Forced induction on a 2.5 Liter 4 cylinder

atsakiri at ford.com atsakiri at ford.com
Fri Jun 7 11:11:31 GMT 1996


> >> The Whipple unit as sold by Keanne-Bell and Bell Engineering is the best
> supercharger. Gets boost lower and uses less HP. Tests done @ Ford show
> that Eaton, Paxton etc for 8psi on 4.6L motor used 70 hp to make boost
> while the Whipple used 35hp. Bell's kits are very well thought out. <<
> 
> If you test an Eaton supercharger at flow rates well beyond its design 
>limits, it MAY require 70 hp, but I have performance charts for the Eaton 
>Model 90 (Ford T'bird) and the Sprintex S102 (Whipple).  At 400 CFM and
>10 psi boost (more than 250 hp), the Eaton requires 28.5 hp and the 
>Sprintex requires 22.6 hp . . . better, but not exactly half.

The ~30 hp number is much closer to what I remember as the maximum 
power consumption of an Eaton Model 90 (1.5 liter) Roots blower.  My 
memory is harkening back to test stand (supercharger only) results
during my experience at Eaton's R&D Center in Michigan, working on
supercharger efficiency improvements.

The Model 90 may be undersized for a 4.6 liter engine.  That may
account for the 70 hp number.  If it does, it's certainly not an
indication that the blower is of poor design, just applied 
incorrectly.  It's also very important to test and compare just 
the compressors.  Intercoolers, ducting, etc. with flow restrictions
can have a large impact on the power consumption.  Eight psi at
the intake manifold doesn't always mean the pressure across the
blower or compressor is comparable.  The difference in power
might be due to the "kit" mentioned in the first post, not just
the blowers.


As an aside, the Eaton blower was in production before I got there,
so I can't claim any credit, but the folks I worked with did a 
great job all around (noise, durability, etc.).  Superchargers
aren't very common on American production cars, especially those
with engines as large as 3.8 liters.  They managed to overcome 
quite a few obstacles.  (Sorry for the editorializing.)


Anthony Tsakiris

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