wastegate with centri blower?
Originally Posted by engineermike
kp, I always value your test data because a) your car is very consistent and b) you understand the concept of keeping everything else the same.
Increasing inlet pressure on a compressor will almost always result in a net increase in flow and discharge pressure. I've seen positive results in the past by reducing compressor inlet restriction. However, if the compressor is near "choke flow" or "stonewall", then increasing suction pressure in an attempt to produce more flow will result in a reduction in efficiency, increase in discharge temp, and increase in hp required to drive the compressor. To me, yours has tell-tale signs that you are at the flow limit of the D1. Do you have any idea what the mm size of the compressor eye is?
Mike
Increasing inlet pressure on a compressor will almost always result in a net increase in flow and discharge pressure. I've seen positive results in the past by reducing compressor inlet restriction. However, if the compressor is near "choke flow" or "stonewall", then increasing suction pressure in an attempt to produce more flow will result in a reduction in efficiency, increase in discharge temp, and increase in hp required to drive the compressor. To me, yours has tell-tale signs that you are at the flow limit of the D1. Do you have any idea what the mm size of the compressor eye is?
Mike
I'm not sure on the eye meaurements but I'm sure the compressor is near being maxed ou, at least for my IC setup anyhow. If I had an A2W I'm sure I could pick up more by spinning the D1 faster, as of now adding 6K of impeller speed (3.7 to 3.4 pulley) nets me 2 psi peak and 1mph in the 1/4. That same 6K increase in impeller speed (from 4" to 3.7" pulley) nets me 3.5psi and 8mph in the 1/4
This has been very interesting reading. Im no math expert, nor have I tried using any sort of boost limiter with a supercharger. But I value hard numbers to back-up or challenge a theory.
Mike - when you get back, please do go over the spreadsheet with your magic. I'd really like to see what you come up with.
kwiksilverz - you've seen the math/scientific side of the story, youve seen other peoples results, now the only thing left is to TEST this theory and report back with hard results. I'd like to see how well it does or doesnt do.
I personally dont think you'll get much of a gain outta that P1 though. If you were restricting the peak boost of a D1 I could imagine alot of new found under the curve power.
To me this idea would be best suited for someone buying a huge blower and putting it on a stock motor temporarily untill a new motor is needed. Basically buying parts for a badass setup, but finding a way to use them on a stock based setup.
Mike - when you get back, please do go over the spreadsheet with your magic. I'd really like to see what you come up with.
kwiksilverz - you've seen the math/scientific side of the story, youve seen other peoples results, now the only thing left is to TEST this theory and report back with hard results. I'd like to see how well it does or doesnt do.
I personally dont think you'll get much of a gain outta that P1 though. If you were restricting the peak boost of a D1 I could imagine alot of new found under the curve power.
To me this idea would be best suited for someone buying a huge blower and putting it on a stock motor temporarily untill a new motor is needed. Basically buying parts for a badass setup, but finding a way to use them on a stock based setup.
Originally Posted by engineermike
I took a quick look at the spreadsheet and picked out a couple of errors. First, T1 should be ambient temp, or around 540 R. T2 seems too high also, as 863 R converts to 400 deg F. The flow of 107 lb/min equates to about 1160 hp. Is this right? Also, I didn't see any enthalpy numbers. I wish I could take a closer look or make my own spreadsheet, but I'm going out of town today and not coming back until Friday.
I can send you the Excel file to give u a head start. I found that enthalpy = H = E + P*V where E is Internal Energy, P is pressure and V is volume. The problem is that im not really sure what units to use to make it give the right numbers.
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KP - I should reiterate that what I was saying is that bleeding off boost that you've already made is not a good idea unless you're goal is strictly temporarily limiting power at the dragstrip as the losses are very high.
Restricting the inlet should not induce extra effort up to the point where you could measure the inlet restriction in the tube between the restriction and inlet to the supercharger. The efficiency of the supercharger should decrease as the inlet restriction increases as the charger is running over its air more times to produce the same airflow level as the available volume is less to feed it as rpm increases.
Restricting the inlet should not induce extra effort up to the point where you could measure the inlet restriction in the tube between the restriction and inlet to the supercharger. The efficiency of the supercharger should decrease as the inlet restriction increases as the charger is running over its air more times to produce the same airflow level as the available volume is less to feed it as rpm increases.
Originally Posted by andereck
KP - I should reiterate that what I was saying is that bleeding off boost that you've already made is not a good idea unless you're goal is strictly temporarily limiting power at the dragstrip as the losses are very high.
Restricting the inlet should not induce extra effort up to the point where you could measure the inlet restriction in the tube between the restriction and inlet to the supercharger. The efficiency of the supercharger should decrease as the inlet restriction increases as the charger is running over its air more times to produce the same airflow level as the available volume is less to feed it as rpm increases.
Restricting the inlet should not induce extra effort up to the point where you could measure the inlet restriction in the tube between the restriction and inlet to the supercharger. The efficiency of the supercharger should decrease as the inlet restriction increases as the charger is running over its air more times to produce the same airflow level as the available volume is less to feed it as rpm increases.
So you are saying that doesnt work as well as some claim? My experience with the inlet hat (assuming its a slight restriction) would support the 'flattening out the boost' theory but I have a feeling its more to do with the blower just running out of steam up top then the restriction of the filter/hat.
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No, I'm not saying that doesn't work. I'm just saying its not a free lunch up top. What I'm saying is that the X psi delivered under restriction up top is going to be hotter than the X psi delivered at a lower rpm. That's all.
