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Hey all, first post, I’ve come here for help as I can’t find any information elsewhere. I recently purchased a Blitz SBC type S and installed it on my r33 GTST. Car is almost completely stock except for exhaust and filter. The issue I’m having is my car boosts to roughly my target (12.5-13 psi) and then falls off in the high end to around 4-5 pounds of boost. The controller has 3 settings, duty, gain, and p gain. Has anybody experienced this or have a set of settings that works for them that I could steal? There’s next to no information on the internet on this particular boost controller and the translated manual is basic at best. Thanks in advance 

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What are you doing for management? You can't run 13 psi on a stock RB25DET ECU. It will tell you to go stuff yourself and give the engine all the fuel and none of the timing.

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12 minutes ago, GTSBoy said:

What are you doing for management? You can't run 13 psi on a stock RB25DET ECU. It will tell you to go stuff yourself and give the engine all the fuel and none of the timing.

Maybe that’s my problem then, ecu is stock. I was of the understanding that guys could push around that but not past 14 without grenading a turbo on more or less stock everything but perhaps I’ve been mislead 

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The turbo's limit is ~14 psi (subject of course to the truth that these are statistics and some die at stock boost!).

The ECU has a strategy called R&R, Rich & Retard. It is basically just the high rev-high load part of the fuel and spark maps have massive fueling and very retarded timing, as a self protection mechanism. Makes the engine hard to grenade. It actually makes the car hugely slow, the more boost you add.

About the max boost you can usually give an R33 ECU is about 10 psi. Maybe 11. Usually starting to get ridiculously rich by then though, and all you do is use more fuel to go no faster, if not slower.

RB20s, by contrast, will more happily run up to about 14 psi on both the turbo and ECU. The ECU has R&R type stuff going on, but it doesn't act as early as the R33. On my R34 ECU I have had to tune out a lot of fuel and add a lot of timing just to get it to run ~12 psi (which is the hardest I am willing to run the turbo - it probably could take a bit more though).

As to your boost controller. It doesn't matter what controller make/model really. They all use the same basic functions. Look up the guide for a Profec, for example, and see what the advice is. It doesn't matter what the actual values of the numbers are. Just what the changes to those numbers cause. Turn the gain up and the boost should go up. There's usually one of the settings will set a point below which the controller will try to keep the wastegate shut, to help speed up spool. Increase that and it will come on harder, but might spike into overboost. So you set the gain, then fiddle with the ramp setting. Then you look to see if it is losing boost at high revs or if it is not controlling properly (is boost is rising above your gain setting) and use the third control variable to increase or decrease that behaviour. If it's dropping boost up high, you generally increase the third setting. And vice versa.

Just fiddle with it and you'll see.

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12 minutes ago, GTSBoy said:

The turbo's limit is ~14 psi (subject of course to the truth that these are statistics and some die at stock boost!).

The ECU has a strategy called R&R, Rich & Retard. It is basically just the high rev-high load part of the fuel and spark maps have massive fueling and very retarded timing, as a self protection mechanism. Makes the engine hard to grenade. It actually makes the car hugely slow, the more boost you add.

About the max boost you can usually give an R33 ECU is about 10 psi. Maybe 11. Usually starting to get ridiculously rich by then though, and all you do is use more fuel to go no faster, if not slower.

RB20s, by contrast, will more happily run up to about 14 psi on both the turbo and ECU. The ECU has R&R type stuff going on, but it doesn't act as early as the R33. On my R34 ECU I have had to tune out a lot of fuel and add a lot of timing just to get it to run ~12 psi (which is the hardest I am willing to run the turbo - it probably could take a bit more though).

As to your boost controller. It doesn't matter what controller make/model really. They all use the same basic functions. Look up the guide for a Profec, for example, and see what the advice is. It doesn't matter what the actual values of the numbers are. Just what the changes to those numbers cause. Turn the gain up and the boost should go up. There's usually one of the settings will set a point below which the controller will try to keep the wastegate shut, to help speed up spool. Increase that and it will come on harder, but might spike into overboost. So you set the gain, then fiddle with the ramp setting. Then you look to see if it is losing boost at high revs or if it is not controlling properly (is boost is rising above your gain setting) and use the third control variable to increase or decrease that behaviour. If it's dropping boost up high, you generally increase the third setting. And vice versa.

Just fiddle with it and you'll see.

Oh okay that makes sense then. I’ll keep fiddling with it but from what you’ve said it seems like I probably just tried to shoot for the moon and it pulled timing on me. Appreciate the fast response, it’s my first year or so with the car so pretty new to it’s quirks.

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