What does it take to turbocharge my 2003 BMW 525i?

dino304

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Aug 8, 2014
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Hey guys!

I am in love with my new 525i. It's 2003 BMW E39 525i, In-line 6, Automatic, 2.5 Liter, 36k miles only (new radiator, cold-air intake).
Only thing, I want a little more power, so I was thinking of turbocharging it.
Basically, here are the questions I have encountered:

1.How much does it cost to get cheap/mediocre turbo, all the parts, and labor? Again, assume some turbo size or output.

2. Will is shorten the life of my engine, transmission, or any other parts? (I'm in college so I don't have too much money laying around for a new car if I break mine)

3.How many HP will the turbo you chose to talk about add? I have around 190-200 HP right now, I believe.

4. Will I need to do any costly modifications to the engine prior to the turbo?

5.If this is a bad idea or you have time on your hands, what are some other affordable ways to increase my torque or HP?

Thanks for help in advance!
 
Solution
These are all good questions. I suggest you rean responses to these questions at "Bimmerboard" - you will get a lot of responses.

In a nutshell, turbocharging will increase the compression and result in greater HP. This also means that a higher Octane fuel will be required in order to reduce pinging. Greater stresses will be put on the cylinder head, connecting rods, crankshaft bearings, piston rings, more heat on the valves and valve seats, to mention a few things. I don't know about the effects on the cooling system, or how the trans will respond to the higher torque (and HP) produced.

Generally, engines are designed with a safety factor and modifications of this type will eat into the safety factor. Will it reduce the life of the...
These are all good questions. I suggest you rean responses to these questions at "Bimmerboard" - you will get a lot of responses.

In a nutshell, turbocharging will increase the compression and result in greater HP. This also means that a higher Octane fuel will be required in order to reduce pinging. Greater stresses will be put on the cylinder head, connecting rods, crankshaft bearings, piston rings, more heat on the valves and valve seats, to mention a few things. I don't know about the effects on the cooling system, or how the trans will respond to the higher torque (and HP) produced.

Generally, engines are designed with a safety factor and modifications of this type will eat into the safety factor. Will it reduce the life of the engine and drive train? Definitely yes!

If you haven't already done so, I suggest that you switch over to a full synthetic motor oil such as Mobil 1 10W-30 until you pass the 120K odometer reading and then change over to Mobil 1 10W-40 (this is what I did on my E39 540i) in order to provide a slightly thicker oil film to compensate for bearings wear.
 
Solution

oczdude8

Distinguished
You can get tuning chips to re-map the engine management software. However, that being said, it may not be effective for your specific model (I really don't know, you should research this).

You can also look into an exhaust upgrade, which usually gives a modest ~10hp but gives you a nice sound (if your into that stuff)

Changing the cold air intake to a quality after market one can give another ~10hp

Basic stuff such as installing high-end spark plugs and air filters can give you a couple more hp.

Turbos are not too hard to install, but they negatively effect the reliability of your car. They are finicky, even new factory designed turbo-charged engines. Eg. my 2014 turbo-charged Mercedes (stock from factory) is known to have issues with the turbo seals breaking, which causes an almost complete loss of power.

 
Dinan (Bay Area, CA) will alter the timing curves to produce an additional 12% HP for a cost of around $500. This is done by changing the software. However, the very first time the car is taken in to a BMW dealer, the software will be reset to the old software and there goes your $500 down the drain. In the event of any recall you will have to go to the BMW dealer.
 

dino304

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Aug 8, 2014
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Thank you for all your suggestions! I have already actually deleted the muffler but I will consider sparkplugs and more
 

dino304

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Aug 8, 2014
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Thank you for your help! Seems like I won't be turbocharging that car any time soon. Btw, I have already switched to synthetic
 
I got a slightly better gas mileage (about 5%) when I switched to Bosch quad electrode spark plugs from the OEM dual electrode Bosch plugs.

I used these - http://www.autopartswarehouse.com/sku/BMW/540i/Bosch/Spark_Plug/1998/BS4418.html?intcmpid=Product+Listings+Best+Seller

Please shop for good prices. I Bought from O'Reilly's.

The link is provided for illustration purposes (Platinum +4) and these plugs may not be the right ones for the 6-cylinder engine. Please check and get the right Bosch Platinum +4 for your car.

Expect rough engine running for 50 to 100 miles after changing plugs because the new plugs need to establish a new 'carbon pattern' inside the combustion chamber. This is normal.
 
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Thank you for your help! Seems like I won't be turbocharging that car any time soon. Btw, I have already switched to synthetic
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When you change oil the next time use 6 quarts of Mobil 1 10W-30 and 1 quart of Mobil 1 10W-30 Extended Performance for a total of 7 quarts that your engine requires.

The 10W-30 Extended Performance has additional friction modifiers and will help prolong engine life by reducing friction. This is the right combination. When I used just Extended Performance oil, the friction was so low that the film strength was inadequate and I got bearings noise.

If the 6 quarts + 1 quart combination works fine and it will, try 5 quarts of Mobil 1 and 2 quarts of Mobil 1 Extended Performance the next time.

Good luck!