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      06-28-2009, 10:51 AM   #1
synclastica_86
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New to tuning... many questions:

When car tuning is concerned, I a noob in every sense of the word. I have never done any modification to my cars before but would like to get started. I am quite mechanical inclined and do understand how many of the parts work. Nevertheless, I have many questions, both technical and practical that I want answered (my question are general questions and not BMW specific). Thanx for the help guys!

Technical:
  1. ECU: How would the modified program cope with the other parts of the car? Modern cars have a lot of different computer systems, will changing the ECU affect them? Will things like the launch control still work properly?
  2. Engine: There are lots of ways to squeeze more power from the engine. Will the ECU know how to control the new parts or do I have to modify the ECU programming with it? I'm sure companies that produces superchargers and turbos will make sure that the engine can take the extra load, but what about further down the drive train? Can a gearbox designed to take the 400 odd hp handle the 500 after a supercharger? How much margin was engineered into the drive train at the factory, and how much could it take?
  3. Gearbox: If force induction was used, I'd think that the torque/hp curves will be different. How will the gearbox cope with that? For gearboxes that have an automated program such as the DCT, will it still operate properly and figure out the new shift points? Will it still blip (rev match) the right amount? Even worse, will the gear ratios still be suitable? Also, I rarely see any after market gearboxes, do they exist?
  4. Brakes/ suspension: This part is what I'm most comfortable with. Bud how would they work with the other mods. The weight of the cars will change as mods are added and when weight saving measures are taken. Will the suspension system be able to cope with those changes or do they have to be retuned after every mod?
  5. Aero: Are they just for looks or do they actually give down force? This is actually the part that I fear the most. Big auto companies are resource plentiful and have access to wind tunnels and expensive simulating programs to help them figure out the proper aerodynamics, but how can small after market companies do the same with relatively limited resources? People sometimes only go for parts of a kit or put different kits together, will this upset the balance of the car? I can foresee a car plowing into corners if some one installs a rear wind and does not adequately condensate up front. With out wind tunnel testing, how can I set my aeros up?

Practical:
  1. Warranty: Will my car still be covered after mods? If not, will the warranty be voided on only the part of the car affected my the mod or the entire car?
  2. Insurance: Will mods affect my coverage? Do I have to report to the insurance company every time a mod is installed? Do I even need to report at all? If a claim occurs that results from the malfunctioning of a mod, will I be at fault?
  3. Stock parts: Will I get the stock parts back after a mod? Should I keep my old part or get rid of it? Where can I sell my stock and get a good price for it?
  4. Shopping/ installing: Should I get the mods through the installer or will I be better off ordering the parts myself?

I know that there are a lot of questions here, but thanx for helping out!
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      06-28-2009, 04:20 PM   #2
e36jakeo
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Quote:
Originally Posted by synclastica_86 View Post
When car tuning is concerned, I a noob in every sense of the word. I have never done any modification to my cars before but would like to get started. I am quite mechanical inclined and do understand how many of the parts work. Nevertheless, I have many questions, both technical and practical that I want answered (my question are general questions and not BMW specific). Thanx for the help guys!

Technical:
  1. ECU: How would the modified program cope with the other parts of the car? Modern cars have a lot of different computer systems, will changing the ECU affect them? Will things like the launch control still work properly?
  2. Engine: There are lots of ways to squeeze more power from the engine. Will the ECU know how to control the new parts or do I have to modify the ECU programming with it? I'm sure companies that produces superchargers and turbos will make sure that the engine can take the extra load, but what about further down the drive train? Can a gearbox designed to take the 400 odd hp handle the 500 after a supercharger? How much margin was engineered into the drive train at the factory, and how much could it take?
  3. Gearbox: If force induction was used, I'd think that the torque/hp curves will be different. How will the gearbox cope with that? For gearboxes that have an automated program such as the DCT, will it still operate properly and figure out the new shift points? Will it still blip (rev match) the right amount? Even worse, will the gear ratios still be suitable? Also, I rarely see any after market gearboxes, do they exist?
  4. Brakes/ suspension: This part is what I'm most comfortable with. Bud how would they work with the other mods. The weight of the cars will change as mods are added and when weight saving measures are taken. Will the suspension system be able to cope with those changes or do they have to be retuned after every mod?
  5. Aero: Are they just for looks or do they actually give down force? This is actually the part that I fear the most. Big auto companies are resource plentiful and have access to wind tunnels and expensive simulating programs to help them figure out the proper aerodynamics, but how can small after market companies do the same with relatively limited resources? People sometimes only go for parts of a kit or put different kits together, will this upset the balance of the car? I can foresee a car plowing into corners if some one installs a rear wind and does not adequately condensate up front. With out wind tunnel testing, how can I set my aeros up?

