BMW e30 engine mods

E30 ENGINE M ODIFICATIONS ODIFICATIONS

Bolt-on Modifications Modifications If the stock engine in your E30 doesn’t have quite as much power as you like, there are a few things you can do without tearing completely into it. Don’t expect miracles from external modifications, but they can make your car much more fun to drive without taking too much from its reliability and comfort. M10 Sadly, even the cheapest, smallest cars on the market today have more power, but an M10 is enough for a daily-driven E30 to keep up with modern traffic. It’s possible to squeeze a few more horsepower out of an M10 engine, but in general it’s best to appreciate it for what it is—a reliable, tough little engine that gets decent fuel economy without giving up useful performance. A four-into-one header can add a few horsepower but they are becoming hard to find and have some

1

drawbacks for a street driven car. In general, headers add significantly to underhood heat and have a tendency to crack and rust out quickly. It is possible to swap in a larger airflow meter for the Bosch L-Jetronic system, using the original circuit board, but unfortunately the original analog EFI system is not tuneable in the same way that a digital one is. M20 The M20, like the M10, is fairly well tuned from the factory. There is not a lot of hidden horsepower just waiting for you to tease out. There are a few things that can be done to make the engine run better and make a little more power, on the order of 5 to 10 percent at the wheels. A good-running, stock M20B25 can put out up to 145 or so hp at the rear wheels, depending on many factors. If you are serious about getting more power out of it than that, you should pay for a dyno run on your stock car so that you

have a good baseline. Then you can determine whether the modifications you make are actually helping performance. Dollar for dollar, the best thing you can do with a good-running M20 engine is get a good chip for the stock ECU. It’s not hard to learn how to modify it yourself if you are electronically inclined. Get yourself a spare ECU, an EPROM emulator (I like the Moates Ostrich), and have fun. The next step is to reduce the intake restriction by replacing the airbox with a cone filter and heat shield for a small increase in airflow and power. For even more gains you can swap out the air/fuel meter (AFM) for a larger one from a 535 or 735 with the 3.5-liter engine. You may have to swap circuit boards from your AFM to get the idle to smooth out. If you have access to your engine tuning, through an aftermarket supplier or a DIY setup, the best thing you can do is convert your AFM to a mass airflow (MAF) sensor. Sev-

Get The Full Book Here: www.CarTechbooks.com/e30

eral companies offer this service and the factory AFM is one of the biggest impediments to good M20B25 power. Once the intake side is taken care of, there are some small gains that can come from larger injectors if you are running out of fuel with the stockers. Beyond that a header and free-flowing exhaust can help incrementally. A very good running engine can see more than 155 hp at the wheels with these modifications. Unfortunately that’s about it for external modifications. You can swap the cam and have the intake ported, but again you won’t see huge gains. The stock valve-to-piston clearance on the M20 engine is very tight; there is not much room to increase the cam lift without hitting a piston. S14

The S14 is one of the most highly tuned BMW engines ever produced and bolt-on modifications are unlikely to add much power. There are a few horsepower hidden in the exhaust system, especially if you

have a plugged catalytic converter or damaged tail pipe. The BMW Motorsports Evo airbox, with its cold-air intake, is a good addition to an otherwise stock engine. This replaces the airbox with parts that were created by BMW for later, higher-powered versions of the E30 M3. It draws air from under the front bumper, for lower intake temperatures. This gives a decent power boost over stock, with no downside. The stock air filter is retained and can be replaced with a free-flowing aftermarket K&N element if desired. Once these modifications are done, a custom or off-the-shelf ECU chip can unlock more potential in the engine package. An S14 engine, carefully tuned with these parts, should be good for more than 160 hp at the rear wheels, assuming it is in good condition with high compression numbers and minimal wear. M42 The first step in tuning an M42 is with a chip or ECU tweaking. The stock fuel and ignition curves are

pretty conservative and it’s easy to gain a few horsepower with a bit of tuning. Of course with such a high compression ratio any chip requires you to use only the best gas, at least 91-octane. In some cases an octane booster is needed to avoid detonation. The cam sprockets on the M42 are both adjustable and there is a bit of horsepower that can be unlocked by tweaking them slightly. Many people have had success with 5 degrees advance on the intake side and straight up on the exhaust side. This adds a bit of torque without affecting high-end power. A cold-air intake (with an effective heat shield), just like those advised for the 325i, also helps with high-RPM breathing, although the power gains may be minimal. You can add a cat-back exhaust for better sound and weight removal, but don’t expect drastic power increases from one. Beyond that, the M42 has the unloved dual-mass flywheel just as the 325e’s 2.7-liter engine does. Replace the 28-pound behemoth with either an aluminum aftermarket flywheel or a 325i flywheel (preferably lightened). Use of the 325i flywheel requires the use of a matching 325i starter pinion and the longer throw-out bearing used for Getrag 260 conversions. The E30 with an M42 is a great, well-balanced car with decent performance and excellent handling.

