318is Engine Mods

[Dan320is]

Having owned my IS since march I think its time for some performance mods.

Anyone with an IS suggest anything?

Getting it 'chipped' has been mentioned but surely this is only done to make the most of proper engine mods like cams etc?

And what is this idea of removing the throttle body heat plate thing?


Cheers

[maxfield]

ITG.
BBTB.
Cams.
Remap.

Not sure about exhaust as the standard is supposed to be the best for power.

[keggy]

i found this online it may be of help
Modifying the M42 318iS Author: Stuart McHenry

This is a compilation of things that are necessary to get real performance out of the M42 engine that you use in a street/auto-x/mild track use car. These are items that will improve the cars performance and not sacrifice any low-end torque, which you want for street driving. These are all pretty much "bolt-on" mods, using the engines factory internals. If you want your 318iS to really fly on the street, these are the things you need to do:

Computer chip - This is a very basic and inexpensive modification for your car. Chips usually run about $200-$300 and are very easy to install. A chip on a stock M42 will bump the horsepower to about 145 (from 135) at the peak. The low-end torque is increased as well to improve everyday drivability. Though the real improvement comes at the top end; the chip widely increases the power band on the M42, from 4600-6000 to 4500-6700. I recommend Jim Conforti chips, as they are unarguably the best on the market for this motor, at a good price as well. On a side note, you will find the M42 makes a very distinctive "howl" from 6700-7200 rpm that reminds you that you're driving an honest-to-God BMW.

Flywheel - A major problem with the M42 was that it had BMW's 'dual-mass' flywheel; yes, it weighs almost twice as much as a 325i flywheel (as the name would suggest), at 28.5 pounds. This is a big problem and absolutely kills 1st and 2nd gear acceleration. Ever wondered why your 318iS's 0-60 was so slow? Well, the flywheel is one of the reasons.
There are 3 options to fix this: 1) use a 325i flywheel/clutch or 2) buy an aluminum flywheel for your M42's clutch, and 3) an aluminum flywheel for using the 325i clutch. Buying an aluminum flywheel for the M42 runs about $500-700 but is very light, and requires no modification to be fitted. M42 aluminum flywheels are about 12 pounds, and 325i aluminum fly's are about 8 pounds. The 325i flywheel requires a few other modifications to be fitted in the 318iS. Here's what you need: 325i flywheel, 325i clutch, 325i pressure plate, 325i drive-pinion for the starter motor, and a â€Ëa78-'83 323 throw-out bearing. Replace all these with the 318iS parts and it bolts right together. After all is said and done, your 318iS will have a LOT better acceleration in the first few gears, and deceleration will take place much quicker, which helps on the street and in the auto-x.

Rear end gear - The 318iS is equipped with a 4.10 limited slip from the factory, but you can do better. The desired gears out there are the 4.27 and the 4.45. You will find the 4.27 in E30 318i convertible 5 speed's and the 4.45 is in E36 318i automatics. The 4.45 is a wicked, wicked street gear but will stick your RPM way up there on the highway. The 4.27 is a good compromise of performance and everyday use. It should be known that to make a 4.45 work, you have to swap the gearset into your E30's differential, or find an automatic 318ti, which has a 4.45 and also has trailing arm rear suspension! So the E36 318ti 4.45 bolts right onto an E30, though finding an automatic 318ti with LSD may be difficult.

Adjust the cam timing - You know how on the E30 M3 you have to buy a $300 kit with adjustable cam sprockets to tune your cam timing? Not on the 318iS! The M42 is equipped with tunable cam sprockets from the factory. So pull your Cosmoline covered valve cover off and with the proper tools you can tweak your intake and exhaust cams up to 6 degrees +/- to provide more top end horsepower or more low end torque. See, you don't have to blow a grand on a set of Schrick cams to make your M42's cams a little hotter. The best setup is to adjust the intake cam to 5 degrees (advanced) and leave the exhaust cam alone. I would recommend having a shop do this work.

