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MG MGB Technical - Fools Rush In - Fuel Injection

I realize that this subject has been talked to death but I just cannot resist bringing it up again. I spent the last hour reading all of the relevant archival postings that I could find and I still have questions, so no one light the torches and grab the pitchforks just yet. Has anyone done any research lately on adapting OEM (junkyard) FI bits to sidedraught manifolds? I am specifically interested in a multi-port (4) injection for my cross flow head. I guess I must be a masochist, but I am curious if a common FI system can be used instead of my DCOEs. I know about the Megasquirt ECU and the TWM DCOE type throttle bodies ($$$$) and I realize that power gains should not be a goal when doing this. It just seems that with the huge number of different FI engines in the junk yards that some scrounging might pay off with better drivability.
Cheers,
David
David

The Slant Six guys are doing stuff with GM injection systems. Read a little

http://www.slantsix.org/articles/dibiase_efi/efi-conversion.htm

and you may be able to pick up tips on a 4 cylinder conversion
Greg Fast

I have done a good bit of thinking on a FI setup also- mostly to help with cool weather driving. The way I figure it is that you should be able to adapt a FI system off of a 1.8L engine from the 80's. Perhaps the system off of an import like a honda or mazda would do well. The biggest problem you will run into is getting everything set up properly and all the necessary sensors attached. I am not sure if you will be able to find an OEM throttle body that will fit a DCOE manifold. But it would be possible to make your own throttle body.
A throttle body is basicaly an injector, a piece of metal pipe, a device to control airflow, and a sensor to know how far the airflow control device is open. It is all pretty simply when broken down into individual componets.
I think it is just going to take somebody actualy doing the conversion and then giving us a report on it to tell us the do's and do not's .
Robert

David. Considering the advances in fuel injection, from the mid 60s to today, I think this would be an excellent way to go. For those of us who still have emissions testing (everything from 67 onwards is tested where I live), it would be a godsend. While the MGB engine will never be quite as efficient as the modern designs, I still think that adapting a modern fuel injection system would allow a better emissions profile while providing increased performance. I tend to agree with Robert. Someone is going to have to actually do the conversion, then write up the results. Ideally, a relatively recently rebuilt engine would be used. One that is broken in, but in excellent shape. Then, a rolling road (dynamometer) session before and after the conversion, to document what the actual results of the conversion are, would be in order. There are currently some aftermarket fuel injection coversions for older US cars and trucks. They cost about $1K to purchase and install. At a similar cost, there would be some market for such a conversion with the MGs. Les
Les Bengtson

David,
I can't find the link at the moment, but I once found a very thorough write-up on some of technical difficulties of installing port injection on cars with siamesed ports. The main problem is that there is some overlap when both intake valves on a port are open, and the first to open gets most of the fuel. (A lot if not most multi-port fuel injection systems fire all the injectors simultaneously and the fuel charge sits in the port waiting for the valve to open. Sequential injection, where the injectors fire individually, is more expensive and only recently became common, and only because of emissions laws). So you get one cylinder rich and the other lean. Not an insurmountable problem, but takes some clever design to overcome....
Rob Edwards

I think a Holley 1bbl TBI Projection setup could be adapted fairly easily, using the Pierce Weber manifold. These are sold for Jeeps, Ford 6 cylinder trucks and so forth. The Projection setup comes with a simple computer black box. You will need a coolant temperature sensor as well. A fuel return line to the gas tank is also required. An optional O2 sensor in the exhaust manifold is useful for dialing the mixture in. The main challenge is making an adaptor plate to mate the TBI to the manifold.
I installed the 2 bbl unit on an grey markey 83 Range Rover back in 1996 just so I could get through Ohio E-check. Such fun. It worked quite well the three years that I owned it.
I'll stick to a goood pair of SUs for now, unless I install that supercharger....
Andrew Blackley

IMHO,
The SU carburator is a superbly designed unit permitting fine tuning of any aspect of performance. The missing ingrediant is a pair of oxygen sensors in the 1&4 Manifold plenums. Switching sensors between fore and aft carb will show the operator exactly how the units are performing under real time conditions. It is this sensor feedback loop that "makes" EFI.
Doug
D Sjostrom

Rob,
I have a cross flow head with four intake ports hope that FI may be simpler than with a stock head.

Robert,
I read in one of the threads that the Ford Topaz used horizontal 40mm throttle bodies. I'm going to go the the junkyard tomorrow and look around.
David
David

'Scuse me... Ford Tempo/Mercury Topaz.
David
David

David; I think this may be the reference Rob mentioned.
http://www.planet.eon.net/~chichm/efi/efi.htm
Several years ago an MGB owner installed a fuel injection system from a Renault Fuego in his MGB. I think the article was in an AMGB magazine, but I couldn't locate it tonight. He sometimes posts here, I think his name is Werner Hausserman (Sp). I believe the Renault used a Bosch system. FWIW, Clifton
Clifton Gordon

Thank you very much, Clifton. Excellent info.
David
David

Hi David

Using a 4 port head solves the problems associated with converting the MGB to EFI. With the 4 port head you can make it a modern EFI engine. I have only played with the factory head.

