Dyno Results - Ball and Spring MBC
02-24-2012, 09:50 PM
#1
Rennlist Member
Thread Starter
Dyno Results - Ball and Spring MBC
Been experimenting with boost control to see if I could hold boost a bit better at high rpm's and flatten out my torque curve. Tried a setup Rogue suggested a while back as shown here:
Results were interesting. The Mods are M Tune, Tial 38, TO4E DBB 50 Trim #8 hotside, and Bursch Test Pipe. The run below was with E85 at 18psi.
It helped slightly to flatten things out on the high end but I was surprised that it made a such a significant improvement in mid-range torque (about 25 ft-lb increase between 3500-5000). Having trouble getting my mind wrapped around why.
I am still trying to understand my boost curve. If peak boost is 18 psi, boost falls to about 16.5 psi at redline. I was thinking this is a flow limit issue but if I reduce peak boost to 15 psi, boost still falls to about 13.5 psi at redline. Any input is appreciated.
Results were interesting. The Mods are M Tune, Tial 38, TO4E DBB 50 Trim #8 hotside, and Bursch Test Pipe. The run below was with E85 at 18psi.
It helped slightly to flatten things out on the high end but I was surprised that it made a such a significant improvement in mid-range torque (about 25 ft-lb increase between 3500-5000). Having trouble getting my mind wrapped around why.
I am still trying to understand my boost curve. If peak boost is 18 psi, boost falls to about 16.5 psi at redline. I was thinking this is a flow limit issue but if I reduce peak boost to 15 psi, boost still falls to about 13.5 psi at redline. Any input is appreciated.
02-24-2012, 09:59 PM
#2
Rennlist Member
very nice sir... I always enjoy reading your dyno's and experiments 
Since it's not holding I would imagine either Wastegate or MBC, but since your Wastegate is a new Tial I would wonder maybe the mbc... Were the MBC's like cheap 20 dollar ones or from a good company? Maybe a EBC would be better? Or Tial wastegate spring limitations?
Since it's not holding I would imagine either Wastegate or MBC, but since your Wastegate is a new Tial I would wonder maybe the mbc... Were the MBC's like cheap 20 dollar ones or from a good company? Maybe a EBC would be better? Or Tial wastegate spring limitations?
02-24-2012, 10:30 PM
#4
Race Car
MBC's usually overshoot and then settle to the desired pressure. EBC's are different in the fact they are trying to target a pressure within the unit and use a solenoid to control pressure to the wg. Without the solenoid the MBC is relying on just limiting pressure against the wg spring pressure.
Then you can also factor in using different springs in the wg to get different control areas. I like having a heavy spring and using the controller to be able to run a little less pressure or a lot more.
Then you can also factor in using different springs in the wg to get different control areas. I like having a heavy spring and using the controller to be able to run a little less pressure or a lot more.
02-24-2012, 10:33 PM
#5
Race Car
I'd also shift that thing at 6000rpm. How are the knock counts up high? If your not seeing many up there you may be able to add a little timing and hold tq a bit longer yet.
02-24-2012, 10:35 PM
#6
Totally just theorizing here and talking out of my butt:
I think it just has to do with the fixed amount of pressure you're sending the WG. Maybe it's something like once the WG has been cracked off it's seat, the exhaust flow keeps it open? I've kinda noticed the same thing with my MBC as you. If I hit 15psi peak, it falls off to 13 later. If I dial it back and hit ~13psi peak, it falls off to 11 later. If I remember correctly, when I had NO boost controller in the loop (just straight lines to the WG) it peaked at 11psi - but *still* fell back a bit by redline (to maybe 9-10.) The fact that it held 13psi longer at one point tells me that it's capable, but something else is holding it back. This is all on a freshly rebuilt 26/6, Lindsey MBC, and Tial 38 WG.
An EBC with programmable curve, methinks, would "solve" it by adjusting the duty cycle later in the rpm band to push more boost. A way to test this idea would be to have someone sit there with the MBC in their hand as you drive, and as you rev it higher, have them adjust the MBC to see if you can fake a "flat" boost curve.
I've had some of my own ideas to build my own EBC, and have also talked to at least one good vendor who is working on their own solution (which I would rather use, IMO.) But the logic for it, at least in my head, if I had to build my own, is pretty simple.
I think it just has to do with the fixed amount of pressure you're sending the WG. Maybe it's something like once the WG has been cracked off it's seat, the exhaust flow keeps it open? I've kinda noticed the same thing with my MBC as you. If I hit 15psi peak, it falls off to 13 later. If I dial it back and hit ~13psi peak, it falls off to 11 later. If I remember correctly, when I had NO boost controller in the loop (just straight lines to the WG) it peaked at 11psi - but *still* fell back a bit by redline (to maybe 9-10.) The fact that it held 13psi longer at one point tells me that it's capable, but something else is holding it back. This is all on a freshly rebuilt 26/6, Lindsey MBC, and Tial 38 WG.