Muffler - The 318iS is equipped with a very free flowing exhaust manifold and center section with 2.25" stainless piping. The bottleneck in the system is the muffler. Thee are a few options for this. The first is a cat-back system, which replaces the piping and boxes behind the catalytic converter. Supersprint makes an excellent cat-back system that runs about $400. You can also simply replace the muffler. There are a variety of mufflers on the market but there is one that is very inexpensive, sounds great (not too loud, but throaty), and fits an E30 very well - it is made by Walker-Dynamax and is called the "Super-Turbo" muffler. It is available from Summit Racing at the price of about $40. We have had great success with these mufflers, and even use them in 3" size on our E30/S50 cars.

Intake system - The 318iS stock airbox works well, but a cone filter setup works better, but only if you have a well-built heatshield! Get a large K&N setup with the AFM adapter and all. Go to Home Depot, buy some Reflectex and build a "cool-air" system by cutting and fitting a heatshield. It is worth it in the end. While you are working on the intake, get the secondary plate of your throttle-body bored out 3mm to 57mm. This will make a difference.

[Kos]

in this months Total BMW magazine, you'll find an feature on my old IS, all my mods are there , it was making 162 bhp and 149 ft/lb torque

other than that, an alloy flywheel from JB racing ( available from power 4 peanuts ) the fly whell will by like giving your car 20-30 bhp through the rev rannge ( it doesnt actually give you extra power )

[sportscarfan]

in this months Total BMW magazine, you'll find an feature on my old IS, all my mods are there , it was making 162 bhp and 149 ft/lb torque

other than that, an alloy flywheel from JB racing ( available from power 4 peanuts ) the fly whell will by like giving your car 20-30 bhp through the rev rannge ( it doesnt actually give you extra power )

Available from power? Who are they? Have they got a website? I would be interested to have a look!

[Chris-W]

www.power4peanuts.com

[Kedge]

And there was me thinking he meant it was cheap haha

[Dan320is]

mmmmm.....got me thinking now. I shall have a look at the timing idea.

Does anyone know what the benefit is of removing the heater plate from the throttle body? Or what is does?

[tomtomiS]

And there was me thinking he meant it was cheap haha

yea right mate, i was thinking it was gonna be not too expensive, but custom flywheels etc, yikes!!

[Kos]

And there was me thinking he meant it was cheap haha

yea right mate, i was thinking it was gonna be not too expensive, but custom flywheels etc, yikes!!

you could spend £500 on cams and the same a again on a re map and exhaust and it will no be as good as getting one of these fly wheels

trust me

[keggy]

the 325 flywheels fit with minor modifitcation. might not be as god as the lightweight alloy flywheel but certainly alot cheaper

[Kedge]

How much of a noticeable difference does it give Kos?

[Kos]

the simplest way to explain it is this was,

your doing 60 mph , in 4th gear and put your foot down it feels like you've dropped it down a cog to 3rd

[tomtomiS]

i spose it would give the feeling of bettder throttle response?

[OBs]

Does anyone know what the benefit is of removing the heater plate from the throttle body? Or what is does?

Heats the air going in to the throttle body, engines run better colder the better

OBs

(Book marked for later!!)

[Kos]

its fast and hard revving, and an IS having a strong bottom end will take the abuse, moving your red line to 7250 as well will make it quite a car, especially if re mapped like mine was

the owner of mine is fitting a 4.27 LSD and one of these fly wheels at some stage, think he's looking at cams as well. this set up will take it to 170 bhp with more mid range grunt, a shorter diff will make it quicker to 100 mph, and the flywheel will make it very very responsive.

i bet it will destroy 2.5 day in day out and be a real track day weapon.

the day i build a track toy its going to be an IS set up just like this

[Kos]

Does anyone know what the benefit is of removing the heater plate from the throttle body? Or what is does?

