19% Pulley But With 5500' Of Altitude......
#1
03-18-2005, 11:24 PM
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19% Pulley But With 5500' Of Altitude......
I've seen all the posts and graphs showing the pros and cons of a 19% pulley. I understand that a 19% pulley will not redline the supercharger as long as I don't go over the stock redline of the engine.
My question is this. One of Andy's graphs shows a 19% pulley peak air pressure of about 17.4 psi around 6600 RPM. A 15% pulley was almost 16 psi.
Are these measurements absolute air pressure? Here's why. I live in Albuquerque, NM which is about 5200' about sea level. If sea level is 14.7 psi and 5000' above sea level is 12.23 psi then I should be able to take about 2.5 psi off Andy's 19% pulley reading and get around 15 psi of boost if I install a 19% pulley. This is assuming the graphs are done around sea level.
If people are running 15% pulleys with no problems, good inter-cooler efficiently, etc. then I should be fine with a 19% pulley up here as far as intake temperature, no upgraded injectors, etc. since I would be running an estimated 15psi.
I know weather, temperature and the like play a roll in this but I wanted to get your opinions on this.
Brad
My question is this. One of Andy's graphs shows a 19% pulley peak air pressure of about 17.4 psi around 6600 RPM. A 15% pulley was almost 16 psi.
Are these measurements absolute air pressure? Here's why. I live in Albuquerque, NM which is about 5200' about sea level. If sea level is 14.7 psi and 5000' above sea level is 12.23 psi then I should be able to take about 2.5 psi off Andy's 19% pulley reading and get around 15 psi of boost if I install a 19% pulley. This is assuming the graphs are done around sea level.
If people are running 15% pulleys with no problems, good inter-cooler efficiently, etc. then I should be fine with a 19% pulley up here as far as intake temperature, no upgraded injectors, etc. since I would be running an estimated 15psi.
I know weather, temperature and the like play a roll in this but I wanted to get your opinions on this.
Brad
#2
03-19-2005, 07:31 AM
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Boost pressure
Originally Posted by nerd
I've seen all the posts and graphs showing the pros and cons of a 19% pulley. I understand that a 19% pulley will not redline the supercharger as long as I don't go over the stock redline of the engine.
My question is this. One of Andy's graphs shows a 19% pulley peak air pressure of about 17.4 psi around 6600 RPM. A 15% pulley was almost 16 psi.
Are these measurements absolute air pressure? Here's why. I live in Albuquerque, NM which is about 5200' about sea level. If sea level is 14.7 psi and 5000' above sea level is 12.23 psi then I should be able to take about 2.5 psi off Andy's 19% pulley reading and get around 15 psi of boost if I install a 19% pulley. This is assuming the graphs are done around sea level.
If people are running 15% pulleys with no problems, good inter-cooler efficiently, etc. then I should be fine with a 19% pulley up here as far as intake temperature, no upgraded injectors, etc. since I would be running an estimated 15psi.
I know weather, temperature and the like play a roll in this but I wanted to get your opinions on this.
Brad
My question is this. One of Andy's graphs shows a 19% pulley peak air pressure of about 17.4 psi around 6600 RPM. A 15% pulley was almost 16 psi.
Are these measurements absolute air pressure? Here's why. I live in Albuquerque, NM which is about 5200' about sea level. If sea level is 14.7 psi and 5000' above sea level is 12.23 psi then I should be able to take about 2.5 psi off Andy's 19% pulley reading and get around 15 psi of boost if I install a 19% pulley. This is assuming the graphs are done around sea level.
If people are running 15% pulleys with no problems, good inter-cooler efficiently, etc. then I should be fine with a 19% pulley up here as far as intake temperature, no upgraded injectors, etc. since I would be running an estimated 15psi.
I know weather, temperature and the like play a roll in this but I wanted to get your opinions on this.
Brad
I'd bet those numbers you mentioned were sealevel boost pressures and your recalculations for our altitude in Abq are correct. From my past experience with my blown mustang that's about the percentage diff.
Something to consider though, take a look at what mods the JCW setup does. Granted it has a reworked head that flows better but the boost is upped from .5 bar to 1 bar (14psi) and it uses larger injectors, remapped ECU as well.
I'd recommend a good A/F dyno test before I go all out if you make the pulley change w/o anything else.
Wayne
#4
03-19-2005, 09:53 AM
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Originally Posted by ripley
snif, snif. what are you up to?
ripley
ripley
I'm planning out my upgrades for when my Mini gets here. Pulley will probably be the first one but a couple gauges will come before that so I can see the difference the pulley is doing. I've also thought about wide band O2 sensor but that might have to wait a while.Have you gone out on the rides with NMMini.org? If so how are the people and rides? My girlfriend and I are taking her Mini to Carlsbad Caverns and White Sands this weekend. We'll have some of the family following in a mini-van so it'll be a slow trip.
Brad
Last edited by nerd; 03-19-2005 at 09:57 AM. Reason: spelling
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