Project101

Hi

I have searched this quite a bit with no real solid answer.
Can a SD tune be used on say a ls1 powered jeep that will see large elevation changes and still run good?

Thanks.

Michael Yount

iTrader: (1)

Sure. OEM's still use SD -- plenty of pickups and Jeeps with Chrysler hemis in 'em - all speed density.

Project101

Awsome,
yeah I searched Sd tune vs maf and a ton of stuff popped up and it turned into a weird argument it seemed on what the best option would be.
And a few people chimed saying that Sd tune was great as long as you were not changing elevation . I'll be using HPtuners btw if that makes a difference ,

Michael Yount

iTrader: (1)

The trick, as always, is the quality of the tune.

murphinator

iTrader: (2)

I have never tuned for elevation being here at sea level but would think as long as you use scan data from all altitudes you plan on running at so you have accurate modeling it should work.

redtan

iTrader: (5)

As others mentioned, it will be fine. A proper SD tune has ways to adjust fueling for different atmospheric conditions, so going from sea level to the top of mount washington is not going to affect how the car drives.

Michael Yount

iTrader: (1)

MAP sensor - manifold absolute pressure - it will "see" lower atmospheric pressure's impact on manifold pressure and adjust accordingly, provided the ecu's internal map of possible pressures accommodates the pressure at whatever altitudes you'll be at. With a good tune drivability shouldn't be an issue, although of course you'll see reduced output with decreasing atmospheric pressure.

conan

iTrader: (5)

I live at 6,500 ft and with in a 30 min drive I can go down to the valley that is in the 4,500 ft range or I can drive farther up the hill to a summit of 10,800 ft. I don't ever have any issues at any elevation with my SD tune.

gametech

iTrader: (1)

That is totally unnecessary, as the MAP sensor's sole purpose for existing is to measure pressure, and the IAT measures temperature, which are the only relevant things to change with altitude. The only currently used EFI system that is affected by altitude is Alpha N, which is only still used on motorcycles at this point. Even that crude system is affected a lot less than you might imagine.

Project101

I'm currently on a work trip and will be gone for a few months I'll be using hp tuners which I'm new to. But that is some great info. I haven't got into the tune yet much ,for only tire size gear ratio/ turn of vats and rear o2s . I just got it on the road before I left with an N/A setup ....all stock lol. I plan on going forced induction. And have a few months to read and learn. Before I start swinging.

And whith that how important is a dyno for tuning vs street ?

gametech

iTrader: (1)

Less cops take an interest in your time on the dyno vs on the street. Otherwise, street tuning is typically better.
edit-- your traffic and wildlife hazards may vary