2003 Engines: IRL vs CART

[CamKing]

Looking over the Press release about CART's 2003 engine rules, the thing that stood out the most is the 12k rev-limit. This one difference in rules will make it very costly to switch an engine over from the IRL's 10,700 limit to the CART 12,000 limit. The valve train on the IRL engines will not turn 12,000, so you would have to make new cams and springs to run 12,000. If you designed the valvetrain for 12,000 and tried to run it @ 10,700 it wouldn't make as much torque and HP as the valvetrain designed for 10,700. At 12,000 the engines Intake system will be required to move 80 more CFM of air, that will require a different port and intake design to optimize power at each RPM limit. I don't know if CART is going to limit the bore size to 3.661" like the IRL, but either way there will be problems. If they don't limit bore size, than they will increase the bore and cut the stroke to get the piston speed below 5,000fpm. This will require almost everything being changed to make the engine optimum for 12,000.
If they go with a 3.661" max bore like the IRL, then the piston speed will be over 5,000fpm @ 12,000rpm and require stronger and more expensive cranks, rods, and pistons.
Besides all this the engines will be required to handle 70 more HP @ 12,000 than they will @ 10,700 so some parts for the 12,000 limit will be heavier than the same parts for the 10,700 limit.

So, from what I see, I don't see much that will be common between the CART and IRL engines in 2003.

[Brickman]

Will the CART engines cost more? How much more?(+ -)

[CamKing]

Originally posted by Brickman:
<STRONG>Will the CART engines cost more? How much more?(+ -)</STRONG>

This is from CART's press release:
"the engines will be limited to an annual cost cap of $2.7 million for a season, including all racing and testing."

That is over twice as much as a good IRL engine deal.

[mario]

DO we know for sure what the IRL rev limit will be in 03?

[JoeBob]

Originally posted by mario:
<STRONG>DO we know for sure what the IRL rev limit will be in 03?</STRONG>

I wonder that too. Usually a new engine spec means a new rev-limit that gets racheted down as seasons go on to control speeds.

Also, will the CART engines be designed for peak power at 12k RPM if the rev-limit is 12k RPM? I thought I read somewhere that for the road courses the rev limit would have to be somewhat higher than the peak power, to ensure smooth shifting.

[Indianapolis500]

CamKing, question will the new CART engine be approved for the Indy 500, by adding a 10,700 rev limiter, or will the IRL reject it... what do you think..

[R_Mears_Fan]

It seems to me that the CART teams will only save on the costs of the tubs if they want to run one or two IRL races. Exactly how will this bridge the gap between CART and IRL?

[ZanardiFan]

My understanding is that these engines will be CART-only engines and not brought to Indy. For example, Toyota will make the IRL-spec engine to be raced in Indy. The CART teams using Toyotas in CART would use the Toyota IRL engine at Indy. The question is will the TWR variant for CART be badged Infiniti leading to a tie-in for Indy or will there be no connection between the two programs. If Judd builds a CART engine, they'll have to build a seperate engine for Indy and get it approved (probably after getting it badged by a manufacturer).

[Fueler]

Cam King... thanks... that kind of analysis is one of the reasons I hang out around here.

[Railbird]

CamKing

Thanks for the insight.

In your opinion, does the 12000rpm limit reflect what is needed for the street courses?

[Maslo]

It's an interesting point, but I don't know that the details are there to fully answer it. There are a lot of little details of this deal that either haven't been addressed or are not being made public yet.

My sense is that mechanically, you play by the IRL rules. Yeah, you may substitute a cam (et. al.) that's optimized for the higher revs, but within IRL limitations.

i.e. a CART-configured engine with IRL electronics would be legal in an IRL race but would probably not be the best choice. You could also try to take an IRL-configured engine and over-rev it in a CART race (again, probably not a good idea).

So cross-participation is probably only an option for those with the bucks. But in a relative sense, it's a heckuvalot easier than buying completely different cars as Penske and Gannassi have done. CART teams are looking at spending an average of $4M less per year, so that will buy a few Indy engines.

