The RX8 Torque
 

I have a question concerning the RX8 Torque. We know that the Torque in the RX8 is kind of low. So any car with a higher torque will launch faster and will have an advantage over the RX8??? ?

Thanks

Here is a really good article which addresses this subject. The gearing is a big factor. But suffice it to say...

"Horsepower is the determining factor in the rate of acceleration of any vehicle"

http://www.yawpower.com/tqvshp.html

It’s not that easy, a Diesel F-350 has over 3X the torque a RX-8 has and will not blow away anything. Higher torque gets objects moving from a standstill faster than lower torque but after that horsepower takes over.

Actually, horsepower is really what counts. Torque will get you off the line... Example, the first step in a race. Here are the calculations:

horsepower = torque * 5252 / RPM
Torque= (5252 x HP)/RPM

In this case we can say the RX8 makes 238 hp (let's just use Mazda's numbers) at 8250 RPM. That means T = (5252 x 238) / 8250 rpm which = 151 ft/lbs of torque.

I just wanted to add... Torque is important becuase the more torque you have the better you will perform at lower RPMs. This is why people say the RX8 is a "dog" until you hit 4,000 rpms.

I've seen ford Diesel's running 12 second 1/4 miles... ;)

Gearing is the great equalizer. Because of the low torque, the RX8 is aggressively geared to help compensate. :)

Gearing and low power-to-weight ratio get you up to speed quick, torque helps build on that inertia to pull you along even faster.

Look at the 80 - 120km/h comparison with the alpha here. That is torque my son. There is no set equation though, more torque doesn't just mean more acceleration or more top speed. A number of factors (as discussed above) come into play.

https://www.rx8club.com/showthread.p...ighlight=alpha

Umm no pretty much everyone is a little off. Horsepower is torque * RPM / 5252. HP will always be lower than torque before 5252 RPMS. If your car makes more torque at a given RPM it has more HP at that RPM therefore will accelerate faster at that RPM given same gearing, however the RX-8 is designed to flow air well at higher RPM's, so it can maintain its torque all the way up to 9000RPM, where as in say the diesel motor, maybe it is making 800lb ft of torque, but the engine is designed so that after 2800RPM the torque drastically drops off. If your making 800LB ft of torque at 2800RPM you are making 426HP. With proper gearing, thats not too slow. However if you are making 300 torque at 9000RPM you are making 514HP. By changing the gearing, you can keep the RPMs in your peak power area.

http://www.yawpower.com/tqvshp.html

HP is what moves you torque takes over yadda yadda is just generalizations. Gearing, HP, Torque, and Mass all affect acceleration. Torque is most important to me because it is the best thing to change to accelerate faster with the car you have. Modifying the car so torque is higher soon and all across the powerband especially in the higher RPM's is going to increase HP all across the powerband which will make the car faster. This is why you can lose torque at the peak, but increase the torque after the peak, which will increase your HP. This is also why you can have a higher peak torque than HP.

LOL... as you can see, I did my calculations right, I just misstyped the equation. Yes, It's HP = torque * RPM / 5252.

To get back to the original poster's question, compare two cars with similar overall performance - one gets it's power from revs, the other, from displacement (i.e., torque). Say, an RX-8 vs. a G35. The car with the torquey motor will easily pull the car with the revvy motor from a stand-still, unless the driver of the revvy motor is willing to resort to drop-clutch starts, and even then it's questionable.

But peak performance (once the cars are in motion) is more of a power-to-weight ratio question, assuming both cars are geared and driven properly.

just a question about 1st gear , my 8 doesn't seem to like first gear much. is it supposed to be real loud starting and rough from 3000rpm? b/c every other gear is real smooth n quiet upto upto atleast 4500 and not rough at all

Doesn't sound right to me. You might want to start a new thread if you want to get other's feedback.

A lot of variables go into 0-60FT times. How do you get a fast 0-60ft time? Tire pressure, tire grip, torque, suspension, type of differential.

Given all the other conditions are the same, a motor with more torque is going to be faster at a given RPM until the car with torque at higher RPM starts making more HP. Comparison: Car 1 with 250lb ft of torque at 3000RPM, power drops off at 6000RPM, Car 2 has 150lb ft of torque at 3000RPM, power drops off at 9000RPM. just for comparison the torque stays constant throughout the RPM until power drops off. At 3000RPM the first motor is making 142HP 2nd motor is making 85HP. 6000RPM the 1st motor is making 285HP, the 2nd motor is making 171 HP. So far all the way up until 6000RPM the first motor has been creating greater HP. Now 9000RPM the 2nd motor is making 257HP. Almost as much as the motor that was making more torque was making at 6000RPM. Now with the way the cars would be geared, our shift points would probably keep the first motor going from 3800-6000RPM each shift and the 2nd motor 6000-9000RPM each shift. If you launch the cars from idle, obviously the first motor will be making more power all the way up until the other motor reaches 6000RPM. This is why people consider high torque motors to launch faster off the line and why you have to launch high RPM motors already at high RPM, so that when you take off your motor is already at 4000RPM so its making a lot more HP then it would be at say 1000RPM. The RX-8's advantage despite its less torque is its lighter weight than many of its competitors.

Hopefully that makes a little more sense to you as to why it is "easier" or faster to from a standing start with a high torque motor and why a high RPM motor can still be fast.

