More info on the popular compound boost combination
MM&FF first broke a story about compound boost in the January 2008 issue-you can read about it here.
It detailed the installation of Hellion Power System's latest turbocharger kit on a 2004 Cobra. We ran twin turbochargers blowing into a stock engine that continued to utilize the Eaton supercharger. The supercharger compounded the boost to unbelievable levels, as well as providing a serious punch down low; something large sized twin turbo kits lack when on Modular engines.
The response has been overwhelming, as Mustang shops, Internet message boards, and bench racing sessions across the country have lit up about this new system. The technology is certainly not new, it has been in the diesel world since the '60s and tech extraordinaire, Richard Holdener, has cited uses of compound boost in the aviation world before then. OEM manufacturers employ turbo/supercharger combos in many different models as well. Hellion is credited with bringing this concept to the Mustang world. I am still shocked and overwhelmed with the responses I have read and heard about from many different sources. It is great to see this concept is, perhaps, the most talked about topic in the Mustang world right now.
The story covered a great deal of information about the system but there are still questions and concerns surrounding compound boost. First, the blower is not so much of a restriction as one would think. The biggest problem with running the blower is the fact that it takes power to turn itself. That knocks off total output a bit, but the bottom end gains far outweighs the top-end charge in street application. Thanks to testing by Dez Racing, reports are that adding a Stiegmeier-ported Eaton did help efficiency and added more power over a stock Eaton blower.
Mike Dezotell of Dez Racing recently added the Eaton blower back to a customer's twin turbo 2003 Saleen-Cobra. It has an HP Turbo twin kit onboard and once the compound boost story showed up on our pages, the guy went to the shop for the conversion. Dez reports the car made 1,020 rear-wheel horsepower and he commented the street manners are much better. Torque output was 1,018 rwtq. The car is very responsive down low and the tires get blown away easily when rolling into the throttle at 70 mph. As Dez stated, "We are having a lot of fun and this car is tops."
The shop added a killer fuel system but the owner only had 75-pound injectors, so Dez relied on an Anderson Ford Motorsport Mr. Freeze meth injection kit to get away with the small injectors. Dez used SCT software to re-flash the computer with the correct tune up and didn't have any problems with the stock electronics. Pump gas was drained in favor of C16 race fuel. Total boost output was 36 psi and the engine is stock.
John Urist called me to let me know he is in the middle of testing the twin turbo setup without the blower. They were testing several different turbochargers, just to make sure all applications are covered properly. The Hellion kit is available with or without the blower setup.
People are asking what will a Whipple or Kenne Bell blower do with a set of twins blowing into the throttle body, we don't know and hopefully someone will do it soon so we can find out!