Driving the M30 (3.5L six) engine hard

[Jay 535i]

Many of you know that my car is now a 5-speed, and has been for about a month. So I'm getting used to driving the car as a manual and extracting the most from it like I never could before.

My question is about approaching the redline. As a habit, I never rev beyond 5500, even when driving pretty hard. But my car's no monster, so shifting at 5500 when really moving puts the next gear a little lower than I'd like in the rev range. Revving another 1000 RPM or so would make the next gear really fly, y'know?

Anyway, I've never allowed myself to use that last 1000 RPM because of mechanical sympathy and wanting to spare the engine excess stress. On the other hand, I figure BMW knows where to put the redline, and if they say 6500 (redline) is okay, it must be.

Anyway, am I wise to stay 1000 RPM short of the redline, or is using all the engine's RPMs harmless? What's the rev limiter feel like in a 535, and is there any harm in hitting it now and then? I've never let myself hit the limiter for fear of finding out the painful way that there isn't one.

Please educate me. I want my car to last a loooong time, but at the same time I want to extract every ounce of fun it has to offer. Thanks in advance.

[genphreak]

Do a valve adjustment and try it ;) If in good condition she can handle redlining. I'd expect you'd need to increase the limiter or thrash (ie abuse as opposed to use) it quite badly to see any trouble. But someone with a few M30 builds to their name would be far wiser than I on this... :) Nick

[Derek A.]

I see redline all the time. About to turn 200,000 miles without an issue. I run 15w50 mobil one and change it every 5,000 miles. Valves are adjusted every 20,000.

[rob101]

i think i took my m50 to 6500 in 3rd the other day
its not like i could watch the tacho, by that stage your going pretty darn fast. but i saw it creeping up in my peripheral vision, though I haven't hit the cut off yet. (nor do i want to really)

[Bill R.]

is made on your car is 4k rpm, the horsepower peak is at 5700 rpm, there is no point in revving past the 5700 if you catch the next gear close to the 4k torque peak. The torque curve on this engine is fairly flat so you're going to gain very little but revving past 5700 if any. Since your past the horsepower peak at that point the engine accelerates slower up until you shift, if you shift right at the horsepower peak and the gearing places you anywhere near the torque peak rpm of 4k then you won't gain anything by shifting later. You'll have to check what rpm each gear ends up at if you shift right at the hp peak of 5700. If you continually bring the engine up the 6500 you eventually will bounce it off the limiter, if you bounce it hard enough such as a missed shift or a downshift to the wrong gear then you will float the valves and you will bend valves and break rocker arms if this happens.





Many of you know that my car is now a 5-speed, and has been for about a month. So I'm getting used to driving the car as a manual and extracting the most from it like I never could before.

My question is about approaching the redline. As a habit, I never rev beyond 5500, even when driving pretty hard. But my car's no monster, so shifting at 5500 when really moving puts the next gear a little lower than I'd like in the rev range. Revving another 1000 RPM or so would make the next gear really fly, y'know?

Anyway, I've never allowed myself to use that last 1000 RPM because of mechanical sympathy and wanting to spare the engine excess stress. On the other hand, I figure BMW knows where to put the redline, and if they say 6500 (redline) is okay, it must be.

Anyway, am I wise to stay 1000 RPM short of the redline, or is using all the engine's RPMs harmless? What's the rev limiter feel like in a 535, and is there any harm in hitting it now and then? I've never let myself hit the limiter for fear of finding out the painful way that there isn't one.

Please educate me. I want my car to last a loooong time, but at the same time I want to extract every ounce of fun it has to offer. Thanks in advance.

[Qube]

I usually take her to 6k if I'm in a good mood and like to hear the roar through the K&N. Enjoy it :)

[Ross]

Rev it till it won't rev no more!
Seriously, are the engines in the same state of tune (cams,fuel & spark maps) for automatic and gearbox equipped cars?

[Robin-535im]

Someone, Jim Rowe of Metric Mechanic I think, had some thoughtful words on the redline issue. IIRC, and it's fuzzy, a couple seconds above 6k or so is fine, but not to leave it there for many many seconds or minutes.

Not a scientific measurement... but I (and others) push it up to the "no more gain" point like Bill said on a regular basis, and surely it reduces the total life of the engine but it makes it more fun to drive. I see it like I'm paying an extra fee for enjoying the car to the fullest, and that fee comes in the form of a slightly shorter life to the engine. Then again, I bet 99% of the M30 cars die from some bozo causing an accident, and not from engine failure - so you're probably most likely to total the car in an accident than to ruin the engine no matter how hard you drive.

