Supercharger for Subaru?

YouTube · Post by **El_Freddo** » Tue Jul 24, 2012 11:31 pm

Tweety wrote:Hope others benefit from this thread if doing an ea81.

I'm sure it will mate! Even if it's not for a trike

Tweety wrote:With s/steel plumbing to come for the BOV link etc I'm hoping the overall package will be very attractive and interesting.

Going to SS the intake manifold to SC pipe work as well??

It'd look ssiiiicccckkkkk!

Tweety wrote:For those interested there is a Euroa show and shine first Sunday in October where Tweety will be on display with Sylvester (caravan)... By then it will well and truly be sorted...and left for many kms of reliable riding.

Please set a reminder on your phone or something to let me know the week before, we won't be very far away so there's a good chance we could be there

Cheers

Bennie

Tweety · Post by **Tweety** » Wed Jul 25, 2012 2:41 pm

No worries Bennie. Should get my bits back in the morning....play time.

Tweety · Post by **Tweety** » Fri Jul 27, 2012 9:15 pm

Its taken a while but am ready to install the new improved manifold each side of the SC12.

This is a pic of the original set up. You can see the grey airbox and how thin it had to be due to the roof frame coming very close to it as the roof was tilted back. The black manifold on the left mounts above the intake. It had an adapter/spacer alloy made by redline under it that had very littel meat to create a good seal- hence a leak.

This is the new set up. I used the spare lynx manifold half to get it shortened.. This allows for the new airbox. And I'll have one centimetre spare. The new manifold to the intake is made out of 4x2" steel tube for the top onto 75mm steel tube under to to the intake the latter being halved for the silicone tube.

Look close enough you might see the Devcon plastic steel lining insdie the lower mount to allow for smoothness for the fuel mix. Good stuff but not cheap.

Tweety · Post by **Tweety** » Sun Jul 29, 2012 7:48 pm

I've got a very annoying problem

See the engine wont idle under 3000 rpm and with the choke on. I've taken off the manifolds, checked for air leaks, redone the gasket goo. checked for airleaks on the ea81 manifold the bits I've blocked off.

I'm stumped.

Starts ok with full choke and two squirts of the throttle, runs smooth, checked jets all clear.

Post by **TOONGA** » Sun Jul 29, 2012 8:32 pm

check the gaskets on the carby for leaks, or the new shortened manifold you have had made. one or both could be leaking.

TOONGA

Tweety · Post by **Tweety** » Sun Jul 29, 2012 8:58 pm

Yes Jules, tomorrow will take the carbie off. There is a rubber gasket between the carbie and that short manifold. Have tightened those bolts. Will take off the small manifold and check for leaks. I lined the inside with plastic steel to make nice and smooth so the manifold itself wouldnt leak but there is then a gasket to an adapter plate then another gasket.

RSR 555 · Post by **RSR 555** » Sun Jul 29, 2012 9:48 pm

Does you SC turn off at idle?

steptoe · Post by **steptoe** » Sun Jul 29, 2012 10:11 pm

Don't think so as it is direct drive - no clutch.

Tweety · Post by **Tweety** » Sun Jul 29, 2012 10:13 pm

No RSR. its a draw through so a clutch pulley is not possible.

So the sC just spins with the mix. Had it idling nicely before the dyno. Then we found a leak between the ea81 intake manifold and the custom manifold I made. So we abandoned further tuning but had done most of what we wanted to do. I rode it home and we had it at high idle so it wouldnt stall.

Now I've made another custom manifold in two bits with silicone tube between. there is no leaks in that area. The new top manifold peice was taken off today and endured there are no leaks. the other side tomorrow.

Tweety · Post by **Tweety** » Sun Jul 29, 2012 10:23 pm

The symptoms are:

Need full or half choke to keep it running. Feels like it doesnt get enough fuel. Raised the floats a little and made no difference. Needs choke to start even when hot.

Think I'll bake a cake....

Silverbullet · Post by **Silverbullet** » Mon Jul 30, 2012 6:06 pm

I hate idle and starting issues, I have some idea how frustrating they can be

Tweety · Post by **Tweety** » Mon Jul 30, 2012 7:03 pm

Progress!!!! The shortened manifold and carbie were taken off. Improvements were made to the mounting of it and put back together. There wasnt any leaks here though. But there was some gasket goo that made its way to the lobes on the SC. not that it did any harm but when assembling items like the manifold I used gasket goo only on the steel meeting together. Was a bit liberal with my application.

So the problem persisted.

Off with the exit manifold. Now that it is in two peices its much easier to pull off.

I placed the face of the manifold that bolts up to the exit of the SC onto a peice of flat 10mm plate. oh boy!. There was a bow in the plate. The palte is made from 3mm steel and I suspect that it bowed upon welding it all together. This effectively meant it leaked air. The gap at one point was about 1.5mm. Gasket is .8mm.

So spent some time with the grinding wheel then a good old file. Got it pretty flat. Then assebled it. Noticed though one bolt hole was stripped on the sC. and this is the location of the leak eg where the worst of the bow is. I put it all together started it up and much better. Had an idle at last.

