Basic Modification Stages

[nchiarel]

I'm in the process of finding my first 135i and reading about them...

While I know a lot about modifying a 2000 Audi S4 I know nothing about modifying the 135i. With the Audi it was:

Stage 1=Tune ECU for +70 hp ($600.00) for about 320 hp
Stage 2=Downpipes (+~10 hp) and Exhaust(+~15 hp) ($1,200-$2,500) and remap ECU for Stage 2 for about 350 hp
Stage 3=Larger Turbos/Intercoolers/other goodies (~$7,000) for 450 hp

Then you can go crazy to try for 500-550 hp

What is the common route with this vehicle? I see there are tunes, mostly seen JB3 and JB4. But the stages are a bit confusing to me. Does this mean you have to upgrade other parts such as exhaust/intake/turbos in order to get the stage 2/3 tune or is it just a choice(hey, I want 30 hp not 80!)?? What is the stock boost and what are the common tunes running boost at?

Sounds like a stupid question to me but every car is different and I just have to ask after being confused by reading too much.

Thanks guys, can't want to get the new ride...

[1speedbike]

JB3/4, Procede, and other popular tunes (Cobb Accessport, Dinan flash, Giac, etc) don't "require" any of the stage 2/3 mods that you're describing. They work a lot better and efficiently with them. For example with JB3 you can get 80 wheel HP (Terry's own claim) on a stock car. Once you add an intercooler, intake, exhaust, etc, the tune functions more efficiently and you can start seeing 120+ HP to the wheels, and probably more but I'm too lazy to check for sure right now.

For example, I started with just a JB2. Moved "up" to a JB+ with an axleback and intake at the same time. A year later, I added RAM scoops to the intake, switched the axleback with a full catback, got a front swaybar, etc. This doesn't include rims, CF bits, and cosmetic stuff.

Did I have to do it like that? No. Even with the JB+ my rear wheels spin out a lot. Instead of upgrading my intake and putting on the exhaust, I could have gotten an LSD to help with that wheelspin. Or I could have gotten coilovers for a lower/better ride. Some people, especially ones that live in hotter areas, don't like upgrading the intake at all and just get a better filter for the stock intake. With an open intake like the dual cone intakes that are readily available, you can get some heat soak and lose some power (people will argue endlessly over this). But I liked the whooshing noise of the turbos with an aftermarket intake and I'm not drag racing or anything, so that made sense for me. For what I wanna do (having fun on the streets, not really tracking the car), I went my own way, and many other people have gone their own ways.

Basically, just do what makes sense for you. Other than really obvious no-no's like upgrading springs without upgrading shocks, or something like that, you really just gotta do what you want


Also, stock boost is around 8 PSI i think. JB+ at default gives +2.75, at max give you +4.75. JB3 is obviously more, but I'm not sure how much..

[nchiarel]

Excellent, thanks for the reply. I was never much of a cosmetic modifier, but all of the performance stuff is good to know. It's crazy how each car is so different to modify depending on the weak links or parts that never need upgrading. How much power can the stock transmission handle. What about the stock engine without upgrading interior engine components?

I was just reading into the JB4... Is it risky at all to do the ECU tune? Especially the JN4 being so new? With the S4 it was known to lower the stock turbo life to around 150,000 miles so that may not be known yet.

[1speedbike]

Nobody really knows for sure about the engine life etc. A lot of 3 series drivers have been running their JB3's up and over 100,000 miles with no issues, but beyond that there's not too much that's known.

Then again, there's people with turbo and engine problems with low mileage, and one guy who took apart his engine and found massive buildup, but he was also tracking and pushing his car much more often than the average owner.

An oil catch can will also help a pretty decent amount with the engine wear issue.

I remember a while ago reading a thread about the tranny and how much power they could take as well, and there was no definitive answer to that, either. A lot of people (including Terry who makes the JB's) have been running 400+ HP/TQ easily though with the auto.

To me, the fact that we don't know for sure is a good sign, though. If we DID know how the tuning affects engine life, it would most likely be because of a lot more people with these tunes would be getting engine/tranny failures. The fact that it's not happening to almost anyone, including most of the 100,000+ miles people, is a pretty good sign..


Also, the JB4 I wouldn't call risky at all. The JB3 is probably the most popular tune on these boards, and to my knowledge nobody has had ANY issues with it, unless they were stupid and forgot to clear and error code or even left it in their car while getting serviced. If BMW finds it, they can void your warranty if something goes wrong, but the same can be said of any tune on any car. That's honestly the most you'd have to worry with a JB3/4. The JB4 builds on the JB3 and enhances it in every way, not just through raw power. Smoother and better power delivery, automatic code clearing, built in boost gauge, etc are only some of the upgrades from the JB3, so it's not really a more aggressive tune in the sense that you have to worry about it more, but it's just more well-rounded.

[Mikeshot1]

Stock boost is 8.8 psi. I added AFE dual intakes and turned the dial on the JB+ to about 2/3 so figure about 12.5 psi. Nice increase for not too much money and is safe.