HedgeyGedgey

Hi all, question about actuators. What affect on drivability would there be if say you put a 20psi spring in the actuautor? and if nothing why doesn't everyone just put the strongest spring that their engine can handle boost wise?

llDemonll

iTrader: (21)

when it releases under partial throttle it'll be too stiff and the valve will flutter

deylag

iTrader: (23)

What turbo are you going to use and what is your target boost pressure?

You don't need the strongest stiffest spring in every application. A closed wastegate makes the engine see more boost than it can handle. It's better to balance it out with a spring that can hold the boost pressure at the target and give good throttle response.

4b11slayer

Im assuming your speaking of the wastegate and not a Blow off valve.


If you use a 20 psi spring along with a boost controller you can see 30 psi.

If you put a 30 psi spring you will see a minimum of 30 psi in case of a controller plumping failure.

HedgeyGedgey

Thanks chaps, so running a tomei arms turbo so all internally gated. It's got a forge actuator on it with I think a 1.2bar spring. Will be looking to run no more than 2 bar

HedgeyGedgey

Bit more time to post a reply, we're investigating a boost issue basically, not holding anything more than 1.6bar and tailing off a lot through the revs, changed the cams to 272's but haven't had a chance to do some proper logs. The actuator tension wasn't set up correctly when it was put on 2 years ago, but it was holding 1.5ish bar before the engine was forged. As soon as the bottom end was rebuilt, 264inlet and 256exhaust cams put in it was dropping boost off so couldn't finish mapping. Was wondering if the actuator was at fault, and the question above was also curiously lol

240Z TwinTurbo

iTrader: (25)

For an internal gated application, a lighter spring has the potential to open the puck at lower boost pressures. This is due to EMAP pressure on the puck face, which is typically at least 1.5x boost pressure. This gradual opening of the puck at lower boost pressures can cause lag, but won't affect "drivability." Same principle applies to external gate except you have a valve instead of a puck.

I run ~25psi springs in my twin 38mm Tials because I don't run under 30psi and that was the strongest spring you could buy. I would advocate for something a few psi lower than what you expect to run as a minimum boost pressure.