Now if you miss a shift... it's toast!

- Robin

[Toomas]

If all the bearings are fine and oiling works and valves are adjusted and springs are good then i wouldnt worry about hitting the limiter too much.
But take it easy for a while untill you are 100% confident with the gearbox or you may miss a gear, i have gone to 3rd when i wanted 5th because i had just got the car and didnt know the box very well, thankfully it was at like 100km/h so no damage done.
Now each time i have to change to 5th i take the extra second and make sure i am going to 5th.
3rd and 4th are rather hard to miss.

[Paul in NZ]

you can really feel the the tourque peak,at 4000 i never rev to the redline and its seconf to third that has the biggest jump once youre in third 5500 6000 is really ok,unless youre aiming for a top speed run where a few hundred rpm makes ALL the difference...so keep it around 5500 and enjoy the best of both worlds..

[Jay 535i]

is made on your car is 4k rpm, the horsepower peak is at 5700 rpm, there is no point in revving past the 5700 if you catch the next gear close to the 4k torque peak. The torque curve on this engine is fairly flat so you're going to gain very little but revving past 5700 if any. Since your past the horsepower peak at that point the engine accelerates slower up until you shift, if you shift right at the horsepower peak and the gearing places you anywhere near the torque peak rpm of 4k then you won't gain anything by shifting later. You'll have to check what rpm each gear ends up at if you shift right at the hp peak of 5700. If you continually bring the engine up the 6500 you eventually will bounce it off the limiter, if you bounce it hard enough such as a missed shift or a downshift to the wrong gear then you will float the valves and you will bend valves and break rocker arms if this happens.

So, regardless of whether or not redlining is harmful, it is pointless. Glad to know that. Now I can shift at ~6000 and know that I'm both avoiding the redline and getting the most out of the M30.

Thanks!

I should do that valve adjustment I've been putting off, though...

[Morgenster]

Does this apply to the M50?
Cause I never let it go past 4500rpm. I'd also like to know how far mine can be pushed.
Does anyone have torque and HP curves for the different engines?

[Paul in NZ]

try revving it out to six.....

[Bellicose Right Winger]

Wear and tear issues aside, the key to acceleration is to maximize rear axle torque. Engine torque is multiplied by the transmission ratios. Torque multiplication is why acceleration is greater in the lower gears. In the case of M30 E34's, the torque multiplication is 3.83x in 1st, 2.20x in 2nd, 1.40x in 3rd, 1.0x in 4th, .81 in 5th. The rear axle also multiplies engine torque but it's effect is the same for any transmission gear so it can be ignored for this discussion.

For the best acceleration, upshift at an RPM that will deliver greater rear axle torque in the higher gear. In most cases with wide ratio transmissions, and flat torque curve engines, the torque multiplication from the lower gear ratio outweighs the effect of torque falling off at high RPM, and you should run to the redline.

As an example, shifting at 6500 RPM into 2nd gear drops engine speed to 3730 RPM. Is 3.83 x torque at 6500 RPM greater then 2.2 x torque at 3730 RPM?

Shifting at 6500 into 3rd gear drops engine speed to 4140 RPM. Is 2.2 x torque at 6500 RPM greater the 1.4 x torque at 4140 RPM?

The optimum shift point depends on the shape of torque curve and transmission ratios.

Paul Shovestul

[rob101]

Does this apply to the M50?
Cause I never let it go past 4500rpm. I'd also like to know how far mine can be pushed.
Does anyone have torque and HP curves for the different engines?
lol
m50's valvetrain and rods and build very solidly
so you can rev the crap out of it.
i rev her to 6k when she's warmed up
as for revving it before the oil is warm DON'T thats a sure way to wear the engine out.

[Jay 535i]

As an example, shifting at 6500 RPM into 2nd gear drops engine speed to 3730 RPM.

My gears seem to be stacked much closer than that. Shifting at redline drops the revs by about 2000. Your figures put it closer to 2800.

I don't know what my gear ratios are, but I'm using a 3.91 rear diff which effectively gives me a relatively close-ratio box.

[pyro]

i missshifted the m50 non vanos and the tack went to the 8 in the mpg guage... nothing broke! Im 100% shore a vanos m50 would have died because the m50 non vanos has the double valve springs.

[rob101]

i missshifted the m50 non vanos and the tack went to the 8 in the mpg guage... nothing broke! Im 100% shore a vanos m50 would have died because the m50 non vanos has the double valve springs.
damn

[Bellicose Right Winger]

Interesting. My '90 535 is an auto, but the owners manual lists the ratios for the MT also. What did your trans come from? I can estimate your ratios if you tell me the vehicle speed and engine rpm at one point in each gear. Accuracy will be better if you choose a high rpm.

