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Supercharging your ea81 pro's and con's


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14 replies to this topic

#1 tweety

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Posted 25 June 2013 - 11:06 PM

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.

 

 

 

 

 

 

 

 



#2 CarpeNoctem

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Posted 25 June 2013 - 11:33 PM

I was thinking of doing this using it accessory mounted (like an alt or ac) but this would be for a TBI unit. plumbed through and intercooler afterward. because they are meant for a magnetic clutch just get a v belt clutch and start fabbing the inlet and outlet manifolds and you can even time it by using a small amount of circuitry tied into the tps. I would likely run a non clutched pulley though.  Remember these do need their own oil and it has to be changed regularly. 

 

sc12 superchargers in america can be found in mr2 toyotas. but their is a better source for the bigger SC14. toyota previa minivans (will say supercharged on back). typically less minivans get scavenged at yards while mr2 units go fast. go for the bigger higher displacement version that still allows you to run smaller pulleys for an even bigger level of boost. any good machining shop (not the auto version a real manufacturing one) can make you custom pullies if you bring an example and give he dimensions you need. helps for spacing one out if needed for belt alignment

 

 

my $0.02



#3 NorthWet

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Posted 26 June 2013 - 01:31 AM

Have you dealt with Dellortos or Weber DCOEs before?  What is the intake pulsations like between the SC and the Dellorto's venturis?  Jetting carburetors such as these can be tedious, especially if you mistake how the air flow rate at the venturi fluctuates.  IIRC, the emulsion tubes need to be selected with the pulsation in mind.  Also, from the pictures I can't tell if you are running anything beyond the airbox flange of the carburetor, such as an airbox or airhorns.  Having at least airhorns is important if the venturis are seeing strong pulsations, otherwise significant fuel can be lost to standoff.

 

(I used to run a pair of Weber 40DCOEs on my 71 Datsun 510 (nee Nissan Bluebird) with an L20B.  They turned out to be nothing but trouble for me, especially the brass floats that kept "sinking"... not a good thing when you park pointed down hill.  Did MUCH better with a Holley 390CFM 4-barrel.  Better driveability, better mileage, and no real loss in peak power.)

 

Oz still using Gallons Imperial?

 

Cheers!


Edited by NorthWet, 26 June 2013 - 01:32 AM.


#4 tweety

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Posted 26 June 2013 - 02:00 AM

Northwest I think our gallon is 4.55 litres and your gallon is 3.9 litres.

 

The pics you guys are seeing with the air filter are the old pics before I shortened the Nissan manifold.  I shortened ti to allow for air trumpets and a larger air filter box on the air filter housing. Now I just use air trumpets and socks for filters until I renew my spare engine and install SPFI.  As afar as flutuations and that is concerned its beyond my knowledge.  But I think the way to go is SPFI for simplicity. I have over the last week been laying out the sPFI loom and manifold TB and find it rather easy to figure out the conversion with the help of this site.

 

Then if one day I decide to supercharge it I would buy a twin screw Sprintex blower and install a clutch.  The SPFI might then need a second smaller injector for boost only. I dont know if the standard sPFI injection system would cater for the extra fuel the engine would demand with boost, even 5psi.

 

I will say that 7psi is likely the ideal.  It is the amount that doesnt demand water injection even an itnercooler IMO and iostn overstressing the engine. This of course can be achieved with a larger crank pulley or smaller charger pulley.  Those interested can find the formula on the itnernet.  I worked it all out and was spot on with my calculations. 

 

The manifold from the SC to the intake. inside it was made smooth with liquid weld. 

 

.

 

This was the filter box made form an electrical box.  later I discarded the box just to use the trumpets and socks

 

 

The top mount for the SC

 

 

Another shot of the Sc to intake manifold.

 

 

 

Oh yeh, I started to get blow by so I install a catch can.  Works good.  Not much oil is caught but if not in a catch can then it can pop your dip stick and exit there.

 

 

My previous car history with twin 40DCOE webers was on a Ford Escort twin cam (lotus powered).  Other than than I have little experience. I want to now drift away from carbies forever lol



#5 Crazyeights

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Posted 26 June 2013 - 09:04 AM

This is nice! Imagine this build with EA81T MPFI heads.  I think It would have to use stand alone fuel management though.