Now I'll take it off again and tap out the stripped hole for a larger bolt. Also I believe this was the same issue with the last custom manifold.. The error in hindsight being that 5mm steel plate would have been better than 3mm.

I think also that the jetting at the dyno tune (we went from 145 mains to 225!!) might have been due to leaks. So will organise another tune shortly. I want it sorted.

But relief tonight.

Post by **TOONGA** » Mon Jul 30, 2012 8:43 pm

good to see you got it sorted and yes 5mm steel would've been way better.

As for the jets between 145 - 160 mains should be more than enough.

TOONGA

Silverbullet · Post by **Silverbullet** » Mon Jul 30, 2012 9:21 pm

Yep 3mm can bow an amazing amount if you weld a bit hot or weld the whole lot in one long run. The key is lots of tacks and if you're really worried weld in small lengths...or use 5mm plate

Tweety · Post by **Tweety** » Tue Jul 31, 2012 8:09 am

yeh thanks SB

Taking it to my engineer today to get it refaced. that will be ok. I think the original manifold these sC's have is thin steel anyway, its all got to do with that bow. will speak to him about it and likely mill it flat.

If I replace it with 5mm now then the lower and upper peices wont line up for the silicone sleeve.

Boy I learned a lot about this project. If I had my time again I could have saved a lot of time. The next guy to do it will have an easier job if he knows the do's and the dont's.

Post by **TOONGA** » Tue Jul 31, 2012 10:18 am

Thicker gaskets ? the old cork, or rubber stuff or even silicon sheet would make for a pressure worthy seal.

Me thinks it may be time for you to invest in a alloy tig welder to make aluminium manifolds.

I would love to be able afford one then I could go nuts fabricating

TOONGA

Tweety · Post by **Tweety** » Tue Jul 31, 2012 6:41 pm

Yeh, I'm hearing you Toonga but I rang and put a stop to work on the manifold at my engineers. He was to mill the face flat.

I've purchased a 60mm silicone tube with a 45 degree bend and plan to use S/steel exhaust pipe and a new thicker face plate. I'm making it all much simpler. One of the ittues I faced with the 75mm pipe and silicone tube is that its just a little too large making some bolts'nuts hard to get at and tighten. will be working most of the night and to the engineers tomorrow. pics soon.

YouTube · Post by **El_Freddo** » Tue Jul 31, 2012 9:37 pm

Bugger mate - one more trip to the big smoke?

Hope you get it all done right this time around without any issues!

Cheers

Bennie

Tweety · Post by **Tweety** » Tue Jul 31, 2012 11:06 pm

Bennie, a trip to the city is fun for me lol. Reckon I could sell neck braces by the dozen.

Ok, my idea didnt work. my 60mm silicone tube had a 45 degree bend in it. But really the intake and the face of the SC are in line. even a 90 degree bend peice woulnt fit due to the arc of the tube.

Toonga- your suggestion of cork gaskets will be the answer- why?

Because I put a 8mm thick steel plate up against the SC face. the SC face is not flat!!!!. There is about half a mm warp. now the standard fitment of these have a thin steel/tin manifold I've seen on the web somewhere. therefore, as that is a little flexible there would eb now real need for it to be ultra flat.. my assumption.

So I'll get the last manifold milled and seek some 2mm cork gasket. will that stuff withstand petrol? suppose if it is used for sumps with oil it will. Is there a certain grade to get?

Tweety · Post by **Tweety** » Wed Aug 01, 2012 2:53 am

Mounting a Sc is the hard part. This is what I've read on many web sites.

It is easier with the trike, more room. But there is a procedure I now acknowledge as an easier method of carrying out the mounting of the unit rather than the ways in which I carried it out. It may or may not be relevant to a Subaru car but you might benefit by this example.

My first lesson was that there is no real advantage in making a (permanent) hard manifold mount between the SC and the intake. A 50mm silicone sleeve between the upper and lower mounts is a good idea as it allows for small adjustments with the SC to take place.

This is my recommendation.

Purchase a 5 ribbed belt 5pr-0965, a common size. These belts go up and down in size by 10mm which is quite a lot so you have to have some accuracy when doing this mounting procedure.

Finalise your pulley selection and fit it to the SC. I used the standard clutched ribbed pulley and removed the clutch centre and got my engineer to use 3 bolts to bolt it solid. With the crank standard pully at 150mm it works out at 6-8 psi. I've achieved 5psi as ther eis some loss with volume efficiency and I had air leaks so I might get more boost later. Not that I'm disappointed with over 30% more pwer and torque.

