m42 build

[318isteve]

hay there planning my m42 rebuild, and have a few questions:
what will i need to change/replace to rev out to 8000?
what engine's can i get solid lifters from?
and is a MAF conversion worth doing, abit confused after reading several different threads?
is it worth lightning the internals pistons rods cranks etc whilst they are at the shop getting balanced or not really?
thanks in advance guys any help will be much appreciated!:)

[swiss318is]

hey... first MERRY CHRISTMAS
your budget? low.. or high?
1: to rev to/over 8000rpm, the community is split in two half.. the ones who says yes, it works with the hydros and the other who says no! i am in the second one.. :-) they will pump up.. and then you receive a fresh salad of broken valves...
for the rest.. balance the crank, lighten the flywheel, balance and lighten the rods and pistons.. like that.. it should be possible to run to 8000rpm.... BUT i am not sure about the oilpump and the waterpump..so i think its only for short accelerations then for long highway runs..
2: solid lifters! use the search button.. we discuss that already several times... NO solid lifters from other engines available.. only lighter hydros from vw/ford/audi
3: MAF.. no.. why? do you change the ecu?cams?etc...
4: YES! balance everything in the engine for a smooth idle and run of the engine.. and you will gain a few hp, 2 or so... OR you change the internals to H-beam rods and new rods

SOLID LIFTERS.. i found some for the m42 engine.. but the set will cost you around 1000.-$

[swiss318is]

btw.. have a look on my thread "swiss 318is" from time to time... i am currently building a sick street engine.. a small s42

[crazzy_hippo]

I think 8K RPM is going to be tough for hydro lifters. Even MM's motor is limited to 7700 RPM with hydro lifters. You will also need to replace the springs with stronger as valve float is likely to occur with stock springs.

MetricMechanic to sell solid lifters for M42s but the price is......hoho.....you can buy an engine with that amt and still have savings left.

Btw, you will need to replace your cams if you are revving to 8K RPM. The stock cams are optimised for low RPM and they become a restriction instead.

[318isteve]

Merry Xmas!
unfortunatly the budget is low i am a young student.
as nice as a valve salad sounds.. not quite what im after,
but basically to reliably do it i need solid lifters a new water and oil pump, and a nicely lightened and balanced bottom end. what bmw motors come out with solid lifters m50...
what is the advantage of H-beam rods?
MAf conversion? i am going to keep stock ecu but chip it and yes hopefully get the cams reground also, will i notica an increase in power or throttle response with a MAF conversion?
$1000 ouch...

[crazzy_hippo]

Merry Xmas!
unfortunatly the budget is low i am a young student.
as nice as a valve salad sounds.. not quite what im after,
but basically to reliably do it i need solid lifters a new water and oil pump, and a nicely lightened and balanced bottom end. what bmw motors come out with solid lifters m50...
what is the advantage of H-beam rods?
MAf conversion? i am going to keep stock ecu but chip it and yes hopefully get the cams reground also, will i notica an increase in power or throttle response with a MAF conversion?
$1000 ouch...

Only the Euro S50 motors come with solid lifters. US S50 and all M50/52 uses hydro lifters.

For H-beam forged rods, they are lighter than stock. Check out eagle rods for some of the finest rods out there.

regarding MAF conversion, it is not possible with stock ECU. You will need at least a piggyback ECU to work with MAF. But from what I have read, its not really worth spending the money just for MAF, our "barn door" sensor is not that restrictive by nature and you will hardly get any improvement.

I too have been contemplating for a 8K RPM motor. But after some research and asking, its not worth the effort and it cost too much. Power gains will be minimal as well compared to going turbo/SC.

Seriously, if you are after power gains for your M42 at minimal cost, a turbo is the best option. Else its rebuild and go for M47 crank and custom pistons.

[papercutout]

You'd probably benefit from setting your aimed max rpm to 7500 (which is still high...) instead of 8000. Whats the real benefit of hitting 8000rpm unless you're having a race tuned engine that'll maximise the potential? Guaranteed that if you do above mods, if you do hit 8000rpm you'll be well past peak power and will have wanted to have changed up by then.


Whatever you do, have fun!

[1990s14]

i agree with the comments above regarding an 8k engine, you are getting into competition spec. parts

If your budget is low, avoid solid lifters, perhaps use lighter vag hyd lifters.  The most aggressive cams you will be using will keep the revs under control. With this setup you could also retain your AFM and TB to keep the cost down. With a good remap we are getting 146 at the wheels with a similar setup

imo reground cams wont perform as good as billet catcams(.be) for example due to lack of flesh on the lobes

[318isteve]

cheers everyone for all the info, decided i will keep the AFM and not worry about solid lifters etc, start looking around for some h-beam rods and maybe some aftermarket cams.
yea going to look down the turbo route after alittle bit as insurance will be horrendous at my age. anyone found reasonable gains from intake porting or throttle body boring?