Hello All,

I have an EF4 with the turbosmart IWG, spool has always been lazy since install, I aim to improve spool. On a previous log I am seeing 20 psi by 4600 rpm, this seems quite a bit late. My question is to the EF turbo guys, does anyone know whether the actuator arm is preload from MAP at all or is it at zero preload? Also, does anyone know what spring is inside the actuator? Thanks

 

There are a couple different spring rate options available on that MAP/Turbosmart actuator. Do you know which spring is inside your actuator? You may want to call MAP and order the stiffest spring from MAP. You probably will want the stiffest 24-26# spring for running the boist levels that the EF4 is capable of.

 

Yes, however I would check to see that the WGA is actually set correctly first.

sparky's thread on here show how to do that correctly, just search on those.

 

I would aim for 20# by 3800-4000 RPM with that turbo. Maybe it is not quite doable, but I would not settle for anything later than 4200 RPM for that boost level.

Tell us how you are controlling boost on your setup?

 

Regardless of what spring is in the actuator and regardless of at what level of spring pressure MAP tests and ships the turbos, as a practical mater you can easily verify what actual wastegate spring pressure is on your setup. Once we establish actual spring pressure then we can proceed from there to increase the WG spring pressure(preload). We want to get that big puppy spooling up quicker for you.

 

IIRC, the WG spring on my EF3 was either a 15lb or 18lb spring from MAPerformance. I'm leaning towards it being the 18lb spring.

And yes, mine was already preloaded from MAP. I think we were only able to tighten it a little more.

 

Sparky, I am using a gm 3 port.

 

Agreed, I am seeing 20 psi noooooowhere near 3900-4100 rpm in 3rd gear. I will pull the actuator off to confirm what spring is inside, I will also confirm that any preload on the arm itself. Thanks for the help sparky.

 

Got the actuator off, rod has zero preload, slides off and on with no lateral effort. I am currently trying to get the WG apart, this design is retarded with a top locking ring. Should be designed like a Tial WG.....

 

What is your desired peak boost level?

 

Peak boost is 30 psi.

 

For a peak boost level of 30#, you will want to run at least 24-25# spring pressure minimum. Ideally, you could shoot for a spring pressure of 26-27#. Depends on which spring is in there, but 24# should be doable even with their weakest spring.

 

thought so..Get the WGA adjusted correctly first. Sparky is the man for that

 

Can I just be the first to say this actuator design is terrible, the "coilover" style locking top ring has stripped written all over considering I only took it off once and the design is already wearing. Not only that but this actuator is apparently not water resistant at all, the entire thing was full of water and rust, the springs are rusted beyond identification. By best guess it looks like a 10# outer spring and a 7# middle spring making 17# total. I think by stepping up to a heavier internal spring and preloading the arm itself I bet we can get this ef4 spooling a lot faster. What do you think Sparky?

 

I went with a 21# wg spring and did three half turns of preload on the wg arm, all I can say is wow. The car is night and day different, part throttle boost comes on way quicker, the car feel peppier. The best news is I now make 20 psi by 4306 rpm with nothing done to the tune!!! With additional spool area tuning I can see hitting 20 psi by 4100 rpm, 30 psi should be right around 4400-4500 rpm. A word of caution to anyone attempting this, turn your boost down atleast 5-7 psi, the preload and wg spring affect my peak boost by +5 psi. If you have a lazy spooling stock frame turbo this is your solution!