A couple questions for the guys running superchargers in high elevations.
I am in SLC @ about 4500 feet. I purchased my SoS Stage 2 for my DBW about a month ago, and the time to install is drawing near. When I spoke to Science of Speed I let them know my horsepower goal was somewhere near 350whp, but after reviewing the parts I received from them, it occured to me that I was given the same size pulley (3.8) that is normally given with the kit.
I called SoS and explained that it is likely that given the altitude, I may lose as much as 15% whp (300 HP uncorrected) and probably 2 PSI, and while they admitted they have no tuning experience for high altitude driven superchargers, I was told that they had a hard time believing that I may lose as much as 2 PSI.
Has anyone driven 4000 feet +? How much PSI did you guys lose, if any? If I am going to need to overspin the supercharger, what size pulley do you suggest?

 

u will lose boost. when i go to the dragon theres a section where i climb to 6k feet. i lost as much as 4ish psi!

air is thinner the higher you are, and with a SC it compresses air at a finite rate, if the air is thinner, it doenst compress more of it like a turbo will.

that being said, you will need to pulley down to hit the same boost as sea level guys.

one side thing though, if you drove to sea level, there will be issues doing this. make sure the tune is scaled up in the areas you cant hit at 4500 feet.

 

Thanks for the info! I'm purchasing the smaller pulley, and keeping the larger one for scenarios I may be below 4500 feet. Thanks!

 

I have a follow-up question, not specifically to do with elevation...

The place I will have the tune done is roughly 30 miles away. After I install the supercharger and components, will the car be safe to drive the distance (well under WOT and carefully) IF I reflash the ecu with the tune from my flashpro, remove supercharger belt and drive with stock MAP sensor?
I will be running larger injectors than stock (I think 650?), but I believe the base tune should at least get me there...
I plan on installing 4bar MAP sensor and pulley belt upon arrival at the dyno shop. I will be bringing extra spark plugs and a full tank of gas as well. Any other tips/insight?

 

as long as the base tune is for 650 injectors with stock map sensor, then yeah you could take the belt off and drive NA. but if the tune is not for those things, then you will have problems.

 

I always recommend towing it to the tuner to avoid any potential issues.

 

You will lose around 2.2 psi at that elevation. Im also around 4500 ft but Im turboed. One strange thing about turbos at elevation is that they spool very quick.

 

Towing would be ideal, but I don't think I want to afford a 30 mile tow.

I suppose I'll drive out there with my s/c belt removed, and install my MAP sensor and injectors, then flash my ECU. I am assuming the walbro fuel pump won't cause any issues with stock injectors/ECU?

Sorry, I reek of noob... It's my first s/c'ed car though, and I'm trying to take every possible step to stay safe.

 

There you go And no, you wont have any issues with the pump.

 

Well, with a 3.4 pulley (downsized from the 3.8) I am still only making 6-6.5 psi. No where near my hp goal either...