Blitz Dual SBC Spec S boost controller:have I reached its limit?

[soldave]

Will report on my tuning session this evening a little later, but a question for you all first. I am currently using the Blitz Dual SBC Spec S boost controller to handle my boost and I am wondering if I have reached its limit. Here is my situation. I had the boost controller ratio set to 75 which was giving me 1.3bar/19psi of boost pressure with a spike up to 1.45bar/21psi. Tuning was going well so I elected to turn up the boost. However, turning it up didn't really do anything. The only thing that happened was the boost spike increased, ending up spiking to 1.75bar/25psi when the ratio was set to 93.

I have seen figures banded around the net that say the Spec S boost controller is good for between 1.3-1.5bar(19-22psi) and above that you need the Spec R which has a dual solenoid. Would this be what happens if the boost controller is reaching its limit? The only other thing I can think of is that the internal wastegate on the turbo can only handle 1.3bar/19psi, but I sincerely doubt that is the case. Am going to email Bullseye about that though. Could also be the Greddy Type S BOV leaking although I am doubting that one.

Finally, if it is the boost controller reaching its threshold, am I right in thinking the only difference between the Spec S and the Spec R is the solenoid, so I can just buy the Spec R solenoid and keep my actual controller box?

Thanks for any advice you can offer me on this one. I am sure I can get the boost up to 1.5 bar/22psi as I'm hardly running into any knock at the moment.

 

[Killa_dsm]

I had a similar problem with the exact same boost controller. The only solution I found was to adjust the preload on the actuator. If your actuator is adjustable I would try that out. Its been working pretty nicely ever since I did that.

I'm not much help but I hope that helps. I have no clue about swapping out the solenoid on the R and S.

 

[soldave]

Hmmm... I think the actuator is adjustable but I'm not 100% sure. Did adjusting the actuator also get rid of a boost spike for you, and what kind of boost were you dealing with?

Incidentally, Incidentally, Blitz UK have just replied to me telling me it sounds to them like I have reached the 1.3bar threshold of the Spec S. Now whether that's true or whether the ctuator is to blame I'm not 100% sure.

 

[Killa_dsm]

I didn't really have much spiking before and after adjusting the actuator. I was only able to run a max of 21psi without stiffening the preload on the actuator. But after adjusting the actuator I am able to run 25psi+.

If you do adjust the actuator be sure to lower the settings on the boost controller before doing a run.

What is your Gain set to?

 

[soldave]

Gain is set to 8 at the moment. Could it be that there is just under 2ft of vacuum line between the actuator and the actual solenoid? Will try adjusting the actuator this weekend and see what happens.

Bullseye said they have had people holding 30+psi on this particular turbo.

 

[Killa_dsm]

Just a theory but maybe the Spec S solenoid starts to leak at higher boosts. So by stiffening the preload on the actuator it prevents the little amount of boost leaked by the solenoid to open the wastegate? Not sure if that makes since but thats one idea that just popped into my head.

With the boost controller set to off (actuator pressure) I see 18 to 19psi. Thats how stiff I have my actuator preload set to. And I use the boost controller to run anything above that. I can get exact settings of my Blitz boost controller this weekend for you when I get home.

 

[soldave]

If you could let me know what your settings are, that would be great. And also what turbo you're running.

Am thinking/hoping maybe stiffening the preload on the actuator will sort out my problem. Is that an easy thing to do?

 

[Killa_dsm]

I'm running a PTE 50 with a internal wastegate. Adjusting the actuator is pretty easy. Just pull the end of the rod off the wastegate flapper and tighten the fitting on the end of the rod.

Here is a example of what the adjustment rod looks like. Just tighten the fitting on the end of the rod (on the right).

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[soldave]

When I had a good look at the turbo there was no preload on the actuator at rest. Had to tighten the adjustment rod on it 2 full turns to get a bit of preload. Am now holding 1.45bar with a spike to 1.62 which is manageable. So problem is solved. And even better, my Rev/Speed meter is now reporting 380hp at the higher boost level, and thats with knock and lean fuel maps. The 400hp mark isn't too far away!

 

[Killa_dsm]

Good to hear you got the problem solved. Now get the spiking issues fixed, .

 

[soldave]

Yeah, not sure what I'm gonna do about this spiking. Am thinking it's gonna be a little higher if I'm launching and going through the gears too. The gain on my boost controller is already pretty low.

EDIT: Would shortening the hose from my turbo to the boost controller solenoid help at all? It's currently about 2ft in length as the solenoid is placed over near the air filter.