Now how much hotter? I don't have data on that. Its something I would be willing to experiment with after I get some other issues settled out.
Now how much hotter? I don't have data on that. Its something I would be willing to experiment with after I get some other issues settled out.
Originally Posted by andereck
No, I'm not saying that doesn't work. I'm just saying its not a free lunch up top. What I'm saying is that the X psi delivered under restriction up top is going to be hotter than the X psi delivered at a lower rpm. That's all.
Now how much hotter? I don't have data on that. Its something I would be willing to experiment with after I get some other issues settled out.
Now how much hotter? I don't have data on that. Its something I would be willing to experiment with after I get some other issues settled out.
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Wow, this got interesting 
. Lots of valid points. I think based on the luck that many have had doing it, that the temp increase apparently isn't enough to hurt. I think it is also that a lot of us are running Alky injection, so the temps probably aren't a big issue to us.
Once I get my car back together, I'm going to get some tuning done and I'll do some back to back testing with one pulley at 12 psi and then the smaller pulley and restrictor. I have a feeling that the peak HP will be very close, regardless of parasitic loss and heat from the blower, but the mid range gains will be well worth any trade off there may be.
I have to admit, I am not into the "math" side of things, I did have an interest in engineering years ago, but saw first hand that just because it looks perfect in formula- it doesn't mean that the "wrong" way won't work better in practice. Since then, I have just gone with common sense and experience and it has worked well for me to this point. Thanks for all the input guys!
Joe
. Lots of valid points. I think based on the luck that many have had doing it, that the temp increase apparently isn't enough to hurt. I think it is also that a lot of us are running Alky injection, so the temps probably aren't a big issue to us.Once I get my car back together, I'm going to get some tuning done and I'll do some back to back testing with one pulley at 12 psi and then the smaller pulley and restrictor. I have a feeling that the peak HP will be very close, regardless of parasitic loss and heat from the blower, but the mid range gains will be well worth any trade off there may be.
I have to admit, I am not into the "math" side of things, I did have an interest in engineering years ago, but saw first hand that just because it looks perfect in formula- it doesn't mean that the "wrong" way won't work better in practice. Since then, I have just gone with common sense and experience and it has worked well for me to this point
. Thanks for all the input guys!Joe
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Brett Foote Thread Starter
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From: Port Charlotte, FL
Originally Posted by kp
Gotcha, I was under the impression that the less air to compress at high rpm with a restrictor = less heat. But it makes sense about the air running itself over. When I put the F1A on I may fool around with some restrctiction to see what happens, I may try running it this weekend..
Joe
Originally Posted by kwiksilverz
If you wanted to call ECS, they have the restrictors in stock- though, it isn't a difficult piece to make either.
Joe
Joe
True, true.. we kicked *** this year using ignition timing vs. elapsed time via the nitrous controller in the FAST. It worked really good on all but the very worst tracks..
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so let me get this straight.....lets say you pulley for 10 psi for 6200rpm. car makes 560rwhp. linear increase in the graph 420lbs of torque at 4000 rpms.
now you pulley for 14 psi for 6200 rpms but restrict it or bleed of 4 psi so again your at 10 psi at 6200rpm. would you make 560rwhp again or not? i know the 420 lbs of toque should be lower in the rpm range now. or are you saying because the blower is spinning faster creating more heat and causing more drag that at 6200 rpm you will only make 512.4 rwhp. for the 14 psi you turned down to 10?
even if above is true. depending on the changes to the area under the curve and the gains sooner and lower in the rpm range as far as the strip is concerned you may actually gain et and mph if you have a decent average increase with the sacrafice at peak?
"the numbers are fictional and used strictly for comparison purposes only. no warranties or guarantees implied, rules and regulations subject to change without notice."
now you pulley for 14 psi for 6200 rpms but restrict it or bleed of 4 psi so again your at 10 psi at 6200rpm. would you make 560rwhp again or not? i know the 420 lbs of toque should be lower in the rpm range now. or are you saying because the blower is spinning faster creating more heat and causing more drag that at 6200 rpm you will only make 512.4 rwhp. for the 14 psi you turned down to 10?
even if above is true. depending on the changes to the area under the curve and the gains sooner and lower in the rpm range as far as the strip is concerned you may actually gain et and mph if you have a decent average increase with the sacrafice at peak?
"the numbers are fictional and used strictly for comparison purposes only. no warranties or guarantees implied, rules and regulations subject to change without notice."
Originally Posted by Brady
so you need a wastegate to dump boost down low... here we go again
Yhe BS3 has timers to control a PWM boost controller solenoid (turbo or maybe a WG on a blower) but no timing adjustments vs time..
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Originally Posted by ZDOG
10 psi for 6200rpm. car makes 560rwhp. now you pulley for 14 psi for 6200 rpms but restrict it or bleed of 4 psi so again your at 10 psi at 6200rpm. would you make 560rwhp again or not?
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Originally Posted by kwiksilverz
I'm going to get some tuning done and I'll do some back to back testing with one pulley at 12 psi and then the smaller pulley and restrictor.
Mike
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From: Port Charlotte, FL
Originally Posted by engineermike
I urge you to make at least 1 dyno pull with the smaller pulley and no restrictor.
Mike
Mike
No doubt it will make more peak power without the restrictor, but the "under the curve" power will more than likely be the same with or without, if not- close.
I'm not going to have my car back together until the nice weather hits, so it's going to be a while
.Joe
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Originally Posted by kwiksilverz
but the "under the curve" power will more than likely be the same with or without, if not- close.