Inliners International Forums General Discussion Hi Performance 292 with TBI and megasquirt

I finished the debug on the GM TBI to megasquirt adapter board today and unbolted the holley 4bbl and bolted on the TBI injector using an adapter from holley to my offy intake. Hooked the fuel supply and return line to the TBI, plugged in the adapter board to the stock GM harness, then plugged the megasquirt into the adapter board. Hooked up the HEI neg. terminal to the tach input on the MS and turn the key. Fired on the 2nd shot and ran fine considering it was using the default fuel curve.

So a $500 EFI setup with no/minimal (usually just to delete unneeded wiring in a retro-fit appplication) wiring hassels is now possible...

The Adapter boards will be ready for regular folks in about 2-3 weeks.

For 194/230/250/261 applications get a TBI unit out of a 88-92 4.3 V6 astro van, for 292 get one out of a 88 -92 full size pick up truck with a 350. You can keep your point distributor if you wish - better if it has the pertronix kit. The only gotcha is you need a 12V electrical system... no one every has made 6V injectors..

A couple of vids and some pix - note the real high tech throttle hookup - its only a temp set up.

http://img261.imageshack.us/my.php?image=dscf0006uk8.jpg
http://img340.imageshack.us/my.php?image=dscf0006it7.jpg
http://img358.imageshack.us/my.php?image=dscf0007om9.jpg
http://img532.imageshack.us/my.php?image=dscf0003ul9.flv
http://img532.imageshack.us/my.php?image=dscf0008ps5.flv
http://img532.imageshack.us/my.php?image=dscf0009mh2.flv

Man,
That looks like one of my installs I LUV IT!
Spent lot of years trying to put together something no one else had,woke up lots of nights with fixes in my head that had to be tried right then before I forgot! I have a Cummins Diesel in one of my 1949 3800 series trucks and love it!

is there sound with the vids? i can't hear any. neat approach to a hard task for many. can you set up the mega sq boxes and have them programmed for guy's to drop in and run? tom

did fuel injection come on later model 292's, and if so why doesnt everyone use it? what kind of hp improvements can be expected from tbi or mpi over lets say a 500 or 600cfm edelbrock? I saw a tbi on ebay for a 250, he said it only got 14 miles to the gallon! wheres the advantage? fuel injection is supposed to get better mileage and deliver more hp and torque, I see that mileage is not better, what about power? plus they are way more work! I love fuel injection, but i dont see the advantage.

did fuel injection come on later model 292's, and if so why doesnt everyone use it? what kind of hp improvements can be expected from tbi or mpi over lets say a 500 or 600cfm edelbrock? I saw a tbi on ebay for a 250, he said it only got 14 miles to the gallon! wheres the advantage? fuel injection is supposed to get better mileage and deliver more hp and torque, I see that mileage is not better, what about power? plus they are way more work! I love fuel injection, but i dont see the advantage.

My antique digital cam has no mic - so no sound..

Tom - basically yes, a good fuel/ignition curve could be built on a chassis dyno for given engine combo and it would be close for other simular setups.

Once the set up is installed and the owner was comfortable with the basics they could fine tune the fuel and ign map. Just save the orginal set up as a baseline.

This really depends on the tune up - if its poorly tuned and running rich then mileage will suffer. If you run a wide band O2 sensor and set megasquirt for auto tune then it will adjusted itself to a pre-determined A/F ratio.

efi-diy
What MegaSquirt you're using? Is it easy to install?
Have you learned how to install and tune it by yourself, I mean alone?
Thanks

I'm using the MegaSquirt (MS) v3.00 main board and the MSII processor.

I have been using MS on other projects for 5 years, but yes in the beguning I learned how to install and tune it by myself with some help from the MS online forums which were very crude at the time.

If you know how to use a digital multimeter to troubleshoot electical systems then MS is not hard to understand. It does involve some reading, however, now the MS community is almost 15,000 users strong so finding someone nearby who has installed a MS is not so hard anymore. Most folks are more than helpful at getting others running.

