Hydra Nemesis

[TomsSVX]

Originally Posted by Johnybeas

since you are using map not maf does the hydra need to be retuned every time you go to a different altitude for an extended amount of time???

extreme differences in altitude can cause the ECU to run differently yes...

Tom

[Johnybeas]

so should I wait to install it until its in Florida? how hard is it to tune for higher altitudes such as my home state (Utah)

[TomsSVX]

Originally Posted by Johnybeas

so should I wait to install it until its in Florida? how hard is it to tune for higher altitudes such as my home state (Utah)

Depends, you could simply recalibrate your barometric pressure for you current location anytime you make a drastic change in altitude. It tought to say with two very different climates like this.

Tom

[dynomatt]

Does the ECU have a table for MAP differences? That might be able to cope with altitude changes.

Matt

[TomsSVX]

No barometric sensor just the MAP. The one way you can use it to adjust to the new altitude is to recalibrate the MAP's base reading which will pick up your current barometric pressure and reset to 0.

Tom

[Sov13t]

Which by the sounds of it is pretty easy? I would imagine its just a matter of having the car not running but the key in on position and zeroing the MAP reading? with the help of a laptop of course...

-Sov13t.

[TomsSVX]

Originally Posted by Sov13t

Which by the sounds of it is pretty easy? I would imagine its just a matter of having the car not running but the key in on position and zeroing the MAP reading? with the help of a laptop of course...

-Sov13t.

Yes, thats exactly what you would need to do.

Tom

[Johnybeas]

So if I were to drive across country with the new hydra in, would it be a pain? constantly having to zero out the computer or change the pressure to 29.92 or whatever variant of the standard pressure? Is there no automatic alterations???? I mean I know with flight the barometric pressure changes with temperature and altitude. The standard barometric pressure at sea level is 29.92 but the change of temperature and humidity can change that up and down. Is there anything in the map system that will detect the pressure change??

[sperry]

I thought MAP stood for "Manifold Absolute Pressure". Doesn't the MAP sensor in the Hydra read the pressure in the intake over zero, not over barometric pressure (which would be Manifold Reliative Pressure)? Or is it a MRP sensor added to an expected base pressure, modified by the intake temp?

I never noticed a setting in the Hyrda on my WRX for resetting the base pressure, and I've never had a significant issue with fueling being screwed up at high altitude (my WRX was tuned at sea level, but Reno is a ~4,200 ft). Boost control however is a different story, because that's a relative pressure feedback system, so it's different to tune the BCS to hit target boost at altitude than at sea level, but my MAP based fuel table works fine at high altitude.

[TomsSVX]

Originally Posted by sperry

I thought MAP stood for "Manifold Absolute Pressure". Doesn't the MAP sensor in the Hydra read the pressure in the intake over zero, not over barometric pressure (which would be Manifold Reliative Pressure)? Or is it a MRP sensor added to an expected base pressure, modified by the intake temp?

I never noticed a setting in the Hyrda on my WRX for resetting the base pressure, and I've never had a significant issue with fueling being screwed up at high altitude (my WRX was tuned at sea level, but Reno is a ~4,200 ft). Boost control however is a different story, because that's a relative pressure feedback system, so it's different to tune the BCS to hit target boost at altitude than at sea level, but my MAP based fuel table works fine at high altitude.

You zero the MAP in the initial setup of the unit along with other sensors like the TPS etc... The alterations based on altitude are relatively minimal and not really that big of a deal esp in an N/A engine. Its when the car is boosted that the pressures really make a difference when it comes to boost control and fueling under full throttle etc...

You make a bigger deal out of the barometric pressure than one really needs to.

Tom

[sperry]

Originally Posted by TomsSVX

You zero the MAP in the initial setup of the unit along with other sensors like the TPS etc... The alterations based on altitude are relatively minimal and not really that big of a deal esp in an N/A engine. Its when the car is boosted that the pressures really make a difference when it comes to boost control and fueling under full throttle etc...

You make a bigger deal out of the barometric pressure than one really needs to.

Tom

Hrm.. I've reset the TPS before, as well as some of the other items in the setup menu (like the wideband calibration), but I don't remember seeing a base pressure reset...

Either way, my post was actually to point out that zeroing the base pressure was not a big deal. My WRX runs a hydra and ~22psi of boost and I never had to tweak it for high altitude. Granted, I'm running a manual boost controller, so I didn't have to tune my Hyrda's boost control maps. Tuning boost control for high altitude would probably be necessary if I was controlling the boost control solenoid via the Hydra, but even then the fuel table would probably be fine.

A quick question that might have been answered earlier (I didn't read all 5 pages), is the SVX Hyrda based on the 2.5 or 2.6 hardware? I wonder if it would be possible to pick up a 2.6 Hydra for my WRX, and have my 2.5 reconfigured for use in the SVX?

[TomsSVX]

Originally Posted by sperry

Hrm.. I've reset the TPS before, as well as some of the other items in the setup menu (like the wideband calibration), but I don't remember seeing a base pressure reset...

Either way, my post was actually to point out that zeroing the base pressure was not a big deal. My WRX runs a hydra and ~22psi of boost and I never had to tweak it for high altitude. Granted, I'm running a manual boost controller, so I didn't have to tune my Hyrda's boost control maps. Tuning boost control for high altitude would probably be necessary if I was controlling the boost control solenoid via the Hydra, but even then the fuel table would probably be fine.

A quick question that might have been answered earlier (I didn't read all 5 pages), is the SVX Hyrda based on the 2.5 or 2.6 hardware? I wonder if it would be possible to pick up a 2.6 Hydra for my WRX, and have my 2.5 reconfigured for use in the SVX?

It is based on the 2.6 firmware... It might be able to be done if you really wanted.

I understand what you are saying and I agree that fueling and timing set for sea level will not be dangerous at high altitudes for an N/A car unless you plan to go racing... At which point you will need to keep tabs on how the car changes for this altitude. No car driven regularly should be tuned on the ragged edge that altitude changes will make or break the car...

Tom

[Johnybeas]

So since the changes shouldn't be drastic enough to worry, I'd be ok if I got just the base maps and then did further tuning with a hydra tuner when I decide to turbo or do more work right???

[TomsSVX]

Originally Posted by Johnybeas

So since the changes shouldn't be drastic enough to worry, I'd be ok if I got just the base maps and then did further tuning with a hydra tuner when I decide to turbo or do more work right???

Yes that is correct

Tom

[Johnybeas]

I noticed in the picture on your website that it looks like the only connection cable to the computer is a serial cable. Is this the only way??? aren't serial cables pretty dated, I mean old printers used them but from my knowledge as far as peripherals most computers now a days don't really use inputs with serial connections, it's usually a usb or firewire connection. Correct me if I'm wrong from glancing at the picture, but what do you use to connect to your computer???

Also I had another question, if you are using the map sensor and the maf is now obsolete what did you do with the wiring for the plug?? Did you remove it or leave it for easy replacement to pass emissions??