Supercharged - Boost controller ?
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Joined: Jul 2012
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My name is Carl and I am from 928 Motorsports.
I thought I would see if I can answer some of your questions if I can.
99SH: your graph is interesting, but it does not show that the BLV is "not working". In order to do that, it needed one more pull with the BLV removed. Then you would see a dyno pull with the BLV removed and the BLV installed, and THEN we would see how much it did, or if it was working at all. I suspect as before that it is working, but not large enough to do the job at hand. The engine in the S2000 is pretty small, and the supercharger you are using at 1200 CFM is intended for a V8. I have no doubt it builds boost like crazy.
Remember: boost represented on the boost gauge is NOT a indicator of supercharger output, it is an indicator of restriction to flow. Only restriction to flow (backpressure) builds boost that the gauge is measuring. In your case, the big blower ont he small engine has all kinds of restriction to flow, and it builds boost even with the BLV open and the engine drawing air at full throttle.
Suggestions: use a larger SC drive pulley to slow the supercharger down; use a smaller supercharger that is better matched to the task (the bigger blower has higher parasitic loss at the crank); or modify the engine with items to make air flow through the engine better (which will also make more HP) such as: larger throttle body, more agressive cams, headers and exhaust mods, etc.
I agree with you that the BLV that we make is way to small for the task you have given it. If left as-is, a turbo waste gate, modified to work on a supercharger, will dump more air. You have to decide whether all those parasitic losses (the load on the engine to turn the blower just to blow the air opff to atmosphere) is worth it.
My friend Corky Bell has an excellent book called "Supercharged!": at Amazon books and it is very informative about these things.
Hope this helps, and feel free to contact me if I can be of service.
Carl Fausett
Member S.A.E.
928 Motorsports, LLC
I thought I would see if I can answer some of your questions if I can.
99SH: your graph is interesting, but it does not show that the BLV is "not working". In order to do that, it needed one more pull with the BLV removed. Then you would see a dyno pull with the BLV removed and the BLV installed, and THEN we would see how much it did, or if it was working at all. I suspect as before that it is working, but not large enough to do the job at hand. The engine in the S2000 is pretty small, and the supercharger you are using at 1200 CFM is intended for a V8. I have no doubt it builds boost like crazy.
Remember: boost represented on the boost gauge is NOT a indicator of supercharger output, it is an indicator of restriction to flow. Only restriction to flow (backpressure) builds boost that the gauge is measuring. In your case, the big blower ont he small engine has all kinds of restriction to flow, and it builds boost even with the BLV open and the engine drawing air at full throttle.
Suggestions: use a larger SC drive pulley to slow the supercharger down; use a smaller supercharger that is better matched to the task (the bigger blower has higher parasitic loss at the crank); or modify the engine with items to make air flow through the engine better (which will also make more HP) such as: larger throttle body, more agressive cams, headers and exhaust mods, etc.
I agree with you that the BLV that we make is way to small for the task you have given it. If left as-is, a turbo waste gate, modified to work on a supercharger, will dump more air. You have to decide whether all those parasitic losses (the load on the engine to turn the blower just to blow the air opff to atmosphere) is worth it.
My friend Corky Bell has an excellent book called "Supercharged!": at Amazon books and it is very informative about these things.
Hope this helps, and feel free to contact me if I can be of service.
Carl Fausett
Member S.A.E.
928 Motorsports, LLC
Former Sponsor
Joined: Oct 2007
Posts: 28,698
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From: Mooresville, NC
Why would he want to use a smaller blower? The 1200 is awesome for the S2000. Whole point was to build boost quicker and bleed off after the target boost level is hit it appears. Going to a smaller blower to produce less boost is a ridiculous suggestion as he will be building much less boost down low and midrange.
1200 makes some awesome power on this car!
Can't wait to see the results with the wastegate.
OP where are you going to be mouting the wastegate?
1200 makes some awesome power on this car!
Can't wait to see the results with the wastegate.
OP where are you going to be mouting the wastegate?
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Joined: Jul 2012
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Let's talk supercharger high speed seals (impeller shaft seals) for a minute...
There are two kinds: the face seal (which is what Vortech installs OEM) and a lip seal. Ours is a twin-lip seal.
As you know, they both fail. The OEM face seal leaks too after a time, and that's why you went looking for and found our twin-lip seal.
However: be sure that the seal is the real problem, and not just a symptom of a different problem.
Attach a boost pressure gauge to your crankcase temporarilly under load and see how much crankcase pressure you are building.
You might find the underlying cause for why your impeller shaft seals are weeping.