With the 4 port head you can use the many off the shelf custom EFI systems. Most of these are not supported with the existing MGB head due to the siamese ports. But it takes $$$ and some work.

If you use a junk yard injection system, I recommend you use the Bosch L-Jetronic. It is readily available, was designed to be used as an 'Add-On' for existing engines in the 80's, and when installed will not require any calibration on a Dyno (although checking it is a good idea). I have been able to get two systems like this for <$200 each. When you do get one from a Junk yard, you need to get the injectors, CPU, and Air meter from one car so it fits together. Choose any engine from 1600 to 2000cc. You may need additional bucks for trottle bodies. Once you have it all working you can upgrade to a custom system for $$$.
If you wish, send me your address and I'll mail you the write up from the British Car magazine June and August 1995. If you find one from a Renault Fuego or Alliance I'll help you with schematics etc. Consider looking at the classifieds for a running one and offer $150. These cars are still available, but noone wants them. The EFI is identical to that on a BMW except for some adjustments.

To start I suggest you get one or both of these books and read them multiple times.
1. Bosch Fuel Injection & engine management by Charles O. Probst
2. Fuel Injection, Installation, Performance Tuning, Modifications by Jeff Hartman

Also check out the links here;
http://users.exis.net/~audserv/Injection.html


Let us know how you make out.
regards
werner
werner haussmann

Werner,
Thanks, I've e-mailed you my address.
David

David, you may like to have a look at the British Patent GB2266923 which gives a little insight into what Rover Group were doing ten years ago. (You can find Patents via the European Patent Office link http://www.european-patent-office.org/espacenet/info/access.htm)

Mike
Mike Standring

Clifton,
That's it! Cheers! I was think specifically of this page:
http://www.planet.eon.net/~chichm/efi/siamese.htm
Rob Edwards

David,
The Ford SEFI is a good choice. It is sequential, it has adaptive software, and it is readily available at a reasonable cost at most junkyards. If you can pull one off a car of comparable size with a comparable displacement it will probably work without any modification other than those needed to make it fit. The downside, is that if you need to tune it the plug ins needed such as the "tweecer" are rather expensive at around $600, and you need to make sure the processor you plan to use is supported. Many 4 cylinders are. There are a rather dizzying number of parameters that can be tuned using this method, so the package is about as flexiple a one as you will find. Check the threads on the V8 board for more info.

Jim
Jim Blackwood

Warner; Sorry about the spelling of your last name. I located your articles in British after posting my response.
David; Here is a Renault Fuego on eBay to give you an idea of how much they bring. There should be some of them somewhere in your area.
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=2448346013&category=6385
Clifton
Clifton Gordon

Clifton,
Thanks for the tip on the Fuego. It certainly is cheap enough right now. I've sent the guy an e-mail to see if he is willing to just send me the FI bits if I'm the high bidder. In the mean time, I'm off to the U-pull it to look around there too. It looks as though I can use my Weber manifolds by just installing injector bosses in them and fabricating a plenum from sheet metal to bolt onto them and then attach a throttle body to that. There is plenty of room in the engine bay to do a clean job of it.
David
David

Good catch Clifton, $50!!!! for the Fuego

The '83 Fuego also has a weber trottle body that will likely fit on Dave's manifold.

Clifton, can the article be accessed on the web? That would be quicker for Dave than me sending it.

werner
Werner

You wil also need the Black Box.
FWIW heres a link to the Holley Fuel Injection site. Might be soemthing her eyou can use: http://www.holley.com/HiOctn/ProdLine/Products/FMS/FMSFI/FMSFI.html
Andrew Blackley

I just got back from my secret discount junk yard with some plunder. I found an '88 and an '89 Escort GT with 1.9 HO engines and Bosch EFI (non-sequential). My cohort and I wrenched for a bit and walked to the checkout with 2 MAF sensors, 1 throttle body, the fuel rail and 4 injectors, the harness stubs and connectors and a Jetronic ECU (I don't know the application, it was laying loose on the hood of a Chevy). The total was $54.00 includung tax with all parts guaranteed. I could not find the Escort ECUs to save my life and will have to go back for them after I do some reading. I did take note that the Ford MAF sensor appears identical to the one on my 3.5 Rover EFI.

