e36 m42 tuning options?

[318iSeccosse]

Hi,

I currently run a 1994 e36 m42 coupe as a daily driver- so far, over 12000 miles in 9 months, with very few repairs needed:D

Car has returned an average of 39.67 mpg (imperial), circa 33mpg (US), with myself and the girlfriend driving.

The car has been good fun (so far, 1 trackday, and 1 European trip, including Swiss Alpine Passes and the Nurburgring), but I feel the engine could be better..


Firstly, I find the power delivery very "Peaky" (yes I know its a 16v 4pot!) compared to the 6 cylinder BMWs I own.

I know the m42 has good torque and HP, but its a bit high up the rev band to use - the car mainly sits on the motorway at 70mph, turning approx 3000rpm.


So, I'm looking to improve the following things

1.Bottom end torque (1500-3500rpm range)

2.Improved Throttle Response

3.More HP- preferably in the 2500-4000rpm range, rather than up past 5000rpm.


I know this is probably counter intuative to you 16v fellows, but thought I'd ask anyways..

All hints/tips/suggestions/guides are most welcome!

and no, I'm not gonna just buy an m50/52'd car..:p

[DesktopDave]

Differential ratio is an easy & cheap way to move the power band further down the scale.  It doens't do anything for the motor, but say a 4.45 nudges everything a few hundred RPM lower.  I went the opposite direction myself...3.73 for me!  Gives slightly better economy instead.

MarkD's 93 octane chip is legendary for these cars as well.  They seem pricey (~240USD on sale) but are worth every penny.

[318iSeccosse]

Differential ratio is an easy & cheap way to move the power band further down the scale.  It doens't do anything for the motor, but say a 4.45 nudges everything a few hundred RPM lower.  I went the opposite direction myself...3.73 for me!  Gives slightly better economy instead.

MarkD's 93 octane chip is legendary for these cars as well.  They seem pricey (~240USD on sale) but are worth every penny.

Ideally I'd like more lowdown Torque so I can turn a longer diff (like a 325i 3.15 diff) at the sort of RPM it'd be doing on a motorway..

As for Chipping- the car is a UK model, and mapped to 91 RON- pretty happy with that TBH.

I'm more interested in Mods/changes that can be done to enhance the operation of the engine in my chhosen powerband..if that makes sense?

Thanks for your post- glad to see  I'm thinking along the right lines with the Diff swap:D

[318iSeccosse]

Thanks for the reply Dave,

I'm looking at changing my diff to a 3.15 off a UK 325i, so I can get the Cruising RPMs at 70mph down.

The 3.45 in the car is very very short.

I'm also looking at changing the Cam timing to generate more lowdown torque- enabling me to turn a longer diff.


As for chipping, in the UK where I'm based, the cars are mapped for 91RON from the factory, and the normal petrol is 95 RON, so I dont see a US chip working unfortunately.

I'm looking more for physical modifications that could be carried out to improve torque and drivability below 4000rpm...

does anyone else have any suggestions?

Thanks

[DesktopDave]

Mark does offer a 91 octane chip, but only for the e30.  That's 95 RON, right?  It'd be an easy solution...but even his chip doesn't offer much until over 4K RPM.  There are stroking options with the M47 diesel crank and custom pistons, but that's not cheap work.  The Downing Atlanta supercharger is another option, but they're pricey and rare.

Did you think about a single-mass flywheel?  I haven't done it myself, but a lot of members here have, and they rave about it.  Being in Europe, you'd ahve access to the correct parts instead of cobbling together the M20 FW & e21M20 TOB we have to use over here.

I'd be tempted to degree the cams, like you suggested, only if I had access to a dyno.  I've heard mixed results from that method.  BMW did a good job tuning the motor, it's difficult to improve substantially on it.