Has Anyone Fitted A Turbo/Supercharger To Their NA Car?

[daveco]

I currently drive an E46 325ci '03 sport and I was looking to give it a bit more power. Thanks to the retarded motor tax bands we have here in Oirland, an M3 would set me back €1700 a year to keep on the roads (not including insurance, fuel, servicing) so that really isn't a go-er at the moment.

So it got me thinking; this engine is by far the most reliable and strongest of all the E46's I've owned, and all it needs is some extra hp to be my perfect car-it looks good, handles well, and sounds great, but just lacks that last bit of grunt.

I'd be interested to hear fellow PH's stories on any performance upgrades they've added to their own cars, and whether they did it themselves or had a specialist do the work.

[Superhoop]

Do a search on Readers rides - There are a few BMW's (A Z4M and a couple of 3 series) that have been supercharged. Definitely worth a read

[daveco]

Cheers! There's a 330 touring supercharged thread there right now so I'll read up on it.

Doogz, I forgot to mention that motor tax is set to double this December over here so an M3 would be a definite no. You lot over in the UK don't realise how lucky you have it!

[Boosted LS1]

Most engines should be able to handle a low boost set up of 5 psi which would provide a real power and torque hike whilst keeping everything else simple. Engine management and heat management would be your main issues. I'd go for a turbo set up.

[300bhp/ton]

daveco said:

I currently drive an E46 325ci '03 sport and I was looking to give it a bit more power. Thanks to the retarded motor tax bands we have here in Oirland, an M3 would set me back €1700 a year to keep on the roads (not including insurance, fuel, servicing) so that really isn't a go-er at the moment.

So it got me thinking; this engine is by far the most reliable and strongest of all the E46's I've owned, and all it needs is some extra hp to be my perfect car-it looks good, handles well, and sounds great, but just lacks that last bit of grunt.

I'd be interested to hear fellow PH's stories on any performance upgrades they've added to their own cars, and whether they did it themselves or had a specialist do the work.

I haven't, I want to and have considered it more than once and done a fair bit of research.

In general you could probably go either route, but it depends on what you want to attain, as in power delivery, cost, HP and how much fab work you want to do.

For a supercharged motor you can generally get away with higher static CR's, so they make for a good low boost bolt on to a n/a engine. Superchargers don't suffer lag either, so can make for nice road car. The downside is a supercharger is expensive to buy and fabbing up the intake and pulley system can be costly and complex.

You also have two different types of blower to choose from, PD (positive displacement), these are typically Eaton Roots or twin screw designs, they look like a log or box and often sit on top of, or up against the engine and often incorporate a specific intake manifold as part of the design and maybe a charge cooler. These offer low down grunt and make an engine feel like a much larger capacity.

Or centrifugal blowers, these look like giant turbo's and can be remotely mounted from the intake manifold more easily than most PD blowers. These are rpm dependent, so make very little boost at low engine rpms, but can make a lot more power at high rpms than a PD blower. They won't give you the "big block" V8 grunt, but are far more racey and will reward a revvy motor driven hard.


Turbo's, well the first thing is where to mount? Common front mounting on the exhaust manifold is complex and requires specific custom parts. As a rule high HP turbo motors need to run a much lower static CR than a supercharged engine, although you can normally run a light pressure turbo on most n/a engines.

Personally I'm quite a fan of the rear mount turbo's, where you locate the turbo where the rear silencer would be. There is arguably more lag, although in such a setup you don't need to run an intercooler, so total distance from turbo to intake manifold might be similar to a front mount anyhow. The main advantage here is much less custom fab work. All you need is a bracket and some pipe work.

Have a look here for some examples of this kind of setup: http://ststurbo.com/

[Captain Muppet]

I turboed my MX5 in a shed over a weekend for £500 using second hand parts. Competed in the car for two years, then carried on with track abuse for another couple of years and five years after the turbo went on I use it for half my commuter miles. Only running 6psi of boost, but the improvement in performance is dramatic.

No engine or turbo related failures in that time except for the fire. A bit of rubber pipe I'd pulled out of a skip split after three years being used as a turbo oil drain. Oopsie. Easily fixed and no damage, but next time I'll buy a new pipe.

If I was doing it again with the same budget I'd have bought an E30 3-series instead and dropped a 3.5 engine in it.

[daveco]

Fantastic info and feedback guys, very much appreciated. 300bhp/ton your info is detailed and has pointed me in the right direction! Captain M *doffs cap*

As I'm not mechanically minded, how much would this cost to fit, including the cost of the turbo/supercharger?

I'm not after serious hp, only an extra 40-50hp so do you think the clutch/manual gearbox would have to be uprated?

[Mr2Mike]

doogz said:

I'd imagine you'll spend a lot more than that, to turbocharge it properly, and keep it reliable. You'll either not be able to run much boost at all, or you'll need new pistons. All of a sudden, $1700 doesn't look like that much by the time you buy a turbo, a new exhaust, an intercooler, some management, the rest of the pipework you'll require, etc.

I agree about not underestimating the costs of a conversion, but he's looking at 1700 euro per annum rather than a one of payment. I know it's pathetic when people buy entire new cars to avoid paying £200 or so in VED, but pouring 1700 euros down the toilet every year would seriously put me off owning a car.