3.5 donor

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acat2002

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Over this winter, I'm strongly considering a 3.5 & 5spd swap for my '73 CSA.
Specifically looking for the '88-94 735 or '89-94 535 for Motronics/wiring loom reasons.

I've been noticing no shortage of '89-93 535i cars (some w/5spds) for between $800 and $4000). Since finding one with under 100,000 on the odo would be like finding a virgin in a whorehouse, I'm wondering if I'd be better off finding a very tired example for short money and spend the real money on a solid top/botom rebuild of the 3.5

So say for example, I found an entire donor car for $1,000 but w/ tired or suspect engine, what would a GOOD rebuild cost? I'm in the New England area and don't plan on sending the motor to CA or some world-renowned specialist who builds race cars. No race specs, just standard bottom & top end rebuild by a seasoned BMW shop resulting in a fresh 3.5?

My theory is I'd be better off going the rebuild route as opposed to spending tons of time looking for the cherry example of a 20 year old car and living with unknowns while still spending $3-$4k on a donor.......spend short money on a 200k+ mile donor and throw the balance of the budget at the rebuild.

Has anyone had the same question? anyone gone down one path and wished they hadn't.
I'm just in the early due diligence/feasibility phase and wanted to hear some feedback from EXPERIENCED board members.
 
It depends on what you find

In my case, my mechanic found a great condition Euro high compression block from an '84 635 CSi that only needed new bearings, oil pan gasket and seals....we thought the head was in matching condition but that was not the case. The valve seals and guides needed replacement but, happily, local machine shops are looking for work now so I got my head restored and pressure tested for $400. Also, the cam that came with this head was a 300 lift which woulnd't work with my L-jetronic/Motronic 1.3 hybrid conversion, so we ordered up a 264 cam. The wiring harness came from an '89 635, one of the few cars I've heard that provides the length you need to avoid harness splicing.

Add a used Dinan chip to this all and I'm shooting for 240 hp.

In my case, if I had found a Euro 635 from '79 - '82, that would have been perfect, so I could have taken the CR gearbox and 3.07 rear end, along with the motor stuff, but we couldn't find suitable candidate locally.

Many folks will tell you hear that BMW engines, especially the blocks, are super durable and you have no problems swapping the whole long block with some minor changes (seals, etc). But it's likely any head with over 100K has some imperfections to it that will lead to problems down the road but I got lucky with needing a valve job only.

Good luck!
 
acat2002 said:
Has anyone had the same question? anyone gone down one path and wished they hadn't.
I'm just in the early due diligence/feasibility phase and wanted to hear some feedback from EXPERIENCED board members.
Click to expand...

Mechanics, like Doctors, see a lot of sick patients so they are not always the best people to seek advice from. I have been repairing exotics for 34 years.

The reduced maintenance schedules that most vehicle manufactures adopted years ago have had, IMHO, a very bad side effect. It is unusual to find a 100K mile car without enormous amounts of oil sludge underneath the valve cover. V8 BMWs are particularly bad about this. Most people push the envelope and stretch service intervals to a point where the overall engine health suffers.

That being said, I would find a reasonably priced motor and go through it from top to bottom. Anything else, I feel, is a crap shoot. With most cars being scrapped after 7 years the engine rebuilding business has dried up.
Many of the great automotive machinists I have used over the years are doing other things more lucrative. Manufacturers offer remanufactured long blocks for short money and the independents can't compete. I do not know if BMW has such a program or not.
I will check with some firnds in New England and get some names for you of good people.

David
 
E9Wayne & Bertocchi: thanks, both sound advice. I did not know that about the wiring harness in the 89 635 - good to know.

I explored this a few years ago and there were loads of opinions, including very specific donor cars that contained all the right bits. The 89 E24 (euro) sounds like it would be "the mother load". I've got plenty of time, my stock 3.0 has a rebuilt head and runs very strong, clean and smooth.

I'm just getting tired of the auto and even though the webers are rebuilt and tuned perfectly, I'd just like a little more. Bottom line is the current set up is fine, I'm just planning ahead.

I wonder if budgeting $2,000 for a complete rebuild is in the ballpark?
 
