vette from a guy in Denver, CO. He says it's tuned for high altitude and would need to be re-tuned (I live in Seattle, which is at sea level). Anyone know what this entails and whether or not I can do this myself or what I should expect to spend? Can you even tune for high altitude?Thanks, Anthony
Team Owner
Joined: Apr 2001
Posts: 22,267
Likes: 3
From: Dallas TX
Re: Tuning for high altitude? (rideklein)
I'm not certain, but my guess would be that you increase fuel ... in denver there is less air (oxygen), so less fuel is used to match the 12.4 ratio ... at sea level, there is more air so more fuel is needed to keep that 12.4 ratio.
Melting Slicks
Joined: Apr 2001
Posts: 2,105
Likes: 220
From: Ca.
Re: Tuning for high altitude? (rideklein)
You need to ask him what he means by "tuned". Some folk will just advance the base timing and decrease the fuel press. and call it tuned for alt. However if he had a custom chip burned then you'll need to change that-WOT fuel, timing and closed loop fuel. Any mods on it? If no mods and it is a custom chip, then you could just swap in a stock one and be good to go. And yes, you can tune for alt. Increasing the timing helps a lot! And decreasing the inj. pulse width while cranking helps with start up when hot and high-I've been trying to hit a good compromise with mine as I drive down the hill about once a week.
Drifting
Joined: Dec 2000
Posts: 1,851
Likes: 5
From: Liberal Kansas
Re: Tuning for high altitude? (rideklein)
I had the same question and here is the response I received.
MAP cars (SD and TBI) are automatically corrected for elevation by the MAP sensor. As you go up in elevation, the Kpas for a given load goes down. As long as you have GOOD VE table values, then the ECM will be able to correct properly (for mixture).
Pretty cool how these things work.
MAP cars (SD and TBI) are automatically corrected for elevation by the MAP sensor. As you go up in elevation, the Kpas for a given load goes down. As long as you have GOOD VE table values, then the ECM will be able to correct properly (for mixture).
Pretty cool how these things work.
Melting Slicks
Joined: Apr 2001
Posts: 2,105
Likes: 220
From: Ca.
Re: Tuning for high altitude? (Dan Plett)
Yes, I saw that info at thirdgen also. I'll have to check a friends SD up here to see how well it is compensating. However in looking at the tables for SD, I don't see how it could compensate for WOT; and then there's the timing.....
Drifting
Joined: Dec 2000
Posts: 1,851
Likes: 5
From: Liberal Kansas
Re: Tuning for high altitude? (drive it)
One of the components for which the PE mode/WOT is calculated is the fuel table. As BLMs change because of altitude, temp, humidity etc. the PE and WOT will change accordingly.
Safety Car
Joined: Mar 2000
Posts: 3,620
Likes: 2
From: Hillsboro OR
Re: Tuning for high altitude?
The fuel table values are Volumetric efficiency numbers and they are indexed by absolute barometric pressure. Those values stay the same unless the ability of the engine to draw air in has changed because of intake, heads, cam or exhuast mods. The computer should not need recalibrating for lower altitudes.
[Modified by AquaMetallic94LT1, 4:54 PM 1/21/2002]
[Modified by AquaMetallic94LT1, 4:54 PM 1/21/2002]
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Thread Starter
Intermediate
Joined: Jan 2002
Posts: 37
Likes: 0
From: Seattle WA
Re: Tuning for high altitude? (rideklein)
Well, I bought the car afterall. It's a 93 6spd with only 31k miles. Made for a nice roadtrip between Denver and Seattle. Thankfully, the winter weather was cooperative -- sunny skies and dry roads.
On the high altitude tuning -- seller thought it'd been "re-tuned," but I found out this was just his assumption. It's stock and running great in Seattle at sea level. It ran great in the mountains too.
Thanks for the input.
On the high altitude tuning -- seller thought it'd been "re-tuned," but I found out this was just his assumption. It's stock and running great in Seattle at sea level. It ran great in the mountains too.
Thanks for the input.
Team Owner
Joined: Apr 2001
Posts: 22,267
Likes: 3
From: Dallas TX
Re: Tuning for high altitude? (rideklein)
Well, I bought the car afterall. It's a 93 6spd with only 31k miles. Made for a nice roadtrip between Denver and Seattle. Thankfully, the winter weather was cooperative -- sunny skies and dry roads.
On the high altitude tuning -- seller thought it'd been "re-tuned," but I found out this was just his assumption. It's stock and running great in Seattle at sea level. It ran great in the mountains too.
Thanks for the input.
On the high altitude tuning -- seller thought it'd been "re-tuned," but I found out this was just his assumption. It's stock and running great in Seattle at sea level. It ran great in the mountains too.
Thanks for the input.
