Greddy T620z

[Eazy-V]

I think I found the reason for the confusion. Seems like Greddy USA is stating 15-20psi, but Trust Japan has that wastegate listed correct at 12psi.

[Xero-Limit]

Originally Posted by Eazy-V

I think I found the reason for the confusion. Seems like Greddy USA is stating 15-20psi, but Trust Japan has that wastegate listed correct at 12psi.

Looking back at datalogs we saw 10 psi. 3" exhaust will make more boost.

Originally Posted by stevo585

I would think more like mid 400's on e85. Can't the T518z hit nearly 400whp? Maybe I'm getting this confused with the SBD kit.

400 even on e85 is not easy. We see the SBD bigger turbo kit (20g iirc) top out in the 380s at 14-15 psi on a stock motor. A t3 framed turbo is more likely to hit mid 400's, though we have seen it with the gtx2867r on a very optimized JDL setup.

I would have no qualms going t620z on the stock motor, unless running 91 exclusively and doing track time.

[fz6r]

Originally Posted by moto-mike

Looking back at datalogs we saw 10 psi. 3" exhaust will make more boost.



400 even on e85 is not easy. We see the SBD bigger turbo kit (20g iirc) top out in the 380s at 14-15 psi on a stock motor. A t3 framed turbo is more likely to hit mid 400's, though we have seen it with the gtx2867r on a very optimized JDL setup.

I would have no qualms going t620z on the stock motor, unless running 91 exclusively and doing track time.

So with the 620z, hitting over 400 would be difficult? My low boost set up is 12psi just running off the waste gate. I do have a 3in exhaust.

My high boost set up is 16.3psi. I'm also on e85 (and only using high boost while on e85)

[Crazypinoy9]

Originally Posted by fz6r

No. It's just the turbo and piping. I bought injectors, map sensor, and fuel pump separate. The stock wastegate with the 620z is 12lbs. with the 518z you'd be at 7-8lbs. If you want to stay under 12lbs... go with the 518 over the 620.

Or...because of the price point, just go with the 620 and use an EBC to keep the boost down a little. that way he has the headroom to go higher if he wants to in the future. The price delta between the 518 and the 620 is so minimal that it makes more sense. At least to me it does but then again my logic sometimes is outta wack

[armstrom]

Originally Posted by Crazypinoy9

...just go with the 620 and use an EBC to keep the boost down a little. that way he has the headroom to go higher if he wants to in the future.

Just a point of clarification, a boost controller cannot "keep boost down". If the turbo makes 13psi on the wastegate alone the boost controller can only raise boost from there. The trick is to get a wastegate configured for the lowest pressure you want to run, then if you want to increase boost later you can slap on a boost controller.
-Matt

[Jaden]

Originally Posted by fz6r

No. It's just the turbo and piping. I bought injectors, map sensor, and fuel pump separate. The stock wastegate with the 620z is 12lbs. with the 518z you'd be at 7-8lbs. If you want to stay under 12lbs... go with the 518 over the 620.

The 620 is going to be flowing more air at 7-8 than the 518, let alone 12...


Jaden

[Crazypinoy9]

Originally Posted by armstrom

Just a point of clarification, a boost controller cannot "keep boost down". If the turbo makes 13psi on the wastegate alone the boost controller can only raise boost from there. The trick is to get a wastegate configured for the lowest pressure you want to run, then if you want to increase boost later you can slap on a boost controller.
-Matt

really? cuz right now i've got a 12psi wastegate after I had my turbo upgraded and because of crappy fuel im temporarily at 10psi via my EBC and tune. I'm not challenging you, but is there maybe something wrong with MY setup then? Something i'm not accounting for?

[armstrom]

Originally Posted by Crazypinoy9

really? cuz right now i've got a 12psi wastegate after I had my turbo upgraded and because of crappy fuel im temporarily at 10psi via my EBC and tune. I'm not challenging you, but is there maybe something wrong with MY setup then? Something i'm not accounting for?

Yes, the wastegate pressure determines the minimum pressure you can hold.

The reasons may not be quite so obvious, and there are several factors that could cause a "12 PSI wastegate actuator" to actually only deliver 10PSI.

First, you have to picture the forces going on here. If you have a simple internal wastegate actuator with a single port You basically have a diaphragm that the boost pressure can act against, on the other side of the diaphragm is a spring that gets compressed as the boost pushes the diaphragm down and a rod that moves with the diaphragm and opens the wastegate itself. So Boost Pressure->Pushes on Diaphragm->Compresses spring->Opens wastegate.

With a boost controller in there you're basically intercepting the boost pressure input to the actuator and either blocking it entirely or bleeding some of it off (different boost controllers work slightly differently). This allows you to make, say, 20PSI on a 10PSI wastegate. The EBC simply blocks/bleeds the boost reference until it approaches 20PSI, then it lets it all through. Since 20PSI is more than enough to compress the spring in your 10PSI actuator, it opens reducing turbine speed and therefore holding boost at 20PSI.

However, boost pressure isn't the only pressure acting on the spring. It also has to hold the wastegate closed against the exhaust backpressure in the manifold. This backpressure is always trying to force the wastegate open and only the spring is able to keep it shut.

