M30 Carb'd performance mods

7173bmw

7173bmw

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Does such a book or reference guide exist? Anyone except Korman and LaJolla work on heads, cranks, blocks on the East Coast?

I'm working on a 3.0L for my '73 and would like to go Bat Mobile, with a six pack of sidedraft webers, 1 5/8 exhaust manifolds, hot cam, worked head, grp 4 fenders.

Can I achieve a nice/noticable bump in performance if I: port and polish the head, increase valves, change cam to work with the weber conversion?

Do I need a new camshaft, lifters, intake & exhaust valves? I realize you can go full tilt with something like this. I just want a little more while keeping more in my pocket!

Any recommendations?

Thanks!

Nick
 
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How much are you looking for? The cheapest horsepower is to drop in a later M30B35. This will gain you bigger valves, a better-flowing head, a bump to 9:1 CR, and a ~0.4L bump in displacement. You can also build these engines out to ~3.7L without block work if you get the correct combination of bits. (M90 block, E3 3.3L 88mm crank, M30B35 heads, custom pistons) The most you can bore out is to ~94mm, otherwise you end up with head gasket sealing issues between pistons.

Most of the Gr5 cars used a precursor to the M88/S38, meaning they are DOHC. You can go that route and use a M88 or S38, but it is a bit more work and more expensive. You can end up with ~350 rwhp NA that way, though.
 
Thanks x-atlas!

I was hoping to work with what I have. Can I bolt on the M30B35 head then add the Webers? Does the M30B35 need upgraded cam?

Where should I look to figure out exactly what motor Im working with? I once started putting together parts to upgrade a 2.7L motor I purchased for my 911 project to find that I bought a 3.0L motor instead. The previous owner had no idea!

Thanks!
 
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7173bmw said:
Thanks x-atlas!

I was hoping to work with what I have. Can I bolt on the M30B35 head then add the Webers? Does the M30B35 need upgraded cam?

Where should I look to figure out exactly what motor Im working with? I once started putting together parts to upgrade a 2.7L motor I purchased for my 911 project to find that I bought a 3.0L motor instead. The previous owner had no idea!

Thanks!
Click to expand...

It will cost more to change what you have. Used M30B35 long blocks go for <500$.

You can add a B35 head, but you will have to mix/match some parts from the existing head, like the upper timing cover, and you will have to add a dizzy drive cam conversion nut to the B35 cam end. You will lose some CR in the process, though, as older M30s have a smaller clearance volume compared to the B35. It should drop you about a point to 7:1, which will cut power a good bit. Of course, that's why the turbo guys love it, but as a NA mod it doesn't help.

The triple Webers will work on any M30 but you will have problems clearing the stock brake booster. You will need to either convert to a hydro system from an E28/E24 or find a 2002tii brake booster. You will also need to convert to an electric low pressure fuel pump, as the stock fuel pump is mechanical and bolted to the head.

In terms of cam, the stock 3.0CS cam was a 272. The M30B35 is a 260. The "optimal" is a 284, which provides the most power with the least compromises. The hottest useful cam I have heard of is a 300, but that is pretty lumpy based on accounts.

You can check the block PN by looking on the block. The exact location of the PN escapes me at the moment, but I think it is on the exhaust side beneath the front exhaust manifold. You can also look at the VIN stamp on the starter ring; if it matches the car, then it is likely the original displacement. (2.8 or 3.0)
 
I would suggest as XAtlas says to verify what engine you have and if original. If that isn't the case, then anything is possible given time, abilities, and money.

The early tuners, Alpina, etc can be researched as a guide to what level of performance you desire as long as you understand the trade-offs of a street vs. leaning towards a racer type tune. They were generally restricted by class rules of the day. Weight plays a very important part, so there's that route as well.

But, generally high compression, stroked, flowed, cammed, headers can get you in the 220-240 hp with obviously the larger displacement being the easiest route.

Carbed cars generally had a slightly wider lobe center on the cam vs. FI. Even if you have the original block and that's a factor, stroking and high compression pistons ( Euro or custom) is the easiest path. But, the original M30 heads have flow limitations at some point in the horsepower equation. So anything that increases flow is the next step in my mind.