The factory air cleaner and AFM are far more restrictive than anything shipped on a modern car. Replacing the box with a cone filter improves real-world performance.


2

However, it is perhaps not the best combination for modification, since the engine is so limited in its capacity for more power. The compression ratio is too high for a turbo conversion and the engine is in a very high state of tune already (for a 1.8-liter engine).

Internal Modifications If you’re at the point in modifying your car that you’re ready to tear into the engine itself, you’ve probably gotten here by blowing

something up. If you haven’t blown something up yet, you’re probably looking at a block with a few hundred thousand miles on it. Maybe it smokes a little, maybe it rattles a little, or maybe it’s hard to start in the morning. Some people might consider a proactive engine rebuild, but there aren’t many people willing to spend the kind of money that it takes to build a tough short block without it being absolutely necessary. However you came to consider building a new engine, the planning process is still the most important

part of the build. Before you turn a wrench, and even before you whip out your credit card, you should know exactly what your power goals are and what parts you need to achieve a reliable short block at that power goal. This section will help you make some basic decisions about compression, bore, stroke and engine type. Also talk to local engine builders, if you’re lucky enough to have a BMW expert nearby. They’ll have definite opinions on what parts you should be using. Don’t set yourself up for a

Equal-length headers (if they are legal where you live) are a great way to squeeze some more power out of the M20. However, they do not have much effect compared to the excellent stock exhaust manifolds. (Photo Courtesy Ireland Engineering)

Headers are most advantageous at high RPM; their biggest disadvantage is poor cold-weather driveability and cracking. If you are building a track car they are a good choice, but the street manifolds are better in most cases. (Photo Courtesy Ireland Engineering)

3


broken engine a few months from now. Rather, build something that you know will be able to handle your power and usage demands. It might be better to save up a little longer to get those rods and pistons you really want instead of rushing a build that does not achieve your ultimate power goals. Ask suppliers about the weight of their rods, pistons, and connecting rods; the lighter the better, since a

light rotating assembly (crank, rods, pistons, and flywheel) is like free acceleration. Because the reduced weight is driven through the transmission to the wheels, it’s multiplied in effectiveness. Assuming suitable gearing, this means better acceleration. When you get the parts home, have them balanced, too, for a smoother-running mill. At the same time, if you’re building a street car, try to keep your

build moderate. As cool as it sounds to have a full-race engine under the hood of your daily driver, it’s not cool at all to drive. Street cars should generally be able to be driven anywhere without worrying about pinging, poor cold-weather performance, and hard starting. Race cars are much more forgiving; nobody cares if your race engine has no real power under 3,000 rpm. Race engines are set up com-

If everything else externally has been done it’s possible that a ported intake manifold with a larger throttle body will help slightly, but don’t be surprised if you never see 160 hp on the dyno readout of an otherwise stock M20B25.

The muffler on this exhaust is much lighter than the factory exhaust. That’s reason enough to go with a custom exhaust. (Photo Courtesy Ireland Engineering)

A free-flowing exhaust such as this custom piece helps quite a bit. It also makes your M42 sound better. (Photo Courtesy Ireland Engineering)


4

pletely differently than street engines. They have looser bearing and piston clearances, higher compression, lighter and more expensive materials, etc. High compression is much harder to tune around and live with, especially in 91-octane states such as California. This means (obviously) that you need to buy different parts and order different machine work for each type of engine. It does not pay to be a bench racer; at first you’ll be jazzed at the extra power of your high-strung engine, but after living with high compression and poor low-speed performance for a couple of months, I can almost guarantee you’ll regret being overly aggressive. (Autocross doesn’t usually count as race use, in case you’re wondering.) For a good street engine that won’t be turbocharged, don’t go above 10.5:1 in compression ratio. In the long run you may find that you are happier with a 9.5 or 10.0:1 ratio. M10 Of course most M10 engines are getting pretty high in mileage by now and it doesn’t make sense to modify a worn-out engine. If yours smokes, rattles, or uses oil, don’t try to get more power out of it—the higher revs will kill it in no time. If smog laws or emotional attachment rules out an engine swap, I suggest you rebuild it, applying proven hotrod tricks at the same time. You will end up with an engine that makes more power and uses less fuel than any stock 318. Even later 318is models with the M42 won’t have as much torque as a well-built and intelligently modified M10. If you are going to start from scratch, have the head lightly ported,

