'71 MGeo MPG Project
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Author:  nimblemotorsports [ Fri May 28, 2010 11:19 pm ]
Post subject:  '71 MGeo MPG Project

Hello, I recently purchased a '71 MG Midget that I'm building with my 16yr old son,
and my plan is to make it a high-MPG machine.
I have a G10 motor (1.0 3cyl from '89 Metro) that I'm putting in it.
As the MG is a RWD, I got a 5-speed RWD trans from a Geo Tracker.

I've built many cars over the years (I have a 3-wheel EV in progress too),
the biggest project was a '63 Falcon roadster complete frame-up build with a custom stroker 506ci Bigblock.

I have many ideas for this engine and car. Obviously I'm going to lighten it up as much as possible,
fiberglass hood, maybe fenders, trunklid. The G10 motor and trans is big weight savings already.
I may just put in the stock G10 motor and get the car running for now, and build a superMPH motor
in the garage to swap in once its complete and testing.

I've been trying to research the issue of water injection. Mill the head, and increase compression and
then use water injection to prevent knocking and further increase efficiency.
But I haven't read much about its success in these forums. Was anyone tried it?

Another related idea is to run the motor as a 6-stroke engine, in which after the 4-strokes,
another power stroke is done without using fuel, just the water injection.
Some research shows this works well, and with a 3-cyl, it will balance out the engine well.
This seems like a very interesting approach that might boost mileage greatly.
It will require a custom EFI setup. So another issue is converting the head to use port injection,
then the intake manifold can be replaced with plastic runners and plenum.

As I've done EV work, another plan is to add an electric motor to replace the starter and alternator,
but let's leave that one alone for now.

Thanks for any suggestions!


Author:  nimblemotorsports [ Fri May 28, 2010 11:53 pm ]
Post subject:  Re: '71 MGeo MPG Project

Here is a pic of my Falcon with the 506ci Big Block. It got about 8mpg! :)

Author:  suprf1y [ Sat May 29, 2010 6:05 am ]
Post subject:  Re: '71 MGeo MPG Project

You can buy a head (or drill the stock one-the bosses are there) and intake from a Canadian factory turbo car for the port injection setup.

Author:  nimblemotorsports [ Tue Jun 01, 2010 2:04 am ]
Post subject:  Re: '71 MGeo MPG Project

I've dusted off the G10 motor and tried to mate it up to the Tracker 5-speed,
and unfortunately they do not mate up directly. The bottom two studs on the Tracker bell housing
don't line up with the G10. Is this normal or do I need a different bellhousing?
The tracker was a '91, my G10 is an '89 I think. thanks, jack

Author:  suprf1y [ Tue Jun 01, 2010 6:52 am ]
Post subject:  Re: '71 MGeo MPG Project

Thats the G16 bolt pattern.
The Samurai bellhousing should bolt right up.

Author:  nimblemotorsports [ Tue Jun 01, 2010 6:19 pm ]
Post subject:  Re: '71 MGeo MPG Project

OK. Does the G16 bellhousing have the same center line for the trans as the G13?
In other words, can I just modify the bellhousing for the lower mounts, and
the upper mounts are correct for the trans positioning?
Thanks, jack

Author:  nimblemotorsports [ Wed Nov 03, 2010 12:19 am ]
Post subject:  Re: '71 MGeo MPG Project

I'm back to work on this project.
I have a Samuri Trans now. I trial fitted the motor+trans in the midget, it fits easily if located
in the same area as the stock engine. But I want to set it back a lot to make room for the electric motor
in the front.

I've got the engine on a stand now, getting ready to try and get it running on the stand in stock form.
Once I get the wiring figured out and have it running, I will be replacing the distributor
with a Coil-On-Plug distributorless ignition that I will be creating using one of my MSP430 microprocessors.

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Author:  Phil N Ed [ Wed Nov 03, 2010 6:26 am ]
Post subject:  Re: '71 MGeo MPG Project

This build might be a little different than your ideas, but a fellow in Ohio has a similar engine:
Have you seen it?
He's dropped the coil
but I'm not sure he ever got it completely together

Maybe shoot him a PM???

Author:  nimblemotorsports [ Wed Nov 03, 2010 10:15 am ]
Post subject:  Re: '71 MGeo MPG Project

thanks for the link, I have not seen that since I have no interest in a turbo.
I see he is using a MegaSquirt. That would be easier, lots of support for it.

Author:  nimblemotorsports [ Sat Nov 06, 2010 11:22 pm ]
Post subject:  Re: '71 MGeo MPG Project

The engine is running! Going through all the wiring was a major pain!
Took me three days to sort through it all, finding diagrams, tracing, etc.
But its all done and now running pretty well, though I can't really rev it up too much,
since it will vibrate the stand across the floor. I guess I could put some lugs
in the concrete floor. hmm.

