After having a good chat with @m44lee via PM, I thought it would be a good idea to make a thread, sort of like a 'Handbook' (if you will), in regards to what tuning possibilities & performance upgrades that can be done to 4-cylinder BMW's in the M4x range.
This thread will focus mainly on M40, M42, M43, M44 engines, as these are the 4_cylinder engines used in Z3, E30, E36, & also E46 (up to 2002)
This thread is always updated, so if you know some mods not listed below, please do share them & i'll update this post
BTW, if you're here to put people off by saying "Get a 6_pot & be done with it!!" nonsense, do that in your own thread. Understand that some people like to be different and it is after all, their car...'not yours'. Let's not give Mods a hard time cleaning this thread.
So anyways, prepare for a very lengthy read!....
TurboChargers (Forced Induction):
These engines can handle upto 8 psi of boost, on stock parts without a remap, as is proven on my set-up, however, with the additional tuning & upgrades to the engine, the boost can be increased to 20-25psi under certain circumstances...
However again, 1-15 is more like the threshold for the sake of engine stability.
Adding the turbo isn't too hard, and usually involves:
- Finding the right size turbo, make sure it can run from 4-15 psi maximum, for engine stability reasons
- Making sure it has a "Internal Wastegate" ('external' ones will mean extra unecessary pipe work in a tight engine bay!)
- Speaking of internal wastegates, that would be the best way to increase/reduce boost by adjusting the rod itself.
- Also don't forget the physical dimensions of the compressor affect WHERE you will place it.
Take a look at the image below:
- I must add that regardless of where the turbo is placed, the exhaust manifolds will need fabrications
Speaking of fabrications, you have basically have a few options:
- Custom = This is usually common on most set-ups, basically a 'flange' is fabricated to mount the turbo on to the exisiting OEM manifold
- Pre-Fabricated For M42/M44 = There is a company in the US called "OBX" that sells ready made turbo manifolds, usually for T3/T4 turbos.
- Alternatives for M42/M44 = There's a few 6_Cylinder turbo manifolds, you can get those & cut the last 2 sections, until it becomes a 4_cylinder manifold, it will still fit on the car regardless. This has been done countless times at the people overseas.
- Pre-Fabricated For "M43" specific = There's a German company called "HG-MotorSport.de" that sells ready made manifolds for "M43" engines.
- Alternatives for M43 = I must say this is NOT proven, but there are some reports online, that a turbo manifold from a Diesel "E36 318TDS" will fit M43, since the TDS has a similar manifold design, judging by the bolt patterns. So basically it's a gamble!
- So, what about the M40 Engines? = So far, there isn't a company that makes bolt-on kits for M40 engines, so basically this will be a Custom Job.
Just to summarise, the readily available kits look like these:
So which turbo? = Garrett is always the best choice, instead of unknown chinese brands. So therefore I won't suggest others!
Which model then? = There's so many models of Garrett turbos, the list would be long! - But, most common turbo's used in E36's are "T25" "T28" "T3/T4"...
What about JunkYard turbos? = You can find turbos from cars such as Saab, BMW Diesel engines, Honda, Nissan, Toyota etc... However, because this is a used unit, you better aim for a 'low mileage' turbo and ensure it isn't physically damaged otherwise, it wil cost a lot of money to rebuild the compressor.
Okay, what sort of BHP can i expect from a turbo = With the right tuning & upgrades to other parts of engine, you can expect 200 - 235bhp
What If i want to run a turbo on stock internal engine parts = If you're running a turbo without engine upgrades with an 'un-tuned' ECU and WITHOUT 'StandAlone' Management, then expect 160-170bhp maximum!
What's the shopping list for a turbo kit ? = Well, a turbo set-up consist of the following:
- Garrett Compressor
- AFPR (Auxilary Fuel Pressure Regulator)
- Blow Off Vavle or Recirculating Valve (Recirculating means un-needed air recirculates back to the turbo, keeping it spooled)
- Manifold Kit or Custom welded manifold flange
- Optional: StandAlone Tuned ECU
- Optional: Larger Injectors
SuperChargers (Forced Induction):
In regards to to SuperChargers, the same rule applies for the amount of boost the car can handle. So to summarise this part, 8 PSI is fine, 15 is the maximum before the engine becomes unstable, 20 psi is extreme but prepare to buy another engine afterwards.
Are there any supercharger bolt on kits ?: Yes bolt on kits exist from the likes of DASC & GKDMotorSports:
DASC: DowningAtlantaSuperCharger kits have been discontinued a very long time ago, so the only way to get hold of this kit, is buying it USED from someone else. So prepare to search the whole interweb for one!
