Tweety's ea81 build

YouTube · Post by **El_Freddo** » Mon Apr 14, 2014 6:24 pm

Oooh! Shiny!

I bet that will give you piece of mind Tweety

Have you spoken with the engine builder yet?

Cheers

Bennie

Tweety · Post by **Tweety** » Mon Apr 14, 2014 7:14 pm

No I havent Scott. We are driving to the Sunshine coast in June/July and will wait for after then before I will commence the rebuild.

However, these parts I'm collecting as I am about any information that can be collected to assist the builder. Cam is decided- thanks Steptoe (16/56 with .235" lift- got it right this time Jonno)

Next step might be the weber 38/38 adapter. Got a friend that does this sort of stuff. He is in Carrum Downs. He has seen the job and is fine doing it.

I'm keen to know how much porting can be done to the heads on the inlet. the SPFI manifold ends are the same as the stock EA81 which is very interesting. Subaru increased the manifold diameter by 6mm yet by not increasing the ends wouldnt it be a bottleneck? Be better if I could get a couple of mm's off the ends and the inlet to help the mix along.

Tony

YouTube · Post by **El_Freddo** » Mon Apr 14, 2014 7:21 pm

Tweety wrote:Subaru increased the manifold diameter by 6mm yet by not increasing the ends wouldnt it be a bottleneck? Be better if I could get a couple of mm's off the ends and the inlet to help the mix along.

Not a bottle neck - for traffic maybe, but for an air/fuel mixture it's all about velocity. Larger diameter into smaller = higher velocity - that's my primitive understanding. There is a point where it becomes a bottle neck and inhibit performance but that would be at higher revs IMO.

Have fun on the Gold Coast

Cheers

Bennie

Tweety · Post by **Tweety** » Tue Apr 22, 2014 10:26 pm

Saving as hard as I can to get this rebuild likely in Spring time.

I am collecting all data now for the engine builder. As most of you know I have a SPFI manifold and weber 38/38 synchronic. The 38/38 works better on a modified engine. I'm hoping that the larger manifold (by 6mm) higher compression and better cam will allow the 38/38 to work well. if not well, a 32/36 will replace it. High revs are not required. 5000rpm max is fine. Low torque is wanted.

Trike weight- 640 kgms. Camper trailer GVM 300 kgms. + passengers 220 kgms and dog, 5kgms. total 1165 total weight.

Recommend any changes by all means.

1. Rebore is a must, EA71 oversize pistons with slight head shave or O/S EA81 pistons with light head shave. (whats better to do?)seeking 9.3-9.8:1 compression

2. Camshaft 16/56 with .235" lift as tested and proven by Jonno. Nothing better than a cam that we all know is ideal .

3. Heads- it is the larger valve type. usual stuff, replace bad valves, think a slight port and polish is all thats needed. Will harder valve springs be worth the money?

4. Engine balance. A balance years ago cost a mate $200 on his lancer engine. what about now? Cost will be the factor here and if its worth it result wise. Have any of you balanced an EA81....what were the results?

5. Block- might ask him (could be a her lol) if the coolant pipe on top of the engine can be replaced as is rusty. outside blasted for new finish. Finish will be clear engine paint and black bolts/nuts. Maybe chromed valve covers.

5. Water pump is near new, new oil pump obtained, near new alternator, good stock EI dizzy, master blaster coil. new stock spark plugs (I do have iridiums but my jury is out on them until someone raves about them). Cooling- currently an Alfa frotn radiator. Soon after I get it going will buy a Porsche 911 'centre radiator that will mount at the rear of the trike and engine. its only 600x170x44mm with 4 x 6" thermo fans and a heater core off the heater in/outlets bringing the cooling capacity up to Brumby radiator size. All of this is a bit irrelevant to the build just sayin'.

6. The auto is out. its a 3 speed VW unit. It over-revs in first gear with more than half throttle indicating an oil starvation issue (guess) and has oil leaks. needs a check. will get the axle checked and seals replaced too. Torque converter is stock. Dont know if this should eb looked at also????? can any mods to it improve low down torque?

7. Exhaust. As you all noticed it a twin system with crossover pipe at the back of the sump. The exhaust (for us) is a little loud. It has a good muffler each side, the quietest the muffler shop had at the time. Also of the four exhaust pipe outlets they all have 6" motorcycle exhaust baffles making it slightly quieter. Long distance touring will be undertaken so I intend to look at this issue later. Maybe a 2 in two out small extra muffler each side will do the trick.

