Inliners International Forums General Discussion Engines 250 tbi, any tbi guys out there?

I would like to install a tbi (electronic fuel injection) onto my 250 L-6, the problem is that they are only available for "even fire" sixes. Are Chevy L-6's "even fire"? Some friends are telling me that they are not. Where can a guy get a L-6 tbi system? Can the software be altered for non-even fire sixes?
Any help would be appreciated.
Dano

Clifford performance offers a bolt on EFI system I think it is about $2500 though, check out their website.

Yeah that Clifford unit is pricey, but it seems that they modified the computer or software. It bothers me that they mispelled computer 3 times.
I was wondering if modifying the computer/software is easier to do than having an "even-fire" crank made up. Of course the dizzy would have to change also (V-6 dizzy?). What would happen to the L-6 if it were even-fire?
Anyone know how to reprogram or modify the computer and or software?
Dano

Dear Dano;

These types of systems are not cost-effective for general usage etc.

A single 4bbl & headers will do just fine, unless your planning an "all out" racing engine/vehicle.

Good luck, John M.....

goto www.msefi.com megasquirt do it yourself injection.

For US$150 you build the efi controller, guys on the MS site are building partial harnesses, get the rest of the system - pump, fuel lines, engine harness from the junkyard. A little bit of wiring later to splice the 2 harnesses together and your done.

For under US$500 you can convert to injection. You will need a laptop to tune the system. As of last month their were over 7000 MS controllers sold. All the required tuning s/w is free on the net.

Just a quick note I'm been running the MS for 3 years now. And no I'm not involved in selling it, just a satisfied user.

If you dont mind the work you could go with the megasquirt setup for computer control. As they say its the "Do-It-Yourself programmable electronic fuel injection controller." Here is there website http://www.msefi.com/

Good luck,

well I guess efi-diy and I were thinking along the same lines at the same time!!!

dano, I don't think that for a tbi it would matter what firing order the engine uses. TBI's are essentially just electronic carburetors, they inject fuel at the same place a carburetor would be.

The clifford kit, is port injection and includes a bucnh of stuff such as new intake, damper, I think even a camshaft plus all the required efi hardware.

I'm under the impression that really late model 250's had a 2 barrel tbi efi system. Is your engine an earlier or later model (does it have the intigral head)

you may also try changing your intake for a four barrel type and getting a TBI system from a V8, I figure it should probably work..

Or if you like a challenge, make your own setup with efi components from other vehicles and using a Megasquirt controller.

In my opinion, if you want efi, no hassles and you've got cash, get the clifford system. If you don't have cash and are don't want much of a challenge try finding one of the late model tbi setups, or try changing the intake and use a V8 system.

If you really like a challenge, get megasquirt, replace the intake with three individual throttle bodies from a cavalier or something (one per port) and put in fuel injectors right at the port so you have a full port injection system (with individual throttles!!!)

If you have a VERY large budget, go to brasil and get a "new" 250 from a '95 chevy omega (they have EFI, port injection, even distributorless ignition!)

Luis

Last year a buddy and myself converted a Ford FE 390 V8 from carb to megasquirt in 14 hours using a TBI.
We started with a assembled and bench tested Megasquirt, then built everything else including modifying the fuel tank, running the fuel lines, installing a EFI fuel pump, building a harness from a junkyard Chevy G van, getting it running with a decent tune up that was good enough to get him to work the next day.....

So its not that tough, although we had done a MS install before, so even if you double your time it will not be more than that.

All right!
Yeah I'm a do-it-yourself kind of guy with more time than money.
Thanx for the info on megasquirt efi-diy, glenfred and luis brw. I'm gonna go for it. I have always been a carb guy, but I'm also a computer guy. I just thought that I'd mesh the two together and get up to date and into electronic fuel injection.
It seems like its going to be a challenge, but I'm up for it.
Dano

there is another guy around here making his own port injection setup using megasquirt as well..

cant remember his name he has posted some pics of what his intake will be like etc. I think he was going to use dual throttles.

I was once considering getting an eaton blower from a GM 3800 engine and making an efi setup based on that, (the eaton blower has the throttle body already attatched).

My other idea was the one I mentioned earlier, using three throttle bodies, but I was kinda liking the bower more..

But for simplicity tbi would be the way to go. Now something I like about port injection is that you don't need to worry about plenum heat as you would using a tbi or carb...

Just some of my thoughts on the topic.

Just for everyones general info, our 6's are indeed even-fire. I talked to Holleys reps once about using their Commander Series TBI and they said it would work just fine, it would just be a matter of tuning.

A TBI sprays fuel above the throttle plates just like the discharge tubes on a carburator. You still have the carbs. problem of a wet flow manifold with the seperation of air and fuel. I think a well tuned carb. would be cheaper, less work, and very little if any performance difference.
my $.02
Jim

Jim R,

The biggest difference is in tuneablility with efi you have far more control over the A/F ratio that 99% of the carbs that exist. And to get the same performance over the same rpm/load range with a carb vs efi it takes an expert knowedge of the carb. I agree that at a given rpm/load point a carb can be tuned to be better than efi, not over the whole rpm/load range.

My 2 boxes of holley tuning parts have not seen day light since I converted. No more leaking gas over the engine to change jets, just a couple of key strokes and your done. Does it take longer - yes since you have more points to tweak.

Once people "get over" the inital "what do I do now" hump - yes I had it too, and start tuning very few people go back. Did I carry a holley in the trunk for the 1st summer - yep. Do I carry a spare MS controller now - yep.

I don't think doing a port injection wouldn't be that big of a deal anyways. All you'd need to do is put injector bungs on the manifold which shouln't be too hard...

one of the things that intrigues me the most aboutr efi, is that you could potentially have a switch to change from power mode, to economy mode, to emmisions mode.. and drive around with whatever setting is convienient at the moment...

imagine being able to dirve around with low fuel consumption but instantly turning up the fuel for power..

kind of interesting don't you guys think?

As a former owner of a Buick 225 Oddfire V-6, I can explain why the TBI unit doesn't work with it. The oddfire V6's had 120 degree crankshafts, which made the left and right cylinder banks fire at odd times, since the V was 90 degrees. The engine would fire off one bank, rotate 90 degrees, fire off the next, and then rotate 150 degrees until the next bank fired, rinse and repeat. It ran a lot like a bunch of Harley motors in a gang. Because the cylinders don't fire in a monotonic pattern the TBI computer gets confused and doesn't calculate the RPM correctly. You can trick a TBI computer into running an oddfire engine by making a crank angle sensor to trigger it instead of using the ignition. Later GM V6's were even fire. A TBI setup for a 3800 V-6 should be easy to adapt to an inline engine, only the firing order is differant. Even fire V-6's fire every 120 degrees just like inlines.

is that all? the computer confusing the timing? wow the people at mega squirt made it sound like it was impossible to set it up a mega squirt for an odd fire engine.. all one would have to do then is install a crank position sensor..

efi,
I wouldn't use Holleys for a street machine either as they just can't be tuned right. Too many "holes" in the fuel curve. You need a carb with a jet needle. The cost of a laptop alone would exceed the cost I'd want in a complete carb setup. I'm not arguing with your choice - I just don't think I could justify the amount of money it will take to convert to a TBI. Now, port injection on a head with 12 ports where I could take advantage of excellent fuel control and be able to "tune" the individual runners might make me unzip my wallet.
Jim