At last count that I asked there were over 25,000 MS boards shipped! Imagine how many parts we could have for our inline's if we had that kind of demand.

Update.

I have the 2nd build (beta) of boards in hand and will be building the beta build next week. SOme other folks from the MSEFI board have bought a couple of the beta versions to help out with the testing - I do have 2 beta boards left if someone from here wanted to participate in the beta testing.

Cost is US$57 shipped anywhere in the USA or Canada, this is for the bare board only. The parts for the basic assembly to allow the GM harness to plug in are about $25. Add the cost of a MS main board and a junkyard GM ECM - roughly $275 and you have a plug and play EFI solution.

What I have not mentioned yet is this: the board will very soon be able to control the 4L60E/4L80E transmissions in addition to doing fuel and spark control. The software for the transmission control is about 80% done.

The best thing is that everthing will be tuneable from a laptop - e.g. shift feel, shift points, and convertor lock up.

The boards will fit into a modified GM ECM case so the stock mounting backet should be able to be reused, simplifing the install.

Marc

Update.

A local rodder who has a '55 chevy 4door with a 350 in it changed from an Edlebrock 600 cfm 4 bbl carb to TBI from a '90 350 truck using Megasquirt as the controller and a wide band O2 sensor - he picked up 7 MPG! (from 16 to 23 - that like over 40%!) on the highway over the carb. He is using a 700R4 and in OD the TBI does a much better job of metering fuel than the carb can. The carb does not get enough signal at high load low RPM to meter fuel as well as EFI can.

I would like to try TBI but I am limited to 500cfm 2bbl carb throttle bore size. What size are the throttle bores on the 4.3 V6 and 350 TBI?

The 350 TBI flows 500 CFM @ 3" HG (the old 2 bbl rating). I think the throttle bores are 1 5/8" to 1 3/4" each - but I don't have one here to measure. The 454 ones are 2".

This is looking real good please advise when
the 4l80e i ready as want to fit this system
to my motor home c30 , millage shocking with
holly 350cfm judt will not go past gas stations

How would a TBI setup react to boost?

Well there would be a couple of considerations:

1) you would need to boost reference the pressure regulator which is typically built into the TBI unit.

2) TBI injectors typically run at 15 psi, depending on which pump you used it may need to be swapped for a port injecton type, as it may not have enough pressure capacity to keep up with the boost referenced regulator.

3) For mild boost applications it would most likely be fine, you would want to ensure the injectors are big enough to feed the motor.

The '84/85 Ford 302 used a CFI (ford's TBI) that actually used regular port type injectors so for a boost application this may be a better choice as there is a much wider injector selection out there. Also this unit will bolt on where a motorcraft 2bbl carb will fit.

M.

The link below is from the MS site where I posted a few pix of the beta version MS to GM TBI adapter - this time fully built and enclosed in its case.
http://www.msefi.com/viewtopic.php?p=172661#172661

I'm also planning a "mini version" that does only does the GM to MS harness conversion and it a lot easier to build - add like 6 parts on the board and your ready to plug it in.

M.

I am planning on building a Ford 300 and would like to use a Mega Squirt. The engine has the stock pointless dist. And I see you used a aftermarket 4barrel intake on the 292, so I guess the 300 would't be any different. Would you use the same TBI? I have looked at the MegaSquirt site and their forum and its a little like taking a drink from a firehose. Does anyone have a list of parts and what wire harness to use. This engine is going in a 41 Chev.P/U so I don't have any stock injection harness.

Sounds like a plan, but I still don't know which MegaSquirt I need. I was hoping they had a catalog with some instructions. And I think but don't know that I would need a Ford harness if I use the Ford injection.

If your engine is 100% stock including the exhaust system then get a complete late model Ford EFI from a 300 six and bolt it in and call it done. If you are going to tweak the engine then use megasquirt.