8. Air filter- top weber cone to cold air intake. Has a large autobarn cone filter and oiled fine sponge filter inside it. Both cleanable. Think this is really efficient.

Thats it. any ideas/views welcome.

steptoe · Post by **steptoe** » Tue Apr 22, 2014 10:45 pm

Maybe not harder valve springs. I got a set of genuuines for my EA82T - exJapan about 180 all up, inners and outers - keeps the donk as a crisp drive 87,000 later.
I think I have seen after market for EA81, no findy for the 82 though

Tweety · Post by **Tweety** » Tue Apr 22, 2014 11:26 pm

Thanks Jonno.

Exhaust- this is interesting.

http://www.youtube.com/watch?feature=pl ... uvukjbX5-M

also some idea from the 1960's open and closed

So my thoughts are, for cost reasons, maybe a washer welded to the baffles just mounted inside the tip ends would add to silencing the exhaust. I've got 4 tip ends. If I calculate the area of the Brumby exhaust area and make the four washer holes the same area in total I just might get a quieter exhaust with the correct back pressure to boot?

steptoe · Post by **steptoe** » Wed Apr 23, 2014 1:07 am

a cat really silenced my 2" EA81 no resonator just sports muffler to a level I think you'd enjoy. Cost reasons, puh! I see you wanna chrome those rocker covers - what's wrong with a bit of silver frosting from the $2 shelf ??

Tweety · Post by **Tweety** » Wed Apr 23, 2014 1:51 am

but Jonno.....the rockers have to match my 50 amp chrome alternator!!!!

but it can be done much later. and I have plenty of $2 spray cans in the shed.

am a pensioner now and joe hockey wants some of my money. lol

Tweety · Post by **Tweety** » Wed Apr 23, 2014 2:12 am

http://www.ebay.com.au/itm/Subaru-EA81- ... 1018585931

Subydoug · Post by **Subydoug** » Wed Apr 23, 2014 8:53 am

Id just get new standard valve springs Tweety. They work fine and like you said, your not chasing high rpm.

With the heads I would deffinately take them to a shop and get a 3 angle valve cut on the seats and valves. Having looked at three sets of ea heads all there stock valve cuts are rubbish.

Dont go crazy on the porting. Mainly around the valve seat where the insert is sitting in the casting. Make it a smooth transition from port to valve seat. The best porting you can do is matching all of the coolant passages between the head and block and between the manifold and heads.

That 38/38 is Huge. I hope it isnt too big.

I wouldnt weld washers into your tailpipes. Longer mufflers will drop the note. If your chasing power out of your ea81 blocking the pipe aint gonna help. Maybe look into repack-able mufflers like motorcycles use.

Regards

Doug

Tweety · Post by **Tweety** » Wed Apr 23, 2014 11:08 am

Thanks Doug. Just the sort of thing I need.

Makes sense on the valve seat 3 cut. definate there. its on the list.

I've had a 32/36 weber on tweety when I first got the engine. The orig carbie was trashed by the old mechanic that owned it. So couldnt compare performance to the Hitachi. However perhaps and likely the auto trans made it feel sluggish. I was always wanting to squeeze the throttle more to get the second throat opened up to get some reasonable acceleration from standstill. So the auto was the difference with my driveline than say all brumby utes. The 38 uses the same mounts as the 32/36 so should it be a problem easy fix. easy sell on ebay.

I've read nearly every thread on the net about the 38/38 and very few comments refer to an auto trans car. A BMW 2002 auto from an owner found the 32/36 sluggish also for that car. Makes sense that the engine has to turn that converter and push the vehicle on one small throat for economy while with the 38 a bit more fuel taking off then cruising sooner. Saying there could be a bit of compensation in that theory?

What is critical and weber say this, is that a worn engine or unmodified is not the engine for a 38. It should be in top condition and thats where the extra comp, cam, larger manifold etc come into the equation. Top end there is no difference in both carbs but low end is a huge difference. They put the 38 on MGB's and Datsun and Toyota 1600's often.

They say 2-3 mpg sacrifice. But many owners claim the boot in the arse is worth it and they swear by them. Hoping that in the end the cam and the high compression will combine with the 38 to give me more than enough low down kick off so I'm not squeezing that throttle so much. As I said the auto is the difference.