I did exactly what you are thinking about doing. Found a tired 3.5 out of an '85 535i and tore into it. The short block was still in great shape and just needed a good professional hone job. The crank got polished and the rods resized and rebushed. The whole bottom end was reassembled with a new oil pump, new bearings, Mahle flat-top pistons (intended for a big-bore VW type I motor) and a new timing set. The head was pressure checked and treated to a quick valve job. I added a Schrick cam and new rockers on the way by. Total parts were around $1,500 (the cam was $700 or $800 alone) and the machine shop work was around $600 or so. I reused the 3.0 flywheel to save weight. I assembled the whole thing myself and now have about 15k on it. With the lightweight rotating assembly it dynoed at 195 hp and 200 ft/lbs of torque at the rear wheels. It's even higher now after some additional tuning.

So, this is a viable and cost-effective option to get a HP motor -- especially if you can handle the assembly work. The key is to find a usable short block which doesn't need a ton of machining and custom pistons.
 
If you can't do the mechanic work yourself try Mario Langsten at Vintage Sports and Racing in Bow NH. I found a 3.5L from a 635CSi with low milage. Mario rebuild the bottom end, polished the exhaust ports, jet coated the manifold, and replaced the EFI with the twin Webbers (as I desired). Then a lightened flywheel was installed.
Cost about $4000.

Not cheap but the car runs great. Last week I went from Portsmouth NH to Augusta Maine and flew along the hiway with the engine purring.

See pictures of my car at E9-Driven.com 2240907


Stan
 
Thanks Stan, that is a very viable option. Though I hadn't assumed that VSR was an engine builder (guess I should have asked). I don't think I'd need the port work although I'd be tempted if it didn't blow the labor cost out of control. I'd probably stick with stock or mild cam as well. The purpose is to build a cruiser, not a rocket.

It's my understanding that it's extremely costly to squeeze the extra 20hp+ out of this motor. My old '91 535 had what, 225hp in US stock form (correct me if I'm wrong). That's all I'm looking for. Sure, if I can find a euro version or an S38, I'd get excited, but for now just weighing some options.

I tried to keep the initial thread question narrow, because we all know what happens if you ask something like "how much does it cost to do a 3.5 5psd swap on an e9" - one million variables, four thousand opinions and inevitably somebody gets their undies in a bunch.

I'll explore some other aspects later, but just wanted to get an idea of what it costs to rebuild (bore, new pistons, bearings etc.) a high-mileage b35 to mild specs. Sounds like if there's no mechanical armegeddon going on inside, we could be in the $2-$3,000 (parts, labor, sub-out machine shop work etc) without any special goodies like blueprinting/porting etc.?
 
Your $2,500 - $3,000 rebuild estimate sounds about right based on my experience. The M30B35 in the '91 535i was rated at 208hp and 225 ft/lb torque (vs. 182 hp for the earlier M30B34). That's at the crank, so you need to adjust measured RWHP accordingly. The M30B35 was rated at 9:1 compression ratio stock (compared to 8:1 for the M30B34). That, and bigger valves, makes it the best candidate for a rebuild IMHO. I would've used one, but a good used M30B35 was $1500 or so locally, whereas the M30B34 is a dime a dozen. You'll see significant power gains over stock with just the addition of a Shrick cam and no other internal mods - likely that elusive 20 hp that makes all the difference. I got about a 40 hp bump in bhp just from the flat top pistons, cam and headers. HTH.
 
I have an 86 535 engine that I intend to use one of these days. We were able to determine that the car had received good care before its demise and I am very confident about it's condition with "just" 100,000 miles on it.

Based on my 15 years' experience with my 635, I am more concerned with the engine electronics than I am with the mechanical bits. I would strongly urge replacing all the sensors and relays, as well as the Motronic control unit. I've had the following fail: main engine relay, fuel pump relay, control unit, and position sensor (twice).

The only mechanical part I have had trouble with was one $6 rocker arm eccentric. (That rocker could not be adjusted where the valve was not noisy.)

