Just Dynoed Rb20det

[Waldo]

hey guys just got my rb20 tuned and finished today, its didnt pull the power i wanted but i think this is due to lack of boost, i have high flowed turbs and all the supporting mods to run over 320rwhp, but when they went to tune it at 18psi, it would spike there then drop straight back to 12psi, wat is the deal there, there is no leaks in the cooler pipin anywhere as they thoroughly went over them, could this be the actuator on the turbo giving in, or would it be the stock bov opening up? how to i test these 2 things, any recommendations on wat it is would be greatly appreciated. So atm its tuned on 12psi.

[Cubes]

A good closed loop EBC is needed.

An EBC that is able to change duty cycle on the fly to obtain the boost pressure you require.

There's a few that do this, the well known ones being the AVCR, Blitz SBC-iD.

[Waldo]

thats the thing, they installed my apexi boost kit for the power fc, they said it wasnt working very well because it kept losing so much boost and couldnt hold it at 18psi at all, so i gave them my old manual boost controller, and they tuned it for 12psi and said that the manual one worked a bit better and wasnt so spiky, they still couldnt get it to stay at 18psi with the manual boost kit.

[Waldo]

do i need to get the wastegate actuator looked at and maybe modded to take the big boost spike from the ebc? could this be causing the big boost loss?

[Cubes]

Who's doing the work?

Steve with his HKS3037S had no issues holding 22-23psi.

Edited September 21, 2005 by Cubes

[Waldo]

i did all the work myself, im guessing the standard actuator cant hold the 18psi boost spike, its just the standard rb20 turbo actuator on a high flowed unit.

[yogi000]

the rb20det actuator holds 18psi with blitz spec S pretty steady. tapers off at the top end

[BHDave]

I found my stock actuator would drop back to 10-11psi at any boost above that.

An aftermarket adjustable would be well worth a look for 2 reasons: 1) you can set a higher base boost on the actuator and so are garanteed of that whatever your ebc does, and 2) The higher the base you set, the easier it will be for the ebc to do it's job and as a result you will have a more stable system with less spiking and a flat line to redline.

[predator]

I also have a feeling the stock actuators aren't that good at holding anything above 10psi, unless combined with a decent EBC to pulse it.. Mine can sit on 13-14psi, but always dribbles back to 10-11psi in the higher rev range.

It may be one of those varying things - some factory ones may be fine, others get old and not so good.

I've got an RB20 and RB25 actuator sitting around, should do a couple of swaps and see which is better (onto rb25 turbo).

[Cubes]

Modify the actuator bracket..

Elongate the holes, exactly the same as a adjustable rod.

Works well, I had my rb20det turbo holding a stead 16psi with no boost controller.

[predator]

yeah, thats a good idea.. 1 min with the drill, and you can still get a spanner down there to adjust. Which goes higher boost? pulling it in or out?

[Cubes]

pulling towards the front of the engine bay. So I guess thats out.

[Waldo]

how does this change the way it holds boost

[Cubes]

Flap doesn't open as wide.

Exactly the same way an adjustable rod works.

[Julzy]

i haven't thought about that, but its a good idea.

it just puts more force on the spring, meaning it requires more pressure before it opens up.

[Julzy]

Flap doesn't open as wide.

Exactly the same way an adjustable rod works.

<{POST_SNAPBACK}>

wouldn't it also effect the spring pressure though? meaning it will open up later also.

[Cubes]

No.

Boost ramps up harder.

Try not to think about it too much. It works, that is why adjustable rods were created.

The RB25/VG30 actuator is quite soft and can be adjusted by hand, the RB20 on the other hand requires a big dirty screw driver to be levered against the elbow.

Edited September 22, 2005 by Cubes

[Waldo]

ok so buy moving the whole actuator foward when the rod opens fully it is not open as much as it was originally, but doesnt a spring collapse easier once you have started to sqaush it. thus causing the wastegate to open earlier, or is it the other way around.

[huddy]

definitely gonna try this...