GKD: Luckily this company is based in Kent, UK. Their kit is available on eBay, HOWEVER, the kit doesn't come with a compressor, so you need to get hold of the compressor yourself.
So what engines do those above kits fit ? = M42 & M44. M43 & M40 are excluded because of Intake Manifold bolt pattern differences
What if I've got an M43/M40 engine ? = My best suggestion is to contact GKDMotorSports themselves, & they can probably do a custom solution for you!
What if i want to build my own set-up = You can, but you'll still need to fabricate the intake manifold to actually mount the compressor on it.
Alternatives ? = You can also mount a compressor NEXT to the Alternator, providing that there is space in the engine bay....
Below you'll see some pictures of common set-ups...
Where is the M43 set-up? - I haven't seen one yet, most M43 engines have turbo set-ups anyway!
How is a boost increased/reduced on a supercharger ? = The boost is adjusted by having a smaller or larger pulley basically.
So which supercharger do i need for a custom set-up ? = Eaton Roots is a popular choice, there's a few models including commonly "M45" M62" "M90" "M112"
Are there other other brands ? = Sure, I've seen BMW's set-up with superchargers from HKS, Vortech, ROTREX and such..
What BHP can I get ? = On stock-engine without any tuning, expect 140-150 from the M40/M43 engines and 190-200bhp from M44/M42 engines...
What if the engine has upgraded parts & a tuned ECU = For M40 you can probably reach 200bhp and the M42/M44 engines can probably reach 250-290bhp at extreme cases (..Like i said, 'extreme' cases!)
What does a supercharger set-up consist of ? = Usually this:
- AFPR (Auxilary Fuel Pressure Regulator)
- Custom Intake Manifold
- Eaton Roots Compressor
- Optional: Larger Injectors
- Optional: StandAlone Tuned ECU
- Idle Bypass Kit
This mod alone can provide upto 15bhp and increased Torque gains. The map/tune would normally involve:
- Fueling adjustment
- Ignition adjustment
- RPM Limiters raised
- Speed Limiters raised/removed
And for cars with Forced Induction:
- Boost Control adjusted
- Injector Map adjusted if the car has larger injectors fitted
- ECU re-adjusted for the extra air going in the car
Larger Injectors (Forced Induction):
As far as I know, most injectors for M4x engines are rated 14-19 lbs, and depending how tuned the car is, you can upgrade to larger injectors rated 30lbs-42lbs
M42/M44 = According to @m44lee, you can upgrade to 30lbs volvo injectors with adaptors from MetricMechanic (USA), as it's done on his DASC set-up.
M40 = 24lbs seems to be most common upgrade, also you can use the injectors from E30 325i (as long as it fits!)
M43 = Since the "M43" injectors are much (i mean MUCH!) shorter than the M42/44 as i've experimented with @m44lee's spare set, it is better to upgrade to larger capacity injectors of the same "physical size"....
When i say "physical" size, this is what i mean:
So like i said, the M43 injectors are different in it's physical size, however, if you find the same type EG2/BOSCH injectors, better aim for 19lbs to start with (if the ECU is not yet remapped) but you better upgrade to 30lbs once you tune/remap the car...
A major problem with these engines is that they're fitted with a "dual-mass" flywheel and this weighs TWICE than a 325 flywheel as the name would suggest.
So all this weight really does kill 1st and 2nd gear acceleration. Have you ever wondered why the car has a poor 0-60 time ? Luckily you have 3 options for that, so:
1) Upgrade to a 325i Flywheel/Clutch
2) Buy Aluminium Flywheel for the M4x engine and use the 325's clutch
3) A complete 'single-mass' flywheel kit for your engine.
So tell me about this 325 set-up ? = If you're going to upgrade to the 325 set-up, you'll need the following:
- 325 Flywheel
- 325 Clutch
- 325 Pressure Plate
- 325 Drive-pinion for the Starter Motor
- 1978 to 1983 year '323i Throw-out' bearing. <--- Yes 323i NOT 325i.
So once you have the above ^, everything should just bolt on!
So after upgrading any of the 1/2/3 options above, you'll notice the car has a much BETTER accelaration at the first few gears & deceleration will take place much quicker..
Performance CamShafts from SCHRICK (Germany):
As much as i know, there are some SCHRICK CamShaft kits for the m4x engine, most common is "264°" and "256°"
(there's probably other values but need to research on that first, as i can't read German very well!)
What is this "264" and "256" all about ? - Those numbers are the duration of the cams - basically how long the cam is open. The longer the duration basically the greater the amount of air the cams can let into the engine.
