Indecisive between supercharging and turbo charging

[BillyBob]

Oh, and there's a world of difference between 8 and 15 psi... Even more so when you take into account turbocharger sizing, or what kind of supercharger kit you'd like to use, where you're building the motor to rev to, etc.

Rather start off with these two questions:

How much power do I want?
What's my budget?

Whether going turbo or supercharged, you're somewhat limited by what the stock motor can handle - M54B30 reliability starts becoming iffy around 0.6 bar or thereabouts on stock internals - which should see you pushing in the region of 240-250 kW on a supercharged setup, and around 270-280 kW on a well-matched turbo setup. (flywheel figures)

Bear in mind, the M54B30 doesn't like revving - stock cams peak early and drop off dramatically, the head doesn't flow too well for big power applications, and there's a well-documented issue with continuous high revs backing out the oil pump nut with catastrophic results - so if you're thinking you're going to build a reliable 1-bar boosted 350 kW 7500 RPM animal on a stock motor, then you've got the wrong platform as a starting point..

To get to 350 (Supercharged) - 400 kW (turbocharged) reliably, you will need:
A built bottom-end with forged rods and pistons.
An aftermarket oil pump - or at least for the nut on the OE pump to be replaced and the shaft-welded in palce
Aftermarket FI cams - Schrick has a nice 264/248° set if I'm not mistaken.
Headwork (exhaust ports are too restrictive from factory)
Uprated clutch

Bolt-on forced induction on the M54 will yield you the same or sliiiightly more power than an E46 M3 (250-280 kW)... then the M3 still has better brakes, better suspension and a limited slip diff. However, your car WILL be fun and entertaining, and will run away from an E46 M3 at altitude in a straight line. If that is all you want, go for it... but bear in mind that the spend to get it there will cost you nearly what just buying an E46 M3 would cost you.

If you want reasonably good power (350-400 kW), you're going to spend R120k+ rebuilding the motor and doing the conversion properly - and you'll never see that money back when time comes to sell the car. That same power can be had from an E46 M3 with a simple bolt-on Supercharger kit.

So, yes - there's merit to going the FI route on a 330i - but only really if you're going for a bolt-on kit. For big power applications, there are much better avenues.

In short:

Unless you specifically NEED 4 doors or you have a huge sentimental attachment to the 330i with the intention of driving it till the wheels fall off, you're better off just upgrading to an M3 for your thrills.

 

[Coisman]

Hmm.

okay here is another option>


Charge the 330i, or just buy an M3? And maybe charge that in the next 12 monhts :fencelook:

BIGGEST issue with this plan is to find an M# that is still in a good condition, and trust me when I say this is not easy!!
I litterally test 20-30 cars a week for forum members, and the times I do test M3's 99,99% of them are crap!!

So yea, in the end of the day, your money, your choice!! :thumbs:

 

[Crash_Nemesis]

VF engineering gets 570hp out of the e46 M3 with their stage 3 supercharger kit. Running 8psi. No forged internals, no built engine. Stock compression. Just bolt on supercharger kit. Do you need more than 570hp? Then if you do, turbo is the way you want to go.

Turbo charging will require you building the engine. Remember, you need to lower compression on Turbo Builds. YOU DO NOT have to lower compression with a supercharger build. Turbo charger builds often require stronger pistons to deal with the massive force of pressure they suddenly throw into the engine. Turbo's can spool up to 15000rpm or higher, creating massive pressure. Superchargers will only rev up as high as your engine. In your 330i's case, 6500rpm. But the power will be smooth and linear. Turbo will be nothing at first due to the lag, then suddenly a massive jolt as the power comes in. Its all up to your taste.

Robot to Robot and rolling runs, Supercharger will beat Turbo every time due to the lag and traction problems Turbo cars have. But in a quarter mile and long sprints, the turbo car, if it has more power, will eventually catch and pass...

As a few have mentioned. It depends on your use for the car. Are you drag racing? If so, TURBO THAT BAD BOY.

If you track racing, SUPERCHARGE.

It all depends how you want the power delivery. In the end, they both very effective ways of getting a car to its full potential.

 

[P1000]

VF engineering gets 570hp out of the e46 M3 with their stage 3 supercharger kit. Running 8psi. No forged internals, no built engine. Stock compression. Just bolt on supercharger kit.

S54 stock = forged. (albeit high-compression, which is really the problem)

The advantage with stock is, swirl will always be better than any aftermarket hack.

 

[moranor@axis]

*35 uses Vanos ect to build boost quickly and smoothly... not going to happen with aftermarket turbo unless you fiddle for years to get it 100%

have a look at ESS they have bolt on 7-8psi kits as well as internals for 15psi super charger is much easier to get smooth and consistent and if you not going to boost over 15psi will deliver the power...

 

[monster]

.........Turbo charging will require you building the engine. Remember, you need to lower compression on Turbo Builds. YOU DO NOT have to lower compression with a supercharger build.......

Please explain.
As Far as i understand these things, they both do exactly the same thing but in different ways.
8psi is 8psi wheather it is from a tc or sc.
So why then only drop compresion on tc aplications?

 

[BillyBob]

.........Turbo charging will require you building the engine. Remember, you need to lower compression on Turbo Builds. YOU DO NOT have to lower compression with a supercharger build.......

Please explain.
As Far as i understand these things, they both do exactly the same thing but in different ways.
8psi is 8psi wheather it is from a tc or sc.
So why then only drop compresion on tc aplications?

What Crash saying is partly true in certain applications, but not a hard-and-fast rule...

Dependent on the size of the turbo, the wastegate and associated tuning, you could have a sizeable torque surge (and boost spike) when the turbo spools up, which could break stock internals... if boost levels are kept moderate and boost is ramped up gradually through a well-mapped wastegate duty cycle, a forged rebuild isn't a must-have on a turbo conversion.

Hence my mention of a well-specced turbo for the application.

Superchargers on the other hand have a linear boost curve, which doesn't have an unnatural spool-related torque spike, and is thus generally considered to be easier-going on the engine.

Dropping compression is the generally employed way to squeeze a bit more boost from a forced-induction application, as it lowers the knock threshold a bit and also sees a turbo spool up a bit more gradually.. Unfortunately, it has the trade-off of reducing engine responsiveness off-boost.

 

[Burgy]

What sort of power do you want to make?

 

[Crash_Nemesis]

Exactly what BillyBob just said.

:thumbs:

 

[monster]

I get what you are saying.
Comp ration is lowered to help with detonation and more boost.
Internals are beefd up for massive boost/power.
What i am trying to say is thst comp ratio and internals arent nesacaraly the same
I just dont buy the "dont have to" for the sc and the "must" for tc.

If you boost both aplications at the same amount they should both need the same modification.

 

[moranor@axis]

much easier to regulate SC boost so you can avoid detonation easier with timing changes ect...

anything can be done but for low to mid boost range SC is easier... at High boost the SC runs into problems...

 

[osiris]

Me personally, I would go the turbo charger route!

As people have already said, later on you will want more power and a turbo will offer you that to you.

a Super charger kit will set you back like 80 grand which is bloody expensive for a bolt on kit if you ask me! I would much rather spend a little more and get a turbo conversion done properly!

Sav speed quoted me 75k for a turbo conversion on my old 325i and that was for MASSIVE power and he offers a guarantee etc etc, I have seen a few of his cars that have been turbo charged and they are strong! Race after race after race after race and the car just keeps going. pulling super bikes and all sorts without ever failing!