hey guys,

got my exa turbo and it's boosting at 7psi, how do i turn it up to like 10psi or so?

many thanks

nicholas

Turbo boost maximum level is maintained by the "wastegate". Turbos have either an internal or external wastegate.

A wastegate is designed to "redirect" air around the exhaust turbine, so the turbo maintains its speed once it hits the boost limit specified by the factory, instead of rising with engine revs until redline.

All boost control mechanisms rely on "tricking" the pressure signal sent to the wastegate actuator. By "bleeding off" pressure signal to the actuator, the boost produced by the turbo will be raised as the exhaust gas is allowed to spin the exhaust turbine faster than normal.

People who upgrade their exhaust, also see rises in boost, sometimes as much as 3psi difference.

How to rise your boost, buy a boost controller or boost bleed valve. The boost controller will generally give you a more consistant rise in boost, as it should be able to monitor what it is doing.

People also put a spring onto the wastegate actuator to make it open more slowly.

The actuators rate of opening and the wastegate's port size will determine the boost control characteristics.

There you go.
Chris

ps. Sorry there is no screwdriver adjustment for boost control.

Hey turbo xs make a screw driver adjusted bleed valve.
Or for some real fun just pull off the rubber hose going to the wastegate

yeah like chris said. cheapest and easiest is a spring on the wastegate.

I've got a turbo XS bleed running on mine and it holds boost really well, no falling away or anything like that. (and like NIS said, screwdriver adjustable)

I've seen a little switch on the dash of an rx7 before... runs at around 8 psi or something, and then flick the switch and it goes up to 10-12 psi...
fun!

that's 2 stage boost control. It's easy to wire that up.

All you need is a vaccuum solenoid (free->$5 from wreckers), a bit of wire, 12v, and plumb that into the line. off position for switch means regular boost 6-8psi, and with switch on, whatever you set your boost controller/bleedvalve to.

Too easy.

i've also noted that when i change gear i have to wiat for it to boost again before it really pulls.??? if i fit a boost controler will i get that chssssshhhh noise? and were does it fit?

many thanks

The Chshhhh noise is a "blow off valve" or BOV. Which is a completely separate thing.

It plumbs into the high pressure side of the intake tract after the turbo. It is activated by high vaccuum inside the intake plenum. The vent (the noise), can either be "atmo vent" or "plumb back", or hybrid (meaning both).
It is designed to keep the turbo spinning slightly longer. IT is supposed to make the turbo last longer, but this is theoretical. Many factory turbo installs don't have one.

The wait between gears...that's "turbo lag".
The turbo on your EXA is obviously a little too big. Fitting a smaller GT25 Garrett turbo will rectify that...welcome to the club where an open wallet is a common sight.

hey datodude,

have you got the ignition timing specs for the n12? cause on high rpm it pings abit.

as for the bov does it connect onto the manifold or buy the trottle body?