Some months ago I embarked on installing a Toyota SC12 to my Ea81. It was a steep learning curve for me as there was limited information available. I have a Australian Panther trike.
Here in Australia if it had been done I couldnt find an owner that did it and had to rely on a VW site started up by a guy I became friends with - Joel, who'd installed one on a VW beetle.
The SC12 and SC14 are similar chargers apart from the 14 being 50mm longer. They can be mounted on angles but the dip stick on the 12 would need to be plugged and oil levels couldnt be determined without raising them vertically. The Ea81 being the flat configuration allows room for the Sc to be mounted between the alternator and the centre intake on the manifold.
At this point I'd like to mention that these chargers are somewhat ancient now, the dino's of the charger world. If you have the pennies and want to keep the Ea81 for your own reasons and not go EJ then I'd seek out a modern charger. A Sprintex Australian made one is ideal and used on other vehicles like Harley and Mini's. There are others. Do your research. You may only need to make you own manifolds inlet/outlet pieces so a bare SC might be much cheaper than you think.
Draw through or blow through?
Draw through is when you mount the charger so that a fuel/air mixture is drawn through the charger, pressurised and sent down the manifold to the chambers. This is the simplest method of installing a SC. The pros'- simple install, carbie isnt pressurised. Con's- poor economy, longitivity of SC internals unknown due to fuel travelling through it, SC longitivity unknown due to being used 100% of the time.
Blow through is when the sC is mounted in such a way that it creates boost before the carbie thereby pressurising the carbie internals. This means you have to rebuild the carbie to cope with that. Filled flaot chamber for example so it doesnt implode. There are carbie manufactuers that can sell you one suitable if you prefer. The pro's- the SC can be clutched and used with an on/off switch this could be complex but will prove to be much more economical and will delay wear of the unit, the Sc is used in its conventional manner, The con's- mounting may be more difficult.
I dont know an aweful lot about Fuel Injection. I have embarked on a SPFI conversion and may not install a supercharger to it.
I chose draw through. In the end the system was dynoed. Pre install the EA81 had done around 400,000kms and at 320,000 kms had had new rings and bearings by the previous owner. The engine had 74hp at the fly and 59hp at the rear wheels. It is mated toa 3 speed type 3 VW automatic. After Sc install the figures were 100hp at the fly and 82 hp at the rear wheels.
The boost was 4-5 psi achieved from a driver pulley of 135mm and the standard clutch pully of 120mm. The clutch pulley was drilled and bolted up for a solid unit. A 5 ribbed belt was used. I purchased my sC12 without intake and exit manifolds. Besides as my charger was going to be moutned close tot he intake those manifolds were of no use. If you are going to mount the Sc far away from the intake you might want to consider buying a SC12 with those standard units.
I would highly recommend a turbo blow off valve in the custom manifold between the Sc and the intake.
On the draw through you wont need the vacuum to be hooked up to it...it is used solely for when the engine backfires- releasing prssure from blowing your Sc to bits. It has worked several times on my set up. You can plumb the blow off back to your air filter body.
Manifolds. Definately where the work is. I purchased a Datsun 1600 twin carb manifold on ebay and cut it in two.
(See how the intakes on this manifold angle towards the middle)Then I had to shorten it for my application. I needed to make an adapter plate to mate the Dellorto 40DHLA carbie to to SC. Use 5mm steel plate not under that. You dont want air leaks. This manifold also has all vacuum controls like my auto kick down. One the other side I had water injection for a time. More on that later.
The manifold from the sC to the intake was more difficult and had to be hand made from scratch. I made up a plate to fit the SC exit again 5mm thick then a piece of 50x100mm square tube (I mounted the blow off valve here). Then a vertical 75mm pipe to another plate (this time 10mm thick) that is bolted to the intake. In both manifold I used 3mm nitrile rubebr for sealing and works well.
Prior to manifold fabrication though is the need to mount your SC. I made up my own mount and used an idle pully from a wrecker (junk yard for US) and you need to take your time lining up the pulleys. Make sure the belt is really tight.
I made up a frame above the SC to secure it to the ea81 manifold.
I mounted a switch to the ea81 manifold. This switch meant that as soon as there was boost it would switch on the water injection. I installed the water injection in a vain attempt to obtain better economy. It made no difference. My set up was using one litre of water every 10 minutes of boost. A 2.3 litre water container (windscreen washer unit) would easily last a tank of fuel. My WI unit wa s a snow performance unit and worked ok. But I suggest WI is for higher boosted engines.
5psi has made the engine transform. It is very torquey and pulls uphills easily. an example. (in MPH). A hill near my home town is steep and with the VW 1916cc twin carb engine I would climb it at 35mph in 2nd gear (auto). In the NA Ea81 at 45mph in 2nd gear. In the SC12 EA81 draw through it would power up there at 70mph in top gear.
I think one big problem with these set ups with a carb is tuning. The jetting of the carbie wouldnt be ideal for every rev range. At certain revs my engine chuffs out a plume of black smoke. I have swapped jets both idel and main to limit this symptom but cant entirely.
Overall I'm not happy with its fuel usage. My trike only weighs 550 kgms or 950lbs. US gallon is different than Oz gallons/litre so to make this simple whatever you achieve form your vehicle in terms of fuel usage estimate about 1.5 times that once a draw through SC is installed. So add 50% to your fuel bill. In my neck of the woods I was achieving 27-34mpg now 18-19mpg. Regardless of how hard you put your foot down- it matters not!. Nor the fuel you use in my case 95 but have tried others. I'm goign SPFI for that reason. Hoping with a rebuilt Ea81 with matched cam and rebore etc will get around 90hp in between the Ea81 NA and the SC system but with 30-36mpg.
The dyno readout before and after.
This report was meant to be a guideline and you can add your views and experiences. I'm no mechanic so its just my opinions based on building the system and living with it.