MG MGB and MGB GT Tech Talk
Race day today - so I thought you might want to see a club member's fuel injection system he built for his car.
The fuel injection works quite well - pity the engine started making very loud clattering and banging noises during the last round of the day was soon parked for the weekend!
So is there a class down-under that allows FI in a 'B?
How did the car run before it's ailments set in? And what parts did use to put this together?
He has actually run this EFI for some time (this is just the first time I have been able to take a short of it - the car was "broken" and the bonnet was up :) ) Yes, the car is normally fast. What is in the EFI? I would need to sit down and buy him a few drinks to MAYBE get more detailed info, but probaby wouldn't. The photo is about it for now.
What broke? Even he had no idea but he suggested it souned very expensive
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As for a class that allows EFI? In this event there were four classes. Street (unmodified), Modified, Specials and Racing.
"Racing" cars run superlightened (fibreglass panels etc) and run slick tyres.
The other classes allow for various modifications and levels of modificantions - some you can hide to get away with being placed in a lesser class to your advantage... some you can't. Much of it is self-disclosure, gentleman's agreement stuff. Some of us are more gentlemanly than others and some "slop" between the classes is accepted for mods which really don't really benefit a car in certain circumstances. BUT because this is State versus State you should not count on getting away with anything because "they" will have spies hunting for any advantage for their State.
For instance - one year I got bumped up a class for "lightening" because I run without a front bumper, which is allowed in the competition I normally run in and which is now allowed in this competition (after that incident) because it has been written into the rules. How much "weight" is there in a chrome bumper?
And why I have I told you all this in response to your simple query? Because I got "caught" for an indiscretion which meant my car got bumped into the "Specials" class... which means I ran about middle to bottom of the field instead being in contention to win in the "Modified" class (and obviously I am stewing over it... OK!!!).
I'd love to see details on his setup. And more larger pics for closer study. Bet others would, too!
Hey, I am not sure he would be happy me taking shots under his bonnet in te first place :-)
Nahhh, he is probably OK with it - we all play at being more secretive than we really are. We aren't playing for sheep stations (or "cattle ranches").
I will see what I can get out of him :)
Looks like a regular SD system (no visible AFM), long intake runners to keep the wetted intake volume up (note the injectors adjacent to the throttle bodies. this is closer to a TBI type system as it's known in the US rather than a true port injection system. The issue with FI and charge stealing that occurs with 'port' injection is pretty much eliminated as the injector moves further away from the port.)
My only question is what controller he's using and injector size (Injector size, if optimized, may get you a ballpark read on his output, if the injector is optimized for best mapping.)
And a buddy of mine who was running an Improved Touring Cortina in SCCA had the same deal happen to him. A guy hooked his bumper on the false grid and bent it all to crap. Only way to safely run was to remove the bumper, and he was protested for illegal lightening. Wonder what would have happened if he'd tried to run with the bumper sticking out 2-3 foot in front of the car like a harpoon.
I made a setup very similar to this using throttle bodies out of a CBR 600 motorcycle (36mm). The computer is a Megasquirt. It runs extremely well! I was getting 19mpg in town prior and I now get 26. Freeway trips get around 34. My oil stays clean and the plugs are spotless. I also removed my distributor and the computer controls the ignition as well.
It was a lot of work but well worth the effort. Total cost was $850. I tried 4 different injector manifold and injector designs and ended up with the twin throttle body setup like his.
If anybody is interested I am more than willing to send pics or advice!
Tyler Madia
Seattle, WA
'73 BGT
'59 A
'58 Magnette
Tyler, welcome aboard. Would you mind posting a pic or two of your setup. It sounds quite interesting.
I still haven't maaged to get much more detail out of the guy with the car pictured above. I believe he is going to write an article about his setup for the club magazine and I will pass it on here if/when he does.
twentyover Wrote:
Hey Paul!
The intake runners are as long as I could make them to decrease the adverse effects of the port robbing. For each revolution of the engine the injectors squirt 4 times, again to attempt to produce the most homogenous mixture possible.
It must work pretty well because I can rev it up to 5500 quite easily whereas with the carbs it didn't want to go past 4500.
The crossflow aluminum head would have made this a very easy exercise and it would run better to boot. If they weren't so dang expensive I would have one. The only drawback so far has been programming the amount of enrichment for when you quickly open the throttle all the way. Driving around town it is superb, but if you suddenly floor it there is a second of hesitation. I'm sure it can be programmed out but I suspect the long intake runners are making that difficult.
I have just purchased a used Eaton supercharger so my summer project will be to fabricate a manifold to fit it to the engine. With the computer controlling the fuel and the spark I can't wait to see what kind of trouble I can get into!