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The graphs are pretty clear that the Rotax not only has more than a 1 hp advantage, but it also has more than an extra foot pound of torque and a much broader HP / torque curve. From the data it has a good 5-8% advantage over a Leopard so why does it get to race at the same weight? :idn:
Make sure yo check out the rpms as well. The main reason the Rotax is at a disadvantage to the leopard at some tracks is because some tracks require a broader RPM range then the Rotax has avaliable.
The Rotax at our elevation will only go to around 13,500, where with my leopard at Greeley I was at almost 17,000.
New guy here again 😆
I read the weights list and a few questions.
1. is this for CSC :idn:
2. where is Arrow chassis :idn:Any and all replies r appreciated 😀
The CSC uses TAGUSA weights for the different TAG engines. It does not matter what chassis brand you use for your TAG engines. Most karts are not like motorcycles that come with an engine included.
Now the rpm answer is really confusing from an engineering perspective.
If you look at the “power band” of both engines, the rotax has a nice broad power band and since it is at lower rpms it can be geared to take advantage of this.
If rpm were more important than HP, then those low rpm 4 cycles that produce around 34 HP would be getting trounced by Leopards which is not the case. If these graph were run at sea level at 29.92 inches of mercury (barometric pressue) then at 17,000 rpm you would only have 14 HP or less in Colorado due to density altitude factors. Temps above 60 degrees would provide even less HP.
It does seem that the gearing is a bit more critical with the rotax, especially on courses that have a big mix of technical turns and long straights. It also seems that the HP loss near the exhaust valve transition causes a problem.
So are the weight difference established at sea level, as this relative differences in HP are more pronounced at altitude?
Well, I’m sure someone can explain it better than me, but I’ll do my best.
The Leopard, with the ability to rev higher, allows you to gear for real slow corners (like what Bandi has) so that you come off of them in the middle of the power band. You can gear it to give you maximum power off the corner then just over rev it down the straight.
The Rotax, having that limited rpm range, does not allow you to come off the slow corners in the power. At Bandimere especially the Rotax will be so low in the rpm’s it wont pick up until you are well out of the corner, then when it picks up it does accelerate hard but the leopard has already been going for a while. The difference is so great that the leopard is already long gone.
Now, Tagusa weights are set up for most tracks around the country, and most tracks are tighter than the ones we have here.
In state the leopard has the advantage at Bandi, the rotax the advantage at IMI, while as our other two tracks are even. This is a good mix to allow for both engines. And even at the weights we have been using, remember a leopard won the majority of races last year, with a Rotax only winning IMI.
Like I said I know someone else can explain it better, but I’m doing my best.
Greg
The Motori 7 seems to work at all Colorado tracks. And should even be better for this comming year, now that we can use the head it was built with.
We have also started running our Motori 7 JR motor, and will be offering it as soon as Kartworks finishes its testing process. Look for this motor to jump to the top in JR TAG. It’s FAST…..
Motori 7 IS CSC state champion in Masters and SR for 2006.
The range of usable power is whats important. At some track, the range required is not that critical. For example, at IMI, we only need about 3 to 4,000 rpm range. We turn our Rotax no more than 12,500 and do not go below 8,000. In that range, the rotax is hard to beat. However, at a track like Bandimere, we are at 6,000 off the slow corners and yet we top out long before the end of the straight. Those motors that have a wider power band, can easily beat the snot out of the Rotax there.
At Grand Junction, its just about a draw. At the current weights and power band demands, its about a dead heat. No engine has a clear advantage that I can see. I’m not sure about The Track. At first glance, I thought it would be all Leopard, again due to power band requirements. Now I’m not so sure. It may turn out that up hill, advantage Rotax, down hill, advantage Leopard.
Understand.
Of course gearing makes a big difference so it seems that on a tight course with a lot of sharp turns the broader low band of the Leopard works better while the Rotax gets bogged down with that bump at the low end where the exhaust valve kicks in. More open course and the Rotax HP gets the advantage.
Makes sense the Motori would do better as it womps on both the Leopard and rotax on both HP and Torque according to the graphs.
It appears that in 06 the Motir ran at the same weights but now for 07 they’ve added 10 pounds for the Motori to equalize things a bit.
What guys in Tag should understand, if they are looking for an advantage through the motor, they are looking in the wrong spot. If a motor dominates, it will get more weight added to it to balance things out. They also need to understand that certain motors will have advantages because of the power band requirements. At some tracks, some engines will do better than the others. Where you race could be a big factor in the decision.
High hp motors run at higher weights. So drivers who can not meet the weight limits of a certain motor should look at the heavier motors. A lighter driver should look at the lighter weight motors.
Other considerations, some engines have better local support or last longer between rebuilds. Price, some are cheaper than others. Do you want to work on it or leave it to a service center? All of these considerations are more important than raw hp numbers.
@jj wrote:
It appears that in 06 the Motir ran at the same weights but now for 07 they’ve added 10 pounds for the Motori to equalize things a bit.
Yup, I’m not eating as much tuna and skinless chicken in 2007 and I’ve gotten reacquainted with an old friend of mine a lot this holiday. Say hello to Mr. Pumkin pie and Mr. Eggnog! 😀
I talked with Marty Casey of TAGUSA about the Biland and Rotax weight changes and he states there was a mistake made on the web site and the weights have not changed from last year. He also said that he knows there will be a problem with the Motori head at high altitudes and they are working on a comprise so that it will not have too much of a power advantage.
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