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CART & IRL - close, and yet so far.....


 by Mark Cipolloni
March 26, 2001

Go to our forums to discuss this article

There are a lot of rumors circulating that CART will soon abandon the 30 + year turbocharged engine heritage that Champ Cars have enjoyed and agree to a 3.5 liter normally aspirated engine formula so its drivers and manufacturers can get back to the Indy 500.  Will this mean we will see a unified Indy car series sometime soon, or just some CART teams running in the Indy 500 each year?  We examine what a common engine formula might really mean, and the implications of it.


As they exist today, the only real similarities between CART and the IRL are the weight of their cars (1,550 pounds) and their overall dimensions, which are nearly identical.  Other than that, and the fact they both include oval races on their schedule, they are as far apart as two racing series can get in terms of equipment, philosophy of how a series should be run, and types of tracks they race on.

Major Differences CART IRL
Circuits Ovals, road courses, street circuits Ovals only
Management philosophy Run by committee, car owner controlled.  Promotes ingenuity and diversity with fairly open rules.  USA roots, but competes worldwide in 8 different countries.  Prides itself on finding the best drivers, regardless of nationality, though some do get rides who bring money. Modeled after NASCAR - run by 'dictatorship.'  Stated goal is cost control.  Indy 500 is the focal point of the series, remainder of races play second fiddle.  A USA-only series that prefers American drivers, but due to lack of sponsorship, in many cases  has had to take on foreign drivers who bring money.
Cost of equipment Unlimited, but can't rise more than 10% per year Cost cap on chassis, engine, and transmissions
Cost to compete High due to level of competition, many races.  Minimum $10 million/car/year Low due to less races/ testing, cost/mi. about equal to CART.  Minimum $5 million/car/year
Car Weight 1525 Lbs, 1550 Lbs on high speed ovals 1550 Lbs
Engines 2.65L turbo about 875 HP, rpm unlimited 3.5L normally aspirated about 650 HP, rpm limited
Horsepower/Pound 0.573 HP/Lb 0.419 HP/Lb.
Engine ht., wt. dimensions Unrestricted, can be as small & light as you like Restricted minimums - large and heavy
Engine Availability By lease only from Ford, Honda or Toyota Available to buy for any IRL team that wants one
Engine Philosophy Like F1, may the best-design win. As long as the engine meets the rule book requirements you are free to improve/change anything at any time. Modeled after NASCAR, controlled to keep level playing field.  Must submit everything for approval, including things like new heads, intake, etc.
Transmissions Expensive Sequential/Transverse fwd rear axle Low-cost Sequential/Longitudinal behind rear axle
Aerodynamics Low downforce to slow cornering speeds Very high downforce to plant cars to track
Driver Salaries High $8 million/year (Andretti), average > $1 million/yr. High $2 million/year, most drivers race for a percentage of the race winnings only


Top - the Oldsmobile Aurora engine, the mainstay of the IRL, is some 30% larger and heavier than the CART Ford Cosworth XF engine below, but makes about 25% less power.

Given the above differences, it would be hard to imagine that CART and the IRL will ever become one series again.  However, with talk of some sort of common engine formula, there is hope that the two series can compete together at the Indy 500, and perhaps other selected events each year.  Unfortunately, even with a common baseline engine formula, there are still some very difficult hurdles to overcome that we will examine in more detail later.

New IRL and CART engines for 2003

According information posted on an IRL discussion forum by an Oldsmobile Aurora engine builder, "the IRL has finalized their new engine specifications for 2003, and it appears they have made some compromises to entice some or all of CART's engine manufactures to build an IRL engine.  

The new engine will be a normally aspirated 3.5L V8 incorporating a rev limiter. Major changes from the current 2001 engine include:

1. A decrease in the deck height from 8.10 inches to 7.486 inches.
2. Weight of the engine will drop from the current 320 lbs to 295 lbs (still very heavy by CART terms)
3. Crank centerline to bottom of sump will decrease from 4.5 inches to 4.0 inches.
4. The crank main size will increase from 50mm to 53mm and the rod pin diameter will increase from 40mm to 43mm.
5. There will be 2 fuel injectors per cylinder.

The IRL did not set a minimum crank weight for 2003.  The maximum bore for the 2003 IRL engine will be the same at 93mm.  This means it will be difficult to get significantly more RPM from the engine because the stroke of the piston will remain long. 

If you look closely at the relative location of each engines cam covers, it's evident that the CART Champ car engine (bottom) is very compact and sits much lower in the chassis than the current IRL engine.