5

These are pretty typical rod bearings with more than 150,000 miles on them. They are not worn out per se, but they don’t have much life left in them. (Photo Courtesy Ireland Engineering)

install new valves, guides, springs, and a performance camshaft. In the bottom end, find a crankshaft from a 2.0-liter E12 320i or a 2002. If you can find one, an M3 crankshaft can be used with some minor machine work. Use your stock rods with a set of E12 2.0-liter pistons. The result is a 2.0-liter engine (2.3 liters with the M3 crank) that looks stock, passes emissions testing (if you have it in your area), and produces up to 130 to 140 hp. Your car will be as fast as any stock E30 except the M3 and the cost will be very little more than the cost of a standard rebuild. For anything more than this you are probably better off swapping to a newer engine design or another car. Read “Supercharging and Turbocharging” (page 94) if you want to keep your engine for nostalgic or other reasons—a turbo is a great companion to a stock M10 engine, although in my experience your hunger for power soon overcomes the capabilities of the engine’s bottom end. M20 The M20 can be built into a powerful, flexible engine that is perfect for the street or track. Most people

don’t bother to build an M20, preferring instead to swap to a later M50 or S50 engine, but there is a lot to recommend for a performance build. For one thing, a stock-looking M20 engine, even one with a massive stroker kit and mild cam, can pass visual smog checks in states that have such requirements. Engine swaps can’t always be made smog legal. Second, engine swaps involve complicated wiring, shift linkage, and transmission mounting issues. I talk more about them in the section “Engine Swap” (page 105), but not everyone has the time, money,

These bearings are worn out. You wouldn’t want to trust them in your daily driver. By 150,000 to 200,000 miles all your rod bearings probably look like this and could probably stand to be changed. (Photo Courtesy Ireland Engineering)


or knowledge needed to install a new engine and troubleshoot the inevitable issues that come up. You can build an M20 that produces 200 hp at the wheels without using many exotic parts. This is enough power for just about any E30, especially one that still looks stock and drives like a factory car. It might cost a little more than a barebones engine swap, but the result is more true to the character of the E30, if that matters to you. The 325i head, intake, and engine management system are

the best place to start on an M20 build. If you are starting with an eta engine, keep the great long-stroke crankshaft for a street engine, but use a 325i top end. If you can make them work, factory 325i pistons are an excellent choice for an engine that won’t be turbocharged or raced. They are good-quality Mahle cast units that are much lighter and cheaper than any aftermarket forged ones. M20 Stroker If you are building an M20 engine

from scratch, your options for engine capacity are wide open. The 325i crank stroke is only 75 mm, but the eta crank is 81 mm. The extra capacity is more than welcome for a street car and the cast eta crank has proven to be plenty strong enough for high-RPM use. Other options include the M50 and S50 crankshafts from later E36 cars. The 84-mm stroke crank from the 2.8-liter M3 engine or the 89.5mm stroke from the 3.0l S50 engine can both be used with a bit of machine work. Much talk has been made of bolt-

Everything else in your engine wears as the years—and miles—add up. This oil pump gear has many thousands of miles and the wear to prove it. The pitting along the front of each tooth is from wear and dirt in the oil.

It almost never hurts to “over-build” a short block, especially one destined for turbo use. The desire for power can become very addictive—many of us have set out to build “just a 200 hp” engine and find ourselves wishing for more power a few months later. (Photo Courtesy Ireland Engineering)

The M20 oil filter adapter has a tendency to get filled with gunk from infrequent oil changes and to leak from the seal between the adapter and the block. Both can be fixed without an engine overhaul but are better done as part of one.


6

ing an M20B25 head onto an eta or “super” eta block to build a low-buck stroker. This can be done; however, there are a few issues. First is the compression ratio. The eta piston has a flat top, while the i piston is domed. To compensate, the i head has a large combustion chamber and the eta head has a small one. If you bolt an i head directly onto an eta rotating assembly, the compression ratio is quite low, around 8.5:1, or perhaps a little lower depending on how your tolerances add up. Unfortunately it’s not as easy to fix as just bolting M20B25 pistons and rods onto the eta crank. The eta rods are 130 mm long and the i rods are 135 mm long. With the i pistons and rods, the valves and pistons are far too close together; in fact, they may touch. Using i pistons with eta rods is possible; however, the block must be milled around 2 mm to make up for the difference in piston compression

heights (from the center of the pin to the top edge of the piston). The ideal solution, although expensive, is a set of custom pistons that lets you use the eta crank (or an M50/S50 crank) with the i rods and head. Since the i rods are longer, they make a better-revving engine. The i rods can be replaced with M50 rods from an E36 M3, which are lighter and stronger. These are a good alternative to expensive aftermarket rods. To make use of the i head requires that you use the entire 325i Motronic M1.3 fuel-injection system, including the harness, all sensors, intake manifold, pulleys, thermostat housing, AFM, injectors, and fuel rail. You must use the 325i ECU as well and swap to a 325i or 318is tachometer to show the revs beyond 5,700. The stock M20B25 valve sizes should be sufficient for just about any combination of internal parts because the valves are quite large for an engine of this size.

An M20 stroker with the abovementioned parts, an efficient exhaust and intake system, and careful tuning can easily make 200 hp at the rear wheels. This is more or less the limit of M20 tuning without going to a turbocharger and makes an excellent street car. For reference this is more power and torque than a stock E36 M3, and with a much better powerto-weight ratio. S14

In Europe BMW produced a 2.5liter version of the S14 and the crankshaft is easily available in the United States from several BMW parts suppliers. The Sport Evo crankshaft gives an 87-mm stroke; combined with a set of BMW 95.5-mm-bore pistons the resulting engine is 2.5 liters in capacity. Longer-stroke crankshafts are available from the aftermarket but this is a very expensive endeavor, since custom pistons and/or rods are required.

