[Mk2] [Turbo] Full boost by 6000RPM...surely not

[SWMark]

Morning fellas and ladies,

Having a bit of an issue with my Rev3 tubby. Spec is:

AVCR
Apexi filter
3 inch downpipe and system.
Magnecore leads
NGK grade 7 or 8 plugs(i forget which grade but fensport recomended them).

I was having all sorts of wierd boosting problems with the avcr but no leaks or anything so i turned the avcr off thus running actuator boost. The behaviour iss odd, it hits about 0.63bar at around 4 then slowly creeps to about 0.75 by about 5K then peaks at 0.95bar at just over 6K.

What would be causing it to take so long to boost? Could it be a loose actuator or perhaps a blowing exhaust fannymold?

Any ideas would be much appreciated, cheers guys

Mark

[Slarty]

It could be that the wastegate is fouling on the DP, but you'd have to remove the DP to check for that.

Or it could simply be boost creep due to the poor design of wastegate on the CT series turbo. Welcome to my world

3" Aussie DP and a 3" blitz, running actuator pressure only I get pretty much the same symptoms as yourself. 0.6-7 bar at 3.5k RPM and then anything upto 1.2 bar at 6k RPM.

[Ja99a]

Mate this test is one you need to be really careful with and not go bananas and boot your motor, disconnect the wastegate and bung up the pipe, now go for a drive and see how you boost, as the waste gate is disconnected you need to be careful as the skys the limit in terms of boost. I can't strees how careful you need to be....

The boost should climb really quickly, if it does not boost like this then you have problems with either the wastegate not fully closed or the exhaust is finding a way past the exhaust turbine.

(This assumes that the turbo is in good nick and spins freely etc).

[Driftlimits Performance]

I can't acutally believe you just recommended that!





sounds like the wastegate isn't closing properly in my opinion.

[karammander]

very risky doing that i agree, my uncle's wastage pipe blew off on his punto gt and we saw 2.2 bar at around 3k for a second before we shat it. dont do this.

cheers karam

[SWMark]

Hey Fellas,

OK , so what could be the problem as to why its not closing?

Mark

[raze tekniq]

I had the exact same problem, so I changed the acuator for an adjustable type. This sorted the problem of slow boost but it now boosts up to the fuel cut 1.2 bar. Apparently the 2's can run up to this on standard internals and I've had no ill affects yet, apart from the fuel cut.

[raze tekniq]

sorry button got stuck

[raze tekniq]

I had the exact same problem, so I changed the acuator for an adjustable type. This sorted the problem of slow boost but it now boosts up to the fuel cut 1.2 bar. Apparently the 2's can run up to this on standard internals and I've had no ill affects yet, apart from the fuel cut.

[TheRoadWarrior]

As i understand it, running on actuator only can give this kind of behavior- the actuator is a spring dont forget, so it doesnt open 'digitally' at 0.9bar, it will crack open a bit before, then open further as the boost builds.

If you want to test it without the avcr, plug the T-VSV (i.e the factory boost control) back in and run it again, then report back. Should boost to .9. If it doesnt check for error codes.

[Driftlimits Performance]

Wiggle the actuator rod. You'll feel the wastegate tapping around.

That means it's lose, and exh gas is creeping away from the turbo, hence it's not spooling up until hi RPM.
Change actuator.

[MATTGT4]

I am also having the exact same problems with boost on a rev 3 conversion, i replaced my standard ct20b actuator with a forge one and the car still overboosts the same as before.

[raze tekniq]

Have you managed to sort out your forge acuator? mine's doing my nut but in fairness I haven't had the turbo out to sort it. Making the rod longer should sort the boost out.

[dude541]

the forge actuators can come with various pre set springs,you really need to know whats inside it before making any adjustments.
john

[jonb-]

very risky doing that i agree, my uncle's wastage pipe blew off on his punto gt and we saw 2.2 bar at around 3k for a second before we shat it. dont do this.

cheers karam

My boost controller suck shut, I hit 1.6 bar and fuel cut twice! Engine is still fine a track day later.

Boy it flew too.

[raze tekniq]

the forge actuators can come with various pre set springs,you really need to know whats inside it before making any adjustments.
john

Is there any way of getting the spring changed do you know?

[dude541]

the forge actuators can come with various pre set springs,you really need to know whats inside it before making any adjustments.
john

Is there any way of getting the spring changed do you know?

yes they come apart so you can change springs/diaphrams etc

http://www.forgemotorsport.com/content. ... nc=product

[raze tekniq]

Cheers I didn't know that. Would you have any recommendations which springs to go for. I just want to run 1bar at the max.

[dude541]

my old set up was a 12psi spring,then used a boost controller to take it up to 1 bar,less chance of spiking that way.
john