Has anyone taken their engine up to the redline (6800 RPM)? 5000 RPM is my max as it sounds like it's about to fall apart at that point. I'm sure it wouldn't, but it's not any enjoyable sound.

 

I've gotten up to 6000, maybe 6200-6300 on some on ramp somewhere. It's loud. It doesn't sound terrible or destructive. But I used to drive a diesel. Revving that engine to 6000 absolutely would have killed it. So I'm not used to winding it up (or having to).

 

Yes, I redline the engine regularly. Especially in 2nd gear it's pure fun to accelerate wide open throttle from junction up to highway speed and redline. Best range is from 4000 to redline. The rpm limiter is there to prevent damage and manufacturers set the limit very conservatively. You can drive the engine against the limiter as often as you like and there is no risk of braking anything.

 

You might have a loose heat shield, bad accessory bearing or something. The CVT will happily take the engine to its peak power point (6600 RPM) if you floor it. Honda got its start as a motorcycle company. Motorcycles don't have room for and can't carry the weight of large-displacement engines. To get power out of a small engine, you need to spin it faster. That's why sports bikes often have redlines in the 10k-14k range. Nearly all Honda engines hold onto some of that heritage, handling trips to redline in stride. The few RPM-challenged Honda engines are considered specialist designs or engineering defects. Rev out the engine at least once an oil change to help blow out carbon and other deposits. It's tongue-in-cheek name is the "Italian tune-up".

If you can even get it to rev that high. Diesels differ from gasoline engines in that there's no time for the fuel and air to mix before it ignites. In a diesel, the fuel and flame front are constantly chasing the fresh air supply as it retreats down the cylinder with the piston. Diesels don't rev high simply because there isn't enough time to burn the fuel at high RPM. The air supply and compression heat (which ignites the fuel) fall away from the fuel spray, resulting in a half-burnt conflagration blowing out the exhaust port and a huge loss of power.

 

Diesel governors always have an rpm limiter to prevent mechanical damage in no-load revving. It reduces the fuel injection when reaching the set rpm. In mechanical governors there is a adjustment screw for the max rpm, and many generations of expeditionary unknowlegable tuners have broke diesels by setting it too high. In diesel emission opacity test the engine is revved up to the limiter.

The burn rate limit is not a true limiting factor in diesels. It's the mechanical strength of the internals. As somebody said, the burn rate limit is misinformation that has been repeated so many times it has became a fact when in fact it isn't.

 

Are you sure you're not hearing the VTEC cam-shift at high RPM?

As other said, if you have a really weird noise at a certain RPM, it is almost certainly something loose and vibrating/resonating on your car (noise is just vibration after all). With your location in Maine, it is not out of the question that heat shields or other exhaust components are getting rusty and loose.

I once had a tiny amount of gravel trapped between a heat shield and the muffler on a Toyota Yaris. It was perfectly normal at idle but when you passed through the 2000-2500 RPM range, as you did with each gear shift or when cruising at 55 mph (~2250 RPM), it sounded like the engine was about to grenade.

 

The fuel injector can fire a jet of fuel at the piston and expect a piston feature to break it up into a burnable mist. Fuel pressure can be increased (within the physical limits of the plumbing) to increase fuel jet velocity. Short-stroke over-square engine design can reduce the chasing effect at the expense of requiring much stronger, heavier pistons. Fuel can be grossly over-injected to compensate for the poor mixing, resulting in the "rolling coal" phenomenon.

Audi has been known for running turbo diesel race cars, including at Le Mans. The R10 ('06-'10) made peak power from 3-5k RPM. The R18 ('11-'16, including hybrid versions) similarly made peak power at ~4.8k RPM.

If it were misinformation, I think a well-funded race team would be taking advantage of the solution.

 

That well funded race team could easily make an engine, which would produce peak power at much higher rpm. Even tuners have made mechanically stock Mercedes turbodiesels to reach 6500-7000 rpm. However, that high rpm reduces reliability because the high compression ratio needed to self-ignition causes huge stress to reciprocating parts of the engine.There are higher pressure loadings and thermal gradients resulting in heavier components and greater inertial loadings. And current injection technology is not yet capable to provide fine and controlles spray of fuel in such short time, which is needed for efficient burning in high rpms.

