Break-in 06 Sienna CE

I didn't time the process, 2 minutes is my guess. Keep in mind that redline is the maximum SAFE engine speed. The analogy is that driving 55 MPH in an area with a 55 MPH speed limit is safe, absent other factors that require a lower speed. Modern computer-controlled engines have RPM limiters to protect the engine.

As far as having second thoughts, all Toyotas go through that test, it is the 2nd or 3rd to the last station on the assembly line, and given the millions of vehicles they sell each year and how long most of those engines last, that test does not seem to be doing much harm. That test validates the engine, transmission, wheel balance, and emissions.

The folks at Toyota who design QC procedures are pretty knowledgeable about what they are doing and are not likely to implement a test that shortens the life of the product.

The reason that I suspect some engines have blown during that 2 minutes is that it is difficult to believe that anyone could produce 10s of millions of engines without ever having a failure. It is possible, but not likely, and if an engine is going to fail, it is better to have it fail at the factory than in a consumer's hands.

: As a matter of fact, I owned an '81 Accord sedan for over a decade.

Not in any way that's relevant here: it was an engine with a high power band and a correspondingly high redline. It would turn close to 4,000 RPM at 70 miles per hour. That was gearing, granted. But the point is that it was geared that way for a reason.

: Even Hondas have redlines, high though they may be. And hitting : redline, even frequently, isn't the same thing as running an engine at redline for minutes at a time.

Why would anybody do that? Run an engine within 500 RPM of redline continuously, I mean? Seems to me you'd want to upshift if the engine ran that fast, and that you could do so without sacrificing power. I've never heard of a street engine with a power band right up against its redline, and with good reason: such an engine would be impractical for day-to-day driving.

Geoff

4,000 RPM at 70mph??? That is nowhere near high RPM. I used to have a 1974 chev 3/4 ton 4x4 that was 4,000RPM at 72mph. That was a big block chevy 454ci. Redline was somewhere around 5000 and the valves started floating not too much faster than that. (Oh, and no upshift at 72mph as the 3speed automatic transmission had nowhere else to go. Can't drive too many hours at 75mph even with dual tanks.)

I'm currently driving a 1996 Ford Ranger with a 4.0L pushrod v6. Once into overdrive (4spd automatic) it does about 3000rpm at 70mph. And I've spent many hours never dropping below 80mph. Redline (according to the rev limiter) is 5800-6000rpm.

My Sienna cruises at about 2500rpm and is perfectly willing to rev over

2x that fast. I see no need to keep the rpm any higher, nor any particular reason other than fuel economy to avoid it.

Those first two are OLD TECHNOLOGY engines. I'd expect a modern tech engine with light pistons, overhead cams to eliminate the pushrods, etc to tolerate 4000rpm without any problem. And have you looked at high rpm engines lately? 10,000 RPM is a starting point.

Look at two-cycle and modern four-cycle (street performance) motorcycles and small performance/sport cars with the performance 4-cylinders.

sdb

: Not in any way that's relevant here: it was an engine with a high : power band and a correspondingly high redline. It would turn close : to 4,000 RPM at 70 miles per hour. That was gearing, granted. But : the point is that it was geared that way for a reason.

Since your truck had to go 72 MPH versus my Honda's 70 in order to turn

4000 RPM, I'm not sure I understand what point you're trying to make by mentioning it. I didn't say my Honda was a record-setter as far as RPM/MPH was concerned; I merely said the engine had a high power band and was geared accordingly (heh). ("It's a prelude to a more civic accord!")

I didn't claim that the characteristics of my car's engine were without parallel, so there's little point in trotting out examples of engines with similar characteristics.

Its being "perfectly willing" to rev that fast isn't the same thing as it being *necessary* to rev the engine that fast in order to extract power from it. And the reason it isn't necessary is that the engine has a relatively low power band. Which was what I was talking about in my previous post.

A starting point? What unmodified, production street automobile engines have redlines of 10,000 RRM or higher? Even the Honda S2000 redlines at "only" 8,000 RPM (down from 8900 originally).

: I've never heard of a street engine with a power band right up against : its redline, and with good reason: such an engine would be impractical : for day-to-day driving.

I'm talking about cars, not motorcycles. Motorcycle engines do generally rev a lot higher than automobile engines. As for small high-performance cars with 4-cyliner engines, yes, a lot of them are very peaky. But are they typically so peaky that they have to be revved right up to redline routinely, in order to get any power out of them? Not "can they be," but "do they *need* to be?"

Geoff