If the article by Paul Yaw is a little over your head, try this one from www.modulardepot.com

http://www.modulardepot.com/?show=articlesdet&aid=44

and

http://www.modulardepot.com/?show=articlesdet&aid=46

The number one thing that gets people confused is mixing up torque at the rear wheels with torque at the crank. Gearing can create enough rear wheel torque to move mountains, but the price you pay is speed (rpm's). Or vice-versa. You can gear a Miata to have the same rear wheel torque as a viper does, but then you will be redlining first gear at 3mph while the viper keeps on pulling. So unless you're running a race to see who gets the farthest in .1 seconds, you have to look at horsepower* to compare engines.

People say the RX-8 needs more torque to accelerate better. But torque is only one half of the HP equation**. If you could make the same 138 ft.-lbs but raise the RPM to 15,000 RPM's...that would be nearly 400 HP, and the car would be a quarter-mile terror just as surely as if you had increased torque to 230 ft.-lbs. Of course it would be much, much cheaper and practical to increase torque (see rotarygod's post about what would be involved in raising the max RPM limit on the Renesis).



* This is aside from peak HP versus average HP discussions, which is a whole different thread, heh.

**Pet peeve: "Torque is more important than HP, dynos only measure torque"--umm no, dynos measure both torque and RPM's. :)

Yes, but no... Torque is only one half of the equation, but if you had the obility to turn higher RPMs you would be past "the curve". For example reving the car to 9500 rpms is not going to help you accelerate any faster. As was posted earlier, once you cross the 5252 RPM line your torque must increase in order for your HP to increase. Correct me if I'm wrong, but here's what I say:

151 lbs/ft * 8250RPM / 5252 = 237 hp (What we supposedly have now)

If you were able to increase the RPMs but not the torque, here is what you would have:

First, the torque will drop tremendously to say 100 lbs/ft (VERY optimistic)
100 lbs/ft * 12000 RPM / 5252 = 228 hp.

Anyway, I could be completely wrong so someone please correct me if I am. But, the bottom line: There are too many variables that take place in a straight line race. You can't just look at one or two things but all: HP, RPM, Torque (all in the same family), gearing, weight of vehicle, and of course traction or you aren't going anywhere...

Thismight be a bad example but in a real life situation where youd want tohave a car w/lots of torque are cases where you are stuck in a slowmoving lane of traffic (going below 8 mph) andneed to get into the faster moving lane (going over 30) maybe to say - tomake the green light. Itd be less dangerous topull off that manuever in a car w/lots of torque b/c youll have enough instant power to match the speed of the other oncoming cars w/lower risk of them ramming youwhen you switch into their lane.

Errr...I think it's 138 ft.-lbs. @ 9100 RPMs. "In theory", which would be right at 238 HP. In reality, you can feel it go flat starting around 6,000, thus what some (Canzoomer, others) have said is actually more like 220 or so. :( I guess I'm talking about what the renesis should be doing--a fairly flat 138 all the way to redline. In my (admittedly hypothetical) example, the torque remains constant and the RPM limit is increased, so HP would increase as well. So basically we can:

A) Keep making the same torque but at even higher RPM's
B) Make more torque but at the same RPM range
C) Some of both

Any of these will increase the HP (and acceleration) of the car. Assuming that each option is geared properly of course.

A Lotus Elise wouldn't have any trouble, and that's a no-torque car. Likewise for a sport bike. I would, however, hesitate to perform that manuver in a typical diesel pickup. Remember, low torque at the crank does not necessarily mean low torque at the wheels. (Also we have to consider throttle response, which is an entirely separate issue. You can have gobs of power but crap throttle response from overly heavy rotational mass, or from the nature of the engine itself, like turbines.)

A car that makes it's HP via big torque might be easier to drive in this situation though...just mash the gas and go, with no need to build revs and play around with the clutch first.

Seems that "Torque" is a big part of the quest for more forward displacement. It looks a bit like the difference between the four strokes and two strokes bikes.
The 2 stroke will jump ahead and keep the lead for sometime until the 4 stroke develops speed and catches him. With the RX8 is like having so,so initial starting speed and then it will mount to a decent speed as a combination of HP and Torque.

Thanks

Vinnie

The 8's torque is not that bad at all, especially by rotary standards. Unfortunately it's average weight of 3000 lbs is stetching the envelope. Mazda needs to never use a normally aspirated 13B in anything as portly as this again. If the car were lighter it wouldn't need the gearing that is currently being used (4.4) and the fuel economy would improve also.

Post Deleted: Street Racing - 7 Day Ban per RX8Club Rules
if i may add to this im not boosted stock air box obx header and ap dual resonated midpipe...only upgrades so far and trucks keep next to me but once i get to the top of third i start to leave them i have even had a diesel hauling ass and loud as all get out next to me once i got to 7000 rpms i started to pull rx8s high points are the revs stay in higher revs better you are....for example i raced a built h22 honda hatch he has an intake exhauust pulleys and ignition upgrades. if you stomp the pedal to the ground and slam to second and higher it may not be good for the tranny....but for some reason its helped keep up kind with the s2000 before i had trouble but now doing what i do when i race or mess around i keep up the h22 was neck and neck with me after i started to do this i was leaving him but when you shift dont let go of the gas and shift FAST! if not have fun grinding best of luck =)

Thread closed.

BlackRX8GT your street racing post has been referred to the admins for action. We do not tolerate posts discussing it.