Altitude Considerations

[nikolai]

So I live around Denver (~5280ft). I checked an online calculator and it says my atmospheric pressure is 12.14psi at 75F. That's roughly 2.5psi below atmosphere at sea level. So if I were considering something like Procharger kit (I am) which I think comes with a 9psi pulley, I'd have to pulley up to 11.5psi to get the same power. How do I calculate the expected pressure that a pulley can produce? I see lots of online calculators for that, but they all ask for various parameters about the car, that I don't know how to answer.
My second question is about head unit sizing. Let's assume I'm going to focus on offerings from Procharger. Initially, I'd want to run lower power to give myself time to sort gremlins, but I'd want to size the head unit to max out on E85 up to 800-900hp (I doubt I'd actually push it that far). A P1SC is rated at 825, but that's likely only on race fuel and at sea level. Should I just start with something like a D1X knowing I will need to run more boost from the get-go? Is there a limit to how much power I can get on E85 (timing limited I suppose)?

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[Angry50]

I hear the p1x is the unit of choice. i think the recommend the d1x if going over 900

 

[Jay-rod427]

P1SC-1<P1X<D1SC<D1X. For turning it up that much, and altitude consideration I would prob look at atleast the D1SC, if not the X. If you order from/talk to Procharger they will give you pulley recommendations for your altitude, but since you plan on E85 will need to find a custom tune to turn up the boost, and E85. Is your E85 close to 85%?

 

[Roush05]

Boost is going to depend on more than your pulley. An excerpt from https://www.928motorsports.com/services/selectingpulley.php#Impeller_Speed_Calculator:


"
The boost gauge measures pressure. Pressure is caused by a restriction to flow. The engine is that restriction to flow.
While the supercharger is spinning and making up air, the engine is also running and inhaling, and the boost gauge only shows the remainder. In other words: The boost gauge only shows WHAT'S LEFT after the engine consumes what it can.

Supercharger output MINUS engine consumption = what's left to display on the gauge.

Sometimes we get a call from an enthusiast who has just added headers, or cams, or a larger intake and now sees his boost gauge is lower than it used to be. They call thinking they did something wrong. Quite the opposite – they have removed restrictions to air flow in their motor, and although the supercharger is producing as much air as it did before, the engine can now use more of it. The HP of this engine has gone up, and the boost gauge will have gone down. "

Basically you probably won't find an accurate calculator online because if you have any intake/exhaust modifications done then you would make less boost on the same pulley as a stock car, albeit with more power.

 

[nikolai]

P1SC-1<P1X<D1SC<D1X. For turning it up that much, and altitude consideration I would prob look at atleast the D1SC, if not the X. If you order from/talk to Procharger they will give you pulley recommendations for your altitude, but since you plan on E85 will need to find a custom tune to turn up the boost, and E85. Is your E85 close to 85%?

I know there are several stations around here with E85, but I've not tested it to see if it's actually 85%. I know I'll eventually have to run E85 because it's only 91 octane here. That coupled with the higher boost requirements, means I'll need better fuel pretty soon.

 

[Jay-rod427]

I know there are several stations around here with E85, but I've not tested it to see if it's actually E85. I know I'll eventually have to run E85 because it's only 91 octane here. That coupled with the higher boost requirements, means I'll meed better fuel pretty soon.

I'd be curious to know what % is provided up there during the summer. Will no doubt drop come winter blend so be careful and test often when pushing hard.

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