Can Can
Can,
Most of what you're asking centers around decisions that must be made logically. Many of the parts work together to achieve a certain level of horsepower. Parts chosen without that premise will end in buying others needlessly.
There is nothing wrong with either triple or FI. Another decision is how you want the engine to look. The early FI engines can be modified for an old school look with modern performance. ( L-Jet conversion to Motronic 1.3 or Mega....)
Last but not least is cost.. and I haven't heard what you're starting with other that carbs to FI back to carbs.
Here's someone else's view,
"
The pathway to a high-power M30 depends on the end-goal. The 3.5 liter racing motors in the 70s produced nearly 400 bhp, but are anything but streetable. Whereas the last incarnation of the production M30 had 208 bhp (US) and was a very smooth operator in the 3600 lb E32s.
For the purposes of this article, we will divide the ‘horsepower goals’ into 4 divisions: 210-240, 240-260, 260-280, and 280+. 210-240 bhp is a reasonably easily achievable goal without a large outlay of cash.
A few options include the following:
Options for 210-240 bhp range:
Start with a euro B34 high compression motor or a B35 motor. Modifications include: Headers and full dual 2” exhaust, B35 intake manifold with port matching, larger throttle body, 19 lb-hr injectors, updated chip. Reasonable estimate of power is 230-240 bhp. Hartge and Alpina were able to get this type of power using Motronic and L-jet in the 80s, keeping the stock displacement. Other options include a MAF. Similar figures can be obtained from a M30 B35, albeit probably not quite as high due to lower compression ratio. 230 bhp is a reasonable estimate in terms of bolt-on modifications for a B34 HC or B35 motor. The best that a B34 low-compression motor can do with simply bolt-on modifications (chip, exhaust, intake, injectors) is perhaps about 200-210 bhp. The problem is that upgrading the cam will not benefit you due to the low compression.
Typical costs (estimated total: under $2000):
Header: $500 + additional fitment work downstream
B35 intake manifold: $200
Chip: $200 (new)
Injectors: $250 (new)
MAF: $600-1000 (new, est.)
Options for 240-260 bhp:
This range of power effectively requires head work, and preferably a bump in compression ratio. Ideally the compression ratio would be 9.5:1 or higher (the euro B34 already has 10:1, but the B35 has 9.0:1). Running a stock chip on either the Motronic 1.0 from the euro B34 or the Motronic 1.3 (recommending the 179 ECU) is probably reasonable if your compression ratio bump on the B35 is only to 9.5:1. Headwork ought to include the standard larger intake values (47mm) and preferably the exhaust valves (to 38mm). A camshaft is a must, preferably 284 degree Shrick or equivalent. Replacement of valvetrain components is always recommended. Porting and polishing the head is also recommended. At this point the B35 intake is recommended, although Alpina claimed 254 bhp using the holder style intake. Headers are a must, as are dual 2” exhaust all the way. MAF conversion is a good option, as are big-bore throttle body. Note, both Alpina and Hartge used >10:1 compression to get over 250 bhp. And Alpina used Motronic 1.1/1.3 on its later motors with 254-260 bhp.
Typical costs (estimated total: $5000-$7000):
Header: $500 + additional fitment work downstream
B35 intake manifold: $200
Chip: $200 (new)
Injectors: $250 (new)
MAF: $600-1000 (new, est.)
Camshaft: $400 (custom grind)
Head work: $2000-3000 (see Top End Performance website)
Pistons: $1000 (see JE Custom pistons)
Wiring harness and ECU: $400 (used, estimated)
Throttle body: $200 (service, based on Big Coupe Group list)
Options for 260-280 bhp:
On top of what was said above, now’s the time to consider a full B35 intake, 47/39mm valves, increased displacement, dual 2.25” exhaust and headers, big bore throttle bodies, 24 lb-hr injectors, and FI system updates/modifications that can include going to a newer Motronic, custom chips, MAFs, or other options. Over 10:1 compression is a must in these cases. Reworked combustion chamber shapes, a la Alpina, can also be considered in this case.
