RPM VS HP

[BADGER]

What are the main factors that determine what rpm creates maximum hp? I know the equation is hp=(torquexrpm)/5252 so I know that creates a bias for high rpms, but why would an IRL engine not make maximum hp right at the maximum rpm. In F1, I realize there are greater frictional losses and probably combustion inefficiencies that crop up, but the IRL has rpm limits so much lower, I wonder why building for maximum hp would not yield an engine that produces it at 10700?

[CamKing]

The cam duration determines at what RPM an engine will make Max HP. in determining what RPM to design the cam for, we look at what the RPM range of the engine will be. We design the cam to make the most power throughout the rpm range of the engine. This usually makes peak HP about 400 rpm below peak RPM. If we designed the cam to make peak power at peak RPM, then the engine wouldn't make enough power coming off the corners.

[guido]

What is the actual Revband at Fontana and Texas compaired to Kansas and St.Louis that is actually used. Do you think there will be several sets of cam,intake,and exhaust combinations used at different tracks next year?

[anythingbut monstertrucks]

Originally posted by guido:
<STRONG>What is the actual Revband at Fontana and Texas compaired to Kansas and St.Louis that is actually used. Do you think there will be several sets of cam,intake,and exhaust combinations used at different tracks next year?</STRONG>

I heard from a mechanic in the paddock of the IRL race at Nazareth, that the gear ratio selection is the most important variable for IRL cars. I think power off the corner does not appear to be an important factor on the "flat out" IRL tracks.

[dog-ring]

Originally posted by anythingbut monstertrucks:
<STRONG>

I heard from a mechanic in the paddock of the IRL race at Nazareth, that the gear ratio selection is the most important variable for IRL cars. I think power off the corner does not appear to be an important factor on the "flat out" IRL tracks.</STRONG>

Power off the corner is important at 1.5 mile ovals as the engines can lose quite a bit of revs in the corners. The engines that get back up to the limit quickest are usually the ones that are running at the front

[BADGER]

Originally posted by CamKing:
<STRONG> This usually makes peak HP about 400 rpm below peak RPM. If we designed the cam to make peak power at peak RPM, then the engine wouldn't make enough power coming off the corners.</STRONG>

It is the above that seems kind of backwards to me. It seems the engine and its components are designed to reach peak hp slightly below max rpm. Why wouldn't it be designed to make the absolute most hp that can be generated, even if it ends up at max rpms? It seems like in theory, that would work as long as the engine doesn't drop out of its powerband. As an example, lets assume next years engines were carried over to next season. I believe they are at 10700 now, and lets use 10300 as the rev limit for next year. If the current engines make peak hp at 10300, would there be an effort to redesign them to make peak hp at a lower rev, even if peak hp went down? To further illustrate:
Engine A
650hp @ 9000 rpm
665hp @ 9500 rpm
695hp @ 9900 rpm
675hp @ 10300 rpm

Engine B
615hp @ 9000 rpm
650hp @ 9500 rpm
695p @ 9900 rpm
705hp @ 10300 rpm

Now assuming a track with little rpm change, wouldn't engine B be the better engine if full throttle was the norm? I realize that engine B never seems to exist, yet if you have little rpm change and want max hp, it would seem to be the better choice. On a street car, I believe the drop off is due to tradeoffs at lower revs for more torque and to prevent over revs, and in f1, it is likely due to increased friction which goes up by a square (cube?). Is there other reasons why engine B likely does not exist?

[CamKing]

Engine B doesn't exist in any form of racing because it would get it's aZZ blown off by engine A. Engine B may make more power at 10,300, but the lack of power at the lower RPMs will cause the engine to take longer to get to 10,300. The engine that accelerates from the middle of the corner to the flagstand quicker will always win. acceleration is the key. F1 engines make peak power close to 1,000rpm below peak RPM, so they can accelerate faster off the corners while shifting through the gears.

[jmart]

Posted by Guido:
Do you think there will be several sets of cam,intake,and exhaust combinations used at different tracks next year?

As I understand it, heads (including intake/exhaust port shapes and dimensions) are in the "closed" development area and must be run as is -- no porting/polishing allowed. Assuming that's still the case, the question then becomes, "Will manufacturers design several different style heads and will the IRL approve each of them?"

I seriously doubt if it would get to that, at least I doubt if the IRL would approve them. Last year, Chevy (maybe through Speedway, I'm not sure) designed a different intake manifold/runner system which slightly raised the power peak, but more importantly flattened it out across a wider rpm range which proved to be better than the stock system. Manifolds and cams are in the "open" area and individual builders can try to make a better system. But even so, I don't think they had tailored manifolds for each track. Maybe cams, need to ask CK on that one.

If I've said anything wrong anyone, please chime in and correct me.

jmart