 

No need to j be ounce it off the rev limiter….but 6,500rpm a few times a week, when the engine is good and warm, is important .

 

All I have to add is that Honda NA engines were known for revving high... that said, the L15 engines have TINY TINY rods... and high rpm stress's rods way more than "hp" does. For example, a 400hp engine that makes its power at 10,000rpm will likely have more stress on the rods than a 600hp engine that makes it's peak power at 7500rpm, even though that engine is making more power, due to the lower rpm the stress is likely less on it's rods.

All this said, the first 2 generations of Fit's and the L15's are pretty well known for taking whatever abuse you want to throw at them, tracking them for lap after lap, to crazy guys rally racing them... They pretty much never over heat short of a failed water pump or empty cooling system, and can stay at WOT for a long time lap after lap with no issues. So, going wide open throttle on an on ramp and holding the gear until redline, while maybe a bit silly depending on the situation, doubtful you're going to hurt anything if that's all you're doing. Keep in mind, syncro's tend to not love high rpm shifting, so if you care about your transmission shifting smoothly for 100's of thousands of miles, might not do that every day. Driving a bit spiritedly from time to time though on a maintained example, you're not going to hurt anything at all, have fun. (some examples have been pushed with upgraded valvetains to 8,000rpm. No one is saying to do this, just saying I wouldn't be worried about the stock redline if the rods didn't snap at 8k making more power)

(Good info here on the A1 and A7 L15's if you want to read)
https://honeddevelopments.com/differ...5a1-and-l15a7/

 

I've been under the impression it's man-handling the shifter (excessive force applied to the synchro) that causes premature wear. The amount of RPM drop while up-shifting does increase with engine speed, but the wear impact should be trivial compared to forcing the transmission into gear.

Nice link.
The discussion about the flavors of VTEC was intentionally muddied by Honda.
The 12-valve / 16-valve variety was initially called VTEC-E, debuting on the '92-95 Civic VX hatchback. The VX was a successor to the CRX HF which was built as a fuel-miser, using an engine built for low-RPM operation, long gears, chassis lightening and aerodynamic tweaks (such as deleting the passenger side mirror) to hit 52 MPG on the highway. As a successor, the VX did quite well. With some minor lightening and not-quite-as-long gearing, it got similar fuel economy to the HF while providing an additional 20-30 HP and 13 lb⋅ft of torque (comparing the D15B6 and D15Z1 if you want to look them up). However the HF engine was pretty anemic. Anemic +20 HP was still 10 HP less than the standard engine (D15B7) of that generation. That led to VTEC-E being smeared by traditional gear heads as a marketing gimmick or some kind of emissions-reduction device.
What does VTEC-E actually do? As the article states, it switches between 12- and 16-valve modes. 12-valve mode effectively only opens one intake valve. That causes a swirling turbulence in the air/fuel mix as it's drawn into the cylinder. That alone doesn't affect the air/fuel ratio - the ECU controls air/fuel ratio directly by changing how long the fuel injector is open during each intake cycle. However, the turbulence does improve air/fuel mixing and combustion stability in the cylinder. That added stability lets the ECU run the engine leaner (use less fuel) before the engine starts to stumble and lose power. So VTEC-E lets the engine cruise on a lean air/fuel mixture, then switch over to 16-valve mode to get normal-engine peak power.
The mixed reception made Honda re-imagine VTEC-E a bit while they shifted their fuel-miser work over to developing the 1st generation Insight. The following generation of Civic ('96-00) got the HX coupe with the VTEC-E D16Y5. The HX got the standard-gearing (compared to other trims) 5-speed manual, or optional CVT transmission (a first for Honda cars in the US). The "normal" gearing, along with the D16Y5's +9 HP, +1 lb⋅ft and superior fuel economy over the generation's vanilla engine should have made it a superior daily-driver choice, but people had it in their minds that "the E is for economy".
The '01-05 Civics saw a heavy re-design (ending the "golden age" Civics for most people that cared), which included the final generation of the D-series engines. The VTEC-E badge was gone, but the tech was not. Quite the opposite, the cam-profile-switching "performance" version of VTEC (previously just called "VTEC") disappeared from all but a handful of engines. All the US Civics with "VTEC" engines (including the K20A3 in the Civic Si) were in fact VTEC-E.

