Who cares, live, drive shift!

 

With the MREV-2 + 5/16" spacer combo, especially once its tuned, you lose very little if any top-end and gain a lot of mid-range. That is great not just for daily driving but for auto-xing and tracking as well!

 

Lots of torque on its own and ho HP is bad, and lots of HP on its own with no Torque is bad. The Z is at a good level in that department, perhaps a "little" short on torque. Personally, I will take both.

As for Albertos point, I am going with the 3500-5500 RPM choice. The redline on my car (no Rev Up) is 6600 (or is it 6500, 6700, can't remeber exactly), which is only a few hundred above 6200. At 6200 my foot is headed towards the clutch pedal. I don't really need power there.

 

HP = torque X RPM/5252

If you've got torque, you've got HP. Just look at the formula.

 

Your equation is missing one crucial element.

 

That link is the most thorough and accurate article that I have read so far.

 

Peak tq at low rpm. The formula is (tq x rpm)/5252. 600 ft/lbs at say 2000 rpm = only roughly 229 hp.

edit to add: damn, I should read the whole thread before posting. Aftermath_Z's linked thread tells you the same thing I said.

 

Well, yes, it was missing a factor, so I edited it in.

But with or without the 5252 divisor, HP rises in direct proportion to torque.More torque, more HP.

And since peak HP occurs at the point where the torque curve is declining faster thatn RPM increases, the only way to increase peak HP is to increase torque.

bill

 

HP can rise even if torque doesn't. HP can rise even if torque is dropping. It's not directly proportional. If that were the case the hp/tq plots would look exactly the same.

Edit... I think you meant to say direct relation... big difference.

 

so back on topic why would you pick a Rev-up vs. a Non-Rev-up if we all like tq, better then hp?

 

Well, I guess I don't understand the difference between "direct" and "proportional", so let me restate...

At any point along the RPM axis, an increase of 5% in torque will yeild a 5% increase in HP, an increase of 10% will yeild an increase of 10% in HP, etc.

To me that is both a "direct" and "proportional" relationship.

And the reason all power curves do NOT look alike is because the shape of the torque curve varies dramatically from one engine type to another.

 

I answered that on the first page:

Well, since I do about 95% of my driving in the midrange, it seems like a pretty simple choice to me. I want the power in the range that I most use.

And that's really the answer to the original question. Most drivers (whether you drive aggrssively or more normally) prefer to have the strong part of the power band in the range that is most used for daily driving.

bill

 

Thanks for your highly technical explanation!

 

I owned a '91MR2 turbo for 7 years, bone stock except for a boost controller that allowed me to up the boost from the OEM setting of ~ 11 psi to 15 psi.

The OEM turbo (CT26) on the MR2 was a small twin-scroll design tht was vary responsive ( almost zero lag) and made full boost at about 3000 but started to fll off at ~52-5400 because of its limited capacity.

But the torque/power curve closely paralleled the boost curve. Peak torque came at 3200, then the curve was nearly flat all the way to ~ 5500. So that meant you were at, or near, peak torque under almost any driving condition. It had more top gear acceleration than any car I have ever owned ( and I have owned a lot of fast cars).

MR2 owners that are serious racers usually replace the CT26 with a higher capacity turbo that moves the torque curve over to the right. That means significant gains (both torque and HP) at the high end of the curve, but a significant loss at low end. If you are a serious racer, the resulting hp increase is more important than the low/mid decrease. But when almost all of your daily driving is below, say, 4000 RPM, the small turbo is much more fun and streetable.

If I'm cruising down the highway at 60, and want to pass a line of cars, I want power NOW, not after it manages to add another thousand RPM.

After owning a car for so long that made peak torque at 3200, its been a little difficult to get used to one that makes peak torque at 4600

(Thats why seldom shift above 4th around town, and I really don't shift into 6th until I am well up to cruising speed (70 or better)

 

Damn....I owned a '93 MR2 but NOT the Turbo, The NA version with 135 HP...Sounds like I really missed out on a better driving experience..since I was eventually wishing for more HP.

But it was still one of the nicest sportscars I've ever owned!

 

Yup, all MR2s are great sports cars. I also owned an '87 before I bought the '91T.

But comparing the gen II N/A to the turbo is like comparing a 914-4 Porsche to a 914-6 Porsche. One is a Volkswagen, and the other is Porsche.

I owned both of those, too.

 

Here's how I think of the two:

Torque helps you at the start of a race and horsepower helps you at the end of the race. In drag racing, torque will get you out in front at the start while horsepower will help you motor by at the finish. In road racing torque gets you out of the corner harder while horsepower gets you by near the end of the straight.

Having raced a 240Z in ITS against the second gen RX7 I could kill them at the start by bringing the field to the green flag at about 3,250 rpm in 3rd. Their rotary engines would either be lugged down at the same rpm in 3rd or maxed out in second while my 2.4L straight 6 was in the fat part of the torque curve. When the RX7 had the pole they would come to the green flag fast at 5,500 rpm in 3rd and I couldn't keep up when the flag fell, being already right at the torque peak.

 

You mean "relational" and "proportional".

Proportional means "having the same or constant ratio". In other words, identical. If I cut a pie perfectly in half and give you one half and keep the other, we would have proportionate pieces of pie.

Relational means they are not necessarily identical, yet related. Since hp is a function of torque, they are obviously related.

You are obviously referring to just one point on the axis. In that case the RPM input to the HP function is a constant, and what you said is true, but a 5% change in torque will net different results at different RPM.

I don't know many people who look at a powerband in terms of a single RPM.

So my lawnmower engine won't compete with the vq?

 

6200 to 7000 please!