Typical costs (estimated total: $7500-$10,000+):
Header: $500 + additional fitment work downstream (more than $1000)
B35 intake manifold: $200
Chip: $200 (new)
Injectors: $250 (new)
MAF: $600-1000 (new, est.)
Camshaft: $400 (custom grind)
Head work: $3000-4000 (see Top End Performance website)
Pistons: $1000 (see JE Custom pistons)
Wiring harness and ECU: $400 (used, estimated)
Throttle body: $200 (service, based on Big Coupe Group list)
Tuning services: varies
Suggestions for 280 bhp+:
On top of the above: increased displacement and mild stroking, reworked combustion chambers, individual throttle bodies. At this point, 10.5:1 compression is probably required, as well as custom-tuned FI system. MAFs are highly recommended.
Typical costs (estimated total: $10,000+):
Boring motor: $400-600 (estimated)
ITBs: $600 for adapters, $500 per pair of ITBs, estimated $600-800 in additional components (fuel rail, plenum, etc)
‘Clean sheet’ option:
However, for the purposes of this whitepaper, we will assume to start off with an M30 B35 motor, and build a streetable, reliable, but high horsepower M30. Let’s take for example the E34 535i, or a late E24 635CSi. Concentrating on the block, there is not much you can do with stroking, but there is a lot you can do to bore the motor. There is the option of using a 3.8 S38B38 crank, or machining your own custom crank to stroke a motor. However, an M30 already develops boatloads of torque, so the better option in this case is to bore it to increase displacement and thereby concentrate on making more horsepower rather than torque. The options to boring are basically anything between 92 and 94.5mm (S38 B38 specs). It is known that the S38 B38 had some cylinder wall thickness issues, so maxing out at around 94mm bore is probably preferable. Of course you can use 93.4mm and keep a stock BMW dimension (e.g. S38 B36 specs). Therefore, Custom JE forged pistons that raise the compression to at least 10:1 and have a 94 mm bore. Raising compression is going to be a function of fuel use and head work. If you're using a B35 head and premium fuel, you can probably safely raise compression to around 10.5:1 (Alpina had these ratios in the mid-80s, but with a highly reworked combustion chamber.). If fuel quality is a question, or you don't want to be too aggressive, then 10.2:1 to 10.4:1 is a very reasonable compression ratio for these motors, especially if you are using a piano-top style piston profile as opposed to the heavily reworked Alpina style cylinder heads and pistons. However, the stock Motronic 1.3 will ping if you bump the compression by 1.5 points, therefore you will need to retard the timing that BMW built into the 1.3 with 9:1 compression.
Recommended Top End Performance can get JE Custom piston with Total Seal Rings which are far better than BMW's rings with just about any shape and compression ratio you want. They have blueprints and records and can do anything you want. Now, radius the con rods as that will increase strength. Of course I suggest using new con rods bushings and bearings. Custom, strengthened, and lightened con rods are available from Top End, should you go this route. Use the stock 86 mm stroke crank, but have it cross drilled and rifle bored, if you can. This will increase low end oil pressure and also the life of your rod end bearings which is a good thing because you will be making a lot of power. Now, you start to assemble the bottom end. Pistons, rods, crank. Then you get to the oil pump. You need to use an E28 oil pump because without it, you will not be able to bolt on the E28 oil pan which is necessary to clear the subframe in an E28 or E24 (that is if you're starting with a E34 or E32 engine). Now you have the bottom end built. I suggest using a lightened flywheel also from Top End Performance. 15lbs is light enough and an M5 clutch should do you. There have been people who’ve gone for 12 lb or lighter flywheels with success, albeit these are non-AC equipped cars. The later Motronics can probably handle the idle better too if you go for that light a flywheel.