The new GM engine design will be completed by the end of this year. It will be a completely new engine that will be tested during the 2002 season to work out any bugs before full competition in 2003.  All indications are that the engine will have the Chevrolet name on it."

CART has yet to announce their new engine formula, and the deadline for 2003 of March 1st (per their rulebook) has already past.  Under consideration are the 1.8 L turbo option, keeping their existing 2.65 L turbo engine for now, or adopting a 3.5 Liter normally aspirated engine with the hope that the engine manufacturers could provide engines for both series if they so choose.  The engine builders must get started immediately in order to have an all-new engine ready for 2003.

Although we don't endorse the concept, if CART goes to a 3.5L NA engine, it's not the end of the world for the many people in the CART community who feel CART engines should be closer in performance to F1 engines than IRL engines. As suggested by some folks in the racing industry, CART could probably use a block compatible with the IRL/Indy, but one or more parts of the rest of the engine could possibly be different: no rev-limits, different heads, cams, electronics, lighter weight (maybe they can add ballast for Indy) and other parts can ensure that they will still be powerful engines still capable of performing in the 13,000 to 15,000 rpm range needed for the street and road course events.  It's also possible that the CART version could be sealed leased versions, whereas the IRL version can be bought by anyone.

In order for the engine manufacturers to get more rpm from the IRL spec engine for CART, it may be possible for the engines blocks to have sleeves in them that would allow them to be bored out for the 'CART version' so the piston stroke could be shorter, by use of a different crank.

If CART retains the same block dimensions but opens up much of the rest of the spec (for their series) it's for the practical purpose of attracting other manufacturers who want a higher-tech type of racing engine... like Honda or Audi. CART is also going to need to open up the spec for their road races which require a wider rpm range instead of something that's tuned for ovals to run at a constant 10,500 to 10, 700 rpm.

Since CART has yet to figure out how to effectively deal with the dilemma of having too much HP on oval tracks and not enough HP on road and street circuits, perhaps they could use the 'IRL spec engines' (around 650 HP) for their oval races and the higher performing 'CART spec' engine (around 800 to 850 HP) everywhere else.  Since it is assumed that the engine manufacturers will be making both versions, it would not really matter which engine they drop into the chassis assuming both mate to the transmission used by CART (see transmission section below).  If the engine block is the same for both versions of the engines, there is no reason to believe this can't happen.

The $64 question - can the CART and IRL engines be similar enough so that a manufacturer could afford to produce engines for both series, yet different enough to meet the needs of each series?  If not, a manufacturer is going to have to choose which series they compete in, which is exactly where we are at today, isn't it?  However, engines are just one hurdle.

One other thing that needs to be remembered is that according to the IRL rules, any engine manufacturer that comes into the IRL must make their engine available to all of the teams. As we understand it, each automaker must have at least one channel of distribution for a complete, assembled, ready to race engine (including engine management system) for the specified price. They also must have a distribution channel for the same engine parts unassembled (for those who want to have another engine builder assemble and tune the engine) for a price somewhat below the assembled price (last I heard, about a $5000 discount).  They must be willing to sell either version to any bona fide IRL team who wishes to buy it. 

Therefore, will the CART engine manufacturers supply engines to the entire IRL field and still support CART too? Do they have that much money?  Honda for example, could be faced with supplying 75% to 100% of the IRL field (assuming their engine was the best) plus their existing CART teams.  In reality they would likely have to supply no more than 1/3 the IRL field because there would be 3 to 4 other manufacturers (Ford, Chevy, Nissan, Toyota)

We don't believe any of the CART engine manufacturers have the budget to supply and develop that many engines.  However, we are told that GM actually turns a slight profit selling its engines to IRL teams, so maybe there won't be any added expense to the CART engine manufacturers beyond the initial development costs and R&D (which are limited by the IRL) costs.  Once the manufacturer sells the engine to the team, it's up to the team to pay whatever engine builder they choose to rebuild and maintain them.

Transmissions are very different

The XTrac IRL transmission, above, hangs out past the rear axle centerline contributing to the complaint that the IRL cars are tail heavy.  Below, nothing hangs out the back of a Champ car, it's transmission sits forward of the rear axle centerline.

About the only similarities between a CART and IRL transmission is the fact that both are sequential shift units.  

The IRL transmission was designed to be a low cost unit.  Initially the unit was very large and heavy, which contributed to many broken driver backs.  When the cars would back into the walls, the rigid transmissions did not crumple and the deceleration forces were transmitted through the car to the driver.

