Bummed over a blown engine I understand, but getting to 7100 RPM on a street car that redlines at 6700 rpms I'm having a little trouble with. Without some substantial mods these engines aren't designed for that high a rotation and though they can take it from time to time, I haven't seen one that does much but spin over 5500 rpms. Aim for the torque peak and shift. Leave the higher rpms for the motorcycles.

 

lol at this post.

 

Evidently you're not familiar with transmissions and gearing advantages. By and large I would agree with your statements for street use though.

- Matt

 

I agree herbie, I know of a racer that made and intake that is actually is divided. That air coming from one end isn't a good design. It works well. she went from twin charging to just turbo. Something silly like 40psi for a while. kept lifting the head off the block. I think that car is for sale now. she went for an open wheels Mazda racer. I also have one of her old sets of wheels, header and exhaust.

 

ZOMG! What has Honda done, making us think we should actually allow 9k redlines on the street

 

what's wrong with 9k on the street?

 

I never shift before 7... ussually 7500... and when I am in it to win it 8k... i did hit 9400 once.... buuuut I try not to do that too often... as I am still using a stock head and valve train... sounded great though...


who says these engines aren't designed for that? Just because the manufacturer doesnt do that doesnt mean they cant. Their guidelines for what they are trying to archive is totally different.


actually never mind... no one rev yer mini past stock! it's daaaangerous!

 

once again sir, I say to you....UNPOSSIBLE!!

 

me = jealous, i have your car as my desktop background, hope that is okay

 

Jesus christ...9400.

I love it.

I've always been a fan of oversquared, big-bore tiny-stroke setups.

- Matt

 

of course that's ok.... it's an honor

yeah me too!

 

Any new updates, mario?

tüls, next time you hit 9400 rpm, get a sound recording for us.

 

Maybe I need to be enlightened, but any engine has a finite power band. When you exceed those limits (especially the red line) on a regular basis, you can expect it to fail prematurely regardless of what gearing you use to get the power to the road. Those who wish to run above those limits will keep parts suppliers and repair shops very happy.

 

I spoke to Danny today and all the parts are being looked at. I told him I just want a new crank with bearings. To me its not worth saving $200 for a rebuilt crank with over sized bearings. I will be getting new gaskets, oil pump and some small other stuff but it shouldn't be too bad. It might be time to trade in my bad luck black Mini.

 

First, you said 5500 RPM. This is not even approaching the limits...you're only at ~80% output.

Second, and almost without exception, you want to stay in a lower gear as long as possible. To use arbitrary numbers as an example, say you have an engine that puts out 150lb/ft at 4000RPM (peak torque), and 100lb/ft at 6000RPM (redline), and have a transmission with 4:1 1st gear, and 2.5:1 second gear (excluding final drive).

In 1st gear:
- @ 4000RPM : 600lb/ft
- @ 6000RPM : 400lb/ft
In 2nd gear:
- @ 4000RPM : 375lb/ft
- @ 6000RPM : 250lb/ft

That's all at the wheels. As you can see, it makes sense to use your first gear for as long as possible, even though you're past your "power curve." This is true for nearly every car on the road...no car I am familiar with has such a steep dropoff that it would make acceleration sense to switch to the next gear...most cars plateau or only slightly dip. F1 cars have incredibly low torque figures, but they rev so high and have a transmission that can take advantage of it (if I recall correctly, they only have around 200 lb/ft at the crank).

Also, this is a very simple way of looking at it. I'll have to see if I can dig up this great website that does a much better job of explaining it and putting it all into context...gear ratios, horsepower, torque, etc.

- Matt

- Edit -

Think this was the website: http://www.allpar.com/eek/hp-vs-torque.html
To use engine torque to understand how your car performs, you MUST include the effects of the transmission.

 

How about over 200ft/lb at 6800 .

Shift at 5500 .

Longboard

 

wear goes about with the square of the speed. But don't fool yourself into thinking that parts don't wear if you drive gently. they do, just less quickly.

Second, the stuff about when to shift is good for full throttle acceleration, and what you're looking for is called a thrust curve. This one is for the 02 MC 5 speed.

It just depends on the torque curve for the engine and the gear ratios (and something called the effective mass) to plot the crossover points. For the 5 speed MC, you DO run to red-line in first, for the 6 speed MCS, you don't.

Matt

 

that is a really interesting graph, esp for an r50 owner like me, where did you get that info from?

 

Thats what makes him the Dr.

Longboard

 

Tell me Dr, what are the shift points for the S? This is a case of me not doing all of MY research I guess...looking the at the plots for power and torque for my engine with the 15% (and with an 02-04 gearbox), I was under the assumption that shifting late was best.

Looking to know more from a true engineer. =) I eat my words when I'm wrong...usually it tastes like poo.

- Matt

 

got the gear ratios, and estimated the effective mass (That's how the rotating parts effect the total work needed to get them spinning as a function of gear) and put it into excel.

For 07 MCS, no overboost
1-2 shift 6200 RPM
2-3 shift 6600 RPM
3-4 shift 6400 RPM
4-5 shift 6100 RPM
5-6 shift 6000 RPM

For 02 MCS
1-2 shift 6300 RPM
2-3 shift 6400 RPM
3-4 shift 6400 RPM
4-5 shift 6600 RPM
5-6 shift 6900 RPM

The 4-5 and 5-6 shifts are pretty academic (both over 100 MPH), but that's what the math gives.

Matt

ps, working it out for different torque curves is pretty easy, but I'll leave that as an exersize for the student! Can't make it all too easy!

Matt

 

I thought this was America: it should be on a silver platter for me already, spoon in my mouth.

Thanks for the listing. Not too far off from redline though.

- Matt

 

I hope you guys really like your mechanics. I sounds to me like you'll get to spend plenty of time with them. I just looked at the sales brochure for my car and the specs page states the torque peaks on the MC @ 4500rpm and the MCS @ 4000 rpm (this would explain the need for the 6 spd gearbox in the MCS). Horse power peaks @ 6000 rpms for both. The dyno charts I've seen for modded cars go slightly higher, but I have always found that the torque peak was far more useful than the horsepower peak for forward momentum on any car. By the sound of it I still be enjoying my car long after yours becomes a memory.

 

I am not sure what you mean.......

 

It makes sense that upshifting after a lower gears intersection point on the thrust plot would equal a slower rate of acceleration, as would upshifting early. Full throttle acceleration from a stand still is an art. I'm no artist. That's why I'm leaning heavily towards a LSD for autocross season!

What about our MINI's shape/air drag Matt? Would that move upshifting above 2nd gear different from the curve, excluding 5-6 shift? Ahh I guess it doesn't matter as all of our MCSs are different(motor, SC pulley size, intake, exhaust, trans, tires, condition of components, etc) and will have different curves anyhow......

Jeremy