Superchargers

[jrhaile]

Speaking from first hand experience, S52 cams in a m50/m52 engine don't cause rough idle, it's more like a bumpy idle :P Kind of a cool in my opinion. feels like sitting in a big old v8 and it has a rumble to it. But there is a definite difference in idle. It's not bad at all though...No one has said anything about it while in my car. Cams are a badass upgrade. I've had so many people go "do you have a turbo or supercharger" when they ride in my car. As long as your vanos system is working properly, it's badass man.

[xsperf]

^^ sorry to go off topic, but speaking of VANOS, how do you know if its not working?

and secondly, could u describe this "bumpy" idle.. is it just the difference in sound? or does the engine actually shake more?

[jrhaile]

engine shake's more and causes a little vibration throughout the car. Does your car really pickup after 4k rpms? if it does, more then likely your vanos is working good.

[///95M3]

my 95 vibrate's like crazy(stock) compared to 96 and ups and iiiiiii love it. A 95 with cams feels the same just with some extra rumble under the hood.

[larryglover@gulfviewllc.c]

Originally Posted by witeshark

IMO Adding boost without reinforcing main bearings is risky unless you drive super careful

Actually, this is not the case with M50, S50, S52 series motors. These motors have been proven to handle well over 500 hp without internal modifications. The first part to give are the rods. I know of one BMW running 740 hp without any internal mods.

[denyo77]

but either way, if you go for more power, improve the suspensino and brakes alongside

[cmill95]

k, first thing I've been working with my supercharged t-bird for a few years now so i can give you some insight into this.
if you've got a sock comp. ratio of less than 8.0-1
you should be good so far.
rods are going to be the weak link in most boosted applications above about 10LBS.
injector size should go up along with a FMU/boost sensitive fuel pressure regulator. every pound of boost you add to the intake the fuel pressure needs to go up equally to compensate for the increased resistance the fuel encounters.
cams; as close to ZERO valve overlap as possible. you don't want to bleed off your pressurized air into the exhaust system. raise your exhaust duration/lift to get the extra gasses out.
remove restrictions from the exhaust system. free flowing cats and mufflers and mandrel bends in the pipes.
heat management is key also after about 6LBS of boost. an intercooler/after cooler should be used above 8 LBS and is a necessity after 10 LBS. the heat can be immense in high boost applications. I've seen as much as 300 degree outlet temps before my intercooler! water to air works the best and can be packaged pretty small. air to air with fan is next best.
timing, get a boost retard system. possibly one with a boost line fitting. it'll back out timing to start the firing event earlier to ensure you get all out of your air charge w/o detonation.
lastly plugs, 1 to 2 steps cooler or decreased gap to prevent spark blow-out. hotter coil never hurts too.
good luck!
chris

[richobmw]

Im getting my 1985 BMW E30 323i supercharged and im hearing alot of talk about having to strengthen my internals, getting it compression tested and replacing the pistons.

My car is around 26 years of age and runs great "touch wood", if i am only planning on running stock boost (2-6psi) boost, driving on 95-98octane fuel and driving it like a grandma as in not thrashing it constantly; will this damage my motors internals??

its getting a proper professional install/tune up all on a dyno set up..?

any suggestions

when its installed their tuning it, compression testing it and replacing all the piping with an intercooler etc etc full professional installation.

thanks for the help..!