MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - Moss EFI Setup

Well guys, what do you think of Moss's new toy?
David

The most amazing thing is that they got it
certified under California emissions laws.

I don't understand how it can work well without
an oxygen sensor, however. Maybe someone more
tech minded can explain this? Looks really neat,
but pricewise the single SU also sold by Moss and
VB seems to be a better deal.

The late Bs (at least mine) have trouble keeping
a relatively constant idle speed
under large electrical
load variations due to the twin fans and headlights.
I think the EFI would help with this.
Ronald

Where can I find more information about the Moss EFI Setup?
John Perkins

It is in the current edition of British Motoring magazine which is a free publication from Moss motors. They have not updated the magazine site with the new edition and the injection system is not in the online catalog yet either it is so new.
http://www.britishmotoring.net/
http://www.mossmotors.com/

Carl W French

With no O2 sensor it's running in "open loop" mode -- it doesn't look at the exhaust to see if it needs to tweak the mixture. Not ideal, but on the other hand no worse than what a carburretor does. I don't know about California, but North Carolina is fairly generous in their requirements for pre-1980 vehicles, so I suppose that's how they got the EFI system to qualify. As I recall, the NC requirement for 1978 is not more than 3.5% CO, 350 ppm HC.

They said in the blurb that it uses a custom ECU. I wonder if it has the O2 sensor circuitry in it, and could an O2 sensor be added if the buyer so desires....
Rob Edwards

They could have spent a lot of time on a dyno and dialed in a good "compromise" for most motors, and burned the chip at that setting. No, not as good as oxygen sensors, and constantly adjusting systems, but it'll suffice.

FWIW
Justin
Justin

In my mind, the biggest advantage to EFI and more specifically, port injection, is that you can design a more favorable inlet manifold. This means you can tune the inlet to the operating range (or ranges) best suited to driving performance without compromising mixture composition, as could happen when using carburetors.

I am quite interested in what Moss may have to offer, but I think they may be missing the boat by not offering a good manifold package (taking the above criteria in mind) along with the rest of the hardware.

Sean
Sean Brown

How much harder or more expensive would it have been to include an O2 sensor and the bunge to have welded in by a muffler shop? Seems kinda half-assed IMHO. I mean if you're going to spend 1400 what's another 50 or so for an O2 sensor and 50 to have the bunge welded in?
Mike MaGee

Mike - Taking a guess at it, I'd say it would be hugely more difficult. Not because of the cost (or price - an altogether different thing!) of the oxygen sensor, but the effort required to engineer this feedback device. OEM's would put a half-dozen engineers, a platoon of technicians and development engineers and a test facility on it - and that's doing it on the cheap!

I haven't seen my Moss Motoring yet, but from what I gather here, it's a throttle body injection system taking the place of the single carb. A fairly primitive early eighties sort of FI, a "set it and forget it" sort of system. All moss had to do was develop one calibration.

The oxygen sensor is a constant feedback system requiring the software and the systems work to read and react in real time. A wholly different kettle of fish from the "Mark I" system now becoming available. The oxygen-reading feedback ("Lambda") system is a really elegant solution to provide low emissions and improved performance but it probably requires more development resources than what Moss has available at the moment. Give it some time!
John Z

I agree with Sean, the major advantage of an EFI is when you can design a better 'dry' intake manifold. Or for use with a turbo/supercharger. There is little to gain by adding the Oxygen sensor. The oxygen sensor is in play for 'lean' mixture (cruise) only. To do port injection it helps to have a different head as discussed in the previous thread.

The Oxygen sensor is not usefull for best power, only for cruising. Most EFI systems run open loop except for cruising/idling. The oxygen sensor gives better fuel economy, and provides the mixture needed for a '3-way Catalytic converter' for low emissions. If you stomp on the gas the system goes open loop.

The later MG's do not have a 3-way catalytic convertor. Later MG's (with converters) are actually run richer for best emissions (5.5% CO) than earlier SU carb MG's (3.5% CO). The rich mixture provides an 'after burn' for the exhaust. An EFI system running closed loop with an Oxygen sensor, runs lean (near 0% CO). I'm not sure how well the MG head runs this lean under normal driving conditions.
werner haussmann

