Is partial boost possible at part throttle with a Procharger?
Thread Starter
Joined: Nov 2001
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From: Doylestown PA
Is partial boost possible at part throttle with a Procharger? Okay, a little background first.
I'm in the process of putting together a D1SC with a FMIC for my car. My current FI experience is only with my daily driver which is a Saab 9-3 that has a turbo charged 4-cylinder. With that, I don't have to give it too much throttle to start making boost, which makes the car quite lively, especially for a 2.0L 4 cylinder.
So I was wondering. Is there a way to have a procharger make boost at part throttle conditions or is it a WOT or nothing type thing? From what my understanding is, what regulates when you get boost is the Pro-Flo valve, which is vacum operated, so it stays open when you are under vacum but then closes once you go WOT. Is there a way to make that close sooner? I'm sure there is a way, but has anyone done it?
Thanks.
I'm in the process of putting together a D1SC with a FMIC for my car. My current FI experience is only with my daily driver which is a Saab 9-3 that has a turbo charged 4-cylinder. With that, I don't have to give it too much throttle to start making boost, which makes the car quite lively, especially for a 2.0L 4 cylinder.
So I was wondering. Is there a way to have a procharger make boost at part throttle conditions or is it a WOT or nothing type thing? From what my understanding is, what regulates when you get boost is the Pro-Flo valve, which is vacum operated, so it stays open when you are under vacum but then closes once you go WOT. Is there a way to make that close sooner? I'm sure there is a way, but has anyone done it?
Thanks.
no, you have to be pretty much WOT to get any boost.
I know what you mean by the turbo giving you part throttle boost, I drove a guys EvoX and it was weird having boost at liek 60% throttle.
Don't believe there is anyway to make boost faster.
I know what you mean by the turbo giving you part throttle boost, I drove a guys EvoX and it was weird having boost at liek 60% throttle.
Don't believe there is anyway to make boost faster.
Thread Starter
Joined: Nov 2001
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From: Doylestown PA
Well that sucks. In my saab, I'm in boost at like 1/3 throttle.
So from the way it sounds, a procharger is essentially like having nitrous in that you only get the added power at WOT. If that's the case, I may need to rethink this.
So from the way it sounds, a procharger is essentially like having nitrous in that you only get the added power at WOT. If that's the case, I may need to rethink this.
Thread Starter
Joined: Nov 2001
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From: Doylestown PA
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From: Zanesfield, OH
So no boost except at WOT? I can understand maybe none at slight tip in but none at even 50% or 75% throttle. Wouldn't that make driving a low compression set up miserable unless you were WOT? If that is the case then my stock set up would feel more peppy than a procharged car except at WOT?
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Launching!
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From: Sand Springs, OK
You will have boost at 1/4, 1/2 peddle depending on what rpm you are at.
At 2000-3000 yea, I have to mat it to get boost.
at 6000, I barley touch it and it goes into boost.
at 4000, You can still give 1/4 - 1/2 and get into the boost.
At 2000-3000 yea, I have to mat it to get boost.
at 6000, I barley touch it and it goes into boost.
at 4000, You can still give 1/4 - 1/2 and get into the boost.
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Verdad Gallardo Thread Starter
Joined: Nov 2001
Posts: 10,813
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From: Doylestown PA
Ok, so boost at part throttle might not be accurate or even neccesary. My real question is lets say at normal cruise right now at 5% throttle and 2500 rpm I'm seeing ~50kpa vacum, when I add the procharger, shouldn't I see less vacum at the same conditions? Less vacum is more power, right?
So my point is this. I've got a decent NA setup right now. The cam and heads are a good combo making good part throttle power and throttle response. By adding the procharger, I should see more power/torque than I currently have even if I'm not at WOT, right?
So my point is this. I've got a decent NA setup right now. The cam and heads are a good combo making good part throttle power and throttle response. By adding the procharger, I should see more power/torque than I currently have even if I'm not at WOT, right?
buddy had a srt-4 with a 70mm turbo on it, no power under 4k but at 4500 holy you know what. car could make lane changes with the throttle the boost came on so hard.
(Sorry for the hijack - it should be a yes-no answer!) 
I have no idea what I'm talking about. But the way I see it is like this. Air will take the easiest path at low throttle that would be the bypass at part throttle some will go into the intake and the rest out the bypass. You will not be in boost because their will be no restriction but haveing the tb open will allow more air into the intake and provide more power.