If anyone is familiar with the ECU, there is a speed sensor, what does it do, what effect does it have?
I didn't hook it up. And it seems the ECU doesn't have an engine temp input??
Just a temp switch to turn on the e-fan, and another for the idiot light?
It seems a pretty simple EFI.

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Author:  t3 ragtop [ Sun Nov 07, 2010 9:38 am ]
Post subject:  Re: '71 MGeo MPG Project

the fan switch and temp gauge sending unit are on the water neck by the t-stat. the coolant temp sensor is on the intake manifold and the intake air sensor is in the air filter hat. yes, the ecu does have temp inputs for clt and iat and they are both important. clt enables proper closed loop operation and the iat is important for fuel trim.

the speed sensor, vss, is a part of the speedometer and it generally holds the idle speed up when the car is above 15 mph. people usually report idle hunting or surging while compression braking as part of a bad vss. there is a secondary vss on automatic transmissions that i believe is part of the atcu controls.

hope that info helps.

Author:  ranger88den [ Wed Mar 23, 2011 2:01 pm ]
Post subject:  Re: '71 MGeo MPG Project

Any progress?

Author:  nimblemotorsports [ Wed Mar 23, 2011 2:31 pm ]
Post subject:  Re: '71 MGeo MPG Project

ranger88den wrote:
Any progress?

yes, quite a bit, i've moved the discussion over to,


Author:  ranger88den [ Mon Mar 28, 2011 11:12 am ]
Post subject:  Re: '71 MGeo MPG Project

Thanks for the link. I'm enjoying your project.

Author:  91CavGT [ Wed Apr 27, 2011 6:51 pm ]
Post subject:  Re: '71 MGeo MPG Project

I'm not on Eco modder but I do have experience with water injection. I have used it on 2 cars so far.

The last car I had it on was a 2003 Dodge SRT-4. I was able to run high boost (19 psi) on pump gas while actually having more ignition timing than what it had without water injection with stock boost (14 psi). So more timing is DEFINATELY possible while running lower octane fuel than what you could normally run.

I had a Suprfly head on my '96 Metro that was running 10.5:1 compression and I had to run 93 octane fuel. If I had water injection on it, I could have run 89 octane fuel without knock.

I think the best way to go about installing water injection for fuel economy is to get a controller that can control either pump voltage or injector pulse width depending on the amount of vacuum in the intake manifold. Less vacuum, more water injected. More vacuum, less water injected. You are going to need some VERY SMALL nozzles. As far as the pump, you will want at least 40-60 psi at the lowest pressure to ensure good atomization, but of course the nozzles will really determine how much pressure you need.

Now as far as other potential ways to increase FE, here are some ideas that I have.

1. Get rid of all the accessories that run off of a belt. So take off your alternator and water pump (or just take the impeller off of the water pump).
2. Remove the thermostat.
3. Install an electric water pump that is controlled via a thermetic switch that turns the pump on at 195 degrees and turns it off at 180.
4. replace all the lights in the vehicle with LED lights.
5. Install a solar panel on the trunk of your car. I currently have a 43 watt panel that is 21" X 26" and it puts out 2 1/2 amps in full sunlight.
6. Replace the factory battery with a large AGM battery. I recently bought some AGM batteries in 140 amp/hr size (it can deliver 12 amps of current non stop for 20 hours) and they weigh in at about 70 pounds.

You would have to perform all 6 things listed in order to decrease the parasitic draw on the motor. The water pump and alternator take a rather large amount of power to turn at cruising speed. I have found electric water pumps that draw less than 4 amps, and in the winter or while cruising on the highway the pump won't be running all the time. You would be adding some weight though, approximately 15-20 pounds but that should be negligable.

Another thing to do to increase mileage is to decrease aero drag. Grill block, remove external mirrors (replaced with internal side view mirrors), belly pan, and a rear boat tail are just a few things you can do.

Author:  Bret Maverick [ Mon May 23, 2011 12:22 am ]
Post subject:  Re: '71 MGeo MPG Project

How are you going on the project? I am going to use a Samurai trannny on a g13bb in my 1979 Midget. Was wondering about modifications to the tranny and driveshaft tunnel, and motor mount fabrication. Would appreciate any help.

Author:  werase643 [ Wed Jun 15, 2011 8:35 pm ]
Post subject:  Re: '71 MGeo MPG Project

one bad thing about the sammy tranny
no speedo drive
it's actually on the transfer case

i'm S-L-O-W-L-Y building a T-3 in a 59 frogeye....i am going RHD to make the ex clearances easier

Author:  werase643 [ Thu Jun 16, 2011 8:29 am ]
Post subject:  Re: '71 MGeo MPG Project

I read your 14 page build up on the other site
another concern i saw is/was the custom steering column
that was one of the AH problems and you copied it from what i saw
consider a couple of unions to act as collapsers
in a FE coll. the steering wheel will try to stab you in the chest since it is a 4 ft spear

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