The gunk at the bottom of this oil pan is a result of infrequent oil changes (left). To avoid this make sure you change the oil often. To solve it, rebuild the engine and check out the oil system thoroughly. This is the same pan after a bath in the parts cleaner (right). Make sure that you find a machinist with a hot tank to remove all the gunk from internal engine parts. (Photos Courtesy Ireland Engineering)

7


The S14 head is a magnificent piece of engineering and there is very little to improve upon. The intake and exhaust ports can benefit from a touch of porting (particularly in the bowl area) and a decent multi-angle valve job. The cams are very good for a street engine, although for race use

a slightly longer duration intake cam can be used. An S14 with an aftermarket ECU, a stock set of cams, and a 2.5-liter bottom end fixes all of the power complaints that many have with the E30 M3. It gives the car a massive boost of mid-range torque that improves its feel on the street without hurting performance in any other arena. M42 The 1.8-liter M42 is a great engine—similar in architechture to the S14 but with a real-world design,

One of the weak internal parts of the M20 engine are the rockers/cam followers. They tend to crack and split, even in stock engines. The improved parts developed by Ireland Engineering have added material to combat this weakness. (Photo Courtesy Ireland Engineering)

Aftermarket rods such as these H-beam units are both stronger and lighter than stock. During your planning, look for the lightest parts you can afford that handle your power goals. (Photo Courtesy Ireland Engineering)

it makes good power for its size. Internally, there is not much to do to this engine. You can rebuild it, but it’s hard to justify the expenditure when many other engines can be installed with such little difficulty. The M50 and S50, for example, both have the same bellhousing bolt pattern and orientation as the M42 and are an easy swap with more than 200 hp. But, if you keep the M42 and spend the money to rebuild it, there are things you can do. First, the M44 short block is interchangeable with the M42 (although the heads are different).

The factory M20 connecting rods are probably the weakest point in the engine. They do not take to extended high revs or lots of boost. They are also quite heavy. (Photo Courtesy Ireland Engineering)

The later 325i head is the one to use for a per formance M20 build. Don’t waste time or money on a 325e head with its smaller valves and fewer bearings.


8

The valves are larger in the i head and it has much more power potential. For the ultimate M20, combine a ported i head with a stroker crankshaft, slightly higher compression, and some porting. (Photo Courtesy Ireland Engineering)

The oil gallery holes are drilled to use an eta head with a 325i camshaft or most aftermarket camshafts. Because the stock eta cam does not have all seven cam bearing surfaces, only four cam bearings are drilled. (Photo Courtesy Metric Mechanic)

Forged Mahle pistons are an excellent choice for a performance M20 build. They are good quality, light, and precise. (Photo Courtesy Ireland Engineering)

9

The markings on this piston indicate that it is for a stock M20B25 with 8.5:1 compression. (Photo Courtesy Ireland Engineering)

This gives you the option of starting with 1.9 liters of displacement instead of 1.8. S50B30 pistons are interchangeable and give you a larger bore (86 mm), although the maximum overbore of the M42 is limited by its narrow bore spacing. The 1.9-liter crank combined with an 86-mm bore gives a 2.1-liter M42, which is the largest size possible for this engine. The larger valves from the S50 can also be used.

Supercharging and Turbocharging If you aren’t happy with the power levels you are able to coax from your E30’s factory engine, there is one option before considering an engine swap. That’s forced induction—generally, turbocharging or supercharging. There are a few turbo kits available for the M10, M20, and M42, but most require at least some engineering on your part. A turbocharger uses an engine’s exhaust gases to drive a compressor that forces air into the engine’s intake manifold. This compressed air is denser than air in the surrounding atmosphere, so each time the intake valve opens, more air enters the engine than is otherwise able to get in. The biggest obstacle standing between a stock E30 engine and high-boost power levels is proper fuel and ignition control. Turbo-


charged engines have different fuel and ignition requirements than normally aspirated ones and some way of modifying or getting around the stock engine controls has to be used. The stock M20 bottom end is good for a low-boost (under 8 psi) setup, but if you want to make more than 200 hp at the wheels, you need to install at least a set of forged pistons. While you have the engine torn down, don’t spend money on exotic cams and fancy valvetrain parts. Turbos make boost only when an engine is under load, so a high rev limit isn’t really necessary. Do spend money on decent head gaskets ( not Victor Reinz, which are notorious for leaking), sturdy aftermarket pistons, and head porting. The more air the engine flows, the more power it makes with the same boost level. When it comes to deciding on a compression ratio to run with a turbo, there are two schools of thought. The first is to run as much compression as possible, and only as much boost as absolutely necessary to achieve your desired power level. The other group is the “low-compression, high-boost” camp; build an engine with compression less than 8.0:1 and boost the crap out of it with a huge turbo. The high compression gives the engine better pull out of low-speed corners but limits the amount of boost and timing that can be run before detonation causes problems. A low-compression engine, on the other hand, can run more boost and timing with the same fuel and is able to make more high-RPM power. Consider dyno tuning a fairly important step in building a bucksdown turbocharged engine. Dyno time is inexpensive enough now so there is really no excuse for doing without it.

