[EQ Tuning]

Originally Posted by sperry

Thanks for the info Ed.

I'm still missing the advantage to the MBC. I understand the response limitations of the stock EBC, but I guess I'm just not seeing them as actual limitations. What sort of response gain are you getting? On my 2.0L w/ stock turbo, I was making full boost before 3000 rpm, and had zero driveability/throttle response issues... how much more can you ask for?

There are very significant response gains to be had with an MBC over the stock boost control system. While the low RPM boost threshold is lowered a bit because boost can ramp much quicker, the main gains are in the form of boost response during quick throttle transitions. Here's a little experiment for you guys to try with the stock BCS: Get in 3rd or 4th gear around 3500rpm, boost at part throttle to about 9-10psi for couple seconds, then quickly go full throttle and watch the rate at which your boost climbs. Now get to the same RPM and from cruising quickly go to full throttle and watch the rate of boost increase. You'll see that the ECU has to ramp boost much more slowly when starting from a bit of boost.

There are also very significant gains in the lower gears because with the MBC you can hit significantly higher boost levels than with the stock system due to the improved ramp rate.

Also, when I was running a MBC, back in the pre-reflash era, I was seeing spiking to 18psi, PTFB issues, no taper at redline, and tremendous swings in max boost due to weather. For example, the car would hold 17psi in the winter at our altitude with the MBC adjusted to it's lowest setting, I was forced to keep my foot out of the throttle just to prevent over boosting, and eventually just hooked the stock controller back up for the winter.

I certainly would never suggest running an MBC with a stock ECU, but with a reflash that is designed to handle part throttle, high boost conditions, there is no danger as long as the boost levels are appropriate. From your description, it sounds like you had one of the poorer designed MBC's out there. I have some experience with such units and I'll agree that their performance is no where near satisfactory. A unit like the Hallman really can't be compared to those old MBC's put together out of plumbing parts. The Hallman's springs are chosen for consistant, progressive operation, their RX model uses a ceramic ball which is much lighter than the standard metal ball, and the overall design of the body and the adjustment is wonderful. It doesn't require any tools to adjust, doesn't have any lock nuts, you just turn the knob and it stays put with even the harshest vibrations. I know this must sound like a commercial, but I have been really impressed with the overall quality, design, and performance of this unit compared to every other MBC I've used.

So, I understand that a MBC can be made to work well (though I would certainly get things tuned specifically for it), I just don't understand why anyone would replace a well designed OEM system with a $2 spring (and pay $170 for it). In my experience, the factory setup is far superior to a manual solution, even with the "limitations" inherent to the design.

The hallman unit can be had for about $80 which IMO is very well worth the performance gains for anyone who would benefit from the best possible response which includes pretty much any motorsport competitor or even just the "enthusiastic" driver.

Thanks
-- Ed