Boost experts questions
Thread Starter
Melting Slicks
Joined: Nov 2003
Posts: 3,011
Likes: 9
From: Dublin GA
Boost experts questions
For the experts here that know what affects boost, I have a question about my set up. My mods are in my sig, but I have a H/C with all the supporting mods, ( 10.7 cr)
I have the P1SC1 with the stock 4.75" pulley and updated bracket. It has the smaller 3 1/2" intercoolers (with 2 1/2" inlets) and 2 1/2" plumbing. I am updating to a over the radiator 4" inlet pipe with the large A&A air filter. I will also run a low restriction 3 1/2" pipe from MAF to TB. My questions are;
1. How will the increased airflow affect the boost (Stage II runs a 4 1/2" pulley for same boost)
2.What is the MAX boost I should run with my set up? (I plan on running meth)
I have the P1SC1 with the stock 4.75" pulley and updated bracket. It has the smaller 3 1/2" intercoolers (with 2 1/2" inlets) and 2 1/2" plumbing. I am updating to a over the radiator 4" inlet pipe with the large A&A air filter. I will also run a low restriction 3 1/2" pipe from MAF to TB. My questions are;
1. How will the increased airflow affect the boost (Stage II runs a 4 1/2" pulley for same boost)
2.What is the MAX boost I should run with my set up? (I plan on running meth)
Tech Contributor
Joined: Apr 2007
Posts: 10,924
Likes: 78
From: Forney Texas
For the experts here that know what affects boost, I have a question about my set up. My mods are in my sig, but I have a H/C with all the supporting mods, ( 10.7 cr)
I have the P1SC1 with the stock 4.75" pulley and updated bracket. It has the smaller 3 1/2" intercoolers (with 2 1/2" inlets) and 2 1/2" plumbing. I am updating to a over the radiator 4" inlet pipe with the large A&A air filter. I will also run a low restriction 3 1/2" pipe from MAF to TB. My questions are;
1. How will the increased airflow affect the boost (Stage II runs a 4 1/2" pulley for same boost)
2.What is the MAX boost I should run with my set up? (I plan on running meth)
I have the P1SC1 with the stock 4.75" pulley and updated bracket. It has the smaller 3 1/2" intercoolers (with 2 1/2" inlets) and 2 1/2" plumbing. I am updating to a over the radiator 4" inlet pipe with the large A&A air filter. I will also run a low restriction 3 1/2" pipe from MAF to TB. My questions are;
1. How will the increased airflow affect the boost (Stage II runs a 4 1/2" pulley for same boost)
2.What is the MAX boost I should run with my set up? (I plan on running meth)
Question #2 may cause a friendly discussion since some are comfortable with running more boost than others and have gotten away with it for significant periods of time. With meth and a proper tune, you can easily run 10psi, but should be able to get away with a few #'s more if you care to push things a little harder. Tuning is key. I think Mr.Big has been running around 14+psi (I'm quite sure it's not less) in his stock LS2 for many years/miles now with no issues. He has a great tuner named Taylor Sims at Dallas Performance.
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Joined: Jul 2006
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From: Simi Valley CA
Also, what Bret touched on, is that there are two factors to "boost". One is pressure, the other is volume. The smaller the tubing with the same amount of volume will produce more pressure. Larger tubing acts like larger valves, high lift cams, etc.. in that the boost pressure will drop.
Being you have a cam, you can't really use the "xx size pulley is zz psi" thing. Best thing is to take a look at someone who is running the same cam/heads and gauge off that. YMMV anyway.
Like anything else in hot rodding.. start small and work up. In this case, use the larger pulley you have, and see what kind of boost you get off it. Smaller pulley later (which may lead to belt slip problems too). I'm running the same blower as you, and a 4.10 pulley (stock Z06 cam). I get 7lbs boost at 6k.
Being you have a cam, you can't really use the "xx size pulley is zz psi" thing. Best thing is to take a look at someone who is running the same cam/heads and gauge off that. YMMV anyway.