The real problem here is the siamesed ports of the head. True, they could have run a separate injector for each port which would have meant two injectors instead of one and that wouldn't have been tremendously difficult, but then the timing of injector-on time becomes critical to avoid leaning out one cylinder in each pair. So a dry manifold, though not impossible is made considerably more difficult. This also goes to the heart of the problem with a feedback loop. If you can't control the cylinders individually or at least balance them out evenly under all conditions then emissions control and use of catalysts is a lot less feasible, and feedback without fine control is of questionable benefit. My opinion is that the fundamental design compromises of the stock head make the Moss design probably the best compromise for fuel injection for this engine and some advantage over a single carb should exist, but bear in mind that the injector is a binary device. It is either on or off. So unless it is feeding a single cylinder so that you know where all the fuel is going, just exactly when it is on and when it is off becomes an important issue. By feeding four cylinders down two runners from one point the problem is lessened somewhat but isn't eliminated entirely. Applying current technology to the engine would mean a crossflow head, port injection, an IR/plenum intake, and feeback loop, but that runs into some money, and it's probably about the same cost to fit a late Rover V8 with EFI. For performance with the stock engine the dual SU is still a pretty good approach.

Jim
Jim Blackwood

Jim,

I have reason to believe that it's not as hard as you may think! There is a local talent in my neck of the woods who already has a running, proto-type 1275cc A-series in a Sprite and their budget is much lower than anything Moss would admit to.

However, it could easily be that Moss does not employ the right mix of persons to come up with a good dry manifold or port injection system. That being the case, it may be too expensive a proposition for them to farm out the necessary engineering work regarding the development of those components. They do seem to have some "feel" for what the market demands, so I'm sure they have reasons of their own.

My post was mainly stated along the lines of what I would do, or more specifically, what would interest me. A replacement for the ZS using the stock one-piece inlet/exhaust manifold doesn't sound like much of an improvement to me. I guess there may be less maintenance and possibly some derivability improvement. But if you're going to the trouble anyway, why not scrap the junk components and start with something from a clean sheet of paper? The need for later cars to pass physical smog check is the only reason I can see. It may also be that Moss did not want the hassle of trying to make a (what I feel would be) better system attain a CARB exemption (again costing money).

Sean
Sean Brown

It there used to be a guy from Moss who posted on this board. Where is he now to answer our questions about this setup? It seems to me that they took the "easiest way out" in developing this setup and used as many off-the-shelf parts as they could. Since it has been in development for 18 months, why didn't Moss ask their customers what they wanted to see in this system? They'll sell far fewer of these than if they went multi-port. Unless their whole intention was to build a system that worked well with their superchargers...
Jeff Schlemmer

Perhaps there is a long term perspective (longer than 18 mos) in what Moss is doing? By that I would wonder if the manifold that Sean suggests is part of yet another, updated package to be marketed later? Not every manufacturer comes out with a complete package from the beginning. And much of what happens in our area of autodom is pretty slow developing compared to the rest of industry.

Also, if I am not mistaken, I beleive that Moss has a share of TMW Induction Systems which is located down the street from them. To what extent they may be involved is an unanswered question. I am not certain of the level of expertise and engineering genius there, but it would make sense to utilize whatever they have that would be relevent.

If anyone wanted to check in with Craig Cody, our contact at Moss, his email is codyc@mossmotors.com Might as well get info from a source as to speculate.
Bob Muenchausen

" But if you're going to the trouble anyway, why not scrap the junk components and start with something from a clean sheet of paper?"

Cost. Quoth the article:
"We didn't want to design a unique intake manifold because it would make the cost of the system prohibitive." -- Mark Luis, Product Development Manager
Rob Edwards

Bob,
You make a good point -- once there is the basic setup, you can later offer upgrades to existing systems and upsells to new buyers...
Rob Edwards

A couple of years ago TWM was showing a FI setup in their advertising which looked like it would fit on a standard B manifold and basically said that such a system was "coming soon". I called to inquire and at the time was told that it was at least 6 months away from market and that it would probably sell for about $2,200., IIRC. The pictures subsequently disappeared from their ads and the projected cost squelched my interest so I never followed up and don't know if development was ever completed.
Marvin Deupree

Gentlemen:

If you have any questions, or if you see a thread that could use some feedback please let me know. I wander around the boards, but there is no way of being everywhere at the same time. I monitor mgs@autox.team.net as that was the first board I joined, but that is about it for continual monitoring.

To answer a few of the questions. The EFI was designed specifically to allow 1975-80 MGBs in highly regulated states to stay on the road legally, with an easy to install bolt on conversion. There are a pot load of cars which have to pass visual and pipe testing and in many cases the HIF44 conversion will not cut it. Justin hit the nail on the head, the system has to be simple and effective.

TWM and Moss have had no financial ties for a long time but they are just down the street and neat guys to play with.

