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Convert at Subaru boxer to run backwards / CCW ?
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saabmosare
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PostPosted: Sat Dec 22, 2018 3:52 pm    Post subject: Convert at Subaru boxer to run backwards / CCW ? Reply with quote

Backround
I've always had a thing for Type 1 beetles since I was a child, but it never made any sense to buy one since they are literally useless as a daily car. But I finally decided a Baja Bug with a Subaru engine would be a perfect car for me to use as an alternative for my daily one, it would also make sense since I have a reason traveling forest roads sometimes. On top of this, I enjoy building, as all of us.

So to the question. Have anyone any experience, know someone who tried or have any input for me on trying to run a Subaru engine backwards?

Why?
If I can make the engine run backwards I have an affordable engine, a gearbox strong enough and a low gear. All of this would fit me perfect. I mean, perfect. No, I don't want to flip another gearbox around. I want to pick as much as possible from a donor car to get more modern functionality but my bug look.

What I know so far:
Pistons are not affected on a change from CW to CCW.
Camshafts seams to be designed in a way so it does not matter what way they rotate. They lift and close at the same pace regardless of rotation and the angle between the vales is the important thing.
Ignition should be solved by rearranging the order of the cylinders, the timing in between the spark will be the same.
Water pump, oil pump and the generator are on the same belt with tensioning wheels. Based on what I have seen so far it should not be any major problem to rearrange the order to make them spin the right direction in CCW.

Actually, I believe the only thing needed would be to adjust the timing of the camshaft and belt to open and close for rotation CCW rather than CW. Can it really be that simple? Opinions?

Since adjusting the belt would also allow the motor to use the exhaust side as the exhaust side still. Because the valves would behave just as before. Just in another timing.

Would I possibly have any lubricating problems from the motor spinning the other direction? I'm thinking if the rotation is used to throw oil at some special places etc.

I'm quite familiar with motors and gearboxes and got an engineering background. But I have never ever before felt such a need for running an engine backwards.

Solution:
I came to a conclusion recently on how to solve my problem. I'll list them all here, and in the initial post for others to follow if you have the same issues.

I'll pick one of the following combinations for my purpose. They both offer a great and reliable engine and a very affordable price/performance ratio. Engine and gearbox are already mounted so no adapters needed. The only issue is the RBGs, but I don't think it will be any major issues while I anyway will rebuild the IRS. So better do all changes at one place instead of everywhere.

Will use one of those setups:
VW 1,9 TDI PD engine with longitudinal mounted gearbox + 1,26 RBGs
Subaru EJ20 engine with 5MT Gearbox + 1,26 RBGs
Both setups can be manual or automatic, haven't decided what to choose for myself yet. Depend on what shows up for sale I guess.

Pros and cons VW
A lot of torque and low HP. Perfect for insurance and tax purposes since they don't care about the torque while I do. Low fuel consumption and considered a great engine for longevity. Higher centre of mass than the Subaru engine so will be more unstable in corners.

Pros and cons Subaru
Boxer engine with a low mass centre. Will handle great in an old car and give it great handling. High revs and great sound. Decent torque for a petrol engine. Considered a great engine that lasts very long. Can use the Subagears if I somehow don't manage to source the RBGs. Pricy, but a solution.

Other ways to solve it
Some other ways to solve the issues I found but decided to not follow.
Reverse rotation on the engine. VAG 1,8T seams to be okay, I haven't found anything that says it won't be possible on the Subaru EJ20 engine either. My concern is spinning the gearbox the wrong direction in the long run. If the engine was not a tail engine it's important to keep the crank rotation in the opposite direction compared to the wheels to make the car stay stable.

Flipping a gearbox upsidedown. Seams not too complicated but will change the mounting of the engine to a lower stance, not something I'm too keen on. The gearboxes seem to handle it well, keep in mind that new vent and so on is needed, and you probably need to find a new oil level based on your setup.

RBGs for obvious reasons, thanks for the suggestion guys! This helped me a lot. Both the 1,26 and 1,40 would be okay for my application.

Subagear pinion and crown wheel. Pricy but solves your issue quickly.


Last edited by saabmosare on Thu Jan 24, 2019 2:02 am; edited 2 times in total
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gprudenciop
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PostPosted: Sat Dec 22, 2018 4:00 pm    Post subject: Re: Convert at Subaru boxer to run backwards / CCW ? Reply with quote

You would need to run an external oil pump.I looked at this when I did my swap!! You would route the timING belt over the crankshaft and reposition the idlers and belt guide. Run a 36-1 crank gear.megasquirt....
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Bruce Amacker
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PostPosted: Sat Dec 22, 2018 4:05 pm    Post subject: Re: Convert at Subaru boxer to run backwards / CCW ? Reply with quote

Pistons probably need to be flipped over- usually the pins are offset slightly to one side. If there is a windage tray or anything that controls oil spray, that will need to be flipped/modified also. I built a reverse Corvair many years ago for my rail.
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modok
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PostPosted: Sat Dec 22, 2018 4:19 pm    Post subject: Re: Convert at Subaru boxer to run backwards / CCW ? Reply with quote

Can you run it backward? SURE,
is it hard, yes, but I think we sure can do it.


