2 port wastegate and wastegate creep

[jabbatron]

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[JustenGT8]

The diagram is correct, well that's one correct way to do it anyways.

You'll just have to try it to see how well it works. These systems can be sensitive to the relative length of lines and the size of the WG valve, as well as how the WG angle is set up on the exhaust manifold.

[Cuts]

^^what he said^^

Ide like to add that if your going to be running 18 psi get a higher pressure wastegate spring, you should have your wastegate spring pressure as close to your target boost pressure as possible. So my advice, get a 1 bar spring.

[thechuckster]

Maybe i'm looking at it wrong, but once the solenoid opens up you don't have boost-referenced waste-gate control as - as jabbatron point out - the pressure on either side of the diaphragm is equalised. Once the solenoid opens up to 100%, the only thing holding the valve shut is the spring.

If you wanted to ensure the system was keeping the gate closed and modulating that control with the solenoid, have it close off the lower boost-reference feed to the wastegate before exhaust manifold pressure can overcome the spring?

fwiw: From memory, folks doing PWM boost control with megasquirt were using a PWM solenoid and using a light spring - thus at 0% duty, the boost was limited to the spring rating, whereas at 100% duty, the boost was lifted to spring plus 100% MAP. I guess boost control is different to wastegate-creep control (one is about opening the gate up whenever you want, the other is about keeping it shut).

[wilbo666]

Turbosmart have some nice drawings / info in their manuals.

I.e. page 6 in the following link (eBoost 2 manual)
http://www.turbosmartonline.com/inde...ownload&id=350

Cheers
Wilbo

[jabbatron]

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[JustenGT8]

I had assume Chuckster that the solenoid bleeds to atm? looks like it does? and you'd have a reducer at the T? In which case the layout would work.

[jabbatron]

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[JustenGT8]

The solenoid is controlling top of the diaphram. With the solenoid inactive you have restricted a boost signal to the bottom port (should be a restrictor there?) so WG is held shut. As you reach the boost level you want the solenoid bleeds to atm and proportionally the feed to the lower port increases, therefore opening the valve and controlling boost to the set level.

[jabbatron]

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[JustenGT8]

Ok that's weird every EBC i've seen uses a 3 port solenoid and the dia looks like it bleeds out the top? In that case Chuck is on the money.

If it did bleed to atm it wouldn't equalise as there's a preferential flow path...as i said, that's how most of the EBCs on the market work.

[thechuckster]

I was just following the arrow directions in the diagram (which didn't suggest a 3rd port in the solenoid). Struck me as very weird that there was no 3rd port/path.

To be honest, my experiences with boost regulation was pinching Wilbo's ghetto-spec boost controller and seeing how much boost we could extract from the 18RTE.

[jabbatron]

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[mattysshop]

thread dig -

would it matter is an EBC solenoid has been connected from compressor housing - EBC solenoid - bottom/side port of the external gate (38mm tial)... top port just venting to atmo... not connected like this...

http://www.tialmedia.com/documents/w..._wginstall.pdf