I would advise that if you are fitting a SC12 or 14 to your engine then its advisable to fit it as close to the intake as possible. If it is to be located between the alternator (that has the cast iron mount) and the intake hole the first thing to do is to locate the SC into its near exact position with the belt in situ tight as possible but with no adjusting tensioner fitted as yet. Take some time with a flat edge to get the belt lined up. Use whatever means to keep the SC in this position. Then fabricate a single solid mount from the intake to the SC. I would do this with 5mm steel lower mounting plate mounted directly onto the intake. make sure you tap that hole with a 12mm tap and insert a 12mm grub screw into the hole to prevent future problems with radiator fluid leaks. Seek out some 60mm or 50mm steel tube weldable thickness. You will find the Sc outlet is closer to the front of the engine than the intake hole. So your manifold will be on an angle. This is relevant to mention.
You'll need a blow off valve. When your engine backfires you need this to operate to prevent breaking stuff. I used a turbo BOV without connecting up the top vacuum hose. Worked a treat a few times when I had tuning issues. You will need to plumb this back to an air intake area. The mount that the BOV comes with is alloy. I got my engineer to turn a steel one up on a lathe. This will need to be fixed to the lower or upper manifold peices after seperation. One issue is where bolts for both ends are located. Use 75mm steel tube like I have and you have plenty of cutting and bending of the tube to ensure access to the bolt heads are gained. Smaller tube like 60mm or even 50mm allows for much more access. Nothing worse than trying to fit a nut to a stud in a crammed area. With that angle of the manifold the rear lower stud on the SC poses the most problems. Larger tube has the welds close to the bolt heads. All sorts of time wasting can be had here hence my suggestion to go smaller tube than 75mm.

So you have the SC secure with your manifold and nothing else at the moment and your pulleys are lined up within say 1-2mm. This manifold will later be cut in two peices. Now make up a lower mount under the SC. I used 10mm x 20mm steel flat. There are plenty of mounting points on the ea81. Thread through the SC mounting holes a long bolt 3/8th with nuts between the lugs and one at the end. With the "flat" bolted to the engines manifold and at the front you can weld the last nut on the bolt to the flat. Do the same with a nut up near the bolt head- that is connected to the cast mount for the alternator. I built a small steel frame here for the tensioner. The large bolt can be unscrewed when you want to take the SC off.

Make up an overhead mount. This can best be made with 20mm square steel tube running from a mounting hole near the temp sender on the ea81 manifold up to the two top mounts on the SC. I had a nice bend in the tube.

Unbolt the new manifold between the SC and the intake. Cut the tube with a 5mm slice out of the centre. At this time it is convenient to use Devcon plastic steel inside the peices to make it smooth especially in nooks and crannies where fuel can pool or minimalise friction. It is expensive but it is permanent and proven for use inside manifolds. place clamps on and the silicone sleeve. The sleeve needs to be short enough to slip down covering the lower mount. Finalise the assembly.

You will notice the SC is on an angle. It cant be mounted vertical because the alternator wont allow it. So any side draft carbie has to have a mount that allows that carbie to be flat. This is where you need a carbie manifold that allows for that angle. A cut down one, a newly fabricated one of as I ended up doning - a cut down half section of a lynx twin carb manifold. Make sure you get the vacuum holes tapped. Make up a adapater plate to the SC 5mm or more thick.

WARNING!! These superchargers have standard mounting studs for each manifold. The holes for these studs go right through to the teflon coated lobes. You must be careful if replacing these studs with bolts or if the studs screw further in than they are suppose to. The screw ends can easily hit the lobes and cause damage. It is said the teflon coating isnt that critical eg scratches and scores wont necessarily cause performance issues. But its nice to avoid it. I had a few stripped threads here. I drilled them out and tapped them. To do this make sure you have an oily rag inside the Sc to catch filings. Take care, the lobes can squash fingers and edges can cut them too as tolerances are fine and edges sharp.

You now can mount your carbie. I used a 40dhla Dell'orto. Seems an ok choice. SU's are a good choice too apparently. Design your airbox, cold air intake advised. You'll need a new throttle linkage. I sought out a EA Ford Falcon tensioner smooth pulley. This should be mounted to the "slack side" of the belt. eg opposite to the pulling side from the crank to the SC pulley - being the left side nearest the dizzy. Your belt at this time should be snug enough to jsut get it off the pulley if required. Then mount the tensioner so its pulley it all the way out. I say this because it isnt apparent that even though the belt is snug it will stretch somewhat when under tension. Tension it up quite tightly. When you first start your engine keep a close eye on the belt. If there is any minor fraying on one side or it starts to mount the ends you can ruin a belt quickly at 40 bucks a pop.

Make sure the SC has its 3 small tubes in place to allow for air pressure equalisation between the chambers, oil is replaced preferably with SC oil. I used GMH oil and you'll need two 95mm bottles at $49 each. Some say transmission oil is ok as its only gears to lubricate but I like peace of mind. Prior to putting in the oil I took off that back plate, cleaned it all inside and a little silicone on the case join. The rubber "O" ring is about 20 years old or more so a little help to keep the seal wont hurt.

Install a boost guage. I chose a digital one form ebay for $18. Nice blue digits!

TUNE. Bear in mind the issues I had with air leaks. If your manifolds leak air then your jetting when tuning will end up rich and waste a dyno. So the real benefit with the above procedure is fitting the one peice manifold between the SC and the intake with the SC in the location it will end up with the pulley's lined up. Later that manifold will be cut in two to allow for a sleeve to join them.

If I had known this before I started I would have save many days and a lot of work.