I'm going to sound like a jerk here, but here goes anyway.

If you can't "afford" a 30mile tow, either by someone else, or you renting a U-Haul trailer/dolley/etc and borrowing a buddies truck then you shouldn't be modding your car. Sounds like money is pretty tight.

What you are doing will work, I just always play it safe and tow mine, which is 2.5hrs to my tuner.

 

what boost did you hit on the 3.8 pulley? might need to pulley down even more.

 

I also live in the SLC area. Here's my thread on the topic:
https://www.s2ki.com/forums/index.php?showt...&#entry17237416

And here's some info:

Guys, I live in Salt Lake City, UT. My car hasn't seen altitude below 4500ft ASL in a few years and my stock MAP sensor is reading lower than normal boost levels as a result. This is fine and expected. The car runs great up here.

Current Setup:
Stock HG F20C
Comptech SC/AC (Novi 1000)
3.6" SOS pulley
AEM EMS
750cc RC Injectors
Header back exhaust & TP - 70mm(could also contribute to my lower boost readings)
No belt slip, I am positive.

My question:
I am considering purchasing SOS's 3.0 inch (good for 12psi on the 2.0L) pulley for the Comptech Supercharger. I want to know if I'll be needing to upgrade my MAP sensor. Right now, I am running the SOS 3.6 inch pulley and I am seeing about 7 psi of peak boost according to my AEM.

I believe the stock MAP sensor is good until 11 psi. I was wondering if anyone with a similar setup is boosting at altitude and if they found at MAP sensor upgrade to be necessary.

Here's my math, can an engineer please verify:

At 5000 ft ASL, air is 85% as dense as it would be as sea level (-3.0% for every 1000ft). So, in theory, my 3.6" pulley which, according to SOS, should see about 9psi at sea level, should see .85 * 9.0 = 7.65psi of boost at peak. The 3.0 inch pulley is said to make 12 psi on the 2.0L at peak and should see .85 * 12 = 10.2 psi of absolute pressure.

QUOTE (S2K-F8 @ Oct 1 2009, 01:05 PM)
I'm in Denver and I'm running the SOS 3.2" pulley on my CTSC. The highest boost I've seen with this setup is 9.3lbs (damn altitude biggrin.gif )

Scott-

Well, the relative boost pressure is still what it would be at sea level. Absolute pressure, which is what your manifold and boost gauge read, is lower. So, in a forced induction setup you lose less performance than you would think under boost. I know there's a mathematical calculation for this but I believe that under boost we are over 90% as efficient as you would be at sea level.

So yeah, we lose a little less than 10% (under boost, 15% NA) at 5000 ft BUT there are advantages. Because your dynamic compression ratio drops at altitude we can, theoretically, run more boost safely than you could at sea level. As long as we're not heat soaking because we're over spinning the blower, we should be able to compensate for the lost power by running slightly more aggressive setups. For me, it means I will be tracking a 13 psi setup haaaard without fear of blowing her up.

Granted, I'd rather have that power back at a lower blower rpm to help keep temps down, but it's the best we can do this high up. We do get to ski some bitchin' powder out here, though. smile.gif

 

Two words - Belt slip, or boost leak. No way you are losing 4+ psi on elevation alone. What are you at 15,000'?. That 3.4" pulley if it is indeed that size will deliver 10-11psi. I would expect 1-2 psi loss at elevation max.

 

wait until you get to the dyno to change the injectors, just run it on the stock ecu w/the belt off the supercharger

 

Looks like I overlooked something, sorry fellas. I installed my gauge (a Zeitronix boost/afr combo) and I didn't realize that my static pressure was reading -4.9, my apologies.
So static pressure in SLC is -2.5, mine is reading -4.9 for whatever reason... Either way 6-6.5 psi plus the 2.4 my gauge is off by, so boost is practically dead on.
Ran it on the dyno yesterday, my baseline wasn't impressive. I have a tune scheduled Monday at least, hopefully I'll make up something there

 

Hey Courage,
do you mind me asking how much power you made corrected/uncorrected?

 

Ahhh