TLDR; VTEC-E doesn't change air/fuel ratio. I feel old.

 

You guys need to get a hobby.

How about racing Slotcars?

You can redline those motors all day long.
🤣🤣🤣🤣🤣

 

I don't know as much as some of the posters in this thread. However, I've owned three Honda automobiles — a GD, a GE and an S2000. I like to buy a new car and then drive the sh*t out of it, and that's what I have done with my Hondas. I've revved these engines all day long with no trouble. And it was — and is — a blast. That said, I am also the guy who changes his oil and filter every 3,000 mi., changes his MT fluid every 9,000 mi. and does early valve adjustments. I can't comment on the Earth Dreams engines except to say that I'm pretty sure they are not my dreams. My dreams are port injection and VTEC.

I don't get along well with people who are "afraid" to go into VTEC because they think it will hurt the engine or people who brag about getting 47 miles per gallon. Life is short. VTEC is God's way of showing that he loves us.

 

The direct injection 1.5 of GK5 surely has its drawbacks, but I can assure VTEC brings it to life as well, and the joy starts after 4000 rpm.

 

I give you the D15Z7, aka the three-stage VTEC D15B, '96-00 Civic vintage. Combining 12-valve/16-valve switching VTEC-E with lean burn, and cam profile switching performance VTEC, it puts out 128 HP @ 7k RPM, and can hit 50-something MPG with that generation's standard gear ratios. Also one of the first engines to be paired with a CVT, it's perfectly happy being held wide-open at 7k for max acceleration.

 

Is it really one or the other? Surely when you have a long highway trip you don't leave your car in second gear so bounce off the rev-limiter the entire way, right?

What's wrong with feeling good about getting good fuel efficiency? You can't legally drive pretty much any car at it's maximum speed or handing capabilities on public roads, but you challenge yourself by trying to be as efficient as possible. It is a driving skill, just like any other.

 

It is not a question of one or the other. I can be friends with anyone who is a car guy. My experience with hyper-milers is that their love of cars begins and ends with mpg. What has that got to do with being a car guy? Nothing. It has to do with being an accountant. I don't spend my life counting pennies. I spend it counting smiles.

^^That said, there is room for everyone. Everyone should do what you want. My default setting is "Freedom."

 

Right on! Each to their own. I have a sports car and my DD Fit. Yet I still check MPG for both.

 

Regardless of what or how you drive, keeping a record of your fuel economy can serve an important function (outside of being a numbers nerd, which I am).

Once you have driven your car for a while, you build a sense of what sort of fuel economy it should return -- on a long highway trip, in the winter, on your regular commute, or whatever.

If you see a big discrepancy from your expectations based on the driving you did for that tank of fuel, that is a potential indicator of some sort of problem.

It takes only a few seconds to calculate your fuel efficiency at the pump. If you want to go full-on accountant mode, it takes maybe a minute (total) to record your mileage on the receipt and then enter the mileage and gallons used in a spreadsheet once you get home. Not a lot of work for an important piece of data about the health of your car, and certainly not *Nothing* for a car guy/gal who cares about keeping their car in good running condition.

 

Duly noted. But that's not what I said. Hyper-milers are not using mpg as a diagnostic. They are using it as an end unto itself. I don't go to a banquet so that I can have dry toast and distilled water and talk about my diet.

But, as I said (or implied), it doesn't matter. We're just having fun. This isn't the cure for cancer. Everybody should do what they want. My statements should not be taken as a (negative) critique of anyone else.

We were talking about redlining the engine. The only thing redlining will hurt is mpg.