One thing to consider about donor engines is that few E9 owners (Murray excepted) are very likely to put many miles on their cars. I think I've put about 3,000 miles on my 635 this year and most of that was travel to two out-of-state events. So I am not very worried about putting lots of miles on my 3.5 conversion (which starts with just 100,000 miles).
 
As to M30 overhaul costs, my estimates have been showing that perhaps it's best to plan on $4,000...by the time it's over with anyway...
That's for a fully balanced job, includes a gently ported head expertly mated to the cam, new electronics as Bill recommends...and perhaps a re-chip.

Riblett: "I am more concerned with the engine electronics than I am with the mechanical bits."
Click to expand...

Bill hit the nail on the head with his comment directed at what I also feel is a significant issue on the swap. Rather than go for the largest and most-est
just pay attention to the simple stuff...especially your e9's new electronics.

Fortunately locating and then overhauling an unknown M30B35 may just NOT be a part of my restoration activity this time around. It's my take that a very civilized ride with more power and far better road-manners including improved cold starts, high-altitude driving without a hitch and fast switchback turns (fun) without carburetor hesitation. Simply upgrading from dual carbs to Motronic FI on a ported head (smaller valves, sure) will yield a very good result in many ways...especially with the right cam and exhaust. I'm theorizing that for the e9 upping the standard 170 hp (US) unit to perhaps 235 hp. is plenty. (see tables below)

800px-CS-Front-1.jpg


Bertocchi: "Anything else, I feel, is a crap shoot."
Click to expand...
Why gamble? I say, If one is going to source a new powerplant ... Why not go Euro Twin Cam? (at least on my e24 CSi, that is and up the hp slightly from 185 to 280 if I use a euro M88/3 powerplant) Taking care to address the potential DMV and CA smog issues via a testing waiver.

I have also discovered that one of the surprising advantages of building an e9 from the ground up (and that means) beginning with a no-issue, fully reworked and vastly improved, cross braced and otherwise stregthened (and because of the Lizard skin and sound insulation layered coatings, powder-coated chassis members and upgraded hydrailics) should result in a car that can actually run with the best, be washed with a hose...and provide years of trouble free service...

For my drive train of choice, I have been considering many different options, yet in the final analysis the offerings all lead me to the same, cost effective conclution...and that is to take my perfectly geared and expertly engineered tried-and-true (known) 3.2 Motronic (first generation) M30B32engine, transmission (260/5) driveshaft and differential out of my e24 and put it promptly into the new e9 Coupe.

Rebuilt now or later, the e9 re-wiring for the M30 will consume many, many hours of careful work, but i am convinced it will be worth every second..

And IF I am going to have an engine rebuilt by someone (and not do it myself) and it's to be for the 'go-fast' car (the e24) I likely will step up the pace a bit and install a fresh twin-cam M88/3 motor/ancilliaries, upgrade to the 265/5-6 Getrag and finally (snow country here) finally have a full LSD.

Not ALL that much more horsepower, but the sound and responsivness of that engine (being what it is) is perfect for freshening up the Sixer's drivability and my experience of doing so again... The euro bumpers and new seats might go a long way toward making her a bit different looking too...at least for the next few thousand miles anyway.

So that's where i am at and likely going to put the $4k there as in my case it just seems to make more sense...to each his own...see you on the road!

Ran

Picture4-4.png


Applications:
1973-1976 E12 525
1976-1981 E12 525

M30B25

Applications:
1981-1987 E28 525i

M30B28

2.8 L (2788 cc) Applications:
1979-1987 E24 628CSi
04/1981-12/1987 E28 528i
M30B30

Introduced in 1986 with the E32, the 3.0 L (2986 cc) M30B30 produced 185 hp. The engine continued in production until 1994.
Applications:
1986-1994 E32 7-Series
1988-1993 E34 5-Series
3.0 L (2986 cc) Applications:
1976-1979 E24 630CS

M30B32

3.2 L (3210 cc) Applications:
1976-1984 E24 633CSi

M30B34

3.4 L
8.0:1 compression ratio
Applications:
1985-1988 E28 5-Series
1985-1987 E24 6-Series
1985-1987 E23 7-Series
3.4 L (3430 cc) Applications:
1983-1993 Europe
1985-1993 US
M30B35