Problem with the exhaust is there is no room to put anything on it now. There is the last section of the exhaust pipe only that could take a one in two out slim muffler like a hot dog and retain the nice 4 pipe exit appearance. Again, its something that can be done later and done in situ without disassembly of things. Time to ponder on that. Or could get Rosie the foxy some ear muffs. Her and Debbie sit right above the engine and a little forward from the exhaust.

tambox · Post by **tambox** » Fri Apr 25, 2014 12:51 pm

My motorbike has got those "washers" in the exhaust, OEM, but they are controlled by a stepper motor.
They start to open at either about 4000rpm or WOT.

A return spring and a solenoid, set up through a microswitch on your throttle would be a simple way to give you what you want.
Set it to open once you put your foot down past a certain point, say 3/4 throttle. Noise and flow when you want it and quiet/restricted the rest of the time.

Tweety · Post by **Tweety** » Fri Apr 25, 2014 3:27 pm

mmm, sounds a possibility. there is a join at the bottom of each of my exhausts going from one to two pipes. could insert a butterfly washer there.

Have searched but cant find the original exhaust diameter of the ea81 brumby or leone. anyone know? Then I can calculate the hole size needed.

Plenty of thinking on this needed. I am seeking low down torque but concerned the washers could rob me of some. Then again back pressure could be a good thing.

Cruise at 105kph is 3100 rpm. If the micro switch on the throttle arm on the carbie is set to come on at 110 we'd get a nice quiet ride.

Just did some rough calculations. If ori EA81 exhaust was 1.75" diameter. Washers can have 5/8" holes (x2) to achiever same area.

Tweety · Post by **Tweety** » Sun May 04, 2014 6:51 pm

Update- zero.

Had pneumonia, gout and a hammy due to limping whith the gout lol

Be a couple of months before solid action is made. Engine is ready to go to the engine builders now.

The exhaust butterflies are also on hold. Gotta think more on that. I'm not convinced. Maybe fit a small resonator each side. Reason I'm unsure is that engine tuning is dependent on exhaust back pressure etc. So if that back pressure is altered it could cause more problems than its worth.

steptoe · Post by **steptoe** » Sun May 04, 2014 10:56 pm

how small a cat can you get to shove in as a restriction? I believe it is the key to the L Ypipe working well with my EA81, bigger pipes and the cat restriction. You have enough room to experiment with home made jobs to play with ....

Venom · Post by **Venom** » Mon May 05, 2014 5:20 am

Not sure if this is any help to you mate: "The exhaust system is next. Use 1.75 inch pipe instead of the stock 1.25 inch, which is half the cross section. This is important and accounts for about 10 HP. Run each side back to the exit and couple them together with a cross-over as close as possible to the oil pan to form an ‘H' pattern. This gives two ways out for each pulse and also reduces exhaust noise by a big amount.
Stolen from:
http://www.subarubrat.com/airscooby.htm

Reading your thread I thought airplane applications of the EA81 are probably also relevant to your trike when looking for exhaust solutions.

Tweety · Post by **Tweety** » Mon May 05, 2014 7:05 pm

Yeh Venom the exhaust was done after install. Rode trike to Shepparton with two 40cm straight outlets over there. not a roo in sight.

The system starts and runs to just past the crank pulley where the cross over to the other side is done. back to the main pipes they do a u-turn to a good muffler then another u-turn to a join then two outlets each side. its a good system, just want the best easiest way to quieten it down a bit more being an old fart. will take steptoes ideas on board.

Tweety · Post by **Tweety** » Sun May 25, 2014 9:28 pm

sorry guys, I've been ill of late and also saving for this engine rebuild is going much slower than desired. And I know zilch about Fiori's and EJ conversions. So I'm quiet ATM. Will post when there is news.

Tweety · Post by **Tweety** » Tue Jun 17, 2014 9:19 pm

Heading off interstate for a few weeks. Then the rebuild will start.

Has anyone got opinions on my specs I'm using for this recoed engine?

ea71 pistons (where do I get them?) being 40 thou taller giving 9.5:1 compression.
cam for low torque as per steptoes specs
slight port

cheers

Post by **TOONGA** » Tue Jun 17, 2014 9:32 pm

EA71 pistons from USMB

http://www.ultimatesubaru.org/forum/top ... %2Bpistons

or 1976 -1984 volvo pistons? the subaru rings fit the volvo pistons

http://www.ebay.com/itm/SUBARU-VOLVO-1- ... 36&vxp=mtr

And everything else sounds good. Would it be hard to match the inlet openings on the manifold and heads?

TOONGA