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Bruce Wood, director of
Cosworth's CART Champ Car program, was on hand for the opening
of CART Spring Preview testing at Mazda Raceway at Laguna Seca
(Calif.) today. Wood discussed changes made to the Ford-Cosworth
XF over the winter as the turbocharged powerplant heads into
its third and final season.
BRUCE WOOD, Cosworth Racing
CART Program Director:
"Of the three major areas that we focused on this off-season,
combustion was the main area we looked at. When the engine
was first designed, it was designed for 40 inches of boost -
about 10 above atmospheric. So, this season, we're down to 34
inches ...and we've lost about 60 percent of that boost
pressure. That's an enormous amount. The design of the
combustion chamber ... the profiles and the volumes ... were
very much designed around the boost, so therefore, there's
quite a difference between 34 and 40 inches of boost. When we
made the change from 40 to 37 inches of boost for last year,
we chose to live with the compromise in terms of the
combustion chamber shape. However, this year it would have
been too big a compromise, so we ended up doing a lot of work
there.
"We also did a lot of work on
engine speed. That's one of the things last year where we
felt in our qualifying performance on the road courses was not
where we wanted it to be. We ended up qualifying very well on
the speedways, but not so well on the road courses. Engine
speed can play a big part on the road course, especially if
you can run the engine fast enough that you can miss out a
gear shift. Although gear shifts these days are still very,
very fast, they still do take a finite amount of time. If you
can miss out a gear shift, there's something to be gained
there. In the slowest corners, if you have a higher maximum
rev, then the engine won't run so slowly in the slowest
corners. It's very difficult to make the engine run very
slowly and pick up very cleanly, so the less revs you can drop
in a corner, the better. So, we felt we wanted to bring our
revs up to improve our qualifying performances. With the new
qualifying rules (two additional points available, announced
by CART today), it will be especially important to improve our
qualifying situation. We looked at the revs for qualifying,
specifically about 500 rpms, and in race trim we've looked at
about 200 rpm.
"The third area we looked at
quite a bit was in the area of breathing. We looked at the
port profiles and the cam profiles in particular, and we
managed to get some performance out of that. So those are the
three major areas we concentrated on."
CAN YOU DESCRIBE THE HORSEPOWER
YOU'VE LOST DUE TO THE BOOST REDUCTION? "The first step, from
40 to 37, was probably worth 75 horsepower, and the next step
(from 37 to 34) was probably another 65 horsepower. Of that,
we've clawed back with some gains. At the end of last season,
we clawed back about 50 of that. This season, we've only
clawed back maybe 15 of the 65, and I'd hope there's probably
another 10 to 15 more we'll get back before the end of the
season. I'd say we'll be lucky to get back half of what we
lost this year, but you get to the point of diminishing
returns."
IS THERE ONE SPECIFIC AREA YOU
WANT TO WORK ON THIS YEAR DURING THE SEASON? "We're actually
going to concentrate on the smaller things, if you like. In
the past, we've always had another season's engine to be
looking at, so if we wanted to make some big architectual
changes ... in the past changes the angle, or the bore sizes,
etc., etc. Those were major investments in both of time and
money. So, in past years we've had to pay attention to those
things because they do take time and money, and we're started
looking at them early in the season. This year, knowing
it's the last year for this engine ... a turbocharged engine
... we don't have that distraction, so we can start going back
and looking at things that have slipped through the net, so to
speak ... simple things like oil testing. In past years,
we've found horsepower through working with oils, but we
haven't really looked at those things as much because we've
had bigger fish to fry. Now, this year, we're going to turn
to the smaller things, the detail things. Now, we're going to
look at a bunch of things that will bring us four or five
horsepower, where in the past, we've been looking only at
things that can bring us 10 or more horsepower."
WITH THE TURBO AREA GOING AWAY
AFTER 2002, DOES THAT CHANGE HONDA'S AND TOYOTA'S APPROACH AS
WELL? "I think it will, actually. We all know that at the
end of the year, the engines will be done, come what may. So,
they don't need to look to the future with these engines,
either. Toyota will definitely be focusing on their 3.5 liter
motor, so that may re-direct some of their resources, possibly
at the expense of their CART engine. Honda, I guess, won't
have that program to worry about so I'd expect they'll put 100
percent behind their CART program. So, we're all in the same
boat, save for Toyota, who has to be working on their 3.5."
WHAT DO YOU SEE AS THE
STRENGTHS AND WEAKNESSES OF THE FORD-COSWORTH XF HEADING INTO
ITS FINAL SEASON? "Strengths start with the fact that it's
always been a powerful engine ... and hopefully will remain
the most powerful. Fuel economy was a real strength last
year, but that will be less of an issue this year. But
reliability is the key thing. (NOTE: XF failure rate during
races last year was four percent, lowest of the three
manufacturers) If I actually had to pick any one thing over
all the others, it would be reliability. If your engine is 50
less horsepower than anyone else's, but it always finishes,
that's probably better than having 50 extra horsepower and
failing even once in a season. Reliability is an enormous
issue for us, and the last few years we've focused on it very
strongly. So, even though we've put the engine speed up this
winter, we do it very cautiously. We say it may be 200 extra
revs in race trim, but until we come to the first race we may
decide to come back a bit on that, just for the reliability
point of view. So far, we've had a lot of success with the
engines we've run in testing, but we'd like to get more miles
on this spec of engine before we get to Mexico.
"Weakness, according to others,
has been our driveability. But, it's kind of like Italian
cars ...people say they always rust, and they did 20 years
ago, but then they fixed that problem 19 years ago. The
public has a very long memory. There's no question we had an
issue with driveability if you go back to 1998, 1998, or even
maybe 2000. But over the winter going into 2001 we made a
big step forward by working with Kenny (Brack) and Max (Papis)
when they were at Team Rahal, and we came a long, long way
there. So, our driveability made a big jump forward at that
point, and with less boost, it's become even less of an
issue. People may think we're down to the other two, but I
don't think there's much there, and our runs here this weekend
so far make it appear that there's not much there."
FROM AN ENGINEERING STANDPOINT,
ARE YOU SAD TO SEE THE TURBO ERA END, AND WHAT ARE THE
CHALLENGES OF THE NEW RULES CART WILL ANNOUNCE? "I think the
challenges are very similar between the turbo and a
normally-aspirated motor, to be honest. I guess the challenge
is always to make the most power, with the best economy, and
the best driveability, no matter what the package is. It's a
shame to see the turbo go, because we believe over the years
we've developed the best boost control of anybody's. We put
an enormous amount of work into that, so it's a shame to see
that disappear. CART's going to have a normally-aspirated,
rev-limited engine next year, and much has been made of the
fact that that's less technically challenging. But I guess I
firmly believe, and we've said all along, that the technical
challenge, and the cost, is completely driven by the level of
competition. If it's just one manufacturer involved next
year, it won't be very technically challenging. But if
there's two manufacturers, or three, or four, or five ... and
they all want to win ...it will be just as technically
challenging to make that engine work. If everyone is out
there, we'll all engineer it just to edge of failure, just the
way it is now, and that's the thing that makes it interesting
for an engineer. It's a challenge to engineer something to
the edge of failure, so that it will do its job, but no more.
So, the fact that it's normally-aspirated, and rev-limited,
doesn't make it less of a challenge, if there's competition."
--Ford--
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Martin Basso
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