It takes a lot of crankshafts to find good ones to build stroker kits. Ireland Engineering keeps enough around to meet demand. (Photo Courtesy Ireland Engineering)

A good engine starts with a precise, accurate, and well-machined bottom end. Pick your machinist carefully, because his or her quality of work affects the power and lifespan of your engine.


10

1988 325is W I DE-BODY T URBO

You don’t always need to have an unlimited budget to to build a fast and trick car. That’s the overriding theme of the Grassroots Motorsports $200X challenge, an annual event where teams compete to see who can build the fastest car on the drag strip, autocross, and show field—all for less than $2,000.

88

E30s are common at the GRM Challenge, and this car built by the Condor Speed Shop is an excellent example. The team took it to four GRM Challenges, and finished 3rd overall in the last two, taking 2nd place in the autocross both years. In 2011, the car was invited to

participate in the Ultimate Track Car Challenge at VIR, and was modified far beyond the $2,00 budget. In its final form, the E30 finished 4th fastest in Group B. The car was tuned by DIY Autotune, and achieved 356 RWHP at 15 psi. According to the builders it is reliable and fast.


1988 325is Wide-Body Turbo Engine

2.7-liter block with a mildly ported 885 head Ported 524TD exhaust manifold Holset twin-scroll HX35 Ported OEM intake manifold with 36 lb/hr injectors Lightened flywheel with Sachs heavy-duty pressure plate and 4-puck clutch Custom 3-inch turbo back exhaust Front-mount intercooler with custom piping HKS SSQ blow-off valve Spal fan ARP head studs and Cometic MLS head gasket Suspension Ground Control complete coil-over suspension including camber plates, rear solid shock mounts, and front strut housings with M3 sway-bar endlink conversion Custom-valved Bilstein sport shocks and Eibach springs 325IC front swaybar Solid Condor UHMW motor Mmounts, transmission mounts, and rear subframe mounts Toe and camber correction bolts in the rear Condor power steering delete Interior AEM wideband air/fuel and boost controller gauges Autometer oil-pressure and water-temperature gauges Push-button start DIY Autotune PNP Megasquirt dyno G-Force 5-pt Camlock harness and mounting hardware Custom harness bar Kirkey race seat on modified factory sliders Carbon gauge panel Chassis 2,160 pounds One-off wide body made from OEM metal panels 1 of 3 fiberglass front bumpers 16x10 Diamond Racing wheels 20-mm front wheel spacers Goodyear Race Slicks, 23.5 x 10.5 x 16 Gutted hood, trunk, and doors Removed sunroof and cartridge Removed all unnecessary wiring Lexan quarter-panel windows, rear window, and sunroof cover Completely tucked engine and chassis wiring harness

With its wild paint job and box flares, this race car doesn’t look much like an ordinary E30 any more. It takes a lot of bodywork to keep big autocross-spec tires under the fenders of a relatively narrow E30, but it can be done. (All Photos Courtesy DIYAutoTune.com except top and middle photos on this page: Courtesy Kevin Adolf)


89

With its custom pistons and crankshaft, the Ireland Engineering M20 stroker kit results in 3.1 liters from an 89.6-mm stroke and 1-mm oversize pistons. This is a very good kit for a street-driven M20, since it is undetectable from the outside yet increases power nearly 20 percent. (Photo Courtesy Ireland Engineering)

There is nothing sweeter than a clean, rebuilt engine ready to drop into your car. A well-built one can give you thousands of miles of pin-you-back acceleration and spirited performance. (Photo Courtesy Metric Mechanic)

13

If you decide to build your own setup, you actually don’t need anything exotic. A simple U-shape adapter from the factory exhaust manifold outlet to a turbo flange is all that’s needed for a simple M20 turbo. Especially on a street car, the most important characteristics of a turbo manifold are heat resistance and strength. The best-known suitable material to create a manifold or adapter are thick-walled, cast-steel tubing shapes known as “weld-els,” which are available from industrial supply houses. The oil pressure feed line to a turbo does not have to be very large. An AN -4 (1/4-inch inside diameter) hose taken from the oil pressure sender port usually does the trick. The drain line should be short and as straight as possible. It should also be large in diameter, at least 1/2 inch (AN -8) or so. If you simply bolt a turbo to your M20 and hit the road, there is no control of the boost level. Boost increases to the highest level allowed by the intake and exhaust restrictions of the engine and the turbo’s capacity, and stays there, leaving a trail of broken parts on the road behind. Modern turbo engines use a small valve called a wastegate to divert part of the exhaust gases around the turbine impeller and back into the exhaust stream. The wastegate opens when boost hits a preset value. Most wastegates are flapper valves operated by a diaphragm canister. The most common OEM variety is cast integral with the turbine housing and turbocharger outlet. While most have a preset boost level, they can be easily fooled by a simple bleed orifice in the line that feeds pressurized air to the diaphragm. Wastegates can also be con-


