Engine & transmission combination for responsiveness

[Buzz204]

I'm a newbie so please pardon any obvious gaffes!
I had a new 72 3.0CS (which rusted badly) and in 91 a new M5. The CS as you all know here was a gorgeous marvel and only the rusting prevented me from keeping it - wish I had! The M5 was a different thing altogether, after 3 911's it was just staggering. It just wanted to leap to the redline - it was so responsive! I know others have put an M5 engine into an E9 but at my age that is sheer fantasy. But what I would really like would be an E9 with a more responsive engine (not necessarily twin cam) and a matching transmission (probably 5 speed?) with short gears for fun but an overdrive top for cruising. Ease of service and reliability would be significant factors. Want to wind up with a tidy driver not a matching numbers show queen
I do follow these discussions but find most to require substantial insider knowledge. Is there a reference that you can direct me to or is there sufficient patience out there to help me get started?

 

[rsporsche]

hey ... you have a few questions in your post. i will try to tackle them in ease of answer to provide a little clarity.

first advice - do NOT buy rust on a coupe ... and keep the car dry.

tranny - there are only a few available
- getrag 265/6 and overdrive 5 speed ... the first 4 gears are the same as the 4 speed
- getrag 265/5 close ratio (dogleg) ... 5th gear is the same as 4th gear on the 4 speed box ... the other gears are closer together which makes for quicker acceleration ... but no 5th gear overdrive. these boxes have become very expensive and hard to find. primarily in euro 635csi. these are usually used with a 3.25:1 or 3.46:1 diff.

if you want to change the acceleration with the overdrive box - change the gearing in the diff. standard diffs are either 3.46:1 or 3.64:1 ... you can replace gears such as 3.91 or 4.11 which will bring the gears closer together. 3000 rpm in each is a different speed - 3.46 (79mph), 3.64 (75 mph) and 3.91 (70 mph)

engines - other than stock, there are 4 basic options worth considering.
- euro m30 b34 (10:1 compression) ... do NOT buy a US b34
- euro m90 (hard to find - primarily in the euro 635csi and came with the dogleg box)
- m30 b35 (very available from many models in the late 80's)
- s38 (from the e28 or e34 M5 - this has become an expensive engine to buy + build) ... great performance

the other improvement to give you a more modern coupe is to upgrade the suspension - a few people who drove the RAAB Classic coupe in Germany raved about the KW coilover system on the coupe ... really giving the coupe the most modern ride.

with the first 3 engines, you can use motronic injection, but something like megasquirt with a better cam and exhaust will provide 240+ hp. you can also build a stouter engine with these choices and get very impressive performance. these engines can have good reliability if setup properly. i don't know anybody in Canada, but a visit to Mario Langsten at VSR in NH can get you a very interesting / well performed e9 ... or sending the car to our friend @sfdon will get you similar results ... just a lot longer way away. both have reasonable backlogs so you can't be in a rush.

 

[Patton]

Buzz204, I have the car you want.

See the "build" pages in this forum area.

"At the end of the day..."
Well, it is a 50 year old car with shakes and rattles and wind noise But, the old coupe does look good.. Kinda like a far away view of Dolly Pardon in a Dallas Cowboy cheerleader outfit.

A Toyota Camry has more horsepower than the dyno-tuned M88 engine. It drives better, too.
Enjoy the hobby, but 50 years of automotive progress makes the driving experience...well, quaint.

RP

 

[rsporsche]

but does that Camry have the same thrilling sound or feel? in a word NO. we don't even need to talk about the looks ...

 

[Ohmess]

There are a number of forum members who have gone to the M30b35 engine mated to a 265/6. This engine is readily available, the swap is straight forward, and the engine provides lots of low end torque, which is what gets you down the road. Moreover, BMW sold thousands of these in the US so parts, and most importantly, trained mechanics who can work on these are relatively easy to find.

 

[Buzz204]

hey ... you have a few questions in your post. i will try to tackle them in ease of answer to provide a little clarity.

first advice - do NOT buy rust on a coupe ... and keep the car dry.

tranny - there are only a few available
- getrag 265/6 and overdrive 5 speed ... the first 4 gears are the same as the 4 speed
- getrag 265/5 close ratio (dogleg) ... 5th gear is the same as 4th gear on the 4 speed box ... the other gears are closer together which makes for quicker acceleration ... but no 5th gear overdrive. these boxes have become very expensive and hard to find. primarily in euro 635csi. these are usually used with a 3.25:1 or 3.46:1 diff.

if you want to change the acceleration with the overdrive box - change the gearing in the diff. standard diffs are either 3.46:1 or 3.64:1 ... you can replace gears such as 3.91 or 4.11 which will bring the gears closer together. 3000 rpm in each is a different speed - 3.46 (79mph), 3.64 (75 mph) and 3.91 (70 mph)

engines - other than stock, there are 4 basic options worth considering.
- euro m30 b34 (10:1 compression) ... do NOT buy a US b34
- euro m90 (hard to find - primarily in the euro 635csi and came with the dogleg box)
- m30 b35 (very available from many models in the late 80's)
- s38 (from the e28 or e34 M5 - this has become an expensive engine to buy + build) ... great performance

the other improvement to give you a more modern coupe is to upgrade the suspension - a few people who drove the RAAB Classic coupe in Germany raved about the KW coilover system on the coupe ... really giving the coupe the most modern ride.

with the first 3 engines, you can use motronic injection, but something like megasquirt with a better cam and exhaust will provide 240+ hp. you can also build a stouter engine with these choices and get very impressive performance. these engines can have good reliability if setup properly. i don't know anybody in Canada, but a visit to Mario Langsten at VSR in NH can get you a very interesting / well performed e9 ... or sending the car to our friend @sfdon will get you similar results ... just a lot longer way away. both have reasonable backlogs so you can't be in a rush.

Thank you RS, great start!

 

[Buzz204]

There are a number of forum members who have gone to the M30b35 engine mated to a 265/6. This engine is readily available, the swap is straight forward, and the engine provides lots of low end torque, which is what gets you down the road. Moreover, BMW sold thousands of these in the US so parts, and most importantly, trained mechanics who can work on these are relatively easy to find.

Thank you Chris.

 

[daicos35]

My vote, as above , m30b35, getrag 265/6 (od box), with 3.46 or 3.64 final drive. From there, raab suspension. I also think a lsd is important as all other components to improve drivability fun.

 

[teahead]

3.64 rear would be ideal if you had an OD trans.

 

[daicos35]

I agree Rob.. A little punchier, but there is some debate on this point,, first is slightly short, but after that, it is all gravy...