Now that you have the bottom end together, it is time to work on the top end. Let me just say, that with the bore increase you will have a 3.58L motor. Also please don't forget it is important to use the E28 motor mounting arms so you can bolt the block to the subframe. I also suggest using 2 of the left side motor mounts from an M5 as they are stronger than the stock units (or the M535i mounts as those should be the same). Be sure you do not ‘He-Man’ torque them, as this will shear the rubber mounts. Speaking of torque specs, it is vitally important that one follows them! Do not under any circumstances over or under torque critical fasteners such as on a motor. Always follow the BMW torque specs.
As for the head, use a stock B35 head to start. It’s now time to invest in machine shop experience, and begin by skimming it to make sure it is flat. Port and polish it, and also do a three angle valve job – most engine builders who specialize in older BMWs and race motors can effectively do this service. Depending on what cam you are running you might want larger valves but I think that the 47 mm intake and 38 mm exhaust are just fine (although 47mm / 39mm will do you well too). Top End Performance again has loads of experience here and can make custom stainless steel valves for you. Anything larger than 47 / 39 will require custom valve seats and more headwork to get them to fit correctly. New guides, seats, etc. are a must. Then radius the (new) rockers which will give them added strength for the extra duration and lift of the cam. Now I suggest using Metric Mechanic progressive rate valve springs (Edit: the dual valve springs from MM are no longer available, and thus we'd recommend going with dual valves springs that Top End sources) and also their head oiling upgrade kit (which is a crimped oil sprayer bar to improve oiling a the cam). You can use titanium retainers if you like, depending on the RPM you’re expecting out of the motor this might be more or less beneficial. You can use pretty much any cam you want, but I suggest not going below a 280. Using a Shrick cam design (284 or 292) on a custom grind is preferable. Top End can provide these, as well as almost any other good engine shop with experience in BMW motors. An adjustable cam gear will let you advance and retard your cam for better performance or better economy. This might be particularly useful in final tuning.
For the head gasket, I believe you can use the early big six, with the 93.4mm bore gasket, but I would suggest getting a custom one with a solid metal ring in it so that you have less chance of blowing the gasket. These are again available at almost any good custom engine builder shop specializing in BMWs (e.g. Top End). MLS gaskets have also been recommended, but have a strict requirement for surface finish RA. Cometic have a good product that works well with older motors, particularly M30s.
On to the intake and exhaust... For the intake I would suggest starting with the E34 M30 B35 intake, and then port match it to the head. Extrude-hone will cost a pretty penny, but will give you the maximum flow possible out of the stock casting. As for the exhaust, custom headers are in order that have 1 1/2" ID primaries that go into dual 2" collectors at minimum. Custom track pipe to mate up with the collectors and I'd recommend an E28 M5 exhaust if possible. These exhaust dimensions are basically the minimum you can run...although it'd be preferable to run something slightly larger. A good tuning book (e.g., A. Graham Bell's "Four Stroke") should offer some insight into a custom exhuast. You should also be able to use the E24 M30 b35 intake bracket to support the intake to the block.
There are two options for a individual throttle body system. The first is to attempt to retrofit the M5 intake system. This requires at a minimum fabricating adapters from the head to the M5 intake runners. It also requires investigating the choice of fuel rail, as the M88 or S38 rail and FPR will not clear the t-stat housing on the M30. Similarly, the TPS switch will have to clear the t-stat housing. To do this the adapters have to be angled so as to point the intake runners above/below the t-stat housing and rad hose. The other option is to get the Weber DCOE adapter brackets from Redline Weber (Redline Weber part # 99004 094). The castings aren’t that great, so porting and polishing them is a must. However, 40mm or 45mm Weber fuel injection ITBs can then be bolted onto these. Again, one of the flanges near the t-stat housing has to be shaved a bit to clear, and I have not verified if the TPS switch will clear the t-stat housing and rad hose, but this looks to be more a ‘bolt-in’ solution. Additionally you’ll need a custom intake plenum.
http://www.jameng.com and
http://www.twminduction.com are both good sources for the ITB components, as well as Top End Performance can order anything from Redline Weber.