The Vortech supercharger (except the new V3 model) receives oil from the engine at about 60 to 80 psi while the engine is running.
Yet the drain is gravity only, and the oil in the supercharger is now entrained with air, making it even more sluggish and difficult to drain.
If the crankcase has pressure, the oil in the supercharger cannot drain, the supercharger case builds pressure, and the seals leak.
Some tips:
1) Be sure that your oil drain out of the supercharger is in the 6:00 (straight down) position
2) be sure that the oil drain is at least 3/4" in diameter. Nothing smaller.
3) be sure that the PCV system has been modified since the supercharger was installed, and is not pressurizing the crankcase with boost.
4) be sure that you don't have a scratched cylinder wall - one bad cylinder can build more boost in the crankcase than you can possibly evacuate.
Both the face seal and the twin-lip seal require that the impeller shaft be flawless or the seal cannot seal against it. Sometimes I have to tell a customer that their
impeller shaft is so worn at the seal surface that they must get a new shaft from Vortech. It happens.
Here's a story: in a case where the supercharger was weeping oil, and we replaced the seals and the customer reported it was still weeping oil; we asked the customer to run this experiment. With the car on jack stands, he removed the drain hose from the nipple they had installed in the top of his oil pan. We had him attach a boost gauge to that nipple in the oil pan, and aim the supercharger drain hose at a bucket on the floor.
Then he ran the motor and revved the engine a few times. Not really a full-load test, but OK. He reported that the oil streamed out of the hose OK into the drain pan, but the crankcase pressure climbed into more than 2 psi just over 3000 rpm. Under load, this would be much higher. He learned that his crankcase was pressurizing and that his supercharger could drain, or would drain, if the crankcase would let it.
His search for a cause found him to a "vacuum line" from the PCV system (it was a vacuum line when the car was NA, now it's a pressurized line) that was still hooked up, and manifold pressure was being routed to the crankcase and pressurizing it. Shunting that line lowered the crankcase pressure, he gained HP, and the oil seals stopped weeping. (PS: just because you installed a "kit" dont assume the kit developer took this into account. You have to check. If you don't remember modifying the PCV system when you installed your supercharger, assume it hasn't been done.)
There is more on this topic, but that should give you a clearer picture as to what is going on.
If I can help, email me.
Carl Fausett
Member S.A.E.
928 Motorsports, LLC
There are two kinds: the face seal (which is what Vortech installs OEM) and a lip seal. Ours is a twin-lip seal.
As you know, they both fail. The OEM face seal leaks too after a time, and that's why you went looking for and found our twin-lip seal.
However: be sure that the seal is the real problem, and not just a symptom of a different problem.
Attach a boost pressure gauge to your crankcase temporarilly under load and see how much crankcase pressure you are building.
You might find the underlying cause for why your impeller shaft seals are weeping.
The Vortech supercharger (except the new V3 model) receives oil from the engine at about 60 to 80 psi while the engine is running.
Yet the drain is gravity only, and the oil in the supercharger is now entrained with air, making it even more sluggish and difficult to drain.
If the crankcase has pressure, the oil in the supercharger cannot drain, the supercharger case builds pressure, and the seals leak.
Some tips:
1) Be sure that your oil drain out of the supercharger is in the 6:00 (straight down) position
2) be sure that the oil drain is at least 3/4" in diameter. Nothing smaller.
3) be sure that the PCV system has been modified since the supercharger was installed, and is not pressurizing the crankcase with boost.
4) be sure that you don't have a scratched cylinder wall - one bad cylinder can build more boost in the crankcase than you can possibly evacuate.
Both the face seal and the twin-lip seal require that the impeller shaft be flawless or the seal cannot seal against it. Sometimes I have to tell a customer that their
impeller shaft is so worn at the seal surface that they must get a new shaft from Vortech. It happens.
Here's a story: in a case where the supercharger was weeping oil, and we replaced the seals and the customer reported it was still weeping oil; we asked the customer to run this experiment. With the car on jack stands, he removed the drain hose from the nipple they had installed in the top of his oil pan. We had him attach a boost gauge to that nipple in the oil pan, and aim the supercharger drain hose at a bucket on the floor.
Then he ran the motor and revved the engine a few times. Not really a full-load test, but OK. He reported that the oil streamed out of the hose OK into the drain pan, but the crankcase pressure climbed into more than 2 psi just over 3000 rpm. Under load, this would be much higher. He learned that his crankcase was pressurizing and that his supercharger could drain, or would drain, if the crankcase would let it.
