Engine remapping, the removing of rev limiters etc

[daveco]

In America, BMW released an E46 330ci with the 'ZHP' package that came with sportier cams and the redline changed from 6500 to 6800rpm.

This, it appears was enough to significantly increase the straight line performance of the car. (0-60 dropped by nearly a second to 5.4, quarter mile time by more than half a second to 14.3), despite a modest hp increase over a standard 330.

Would this shifting of the redline to 6800rpm be possible with a standard remap? The E9x 335 models started off with this engine and a redline of 7k rpm so I'm assuming it wouldn't cause any undue harm to the powerplant.

Peak power in the M54/B30 comes in at 5,900 rpm.

[E-bmw]

Increasing the rev-limiter simply means that you need to change gear less to get to the same speed, which is why it helps with 0 - 60/0 - 100 etc.

As you have already stated max power & indeed max torque are well below max revs.

[Krikkit]

If the only change was the cams on the fruitier version there's no reason why not. The power will probably be dropping off quite significantly up there mind, so it might not be of much benefit.

A lot of OEM engines are very conservative with rev limits - I suppose they have to be able to be banged straight up against the limiter from cold to pass most durability tests, unlikely to happen in the hands of a normal driver, never mind the enthusiast.

[Elliot2000]

daveco said:

In America, BMW released an E46 330ci with the 'ZHP' package that came with sportier cams and the redline changed from 6500 to 6800rpm.

This, it appears was enough to significantly increase the straight line performance of the car. (0-60 dropped by nearly a second to 5.4, quarter mile time by more than half a second to 14.3), despite a modest hp increase over a standard 330.

Would this shifting of the redline to 6800rpm be possible with a standard remap? The E9x 335 models started off with this engine and a redline of 7k rpm so I'm assuming it wouldn't cause any undue harm to the powerplant.

Peak power in the M54/B30 comes in at 5,900 rpm.

E9x cars did use the m54 to begin with, but not on the 335 - that began with the new generation engines - n54

But I don’t think losing the Rev limiter on that engine will cause any issue

Edited by Elliot2000 on Friday 1st June 12:44

[daveco]

Thanks for the advice all.

And you're right Elliott, I was fairly certain the 335 engine started with the same 3.0 unit but I was wrong.


The 3.0 feels like it has more to give near the top despite the peak power being made at 5,900 rpm so I was curious to read about the ZHP pack.

[GreenV8S]

The cam change probably included different valve springs, and valve train float may be defining the usable rev range. Depending how safe the engine is, the consequences of valve float could be catastrophic or negligible.

[daveco]

GreenV8S said:

The cam change probably included different valve springs, and valve train float may be defining the usable rev range. Depending how safe the engine is, the consequences of valve float could be catastrophic or negligible.

So would you recommend leaving the engine as is and not remapping for that extra 300/500rpm?

[GreenV8S]

daveco said:

So would you recommend leaving the engine as is and not remapping for that extra 300/500rpm?

I recommend not using your engine to find out whether that extra 300/5000 rpm is safe, unless you are comfortable with the risk of damaging it. If you can find somebody who has already tried this with a similar engine, or can find the specs for both variants and confirm there are no other changes to the valve train or bottom end, then you'd be good to go and just need to decide whether it's worth the cost.

[227bhp]

There is no point in revving an engine when there is no power left to be had, AKA 'flogging a dead horse'.

[Kccv23highliftcam]

Agree with last two posters.