shanec

dk, where are you getting your info? I've not seen different numbers on how much the bottom end will tolerate with different kinds of FI. I am curious to know why the bottom end might be less tolerant of a TVS than a twin screw.

As far as the E-Force not being efficient, at 5psi it makes as much power below ~5300 rpm as a whipple with 10psi.

JDM and DynoJoe might disagree with you on E-Force's potential. Their cars are about to dip into the 9's.

dkersten

What most people don't consider is different FI setups have different amounts of parasitic power loss. For example, a turbo has almost no parasitic loss, just the inherent power loss you get from the backpressure when trying to spin the turbos. In that case, the power the crank and rods are seeing is pretty much the same as you see at the flywheel. A centrifugal or positive displacement supercharger is driven by the crank (via the belt), and can take from 30 to 80 hp to turn, so the flywheel hp is lower than what the rods and crank "see". The rods are the weak point in the stock short block. Kenne Bell has not seen a stock short block fail on their regular tune with 10psi since 2005 (when they were still trying to get the tune right). I have seen countless stories of people running 11 psi boost and blowing their stock engines (even saw one here at our track), but nobody blows an engine at 10 psi or less unless they try some crazy tune or run the wrong fuel. Saying "450 rwhp is the limit of stock engines" is wrong because many factors can change that number. 450 rwhp on a roots style with a 5 speed and factory driveline is pretty much the limit, but I can do about 480-500 rwhp on 10 psi at sea level with my KB and still be just fine - throw a set of lighter wheels on it, an aluminum driveline, and maybe an electric water pump, and you get 20-30 more rwhp, even though you are not making more power at the engine.

The E-Force is a roots style with the newer, more efficient generation 6 rotors. They have a twist like the twin screw, but still pump air rather than compress it, so they are very different designs. The twist in the rotors makes them quieter and more efficient. Being a roots style, they are still not quite as efficient, but between the rotor design, the longer runners, the bigger throttle body, and some other small design characteristics, they are quite efficient. HOWEVER, the rated "5 psi" marketing hype is 466 BHP, or about 400-410 RWHP, and being roots, at 6300 rpm you are at almost 7.5 psi of boost. A Whipple at 10psi with a stock TB and no other changes will get around 480 RHWP at sea level. So tell me which one is more efficient?

Now do some math - One PSI boost on a 4.6 will get you ~16 rwhp. A Whipple takes about 35 hp to spin at 6300 rpm, so all things being equal, if you took away 2.5 psi from the whipple example, you still see the E-force as taking about 40 more hp to run at that RPM. The older straight rotor roots superchargers can take upwards of 80-90 hp to spin at 6k rpm. The rods and crank are pushed harder to get the same power at the flywheel than any other type of FI.

JDM has a 600+ RWHP mustang with the E-Force, but it is a stroked and built motor with cams and heads, and the supercharger has a small pulley and a custom tune. I don't know what they are running for boost, but I guarantee it is more than 12 psi at over 6k rpm (you need about 13-15 psi to make that kind of power, even on a stroked and built motor). With a turbo at the same max boost, they would see 40-60 more hp at the wheels.

dolint95

he is right, there are alot of factors. I am running 10 psi paxton supercharger, with charge motion delete plates and NSR Blower Cam, Ted Jannetty Custom tune = 519 rwhp I have gone 20k miles so far, its my DAILY DRIVER....not even a sputter, glitch free, runs like a top. Crazy power............ So many people on this forum have told me that they hope I am saving up to rebuilt my motor...I don't see it happening, sorry guys

slickman

I know this is an old post but, I had to post this info. Last I knew JDM was running 17 lbs of boost with that setup.

908ssp

Something else new since this thread first appeared is you can now put a used GT500 blower the M122 from Eaton on a 3v with the DOB manifold. Makes good hp for a lot less money.