Author Topic: POLL: How high have you revved (Read 5379 times)

Boyracer · « **on:** November 27, 2007, 09:01:34 AM »

Hi there!

I am trying to find out how much allowance there is on stock M42 valvetrain (camshafts, springs, cam followers, valves) for higher revs. I know there is some designed in slack to allow loss of spring rate due metal fatigue and also for misshifts.

Why is this important? I am using stock valve spring on seat / max lift pressures to calculate how high it would be possible to rev with new, stiffer springs.

I can use 6800 (stock limiter) as basis but that means the same designed in allowance would be present with the new spring rate. Not a bad thing itself but when you go to high enough revs, you need very stiff springs which will cause power loss due friction and wear and strain on valve train components.

So basically it is good to run springs that are just stiff enough to allow your desired revs and not more.

Also, this poll can be usefull to see if there are other components like pistons or conrods that tend to break

In your post please state following:

Model (E30 / E36)
Engine age (miles / km)
How high have you revved your engine without damage (rpm)
How high have you revved your engine with damage optional (rpm and what went broke)

Boyracer · « **Reply #1 on:** November 27, 2007, 09:02:45 AM »

My entry

Model (E36)
Engine age (200 000 km)
How high have you revved your engine without damage (6800)

dude8383 · « **Reply #2 on:** November 27, 2007, 09:50:54 AM »

Model - E30
Mileage - 215,600
How High - 7,200 rpm

Wait for Febi Guibo to chime in...his motor can rev past 7.5k

strad · « **Reply #3 on:** November 27, 2007, 11:31:39 AM »

Febi spent a pile of money on his motor though. . . and it's not anywhere close to stock.

Mine:
E30
Mileage: 197,900
How high: stock redline (6300 rpms?).

sheepdog · « **Reply #4 on:** November 27, 2007, 12:02:51 PM »

You can get a stock M42 up to 7500.
How often, well, that is a different question.

Keep in mind, power falls off very fast after 6500, and by 7k, it is pointless to keep going.

If you want to keep your car up above 6500 or so for long, you need a lot of work done due to oiling issues with these engines, they were simply not designed for constant revs like that.

Many of us go by the old rotary addage, "a redline a day keeps the mechanic away". Look in your manual, even BMW recommends keeping the motor up in the revs.

gearheadE30 · « **Reply #5 on:** November 27, 2007, 03:53:57 PM »

e30
202,xxx
7000 when I first got my chip, but I only really use 6500 on autoX, etc because there really isn't much power above that and my car has a wicked driveline vibration above 7k.

I keep hearing all this cool stuff about Febi's engine. What's he done to it?

dude8383 · « **Reply #6 on:** November 27, 2007, 04:00:40 PM »

Quote from: gearheadE30;38448

e30
202,xxx
7000 when I first got my chip, but I only really use 6500 on autoX, etc because there really isn't much power above that and my car has a wicked driveline vibration above 7k.

I keep hearing all this cool stuff about Febi's engine. What's he done to it?

There is a whole thread on this...

asubimmer · « **Reply #7 on:** November 27, 2007, 05:17:01 PM »

e30
~300k
7200

1991 E30 M42 · « **Reply #8 on:** November 27, 2007, 05:59:01 PM »

E30
Probably 140,000 at the time
8000 on a missed shift

tjts1 · « **Reply #9 on:** November 27, 2007, 06:30:58 PM »

3000 in reverse. I try to keep it under 1300 in the forward gears.

dude8383 · « **Reply #10 on:** November 27, 2007, 06:53:21 PM »

Quote from: tjts1;38454

3000 in reverse. I try to keep it under 1300 in the forward gears.

you can't be serious...

sheepdog · « **Reply #11 on:** November 27, 2007, 07:26:41 PM »

Quote from: gearheadE30;38448

I keep hearing all this cool stuff about Febi's engine. What's he done to it?

Full blown Metric Mechanic 2.1 stroker motor.
He is pushing over 200hp and redlines at 7500 or 8000.

The torque rolls on just above idle and it never stops pulling.
Basically it is the engine BMW should have put in our cars, but didn't because it would have embarrassed all other e30's including the M3.

Vladi · « **Reply #12 on:** November 28, 2007, 04:57:56 AM »

E36 08/94 engine
milage not known.

7000rpm I-II-III and then ran out of track.
Usually i change gears in 2500rpm and when i hit it i change in 6000rpm.

nicknikolovski · « **Reply #13 on:** November 28, 2007, 05:08:40 AM »

Hi, here is my stats

93 BMW E36 318is M42

200,000 km's

Highest RPM: 7200RPM

tim_s · « **Reply #14 on:** November 28, 2007, 06:42:16 AM »

has febi got a proper dyno printout for his car yet? I'll post up mine at some point, only have one on the standard inlet and my daily driver (very tame!) cams, i make 183bhp (about 145bhp at the wheels), 163ftlbs, but my peak power is at 6.5k. Need to get on the dyno with my ITBs on, but my current insurance policy prohibits me from using them, plus they're a bit too noisy for daily driving

Highest I've revved mine is 7,2k, but its pretty heavily modified.