This is why some cars that are able to hold a steady 10PSI (or whatever) of boost suddenly see boost creeping up to 12-13PSI when they install a free flowing exhaust manifold, exhaust system, big cams, whatever. There's now less exhaust backpressure trying to open the wastegate so it takes more boost to do it. This is also why simple 1-port wastegate actuators don't work well when trying to run really high boost on a light spring. If your wastegate actuator spring is meant to run 10PSI and you install a boost controller and try to make 30 PSI (don't do this, BTW ) then it will likely fail to hit that boost since the exhaust backpressure alone is enough to open the gate. This is why dual-port wastegates/actuators exist.. but that's an entirely different discussion.

Another reason a turbo might only make 10PSI on a 12PSI actuator is that the engine might be out-flowing the turbo. This is not what is happening to you as it normally only happens when using too small of a turbo for the power goals. You can go down a huge rabbit hole of discussing compressor and turbine flow maps, surge lines, etc... but suffice it to say, your actuator is probably just going to make 10PSI on your car and everything is just fine. Upgrade your exhaust

-Matt

[Crazypinoy9]

Originally Posted by armstrom

Yes, the wastegate pressure determines the minimum pressure you can hold.

The reasons may not be quite so obvious, and there are several factors that could cause a "12 PSI wastegate actuator" to actually only deliver 10PSI.

First, you have to picture the forces going on here. If you have a simple internal wastegate actuator with a single port You basically have a diaphragm that the boost pressure can act against, on the other side of the diaphragm is a spring that gets compressed as the boost pushes the diaphragm down and a rod that moves with the diaphragm and opens the wastegate itself. So Boost Pressure->Pushes on Diaphragm->Compresses spring->Opens wastegate.

With a boost controller in there you're basically intercepting the boost pressure input to the actuator and either blocking it entirely or bleeding some of it off (different boost controllers work slightly differently). This allows you to make, say, 20PSI on a 10PSI wastegate. The EBC simply blocks/bleeds the boost reference until it approaches 20PSI, then it lets it all through. Since 20PSI is more than enough to compress the spring in your 10PSI actuator, it opens reducing turbine speed and therefore holding boost at 20PSI.

However, boost pressure isn't the only pressure acting on the spring. It also has to hold the wastegate closed against the exhaust backpressure in the manifold. This backpressure is always trying to force the wastegate open and only the spring is able to keep it shut.

This is why some cars that are able to hold a steady 10PSI (or whatever) of boost suddenly see boost creeping up to 12-13PSI when they install a free flowing exhaust manifold, exhaust system, big cams, whatever. There's now less exhaust backpressure trying to open the wastegate so it takes more boost to do it. This is also why simple 1-port wastegate actuators don't work well when trying to run really high boost on a light spring. If your wastegate actuator spring is meant to run 10PSI and you install a boost controller and try to make 30 PSI (don't do this, BTW ) then it will likely fail to hit that boost since the exhaust backpressure alone is enough to open the gate. This is why dual-port wastegates/actuators exist.. but that's an entirely different discussion.

Another reason a turbo might only make 10PSI on a 12PSI actuator is that the engine might be out-flowing the turbo. This is not what is happening to you as it normally only happens when using too small of a turbo for the power goals. You can go down a huge rabbit hole of discussing compressor and turbine flow maps, surge lines, etc... but suffice it to say, your actuator is probably just going to make 10PSI on your car and everything is just fine. Upgrade your exhaust

-Matt

I appreciate your explanation, but I'm not saying I'm not able to run 12psi. Because I WAS running it fine by switching my map since I have 3 (10psi 91oct, 12psi 93oct, 12psi 100oct)
I had my tuner set me up for a 10psi map as my primary for now to play it safe because Socal 91 oct sucks balls. I originally started out with a 7psi wastegate when i got the turbo kit. i ditched it about 3 months ago when the rod snapped

[Eazy-V]

Originally Posted by Crazypinoy9

I appreciate your explanation, but I'm not saying I'm not able to run 12psi. Because I WAS running it fine by switching my map since I have 3 (10psi 91oct, 12psi 93oct, 12psi 100oct)
I had my tuner set me up for a 10psi map as my primary for now to play it safe because Socal 91 oct sucks balls. I originally started out with a 7psi wastegate when i got the turbo kit. i ditched it about 3 months ago when the rod snapped

Is there a lower psi wastegate that I can put on a T620z?

I want to run it at 10psi max with stock engine/fuel (stock wastegate is listed at 12psi) until at least next year, then might build the engine.

[Fizz]

This place sells just the actuator head which allows you to pop in whatever psi spring you select, then re-use your existing actuator rod and bracket. They've got a 7psi one so that could be your lowest boost setting, then you can run it at a higher boost using either an mbc or ebc

http://shopping.kinugawaturbo.com/ki...uatorhead.aspx

[ZeroTo86]

Originally Posted by Fizz

This place sells just the actuator head which allows you to pop in whatever psi spring you select, then re-use your existing actuator rod and bracket. They've got a 7psi one so that could be your lowest boost setting, then you can run it at a higher boost using either an mbc or ebc



http://shopping.kinugawaturbo.com/ki...uatorhead.aspx

Did you use this on your own build? It works with the Greddy kit?

[Fizz]

Originally Posted by ZeroTo86

Did you use this on your own build? It works with the Greddy kit?

No I didn't.....but it should work. Check the dimensions of your current wg and compare with the kinugawa one. If they're similar it should bolt right up with your existing actuator bracket.