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Old 02-07-2013, 09:17 AM   #1
JMlegacy
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Default AVO Solid Boost Actuator

Good night friends,

So i've looked on my graphs and realize that the boost drops after 5 or 6k RPM and so does my torque and HP curve. I've been under the impression that this is a result of turbo efficiency. Now I learn that it's the spring in the wastegate actuator that does this.

I was wondering if using avo 15psi Solid Boost Actuator Actuator will make a noticeable difference. I'm bearing in mind that at redline the air at the increased boost will be poorer quality than what was there before. How much worse, idk. I'm hoping there wont be much compromise in air quality (IAT). I'm aiming for 17psi tapering to 15 @ redline

Here is my dyno chart so far. At the bottom is the boost and AFR.

specs:
JDM 2.0 twinscroll vf38 (vf40 equiv)
De-catted downpipe
91 gas





and THIS is my expectation in HP and TQ. Is this a reasonable expectation?

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Last edited by JMlegacy; 02-07-2013 at 09:39 AM.
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Old 02-07-2013, 09:34 AM   #2
kpluiten
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I can't speak to your expectations because I don't know what turbo you're running, but check out the Kinugawa/Kamak adjustable waste gate actuators. They are cheaper than the AVO unit and perform well by all accounts. There is a wide variety of springs for them as well.

I also think that turbo efficiency will still impact you on the top end even with the actuator upgraded if we're talking the VF37/36 on an EJ207. But you'll certainly see an improvement.
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Old 02-07-2013, 09:39 AM   #3
JMlegacy
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VF38 on legacy GT
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Old 02-07-2013, 09:43 AM   #4
Vlad
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Does the avo have a functional lower boost chamber? Then paired with a 3 port solenoid and piped like the 2-pipe EWG actuator connection, it may beat the Kinugawa.
But, like kpluiten mentioned, you can't go around the VF efficiency level with an actuator.
Also, VF36/37 are said to last around 60 K miles, when they have a "tough life", as in upgraded actuator.
Edit: VF38 is even smaller, on the compressor side, I think.
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Old 02-07-2013, 09:44 AM   #5
quazimoto
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Are you still using the stock 2-port boost control solenoid?
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Old 02-07-2013, 11:04 AM   #6
JMlegacy
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Quote:
Originally Posted by Vlad View Post
Does the avo have a functional lower boost chamber? Then paired with a 3 port solenoid and piped like the 2-pipe EWG actuator connection, it may beat the Kinugawa...
I have no idea what you talking about, excuse my ignorance

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Originally Posted by quazimoto View Post
Are you still using the stock 2-port boost control solenoid?
Yes, stock boost control solenoid.
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Old 02-07-2013, 12:06 PM   #7
Vlad
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They have two chambers, from outside there are two connectors. A normal one only has one.
The EWG actuators have two.
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Old 02-07-2013, 12:08 PM   #8
JMlegacy
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Quote:
Originally Posted by Vlad View Post
They have two chambers, from outside there are two connectors. A normal one only has one.
The EWG actuators have two.
Oh, I think with the AVO it's just a stiffer spring in the actuator
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Old 02-07-2013, 06:10 PM   #9
simon021
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Your HP curve on that graph is not a reasonable expectation of that turbo. The torque is a bit more reasonable. If you do a google search for dyno graphs with your same setup, you will see the same thing. The turbo is not efficient up in that range, so the boost must be tapered off. If you want to increase power all the way to redline, you will need a bigger turbo.

thats not to say theres not room for improvement with your setup. A 3 port boost controller would make a noticeable improvement in spool and probably hold more boost up top as well.
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Old 02-07-2013, 06:21 PM   #10
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If you are on a completely stock tune, then there is likely a significant amount of taper built into the factory tune. Based on your fueling it looks like you're not on the factory tune, though.

I have no idea how much a vf38 flows, but you could also be near it's terminal flow, in which case the curve looks fairly normal, but I'd expect a turbo of that flow capability would spool MUCH sooner than it is (somewhere under 3000 RPM.) However, you're in 2nd gear for that pull (this is what it says in the graph?) I'd use a higher gear, whatever gear is close to 1:1 (5MT this is usually 3rd. 6MT is usually 4th at a ratio of something like 0.97)

Last edited by Concillian; 02-07-2013 at 06:26 PM.
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Old 02-07-2013, 08:26 PM   #11
JMlegacy
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Quote:
Originally Posted by simon021 View Post
Your HP curve on that graph is not a reasonable expectation of that turbo. The torque is a bit more reasonable. If you do a google search for dyno graphs with your same setup, you will see the same thing. The turbo is not efficient up in that range, so the boost must be tapered off. If you want to increase power all the way to redline, you will need a bigger turbo.

thats not to say theres not room for improvement with your setup. A 3 port boost controller would make a noticeable improvement in spool and probably hold more boost up top as well.
OK

Quote:
Originally Posted by Concillian View Post
If you are on a completely stock tune, then there is likely a significant amount of taper built into the factory tune. Based on your fueling it looks like you're not on the factory tune, though.

I have no idea how much a vf38 flows, but you could also be near it's terminal flow, in which case the curve looks fairly normal, but I'd expect a turbo of that flow capability would spool MUCH sooner than it is (somewhere under 3000 RPM.) However, you're in 2nd gear for that pull (this is what it says in the graph?) I'd use a higher gear, whatever gear is close to 1:1 (5MT this is usually 3rd. 6MT is usually 4th at a ratio of something like 0.97)
Yes, I was in 2nd gear. Hardly any road for 3rd gear pull unless I go on the highway. But I do notice something weird with my car. Sometimes in 3rd gear it has basically no boost, esp when climing from about 3K rpm to redline....hardly ever pulls. If I go from 2nd to 3rd it is sometimes much better, or if I keep it in high rev in 3rd (4k+). The most exciting gear for this car at this stage is 2nd gear. 3rd gear feels like a regular car. I want something better.

I've been doing research into turbo upgrades for 280WHP daily driver. Found that the Kinugawa 16G might work but I need headers, up and downpipe for that conversion...and injectors
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Old 02-07-2013, 11:06 PM   #12
buddy110
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I'm suffering from the same issue with my built motor. Only I have a 3076.82 running with a cosworth FMIC, cams, heads, and ALL the goodies. My boost tapers at 5700 and HP follows it. My tuner/builder thinks it might be the EWG up-pipe. We have a 20lb spring in the ewg now, which helped spool, but the taper remained unchanged. Totally stumped
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Old 02-07-2013, 11:27 PM   #13
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After some googling for vf38, it does appear to be pretty small, on the order of TD04 sized, perhaps even smaller...

It also has a different housing from the STi twinscroll, so a larger turbo would require a complete exhaust change from heads to catback. Ouch.

So what you're getting is more or less the expected result from a 2nd gear pull. A turbo that small will not see benefit from a heavier actuator. There may be benefits to trying to crack open the WG a little at high RPM just to relieve some of the backpressure and lower EGTs. I know on my TD04, I could tune in a fair amount of duty cycle before dropping power / boost.
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Old 02-08-2013, 08:32 AM   #14
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Quote:
Originally Posted by Concillian View Post
It also has a different housing from the STi twinscroll, so a larger turbo would require a complete exhaust change from heads to catback.
+1 .....
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