Turbo engines require a lot of plumbing to move pressurized air around. It’s not hard to fabricate your own, even if you are trying to squeeze all that tubing under the hood of a 2002 with an M20 stuffed in it! (Photo Courtesy Ireland Engineering)

The turbo drain should be installed as low as possible yet above the oil level when the pan is full. This is a good spot. (Photo Courtesy Ryan Gangemi)

trolled by complicated electronic or mechanical boost-control valves that allow boost to build quickly before stabilizing. Selecting the properly sized turbo for a given engine seems more difficult than it is. There are many ways

to approach this, depending on whether you intend to use an “offthe-shelf” turbo from the junkyard with a quickie rebuild or buy a new or rebuilt custom turbo. Any good turbo book (such as TURBO by Jay Miller) can take you through the

process of calculating your engine’s airflow demands, target horsepower, and turbo flow requirements. There are small, local turbo shops that specialize in building custom turbos from OEM parts to fit a new application. A quick check of the Internet tells you who is trustworthy and who to avoid. Most turbo installations make use of an intercooler to drop the temperature of the pressurized air going to the engine. Air-to-air intercoolers come in a baffling array of sizes and shapes. A fabricator handy with aluminum should be able to weld up just about any shape necessary using commercially available cores and sheet-aluminum end tanks. Many people have successfully “fooled” their stock EFI system by installing larger injectors or increasing base fuel pressure. As long as the change is no more than 10 percent or so, this can work well. At idle and low speeds the original ECU (using feedback from the oxygen sensor) determines that the mixture is richer than expected and shortens the injector pulse width to compensate. At higher loads, the built-in fuel tables, combined with the larger injectors or higher fuel flow, give the engine more fuel with the same pulse widths. The problem with this strategy is the limited correction possible. Turbocharging a stock engine probably outstrips the ability of larger injectors to supply enough fuel with the stock programming at very low boost levels. Something more complex must be done to compensate. If you want to maintain your stock ECU and don’t have a way to reprogram it, consider modifying the vane airflow (VAF) signal with one of the aftermarket boxes such as the Greddy EFC or Apex’i AFCI. For


14

This beautiful manifold is designed for a turbo with an external wastegate, which is better in many applications. An external wastegate is less likely to suffer boost creep, when boost increases beyond the preset levels because the internal wastegate is not large enough to let all the exhaust out. (Photo Courtesy Ryan Gangemi)

moderate changes, these systems can “bend” the signal enough to keep the engine fueled. Such signal modification is fairly limited. Within a few percent, signal modification works, but you can quickly run into a situation where the required signal modification does more harm than good. The most sophisticated solutions

to the fuel control issue require a working knowledge of electronics and software, but the skills aren’t difficult to learn. The same techniques that you might use to tune a normally aspirated engine work for turbo engines. This is impossible with the M10 but easier with the M20 and M42. If you can convert to a speed-density system (using a man-

Dollar for dollar, porting your head produces more power than any other modification. Power gains can be huge if the porting is done well. (Photo Courtesy Ireland Engineering)

15

The exhaust is important as well, particularly on a turbocharged engine build. Make sure that your head por ter has experience with the M20 head because misguided grinding can actually reduce flow. (Photo Courtesy Ireland Engineering)

ifold air pressure [MAP] sensor and doing away with the AFM), so much the better.

Engine Swaps The M10 and M20 engines are designed around old technology and the M42 engine is hampered by a small displacement. Turbocharging

The intake ports are the most important from a power standpoint. The final finish of the port is not nearly as important as the shape of the port, however. (Photo Courtesy Ireland Engineering)


A bypass valve or blowoff valve is located in the intake tract of a turbo engine and is often mistaken for a boost control device. Its purpose is not boost control but rather to eliminate boost spikes between shifts that can cause the turbo compressor to stall. (Photo Courtesy Ryan Gangemi)

is not a valid option in some states (such as California). That leaves one last option for increasing the horsepower of the E30: an engine swap. Luckily for BMW enthusiasts, the company has used only a few different bellhousing bolt patterns and engine mount locations over the years. But before you get too excited, remember that any engine swap is a custom endeavor; even if it’s been done 1,000 times before, there are always small details that trip you up during the install process. What works for one car may not work for another, because of differences in engines and chassis.

The M3’s S14 engine is a highly tuned piece of machinery and parts prices reflect this. There is no cheap stroker option as there is with the M20 sixcylinder family.

