M42 Questions for FI

[Omi]

Haven't decided which to go for yet, but need to clear up a few things before I go any further.

-Will I benefit from a knock sensor?

-Does the current MS system do fuelling and ignition or just fuelling?

-I was thinking w/b O2 sensor, MAP sensor and Throttle Position Sensor, rather than switch. - Anything missing?

-How much boost will I get away with before pre-det on a stock M42?

-10.5:1 CR is quite high, isn't it? Any way of lowering this? Engine is being rebuilt first, so can I take some deck height away?

-M42 injectors (IIRC) are different to every other BMW Injector out there... What are my fuelling options?

Anything else you think is relevant, let me know...

Surprised more people haven't done this, to be honest. - Whole rotating mass in the M42 is forged and should handle a bit more torque fairly well![/list]

[Demlotcrew]

Yeah the clutch/gb/diff wont.

Andrew

[Omi]

Well, I've got 2 of each spare, so I'll take my chances... You bloody pessimist! - Brand new clutch on the rebuilt engine and it's not too much hassle to find an uprated one. Plus I'm using a large case 3.91 LSD.

[Jon_Bmw]

Something you might be interested in, its for the m44 engine but "apparently" can be adapted to the m42.

I don't think you'll benefit from a knock sensor, you have to be pretty stupid not to realise when an engine is detonating, which is all a knock sensor prevents.

Ms2 does fueling and spark

Yes get a wideband 02 sensor, Ant and Mark are having good results and easier tuning with theirs.

Please lower the compression ratio or it will detonate, i would think that if you didn't you would struggle to get over 8 psi.

Not sure about injectors, don't know the engine well enough, but you will need bigger or additional injectors for sure

Jon

[e30_Turbo]

Ms2 does fueling and spark

Yes get a wideband 02 sensor, Ant and Mark are having good results and easier tuning with theirs.

Please lower the compression ratio or it will detonate, i would think that if you didn't you would struggle to get over 8 psi.

Not sure about injectors, don't know the engine well enough, but you will need bigger or additional injectors for sure

Jon

Ms1 with V2.2 and msns-e will run both fuel and sparks although you'll need the extra hardware for the sparks.

Widebands are a must for tuning, especially turbo's, although if you have it tuned for you, the sensors they have on a RR are much more detailed and accurate.

Injector wise, once you have a power band in mind you can work out what injectors you need.

Rough example, I have tripled my injection capabilities to get just over twice the std power, well I have enough juice to fuel it if I ever get it that high std is 149cc/min, mine are 440cc now.

hth, Mark.

[Jon_Bmw]

oops my bad Mark thought it had a a 2 in it somewhere.

[Turbo-Brown]

You don't absolutely have to lower the compression, even at 10.5:1.

The Mi16 has a 10.5:1 CR, but we're only planning to run 5psi which theoretically should be good for about a 34% power hike. The Mi16 makes 160bhp from it's 1.9 litres so the 5psi should see it past 200bhp with any luck.

Not sure knock sensors can be retro fitted to an engine as the vibration paths through the block need to be designed in i.e. you can't necessarily rely on a knock sensor that's just bolted on somewhere.

[Omi]

Ok, I'm going Turbo. *maniacal laughter*

Going with a throttle position sensor, O2 w/b and manifold air pressure sensor. Probably stick with wasted spark ignition, pick up pulses from the stock crank pulley sensors. Aftermarket knock sensors are vary handy and can be adjusted in some cases to disregard valvetrain noise. M44 has one fitted and the block is virtually identical, so that's where it'll fit!

Blow off valve just before the inlet tract, discharging to atmosphere, small intercooler behind a modified valance.

Probably S50 injectors, which I'm assured will fit... Would be nice to have a better inlet manifold, but haven't thought that far ahead.

MS2 Standalone... Will I have any problems? ECU does more than just timing and fuelling, so will that just be left in situ, but ignored by the engine?

I'm not going for hideous power-gains... - I'd like to see a little over 200bhp at the tyres. Forged internals are good for at least that, and apparently the stock M42 pistons should be good to 100bhp per cylinder, as other people have used them.

7k rpm redline, according to the specs it's all balanced to well over 8, but I'll be getting that checked during the rebuild.

My biggest concern is the compression ratio and whether I can lower that somehow to make it easier to boost without detonation.

[jaistanley]

Many people in America are running forged pistons and I've e-mailed companies to see if you can get them to this country. Looking at 4-500 notes but it'd solve loads of problems. Do it once, do it right and all that.

With new rod bolts and a new front pulley it'll do 8K RPM all day long apparently. The front pulley/vibration damper is the limiting factor on revs according to the american forum boys. To solve this I've been looking at designing a new solid front pulley with the Ford tooth pattern so running megasquirt plu edis would be really easy and look factory. The engine would need dynamic balancing to prevent excess vibration.

Flywheel from a 325i is a lot lighter and the clutch is known to be good for the 2.7's of this world. A few other parts are needed but it'd give the engine a lovely throttle response, especially with light pistons.

The solid lifters from an M3 Evo e36 fit too for the added revs and controll at high RPM. I guess the injectors would too. You could go mad and make an adaptor plate and use the throttle bodies (a friend of mine has some and I've considered it, they look perfect for the job), thats pretty mad though.

The head and cam design of the M42 seem to cry out for forced induction...

DO IT FELLA!! (I'm too skint)

Jai