homebrewed electronic fuel injection photo journal

Megasquirt is huge in the VW community. If you get jammed up you might want to dig around those forums for answers.

 

Cool thread and project!

I'm also going to use a MegaSquirt-I unit that my dad bought several years ago for another project, but never used. The inputs are vacuum to the internal (on-board) MAP sensor, tach signal (RPM), intake air temp, coolant temp, and throttle position sensor. It also uses a standard non-heated Bosch 02 sensor for closed loop operation. From reading the instructions it appears to be quite easy to tune.

The intake is built out of aluminum tube and I'm going to use Ford 71mm throttle bodies from the 4.6L V8. I got these at pull-a-part mostly off 94- T-Birds. Don't know how it's going ot work yet, but I'll let you know when we get it running. Oh, the engine is a 500 Caddy in my Model A tudor cdan.

 

BeefStew: actually, I am not having the computer control the timing. I will be using a stock points distributer with vac. adv. and with Pertronics(although you could still use points if you wanted). The computer gets RPM signal from the negative of the coil and that tells it how often to open the injectors.

A megasquirt computer is pretty basic. you send a few inputs to the computer and it calculates an output. there are 6 sensors(inputs) i am using. MAP(wich is the manifold pressure), coolant temp, incoming air temp, RPM, throttle position, and 02 sensor. the output is the signal to the fuel injectors. With these inputs, the computer calculates how often to open the injectors and how long to keep them open.

WCRiot thanks for your offer! it wasn't somuch the tuning but setting up the linkage in a way that they could be tuned. some way down the road ITB's might be an option.
Irish that is wicked cool! definately keep us updated on that.

 

Thanks man! Will do and I'll be following to see how yours works. Yeah the one I have doesn't control the timing either, just the injectors.

 

Glad to see some more megasquirt users. I am not sure about mine just yet still tuning.



I built mine also threads on here.

 

thats a clean setup. thanks for posting it. i finally got to a point on the wiring where i could test the system, but unfortunately my manifold kinda sucks. i filled the coolant system with water and it leaked into the valley and into the crankcase, something i was afraid of. the angle of the flange doesnt seem to seat against the head. i guess i could double up intake gaskets, but i found a knock-off moon style intake on ebay for cheap. it should be shipping soon, so hopefully it'll get here before finals.

 

new manifold

 

Man you got lucky finding that one!! LOL

LOOKING GOOD MAN! Keep it up!!

 

Question, how do you select the right size injectors for your setup?

I've been reading up on megasquirt and that part just eludes me.. I'm planning a blown straight 8 with siamesed intake ports, throttle body is in front of the blower (Eaton M90) injectors on the intake ports.

So do I use 4 large or 8 small injectors? How do I decide and how do I calculate how big the injectors should be?

The engine is a 248ci Buick, planning to underdrive the compressor to around 3 lbs.

 

Fuel useage is a function of horsepower. The typical brake specific fuel consumption for a naturally aspirated motor is a .5 so that's a half pound of fuel per horsepower. If you plan on making 200 hp you need 100 lbs of fuel. You then divide this fuel amount by the number of injectors you're going to use times your maximum duty cycle. So, using 8 injectors at say 80% dc means you need 15 lbs/hr fuel injectors or if you use 4 injectors you need 31 lbs/hr fuel injectors. So that covers naturally aspirated.

Because you're running such a low amount of boost you could probably stick with .5 or go as high as .6 or .65 bsfc. You might have problems with those siamesed intake ports though. We've been fighting a rich-lean condition on our Model B flathead race motor. We're about to go with EFI to hopefully fix the problem.

 

Thanks, great info.. kind of stuck with the siamesed ports, not easy to redesign that head or have a custom camshaft ground to switch the intake and exhaust ports.

Alternative is to run the blower wet and put the injectors before the blower, hopefully cooling down the blower and getting better fuel/air mix consistency that should hopefully negate the siamesed port effect.

I did blend the intake ports a little bit, just removing the casting flash and ridges and flow tested it, it's pretty well balanced out now.

I may initially build it with a carb before the blower, just to get it running and then upgrade to EFI and electronic ignition controlled by megasquirt.

 

I understand being stuck with siamesed ports. I've seen some guys fill in the block of their Model B and cut four intake ports. Lots of work... too much if you ask me.

The problem with siamesed ports is the 360 degree overlap between the intake valve opening sequence. Basically, on a constant flow system (carb or mechanical fuel injection) fuel is being feed into the intake port while both valves are closed. Then the first vale in the sequence opens and it gets a ton of fuel and then it closes and the second valve opens and it gets hardly any. So the first cylinder to get the fuel charge runs very rich and the second cylinder runs very lean.

This problem might only exist in a four banger with a 180 degree crankshaft and front/back/front/back firing order. I'd have to know what the firing order is for your motor to see if you'd have the same problem.

Anyways, what we're doing is using a fully sequential efi system that is perfectly timed with the opening of the intake valves. This will hopefully feed the same amount of fuel to each cylinder and fix the rich/lean problem we've been having for ever. We run a turbo and the extra heat and pressure makes the problem even worse.