Some people prefer to keep the fourcylinder, and for them there are larger engine kits, bigger cams, and ported heads available. (Photo Courtesy Metric Mechanic)

If you have a worn M42 engine, it makes more sense to swap it for something else than to keep it. There isn’t much power hidden in the little four-cylinder and swapping to a more powerful six is not very difficult.


16

By far, if the budget stretches to a new turbo, the easiest way is to simply call one of the custom turbo manufacturers and tell them your engine combo, driving conditions, and some other bits of key information and let them recommend a turbo to you. (Photo Courtesy Ryan Gangemi)

This turbocharged M20 has a smaller (and easier to package) water-to-air intercooler visible in the upper right of the picture. (Photo Courtesy Turbo Charging Dynamics)

Ryan Gangemi’s turbo setup uses an air-to-air intercooler mounted behind the front bumper. An air-to-air intercooler is probably the best setup for a street car. Just try to make your installation this clean. (Photo Courtesy Ryan Gangemi)

17

With the water-to-air intercooler, this car made more than 300 hp and could lay down quarter-mile times in the 11-second range. Not bad for “just” an old BMW! (Photo Courtesy Turbo Charging Dynamics)

The most flexible option for controlling the fueling of a turbocharged engine is an aftermarket EFI system. A laptop and a closed track are all you need to get started.


How about a little more than 3 00 hp? This is with a relatively simple turbo setup on a built M2 0B25 engine. (Photo Courtesy Ryan Gangemi)

The only E30 engine for which a supercharger is an easy option is the M42. Downing Atlanta makes a supercharger kit that costs about $3,800 and makes about 200 hp at the crank, or roughly 170 hp at the wheels. It’s a solid, wellengineered solution but, unfortunately, is available only for the M42 engine. (Photo Courtesy Grassroots Motorsports/ David Wallens)

The E30 engine bay is large and many engines, both BMW and nonBMW, have been swapped into it over the years. The BMW V-8 and V-10 swaps, while impressive, are difficult and the power advantage is not as great as the complexity of the swap. Since an engine swap requires so much time and work, it does not make sense to swap in an engine that is only slightly more powerful than the E30 engines, such as the M50B25 and 28. Generally speaking, the best engines to swap into the E30 are the E36 M3 engines, S50B30, and S52B32. Both produce enough power The M20 engine, with its low compression and strong bottom end, loves boost. to make the swap worthwhile. The simplest way to swap these A decently sorted turbo setup with an intercooler, proper engine management, engines into an E30 is to use the and boost control can make more power t han any engine swap. (Photo CourECU and wiring harness from a tesy DIYAutoTune.com) pre-1996 325i, since this harness is simpler than the M3 harness Unfortunately, this conversion sible, but there are numerous small that normally runs these engines, is not a simple electronics swap. details that have to be addressed— which has EWS (anti-theft). This Nearly every sensor on the engine and this is before even beginning also converts the engine from OBD- and many hard parts, such as the the process of installing the engine. II to OBD-I, which adds power and intake manifold and fuel rail, must The only oil pan that fits an E30 reduces complexity. be changed as well. It’s not impos- must come from an E34 535i, as no


18

Here’s another example of what a turbo M20 is capable of. This engine, controlled by the DIYAutoTune PNP Megasquirt ECU, laid down more than 340 hp. (Photo Courtesy DIYAutoTune. com)

The MicroSquirt-based computer system makes a pretty attractive choice for a turbocharged engine build. For the price, the features and reliability are impossible to find elsewhere. (Photo Courtesy DIYAutoTune.com)

This is what a 300-hp M20 engine looks like. No frills, just the bare necessities of power production and boost control. (Photo Courtesy Ryan Gangemi)

19

While the cheapest commercially available systems cost upward of $1,000, there is at least one that can be built at home for much less. The DIYAutoTune PN P system replaces the factory Motronic ECU. (Photo Courtesy DIYAutoTune.com)

An hour or two of dyno time and the advice of a good engine tuner are definitely cheaper than broken parts and easier than fighting with intermittent drivability issues. A dyno pull is always good for showing the weaknesses in a setup. (Photo Courtesy DIYAutoTune.com)


other oil pan has the sump in the right location to clear the subframe. For reference here are the parts needed to swap the oil pan: You don’t have to buy new parts, but they can be hard to find since there is only one car that can donate them. The other necessary parts are E36 mounting ears (these should have come with the engine if you are using an S50 or S52 from an M3). The S50/S52 engine bolts to the E30 Getrag transmission using the stock 325i clutch and single-mass flywheel. However, your transmission will be at a 10-degree angle to the right and will require some modifications to the transmission mount. If you use an E36 Getrag 250 you will not have to modify the transmission mount. Once you have an engine and wiring harness you can begin installation. The brake booster on an E30 does not clear the intake manifold, so you have to swap to an E21 booster or a Porsche 944 booster. The E21 booster allows you to retain your stock master cylinder.

The later 3-series engines, the M50 and S5 0 family, are relatively easy to swap into an E30. This car has an S50 from a pre-1996 E36 M3.