Practical:
  1. Warranty: Will my car still be covered after mods? If not, will the warranty be voided on only the part of the car affected my the mod or the entire car?
  2. Insurance: Will mods affect my coverage? Do I have to report to the insurance company every time a mod is installed? Do I even need to report at all? If a claim occurs that results from the malfunctioning of a mod, will I be at fault?
  3. Stock parts: Will I get the stock parts back after a mod? Should I keep my old part or get rid of it? Where can I sell my stock and get a good price for it?
  4. Shopping/ installing: Should I get the mods through the installer or will I be better off ordering the parts myself?

I know that there are a lot of questions here, but thanx for helping out!
The answer to most of your questions is "it depends."

ECU tuning runs the risk of voiding your engine warranty IF BMW can detect it. Raising your rev limiter is an easy way for them to detect it. Other paramters minus rev limit change are trickier to detect and/or prove.

More power does stress driveline parts more. A bit more (say <50 HP and/or torque) is probably negligible in terms of limiting durability. Above that you may limit overall durability, but it will take many tens of thousands of miles to figure out what part is the limiting factor (when it breaks).

Breathing mods (intake, exhaust) combined with an ECU tune to take advantage of the improved breathing are common beginning points. However, with a highly tuned stock engine like the S65 HP improvements will be somewhat limited (Pencilgeek achieved ~40 hp, I believe, which is excellent for an NA engine). Superchargers can add huge power and torque but add weight, cost, compexity, and a lot of stress to the engine. Don't expect an SC engine to last near as long as a non-SC car, but 600 HP+ rarely comes cheaply!

Two "stroker" kits exist for the S65 that bring it to 4.6 Liters and ~520 HP. The price is steep ~($30K installed) but the characteristics of the NA engine are preserved, presumably durability will be less of a factor than an SC engine, and one comes with a 4/50 warranty. Before turing your M3 into a $105K machine with a stroker kit and suspension you may want to test drive a Porsche GT3 . . .

The stock suspension is very good, even as the track. There are many systems coming on line if you want even better suspension for racing applications. They won't improve street handling much. Turner Motorsport is taking pre-orders for the Bilstein PSS10s, which are adjustible. Look at the suspension separately from everything else. if you go with an SC suspension is kind of a must to keep the car from squatting too much under acceleration.

I would not expect aftermarket parts to create aero downforce. I'd say the car is damn stable at speed bone stock. For aero, refer again to GT3.

I personally did not tell my insurance company about my mods, but that is up to you (+/- either way).

If you know how to work on a car you can do the work yourself. To keep a Dinan warranty I believe you have to have the dealer do the work.

If you plan on keeping the car for a long time maybe just sell the stock parts. If you might want to switch back soon then keep them.

Good luck with the mods!
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      06-28-2009, 07:19 PM   #3
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Technical

1. Changing ECU mappings in terms of timing, fuel, valve timing, rev limiter, speed limiter won't affect other systems such as launch control and DCT

2. S65 runs a MAP-based (manifold absolute pressure) system to calculate air mass, which doesn't accommodate changes to volumetric efficiency quite as well as MAF (mass air flow based) systems. Still it's a fairly given principle that if you increase VE you will increase power. It's always best though to tune your car for your modifications, to maximise your investment and primarily to make sure the car will run reliably.

3. I don't think manual gearbox will be an issue, unless you are looking at serious torque (say 700NM+). IIRC the DCT gearbox is rated to cope with up to 600NM torque, so it should accommodate even mild FI setups. If you change final drive ratio, DCT still operates correctly, although I've heard some anecdotal evidence that you may notice slight variations in behaviour.

5. Aero parts can have a major impact on handling and performance. Most good aero suppliers are working from the stock configuration and adding a specific component or set of components to achieve a certain outcome (e.g. better track handling). So stick with one aero supplier if possible. And you generally give up something to gain something with aerodynamic mods (e.g. increased drag vs increased handling). From what I've seen, most aero parts for the M3 are purely cosmetic.
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