Author Topic: Engine tuning M42B18 (Read 30953 times)

PerTore · « **on:** January 16, 2012, 02:44:10 PM »

Hi.
I have a 90" 318is rally car that I could use more power in. I have dismatled the engine for a check, and it looked good inside. I'm going to fit new pistonrings, but the bearings looks brand new, so they will do for now. I'm thinking about a new set of cams, any good suggertions?

I'm also hoping to use the standard FI, maybe fit bigger injectors, and turn up the fuel pressure. Will this work?

Any other ideas on how to get more power, will be appreciated.

No turbo or supercharger are allowed.

(sorry for my "Petter Solberg-english". I had, like him, my mind on rally when I was in school)

bmwconnect · « **Reply #1 on:** January 16, 2012, 02:55:34 PM »

I can do a custom or standard chip for your setup

Contact me at midnight-tuning@rogers.com

DesktopDave · « **Reply #2 on:** January 16, 2012, 03:52:44 PM »

A chip would really wake the car up, I'd bet. Likely that's the best bang-for-your-krone. Single mass M40 clutch and a higher ratio diff (like a 4.1 or so) are a big help as well. Dropping weight is another easy mod...eliminate all the insulation, the spare tire, CF hood, patch up the sunroof, racing buckets, etc.

Might want to double check the bearing clearances & fit a full-radius thrust bearing. We only got a half-shell (an M50 has the right one IIRC). There's a thread on here somewhere about it. While you have it apart I'd be tempted to measure the oil pump, replace a lot of gaskets, change the cam gears, idler gear, worn timing components and the water pump.

Given that you can't use forced induction, I'd spend some time porting that head, removing the throttle heater and the mess under the intake if possible & fitting a cold-air intake. Degree the cams, insulate the intake manifold, wrap the exhaust, install a wideband O2 sensor, and use the thinnest fully-synthetic oil you can get away with in the entire powertrain.

If you're really looking for more power, might be worth it to find an M47 crank for longer stroke. It looks stock, you'd need a really good mechanic to note the difference. IIRC S52 pistons are the best combo with these...

PerTore · « **Reply #3 on:** January 17, 2012, 03:00:07 AM »

Stroking is not allowed, and it will be checked from time to time at scrutening. The car already have the 4.1 diff ratio. And I will of coure change all gaskets while I have it apart. CF hood is not allowed, and the weight is already on its minimum.

MikeDE · « **Reply #4 on:** January 23, 2012, 12:27:13 PM »

Quote from: DesktopDave;109646

A chip would really wake the car up, I'd bet. Likely that's the best bang-for-your-krone. Single mass M40 clutch and a higher ratio diff (like a 4.1 or so) are a big help as well. Dropping weight is another easy mod...eliminate all the insulation, the spare tire, CF hood, patch up the sunroof, racing buckets, etc.

Might want to double check the bearing clearances & fit a full-radius thrust bearing. We only got a half-shell (an M50 has the right one IIRC). There's a thread on here somewhere about it. While you have it apart I'd be tempted to measure the oil pump, replace a lot of gaskets, change the cam gears, idler gear, worn timing components and the water pump.

Given that you can't use forced induction, I'd spend some time porting that head, removing the throttle heater and the mess under the intake if possible & fitting a cold-air intake. Degree the cams, insulate the intake manifold, wrap the exhaust, install a wideband O2 sensor, and use the thinnest fully-synthetic oil you can get away with in the entire powertrain.

If you're really looking for more power, might be worth it to find an M47 crank for longer stroke. It looks stock, you'd need a really good mechanic to note the difference. IIRC S52 pistons are the best combo with these...

What Dave said....btw I have a nice 4.27lsd available, pm me if ya like.

PerTore · « **Reply #5 on:** January 24, 2012, 10:50:05 AM »

Thanks everyone. I've just ordered A set of 269dg Cat Cams and a matching chip from Motor Nord in Sweden, and a new set of piston rings and bearings is fitted, along with cylinder honing I think this will do for now. Anyone with a qualyfied guess on what power I'll be looking at?? I'll take it to the dyno afterwards, mostly to see if the mix i right, but I'm also curious on the power, of course...

enildeR · « **Reply #6 on:** January 27, 2012, 09:03:31 AM »

There's no need for cams. Your stock cam gears are adjustable. Search the forums. I believe there are a couple threads that mention the adjustments to be use. Combine that with the Mark-D chip, and you'll have a considerable amount of gain.

