I know that at 3500 rpm the boost is 20 psi and at higher rpm it tapers off. But it feels like when i am in the higer gears, (4th and 5th) the boost works down a bit lower in the rpms, like 3000 or so, but in the first 3 gears it dosent feel like it kicks in till 3500-3700 or so? So when does the boost actually first start to work in each gear, is it always 3500 and never earlier on a stock IX?

 

Lmao.. There is no 'set' spot the turbo starts to work in.. The spool up depends on lots of things such as size of the turbo, load on the vehicle (gear), motor size, etc...

PS you better put your flame suit on...

 

It also depends on throttle position. BIG factor.

 

so for the evo engine and twin scroll turbo charger fitted to it, when at the earliest rpm would the turbo start working? If your holding the throttle to the rev limiter at a stand still will the turbo be working from the launch right through all the gears if you shift at the right rpms?

 

That is absolutely correct.

Typically totally stock it should start to spool up around 3000rpm. There are things you can do to improve your spool up like a TBE to remove back pressure or a ported manifold. Tuning can also further improve spool up.

 

It is all about load. I will hear my car blow off when I leave off the gas under 2k RPM going up a steep mountain road. The car feels like it is going to bog out and die but the boost is at 8psi or so. On these cars it is really about load on the engine. But I think your real question is where does boost kick in under normal driving conditions on a flat smooth road. Most dyno pulls show around 3400 RPM on a stock car for full boost. This will be a bit less on the street from what I have seen over the years.

 

thanks TURBev08, nice description, just what I was looking for.

 

20.16 psi @ 3500 (wot)

and tapers off to

16.10 psi @ 6500 (wot)