Heats the air going in to the throttle body, engines run better colder the better

OBs

(Book marked for later!!)

its makes it less restrictive as well

[tomtomiS]

well kos i will take that very literally then and invest in one after ive bought a new headunit, besides mine also got a 3.64 diff in it which needs sorting out at some stage soon

[Kos]

well kos i will take that very literally then and invest in one after ive bought a new headunit, besides mine also got a 3.64 diff in it which needs sorting out at some stage soon

with that diff in it with the light wight fly wheel it will perform very well, and probably give you a top speed of 135mph

try it out first then swith to a 3.91, more practical for a road car, but on track top speeds not that vital, on the road however economy and lower rpm's for motorway crusing will be better

a few zoners have fitted 3.91 "large case" diff to their IS's as they are stronger and are easier to find in LSD forms, and they dont really have negative comments about loosing performance on a standard set up

[tomtomiS]

with the 3.64 it pulls to 99- 100 mph in 3rd gear and is good for the economy. its got a viper chip which i hope compensates for the acceleration lost by having a lower geared diff. further to brianmoores comments about performance exhausts i will probably leave mine standard. by the way what sort of money am i looking at for different cams?

[Kos]

no idea about the cams, not looked into it, dan-318is should know though

exhust on the IS is pretty good, i just changed the back box for a more spoty noise !!

[Kedge]

Just got a price for a price on a JB flywheel from power4peanuts, £404 + VAT and £15 P&P.

Has anyone found a better price at all?

[maxfield]

Just got a price for a price on a JB flywheel from power4peanuts, £40 + VAT and £15 P&P.

Has anyone found a better price at all?

That's a very cheap price if you ask me!

[Kedge]

Typo corrected

[maxfield]

Thought it was a bit cheap...

Still a decent price... they're about $700 from the USA.

[Kedge]

Well when you add it all up it comes to £489.70, so with the strong rate of the pound i was just wondering if anyone had found them any cheaper either from buying straight from the states or another stockist over here.

[Bob_S]

I can't help but think (from my limited knowledge) that some of those mods are utter bullpoo!
here are my points feel free to correct me though!

lighter flywheel? I though it was dual mass so that the torque was higher bigger rotational mass on the outside, momentum etc etc?

K&N in my experience all it does is suck in all that lovely hot air trapped under the bonnet?

adjusting the cam sprockets - I thought all this did was move the power band about and no real increase was to be had bar the fact that the 5degrees made it a little more responsive up the top end of the rev range?

just my views and would like to be corrected if I am wrong

[Cabrio]

Anyone considered lightening the existing flywheel!..do know someone planning to see if it is possible for himself

[MrDazzle]

lighter flywheel? I though it was dual mass so that the torque was higher bigger rotational mass on the outside, momentum etc etc?

K&N in my experience all it does is suck in all that lovely hot air trapped under the bonnet?

adjusting the cam sprockets - I thought all this did was move the power band about and no real increase was to be had bar the fact that the 5degrees made it a little more responsive up the top end of the rev range?

Changing the flywheel mass makes no difference to the power output of the engine, it just changes the rotational inertia of the car's drivetrain. It's just like removing weight from the car really, 'cept removing 1kg from the flywheel makes much more difference that removing 1kg of 'normal' weight.

The K&N in question isn't a cone filter like those beloved by Max Power, it's a less restrictive filter that goes in the existing air box. It means you keep the existing air intake behind the headlamp.

I am the owner of Kos' old iS, and like he says the engine is rather special. Unfortunately though, it's slowly developing a cam chain rattle that makes me reluctant to rev it! Need to get that fixed!

I reckon the 4.27 LSD will transform the car quite well, and an ally flywheel will suit it perfectly, it's such a revver...

Cams, you're right really...

[Bob_S]

Sorry I didnt realise thats what he meant with the filter.
There was a thread/web page where someone compared the K&n green cotton gen bmw etc panel filters in a very crude method and the BMW oem one was less restrictive than the supposed better K&N one!

4.27 does make it accelerate like a weapon I had a bbr star chip in mine and freak me it flew for an is and banged the limiter at 135 a couple of times on the autobahn >:)

ah right I may have to find an m20 flywheel then I thought it helped with torque figures being heavy on the outside, bucket of water thrown around but none falls out theory?