Have you done the electric rad fan conversion? Have you taken out the A/C hardware? Did you remove power steering?

Since this is mainly for track, I have to ask: have you installed adjustable shock mounts in the front/rear? A properly adjusted suspension can be worth considerable time on your lap, unless it's a track meant for cars with power, i.e. long straights.

Back to the diff. Are you running the stock bushing, poly, or a solid plastic one? If stock, have you checked it lately? Might make a diff in the longevity of your next diff. Also, is your guibo still good?

PerTore · « **Reply #7 on:** January 28, 2012, 03:51:47 AM »

Yes, electric fan is fittet, no power steering, no A/C. Rally springs and shocks is fitter, I've done a few rallies with it, and it handles great. All bushings are stock, and they are in great shape. Rallies in Norway mainly runs on "bad" roads, with potholes, bumps and jumps, on gravel or snow/ice surfaces. I belive that rubber is the best materials for bushings etc., plastic will be too hard, and cracks in mounts in chassis often appear on the cars that runs with plastic bushings.

What is a guibo??

Geoff · « **Reply #8 on:** January 28, 2012, 06:43:26 AM »

guibo-generally accepted term for the rubber do-nut BMW uses on the driveshaft instead of a steel u-joint:)
Geoff

PerTore · « **Reply #9 on:** January 28, 2012, 12:52:07 PM »

Ok. Thats what I thougth.

wazzu70 · « **Reply #10 on:** January 29, 2012, 05:17:21 PM »

Quote from: enildeR;109837

There's no need for cams. Your stock cam gears are adjustable. Search the forums. I believe there are a couple threads that mention the adjustments to be use. Combine that with the Mark-D chip, and you'll have a considerable amount of gain.

Have you done the electric rad fan conversion? Have you taken out the A/C hardware? Did you remove power steering?

Since this is mainly for track, I have to ask: have you installed adjustable shock mounts in the front/rear? A properly adjusted suspension can be worth considerable time on your lap, unless it's a track meant for cars with power, i.e. long straights.

Back to the diff. Are you running the stock bushing, poly, or a solid plastic one? If stock, have you checked it lately? Might make a diff in the longevity of your next diff. Also, is your guibo still good?

The cam adjustment will only be a good option if the rules do not allow anything but factory camshafts. The gain from advancing the intake came will be a slight bump in mid-range torque (which will be good for rally). Even then, its not the best option.

My recommendation would be to look at catcams.be as they have many grinds and can even do custom grinds.

If you get some reasonable cams you will need a custom tune...the markD will not be enough for compensation to get full benefit.

Which part of Norway are you from? I have spent some time there on holiday.
Tusen takk

PerTore · « **Reply #11 on:** January 30, 2012, 10:01:45 AM »

Thats exactly what my setup will be. 269dg cat cams, and a matching chip from motor nord in sweden.

I'm from the south/east of norway, 1 hour drive west from Oslo

wazzu70 · « **Reply #12 on:** January 30, 2012, 11:55:06 AM »

That sounds like a great setup! Looking forward to seeing a dyno chart!

I took the train from Bergen to Oslo. I also went from Oslo to Lillihammer and all around. Fun trip, wish I was back there now!

PerTore · « **Reply #13 on:** January 30, 2012, 01:32:52 PM »

Thats a great train ride!

I hope to get the parts and have it assembled during next week, so a dyno run is in the nearby future

Any guess what power I'll be looking at??

wazzu70 · « **Reply #14 on:** January 31, 2012, 11:04:39 PM »

Hard to say. It depends a lot on the tune!

One other thing to consider is an exhaust header. The factory tubular manifold is decent, but if you are racing you want all you can get. I have seen people get much better results with a proper set of long tube headers. This will also help give you some lower end grunt, which you want in rally.

Supersprint makes some headers and there are some cheapo copies on ebay. Personally I would pay for the real deal, especially if you can find a set used!