RobTune on restricted engine

[MConte05]

So I have sold off my NA 2.2L Legacy rally car, to buy a 2.2T Legacy rally car (Mike270's car). It is a stock engine with a manual boost controller and a catless downpipe, the cat is at the muffler so hardly a restriction.

Anyways, I was looking into the RobTune stuff since I wouldn't mind a small power bump for cheap, but was curious if anyone on here has run a RobTune on an engine with a 34mm restrictor, and if so how did it feel powerband wise.

I've been told that when stock, the restrictor is hardly noticeable because of the fact the inlet on the turbo is so small that it barely restricts the flow.

[robertpaige]

What do you mean by restrictor?

Also with the RobTune you get a pretty hefty power increase for around $600 with the ignition converter. (not including parts like upgraded turbo, injectors, etc that you'd need to have to be tuned for). You're looking at around $1000 for a RobTune package + VF39 + 550cc STi injectors + N/A fuel rails (cheap) and maybe a lil more if you need an Intercooler or fuel pump.

[IronMonkeyL255]

By restrictor, he means an inlet air restriction pre-turbo with a diameter of 34mm. Required for his rally class, I would take it. It is the same kind of thing they used on the WRC cars to restrict power output.

[MConte05]

Yep, you are right:



Basically a small machining that attaches to the front of the turbo to restrict the amount of airflow the turbo can suck in. 28 lb/min is generally the choke flow so lots of turbo rally cars run out of steam after 5500 RPMs or so.

Was really hoping that maybe someone has, or knows of someone who has dyno plots of a 2.2T on a restrictor or even better, a RobTune on a restricted engine.

[James614]

I feel like it would be worthwhile. Even with a rob tune, the stock heads and cams are in their sweet spot in the mid range. 5500rpm is where the stock powerband falls off anyways IIRC.