Likewise, an IRL team looking to run, say, Long Beach, would probably just buy a couple of engines (or just rent them).

I see as a bigger problem the matter of reconciling various testing and supply rules. Do CART teams violate the IRL testing limits by using too many Bridgestones in CART events? Does a crossover team from the IRL count in Toyota's total of cars they're supplying for CART?

[AdamM]

>>>>CART teams are looking at spending an average of $4M less per year, so that will buy a few Indy engines.<<<<

Maybe it saves Pac West and Sigma some money, but to the guys getting free engines and money right now from Honda and Ford it's looking like a pretty steep price increase.

[Jacoby]

Originally posted by R_Mears_Fan:
<STRONG>...Exactly how will this bridge the gap between CART and IRL?</STRONG>

I don't think it will. It helps the manufacturers, because common parts can be used in both series. I would be surprised if more than one or two IRL teams even attempt an effort to compete in a CART event. I still believe CART is in a world of hurt, and will still be too costly for the teams to race there AND Indy. In my opinion, we will see even more CART teams come to the IRL in 2003.

[jmart]

Posted by CamKing:
Looking over the Press release about CART's 2003 engine rules, the thing that stood out the most is the 12k rev-limit. This one difference in rules will make it very costly to switch an engine over from the IRL's 10,700 limit to the CART 12,000 limit. The valve train on the IRL engines will not turn 12,000, so you would have to make new cams and springs to run 12,000. If you designed the valvetrain for 12,000 and tried to run it @ 10,700 it wouldn't make as much torque and HP as the valvetrain designed for 10,700. At 12,000 the engines Intake system will be required to move 80 more CFM of air, that will require a different port and intake design to optimize power at each RPM limit. I don't know if CART is going to limit the bore size to 3.661" like the IRL, but either way there will be problems. If they don't limit bore size, than they will increase the bore and cut the stroke to get the piston speed below 5,000fpm. This will require almost everything being changed to make the engine optimum for 12,000.

If they go with a 3.661" max bore like the IRL, then the piston speed will be over 5,000fpm @ 12,000rpm and require stronger and more expensive cranks, rods, and pistons.
Besides all this the engines will be required to handle 70 more HP @ 12,000 than they will @ 10,700 so some parts for the 12,000 limit will be heavier than the same parts for the 10,700 limit.

Thanx for the analysis. Good stuff. A couple of questions though.

Your analysis is slanted toward the impacts when the engine runs at 12,000 and the resulting engineering issues. But since CART runs so many SC/RC, won't they need to develop a tractable engine that runs well across a much wider rev range, say maybe 6,000 - 12,000? If so, won't cam and port design need to be a compromise? It seems to me that in order to get power down lower than what the IRL formula currently offers, they would have to sacrifice top end power. So to gain it back, they spin it faster, but peak HP may not be all that different between the two designs (I'm assuming identical B/S ratios since IRL mandates max bore). Also, could the current valvetrain (or a slightly modified one) withstand brief bursts to 12,000 without undo wear? As I recall, the 2003 package will allow gear driven valvetrain rather than just chain -- does that simplify things at all? Finally, do you see either CART or the teams themselves maybe implementing a lower rev limit for ovals but utilizing the full 12,000 rev limit for RC/SC?

As I ask all of these questions, my assumption was that CART wanted to develop an IRL-legal motor so that all that was needed to cross over to Indy was to lower the revlimiter and maybe change over to an IRL-approved cylinder head. I assumed the bottom end design and B/S would be the same.

jmart

[ February 13, 2002: Message edited by: jmart ]

[arca]

Thanks Cam King,
this is what I am getting from your great technical post.

The CART 12,000 rpm rev limit MAY be smoke and mirrors advertising ploy.

You show that if CART keeps the same bore and stroke as the IRL, 12,000 rpm is not going to happen because of mechanical limits.

But yet CART could CLAIM that the engines turn UP TO 12,000rpm, even though they don't.

PS. what if CART allowed Titainium crank shafts and connecting rods, could the engine go to 12,000 rpm with the same IRL bore and stroke?