Improve spool time on GT42?
you guys are missing the fact he has HUGE turbo. He should have at least a 14 psi spring in the gate. Thats well over 4000 rpms before the wastegate should even start to move (like 10psi). Of course the responses are academic, but not pertinent to this case.
Taking the lag outta a turbo that large isnt going to happen.
Taking the lag outta a turbo that large isnt going to happen.
you guys are missing the fact he has HUGE turbo. He should have at least a 14 psi spring in the gate. Thats well over 4000 rpms before the wastegate should even start to move (like 10psi). Of course the responses are academic, but not pertinent to this case.
Taking the lag outta a turbo that large isnt going to happen.
Taking the lag outta a turbo that large isnt going to happen.
ross
Well the examples I have mentioned in my case, its not a small turbo, its a HX40 with 18cm(equivalent to 1.00AR) turbine housing that comes from the dodge cummings truck, in addition my setup is rear mounted (I also have a 13psi spring), so I should know one or two things about lag and how to deal with it. To get back to ontopic, If you dont already have, I strongly suggest you wrap all your piping from headers to the turbo (not ceramic coat, unless you do ceramic coating PLUS wrap), the wrap is more effective. Thats the main reason I can get my rear turbo setup to spool up as quick as the front mount turbo setups(the wrap), also the SP quickspool valve will work too, I am in the process of making my own, but im taking my time with that.
Last edited by streetzlegend; Apr 28, 2010 at 02:28 PM.
What makes it work is that springs are not an on/off device. They are Linear in travel vs force.
see here:
http://en.wikipedia.org/wiki/Hooke%27s_law
the spring in the wastegate is designed to limit the maximum boost pressure and error on the safe side of limiting overboost. As the pressure increase inside the chamber the spring starts to compress and open the wastegate valve allowing the exhaust gas to bypass the turbine housing. The valve should be designed to be fully open at the desired PSI. If you cut the reference to o psi until the BC sees 10psi then you have eliminated this exhaust "leakage" and spooled the turbo quicker then if the spring started opening slightly at 8psi and full open at 10psi. The hard part is that you also have to fight overboosting.
Most BC's are PID based and will try to hit the target without overshoot and have a quick settling time. You can tune your BS for better results.
see here:
http://en.wikipedia.org/wiki/Hooke%27s_law
the spring in the wastegate is designed to limit the maximum boost pressure and error on the safe side of limiting overboost. As the pressure increase inside the chamber the spring starts to compress and open the wastegate valve allowing the exhaust gas to bypass the turbine housing. The valve should be designed to be fully open at the desired PSI. If you cut the reference to o psi until the BC sees 10psi then you have eliminated this exhaust "leakage" and spooled the turbo quicker then if the spring started opening slightly at 8psi and full open at 10psi. The hard part is that you also have to fight overboosting.
Most BC's are PID based and will try to hit the target without overshoot and have a quick settling time. You can tune your BS for better results.
EDIT: Never mind - I didn't take into consideration that the springs are heavily pre-loaded when they are installed into the wastegastes. How much pressure it takes to compress them a fraction of an inch is irrelevant. I think it would take quite a bit of pressure to get the wastegate to budge prematurely, especially with 1 bar springs.
Last edited by ttg35fort; Apr 29, 2010 at 08:30 PM.
Registered User
Joined: Feb 2010
Posts: 148
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From: Dekalb, IL
I'm not sure how I missed this one. Besides being on a Supra, this is exactly what you are looking for:
http://www.youtube.com/watch?v=I6ZCOTFET6s
This is the same car that Larry posted the dyno graph of.
Reid
http://www.youtube.com/watch?v=I6ZCOTFET6s
This is the same car that Larry posted the dyno graph of.
Reid
^^ ya but one important thing to note is that you need that $$$ valve AND a brand new divided scroll turbine housing plus the fabrication to make that fit.
Buy a dry shot of nitrous for 350$ and fill your bottle for the next 3 years for less money.
Buy a dry shot of nitrous for 350$ and fill your bottle for the next 3 years for less money.
I really wish SP would lower the price on these devices but monopoly on "quick spool valve" = overpricing the item lol
I gave up on making my own valve and just going to go with the dry shot.
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Joined: Jan 2007
Posts: 730
Likes: 1
From: Charlotte
I just looked at the Apexi website and I see they make that claim. I could find no data on their site to back it up, however. Here is their claim:
"The valve movement (Boost Duty Cycle) can also be modified. Raising the duty cycle increases boost response, while lowering the duty cycle will slow boost response. This feature allows boost response adjustment for varying turbo sizes. Since larger turbos take longer to spool up ( bad low end response) the duty cycle should be raised under lower RPM's for better response."
Essentially, their claim ignores the fact that all boost controllers (at least the ones I am aware of) keep the W/G closed until the desired boost level is reached. Hence, they don't even effect the turbo spoolup. During spoolup, the boost controller is generally irrelevant (assuming the boost controller is functioning properly). It only becomes relavent when the desired boost level is reached and they start to open the W/G, at which point the turbo is already spooled. So, no offence to you GBoger, but I am calling Apexi's claims as they I see them.
I haven't looked at the blitz controller, but I'll bet it's more of the same. EDIT: See Below - the Blitz controller does indeed perfrom well. I would take the Greddy Profec B over the A'pexi, though.
"The valve movement (Boost Duty Cycle) can also be modified. Raising the duty cycle increases boost response, while lowering the duty cycle will slow boost response. This feature allows boost response adjustment for varying turbo sizes. Since larger turbos take longer to spool up ( bad low end response) the duty cycle should be raised under lower RPM's for better response."
Essentially, their claim ignores the fact that all boost controllers (at least the ones I am aware of) keep the W/G closed until the desired boost level is reached. Hence, they don't even effect the turbo spoolup. During spoolup, the boost controller is generally irrelevant (assuming the boost controller is functioning properly). It only becomes relavent when the desired boost level is reached and they start to open the W/G, at which point the turbo is already spooled. So, no offence to you GBoger, but I am calling Apexi's claims as they I see them.
I haven't looked at the blitz controller, but I'll bet it's more of the same. EDIT: See Below - the Blitz controller does indeed perfrom well. I would take the Greddy Profec B over the A'pexi, though.
I'm speaking from personal experience with the apexi and many hours getting it dialed in vs. a Manual boost controller. I'm not saying that its = a quick spool valve or anything but I spooled at least 100-150 rpm sooner which can be quite significant.
I'm not seeing that in the test data I posted on the previous page of this thread, however. Perhaps the guys who generated the test data did not spend as much time tweaking with it. I don't know.
Last edited by ttg35fort; Jun 6, 2010 at 07:31 PM.
That quick spool valve is impressive. If it can work magic on a big turbo like that, which costs several thousand dollars in and of itself, I'd say the additional $500 is worth it. Of course, there is the fabrication to make it fit...
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