The M88 dual cam's benefit was the increase in flow from dual valves and better ports since the engines are canted and there's a flow restriction right there to overcome. Racers then and now still twist the block straight, dry sump, etc. in order to get the best or most direct intake path.

Of course, there's always forced induction which many have done.

I suggest you talk to VSR or VAC Motorsports in your area to get an idea or target. It also never hurts to find the local BMW club and see what those guys do local to you since the M30 has been around a long time. Chnaces are there's someone near you that's done it before.
 
VSR in Bow, NH

7173bmw said:
Does such a book or reference guide exist? Anyone except Korman and LaJolla work on heads, cranks, blocks on the East Coast?

I'm working on a 3.0L for my '73 and would like to go Bat Mobile, with a six pack of sidedraft webers, 1 5/8 exhaust manifolds, hot cam, worked head, grp 4 fenders.

Can I achieve a nice/noticable bump in performance if I: port and polish the head, increase valves, change cam to work with the weber conversion?

Do I need a new camshaft, lifters, intake & exhaust valves? I realize you can go full tilt with something like this. I just want a little more while keeping more in my pocket!

Any recommendations?

Thanks!

Nick
Click to expand...

I would definitely talk with Mario Langsten at Vintage Sports and Racing/Restoration (VSR) in Bow, NH. Mario is a really good guy, extremely knowledgeable about BMW engines, easy to work with, and not as remote as NH might sound, as he travels all over the region, delivering and picking up customer's cars.

--Steve
 
Thanks guys...here's a little broader picture:

Motors are original to all 3 cars(2 '73 3.0CS, 1 '71 2800CS)

One car is going to my wife, one I thought I would make a street legal Bat Mobile for myself, and the third is almost down to the shell(been stripping down to powdercoat suspension parts for 1st car and keep spare parts and bits) and is going to a buddy in trade for some metal work he's doing for me.

So what model cars should I be looking for for a M30B35? It does seem more cost effective to swap the power plant and build from there.

Thanks for all the good info!
 
You're looking for a 3.5 motor of two varieties:

1. 88-91 5, 6, or 7 series. 635, 735s, etc. Make certain it's a 3.5 as some seller's don't know the difference. Early 88s have dual bosses for the motor mount. If later, an adapter plate is needed.

2. Euro or dirty motor 3.5 from 80 or 81. Usually a 635. This still has the distributer.

If you find an automatic donor, could be a plus as there's a little less wear. Lots of info on these types of swaps out there. First Fives is a good website for technical info on bits that need to be changed.
 
Thanks guys!

What kind of hp could I expect with one of these motors?

Could I get my current 3.0 to 240-260hp?

1. 88-91 5, 6, or 7 series. 635, 735s, etc. Make certain it's a 3.5 as some seller's don't know the difference. Early 88s have dual bosses for the motor mount. If later, an adapter plate is needed.(what kind of pricing am I looking at?)

2. Euro or dirty motor 3.5 from 80 or 81. Usually a 635. This still has the distributer.(what's this mean...sorry, kind of lost)

If you find an automatic donor, could be a plus as there's a little less wear. Lots of info on these types of swaps out there. First Fives is a good website for technical info on bits that need to be changed.

Thanks guys!
 
AWESOME!!!! PERFECT!

Called Mario...what an awesome resource! Thank you again!

Thanks!
 
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230HP 3.0 liter engine

7173bmw said:
Thanks guys!

What kind of hp could I expect with one of these motors?

Could I get my current 3.0 to 240-260hp?
Click to expand...
I have a 3.0 built to stage 2 specs by Korman back in 1980. It has 9.5 pistons, 300 degree (regrind) cam, reworked cylinder head, reworked rocker arms, header (was Supersprint, now Stahl 13/8"), triple Weber 40DCOEs, "euro" "008" distributor and probably more I have forgotten. When new it put out 230HP at 7200RPM on Korman's dyno.
 
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