His search for a cause found him to a "vacuum line" from the PCV system (it was a vacuum line when the car was NA, now it's a pressurized line) that was still hooked up, and manifold pressure was being routed to the crankcase and pressurizing it. Shunting that line lowered the crankcase pressure, he gained HP, and the oil seals stopped weeping. (PS: just because you installed a "kit" dont assume the kit developer took this into account. You have to check. If you don't remember modifying the PCV system when you installed your supercharger, assume it hasn't been done.)
There is more on this topic, but that should give you a clearer picture as to what is going on.
If I can help, email me.
Carl Fausett
Member S.A.E.
928 Motorsports, LLC
Banned
Joined: May 2002
Posts: 3,624
Likes: 11
From: Raleigh, NC
I have used waste gates on a number of different supercharger setups. It works exactly the same as it would on a turbo setup. It just blows off boost instead of exhaust gasses. Its a great way to make a ton of power when you can run race gas but still be able to drive the car every day. If you put the gate close to the blower it will help reduce parasitic losses as well.
Corkey Bell's book was good when it was written... 40 years ago
Corkey Bell's book was good when it was written... 40 years ago
Thread Starter
Joined: Nov 2005
Posts: 2,677
Likes: 9
99SH: your graph is interesting, but it does not show that the BLV is "not working". In order to do that, it needed one more pull with the BLV removed. Then you would see a dyno pull with the BLV removed and the BLV installed, and THEN we would see how much it did, or if it was working at all. I suspect as before that it is working, but not large enough to do the job at hand. The engine in the S2000 is pretty small, and the supercharger you are using at 1200 CFM is intended for a V8. I have no doubt it builds boost like crazy.
I did 3 runs with the BLV installed and can definitively say that it is not working for my application. Specifically, limiting boost to 12 PSI. The top green line was with the ball & spring completely removed. The two lines below are with the adjustment nut backed off all the way, and with it screwed in enough to preload the spring (just lightly). In all 3 cases, I was unable to limit boost to 12 PSI.
My plan is to mount it about 2" before the throttle body. Once I receive the Tial, this plan may change depending on how large it physically is. The other option would be on the heat exchanger next to the BOV flange (although space is very limited there as well)
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99SH: as we discussed in emails, I have no problem with saying that our BLV does not work in your application.
The only problem I had was the post that said the BLV "did not work". It does, but is way too small for your needs. It's a mis-application.
I will give you a free weld bung if you want so you can move it to another car or sell it to a friend. Just so your money was not wasted.
For the amount of CFM that you are trying to bleed off - the wastegate will do a much better job.
Carl
The only problem I had was the post that said the BLV "did not work". It does, but is way too small for your needs. It's a mis-application.
I will give you a free weld bung if you want so you can move it to another car or sell it to a friend. Just so your money was not wasted.
For the amount of CFM that you are trying to bleed off - the wastegate will do a much better job.
Carl
Joined: Oct 2002
Posts: 8,044
Likes: 6
From: South Florida
99SH: as we discussed in emails, I have no problem with saying that our BLV does not work in your application.
The only problem I had was the post that said the BLV "did not work". It does, but is way too small for your needs. It's a mis-application.
I will give you a free weld bung if you want so you can move it to another car or sell it to a friend. Just so your money was not wasted.
For the amount of CFM that you are trying to bleed off - the wastegate will do a much better job.
Carl
The only problem I had was the post that said the BLV "did not work". It does, but is way too small for your needs. It's a mis-application.
I will give you a free weld bung if you want so you can move it to another car or sell it to a friend. Just so your money was not wasted.
For the amount of CFM that you are trying to bleed off - the wastegate will do a much better job.
Carl
Ahhhh. This is good to know. So it's the blv not being big enough for this blower. Good info. Wastegate ftw.
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Joined: Jul 2012
Posts: 9
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[/quote]
Ahhhh. This is good to know. So it's the blv not being big enough for this blower. Good info. Wastegate ftw.
[/quote]
Almost. The BLV is not big enough for this application. Its not based on the blower. If his engine was larger, or less restricted, or that blower was installed on a different car, it might be just the ticket. We have many happy users of that item - but it does not have the range that he currently needs.
Ahhhh. This is good to know. So it's the blv not being big enough for this blower. Good info. Wastegate ftw.
[/quote]
Almost. The BLV is not big enough for this application. Its not based on the blower. If his engine was larger, or less restricted, or that blower was installed on a different car, it might be just the ticket. We have many happy users of that item - but it does not have the range that he currently needs.