This major deficiency was later corrected and the new transmissions are made to crumple better.  That, combined with the black impact attenuator (see picture at right) attached to the back of the transmission now provides a good crumple zone and back injuries have since pretty much gone away.

The IRL transmission is also designed exclusively for oval track racing.  It has no reverse gear and could never withstand the abuse a CART Champ car transmission must endure on street and road courses.

While an IRL transmission might see 2 to 4 gear changes per lap, depending on the track, a CART transmission undergoes as many as 80 gear changes per lap on some circuits.  In addition, the CART transmission must handle almost 250 more HP.

In the IRL everyone uses an IRL mandated transmission, whereas in CART the transmission is a unique design by each car manufacturer to maximize car performance.  In addition, a CART transmission case is made from light weight Magnesium, whereas the IRL unit is an aluminum case.  The differential on a Champ car is a limited slip unit.  On ovals they are fitted with a spool.  The IRL car runs a spool for all races.

In conclusion, even with a common engine formula, the transmissions in the IRL and Champ cars would continue to be very different.

The Chassis and Aerodynamics

Another major difference between CART and the IRL is the chassis.  The IRL chassis is visibly bulkier and the size of the sidepods mandated to be a minimum size to provide better side impact protection in the event of a side impact with a concrete wall, a common occurrence on oval tracks. 

Perhaps another reason why the IRL cars appear to be bulkier is the size of their high-downforce wings.  In general, the IRL cars run mandated large wings which provide a lot of downforce

The IRL car, left, has a somewhat bulkier appearance due to the larger engine.  The bodywork around a Champ car engine, right, is much tidier because the engines are much smaller in physical size.  Also, note the size of the rear wing on the IRL car.
Photo Credits: IRL car - Indy Racing League.  Champ Car - Mike Levitt/LAT courtesy of Barry Brooke Racing

Bottom Line

Unless the two series were to agree on identical chassis, engine and transmission specifications, the only thing interchangeable between the IRL and Champ car are the wheels.  Needless to say, if there is any thought of the two series running together at selected events, the CART teams are going to have to buy an entirely new car, different transmissions and, for the most part, a different engine.

That's what the CART teams have to do now in order to run IRL races, and vice-versa.  However, the whole purpose of the negotiations that are taking place now is for the CART engine manufacturers to supply engines for both CART and the IRL so when a CART driver runs in the Indy 500, he can do so with the same engine manufacturer as they run with in CART.  Currently they cannot.  Other than that, a common engine formula will put them no closer than they are today.

Potential Benefits

The Indy 500 once again becomes the Super Bowl of Indy Car racing - Assuming that the IRL and CART agree to coexist peacefully, and they agree on some sort of common engine formula, the Indy 500 can once again become the Super Bowl of Indy Car racing.  Although some may argue it already is, in reality the race has been significantly diminished because the more powerful CART teams do not compete.

If CART and the IRL were smart, they would create a fierce rivalry (as I suggested in this Hatfields vs. McCoys article) between the two series with the two sides fighting for bragging rights at the Indy 500 each May.  In fact, if both sides agree to promote the rivalry with an aggressive marketing campaign, and they don't race on the same days in the same TV time slot, TV ratings may actually go up for both.

What this means of course, is that the more wealthy CART teams will have to find about $3 million in additional sponsorship each May to purchase and run IRL equipment in the Indy 500.  However, as stated earlier, they will be able to do so with their CART engine manufacturers. 

The case for Indy Lights running IRL equipment made stronger  - As I have suggested on numerous occasions, the Indy Lights series should run with IRL spec equipment so the cars bought for the Indy 500 could be used in other races besides the 500, or sold to another Indy Lights team. Just like the NASCAR Winston Cup and the Busch series are run with similar equipment, but different variations of the same engine spec, so to can CART Champ cars and the Indy Lights series.

The Indy Lights series is struggling with low car count.  It is basically a series without a well defined niche.  It could use a shot in the arm.  We would like nothing better than to see the Indy Lights teams run with the IRL cars at selected events, and run as a support series to the Champ cars at other events.

More options for the manufacturers - With a common baseline engine formula, the potential will exist for someday having five or more engine manufacturers competing in both series.  Ford, Chevrolet, Honda, Toyota, Nissan, and possibly even Mercedes could someday build engines for both series.  However, as we stated above, whether they can afford to be involved in both CART and the IRL remains to be seen.