Like anything else in hot rodding.. start small and work up. In this case, use the larger pulley you have, and see what kind of boost you get off it. Smaller pulley later (which may lead to belt slip problems too). I'm running the same blower as you, and a 4.10 pulley (stock Z06 cam). I get 7lbs boost at 6k.
Last edited by Todd157k; Jan 19, 2009 at 11:22 PM.
Former Vendor
Joined: Dec 2006
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How much boost the blower can produce depends on many variables.
* Cubic inch. The larger the engine the less boost it will make with a P-1SC.
* Headers and exhaust. A better flowing system will produce less boost, requires a smaller pulley to regain the loss in boost. Ultimately though, more power will be gained.
* Camshaft and heads. A camshaft with some overlap will leak out some boost through the valves. Better flowing heads react a lot like a better flowing exhaust system.
* Altitude. Elevation plays a big part in how much boost is produced. Those people living in the higher elevations have to spin the blower harder to see boost.
* Condition of engine. An engine with real good sealing rings will ultimately produce more boost than one with worn rings.
* Rpm. An engine that is spun up higher in the rpm range will normally produce more boost.
ProCharger spec's out the blower pulley based on the above information. Bob
* Cubic inch. The larger the engine the less boost it will make with a P-1SC.
* Headers and exhaust. A better flowing system will produce less boost, requires a smaller pulley to regain the loss in boost. Ultimately though, more power will be gained.
* Camshaft and heads. A camshaft with some overlap will leak out some boost through the valves. Better flowing heads react a lot like a better flowing exhaust system.
* Altitude. Elevation plays a big part in how much boost is produced. Those people living in the higher elevations have to spin the blower harder to see boost.
* Condition of engine. An engine with real good sealing rings will ultimately produce more boost than one with worn rings.
* Rpm. An engine that is spun up higher in the rpm range will normally produce more boost.
ProCharger spec's out the blower pulley based on the above information. Bob
Thread Starter
Melting Slicks
Joined: Nov 2003
Posts: 3,011
Likes: 9
From: Dublin GA
Thanks guys.
So as I make the engine more efficient, (which is of course what make hp) I actually cause the boost (for a certain pulley, or blower rpm) to decrease. I would then have to decrease the pulley size to increase boost
Can procharger (or anyone) give me a educated guess as to what the boost would be if I provided the details (camshaft specs, altitude etc.?)
This is why I ask; I have no tuner with extensive blower experience within 6 hrs of me. So when I get this thing bolted on, I am probably going to have to trailer the car to him. If I get there and we wind up with 3psi of boost, then I've got to take it back home and send it off to swap pulleys. If I get there and make 12psi and 625rwhp (NOT GONNA HAPPEN
) I've got to do the same thing.
I don't want to built so much boost and hp that I've just got a grenade waiting to blow, but I don't want to spend this much money to make less hp than I did with N2O (563)
1.So I need to find out someone that has this combo, or someone (procharger?) that can help me get in the ballpark, so I can make a change (if neccesary) before I make the tuning trip
I am aiming on making around 575-590rwhp with a nice safe tune
2.Do you think the smaller intercoolers and plumbling will keep me from hitting this?
So as I make the engine more efficient, (which is of course what make hp) I actually cause the boost (for a certain pulley, or blower rpm) to decrease. I would then have to decrease the pulley size to increase boost
Can procharger (or anyone) give me a educated guess as to what the boost would be if I provided the details (camshaft specs, altitude etc.?)
This is why I ask; I have no tuner with extensive blower experience within 6 hrs of me. So when I get this thing bolted on, I am probably going to have to trailer the car to him. If I get there and we wind up with 3psi of boost, then I've got to take it back home and send it off to swap pulleys. If I get there and make 12psi and 625rwhp (NOT GONNA HAPPEN
) I've got to do the same thing.I don't want to built so much boost and hp that I've just got a grenade waiting to blow, but I don't want to spend this much money to make less hp than I did with N2O (563)
1.So I need to find out someone that has this combo, or someone (procharger?) that can help me get in the ballpark, so I can make a change (if neccesary) before I make the tuning trip
I am aiming on making around 575-590rwhp with a nice safe tune
2.Do you think the smaller intercoolers and plumbling will keep me from hitting this?