Paul Shovestul



My gears seem to be stacked much closer than that. Shifting at redline drops the revs by about 2000. Your figures put it closer to 2800.

I don't know what my gear ratios are, but I'm using a 3.91 rear diff which effectively gives me a relatively close-ratio box.

[Jay 535i]

Interesting. My '90 535 is an auto, but the owners manual lists the ratios for the MT also. What did your trans come from? I can estimate your ratios if you tell me the vehicle speed and engine rpm at one point in each gear. Accuracy will be better if you choose a high rpm.

Paul Shovestul

The transmission is from a manual 535, so the figures in your manual are probably accurate. I don't really care though what the numbers are. All that matters is that I like it -- and I do :)

[alishahna]

No I have a 92 535i 5spd and I run it between 4500 to 6800 RPM just because I have the Dinan Chip but I noticed that my power band is from 4500 to 5800 if I push it over 6200 I see my self loosing power.

[Wyn]

Does this apply to the M50?
Cause I never let it go past 4500rpm.
You're not living at all.

I get it up to about 6250 all the time and have never had any major engine problems, 222K miles and still running strong. Serioiusly, how could you not rev it any higher than that? The m50's redline is that high for a reason.


And besides, the sound it makes when you "clean the carbon out of the cylnders:D " is more than worth it.

[Barneyboy]

Hi Paul,
Ian here in Aussie, I also have a 1990 535is manual, only difference is I have a Remus muffler on it . Have you any idea of standard performance figures for the 535is . My son has a manual 535i Exec, but my gear ratios seem a bit lower than his .
Any help would be appreciated .
Cheers,
Ian.

[Paul in NZ]

i beleive the "is" has a diff ratio of 3.64 and the "normal" 535 is 3.46
I have a smaller rearmuffler (I think) and my car dynoed at 139 kw,on a dyno thatthe hubs are bolted to the dyno itself no wheel slip,which was a bit more than a mates 535 is with a std exhaust

[ILoveMPower]

I love taking the M30 up past 4k rpms, thats when she really sings to me.

I've bounced the limiter twice from rapping 2nd gear out a bit too much, but she didn't seem to mind. Of course, I'm sure it would be much different if you missed a gear.

But yeah, when going for ultimate acceleration, I've found that taking 2nd gear up to 6k RPM's sets you up very nicely in 3rd, but for all the other gears 5700 is about all you want to do.

-Jeremy

[nixter]

I was always a little nervous as well but as long as you're engine doesn't have any major issues it should be fine. I did it regularly now on the M5 and damn does that sound bring a smile to my face. You'll also find that the more you do it the better your throttle response will be in general. For a 13/14 year old car I'm still amazed at how fast this thing goes.

n

[Morgenster]

You're not living at all.

I get it up to about 6250 all the time and have never had any major engine problems, 222K miles and still running strong. Serioiusly, how could you not rev it any higher than that? The m50's redline is that high for a reason.


And besides, the sound it makes when you "clean the carbon out of the cylnders:D " is more than worth it.

Well, I'm giving it more lately and nothing's blown up. Too bad I can only push it this hard on petrol and not LPG. The roar makes heads turn :) .
What's sad is that the engine sounds happiest (is this even possible?) at a little over 4k RPM highway driving and that's over the legal limit in fifth gear (120 km/h).

As for not living: I've had my driver's license for less than a year now and if I'd have gone and floored it every time there'd not be much living. Not with the traffic we have :( .

[Old F4 Pilot]

You're not living at all.

I get it up to about 6250 all the time and have never had any major engine problems, 222K miles and still running strong. Serioiusly, how could you not rev it any higher than that? The m50's redline is that high for a reason.


And besides, the sound it makes when you "clean the carbon out of the cylnders:D " is more than worth it.

Gentlemen,

I've got an early production E34, 525i ( 12/88 build date) with a pure stock M20 engine and automatic, both original & with 317,000 miles on them with no rebuilds and I bump the limiter quite a few times. To get the most out of the M20, I have to manually shift the automatic and regularly hit 6200~6500 rpm and have felt the limiter kick in quite a few times. It also limits top speed (even downhill) to about 128mph, no ifs, ands, or buts! All I've done is rebuild the suspension and added Bilstein HD struts front & rear, (they're brutal, but just right after 100,000 miles of break-in). To stop that monster, I use mintex beake pads on cross-drilled rotors F&R.
I also acquired a 1990 535i with a 5-speed that I'm in the process of bringing up to factory specs. I wanted a little more fun in my old age.