I have a couple of items that will also need clarification as well. I don't know how far back in the manifold from the port the injectors must go, how large the plenum should be and if the stock Escort throttle body is large enough for my application.
David
David

I put a ProJection system on a marine inboard. Great products. Horrible company to deal with. I never did succeed in getting to an actual live person regarding technical questions.
Doug
D Sjostrom

Werner, I couldn't find your article on the web. If Classic Motorsports (formerly British Car) have their articles archived I couldn't locate them. I found your article by looking throught my back issues of British
Car.

Clifton
Clifton Gordon

David,
It seems unlikely that an '89 Escort would have a Bosch EFI system. More likely to have the Ford EEC-IV I believe, especially since you say it had a MAF sensor. However, you have a good start. First thing is to determine exactly what system it is and get all the right parts for it including all the sensors. Used ones are OK if they work. Get the right controller for the car, even if you have to order one from a reman and you will save yourself a lot of work. Try to get a controller from a manual transmission car.

The 1.9 HO system will be just about right as far as size, or maybe just a bit oversize. The processors were probably gone because they were snagged by people who had non-HO cars doing performance upgrades. A non-HO processor would probably work fine.

For more information you really should visit the tweecer website and bb. There you will find a ton of info on 4 cylinder applications and a list of supported processors. Don't try to make a non-supported processor work, it's a dead end.

Jim
Jim Blackwood

If you have 4 ports, why not go with a Megasquirt and the individualthrottle bodies and injectors from a large sports bike? The throttle bodies seem to be plentifull on e-bay, and the megasquirt seems like a do-able project in itself.

Pete
Pete

Jim,
Thanks for the info. I assumed that it was a Bosch system since the air flow meter was the same as my SD1 system and I was always told it was really a Bosch. I couldn't even find where the Escort ECU's were mounted and I ran out of time. I looked under the seats, behind the glove box, behind the kick panels, in the boot area, etc. I could find no evidence of where one had been removed. The guy at the breaker's said that they were still in the cars and that I just hadn't looked in the right spot.

With the EEC-IV is it mandatory to use all of the original sensors? Would I be better off with the Renault FI?

Pete,
While that sounds like a good idea, I want to get something that I won't have to spend a lot of time setting up.
David
David

Well, I found the correct ECU for the Ford EFI and now will try and determine what minimum inputs are necessary for the system to function. I also need to fab a plenum. The plenum design is my biggest concern at the moment regardless if I use the Ford parts or not. All of the cars that I see have tuned runners and I don't have the knowledge to duplicate that. I'm wondering if a log or a box type intake flanged on the side and bolted to my Weber manifolds with the throttle body attached to one end would work OK without any runners. Velocity stacks would be used inside. Anyone have any input?
David
David

If you connect a large box to the input side of your webber manifold the manifold will become your runners. The runners simply help in the ramming effect of the air, you have more air volume moving and when the valve shuts the air keeps on moving and then builds pressure behind the valve. When the valve opens again the air is atill moving slightly and it takes less energy to get the air up to velocity again.
-I built a manifold for my SU carbs, it is about five inches in overall length, the idle is lumpier but you can feel more power after about 2500 rpms when the air velocity begins to pick up.
-Good luck, do let us know how it turns out, even if it is a flop.
Robert

David,

This is an MFI system. The injectors are ganged into two banks of two. For all practical purposes the difference between this and a full sequential system is only important for emissions control.

Go to helminc.com and buy a schematic for the Escort ~$15 and preferrably the electrical/vacuum manual as well ~$20. I would also recommend the Probst book on Ford fuel injection systems. These will be infinitely helpful. The one sensor you have to have for it to work is the crankshaft position sensor, but it will work better as the other sensors are added. This sensor should be located in the distributor, which means you will have to either find a way to mount it in your distributor or adapt the ford distributor to your engine, or go to a distributorless system. This third option will be difficult with the earlier MFI.

Ideally your runners would be the same volume as the cylinder's displacement and the plenum would be the same as the engine's displacement. However it isn't at all critical for a street machine, and can cause the engine to become 'peaky'. The simpler the better at this point. You are biting off a large chunk so don't make it bigger than it has to be. Time later to go back and redesign what you like.

Jim
Jim Blackwood

Thank you, Jim. Crank position sensor, huh? Maybe I should use a dumber, more primitive system than this one. I don't mind the work involved in doing this and I am able to do all of the fabrication and mods myself but I really want to keep it as simple as possible. Werner has kindly mailed me some info on his adaptation of the Renault FI and I will wait until I get that before I go any further. Your advice on not taking too large a bite is wise.
David

David, Noticed K Dodd of Moss motors mentioned FI with a cross flow head in one of his relplies to a question on supercharging.He mentions Ford or Honda. Maybe you could give him a call and see how deep he has looked into the FI on a crossflow head.
Jack

Modifying the Ford distributor to fit the MG engine is how I would try to go. A bit of machine work to match the MG stub (Huffaker used to do this with Mallory dual point distributors, it might even be possible to get a mallory to fit the MG with the Ford trigger.) and an ignition that will work with the Ford trigger should be all that is needed. However, you then get into the other sensors. Some systems do exist which can run off just the tach signal and the throttle position. Megasquirt is such a system and worth looking into. This is a batch fire speed density system. For simplicity that's hard to beat. I believe the early Bosch systems worked that way, although an airflow meter was also common with some systems.