Longer duration cams will shift your power band to the right - so give you more power at the expense of torque down low. In essence you don't gain any area under the curve generally, but for racing type applications, obviously you want all of your torque at high RPMs to make more power.
Without a doubt changing the camshafts would require re-tuning to get the most out of them. Especially if the car will also be used on the Street too. This is because a re-tune with a performance camshaft will therefore prevent lumpy idle & the timing will need re-adjusting.
Also it has been stressed that when fitting new CamShafts, NEW Lifters must be used to prevent premature Cam lobe wear.
What are the gains?
You'll probably look at between 10-35bhp & including more Torque gains. The amount of BHP varies from engine-to-engine & how well the car is set-up.
The best way to actually notice these gains, is also to replace your stock exhaust with a "free flowing" system.
Cold Air Intake - Induction Kit:
Replacing the stock air box for the 'Cold Air Intake' set-up will help with engine compression as the cooler air has more oxgen on it, normally extra air will flowing through the intake system since there will be a pipe that picks up the extra air. Eg. Some CAI set-ups include catching air from the behind the kidney grills, or from the near bottom of the bumper, at the brake cooling ducts.
A disadvantage for placing it near the brake ducts is due to rain/snow, if the car continually gets soaked in water in the intake system, you'll have gasket issues!
So basically placing it where the OEM snorkel was, is much suggested.
Ofcourse CAI set-up will bring more noise to the engine, which to some people, is addictive, however, the gains for this set-up is a MAX of 5-7bhp.
Limited Slip Diff:
Since E30, Z3, E36, E46 may have different differentials from factory i won't need to add any numbers of each model. So instead, let's pretend you have these options "4.10" , "4.27" , "4.45" for the sake of comparison...
4.10 - Let's pretend this was stock from the factory for now.
4.27 - This is a good compromise of performance and everyday use
4.45 - This would be a very, very good gear for the local streets, but it will rise your RPM much higher on the MotorWays
So, Like i said, different engines , different models have different values. So it's best to find which LSD suits you.
I'll try to talk to some people with LSD's on their cars & i'll post their set-up on this thread, when i can.
Just like i said above ^ when i talked about the Schrick Cams, that performance exhaust systems are better.
Ofcourse performance exhaust systems have less restricted cats and there some which are completely 'free flowing'.
As long as your car is remapped/tuned properly, you might see an additional 5-10bhp from the custom exhaust system (However, figures vary on different cars!)
Normally, the middle silencers (middle-cats) are removed and only the back cat is replaced with a performance version, to combat bottlenecks in the car's exhaust system. As for backboxes, you would want them to sound throaty but not too loud, so therfore i've heard suggestions from these brands: "Cybox" , "Scorpion" , "BlueFlame" , "SuperSprint" and probably others... However, I haven't tried them all, so I can't tell you which one to get
NGK "IX" Spark Plugs:
Compared to the stock oem plugs, NGK IX is without a doubt a recommended performance brand, as the plugs are used in race cars. However, don't expect any big BHP values on spark plugs alone, the 'true' bhp gain with these plugs negligable, but like i said, the plugs are used in racing cars anyway.
The main advantage, for using these plugs is that: they'll charge less to spark & therefore less heat is produced. That's why some people overseas call them "Cold Plugs" , so basically less heat would mean better reliability.
Diesel M47 CRANKShaft Conversion:
I still haven't fully researched this part properly, however I learned upgrading to the M47/M47N diesel crank is another upgrade to these petrol m4x engines, as the crank has a longer stroke, therefore having a 2.1L 4-pot engine. So far, this is what is known:
- The M47 crank doesn't have the trigger wheel like the M44 crank.
- You will need to install the trigger sensor up front, using a M42 crank pulley.
- Depending on your flywheel, it "may" just bolt on directly or maybe it will require some modification (don't quote me on that since i need to research more)
- The front snout needs to be cut off and then it needs a new keyway installed for beginners.
- You need shorter rods or better pistons with the wrist pin located higher on the piston for a better rod angle on the crank.
- Long rods = good, short rods = bad due to side loading of the piston on the cylinder wall.
(Hence these rods will be aftermarker or Custom Job)
However, it's not an easy conversion as far as i'm aware! So research is the key to getting it right.
BBTB - Big Bore Throttle Bodies:
Honestly, a BBTB only makes a difference when you have all the other performance components in place. The aforementioned difference would be something like 4-5bhp at the crank, however, most known reports about BBTB are:
- Slightly Louder engine noise (Throaty sound)
- Better throttle response in 1st/2nd gear acceleration (which seems to be the most noticeable difference)
- The car would rev much quicker through the gears
"Viscous" to "Electric" fan conversion:
Basically this conversion reduces drag and inertia, so its a small gain but its essentially free, well except the cost of an electric fan switch. You'll be re-gaining some of that wasted HP since the crank has been spinning that heavy fan.
