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E85 3.0i Modification Planning...

Ertyqway

Ertyqway

Member
Seattle, WA, USA
[Repost of something I put in the wrong part of the forum, which should be here...]

So...I know in my new member intro I said I was not planning to hot-rod the Z, but keep it mostly stock. I LIED.

I love the car (2006 3.0i roadster), and now that I've got the steering sorted out (run-flats are gone, new wheels, and EPS adjusted), I find that I want MOAR POWER. I mean, it's not like 215hp is inadequate or anything, but I like to drive FAST.

Reading through what other E85 owners have done with their cars, the next obvious step seems to be finding and installing a 3-stage (3.0si style) intake manifold. These seem to be relatively common from what I've seen on car-part.com, but I'm a little concerned about getting the right kind and relative condition if used. New OEM intakes are close to $1,000 US. Used (often scavenged off a wrecked X3 or 3-series) they can go for $150. Also if there are other associated parts necessary to make the swap, I don't really know what they are. I'd really appreciate advice from anyone else who's done this and can describe the process/experience. Also, whether or not it makes any difference to put in a cold-air induction box with it. I've heard mixed things about that (to the extent that the stock filter box is actually very good if it's got a clean high-flow filter in it).

After that, I'm thinking I should re-do the exhaust: headers, free-flow cat, etc.

And then ... SUPERCHARGER! How could I resist that? My wife may take some convincing, however.

The intake and headers probably get the car to around 275 hp from its current 215. A supercharger (VF Engineering - 6 to 8 pounds of boost) probably takes it up into the low 400s somewhere. At that point, I assume I'll need to have a serious conversation about brakes and drivetrain. Stock brakes and rear end are likely good to the high 200s. But high 300s to low 400s is a different animal altogether.

Of course, the ECU is going to need some TLC with all this as well.

My goal is to have something still very drivable as a street and touring car, but with a big reservoir of ooomph for when I want to launch into the next time zone. And maybe the ability to humble an M3 or few.

Thoughts? Recommendations? Cautionary tales?
 
Tuning a nearly 20 year old car of unstated mileage is never a good thing. Apart from a free flowing filter and decent oil and spark plugs I would be content with how it performs . Unless you really want to leave everything else at traffic lights with a few strategically placed m stickers .
 
This is not my first rodeo when it comes to tuning old cars, though this might actually be the newest one I've ever worked on. There's also a very active tuning community here locally, though none of them have gotten into working on Z4s yet as far as I can tell (do A90 gen V Supras count? They are basically just Z4s with different body work lol). The BMW tuners are all building out 3 series for racing, which is not my thing. My car only has 48,000 miles on it and checked out with a clean bill of health with the mechanic after I bought it, so it's a pretty good base for building something out. It was also not an expensive car, so I don't feel it's too precious to modify.
 
Here's an 8-year-old thread from Bimmerfest about somebody doing the intake swap: https://www.bimmerfest.com/threads/3-stage-intake-manifold-1st-impressions.1130233/

This is the first modification I'm thinking about doing: 3-stage (si) intake + cold air box + ECU tune. Seems to add about 40-50 hp on the dyno for those who have done it...about what you'd expect from basically turning the car into a 3.0si. I was wondering if anyone here had done anything like this, or what other Z4 modifications folks here think are worth doing.
 
I've done that on my old 125i - its the same engine as the 3.0si (with the 3-stage manifold) but detuned, so easy tune and I added a larger aFe airbox intake. Don't like the cone filter intake as it sits in the engine bay soaking up heat and does bugger all. So for you, get the manifold, get a tune, this will cost you $300-500 for a solid 40bhp gain and torque and enjoy. Rest I wouldn't advise, if you like driving. Of course if you prefer tinkering more than driving then sure but there are better cars for doing that imo
 
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