Jim
Jim Blackwood

"The simpler the better at this point. You are biting off a large chunk..." I think Jim is right on.

Most later systems (designed for the car) use crank position sensors. The earlier systems (1980's, BMW, Jaguar, & Fuego) used the Bosch L-Jetronic system that only requires a tach signal. Some of the Simple system off the shelf also use a Tach signal.

Another consideration is how the air flow is measured. If you use Manifold Absolute Pressure sensor, then you have to map the head flow over the full rpm range on the dyno to get good results. If you modify the head, you have to do it again. Essentially each head design flows a bit different depending on manifold pressure. The Air Flow meter of the L-Jetronic measures the air flow independent of the head. If you get the Air Flow meter, the ECU (black box) and the injectors, the L-Jetronic system is basically calibrated. Of cource you need the cable and temperature sensors as well. but they are common between many of the cars with this system. The ECU, injector, and Air meter go together almost like a bolt on Kit. This was the first good all electronic system most car makers started with. It was designed to easily add on to existing cars.

As Jim said above. Once you get it working, then you can upgrade.

First focus on getting an extra fuel line, fuel pump, the injectors mounted, the fuel rail and fuel pressure regulator mounted, etc. there is plenty to do.

Do get the Bosch and Hartman book. Don't start without it. It's all in there.

Dave I send the stuff out today.

werner
Werner

Werner,
I did a search and found a BBS post you ref. the later L Jet using vacuum instead of the MAF switch to enrichen the mixture. Did you ever do this and do you know what applications used that type? I'm going to Barnes and Noble right now to buy/order the books you and Jim suggested.



"DIY_EFI Digest Tuesday, 5 March 1996 Volume 01 : Number 065

The L-Jetronic uses the trottle position to change the A/F ratio. At about 2/3 full trottle a switch closes and enriches the mixture. Later versions of the Bosch system used manifold vacuum to activate a switch. I want to change my system to this method. I want to enrich the mixture when the manifold vacuum drops. I want to enrich the mixture when the manifold vacuum drops."


Thanks,
David
David

No I have not used the Manifold pressure to determine enrichment. This is a bit difficult because you need to do it at a certain calibrated level. Not just wide open. As a first pass I recommend you leave the enrichment on all the time. The way this usually works is that normally the engine is run very lean using the oxygen sensor. At 2/3 trottle the oxygen sensor is turned off and it is run under 'enrichment' This is roughly the same as the 'normal' setup on an SU carb (3.5% to 5% CO reading)

If you decide to go with the L-Jetronic, I suggest you not use the oxygen sensor for your first pass. This means don't use any of the trottle position information at all. Don't bother with the oxygen sensor until it all works and the engine gives at least as much power as the SU's. The oxygen sensor will give better cruising MPG. There are two trottle positions required. 2/3 trottle and closed trottle.


regards
werner

Werner

Werner,
I received your articles yesterday. Thank you very much for taking the time to send them. They are very well written and answered a lot of my questions. I'm off to the scrap yard tomorrow.
David
David

David.

Here is a decent resource for How to build a...intake manifold, fuel rail, turbo exhaust manifold etc....

http://www.sdsefi.com/tech.html

They manufacture a relatively low cost ecu for diy fuel injection.

Regards,

Brian
Brian Corrigan

Here is a source for Throtle Body FI that incorporates a Weber DCOE intake manifold. It may be of some interest.
http://www.twminduction.com/ThrottleBody/ThrottleBody2900-FR.html

Wil
Wil Heslin

Hi,
Been watching this thread for awhile now.. why not use the complete TBI system from a Pontiac Tech 4? Its a 2.5 liter engine system and has the bugs worked out. Use the ECM AND wiring harness that goes with it. I think that due to the strange (siamesed valves) head design of the MGB, a port fuel injection system would not work as well as a TBI "wet" system. The injectors on a TBI system would be further away from the intake valves and allow the charge a chance to smooth out, the scavenging effects would not be a problem. With the TBI injectors mounted on a home made log style plenum with outlets at each end connected to the SU manifold where the carbs used to be... could work and the EGR would be easy to incorporate for emmission control. Distributor would have to be modified to work with the ECM easy stuff. FWIW Alan
Alan

This thread was discussed between 14/12/2003 and 22/12/2003

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