Best performance upgrades

[fadeylady]

I'm new to the BMW engines, but I'm here to learn.

I'm used to working on my little '99 VW hatchback, so this inline 6 is a whole new world.

So tell me everything I need to know~

I have the '98 Z3 2.8l 6cyl, 5-speed manual (:

[jajou318]

If this is a new to you car - I'd look at bushings and the cooling system.

If you're looking for power upgrades there isn't much short of going supercharger/turbo. You can squeeze out power with n/a mods but they aren't cheap and won't net you that much.

This Z3 Manifesto used to be on this site but it is now located: https://www.sr20-forum.com/general-n...s-and-diy.html

[fadeylady]

Any specific bushings I should focus on?
I was already feeling like the bushings in the shift assembly needed replacing.

[Mr Bingley]

Best performance upgrade depends on the dollars you want to spend--for the right amount you can upgrade to a Ferrari. How much do you want to spend?

[z3forlife]

You will want to replace the rear subframe bushings with poly ones. Ireland engineering brand are commonly used here. You will probably need a new clutch slave line to improve shifting especially if it gets worse the longer you drive. Get a stainless steel line and see if that helps. You have to drop the subframe to replace the bushings so you may want to have the trailing arm bushings replaced at the same time. Some have done poly there too but they can squeak so some stick to rubber ones. It’s a 21 year old so there’s lots that could be done. Enjoy!!

[zellamay]

First, read a lot, mainly on this site. Then, as Bingley pointed out, decide what you want vs how much money you have to spend. Then, ask specific questions before doing anything. I agree with z3forlife: poly subframe bushings are the best mod for the money, but (there is always a "but") first you need to decide how much "while you're in there" work you want to do. The main performance emphasis should be to make it run as good as it can as-is. Maintenance items before mods (there could be some missing hp there). Avoid "power" options until you really know the car, most yield very small results. For example, the M50 intake is touted by some to be great, so I bought one. But after reading and driving the car for a while, decided I don't want it on the car. ...... There, that's everything you need to know. .....

[Tigershark48]

Lots of priorities

Read through the parked: threads at the beginning of this z3 sub-forum you’ll find information on everything you need to know.

[zellamay]

Lots of priorities

Read through the parked: threads at the beginning of this z3 sub-forum you’ll find information on everything you need to know.

I agree with this advice, definitely read, but with one caveat: some of those threads lean unduly in one direction. You can read one and think you have all the info and a plan, only to discover later it was incomplete. Some of them seem like they were written well a long time ago, but not updated over the years. So I would just say again, ask before spending a lot of money or time....

[ProductUser]

The cheapest and healthiest performance gains, if applicable, is to lose a few stones

[KBH22102]

Welcome and congrats on the new ride! I have a 97 2.8 so the same base driveline. My advice:

1) Make sure all basic maintenance is up to date - oil, brake fluid, coolant (and cooling system components - hoses, radiator, belts, water pump, expansion tank, etc), air filter, fuel filter, spark plugs, etc.

2) Fresh tires if the current ones are old.

3) Drive the car for a while and see how it rides. The 2.8 is a pretty powerful engine and you may already have all the hp you want or need.

4) The car responds well to suspension upgrades, so the subframe bushing recommendation is spot on. If the car has more than 50K miles then the original suspension is probably worn out and you should look into a suspension refresh. There are many options to suit your budget.

Enjoy! It is a great car and aside from the cooling system it is very durable and will give you many years and miles of smiles!

[cleanerPA]

Assuming the maintenance is up to date, the very first thing I'd do is all of the rubber bushings, even though that can be a costly job:
1. Subframe bushings (poly is preferred for durability and less movement)
2. Front lower control arm bushings (aka the "lollipop")
3. Rear trailing arm bushings
4. Swaybar bushings
5. Rear differential mount bushing
6. Engine mounts
7. Transmission mounts

I know I need to do some of these myself, as I don't think they've been done.

As for performance, you need to first make sure that the original performance is there (stage 0) by ensuring all of the maintenance is up to date and everything is working properly- plugs, coils, air filter, fuel filter, fuel pump, etc. As Kelvin mentions above, the tires are very important as well, and also the shocks.

You may find that by addressing these items, the car will feel "new" and much better to drive.

[Blacklane]

Probably your VANOS seals have not been replaced and your engine might lack torque at low-RPMs. Replacing old VANOS seals will make your 2.8 engine a lot more fun since it will give it a lot more power for take-offs.
Look over this site: http://www.beisansystems.com/

It's likely that your transmission shift pins need to be replaced. Those are the springs that make the shifter go smoothly into the next gear. If those are worn, replacing them will make shifting much more enjoyable.

You probably also need new seat bushings to keep the seats from sliding back and forth.

[Blacklane]

First, you need to spend your time and money on maintenance. It it hasn't already been done, you need to replace the cooling system. All of the plastic parts have become brittle and can fail catastrophically at any time, usually destroying the aluminum engine. You need to replace the radiator, reservoir, water pump, water pump pulley, fan, thermostat, thermostat housing, belts and hoses. (If you had a 1.9 engine, there would be two more plastic parts on the engine).

Then you need to replace the rear subframe bushings with stiffer polyurethane ones. This strengthens the rear suspension and seems to prevent the expensive differential mount tear-out. It also improves handling.

[JeffPortland]

You will want to replace the rear subframe bushings with poly ones. Ireland engineering brand are commonly used here. You will probably need a new clutch slave line to improve shifting especially if it gets worse the longer you drive. Get a stainless steel line and see if that helps. You have to drop the subframe to replace the bushings so you may want to have the trailing arm bushings replaced at the same time. Some have done poly there too but they can squeak so some stick to rubber ones. It’s a 21 year old so there’s lots that could be done. Enjoy!!

Any evidence of powerflex trailing arm bushings that are installed properly with lubricant squeaking?

[zellamay]

I've not heard of it, and my IE bushings don't squeek.

[z3forlife]

Not personally. Just random comments here on the forum.

[325bob]

The "best" performance upgrade I've had was a diff. ratio change, going to a 3.46, or 3.70 will make your car come alive for reasonable expense.,and an easy swap.