Sean as usual is right on the money. The throttle body system is most effective if you are trying to make a direct bolt on replacement for an existing carb. The market for these units is mainly for those who are more interested in drivability than performance. I've been lobbying to have a single 4 bolt manifold made up which will accept either the HIF44 SU or the EFI unit, which will allow those with non-smog cars to install a simpler induction set up similar to the type available for the A series.
At the moment developing a high performance Fuel Injection system is beyond the scope of our budget as Sean and Werner pointed out, direct injection with feedback is the real way to get power and efficiency. I'm personally hoping to play with this as time and other projects permit.

Kelvin.
KJ Dodd

Thanks Kelvin for clearing up some items.

I still feel a need to add a few notes. Fuel injection's advantage is not just the dry intake manifold, but also the superior ability of an injector and a higher pressure fuel pump to better atomize the fuel, (particularly with multiple injectors), coupled with the ability to compensate for tempature, (engine and atmosphere) and barometric (including altitude) variations, irregardless of it being a open or closed (O2 sensor) system. The result can be better performance and better fuel mileage, but the best for us is probably the better driveability. The O2 sensor and a closed loop system would be great, but it probably wouldn't be worth the additional cost to us. For most of us, these are hobby cars after all.

I don't have info on the system, so does it have an adjustable ECU? A lot of tweaking could go on here... and think of the possibilities of injection and supercharging!
DLD Densmore

There used to be a home web page of a guy who put a older volvo tbi injection system on an MG. He was not able to do a separate port injection system because of the siamese ports. After much messing and fussing he got the system running very well. He reported the system put out about the same horsepower as the stock dual SU's. No intake tube tuning was effective because of the siamese intake ports. He wasn't worried about smog requirements and felt the exercise was an interesting one, but in the end, not worth repeating.
More modernly, if you could get a single carb late model engine to put out hp equivalent to the pre smog models AND consistently meet smog test requirements then that modification could be worthwhile. I've often thought that the tbi system from a mid '80's four cylinder Ford Tempo might not be that hard to adapt. The parts are readily available at any junk yard. A skilled muffler shop could fabricate an intake manifold or even use the stock manifold.
Barry
Barry Parkinson

It is good that Kelvin communicates with us as info from the source is always preferable to speculation - what we all seem to do best when partial or out of date info. is all we have.

Be grateful there are folks like him or Craig Cody who will communicate in some sort of dialogue, and newsletters like British Motoring. Some of our suppliers don't even bother.
Bob Muenchausen

TWM was at one point talking about offering a SU shapped throttle body.

If one wanted to do a port injection, why not base it around an SU manifold? put the injector prior to the cossover tube, add the runner length you want and feed it from a single plenum. Mount the throttle body in front of the plenum, and pick your throttle position from there.

There's enough TBI injection information out there for twin injector systems (see places like turbo city)that this should be relatively easy. Heck, it may be easy enough I may want to try it
greg fast

That's the one I was thinking of, Greg. Had a similar opening and air cleaner mounting flange. No bell, of course. One would use a pair of them ILO the carbs on a stock manifold.
Marvin Deupree

Might be a little off topic, but has anyone experimented with FI for the crossflow head.
Shareef Hassan

I'm still working on injecting my cross-flow car and have at least settled on a system thanks to Werner Haussman's help. I followed his advice and bought an L-Jetronic setup from an '84 318i. His articles advised that it was pretty much the same as the Renault stuff that he used on his car. It's an extremely simple system and is easy to adapt to an engine of similar displacement and can be run in either an open loop or a closed loop fashion. It can also be used with the stock injectors for a port-type installation on a cross-flow or with a Ford Tempo throttle body for use on a stock head using a ZS or a Marina manifold. The 318 also uses a neat wiring harness that can be removed easily without having to cut it to pieces like I had to do on the Ford EFI that I false-started on.

Anyone thinking about injecting an MGB should read Werner's articles that were in British Car magazine's June and August 1995 issues. He has it pretty much nailed on doing this simply and on the cheap. I'm in the process of fabricating my own intake to use port injection on my 7 port head, but if I were doing a stock head I'd surely try a Marina manifold and use Werner's method. I'll have way less than $300.00 in mine when I'm through including a bunch of mandrel bent tubing and a K&N.
David

Guess I will have to find some old copies of British Car. FI and computer control systems are truly the way to go, I think, and have definitely proven themselves as superior to normally asperated systems.

Sounds like Werner is on to something. I am a bit surprised that even at large national MG Meets, like the MG 2001 in St. Paul, there seemed to be little experimentation among the cars present (excluding the racers, of course). Apparently there is more interest than seems obvious if Moss is working on FI systems for market. We used to have an 85 318i so perhaps the system David and Werner used is not unfamiliar. It certainly seemed simple enough on the car we had.
Bob Muenchausen

This thread was discussed between 30/12/2003 and 09/01/2004

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.