333i

[Jean]

then whats the use of going m30? a healthy m50/slight modded m20 easily makes that.?

Well, it's not all about peak hp... but area under the curve or torque delivery at low revs.

Personally I went with the latest revision from an e32 as it's rated at 208hp/225ft/lb stock (as a bonus it has less vacuum lines, and looks cleaner imho) :)

But I believe Andrew went with b34 as it's the closest thing to the 3.3L Alpina used? That's my understanding.

[CorvallisBMW]

^That's only in the Motronic 1.1, '3.3' liter version (it's actually 3430cc). They didn't make much more power than an m20 b/c they were a much older design (First used in '84, about 13 years before the m20b25 was deployed), with a first-gen engine management system. They do however make considerably more torque, 213 ft-lbs. M30B35 engines make about 210hp/225ft-lbs and run motronic 1.3 w/ a 9.0:1 CR, a much bigger power gain with considerably less complicated wiring and plumbing.

Andrew, OEM motor arms are a fully-boxed design which is the reason they could get away with holes.

Also a boot hinge holds up, what, 25lbs? And control arms (not wishbones, totally different type of suspension) are cast iron, a very different material. If you're that worried over the 8oz of weight you saved by cutting holes in them, why not move the 30lb battery to the trunk?

I hope they work out great, I'm not trying to shit talk or put you down. I'm just worried that after 1000 miles or so of engine vibration you're going to get some massive stress fractures. Thinner metal is susceptible to cracks and fractures when exposed to vibration, and then add the weight of the motor on top of that, and the fact that they were probably not stress-relieved after welding..... Just be careful, ok? Keep an eye on them.

[xwill112x]

I believe e28 b34s are 3.4 L with 8.0:1 compression ratio = 185 hp?

then whats the use of going m30? a healthy m50/slight modded m20 easily makes that.?

[Jean]

I believe e28 b34s are 3.4 L with 8.0:1 compression ratio = 185 hp?

[JasonC]

What is the HP and torq #'s this motor puts out? Also what gears are you running?

[Iain]

I don't mean to get into a shitfight, but Andrew there are some fairly rudimentary differences in the parts you mention which have holes pressed in them from the factory and the motor arms.

[xwill112x]

Jesus, don't flatter yourself too much. Engineer calculations WERE done on these, I'm not stupid enough to create a part as crucial as engine mounts off the fly going by solely looks. Although a picture is worth a thousand words, don't judge a book by it's cover. They have incredible structural integrity rest assured. The steel is thicker than you think, and have you ever seen a BMW boot hinge? wishbones? Drilling holes is for weight reduction. Although it seems silly to reduce weight in a none track car, it gives the mount arms a much more OEM look. Drilling those holes play minimal role in structural integrity. These mount arms can withstand an incredible amount of force.

better knock on wood after that one..

[Japandrew73]

As an engineer I am skeptical. Especially with a bazillion holes cut in them. Now I can only go by the photos, but a picture is worth a thousand words. And having helped build a world-championship-winning race car in college, I know a thing or two about building parts. Those are much thinner than stock m20 mount arms, and have to hold up much more motor and contend with more power. Ive used m30 mounts from Funk and Otis, both sets were considerably heftier than these.

Were there any engr calculations done on these? FEA, or even basic static forces calcs?

Jesus, don't flatter yourself too much. Engineer calculations WERE done on these, I'm not stupid enough to create a part as crucial as engine mounts off the fly going by solely looks. Although a picture is worth a thousand words, don't judge a book by it's cover. They have incredible structural integrity rest assured. The steel is thicker than you think, and have you ever seen a BMW boot hinge? wishbones? Drilling holes is for weight reduction. Although it seems silly to reduce weight in a none track car, it gives the mount arms a much more OEM look. Drilling those holes play minimal role in structural integrity. These mount arms can withstand an incredible amount of force.

[CorvallisBMW]

You must of missed this part

"They are made of a very sturdy gauge of steel (can't remember exact gauge) and notice the how on every bend there is a tower for more support. They aren't exactly what most people are used to seeing, but they do their job perfectly."

As an engineer I am skeptical. Especially with a bazillion holes cut in them. Now I can only go by the photos, but a picture is worth a thousand words. And having helped build a world-championship-winning race car in college, I know a thing or two about building parts. Those are much thinner than stock m20 mount arms, and have to hold up much more motor and contend with more power. Ive used m30 mounts from Funk and Otis, both sets were considerably heftier than these.

Were there any engr calculations done on these? FEA, or even basic static forces calcs?

[daniel]

congratulations on almost finishing. i don't know enough about mechanical things to criticize your choices, so i won't. i'm simply blown away at the scope of this project, including the rest of your car. it makes me really happy to see that you did it. i hope i can see your car in person some day.

[VicSkimmr]

I'm sorry, am I reading this right? You're worried about the "period correct look" of your engine mount arms?

...this is surprising to you?

The car looks tits btw, great job.

[10Toes]

You must of missed this part

"They are made of a very sturdy gauge of steel (can't remember exact gauge) and notice the how on every bend there is a tower for more support. They aren't exactly what most people are used to seeing, but they do their job perfectly."

[CorvallisBMW]

They have a very period correct look to them I'd say.

I'm sorry, am I reading this right? You're worried about the "period correct look" of your engine mount arms? Looks don't count for shit, it's the strength of them that matters. You can't see them anyways, and they'll look pretty un-period correct if the engine falls out the bottom of the car with twisted, broken arms.

Not saying it will, but BMW didn't become the car maker it is today buy building flimsy-yet-pretty cars. Think about that...

[beenjamin]

Your bay is beautiful, you could hide a person in there

[Japandrew73]

Those mounts look, um, thin

How sure are you about their strength?

They look thin yes, but are very structurally sound. The mounts started with cardboard and were designed based around Hartge's H35 mounts. They have a very period correct look to them I'd say. They are made of a very sturdy gauge of steel (can't remember exact gauge) and notice the how on every bend there is a tower for more support. They aren't exactly what most people are used to seeing, but they do their job perfectly.

Excuse me for either not recalling, or for it not being here, but are you running the G240?

Tranny is a Getrag 260