An EBC with programmable curve, methinks, would "solve" it by adjusting the duty cycle later in the rpm band to push more boost. A way to test this idea would be to have someone sit there with the MBC in their hand as you drive, and as you rev it higher, have them adjust the MBC to see if you can fake a "flat" boost curve.
I've had some of my own ideas to build my own EBC, and have also talked to at least one good vendor who is working on their own solution (which I would rather use, IMO.) But the logic for it, at least in my head, if I had to build my own, is pretty simple.
02-24-2012, 10:42 PM
#7
Rennlist Member
Thread Starter
very nice sir... I always enjoy reading your dyno's and experiments
Since it's not holding I would imagine either Wastegate or MBC, but since your Wastegate is a new Tial I would wonder maybe the mbc... Were the MBC's like cheap 20 dollar ones or from a good company? Maybe a EBC would be better? Or Tial wastegate spring limitations?
Since it's not holding I would imagine either Wastegate or MBC, but since your Wastegate is a new Tial I would wonder maybe the mbc... Were the MBC's like cheap 20 dollar ones or from a good company? Maybe a EBC would be better? Or Tial wastegate spring limitations?
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02-24-2012, 10:44 PM
#8
Rennlist Member
Thread Starter
MBC's usually overshoot and then settle to the desired pressure. EBC's are different in the fact they are trying to target a pressure within the unit and use a solenoid to control pressure to the wg. Without the solenoid the MBC is relying on just limiting pressure against the wg spring pressure.
Then you can also factor in using different springs in the wg to get different control areas. I like having a heavy spring and using the controller to be able to run a little less pressure or a lot more.
Then you can also factor in using different springs in the wg to get different control areas. I like having a heavy spring and using the controller to be able to run a little less pressure or a lot more.
02-24-2012, 10:49 PM
#10
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02-24-2012, 11:28 PM
#11
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Nice hp & tq(!) pickup 
Especially for nothing besides changing the boost control setup.
Lol - Sid is like that little guy on my shoulder telling me to add boost/timing.
I think the next logical step is simply an EBC to actually hold boost - that alone will pickup another ~15hp or so.
Especially for nothing besides changing the boost control setup.
I think the next logical step is simply an EBC to actually hold boost - that alone will pickup another ~15hp or so.
02-24-2012, 11:37 PM
#12
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Thread Starter
hahah
02-24-2012, 11:57 PM
#14
Rennlist Member
Thread Starter
Totally just theorizing here and talking out of my butt:
I think it just has to do with the fixed amount of pressure you're sending the WG. Maybe it's something like once the WG has been cracked off it's seat, the exhaust flow keeps it open? I've kinda noticed the same thing with my MBC as you. If I hit 15psi peak, it falls off to 13 later. If I dial it back and hit ~13psi peak, it falls off to 11 later. If I remember correctly, when I had NO boost controller in the loop (just straight lines to the WG) it peaked at 11psi - but *still* fell back a bit by redline (to maybe 9-10.) The fact that it held 13psi longer at one point tells me that it's capable, but something else is holding it back. This is all on a freshly rebuilt 26/6, Lindsey MBC, and Tial 38 WG.
An EBC with programmable curve, methinks, would "solve" it by adjusting the duty cycle later in the rpm band to push more boost. A way to test this idea would be to have someone sit there with the MBC in their hand as you drive, and as you rev it higher, have them adjust the MBC to see if you can fake a "flat" boost curve.
I've had some of my own ideas to build my own EBC, and have also talked to at least one good vendor who is working on their own solution (which I would rather use, IMO.) But the logic for it, at least in my head, if I had to build my own, is pretty simple.
I think it just has to do with the fixed amount of pressure you're sending the WG. Maybe it's something like once the WG has been cracked off it's seat, the exhaust flow keeps it open? I've kinda noticed the same thing with my MBC as you. If I hit 15psi peak, it falls off to 13 later. If I dial it back and hit ~13psi peak, it falls off to 11 later. If I remember correctly, when I had NO boost controller in the loop (just straight lines to the WG) it peaked at 11psi - but *still* fell back a bit by redline (to maybe 9-10.) The fact that it held 13psi longer at one point tells me that it's capable, but something else is holding it back. This is all on a freshly rebuilt 26/6, Lindsey MBC, and Tial 38 WG.
An EBC with programmable curve, methinks, would "solve" it by adjusting the duty cycle later in the rpm band to push more boost. A way to test this idea would be to have someone sit there with the MBC in their hand as you drive, and as you rev it higher, have them adjust the MBC to see if you can fake a "flat" boost curve.
I've had some of my own ideas to build my own EBC, and have also talked to at least one good vendor who is working on their own solution (which I would rather use, IMO.) But the logic for it, at least in my head, if I had to build my own, is pretty simple.
Also, love the new avatar. Great pic!
then get a 4" exhaust as well, ring and port the head and install larger valves