[Wyn]

F4 Pilot, Right on with driving the car with fun in mind :D . I have 222k miles on my car and it revvs happily up to 6300 RPM whenever I want it to. It absolutely LOVES onramps and is happy to race up the tach with no fuss.


F4, What branch were you in? And were you ever carrier-based?

[The Bigfella]

Go on - rev it!

The main factor that will cause problems is cold (or dirty) oil - and believe me, the oil heats up a lot slower than the water. That is why the M5's have the oil temperature guage in addition to the water temp guage. With mine, you need to drive at least double, closer to three times the distance for the oil to come up to temp. The manual says "do not exceed 4,000 rpm until the oil is above 50C"

I typically keep below 3,500 until it is over 50C and don't redline until its at least 75C. Saw 7,500 in second yesterday while overtaking - seems the unknown chip has a higher than stock limit. I've got a standard and EAT chip coming to play with - but ordered the standard 7,200 limit on the EAT.

Ian

[hakwuzhere]

i missshifted the m50 non vanos and the tack went to the 8 in the mpg guage... nothing broke! Im 100% shore a vanos m50 would have died because the m50 non vanos has the double valve springs.

Ive done the same thing at the track, Ive got the D'Sylva chip with rev limiter removed (I dont think it is) cause I know I hit around 8k'ish RPMs and I knew it... scared the crap outta me :) But car runs find after a few occasions of this...

[Alexlind123]

Ive done the same thing at the track, Ive got the D'Sylva chip with rev limiter removed (I dont think it is) cause I know I hit around 8k'ish RPMs and I knew it... scared the crap outta me :) But car runs find after a few occasions of this...

*remembers the videos someone posted here of revving an M30 to insane RPMs*

[beetos]

The previous owner on my had the limiter set at 7k and it used to pull hard all the way up there (special cam grind, low compression, turbo etc). It ran this way for a number of years. While I can't say for deffo, I personally think the rockers are the weak link as it broke one a while back running the 7k limit but nothing else was amiss. Since then, I prefer to run to a slightly lower, 6500 with a soft cut about 6300 which it see all the time. No ill effects yet. Very impressed with my M30, it revs out sooo sweet and hard with the turbo.

[genphreak]

The previous owner on my had the limiter set at 7k and it used to pull hard all the way up there (special cam grind, low compression, turbo etc). It ran this way for a number of years. While I can't say for deffo, I personally think the rockers are the weak link as it broke one a while back running the 7k limit but nothing else was amiss. Since then, I prefer to run to a slightly lower, 6500 with a soft cut about 6300 which it see all the time. No ill effects yet. Very impressed with my M30, it revs out sooo sweet and hard with the turbo.Beetos is back... hey mate. How's that new prop shaft going now?

[beetos]

Hi mate,
Cars going great, rebuilt prop is running fine with the holden UJ and is smooth as.

Its getting an Autronic SM4 ECU next week (and maybe a CDI). The SM4 will be upgraded from Autronic with traction control (like the SM2) very soon so am looking forward to trying it out, and it has some great boost control capability. Will post dyno charts once its tuned.

Also in the process of fitting a different throttle body (the massive 90mm infinity Q45 ones) as my 4 plate throttle V8 body shafts are leaking heavily.....lot of things in the works! Will keep you updated.

[genphreak]

Sweet... sounds like she'll be well sorted. Want to get rid of the Haltech? I am about to buy an MS myself, haven't looked into that yet, but I never want to do too much to mine. One day, she'll get a little snail but it won't be a big deal, I'm planning on stock compression, MAP sensor, knock control and 8psi. I just want more drivability and realtime statisitics monitoring. No races to be won. I don't even want to tear my whole engine down as I know how good it is after doing teh head last year. (but you never know- I bloody well may do the short block properly, who knows...)

[ILoveMPower]

*remembers the videos someone posted here of revving an M30 to insane RPMs*

*Is desperately in search of this video* ;)

[Alexlind123]

*Is desperately in search of this video* ;)

http://servo.postverket.us/alex/video_00006.mp4

BTW, this is diamond77, not me.

[nixter]

dead link.

[goat128]

The harder you drive the engine, the shorter the lifespan of the main bearings and rods are going to be. Its pretty much universal, but mostly a question of how long do you want it to last. High rpms put a lot of stress on the oil in those bearings, etc. But at least you can keep the rpms below the peak hp of the engine because any higher, like the other guys said, is just a waste of energy.