understanding rev limits?

[muggle]

I'm planning on purchasing an E30 soon, and I see that one of the weakpoints of the M20 is the rocker arms after it hits rev limiter. Now im wondering, isn't hitting the rev limiter when you drive "spiritedly" a natural occurrence? And also when I watch E30's with M20s drifting, they're always hitting the rev limiter. So can someone make me understand the concept?

[Farbin Kaiber]

Not if you pay attention to your rev's, and stay within the powerband.

[jlevie]

The stock rev limiter is below the point where there is a good chance of damage to the engine. Thus on an engine in good condition that has been properly maintained there is little chance of rocker arm failure from hitting the rev limiter. I've seen enough cases of rocker arm failure where the engine was never near the rev limit to form a theory as to the probable cause. I'm of the opinion that a lack of timely valve adjustments (possibly aggravated by worn valve guides) is the prime reason for rocker arm failure. Excessive valve lash results in repetitive impact loading of the rocker arms, which leads to fractures and rocker arm failures.

[llll1l1ll]

I let my friend drive my old E30 for about 4 days and after every stop light regardless of where we were it would be a rev-limited shift up to the speed limit. A rocker arm eventually broke.

Just make sure you keep up on oil changes and valve adjustments. I did not in my old E30 and that's what happens.

Granted, if you bounce the rev limiter all the time something will break.

If I recall correctly, the stock powerband on an i motor sort of tapers off before the rev limiter -- near 5800 or so. Hitting the rev limiter is sort of gimmicky, anyway.

[2.5-12]

rev limiter is 6,800 on the M20B25 right?

is 6,500 safe? I manually upshift my slush-o-matic to try and get some more power occasionally and I let it get that high

I do keep up on oil changes though

[SpecM]

rev limiter is 6,800 on the M20B25 right?

is 6,500 safe? I manually upshift my slush-o-matic to try and get some more power occasionally and I let it get that high

I do keep up on oil changes though

I think stock rev limit is supposed top be 6300, but up to 6800 or so is pretty safe

be nice to that slush-box tho, it's not as tough as the m20 is

[2.5-12]

stock redline is 6,300

the 153 and the 173 rev past 6,500 with no limiter action - I would imagine 6,500 should be safe on such an overbuilt engine (given the weakest link breaks at repeated hits of 6,800-7,000prm

I want this slushbox dead, I refuse to be nice to it! especially since it NEVER kicks down and upshifts at 4,500 rpm no matter how hard Im flooring it, haha

5-speed is in its future.

[muggle]

If I recall correctly, the stock powerband on an i motor sort of tapers off before the rev limiter -- near 5800 or so. Hitting the rev limiter is sort of gimmicky, anyway.

So lets say if I were going to drift, it'd be best to have another rev limiter and adjust it to somewhere around 5800rpm?

[2.5-12]

program your rev limiter to 6,300 and you can stay up there all day long as long as your head bolts are strong and you keep the oil and water at the right temp

[muggle]

program your rev limiter to 6,300 and you can stay up there all day long as long as your head bolts are strong and you keep the oil and water at the right temp

sounds legit.

[SpecM]

sounds legit.

somewhat

m20s in good shape shouldn't have problems with oil or water temps, with or without high revs

[george graves]

So lets say if I were going to drift...

Sigh.