OBD I 6cyl engine conversion resources

[Travis]

I have searched the Google machine for an engine swap procedure for the 318ti and have come up empty.

Is the OBDI procedure just so easy nobody has bothered to cover it? If I buy a wrecked 325i will I need anything else?

My buddy (Crazy Ahmed) says a '94 325 went at salvage auction for $2500 and so the (mental) wheels began to spin, imagining my (vehicular) wheels spinning faster.

Areas of concern:
A/C tubes, hoses, and condenser
Cooling package
Fuel lines, pump, pressure regulator.
Exhaust
Drive shaft
Engine ducting
Ignition
And the biggie... Wiring.

The brakes, wheels, suspension have already been cooked up with the exception of the subframe brace.

Just point me in the right direction. Please.

[Travis]

I think I am limited to '93 to '95 cars.

Where do you buy a wreck?

[J!m]

Try Bimmers South in GA.

Ph: 1-800-350-8986

Ask for Bob Alan. Tell him Jim Leach sent you.

I'm not sure they will sell a complete car, but they had the best prices when I needed parts for my conversion.

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"Speed's just a question of money. How fast you 'wanna go?"

[J!m]

A couple bits of info for you:


Areas of concern:
A/C tubes, hoses, and condenser: Use the compressor and hoses from the donor car.
Cooling package: The ti condenser and evaporator work great. The sixer hoses will bolt right up.
Fuel lines: Keep the ti lines (except the engine rubber hoses- use new ones for the engine installed. Get new clamps too)
Fuel pump: keep the ti pump(s) [it's in the tank]
pressure regulator: not sure about this on the earlier cars. Not a problem in '98
Exhaust: Good luck.
Drive shaft:Ti if you use the ti transmission. I think you will need a custom one otherwise. Perhaps the non-M 6-cylinders use the same Getrag tranny. If so, it won't matter which tranny you use.
Engine ducting: All the six-cylinder air box and ducting bolt right up.
Ignition: It's in the ECU. The coils sit right on the spark plugs.

And the biggie... Wiring: get everything from the donor car. ECU and engine harness. I THINK (not positive on this) the pre-'96 is "plug-n-play". Try www.koalamotorsport.com (http://www.koalamotorsport.com) for more info.

One thing you did not mention: Radiator. You will use the radiator from the donor car. Don't forget the lower left mount. The ti radiator is narrower than the six-cylinder radiator.



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"Speed's just a question of money. How fast you 'wanna go?"

[Travis]

Thanks for your help.

I'm guessing that the extra (40 to 50) hp from a 325 is not going to cook my transmission or clutch like an M3 mill would, so unless anyone has horror stories, I'll keep the ti xmsn and differential for the extra low-end scoot.

Any idea how the extra wieght might affect the handling? I'm worried that the car (it already understeers a little) will push like a three wheeler in the snow.

[1996 328ti]

The extra weight is not an issue.
I do several driving schools a year with my 328ti. It's still very well balanced.

You might have diff seal issues. Just watch them. The stock tranny will be fine.

If you have a 325 car, I'd grab the calipers too. Vented rotors is a good upgrade. Anything more is overkill.

[J!m]

I agree.

The aluminum 2.8 is an excellent choice for the ti. If I had realized it, I may have gone with that block and M3 or Shcrick cams. That would be the HOT set-up. I have the iron 3.2, and it does feel a bit nose heavy. However, due to the extra 100hp on tap, the weight transfer is about as easy as it gets. The heavy motor also dropped my "sport" ti another 3/4 inch or so in front, and a bit less than 3/4 in the rear. This helps controll the "plow". Now the trick is keeping the ass from spinning around...

I do have to say though, even in wet weather, where traction is non-existent with this car, it is VERY well behaved. You have to be an absolute ASS-CLOWN to spin the car around.

A friend of mine just grenaded his rear diff. He got a few good years out of it, which included spinning some MASSIVE rear tires. With the stock 16's smoking away, they make the perfect "clutch" to prevent the diff from disintegration. If larger (read: wider and/or stickier) tires are installed, the diff really needs to be replaced. I'm planning on a complete M Coupe` rear suspension. For the front, I recomend the use of the 6-cylinder's complete suspention to better carry the weight. My car is a bit soft on the corners. Koni's may solve some of this, but I think the spring rate is now a bit soft for the iron block.

I am running the ti transmission, and if you change that "lifetime fill" fluid every 25k, you should be in good shape. Change the transmission input and output seals while it's out. Mine were a bit leaky at 67k.

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"Speed's just a question of money. How fast you 'wanna go?"

[Travis]

I had not given engine selection much thought beyond the '93 to '95 325 vs. '95 M3 question. I agree that the aluminum 2.8l engine from the (MZ3 only?) would be an ideal engine. Does the 328 come with the lightweight engine, or do you have to buy one from an M roadster?
Because the wiring issue is a sticker for me, I'll have to buy some experience to pull off a 2.8l OBD II swap. Does anyone have an applicable procedure for sale or for free?

[J!m]

Yes, the Aluminum 2.8 as far as I know was Z3 2.8 only. For your swap, I would recomend also getting the wiring/ecu from a 2.8 coupe or sedan, as the "roadster" uses a few different relay locations which will complicate things for you. (as I found with my M Roadster engine)

What year is your ti? If it's a '95, then I would look for the early 2.5/2.8 wiring, even though the Z3 2.8 was after '95 (OBD-II) If your ti is OBD-II, and you want to keep it OBD-II (As I did), you will have to tow the car to the dealer after instalation for allignment of ECU and EWS, or the key won't start the car. In my case, I also had the dealer do some wiring (adding relays) due to the diferences between the roadster and coupe wiring harness', and the fact that my wiring diagrams are not as complete as the dealer's.

Don't over-complicate things by trying to make an OBD-I car OBD-II. Just get the OBD-I six wiring harness, and install it on the newer engine. The major change to the engine is the crank trigger location, but the newer engines still have the provision for the crank trigger at the front of the engine. You will have to leave the rear trigger in place, or make a custom plug for the hole.

Once the cams are changed, custom software will probably be needed to extract the maximum potential from the engine. For that application, I would contact Jim Conforti. As an option, see if you can get the wiring/ECU from a '95 M3. With the M3 cams on the 2.8 you will be pretty damn close to the 3.0 as far as performance and displacement. This will reduce your reliance on the dealer for ECU/EWS allignment.

If you go with the Aluminum motor, be absolutely certain the engine temperature does not get out of control. I believe the Aluminum 2.8 block has Nickasil bores, which cannot be over-bored. It may have iron sleeves, but I'm not sure. The sleeves can be bored to a slight degree. Not much.

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"Speed's just a question of money. How fast you 'wanna go?"