Fuel system and engine management: Use either custom engine management (Megasquirt, etc.) or Motronic 1.3 out of the late '88 and '89 E24, along with the engine harness. Update the ECU to #179 (#150 is Motronic 1.1). This is because the Motronic unit will then mount in the same place as the one currently in the car, and Motronic 1.3 is adaptive enough to run this motor well. It is necessary to retard the timing a bit as the 1.3 was set by BMW with 9:1 compression, although this seems to be an issue (pinging that is) at lower rpm, high load conditions, for engines with ~9.8:1 compression or higher. I would then suggest a dyno day and a custom burnt chip. As for fuel system, I suggest running Mustang 24 lbs/hr injectors at minimum at 3.0 bar, but depending on your fuel requirements you may need to up that to 27 or 30 lb/hr. The Bosch Motronic 1.3 in limp-home (open loop) mode with the 179 ECU and 24 lb-hr injectors runs my (Chris’s) engine around 11.8-13.0:1 AFR, or very rich. Idle is right around 14-14.5:1, and off-idle there is no hesitation. And the 3000 - 3500 rpm range is butter smooth. Cam seems to ‘come on’ around 3700 rpm, although after 100 miles of break in I’ve not yet gotten past 4000 rpm, nor gotten past ½ throttle.
I would also suggest using a big bore throttle body because you will need as much air as possible. On this note, a Mass Air Flow Sensor conversion is in order as it will give the engine management more precise readings and also will be less of a restriction, in theory. There are and have been a number of options for MAF conversions for Motronic systems. However, it is important to note that a MAF will not in and of itself improve outright power, given similar flow conditions at wide open throttle vs an AFM. That isn't to say a well operating AFM isn't good as is - one has to remember that BMW used a AFM on the euro M5/M6 to great effect to get 286bhp. The E34 M5 3.6 increased power to 310 bhp, but included improvements to the head, increased displacement, a more complex intake resonance system, and better engine management system with O2 sensor feedback, all on top of going to a MAF. And the improvement was only 24 bhp. Alpina also got 260 bhp (DIN I believe, at the crank) out of their B10 3.5 liters using an AFM. The conclusion is that, in theory, a well operating MAF will provide better on/off throttle smoothness, and part throttle improvements. If you have a well operating AFM, unless one goes to standalone fuel injection system, it is not necessary to get a MAF. But in theory, a well operating MAF can provide some improvements over a AFM.
With regards to cone filters, their maintenance IS A MUST. Never leave a K&N or similar filter un-oiled. However, a stock air filter system works just as fine as well. Lots of work can be done here to 'dress up the engine bay' since a cone filter in and of itself will not do you much good in terms of power. Additionally, an oiled filter fitted too close to a MAF will ruin it in short order.
As for oiling system, I would try to run the euro E28 oil filter canister and housing because I would never run this motor without an oil cooler, which BMW's bolt on approach here will work just fine.
Rob and myself have built an engine very similar to the 'clean sheet' recommendations we have written above. These are a summary of the results as of October 2007: Engine rebuilt with following specs:
• M30 B35 out of E24
• 10.45:1 custom JE forged pistons, total seal rings
• M90 head gasket
• Bored to 93.4mm (3535cc total)
• New con rod bushings, bearings, main bearings, etc; rods and pistons balanced to within 0.7 grams of each other
• 15 lb Top End Performance flywheel
• Larger, stainless steel valves (47mm / 39mm)
• Ported and polished intake and exhaust ports
• 3-angle valve job; new seats, new seals, etc.
• Metric Mechanic peened rocker arms
• 294 deg custom ground cam (Top End Performance, style 290MM)
• Dual valve springs, titanium valve retainers
• All new valvetrain components
• Hartge Headers (yet to be installed)
• Custom, dual 2.25” exhaust with high-flow catalytic converters (yet to be installed)
• Motronic 1.3, with custom burnt chip (Mark D’Sylva)"
One of the early decisions unique to E9s is brake booster clearance. Other than the original Ljet manifold, every other induction choice requires a smaller brake booster so everything fits.
Keep asking questions and I'm sure we'll all have opinions.