3.4 liter (3430 cc) SOHC inline-6 cylinder
9.0:1 compression ratio
208 hp @ 5700 rpm
225 ft·lbf torque @ 4000 rpm
87 AKI / 91 RON octane fuel or better recommended
Applications:
1988-1989 E24 635CSi
1988-1993 E34 535i
1988-1992 E32 735i
3.5 L M90 (3453 cc) Applications:
1978-1983 E24 635CSi
1980-1981 E12 M535i
 
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M6 engine

Does anyone know of an M6 transplant? I apologize in advance if I am not knowledgeable on all the M & E numbers. :mrgreen:
 
89 535

I know of a great condition 89 535i 5sp with less than 80000 original miles that is available for $4500 is anyone is interested.
 
Sooner said:
I know of a great condition 89 535i 5sp with less than 80000 original miles that is available for $4500 is anyone is interested.
Click to expand...

Where?
HMM, that's almost too nice to hack up!


Bill Riblett said:
Based on my 15 years' experience with my 635, I am more concerned with the engine electronics than I am with the mechanical bits. I would strongly urge replacing all the sensors and relays, as well as the Motronic control unit. I've had the following fail: main engine relay, fuel pump relay, control unit, and position sensor (twice).
Click to expand...
Good point Bill, I hadn't really thought of that. I remember having injector leakdown issues and crank sensor issues w/ my 91 535 after 100k. Expensive and less than fun.

@ Ran, thanks for the engine chart, that's helpful too. And yes, I agree that a rebuilt B35 that originally had 200k is probably better than an original 90k mile B35 becasue of the unknowns. Throw the $$$ at the proper rebuild and you absolutely know you'll get another 100k plus out of the engine. The bottom ends in these things really do run forever.

Thanks everyone for their valuable feedback. As always, it was just enough factual information to pretty much scare my depleted checkbook back into the desk drawer for now!
In all seriousness, this is sort of a due diligence exercise for me, so this is really helpful.
 
Thanks everyone for their valuable feedback. As always, it was just enough factual information to pretty much scare my depleted checkbook back into the desk drawer for now!
In all seriousness, this is sort of a due diligence exercise for me, so this is really helpful.
__________________
Click to expand...

...and that is so true..(laughing so hard it hurts!) and interestingly also fodder for many hair raising stories yet to unfold on these sacred pages!

PS...U kindly welcome, acat!
 
To answer Bertocchi's query, there have been a few M5/M6 (S38) transplants done for coupes; however, aside from the motor I have not seen a complete listing of all the parts/ labor required for this swap. I have to admit to being very, very tempted by this conversion. I have the 3.5L, 1.3 motronic FI conversion now and while I am really pleased with the enormous bump in performance/reliability over stock I have to admit that I lust after having a true sleeper. Yes, I know putting on a turbo would probably net more gains than a stock s38, but what did someone say about turbos; 'power too late,' and there is just something about that s38 in the e9 that looks so right. Cost is obviously the big concern for this conversion, because while I am seeing plenty of M cars of the right vintage for amounts that are reasonable, the fact remains that a likely rebuild for the motor will run close to $10K from all the research I've done. So, you add the cost of the motor, rebuild, and labor, you are looking at $20K easy.

That being said, does anyone know if the s38 from a 1990s M5 has ever been dropped in a coupe as this would be an out of the box rating of 310HP (s38b35) or 340HP (s38b36) over the 1980s s38's rated at about 256HP?

-Walt
 
Mario L. said:
Jranmann . . . just where did you find that picture of the CS Coupe we did at VSR?? never knew I let that one out of the box!
Mario L.
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The very same way that led to my decision to recommend your services to a coupe of your newer clients...research and dilligent attention to detail...something you and I share, obviously?
:mrgreen:

Would you like me to send you the rest of the roll?

Cheers,

Ran

PS how's the new staff working out for you?
 
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Ran,

Maybe you've answered this but I can't find it. Can you confirm the HP and torque on a 3.5 FI motor out of a euro 1985 M535i? Is it 218 or 194? I've heard different viewpoints on what years the euro motors had higher compression than the US car's motors.

Thanks,
Vince
 
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