The idea is to get the electric fan to do all the work and get rid of the drag that the viscous introduces, as i've said before^.
Fitting the lower temp switch means the fan cuts in earlier so your engine temp will remain the same.
This would be very long for me to type on this thread, so instead, if you want to read more (click here instead)
But to summarise info on Underdrive Pulleys:
- It does NOT add any BHP
- The pulleys that can only be underdriven are: Water Pump & PowerSteering
- Underdriving these pulleys means the wasted energy will now be added to the wheels instead.
- Underdriving the waterpump & powersteering means less wear & tear on these units. (Lower duty Cycles)
Big Brake Kit (Front):
Upgrading the front brakes to a bigger set, means you have 3 choices:
- E46 330 = Direct fitment on any E36 Front
- E46 325 = Direct fitment on any E36 Front
- E36 M3 = You also need the M3 Hubs to fit the NON-M models.
Since you'll be having bigger brakes, it is also ideal to change your servo+master cylinder for an M3 version.
M3 Master Cylinders+Servo will fit all e36's. M3 & M3 EVO are different. So you need to ensure you have the same number of pipes as the M3 or M3 EVO
(Since some M3 versions come with an extra pipe)
Speaking of big brakes, you need AT LEAST 17" inches to clear the calipers/carriers! "15/"16 wheels will not fit over big brakes whatsoever.
Don't forget to also get:
- Braided Brake Lines. (Your OEM ones are probably old & cracking, so better to replace them regardless) (& braided lines look nice )
6 Pot Radiators:
You can improve the cooling system of the car by fitting a larger radiator from a 6_Cyl engine. (Any 6-Cyl engine will use the same larger radiator)
This is one of the easiest mods you can do do, all you need to do is:
- Remove the old radiator
- Fit the larger one (bolt on, no modifications needed)
- Bleed the cooling system properly
- Add more coolant if required
- Bleed the system again, to remove left over air bubbles
- That's it.
Oil Cooling (Forced Induction):
If the car has a turbocharger, then you know that it will share the car's oil to cool itself too & for lubrication. However, on a N/A the oil gets hot enough already, and by adding a turbo, the oil would be even much hotter! But we don't want the oil to boil up though.
The idea of oil cooling is to keep the temperature at a stable level (similar temp to cars without a turbo fitted)
Fitting an oil cooler would give you two options:
1) Fitting an E36 M3 Oil Cooler - The cooler itself mounts underneath the radiator, which means the bottom center of the bumper will REQUIRE a mesh/grill-slatts to allow air to flow through the oil cooler. But, the biggest problem is piping. You need to feed oil the FROM oil-Housing ---> to the cooler and another pipe FROM the cooler ---> to the turbo itself.
OR ELSE, you need to modify the oil-filter housing cap for an Aftermarket Cap which has 2 ports: Inlet & outlet, so basically the oil cooler will connect to those ports.
2) Other option, is the universal oil cooler for most cars, can be used on a BMW too, however, pipework is just as tricky as fitting an M3 cooler.
Luckily, I'm going to fit an oil cooler to my car soon, so i'll provide a FULL DIY guide in a separate thread
Methanol Injection (Forced Induction & Naturally Aspirated Engines) :
While Methanol Injection is nothing new, as it's been used as far back as WorldWar2 on German Fighter Planes, the benefits for a modern street car are:
- More Power: the high-octane properties of methanol, along with air cooling properties of the methanol and water, help water/methanol systems produce more power. In addition, the cooler intake temperatures allow you to run more aggressive timing and/or boost (forced induction applications) without increasing the chance of detonation.
- Reduced chance of detonation: the lower intake charge temperatures created by the methanol and water mean less chance for engine-damaging detonation.
- Economical for street Cars: water/methanol is a less expensive high-octane alternative to pure race gas for guys running high compression engines on the street.
- Built-in engine maintenance: in some cases, the atomized water effectively steam cleans the valves, valve seats, and even the piston tops and intake, reducing carbon buildup.
What power can i expect on Forced Induction car ?: With a proper set-up of the entire car, expect 20-25% additional HP. I use percentages because the actual figure varies from engine-to-engine
What about the natually aspirated cars?: 5%-10% , Again, percentages are used as BHP values actually vary from different engines.
That's it so far, as soon as i know more things that can be done, i will add them to this post. So if you know something too, please share & i'll update this thread accordingly.
Thanks for reading everyone, & i hope some of the info above ^ can be of some use to you