Two Level Boost

[Meddy]

OK. To throw a spanner into the works...

It does the spike when running with the EBC off and just the actuator adjusted up. It also does it with the EBC bypassed through my own finely adjustable version of the Apex Performance boost valve...

A thought has occured to me about something which may *possibly* have an effect. I'll try it at lunchtime. Its off on a complete tangent, but is linked to the car's boosting...

How do you have the actuator set its not bottoming in the can is it? Can you bung on a OEM one?

 

[Nicely]

I tested the actuator with the adjustable on the old turbo. The new turbo has the OEM fitted...

 

[Meddy]

I tested the actuator with the adjustable on the old turbo. The new turbo has the OEM fitted...

Ah well ok thats my ideas done with then.

 

[Nicely]

:nod: You see my problem... Its a head and brick wall thing...

So, should boost creep be a gradual thing rather than instant, like I've got?

 

[S15R]

stock manifold will spool the turbo up faster than an aftermarket equal length manfiold

 

[Meddy]

:nod: You see my problem... Its a head and brick wall thing...

So, should boost creep be a gradual thing rather than instant, like I've got?

If its the wastegate just struggling then its going to be gradual as it will just slowly build as engine load does.

Thats why everything points towards something in the control circuit. Theres just nothing mechanically I can think of that is going to so suddenly give spiking.

 

[Nicely]

I just eliminated my idea. Disconnected the power to the carbon canister solenoid. No change

Fart. Don't really want to get another EBC.

EDIT: Actually, I've just realised. I haven't completely bypassed the EBC. I ran the boost valve in parallel... So the EBC could have been leaking at the same pressure level Damn! Got no way to test just the valve as I've go no stand alone boost gauge and the EOM only goes up to 1 bar...

 

[yewei]

hey nicely, thanx for the advice n showing the steps of removing the mani :thumbs: i have only remove 2 screws from the heat shield, got 3 more to go, which is a pain in the ass becos they won't loosen up, and to make things worse. seems to me head of the screws have become "round" how am i ever going to remove the heat shield? cut it open?

 

[Derek]

Nicely, I have Tubular manifold and Turbo Elbow now fitted with few days. I'm holding a steady boost of .7bar now. I was boosting a little high. 1.4 and 1.5 but that was down to me. I had the Boost pipe Tee'd into the pipe running into the Carbon canister where i have found out that there's no Vacuum in.

 

[I-nearly-bought-a-batty]

What settings do people have their Profecs or SBCs set to boost and gain-wise?

For my Profec B, the high boost is set to 1.1 bar (this somtimes spikes to 1.2 on occasion - once and only once on a cold night - it hit 1.35 ). Low boost - never use it but it's set to .8 bar. Gain? It's set to max! - wind it right off the dial .

Boost unsurprisingly comes on real quick!

 

[I-nearly-bought-a-batty]

Looks as though its boost creep. Its taken a year, but I finally got a diagnosis off one of the SXOC Mods

Disconnected the actuator arm from the turbo and tied the wastegate flap open. This should ensure that zero boost can build. Floored it in 5th and 6th over the usual peak power points where the problem usually occurs. Boost started building as the revs increased and peaks at 0.5 bar. With the wastegate fully open...

This means that the wastegate isn't large enough to allow the boost pressure to escape quick enough to keep up with the flow of the exhaust.

Three options:

1. port the wastegate slightly larger. This is a documented and proved process.
2. fit an external wastegate. Expensive and a ball ache.
3. fit a smaller turbo elbow/dump pipe to increase the amount of back pressure and slow the flow.

Now, Meddy had a near identical spec to me and never encountered boost creep. The only major difference in spec is that he still had the standard manifold. I've got to think about it, but I'm seriously considering fitting a standard main back on...

To those with a tubular mani, you may well find you have the same problem once you try to boost over 1 bar if you have a T28BB...

95% of the time I have no boost creep problems - running 1.1 bar, standard manifold with 3" off the turbo. The standard manifold might be the answer.

 

[Meddy]

Sorry to drag this up here but Ive got a question for you Nicely. Before I strip the old turbo I just want to be certain it is actually faulty as at present Im not convinced there is anything wrong with it. I agree there is a bit of axial play, but I dont think this can be the bearings as theres no radial play which you would expect if the bearings had worn. I think the play might be just the bearing cartridge moving within the space allocated to it. They are held in place by a dowel pin which looking at the patents Ive got access to looks a pretty loose fit.

So how much more play do you think there was in this unit?

Ive asked a supplier for the tolerances allowable on axial movement but Im not sure how long a reply will take.

Cheers. :thumbs:

 

[Nicely]

I would agree that it appear the turbo was not at fault, and, although well used, is probably fine. In terms of the size of the impellers, the difference in play was 'noticeable'. That was how my engineer mate described it. I noticed more play, but wouldn't know whether or not is was vast.

Incidentally, HKS EVC on its way....

 

[Meddy]

I would agree that it appear the turbo was not at fault, and, although well used, is probably fine. In terms of the size of the impellers, the difference in play was 'noticeable'. That was how my engineer mate described it. I noticed more play, but wouldn't know whether or not is was vast.

Incidentally, HKS EVC on its way....

Best bet the EVC's are by far the best units IMHO. :nod:

Incidentally if it turns out the tubby is ok how many pennies are you after for it. PM me please. :thumbs:

 

[S15R]

my blitz id 3 is always been on auto, whats 0.9bar in Manual?

 

[Nicely]

Well, in our colder climate, I have mine set to 62 and a gain of 5 and got a fairly consistant on 1 bar.

 

[S15R]

Thanks Nicely, with the 62 and a gain of 5 setting, i assume its without the HKS actuator?

 

[Nicely]

I believe that's what I set it to for the new turbo, so that's with an OEM actuator You can set it to a gain of 10 for quicker spooling, but just lower the boost figure slightly until you've seen the peak.

 

[S15R]

Mines set on auto at 0.9bar with GAIN on 7 and it never reach 0.9bar peak was 0.82bar this morning...

thats why i wanted to try out the Manual Setting, i might play around with it tonight.

 

[S15R]

quick question,

I've connect the vacuum tube to the pipe that goes to the BOV, if thats ok?
i was told to use the hose to the FPR but im also worried about the plastic tube that blitz provided will melt

also, i'd like to know where is the stock boost gauge sensor connected to?

Thanks