DIY Beetle Fuel injection conversion

[4agedub]

I'm in the process of making up a kit to cost effectively convert any type 1 air cooled vw engine to EFI without having to cut or physically modify anything.

Here's the basic idea...
Use the original vw intake manifold, bolt on a throttle body with internal injector, use the original 6mm fuel line and a Mexican beetle fuel pump... then you end up with something like this

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Here's the parts list of what is needed:
-Throttle body
-440cc injector
-Fuel rail
-Throttle position sensor
-Intake manifold adapter
-Air filter adapter
-Beetle specific linkage
-2x return springs
-Hall effect distributor (eg combi 2.1) I'm still working on this part to get a cheaper option
-Mexican beetle fuel pump in surge tank
-Fuel pressure regulator
-3x 8mm to 6mm hose adapters
-2m 6mm high pressure hose
-3m 8mm high pressure hose
-16 Hose clamps
-Electronic ignition coil with plug
-ECU of your choice

There is no return fuel line due to the fuel setup, so less modification.

Here's the intake manifold adapter. It needs to be 8mm thick and uses 4x 6mm Allan caps to hold the throttle body to the adapter and 2x 6mm counter sunk Allan caps with lock nuts to hold the whole assembly on the manifold.

beetle dice throttle adaptor.jpg

The linkage can be cut from stainless steel and then welded together. The linkage then uses the std beetle barrel nut for the accelerator cable.

dice linkage.jpg

I unfortunately did not take any photos while assembling the first kit, but will take detailed notes on the next one.

[vader]

Interesting...
Now you will have to do a full road report. So if I have it correct, which I seldom do, this setup will work for both TP & SP heads? Please can you give me somemore detailed info on..
1 Position of the injectors. Pro's & Con's.
2 Can the injectors be fitted into the inlet manifold of a TP head running a single throttle body?
3 How many injectors are there in this setup? 1,2 3, or 4?
4 What is the projected cost for this setup?

Good work as usual.

[Loopy]

Looks good! Would this be scalable, eg throttle body per cylinder or per side?

[riaanj]

Cool sh!t man..
Some questions: is this only for 1600's or will it work on the smaller (or bigger) motors? will the injector size and/or throttle body size change for different size motors? what size is the throttle body you used on the car in the pics (I assume it's a 1600)?

Cool conversion, like how it looks almost stock!

[YvaneS]

That is awesome!
You are really filling a gap in the market!

Keep us posted!

[4agedub]

The idea with the kit is to make is as cheap as possible, thus it has only got one injector and one throttle body. Going to twin throttles or even to four throttles cost more. The four throttle kit has been around for a while now.... but be prepared to spend over R15k on a four throttle system.

@Vader. You can go four injectors, but yet again this costs more. The kit is not really aimed at the performance market, but more for the guys who are having issues with the solex carburetor and need a cheap option to replace it. The downfall of the single injector is that the throttle response is not as quick as with four injectors.... but it's about the same as the carb at the end of the day.

Cost.... I'm still working on that part.

@Riaanj. This will work on any size engine, but at the end of the day is not really aimed at the performance market. If you want ultimate performance go four throttle.... if you have a 1776 or 1835cc engine that you use on the road, this will be perfect.

For turbo charging this setup will work awesome, simply bolt on a turbo onto your stock engine... run 0.3 bar boost and tune the fueling and timing to perfection.

[4agedub]

I have now tuned the beetle on two brands on ECU's to see how they compare...

The test involved checking:
-Cold start
-Cold throttle response
-Hot start
-Drive ability
-Throttle response
-Max kw on the wheels

I have not been able to check fuel economy yet. Right now I'm not going to reveal which ecu's I tried.

Lets call them ecu 1 and ecu 2. The rating is out of 10.

ECU 1
-Cold start 9
-Cold throttle response 7
-Hot start 9
-Drive ability 8
-Throttle response 7
-Max kw on the wheels: Same kw reading 38kw

ECU 2
-Cold start 6
-Cold throttle response 5
-Hot start 9
-Drive ability 9
-Throttle response 8
-Max kw on the wheels: Same kw reading 38kw

Now, this is not a conclusive test yet as some of the factors might simply be my tuning knowledge.

[riaanj]

Cool, so should I keep the 1600 motor in the car, it will be a perfect setup..
I see ECU 1 scores just a bit better than ECU 2 overall, are you using Gotech?

[Bratjie]

For turbo charging this setup will work awesome, simply bolt on a turbo onto your stock engine... run 0.3 bar boost and tune the fueling and timing to perfection.

Hi 4age, I am in the proccess of fitting my wbx turbo motor to the beetle, I will be running n/a fr a few days just to check out the engine, then I will fit the turbo and Gotech, would it work if I replace the Dellorto with an inj system like this? I plan to run max 14- 18 psi boost.

[flatfourfan]

Nice write up and a good idea...I'd be interested to see what type of economy you'd get as well as what unit has stability idle control, (for days when wipers, radio and high beams are on), would that effect idling, (searching or bumpy idle?) any chance that you could test that?

The ECU's that you're using, I take it that they are aftermarket?

Once again.........good stuff.

[Qkickslvr]

Hi 4agedub.

Don't mean to cause any trouble. I've seen something similar that spitronics sell for the Nissan 1400"s. single injector setup. Seems they getting about 10k/l if I'm not mistaken.


Good luck with the project I'm sure it could be a winner.

[Dawie]

I would imagine Fuel efficiency would largely depend on having a good map in the software. As in spending some time with the prototype on the dyno, wideband afr sensor connected, and some road testing. But sounds like you are doing this.

Are you sensing MAF or MAP (manifold air pressure)? Is it doing ignition timing as well?
Because of the firing order maybe setting the upstream injector to do 4 injections per full cycle/720 degs for even distribution between left and right side.

Also think an exhaust that retains manifold heating would make a difference.

[4agedub]

@Bratjie
For a high boost application like yours I would rather go for a four injector setup to make sure each cylinder received the equal amount of fuel. You can then keep the carb on and use it as a throttle body.

@Flatfourfan
There is no idle control on the throttle body. A idle valve can be added, but obviously it adds onto the price. You can use a Golf digifant idle valve. As it is now, the engine starts first time and idles at about 600rpm when cold. The warm idle is at about 900rpm.When hot it does not seem like the voltage drain affects it a lot.... the idling drops by about 100rpm with the headlights on bright. Both the ecu's are after market

@Qkickslvr
I'm using the same throttle body as Spitronics. It's actually made by Dave Ingle in cape town. As for fuel economy on the beetle, I have not had a chance to do proper mileage yet. The Spitronics nissan kit does not use a fuel pressure regulator, the fuel pressure is voltage regulated by the ecu. On my setup there is a fuel pressure regulator, but no return line from the back. Most modern cars run like that. Kits like these have been around for ages, but none have been sorted properly specifically for a VW beetle application.

@Dawie
I am using a map sensor for the fuel map and TPS for the accelerator pump. The injector fires every 90' crankshaft due to the injector placement and that there is only a single injector. At the end of the day four injectors should be a little better on fuel economy, but I would not run it full sequential.... the beetle engine needs cooling on the intake valves. The manifold heating has been disconnected on my engine, the fuel cools the intake and reduces intake temperature which also makes a difference on the fuel economy and performance.

[flatfourfan]

good replies...........this seems like a well researched idea.......kudos to you.

[riaanj]

Now we're just waiting for the pricing..