#6 ivans imports

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Posted 26 June 2013 - 10:18 AM

what pistons did you use ? nice setup why not turbo ? or mpi carbed super charger its like being at the drag race track lol does it lag when you stomp it wot ? is it soilid lifter engine or hydro I bet that machine with a ej2.2 turbo whould be crazy fast and the front wheel whould never touch the ground



#7 NorthWet

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Posted 26 June 2013 - 12:43 PM

This is nice! Imagine this build with EA81T MPFI heads.  I think It would have to use stand alone fuel management though.

I would imagine that the MPFI heads would not be worth the effort.  SPFI is still probably a better way to go, though, regardless, you may need a plenum before the MAF in order to dampen the pulses from the SC.



#8 tweety

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Posted 26 June 2013 - 07:29 PM

At this point guys I have no plans to install a supercharger to the SPFI unti about to go on.  The engine and indeed the engine that will replace this current engine next year are stock EA81.  Absolutely stock....no mods.

 

My spare engine will be fully reconditioned next year and I have no mods planned except rebore, raise the compression from 8.7 to the spec 9.5:1 that it should have either by SPFI pistons or head shave.

 

I admit that a EJ22 or 20 in the first place when I embarked on Subaru transplant would ahve been better.  But now that I've forked out for an adapter and exhaust then I cant see the justification of going EJ now.

 

My needs are to have enough power and torque to satisfy easy riding and to tow that small van without having to change down to 2nd gear on the auto all the time. 90hp will give me that power. So I will be happy with SPFI.  In the current SC set up there is ZERO lag!!  low down power is great.  when the auto changes from first to second the front wheel does lift a little if desired.



#9 Crazyeights

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Posted 26 June 2013 - 08:27 PM

I would imagine that the MPFI heads would not be worth the effort.  SPFI is still probably a better way to go, though, regardless, you may need a plenum before the MAF in order to dampen the pulses from the SC.

Brilliant! Nissan also makes a (Hitachi) SPFI unit that contains 2 injectors and flows more for the V6 used in the pickups. Take a look, this is from a 1989 D21 pickup. It is suprising to me how similar it is to the Subaru single unit.


Attached File  Nissan Hitachi TBI-1.JPG   88.22K   42 downloads

Attached File  Nissan Hitachi TBI-2.JPG   125.01K   53 downloads

Attached File  Nissan Hitachi TBI-6.JPG   107.78K   52 downloads

Attached File  Nissan Hitachi TBI-8.JPG   106.93K   38 downloads


Edited by Crazyeights, 26 June 2013 - 09:10 PM.


#10 tweety

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Posted 27 June 2013 - 01:26 AM

wow!  it is very similar. kind of like a dual throat version of the Subie SPFI.  thanks for that.  what models does the unit come in.?



#11 Crazyeights

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Posted 27 June 2013 - 03:31 AM

wow!  it is very similar. kind of like a dual throat version of the Subie SPFI.  thanks for that.  what models does the unit come in.?

1989 Nissan D21 pickup with a VG30i engine as I recall. With your blower this would be a sweet little setup.



#12 tweety

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Posted 27 June 2013 - 04:04 AM

yeh, but I get complicate-a-phobia.  Thats why I went EA81 in the first place. But my mate would likely be interested (El Freddo). I'm really going to try and be satisfied with the SPFI I'm about to install. but you never know.... thanks for the info.



#13 el_freddo

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Posted 27 June 2013 - 07:37 AM

yeh, but I get complicate-a-phobia.  Thats why I went EA81 in the first place. But my mate would likely be interested (El Freddo). I'm really going to try and be satisfied with the SPFI I'm about to install. but you never know.... thanks for the info.

 

Yeah it is interesting.  Will have to do some research on this one and see what I can dig up over here to play with!

Cheers

Bennie



#14 ivans imports

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Posted 27 June 2013 - 09:50 AM

can you pigy back a spi to run two injectors ?



#15 tweety

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Posted 27 June 2013 - 05:34 PM

El Freddo suggested the piggy back of another injector when a supercharger is switched on.  seems the most simple way to do it. I dont know enough about ECU's  though.

 

Bennie, I think the Hitachi twin unit wasnt available in Oz.  Read up on Pathfinders and D21's and the owners are suggesting imported SPFI unit the VG30i.


Edited by tweety, 27 June 2013 - 05:35 PM.





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