Varno

Sure its cool to say you have 900hp in a car, but if its all at 9000rpms whats the use? Since I definately plan on purchasing a RX-8 (blue) :D , I want to know, since I am not familiar with rotors, how to boost HP and TQ while lowering the RPMs? HELP!

Rich

If you're looking for low end torque, I believe that you'll be very disappointed in any rotary engined car. The use of having peak power at 9k is that it's more fun, and having peak torque so high results in more horsepower, as shown below:

HP = (Torque*RPM)/5252

The higher the torque curve, the more power. If you lower the torque curve, you lose horsepower.

Have you ever revved a car up to 9k? :D There's nothing better than revving an engine out. If you want something that runs out of steam at 3k, get a muscle car. Don't take that as criticism, I have nothing against 'em. Some people like V8s, and some people like rotaries. However, they're incredibly different, and you shouldn't try to get one to behave like the other.


This link does an exceptional job of explaining the reason that high RPM torque is MUCH better than low RPM torque:
http://www.vettenet.org/torquehp.html

Varno

Ok thanks.

wakeech

there is no absolute "better" for performance, either in the upper rev range or lower... it depends on how you want to drive... for americans of the die-hard muscle type, torquey is the only way to go ('cause they like to be able to light 'em up at 1500 rpm or whatever, with their 7.0 fricken' litre v8's... peices of crap). Anyway, if you want a sporty engine, as in motorsports like f1 or WRC or something big-buck like that (NASCAR is NOT big buck, and is just muscle car leftovers...) you want an engine that will give high speed acceleration (not just from a stop), and obviously as small and light as it can go. For this there is a simple solution: use a small engine and rev it to the moon... without the large displacement, the bottom end torque is crappy... but when applied very quickly at high rpm, the power can be awesome. so, that's why people into SPORTS cars (not muscle drag cars) are often inticed by the rotary... it's characteristics lend it to higher rpm's, and the combustion capacity (which is sort of a "replacement for displacement") allow it ungodly power for such a small volume and super light weight are a perfect fit for a sporty car...
now, i can't understand why you (Varno) would be so distressed about power in a particular part of the rev range... american cars just can't rev that high (horrible engineering... too much reciprocating mass) so they are geared to use their huge amounts of torque with very long gears, with a very short (?not sure if the right term?) final ratio, so you get a big increase in speed with a small increase in revs... to effectivly use the higher rpm power of the rotary (and it's superior torque curve... nice and flat) the final gear ratio could be far longer (?again unsure... i mean easier to drive... like a bigger gear on the rear tyre of a bicycle) covering more revs more quickly... the result in the end is the same remember... more gas burnt equals more go... doesn't really matter how you do it if all that matters is moving in a straight line...
but for cornering's sake, the lighter 13B evolution RENESIS is just plain better.

EVERYBODY!! CHECKOUT AND DONATE TO www.rotaryengineillustrated.com !!!!

Rich

wakeech, you didn't read the link, did you? High RPM torque is better for performance than low RPM torque. Imagine that you have 2 engines that have torque curves that are the same shape, just "stretched" differently. One has a redline of 5k, and a peak torque output of 250 lb. feet at 4k. The other has a redline of 10k and a peak torque value of 150 at 8k. The second is weaker, right? Wrong!
If you stick a gear on the output of the high RPM engine that reduces the rotational rate by a factor of 2, you will have an output shaft that can spin up to 5k (the 10k redline cut in half) and will have a peak torque output of 300 lb. feet (150*2) at 4k. Would anyone argue that 300 lb. feet at 4k is not "better" than 250 lb. feet at 4k, if the curves were shaped the same?


To qoute the cited site, "It is better to make torque at high rpm than at low rpm, because you can take advantage of *gearing*."

wakeech

no, i did read the link... what happens in a rotary and a muscle v8 are similar to "torque in the upper range", but "upper" for both engines is VERY different (the redline for an american v8, as you know, is middle of the range for the RENESIS)... so from a rotary's point of view, american v8's have more torque down low (around 4k to 5k) but the rotary's is around 6.5K or something (at least one with a wicked port on it, which in the upper ranges i suppose would perform something like a RENESIS)
but, both engines of a comparably sporty tune (wiht torque in teh upper ranges) the rotary's torque is way the hell up there, but i was saying there wasnt' anything wrong with it beign 4k higher, 'cause (as i see you copy pasted from the page!! ) you can take advantage of *gearing*

wakeech

no, i did read the link... what happens in a rotary and a muscle v8 are similar to "torque in the upper range", but "upper" for both engines is VERY different (the redline for an american v8, as you know, is middle of the range for the RENESIS)... so from a rotary's point of view, american v8's have more torque down low (around 4k to 5k) but the rotary's is around 6.5K or something (at least one with a wicked port on it, which in the upper ranges i suppose would perform something like a RENESIS)
but, both engines of a comparably sporty tune (wiht torque in teh upper ranges) the rotary's torque is way the hell up there, but i was saying there wasnt' anything wrong with it beign 4k higher, 'cause (as i see you've copy pasted from the page!! ) as you say: you can take advantage of *gearing*, which would result in similar (though not identical) performance, IF one isn't better than the other (in power)...