Why ? Ford spent 100's of hours getting the calibration dialed in, if the engine is bone stock then use the factory electronics. On ht eother hand if you want to tune it then use MS.

If you are going to use megasquirt then cosider using:

MS 3.00 mainboard
MS2 plug in processor.
then get a MS to EEC IV adapter board from Scott : http://megaefi.com/

This make for a plugin - minimal wiring converion.

If I supplied at no charge the GM adapter boards pre-built for 2 people - who wants to try TBI?

You need to supply the vehicle equipped with a 12V 80A (min.) CS series alternator, the GM harness, TBI and fuel system. Also you would need to supply a megasquirt V3.00 main board and the megasquirt MS2 plugin - all of which can be bought pre-built if you so wish. In order to bolt the TBI on you need a 4bbl intake and a holley TBI to 4bbl adapter plate. To start you can retain your existing ign. system - although then MS would not control the timing. Later you can switch to the '81 calf. HEI dist. and do timing control.

What I ask in return is that you make a commitment to have the conversion done within 4 weeks.

how do you go about setting up a 75 inline 250 to fuel injected?

Kind of hard to answer your question as its really wide open.

To start look at the pix. listed in the first post above. I used a Holley TBI instead of a GM one but the idea is the same.

Then vist a local U pull it junk yard and look at a '88 to 92 GM truck how the TBI is installed and how the fuel system works. There are 2 fuel lines - supply and return. Big one is the supply - small is the return.

So bascially you bolt the TBI to the Holley adatper plate which in turn is bolted to a 4bbl intake mainifold installed on the engine. Hookup the throttle linkage (cable types work best).

You then install the supply and return line to the fuel tank along with the TBI electric fuel pump.

Then you install the harness from the donor vehicle and the ECM. Wire in the harness ( yes you will need the a wiring diagram from the donor vehicle) to your existing harness at the ign switch and main power feeds using fuses where needed to duplicate the ones from the donor vehicle.

Hope this gets you pointed in the right direction.

Thanks-that answered my question too!

well for now i'm stickin with my carb (tryin to find a 2bbl) but i may try out fuel injected after the rebuild, maybe even incorporate it with the adding of a turbo. i wish there was someone around that had a straight six shop that i could watch some work get done, i'm more of the hands on type (go figure).

So basically to go efi i need a donor late 80's earli 90's GM and run supply, return and install ecu? Would this application interfere with adding a Dakota Digital Dash?

Brad,

Your close enough for a road trip here - come on up and we can do the converion in a day... if you have a digital video cam - we'll record how easy it really is and post it so the rest of the inliners can see.....

Not that I can think of.

any measure of what this fuel injected setup would be that you use, combined with a turbo on a 250 block with an aftermarket exhaust system? kind of broad, but curious to know if this setup would be pushing 350+ horses with reasonable mpg.

EFI when tuned provides accurate fuel metering over the entire operating range. At low power settings you can set the A/F ratio in the 15-16:1 range for economy and at WOT set it for what the engine wants to make best power - usually somewhere in the 11.8 to 12.5:1 range.

As far as power that the engine would make - well thats depends how much air your moving through the engine - not directly dependant on the EFI system.

For now I can only talk about my Syclone.4.3/262 CI V-6
Factory ECU,but has a switchable boost & timeing settings.
It dynoed @ 386 HP & 550 Ft lbs torque @ the wheels.
Gas MPG is 18-19 MPG & it runs low 12's in the 1/4.
You need a muti port fuel injection, not a throttle body injection.

MBHD

that would be awesome if you guys actually made a step by step video of the F.I. swap using megasquirt, I would love to see something like that!

Since my 292 is now in Iowa... whats needed is someone who wants to do the conversion. If the fuel system is pre-installed the electrical portion is a couple of hours work. Also they would need to take a road trip to Calgary so we can do the work here. If we need something I know where to get it here - in a new localation that could turn into hours.