[worthidlj]

Hi All,

I'm considering converting a vintage car to efi with a speeduino base ECU.
However, I'm unsure if the dynamo can provide enough amps compared to an alternator.
What power requirements are needed to run a sequential injection/ignition 4-cylinder speeduino ECU and does the collective knowledge believe a dynamo can handle this?

Thanks for your time.
Dave

[jonbill]

I think fuel pump, injectors and coils and speeduino may take 15 amps.
I read dynamos can be as low as 8 amps....

[JHolland]

Is it 12V negative earth?
Injectors will be around 1A each, if your dc is 80% max. then that is 3.2A total
What coils would you be running, what dwell times and up to what RPM?
The fuel pump draw will depend on how big it is how much fuel will you need in gph or lph?

[PSIG]

+1, you need to provide the rated output, at both idle and peak, with the rpm. Some ratings are shaft rpm, and pulley diameters alter the crank > shaft rpm, so take that into consideration. Concern could be at either end of the range, depending on how it outputs.

+1, the system is designed for 10 to 16V negative ground, and verify you can get that for the system, either direct or converted (step-up if 6V). Most old cars have 12V conversion instructions online.

+1, the fuel pump can be lower-amp, such as 30mm 35LPH @3-bar or higher bike pumps, typically using 1.5 to 3A. Those will support over 100hp as-is. Similar setups with a surge tank and regulator are available as a single-solution (random example). I have a cheap online 30mm/35L here I'll test amps under pressure when I get more test fluid.

+1, distributor ignition is 5A or less for high-energy, and multiply by the fractional duty cycle. Not a big load, average, e.g., 5A at 600 rpm 4-cyl idle is 0.27A average.

+1, for injectors, as if the concern is at idle gen output, the battery stabilizes and the duty cycle is also low for average draw. Older-technology engines tend to see little benefit from sequential, so consider TBI or paired default as a first option.

+1, You can see where this is going, and it circles back to what the gen will do, and targets you need to stay under. Have fun!

[worthidlj]

Thanks for the responses.

@jonbill - I thought that would be the case. The dynamo I was looking at using (Lucas C35M) would only give around 10amps when converted to 12v -ve earth. Might look into a dynamator or just plain alternator and lose the aesthetic.
I'm researching to find safe output for a 12v converted dynamo as I have seen some solid state regulators with a 22amp which might help run the efi and lights!

@JHolland - The car will be built as 12v -ve eart as it is currently a pile of bits! I'm looking at Yaris smart coils with a max [Hard Limit] RPM of 5200RPM (The engine is a 3Brg Austin 7 750cc engine which don't like many revs). I'd probably get away with a bike fuel pump so hopefully won't draw too many amps.

@PSIG The dynamo is gear driven and can be converted to a 2brush 12v -ve earth but trying to confirm the safe amp output from someone who rebuilds the dynamos.
I'd be lucky to get 40HP from this motor, even in supercharged form; he he! So I think the fuel pump shouldn't be too draining.
I'm thinking of smart coils so would that affect amp usage much?
I was considering sequential more as a challenge but can change that if it's too much,

Thanks to you all and will feedback when I have more info.

Cheers

[worthidlj]

Update

I've heard back from the company that restores/converts dynamos and the max amp rating is 12amps.

This will be too low as I still want to be able to use lights and a cigarette lighter (for satnav. etc) so will look at alternator options that have been done on these engines before.

Cheers,
worthidlj

[PSIG]

I'm thinking of smart coils so would that affect amp usage much?

No change. More important is your choice of coil to minimize amp draw yet obtain a solid spark for your needs. COP coils are capable, but tend to be high-amp to get the same power from their small size. My first hunch is to go with CNP with much more power capability, but drive it softly for lower amps. Better spark energy with less current concept.

I was considering sequential more as a challenge but can change that if it's too much

No problem with sequential, but tends to be less impactful with these older and smaller engines. Not much if any gain for how they are typically used. Yours may need something else. Sure, go for it, but two factors for me are simplicity to get it on its feet and performing, and if the system is appropriate for the goals. Minimal conversion will immediately show where it is sufficient, and where it is lacking (if it is), or how you may want to tweak it. This avoids guessing and 'over-building' to cover any conceivable issue, when you only need to cover those that are real. Be clear in your goals as they will affect every step of the process and the choices you make.

I will be following your thread, as I have a 1931(?) Austin 7 Saloon project next year. While tiny compared to your 40hp monster , it's an exciting challenge for me to take a car approaching 100 years old for conversion to EFI and controlled ignition.

As the owner wants the benefits of the control, mostly for ease and reliability of operation with extended time to overhaul; he also wants some level of original appearance. As few know what an Austin 4-banger looks like, I might shroud port injectors under the intake, but more likely fab a simple down-throat TBI on the original carb for first analysis and what is indicated by data for best operation.

I've only seen the car for 30 seconds, so it's all theory at this point. Anyway, keep going, and let us know how you fare!



[EDIT] I recall some guy in Europe several years ago installed a system in a 6V negative-ground car as a separate electrical, using a 12V battery to power it all. No car mods. I don't know many specifics, but he claimed about 4-hours run time between charges, which was enough for his parades and in-town cruising before recharging. Just throwing options to rattle around your brain as seeds for new concepts and approaches.

[worthidlj]

Thanks again for the feedback PSIG.

I'd like to try and keep a 'neater' arrangement and will aim for COP, if not I would probably go to a standard coil arrangement.

You make a good point about being clear in my goals; I think I know how i want to progress; just the usual case of getting enough time, money and skills to do it now, haha!

40hp will be a dream TBH, just from surfing the Austin Seven forums it appears to be achievable on carbs so hopefully efi would make it a bit more consistent.

I'm more likely to follow what you do as I am way off starting this and currently getting parts and information at present.

Just be aware the the Austin 7 engine has Siamese inlet ports on the same side of the block as the exhaust ports (a-la Austin A-Series) so may be better to go with your though of TBI on the original carb; though it is believed Lotus founder Colin Chapman developed an intake manifold that has 'blades' that protruded into the block ports to make them separate.
Also, it is a side valve engine with a compression ratio of around 6:1 so would defenitley be interesting to see how you find things.

That's interesting about using separate electrical systems, that would be even more of a head scratcher for me.
On new seeds I saw an offhand note that a conversion back in the day was to swap the standard dynamo for one from a VW beetle; though these are primarily of larger diameter research shows that a couple of Porsches had a Ø90 generator and there are kits available to swap the insides to a 12v 30a arrangement, so thinking could this be modified to fit in the original A7 C35 dynamo housing. Defenitley something for me to think about.

Cheers,
worthidlj

[PSIG]

Perhaps you have already searched, but there are some posts on Siamese ports here, chatting about fuel distribution, port dividers, etc. Let us know when you get to the point of moving on it, and we'll be here for the party.

[usatracy]

john deer 20 amp tractor dynamo, its what a lot of people have used. only weighs 2 lbs. John Deere Dynamo AM876052, AM877557, MIA10338