With around 240 crank hp, the S50 and later S52 make great E30 powerplants. There are some tricks to the swap—mostly electrical, but they are straightforward and well documented. The E30 driveshaft is a two-piece driveshaft with a rubber coupling and single U-joint for the front half, a solidly mounted center support bearing with a section of sliding splines in the middle, and a rear U-joint. The center support bearing and front rubber flex coupling are replaceable but the two U-joints are swedged in place in the factory driveshaft. (Photo Courtesy Vorshlag Motorsports)


20

The exhaust system has to be custom made (the E36 M3 manifolds will clear the E30 chassis with some tweaking); the right control arm bushing, sway bar, and rear crossmember are the tightest points. The rest of the exhaust (or at least the part that connects to the E30 tail pipe) has to be custom made. There isn’t enough room in this book to cover every single detail of an M50/S50-type swap but this should give you enough information to start your own research to determine which parts are needed for your particular combination of engine and transmission.

550/552 Oil Pan Swap Parts List

The S38B38 “big six” engine from an E34 M5 can be swapped into an E30 but it is not an easy swap. The engine weighs about 100 pounds more than an M20 and the mounts, driveshaft, plumbing, and electronics all have to be fabricated.

The S54 from the E46 M3 is rated at 330 hp. Its size, light weight, and power make it an attractive E30 swap candidate. However, it is not an easy engine to install. This M3 proves it can be done. The S54 fits neatly in the E30 engine bay. (Photo Courtesy Ryan Gangemi)

21

Oil pan Oil sump gasket Oil pickup tube Dipstick Dipstick tube Dipstick O-ring

PN 11-13-17-40-346 PN 11-41-17-03-947 PN 11-41-17-48-150 PN 11-43-17-20-875 PN 11-43-17-38-169 PN 11-43-12-87-541

Hard urethane engine mounts can make custom swaps easier by maintaining tight clearances between the engine and parts of the chassis. They can also be modified to situate the engine at any height. (Photo Courtesy Vorshlag Motorsports)


Here’s another angle showing just a tiny bit of the fabrication needed for this swap. Additionally, the engine has a very complicated ECU that must be modified or replaced.

This shot tells a different story. The entire E30 subframe has been cut away and a tube replacement made. (Photo Courtesy Ryan Gangemi)

Not only has the car been modified, the factory S54 oil pan has been extensively modified to clear even the minimalist new crossmember. (Photo Courtesy Ryan Gangemi)


22

CONTENTS

Foreword by Satch Carlson .................................................... 4 Introduction .............................................................................. 5 Chapter 1: E30 History and Development ........................... 6 Evolution of the E30 ........................................................... 7 Manual Transmissions ....................................................... 12 The E30 Today ................................................................... 14 Chapter 2: Buying an E30 ..................................................... 15 What to Look For .............................................................. 17 Exterior and Interior.................................................... 19 Engine and Drivetrain.................................................. 24 Take a Test Drive .......................................................... 24 Buying an M3 ..................................................................... 26 Buying a Modified Car...................................................... 27 Buying a Race Car ............................................................. 29 I Own an E30; Now What? .............................................. 30 Chapter 3: Suspension, Steering, Brakes and Differentials.......................................................... 32 Suspension Modifications ................................................. 35 Lowering ....................................................................... 38 Springs and Shocks....................................................... 41 Sway Bars ...................................................................... 48 Tires and Wheels .......................................................... 51 Bushings and Mounts .................................................. 54 Suspension Reinforcements......................................... 57 Steering ............................................................................... 59 Brakes.................................................................................. 62 Chapter 4: Engine ................................................................... 71 M10 Four-cylinder............................................................. 71 M20 Six-cylinder................................................................ 72 S14 Engine .......................................................................... 76

M42 Four-cylinder............................................................. 77 Bolt-on Modifications ....................................................... 78 Internal Modifications....................................................... 82 Supercharging and Turbocharging ................................... 90 Engine Swaps ..................................................................... 97

Chapter 5: Drivetrain........................................................... 100 Clutch ............................................................................... 100 Flywheel ........................................................................... 101 Manual Transmission....................................................... 102 Automatic Transmission ................................................. 102 Driveshaft ......................................................................... 104 Transmission Swaps ......................................................... 104 Differentials and Gearing ................................................ 110 Chapter 6: Restoring the E30 ............................................. 115 Basic Exterior Care .......................................................... 117 Trim Pieces ....................................................................... 119 Bumpers and Grilles ........................................................ 121 Exterior Paint ................................................................... 125 Rust Repair ....................................................................... 127 Interior.............................................................................. 127 Dashboard................................................................... 127 Upholstery .................................................................. 128 Headliner .................................................................... 129 Carpet.......................................................................... 129 Seat Swap..................................................................... 132 Interior Electrical ....................................................... 135 Odometer Repair ....................................................... 136 OBC Swapping........................................................... 136 Chapter 7: Racing the E30................................................... 137 Source Guide ......................................................................... 144


BMW e30 engine mods

Recommend Documents