Don't know if that makes any sense but seems logical to me.
Don't know if that makes any sense but seems logical to me.
You can definitely get boost at part throttle because the bypass valve is opened by vacuum, not throttle position. I see it quite often on the installs I have done.
As you roll into the throttle, the manifold vacuum can drop low enough that the bypass will close & the charger will force air into the engine, so you can get some boost at part throttle. Not a lot of boost, but it is not uncommon to see maybe 1# at 2500-3000rpm. It will make the car feel much more responsive even though it is not the same amount that the car sees at full throttle.
As you roll into the throttle, the manifold vacuum can drop low enough that the bypass will close & the charger will force air into the engine, so you can get some boost at part throttle. Not a lot of boost, but it is not uncommon to see maybe 1# at 2500-3000rpm. It will make the car feel much more responsive even though it is not the same amount that the car sees at full throttle.
Thread Starter
Joined: Nov 2001
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From: Doylestown PA
You can definitely get boost at part throttle because the bypass valve is opened by vacuum, not throttle position. I see it quite often on the installs I have done.
As you roll into the throttle, the manifold vacuum can drop low enough that the bypass will close & the charger will force air into the engine, so you can get some boost at part throttle. Not a lot of boost, but it is not uncommon to see maybe 1# at 2500-3000rpm. It will make the car feel much more responsive even though it is not the same amount that the car sees at full throttle.
As you roll into the throttle, the manifold vacuum can drop low enough that the bypass will close & the charger will force air into the engine, so you can get some boost at part throttle. Not a lot of boost, but it is not uncommon to see maybe 1# at 2500-3000rpm. It will make the car feel much more responsive even though it is not the same amount that the car sees at full throttle.
Thanks everyone for the comments.
Last edited by The Alchemist; Apr 13, 2011 at 10:21 PM.
8 sec potential, 12 sec slip
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From: Savannah, GA
Yes, for sure you can get into boost at part throttle with a procharger. Its hard because once you feel a tad bit of boost coming on, you just want to floor it and get it all 
But if you can restrict yourself to not go WOT, yes, you will still see boost, and you will feel more airflow, even if you are not into boost yet if that makes sense? Hard to describe it to someone who has not driven a procharged car, but bottom line, you will have more power throughout the whole RPM range and at any throttle position compared to any N/A setup.
But if you can restrict yourself to not go WOT, yes, you will still see boost, and you will feel more airflow, even if you are not into boost yet if that makes sense? Hard to describe it to someone who has not driven a procharged car, but bottom line, you will have more power throughout the whole RPM range and at any throttle position compared to any N/A setup. 
Thread Starter
Joined: Nov 2001
Posts: 10,813
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From: Doylestown PA
Yes, for sure you can get into boost at part throttle with a procharger. Its hard because once you feel a tad bit of boost coming on, you just want to floor it and get it all But if you can restrict yourself to not go WOT, yes, you will still see boost, and you will feel more airflow, even if you are not into boost yet if that makes sense? Hard to describe it to someone who has not driven a procharged car, but bottom line, you will have more power throughout the whole RPM range and at any throttle position compared to any N/A setup.
But if you can restrict yourself to not go WOT, yes, you will still see boost, and you will feel more airflow, even if you are not into boost yet if that makes sense? Hard to describe it to someone who has not driven a procharged car, but bottom line, you will have more power throughout the whole RPM range and at any throttle position compared to any N/A setup.99% of the time I drive my car it's on 2 lane backroads with lots of curves, twists, dips and such. So I considered going bigger cubes for a while because after looking at log after log after log of my driving, I realized that most of the time I was accelerating at between 40-50% throttle and shifting between 3500-4500 rpm. Now I know that a procharger might not be the most ideal setup, but it was something that I knew I had the skills to do in my own garage and was going to be considerably less expensive to do than a bigger cube motor.
I will still enjoy the romp to 6000+ rpm from time to time, which I know is when the procharger will shine, but I just wanted to make sure that it wasn't going to be like nitrous where it's all or nothing and only there at WOT.
You'll have a lot of fun with it! Bob
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Thread Starter
Joined: Nov 2001
Posts: 10,813
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From: Doylestown PA