Question on RPM's/power band.

[jasonaries]

Hey, was wondering what your m.o. is for operating in the power band? You know, your favorite range of RPM's for power or engine braking. How did you arrive at this? Do you tend to describe it as a percentage of redline, or as a number specific to, say, the 100's?

If you happen to drive an AE86 SR-5 model, I'd be most curious in your answer.... I know many of us have multiple cars, so please specify which car goes with your answer. Thanks.

[SidewaysGts]

I have a gts, i find above 4400 rpms on up to around 7000 is my desired range. i dont like going above 7000 for just safety issues, as for 4400... well u just got an 86 i believe? im sure u notice the difference when the tvis opens up as well.

[malcolm]

I've got an AW11 (same engine as you), and it feels like a lawnmower engine in the back until 4200 rpm, when it starts to pick up. Like GTS said, 4400 is when it comes on strong. I find mine starts to drop off a bit past 6500 rpm. (I have a re-arranged intake, and a stock exhaust... I am sure it would be a little better if I put on a better exhaust system)

In the 'vette, it seems to come on strong at about 4000 rpm, and pulls hard to about 6300 rpm with the cam we have in it.

by the way, what does "m.o." mean?

[jasonaries]

Cool.

M.O. = mode of operation. I was fishing for something like: "I feel the engine kick in at 4500 and power start to diminish at 6500, so I try to keep it in that range while lapping/racing." I was also searching for your preferred RPM target when downshifting. Another angle to answer could have been giving how long you hang out near redline. For example, if my GTS 8-6 ebbs at 6500, I may be inclined to not push it to 7250. My head must've been foggy when I first posted. Part of it is that my inexperience is causing me to not know how to ask the question in a cool way. But I am able to wring the good tidbits out of your answers.

Hey, what's TVIS? (Oh, man, I hope it's not something obvious.)

[SidewaysGts]

Tvis: Toyota variable intake system.

the 4age has a double valve restriction on intake, a "butterfly valve"

When below 4400 rpms, one valve is closed. An engine will suck in the same amount of air right? since its moving al lthis air through a smaller hole, it actually sucks it in faster, forcing it to mix better and what not with the fuel comming in..effectively bringing up the torque and horsepower in the low range.

Any way u look at it; this is restriction and only helps to a certain point, or 4400 rpms. At 4400 rpms the tvis opens up and the restriction is removed.. ahh happy engine

Malcom is right about the powerband; the 4age stock at least only makes power up to around 6600 rpms. The engine is easily able to rev all the way to its rev limiter at 7800 rpms.

For tje record: i shift right at 7000 rpms usually. You may not make more power but keep in mind, the higher up you go- the less youll fall in your power band.

Its a double edge thing, i dont make more power, but i dont lose time picking it back up after the shift.

As for downshifting: just downshift as your about to fall out of your powerband... 4400 rpms again so 4500-5000 and you should be fine.

[CrazyHawaiian]

I dont really understand the question. Its not up to the driver to determine what the powerband will be. It all has to do with how the engine is built. And the way you find out what works for your car is to go give it a try. The goal is to keep it in the powerband at all times so that you can push more power when you need it. Cant really answer this over the internet for your specific car, you're better off with real world experience. Best thing for you to do is determine the powerband by feel, remember the RPM's, and then also remember your speeds at different RPM's in different gears. That last part will help you determine at what speeds you can downshift into what gears.

[SidewaysGts]

When u reach the upper speed of the next gear down, downshift

[jasonaries]

SidewaysGTS & Malcolm: Good team work here.

I agree with all the comments on the 4200, 4400, and 4500 points on the tack. My intuition and limited experience backs that up and I appreciated the input.

I will most likely be the type to shift sooner and not hit the rev limiter BUT I'd like to know why pegging it to 7800 is not a problem? Is it that there's x amount of stress on the engine past 6500 and it doesn't change beyond that level, no matter how high the needle goes?

Crazy Hawiian: Re - powerband by feel, remembering RPM's and knowing the matching speeds.... Thanks for reading and chipping in. The comments that you made are helpful, too. I have taken great care to do as you suggested, but only so far as in normal everyday driving and endurance driving. This question had a slightly different flavor in that I was trying to pick their brains for how to adapt my skills to racing and from the SR-5 to the GTS. I'm a beginner. Malcolm and SidewaysGTS have given me some clues and backed up some observations of mine. It re-affirms that I need to branch out and explore the higher RPM's at my own pace. I don't drift yet, nor could I really race yet - but I'm getting there. I'm still laying the foundation. I really love this, though. It's as fun as my martial art and flying sailplanes and skiing. oops....blah blah blah... I just get goin' sometimes...

later,
jason

[SidewaysGts]

it can get up there easily enough i just dont suggest sitting there for long. Rev limiters are there for a reason, to keep your engine from going -boom-

Sit there too long and your putting a LOT of stress on the internals. In specific Connection rods (connect the piston head to the crank shaft) and even more at risk are the conrod bolts themself that hold the conrod (for short) to the crank shaft. If any of these go, your likely to break that conrod easily and send it right out the side of your engine. An other thing to worry about are your bearings that let the conrod spin around the crank shaft. theres a oil "film" between the metal bearing and the crank shaft it self, go too fast and your likely to break the oil film, get metal to metal contact, and break the bearing.. thus which would probably break a conrod (dam nthose bastards lol) or you can "throw" a bearing, and have it just go boom from high engine revolution speed and stress.

Then theres just plain heat.

The 4age is a pretty solid and pretty damn reliable engine becuase it has an iron block, so its pretty strong and takes a *Censored**Censored**Censored**Censored* load of abuse but even the 4age has its limit.

Lastly.. theres not much point to go beyond 6600 rpms, where the power drops off at. why push an engine close to its limit for no reason?

[Cade]

I start to budge at 2,700 or so. But I like it around 5,500 - 7K. Going through the twisties around that rpm, letting off and stepping back on it and watch it whistle right back to where it was. MmMm thats one of the highlights of when I go driving.