Bad to go past redline?

[02TafWhtSi]

Ok so I'm on my way to work on Tuesday and decide to have a little fun. As I'm bringing up the RPMs in second I quickly glance down to see the tach needle swing well into the 7k range (around 7300 or so) and then bounce off the limiter. The redline starts at 6800 if I'm correct. Is it hurtful to the engine to run it past 7k every once in a while (obviously not for every shift) or can it tolerate it? It's also strange that the limiter doesn't kick in until about 500 rpm OVER redline.

[DownTheHatch]

You're fine. Try to shift right at redline next time.

[civic01vtec]

Here is my reasoning on why redline in the K20A3 is only at 6800rpm. Now the only diffence so far that i have found in the A3 and the A2(in the rsx-s) is that the A2 has alittle more compression and the lobes on the intake and exhaust cams are different. Now i belive Honda has limited the readline at 6800 and the cutoff at 7300 because if it was aloud to go to the true redline which i belive is the same as the rsx-s's that it would generate more then just 160hp at flywheel as they say. So you see inorder for the Acura line to have "more horsepower" they had to limit the limits of the engine in the Si/SiR.

[DownTheHatch]

I disagree, that would mean between 6,800 and 7,300 the engine would generate 40 more horsepower. The engine has a 6,800 redline because that is the limit of the internals, going past 6,800 causes your valves to float and can lower the life of your engine.

The Type-S has higher compression, that higher compression gives the engine an additional 40hp.

[civic01vtec]

Just a small increase in compression of around 1 will not give you an extra 40hp they say. I feel that the intake and exhuast cams are different and that gives the additional power.

[02TafWhtSi]

but then why is it possible to rev it 500 rpms MORE THAN the posted redline (6800) to about 7300? Why then isn't the redline 7300?

[Mechanic]

Hell, yes, it's bad to go past the red line. If you'd like a list of the things you can antcipate if you continue exceeding the red line, pls advise.

[HondaCivicSi]

what the point of a rev limiter if when you go past redline it hurts the engine. If the engine was in danger after redline, then the rev limiter would be at 6800. I shift just before the rev limiter, which could be considered the real redline.

[Jesse02SI]

The diff. between HP in the RSX and Si is I believe
1. The compression on ours is 9.8 to 1 on Rsx its 11 to 1 i believe.. thats a nice diff in compression. they also have a heftier crank and better pistons.. but our cars are still nicer......

[fishboy]

so it is bad to hit the rev limiter alot? i don't do it alot, but i like to do it once in a while to show off. up side: i do have my shifts down where i can shift right before the limiter.

[Mr.02BlackSIguY]

i dont think it would hurt... because wouldnt the engine know that u are redline and the fuel will cut off?

[Mechanic]

Ok, work w/me here.

I have a sense that many of you haven't ever done any mechanical work on an engine. Because most cars require very little maintenance these days, that's understandable. However, from some of the posts above, it's clear to me that some of you think that Honda's ignition cut off is a substitute for the red line on the tach. It isn't. You are courting disaster if you routinely exceed the red line. And when your engine grenades, you can be certain it will never be repaired under the warranty.

First, there's nothing "magic" about the red line. As one of you said, it's the number that the manufacturer chose as the max RPM shift point. But those who chose the number didn't pull it out of a hat; they had a lot of reasons for choosing that RPM red line.

As some of you have learned, by keeping your foot to the floor, you can easily exceed the red line. The problem with doing so is that the people who designed the engine took into consideration just how much stress the crankshaft, valves, valve springs, main and rod bearings, etc., could take before something broke. That's just straight math and engineering. (Just consider for a moment that, at 6000 rpm, the crankshaft in going in a complete circle 100 times a second; pistons are going to from the bottom of their stroke to the top, stopping, and turning around 50 times a second.) When a piston get to the top and bottom of each stroke and turns around, the force on the crankshaft journal, the rod, bearings, etc., is several tons. That's TONS, not pounds, TONS.

So, if you are lucky, you may have gotten the strongest crankshaft, rods, wrist pins, etc., that Honda ever made for this series engine. And you better hope so because when the team of engineers sat down to design your engine, they knew what the engine could withstand and then added a cushion, a margin for error. And that's what you are playing with. When something lets go from the abuse you're heaping on it, it's gonna be ugly.

[02TafWhtSi]

Mechanic - that is one of the BEST answers to any of my questions I have ever asked on this board. Thank you for taking the time to fully explain the answer and help me understand that what I'm doing isn't so good:o . Everyone - listen to this guy - he knows what he's talking about:)

[Hondatech]

Yes, excellent answer Mechanic!

As for why the RSX-S and CTR make 200 horse vs. our 160? Lets see:

11-1 vs. 9.8-1 compression

VTEC on BOTH intake and exhaust cams, like older B series VTEC motors (vs. Intake only for our motors). Not to be confused with the "i" part varying the cam timing. Both engine have that on the intake cam only.

an extra 1100 RPM that can safely be extracted.

Remember, horsepower = torque x RPM / 5250. So as long as we can make torque as we rev up, we'll make more horsepower. The 200 horse i-VTEC mills have counterweighted crankshafts and beefy rods to deal with having the bejeebus spun out of them. Ours don't. With VTEC on both cams, it can also get the airflow required to make power at high RPMS. Ours only varies the intake cam (and only then, switches from opening only one intake valve to opening both intake valve)

Make no mistake, while they're the same block, the K series motors are entirely different animals.

[SmoothOperator]

I think Hondatech and Mechanic are going to be the most useful members here. Thanks guys!