 

Did you decide upon throttle bodies? If not check out the units on the 5.3 liter Jag V12s.

 

i've made some more progress. here is the start of the intake and the finished fuel rail. i've also plumbed the fuel line to the tank and put in and inline filter and pump.

 

Pretty work!

Is this your first megasquirt project? How steep is the learning curve? I've been looking over their website and the gears are now spinning in my head for a future project.

 

Do those nozzles spray straight down, against the floor of the port ?

 

Mega squirt and turbos????Sounds like tuner talk.

 

Hot rodding has progressed from flatheads to valve in head engines, from single barrel carbs to four barrels, and from manual trans to OD automatics, so I guess it's all relative in the grand scheme of things. That's what I like about this hobby you get to pick your poision.

 

What makes it a hot-rod? he did it HISSELF! Nobody makes what you need? Build it your self! Sounds like the definition of what "traditional" started out as.

 

Now this is a class act!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

the injectors are about 30 degrees from being perpendicular to the runner. you want them to be as parallel to the flow as possible, but this allowed me to simply use one rail as opposed to the usual two banks, which made it easier to fab. if it doesn't work, i can always change it.

this is indeed my first megasquirt, but i would definitely say go for it! there is alot of information to take in, but if you are patient and diligent, it would be worth it. read the megamanual. it's like 56 pages but it is totally step-by-step and shows you how to double check your work. another thing that was really helpful was the stimulator. it's really like a big model kit!
another thing to think about is cost. although this wasn't as cheap as a new holley 600 and intake, it's not too bad. i have about $900 into this so far, and thats using alot of new parts and buying stuff i ended up not using.

thank guys! i can't wait to put on sum honda graphix and sum underglow! jk.

 

Well why is it then when someone post pictures on here of a car that is not(TRADITIONAL)every one gets butt hurt but when you talk about stuff that the tuners use it's ok??Hell lets put mass air on it and some apc accessories.I admit that I don't ignore advances in technologies but seems like every one on hamb gets all bent out of shape if you use radials or disk brakes(which by the way I don't use any of these but I have in the past) every one goes ape???

 

I hear you man, I'm trying to do it with my own style. I definitely want to stay away from any kind of "accessories" or blingbling. the way I figured was if I had a grand, I could buy a brand new duel-quad or tripple-duece setup, OR I could build something on my own, have some fun, and learn some stuff.

 

I got it running!!! I'll post some pics or video soon if anyone is interested. it's such an uplifting feeling knowing that all the hard stuff is done. i just have to mount the tank, throttle linkage and bleed the brakes. crusing next weekend hopefully!

 

Good Job... It is a very satisifying thing to get something that appears very complicated up and running. (I had the same feeling when I got my LS1 all together and running).. Keep up all the good work and give us pictures....

 

Excellent. Would love to check out the video.

 

Everyone has their opinion and is free to voice it. That's one of the things that makes the U.S.A. a wonderfull place. There's no harm in disagreeing with something. He's working on a good old piece of American iron, it's not a Honda or Nissan.
There are a lot of folks on here running radials and disc brakes. Safety is a good thing especially when you have to deal with some of the drivers on the road today. Relax my friend, life is too short to stress over the little things.

 

This is the info from The Ford site about injector capacity.
The first column is n/a, the second is supercharged.

Inj Flow Rate (@ 40 psid) Naturally Aspirated hp (@ 0.50) Forced-Induction hp (@ 0.65)
19 lb/hr 258 hp @ 85% Duty Cycle 199 hp @ 85% Duty Cycle
24 lb/hr 326 hp @ 85% Duty Cycle 251 hp @ 85% Duty Cycle
30 lb/hr 408 hp @ 85% Duty Cycle 314 hp @ 85% Duty Cycle
32 lb/hr 435 hp @ 85% Duty Cycle 335 hp @ 85% Duty Cycle
39 lb/hr 530 hp @ 85% Duty Cycle 408 hp @ 85% Duty Cycle
42 lb/hr 571 hp @ 85% Duty Cycle 439 hp @ 85% Duty Cycle
47 lb/hr 639 hp @ 85% Duty Cycle 492 hp @ 85% Duty Cycle
60 lb/hr 816 hp @ 85% Duty Cycle 628 hp @ 85% Duty Cycle

 

I did this on a 4 cylinder project. I think 71mm tb's will be ever so large, you may have problems just off idle. I used CBR 929 fireblade tb's on my project and I couldnt get rid of the stumble and low spot. I switched to F4i throttles which were 38mm and problem solved. The problem with bike throttles though is the short throw, 1/4 turn and they are WOT. I fixed it by extending the throttle arm, but that was exciting at the lights for a while trying to feather it enough to get moving.

ITB EFI sounds absolutely astounding at WOT. The noises my motor made were like an angry and powerful animal. Well, it was a 2 liter 4 so maybe like an angry lamb. No it wasnt a honda. Yes compiled the assembly code myself to run E85.


Cool project. I am a huge fan of people who learn by doing. Good joerb!

 

wfo guy, thanks for that info, that'll be useful when it gets turbocharged. joedoh: I am wondering that as well, so we shall see. this is the final setup of the intake minus the linkage, which i'm building right now. video soon!