ATP Boost Cut Defender question

[AutoEuphoria]

I have a Turbosmart MBC and an ATP BCD. I bought them both used. I initially installed the MBC and set it in the range for the boost I wanted (about 17), then installed the BCD and turned the MBC up a click or two to get near my final goal of around 18.0 to 18.5 psi. I noticed that my AFRs were really low (around 8 or 9), and the DashHawk was reading really low boost (showing 5-6 psi when I know I was in the range of 18-18.5).

I figured this would happen because...well, that's what's supposed to happen. But it got me thinking...am I losing more power by running so rich than I am gaining with the extra psi of boost? Is there a way to adjust the ATP BCD so that it reads closer to 15 psi rather than 6? I have the BCD off right now, and the MBC set to 17.5psi. I'm seeing AFRs in the 10-11 range in higher RPMs at WOT. I am, however, still hitting boost cut every once in a while, and I'd like to eliminate this by re-installing the BCD, but I don't want to end up losing power from the added fuel choking things down.

 

[lestat13]

The Dashhawk is reading what the ecu thinks it's seeing (different than what you are running because of the bcd). You need to install a real boost gauge so you know what boost you are running. I would turn the mcd down until you know what you are at cause you might blow something up.

 

[AutoEuphoria]

I understand that, and appreciate the response...but that's not what I was asking.

What I was asking was if the added fuel from running rich (the BCD makes the ECU think it's running lower boost than it is, and dumps more fuel in than it would at the higher boost levels) takes away more power than having that extra PSI of boost gives...basically, I can run 17-17.5psi without the BCD and see good AFRs the whole way through the RPMs. If I want to run 18+ psi, I have to install the BCD to prevent boost cut, but that makes the car run REALLY rich (AFRs in the 8-9 range). Running really rich cuts down on power (compared to being leaner...leaner makes more power to an extent, but things get hotter and fail faster).

I also wanted to know if there is a way to adjust the ATP BCD so that it doesn't make the ECU think it's running such low boost pressures (5-6psi range...would like it to see closer to 10-12psi instead). If I could do that, it should run leaner, have higher AFR in the 9-10 range (acceptable), and cure both problems.

 

[Speed3Rookie]

Good questions.
Looks like you are only wanting 1-1.5 lbs more boost and you're having to use the bcd and the mbc to get it. Don't you think it would be better to stop at 17.5 and not have to use the bcd? Do you still get boost cut with 17.5 lbs?

 

[AutoEuphoria]

That's what I was thinking...plus, I'm able to still get a really good (accurate) measure of boost from the DashHawk, which comes in handy when datalogging. I don't get boost cut from 17.5psi, but for some reason I sometimes spike above 18psi and hold there a fraction too long and it gets me. It's not all that consistent...temperature could be affecting it a bit, and I do know that I had it hooked up incorrectly for a while. I don't see it as much now, but I am not 100% confident that it won't happen again.