manifolds/megasquirt on inline sixes?

[todds]

Do all of the smaller sixes have the same manifold bolt patterns/flange dimensions? I'm going to start slowly assembling all the parts needed to attempt a megasquirt installation on my car. I've always been incredibly intrigued by the idea. The biggest problems are constructing a fuel rail and finding places for the sensors to go. I figure, as far as fuel goes, I can retain the stock pump and just install a small reservoir and high pressure pump up near the engine so that I won't need to worry about fuel lines all the way to the tank, similar to the way this guy did it:

http://home.comcast.net/~qcrispin/Megasquirt/Megasquirt.htm

It seems that it would be easier to rely on M-B's engineering in terms of the manifolding and fuel rail as opposed to re-inventing all of that with a carb'ed manifold. I suppose worst case the carbs could be used as throttle bodies and it could be all be fab'ed. I don't suppose there is any way of fitting modern injectors to the older FI manifolds? Is there a newer EFI manifold that would fit the older engines?

Then there's the question of those pesky heat flaps and the exhaust/intake interface.

"You can do it!" type advice is always preferred to "it's impossible" type advice. The plan would be to obtain a stock/junk manifold and parts such as not to disturb or destroy the original parts of the car. Heck, why bother converting to Webers? Perhaps this is all a pipe dream...

[Jengasan]

but why would you want to ?....or do you have carbs ??? (in which case I'd totally understand).

I have already looked into putting a megasquirt based system on my 280SE 3.5 and it's perfectly doable, probably a bit easier than your straight six, but don't let that put you off. As I've said on here before, we worked out that my whole car could be done (including wasted spark electronic ignition) for less than the cost of a new MAP sensor from MB for the current D-Jetronic system, albeit that I'd be 'doing' it rather than a shop.

I'm in the UK and have sourced suppliers for things like custom fuel rails, injectors, throttle bodies etc all at reasonable cost, not cheap, but reasonable. If you go with megasquirt you may as well go wasted spark ignition too and this is really cheap using a lot of recylced parts, again I know good sources of things like Hall effect sensors, trigger wheels, coild packs etc. but considering how much EFI there is in the States (I assume that's where you are) I'd bet you could get cheaper.

The only real brain ache I can think of is how to get a decent fuel map to start you off...old MBs aren't really the first choice of the EFI junkies.

Good luck

Jengasan

p.s. IF you could get a 4.5 V8 engine and fuel system cheap enough...it would be easier not to mention more powerful

[Mike D]

Keep us updated on your progress.

I am working on converting a M115 with twin Solex's. I am going to go with a single throttle body injector. I will be using a surge tank fed by an electric pump. Right now I am making a auxillary intake feed to convert the dual air feed into a single to eliminate the need for the extra linkage.

Throttle bodies are cheap and plentiful. I'm 80% complete with a M110 (carbed version) conversion on a 280C. I'm using the TBI unit from a 90's GM 2.5L mounted on a 4BBL to 2BBL adapter.

[todds]

That's really interesting Mike. TBI would most likely be much easier because I could retain the stock air cleaner and intake manifold. On my m180 I'd have to run two throttle bodies (one for each carb I chucked away) which would increase the cost, but its perfectly within the realm of megasquirt. I'm quite certain that even TBI would be a vast improvement over dual leaky/warped zeniths! I wonder if there is some factory GM? unit that would reasonably replace them..

Jengasen, there is a fascinating saga of two or more megasquirt conversions on M-B 4.5 V8's at this link:

http://www.benzworld.org/forums/vintage-mercedes-benz/1318045-replacing-bosch-jetronic-megasquirt-efi.html

Their results sound very encouraging, even with basic tuning and lacking things like TPS and O2 sensors they claim smoother and better running than their factory injection setups. I'm rather comitted to my old m180 for some masochistic reason. It doesn't use a drop of oil, either burning OR leaking, isn't all THAT horrifying gas mileage-wise being only 2.3L, and is in quite perfect shape despite 40+ years of age. I see no reason to swap to a big V8. My oil stays clear for longer than any car I've owned. Additionally, people have DONE the V8's before. I bet I'd have the first EFI m180 on the planet. The only thing that is letting my engine down right now is the fuel system. My goal is not power, but driveability and making the engine last longer due to nicer fuel delivery.

[JMURiz]

Originally Posted by Mike D

Keep us updated on your progress.

I am working on converting a M115 with twin Solex's. I am going to go with a single throttle body injector. I will be using a surge tank fed by an electric pump. Right now I am making a auxillary intake feed to convert the dual air feed into a single to eliminate the need for the extra linkage.

Throttle bodies are cheap and plentiful. I'm 80% complete with a M110 (carbed version) conversion on a 280C. I'm using the TBI unit from a 90's GM 2.5L mounted on a 4BBL to 2BBL adapter.

Does that TBI system for the carbed M110 get enough cfm with a 2bbl TB setup? If so, let me know the details when finished too, that'd be a nice way to get easy startups etc on my carbed M110!

[Mike D]

You can use any throttle body you want. You can use one from a GM 7L (350 CI) or Ford 5L (302 CI) for airflow. The Megasquirt will adjust the fuel to compensate.

I'm using the 2.5L for two reasons. A: I prefer to lengthen the flow time for the injectors and B: I already have it.

Make sure you have a TBI with a "stepper" motor on it if you are using A/C. You can use one without it but as your A/C cycles on and off it tends to freak the ECU out. Although actually, here in Tucson, the A/C compressor never cycles off.

[todds]

I was thinking more in terms of physical fit on the manifold rather than if it would work functionally. Do you happen to know if the base mounting is the same as the zenith/weber DGV pattern?

[Mike D]

I haven't found one which just bolts on hence my statement of auxillary intake feed (a flange to fit each mounting, connected by a tube to a central mounting flange for the TBI).

Stock air filter? Hah! Ain't gonna happen.

[todds]

Yeah, I s'pose you're right. The stock 6-cyl air cleaner is such a cool byzantine labyrinth of overengineered chambers and tubes though. It seems like such a shame to eliminate it. I think its design must be left over from the oil bath days.

[wbain5280]

I've got the intake and exhaust manifolds from a 250SE M129 and they fit on my M180 for the '65 220S. There are no injector bungs so I'll have to get some holders welded on and drill the holes. I plan to put a Megasquirt system on my 220S in the near future. I'm also taking an engine class and I have to get my M180 down there for disassembly and refurbishment.

[Mike D]

I thought of doing something similiar to my M110. I have a spare intake and I was going to have the runners drilled and bungs installed. Unfortunately, by the time I figured in all the machine work, parts costs, fuel pressure issues, manufacturing the fuel rails and compensator rig AND the fact I still needed to install a throttle body kinda led me over to just converting to the TBI. I'm just lazy and cheap I guess.

[todds]

Interesting that the 250SE M129 manifolds fit... Would an M130 manifold fit as well?

[cth350]

With the exception of the M189 (3.0l motor), all those 50s & 60s mercedes straight 6s have interchangable manifolds.

Aside from the 3 or 4 varient MFI manifolds for the 220se, 250se and 280se (M127, M129 and M130) motors, there is also the M114E (250E and 250CE) manifold and the single carb manifold for the unimogs and transporter (buses).

However you won't find many of those last two in the US.

I know of at least one M100 (6.9) motor that had its CIS injector ports (in the head) widened to accept much larger EFI injectors. The same trick should be doable for the various MFI straight 6s. All that was required (hah!) was a jig to aim a milling machine down the throat of the original bore and widen it (2 or 3 times). -CTH