Potential Pitfalls for CART

25/8 Rule - The question on everyone's mind is what will Tony George do if a common engine platform brings a majority of CART teams back to the Indy 500 and they start to take the majority of the starting positions in the Indy 500.  There is a fear that Tony may reinstate the 25/8 rule again to protect the teams that have supported the IRL for so many years.  Alternately, he could choose to allow more than 33 cars start the Indy 500, something that is not without precedence as it has happened on more than one occasion, the latest back in 1996.

Loss of heritage and fans - A lot of hardcore CART fans bemoan the loss of their sacred turbocharged engines, a mainstay of the sport for almost 40 years.  Many of these fans feel CART should not go backwards in technology and HP, but instead stay their course by using the 1.8 liter turbocharged engine, an engine that will likely stand the test of time, just as the 2.65 L version did.  

CART could be left with a single engine manufacturer - To NASCAR's and the IRL's credit, they dictate what the engine rules shall be and it's up to the engine manufacturers to play by their rules.  However, in CART, because they have let the series weaken to the point of vulnerability, they are at the mercy of agreeing to whatever engine formula the majority of the engine manufacturers want. If CART's TV ratings were high, engine manufacturers would be knocking down their doors to build engines for the series. Instead, the manufacturers they do have are questioning the value they are getting.   That's not to say that they will get any more value out of an IRL program.  Their TV ratings are just as low, and, except for Indy, play to mostly empty grandstands.  For some reason, some of these manufacturers believe that one race, the Indy 500, that gives them publicity for just 2 or 3 weeks per year, is worth the huge investment of designing a new engine.  If they abandon CART, they are left with 13 USA-only IRL races for which to showcase their product.  Contrast that with CART which allows them to showcase their product in 21+ (soon to be 22 and more) races in 8 different countries.

At various times throughout Champ car history, one engine manufacturer has supplied the entire CART grid.  The IRL also had only one engine manufacturer (Left-over Ford Cosworth's the first year and Oldsmobile's the 2nd) when it first started.  CART could choose to go against the wishes of some and adopt the 1.8 liter turbo formula, which is probably a better choice for the long haul.  The risk of course is only Honda may be left to supply engines to CART and one has to question whether they are willing to supply the entire field. They are strongly in favor of the 1.8L formula.   Alternately, CART can try to get Audi to supply engines too since they already have experience building turbocharged engines for their highly successful ALMS R8 Audi (the R8 runs a somewhat similar 3.6 liter V8, turbocharged, 90 degree cylinder angle, 4 valves per cylinder, 2 Garrett turbochargers, 2 32.4 mm air restrictors and boost restriction to 1.67 bars absolute).  That would give CART two manufactures.  Ultimately it is in CART's best interest to mandate what it feels is the best engine formula to secure its future.  As long as there is rules stability and they can grow the TV ratings, engine manufacturers will likely be willing to play.

CART could eventually be forced to adopt the IRL rules completely - The possibility exists that CART will adopt the 3.5 liter NA formula and initially the engine manufacturers will supply engines to both series.  However, if the economy stays flat for an extended period and the manufacturers begin budget cutting to offset car sales losses, the engine manufacturers might have to choose to do either the CART or the IRL program, and since they will be spending less on the IRL program, they may choose to drop their CART program.  Then CART teams would be faced with buying the IRL spec engines lock, stock and barrel, for all their races, and that's assuming the supply is adequate for both series.


All in all, CART has a difficult decision to make.   They can choose to go along with the majority of the engine manufacturers wishes and, as we understand it, adopt a normally aspirated engine with the hope that CART and the IRL can coexist in harmony forever (not withstanding a nice rivalry).  Alternately they can choose to stand their ground, stick with their traditional turbocharged engines and hope enough engine manufacturers support them to make it through a tough period.  The last decision, and perhaps the best one for another year, is to do nothing, and give themselves and their engine manufacturers more time to study the implications of this very important decision.

All is not doom and gloom, however, as CART has many successful events on its calendar, is gaining in popularity around the world, has many strong teams, the movie DRIVEN is about to be released, and we hear a new TV contract is close at hand.  If CART can show the manufacturers that they are turning the ship around by years end, perhaps the decision on which way to go with the engines won't be as difficult.

If CART moves to a 3.5L normally aspirated engine, it will move them a little closer to the IRL, but the two series are still a long way from doing business as one series under a common umbrella, and without that, the fan confusion between the two will likely remain.  CART & IRL, close, and yet so far.....

The author can be contacted at markc@autoracing1.com

Go to our forums to discuss this article


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