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From bmw-digest.v4.n271 Wed Mar 6 14:11:52 1996
From: "Burr, Barry J BB" <>
Date: Wed, 06 Mar 96 11:54:00 PST
Subject: 318i tuning; beating the ticket; cel-phones; stickers

Enough people have asked for the following information that it seems like a topic for general interest. Some of this carries over to many other BMW models.

318i-8 valve, 84-85, tuning, the (relatively) short version: Ignition:
plugs - NGK BP6ET
wires - NGK RCH?? as listed for a Honda 1200 or 1500 civic coil - Mallory Voltmaster
cap and rotor - as listed for 77-79 320i timing - 38 to 42 degrees total advance at 4000 rpm, depending on engine condition, gasoline available, how much shaved off the head, and how stretched out the timing chain is.

Valve Adjustments (absolutely fully cold): intake - six thousandths snug
exhaust - eight thousandths even

Timing Chain:
as old and stretched out as possible, with tight fresh timing gears.

torque head-bolts to 70 lbs-ft.
If head is removed for any reason, shave 15 thousandths off if you want to stay SCCA stock legal, or 60 thousandths if you want to shave as much as conservatively safe as possible. I did one motor with a stock cam at 80 thousandths with no clearance problems.

Air filter - Purolator as listed for a Chevy Sprint and Isuzu I-Mark saw off the rounded upper bulge of the air filter housing, then press fit the air filter onto the inlet ring of the air-flow-meter. Perfect fit 8-)

Air-Flow-Meter - probably no change at the springwheel, possibly one tooth leaner if your car has a lot of miles.

NEW TIP I HAVE NOT SEEN WRITTEN ABOUT ANYWHERE: BEND THE BUMP STOP BACK so the pointer can more easily reach the upper end of the carbon band. Ideal positioning is where the air flap just touches full open as the bump stop just barely makes first contact with the pointer arm.

Idle control system - REMOVED.

Also remove all idle control valve plumbing from the intake system. Plug the feeder hole in the intake boot with the rear shock absorber upper mounting nut cap that comes with Koni shocks. This is a perfect fit. A little dab of silicone sealer makes the seal absolutely airtight.

Run a breather hose from the valve cover breather fitting straight out the bottom of the car. I put a universal fit Purolator breather filter at the end of the hose to prevent sludge buildup on the bottom of my car, and needed to change it a couple of times a year.

To get a cold idle, turn up the screw a half a turn or so at the throttle butterfly. The cold idle will just barely take when its very cold, and the warm idle wil be around 1000 rpm if the engine is tuned well. I never considered a cold idle too important, as long as the engine would warm up ok.

EITHER: Metric Mechanic ported exhaust manifold, or Stahl header, but NOT THE STANDARD ONE. The standard Stahl header is a waste of money. The one you want is a custom order, made to 1-3/8 primaries, with a 2-1/4 inch outlet, including oxygen sensor fitting.

Then use 2-1/4 inch pipe, back to the free flowing muffler of your choice. Make sure this muffler has 2-1/4 inch inlet and outlets. Standard aftermarket exhausts should not be used. more noise, minimal, if any, power increase. I used a Thrush California turbo, which Jere Stahl personally reccomended. You can also use a Flowmaster or a Supertrap. Clamp a thick and strong L shaped bracket to the pipe where it passes under the rear subframe. This acts as a mount for the round rubber hanging ring that hangs down from the subframe.

If you keep the catalytic converter, Weld the 2-1/4 pipe to the outlet pipe from the cat. Get rid of the flange behind the cat. The pipe diameter at the flange's weld bead is only 1-3/4 inches or less.

Oxygen Sensor:
Mounted downstream, past the exhaust collector. Placing the single wire sensor further downstream meters cooler exhaust gas than at the manifold. This 'fakes out' the computer into running the engine a little richer than stoichiometric under load.

///Mobil 1 or Redline oil in the engine, Redline MTL in the trans, Redline Limited Slip Lube in the differential.

That's it.


Just Barry
318ti Club Sport, Hoosier Autocross R(adials) on Revolution lightweight wheels, tc kline KONIs, just counting the days until the first autocross.

If you want to go as fast as everyone else, first you have to do

what everyone else is doing.
But if you only do what everyone else is doing,

how could you go any faster????

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