ChrisB
02-28-03, 09:33 PM
It looks like a Champ V-10 might be on it's way. Some stuff to consider...
1. Orifice restrictor for ovals?
We know that ovals and road-circuits have different Hp requirements. For an oval, it's now generally accepted that 700Hp is about the right number. But a Champ V10 will supposedly do 750hp. Currently with the turbo they're running a higher boost to make 750hp for roads and less boost for 700hp for ovals. With an NA V10, would they run some kind of "sharp-edged orifice" restrictor to bring the Hp down to 700 for the ovals?
2. Hopefully 3.5L
Pook has said that a Champ V10 is not going to be the same as the engines used in F1. In other words, they won't be interchangeable/compatible. This means it doesn't HAVE to be 3.0L. The rumor is that it may be 3.5L. That's good... it might be tough to make 750hp@13k rpm with only 3.0L, but it's more do-able with 3.5L. They could always use an orifice restrictor to bring it back down to 700hp for the occasional oval.
3. Tight dimension specs
It looks like this engine is gonna be a V10 version of the Cosworth XG 3.5L V8 announced last year (before the XFE turbo deal) which in itself was an NA derivative of the XF turbo. The XG V8 was intended to be pretty close to the IRL 3.5L V8, with lots of dimension restrictions but a little more rpm & power. I'm OK with Nascar/IRL-style engine dimension restrictions as long as they're close to optimal. Tight dimension specs is what woulda made high-boost-roads/low-boost-ovals possible without the manufacturers making a different engine for each (beyond a spec engine series). It'll also be applicable for running an orifice-restricted engine on ovals.
4. Say no to airboxes.
CART shouldn't lose the sleek look we all like about the Champcars, and put a big hump at the back of the cars profile. Nascar and Indy Lights (and early F1) have shown that a race engine can run just fine without the intake air being "rammed". Think about it... the airbox is most effective at high speeds like you would see on an oval... which is where they might be using an orifice restrictor. Why use a device to increase power only to need to take it away? The airbox is least effective on a road-course, paricularly braking and accelerating in turns when the speeds are lowest. There's no advantage to having an airbox if everyone also has one... it's a wash. There's also issues of whether airboxes disturbs the airflow to the rear wing. Tech reasons aside, aesthtics and differentiation are important too. Champcars, even with an NA engine, don't need airboxes. (Of course, if CART were to go to a spec chassis, they could make the intake opening over the engine whatever they want, and everyone would have the same thing)
5. V8 vs V10 sound frequency.
The equation to get the engine exhaust frequency: hz = rpm/(60/(cyl/2))
So here's a couple V8 vs V10 numbers...
v8 10.4k rpm = 693hz (IRL 2003)
v8 12k = 800 (CART 2003)
v10 12k = 1000 (for comparison)
v8 15k = 1000 (CART 2002)
v10 13k = 1083 (Pook said 13k)
v10 18k = 1500 (F1)
As we see by the 12k rpm numbers, by having 2 more cylinders, the V10 is 20% higher given the same rpm. If they run it at 13k it's still a slightly higher pitch than the 2002 V8's. Fine with me. But in order to somewhat match the turbos muffled "whoosh" sound, they should probably consider...
6. Full time high-flow mufflers.
With a V10, they're probably going to have to run mufflers on the street circuits. Therefore, they should consider using them full time for performance consistancy. A muffler doesn't have to be drastic... just enough to bring the decibels down to about what they are now with the turbos. High-flow mufflers can be tuned to sound pretty good too.
1. Orifice restrictor for ovals?
We know that ovals and road-circuits have different Hp requirements. For an oval, it's now generally accepted that 700Hp is about the right number. But a Champ V10 will supposedly do 750hp. Currently with the turbo they're running a higher boost to make 750hp for roads and less boost for 700hp for ovals. With an NA V10, would they run some kind of "sharp-edged orifice" restrictor to bring the Hp down to 700 for the ovals?
2. Hopefully 3.5L
Pook has said that a Champ V10 is not going to be the same as the engines used in F1. In other words, they won't be interchangeable/compatible. This means it doesn't HAVE to be 3.0L. The rumor is that it may be 3.5L. That's good... it might be tough to make 750hp@13k rpm with only 3.0L, but it's more do-able with 3.5L. They could always use an orifice restrictor to bring it back down to 700hp for the occasional oval.
3. Tight dimension specs
It looks like this engine is gonna be a V10 version of the Cosworth XG 3.5L V8 announced last year (before the XFE turbo deal) which in itself was an NA derivative of the XF turbo. The XG V8 was intended to be pretty close to the IRL 3.5L V8, with lots of dimension restrictions but a little more rpm & power. I'm OK with Nascar/IRL-style engine dimension restrictions as long as they're close to optimal. Tight dimension specs is what woulda made high-boost-roads/low-boost-ovals possible without the manufacturers making a different engine for each (beyond a spec engine series). It'll also be applicable for running an orifice-restricted engine on ovals.
4. Say no to airboxes.
CART shouldn't lose the sleek look we all like about the Champcars, and put a big hump at the back of the cars profile. Nascar and Indy Lights (and early F1) have shown that a race engine can run just fine without the intake air being "rammed". Think about it... the airbox is most effective at high speeds like you would see on an oval... which is where they might be using an orifice restrictor. Why use a device to increase power only to need to take it away? The airbox is least effective on a road-course, paricularly braking and accelerating in turns when the speeds are lowest. There's no advantage to having an airbox if everyone also has one... it's a wash. There's also issues of whether airboxes disturbs the airflow to the rear wing. Tech reasons aside, aesthtics and differentiation are important too. Champcars, even with an NA engine, don't need airboxes. (Of course, if CART were to go to a spec chassis, they could make the intake opening over the engine whatever they want, and everyone would have the same thing)
5. V8 vs V10 sound frequency.
The equation to get the engine exhaust frequency: hz = rpm/(60/(cyl/2))
So here's a couple V8 vs V10 numbers...
v8 10.4k rpm = 693hz (IRL 2003)
v8 12k = 800 (CART 2003)
v10 12k = 1000 (for comparison)
v8 15k = 1000 (CART 2002)
v10 13k = 1083 (Pook said 13k)
v10 18k = 1500 (F1)
As we see by the 12k rpm numbers, by having 2 more cylinders, the V10 is 20% higher given the same rpm. If they run it at 13k it's still a slightly higher pitch than the 2002 V8's. Fine with me. But in order to somewhat match the turbos muffled "whoosh" sound, they should probably consider...
6. Full time high-flow mufflers.
With a V10, they're probably going to have to run mufflers on the street circuits. Therefore, they should consider using them full time for performance consistancy. A muffler doesn't have to be drastic... just enough to bring the decibels down to about what they are now with the turbos. High-flow mufflers can be tuned to sound pretty good too.