Increasing Boost

[Trip]

Car is currently running at 10psi with boost controller (Blitz Dual SBC) set at 25% gain. Today i took car for testing to increase the boost a little . I turned gain setting to 50 but it only went up to 1psi. Turned it to 100% and got 12psi. . I wanted 15psi (1bar).

I disconnected the boost controller soleniod vacuum hoses and put a manual bleed valve. Fully closed i was getting 8Psi, I opened it and max i was seeing was 10psi.

I completely removed the vacuum feed going to actuator and the boost exploded up to 18psi. I am sure it could go more but i immediately backed off the throttle.

Tinking about it on my way home, the actuator is a new 11psi one which should in theory with bleed valve closed or boost controller off should give me 11psi.

The turbo is a standard one which does have one hairline crack around the wastegate port. Could it be this is my problem. I do hope so cause tomorrow will be my last race using it.

 

[PobodY]

Isn't the gain setting on the SBC just to fine-tune the feedback from the sensor; you're just calibrating it so it reads the same on the SBC as on your boost gauge?

You want to play with the boost ("set point" maybe) value instead?

 

[Trip]

I know what you mean. I meant i adjusted the main setting to "gain" more boost. It has 4 settings. the real gain setting is set at 5.

 

[Braveheart]

I am not familiar with that particular boost controller but that does not sound like it's working... unless as explained, you are not actually adjusting the boost setting. A few degrese on mine gives a few more psi. Maybe talking to your solinoid or you have dirt some where in the device.

 

[red reading]

have you got the com and n/o ports coneected the wrong way round? if you have it will give the symptom's you discribe.

 

[Trip]

They are installed correctly, When i removed them to put the bleed valve in, i took a peep at the manual to make sure I install them correctly. IN is vacuum soruce and OUT is connected on actuator.

If the problem is the soleniod, It is working up to a degree since it did increase boost from 8psi to 12psi. But how come when i used the bleed valve it did not go past 10psi either.

I have a spare soleniod of the spec S type SBC, and if i find time before the race, i will wire it instead of the Spec R soleniod and test it out.

 

[Trip]

I put in the Spec S soleniod, and put 50 Percent on the boost controller. I got average of 11psi. The boost flactuates between 10 and 13psi.


check out a graph from my datalogger

 

[MarkTurbo]

The turbo is a standard one which does have one hairline crack around the wastegate port. Could it be this is my problem. I do hope so cause tomorrow will be my last race using it.

I've had 20psi out of a turbo with a cracked housing, how big is the crack?

 

[Trip]

I've had 20psi out of a turbo with a cracked housing, how big is the crack?

No idea how to quantify the crack but it is visable with the naked eye. The turbo did boost to 18-20psi when i removed the vacuum feed going to the actuator.

 

[williams]

this is the problem i had, did you fix it? i hope its not the solenoid?

 

[red reading]

Have you tried reversing the solinoid pipes??

 

[williams]

Yeah, I just get standard boost that way. I get *bout 20psi with no pipe on actuator. And can get up to 1 bar using controller.

 

[jambo_gtir]

You sure the actuator isn't dogey?
If the problem is still there when you remove boost solanoid and replace it with a manual bleed valve; then surely that negates the boost controller. Sounds like the actuator might be faulty, or wrong spring in there?
Just an idea......

 

[williams]

i'll test actuator next week.