Want to put EFI on a 6 Cyl. What System to get?

[7991LXnSHO]

This is about my other car. Let’s call it an American Porsche.
I am replacing the stock 80 hp, Air Cooled, flat 6 motor with a 140+ hp much improved one that should have a bunch of torque where the automatic and looser torque convertor lives. (It will not be as fast as my 5.0, but it aleady feels like a nimble go-cart.) On each cylinder head, it has a single carb over a cast on intake log that feeds three cylinders.

The next step for this engine could be to shave off the Intake logs, and install two, three bbl carb packs on short runners over the intake ports. That will open up the top end a lot, but it will not help street drive ability and torque where I want it.

So the other option I am considering is to shave the logs, add six tube runners (And small injectors) that go up to a center plenum and a horizontal facing throttle body. Then I can use use the new electronic distributor in locked out advance trigger mode for a consistent signal and not mess with a trigger wheel. The cam is gear driven, so it will never have a loose coming chain.

At that point, so much for it being a simple classic car that just looks fast. I could also go to a center mounted 4bbl carb mount with six legs without making something new. I like the more stock look of the 87-88 lower profile log
Clamato (it will not let me put Camaro) style intakes like the one pictured, but the six spider legs will be not be wrapped under. They go out to stand on to the heads.

I will have the possibility for IAT, cylinder head temp, oil temp and pressure, but no water temp on this six cylinder.

Finally the Big question! What Mega Squirt system from what dealer do you reccomend, or should I go with a TBI system from Holley or someone else?
Thanks for your advice and experience for a Very not stock application!

 

[a91what]

If you are going this far why not do an ITB? The linkage will be interesting to figure out though.
Also have the option of running a TB on each log with a tube between the logs for equalizing.
Imo I would run nothing less than an ms3, i would use a goldbox or prebuilt ms3x.
On a budget even a simple microsquirt will do the job just fine.
Even the micro could run this build in semi sequential, if the distributor can be easily converted to CAS (it may be possible with the guts in it now) LS coilpacks in wasted spark will be possible.

Basically any of the ms systems will be able to do what you want, however if you plan on the possibility of further upgrades in the future do not limit yourself.

I suppose I should ask what kind of budget constraints do you have for the build?

 

[7991LXnSHO]

Thanks for entertaining my bench build exploration!
I am starting from a point of a wide range of electric and electronic knowledge, a workable knowledge of stock EFI, and no hands on experience in aftermarket EFI. I want something that runs well without being extravagant. This engine is not built for forced induction, and although it should stand up to o Cassio all 7k RPM, that’s not where I want the power band to be. How much $$$ that will be is part of what I am here to learn. There are more knowledgeable and experienced EFI people here than in the resto and keep it running groups for the car.

I have seen a some different EFI conversions on this flat 6. The most complete kit has an older V-6 computer and TB adapted, and I think a better system should be available by now.

Three motorcycle throttle bodies per side looks cool, (is that ITB - individual throttle bodies?) but I want the extra torque from long runners, and I would prefer the injectors to be nearer the intake port than with a central TBI system. The center mount carb conversions have some part throttle drive ability issues. I assume is from fuel puddling, and they end up getting tuned out with more fuel. that’s not great for mileage or the air fuel ratio.

So unless I end up with icing problems, the cool air flowing over a center plenum on the way to the center cooling fan will not be a bad thing. (Pics of two cool ones included.)
I will check for sure with the distributor maker for trigger signal type. I know it is a feature he advertises with the electronic ignition distributor.
Do you think the systems mentioned would run on oil temp rather than water temp?
Thanks!

 

[a91what]

The megasquirt system is designed to be usable with an air cooled engine. If you decide to use the ITB (independent throttle body) the rpm range can be tuned by adding length go the runners, the trumpet above the throttle can be made longer or shorter to achieve this.
If you decide to make your own manifold I suggest port injection 100% of the time.
Some flanges tubing bent into 180* mandrel to a common plenum and a single tb. In an ideal world the injectors would be placed to fire directly at the valve but that's not a huge necessary as long as we get fuel suspension.
You tell me what you have available to you and I can tell you how to make it work with an MS.

 

[a91what]

One more thought, the gm spider injector system would work well due to your unique intake challenges.

 

[7991LXnSHO]

Awesome!!! I will get the rest of the resto mod done, and start digging into this now. It will run with carbs for a start, but then the power restriction after major head work is the intake. I can use the distraction from waiting for others to plan this cool step. I am adding AC and a nice stereo with some tasteful body mods, so stock is not an issue. I’ll be back!