What I DO NOT know is if the transmission will work as well rotating backward. thrust forces on the gearsets will be reverse and that may need to be looked at.

Subaru engines are higher level difficulty than old Vw, if you are "going in" and modifying parts I don't see any rational reason that it would be easier than building an equivalent air cooled engine.
The oil pump is directly on the crank and will need to make a new gear housing to pump backward. The timing belt needs to be re arranged so the hydraulic tensioner is on the other side,
I am not sure if the pistons have offset pins, but either way it's no a problem.
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Krochus
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PostPosted: Sat Dec 22, 2018 4:28 pm    Post subject: Re: Convert at Subaru boxer to run backwards / CCW ? Reply with quote

You could just buy a subarugears reversed final drive gearset

Just sayin
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PostPosted: Sat Dec 22, 2018 4:36 pm    Post subject: Re: Convert at Subaru boxer to run backwards / CCW ? Reply with quote

The cams are not symmetrical on some models. One exhaust valve opens ahead of the other.
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PostPosted: Sat Dec 22, 2018 4:37 pm    Post subject: Re: Convert at Subaru boxer to run backwards / CCW ? Reply with quote

Just Curious why you think they are useless as a daily car ? Since they are the longest produced car with the same basic shape and running gear ever and that record will most likely never be broken .

I'm driving an air-cooled Ghia as a daily 160 whp , and have had a Split camper with 115whp ,A/C, 4 wheel discs etc since 1998 also a daily .
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modok
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PostPosted: Sat Dec 22, 2018 4:50 pm    Post subject: Re: Convert at Subaru boxer to run backwards / CCW ? Reply with quote

Hmmm, yeah those of us daily driving might take offense Wink
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PostPosted: Sat Dec 22, 2018 5:51 pm    Post subject: Re: Convert at Subaru boxer to run backwards / CCW ? Reply with quote

I have a 2006 Subaru LegacyGT...supposed to be my daily driver. Every so often I have a mysterious, incredibly frustrating, dead car. NOT battery related. Guess what I drive to work when the Subaru won't start...my '73 Super Beetle. Pretty sad when a 45 year old car is more reliable than a "modern" car.

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gprudenciop
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PostPosted: Sat Dec 22, 2018 7:36 pm    Post subject: Re: Convert at Subaru boxer to run backwards / CCW ? Reply with quote

As a person who dailys a bug it depends.if you are in cali with the same weather it's not bad but if you are in an area where the weather changes/ altitude, than my subaru motor is alot more reliable.no changing jets depending on season not one single spare part in the car!normal travel times when on a trip.so if it takes you 18 hours to southern cali in a honda that's what it takes me in my 1960 bug!!!also it cost me less to build my subaru engine than my 2276......all new parts...I also understand its not for everyone but it is an option....there are also different levels of daily!!! In the winter I would take out the passenger seat so I could run my heater buddy bolted to a board when it snowed....
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PostPosted: Sat Dec 22, 2018 8:50 pm    Post subject: Re: Convert at Subaru boxer to run backwards / CCW ? Reply with quote

I daily drive my 67. Rain, snow, sunlight.....
In the winter time. I place a ceramic heater in the passenger footwell to keep the interior warm for dry on my short drive to work. And yes I unplug the heater before leaving the driveway.
I hate wiping the windshield with a cloth. EVERY 5 seconds.

What are you referring to as a "heater buddy?"

gprudenciop wrote:
As a person who dailys a bug it depends.if you are in cali with the same weather it's not bad but if you are in an area where the weather changes/ altitude, In the winter I would take out the passenger seat so I could run my heater buddy bolted to a board when it snowed....

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saabmosare
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PostPosted: Sun Dec 23, 2018 1:03 am    Post subject: Re: Convert at Subaru boxer to run backwards / CCW ? Reply with quote

gprudenciop wrote:
You would need to run an external oil pump.I looked at this when I did my swap!! You would route the timING belt over the crankshaft and reposition the idlers and belt guide. Run a 36-1 crank gear.megasquirt....


I see. The oil pump is the only feature positioned at the crank as far as I understand. All other features is on the belt.

I was giving to skip megasquirt be rearranging the wires. But sure it would be a something to add in the future.
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saabmosare
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PostPosted: Sun Dec 23, 2018 1:08 am    Post subject: Re: Convert at Subaru boxer to run backwards / CCW ? Reply with quote

Bruce Amacker wrote:
Pistons probably need to be flipped over- usually the pins are offset slightly to one side. If there is a windage tray or anything that controls oil spray, that will need to be flipped/modified also. I built a reverse Corvair many years ago for my rail.


I get your point but as far as I can see I don’t see the need for this. Some connecting rods seams to have a non symmetrical design. So I guess those should be avoided. But piston wise, I neither can see that they should differ, nor see any reason why I would need to flip them 180 degrees. Can you explain a bit more so I can fiollow your thoughts?
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modok
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PostPosted: Sun Dec 23, 2018 1:17 am    Post subject: Re: Convert at Subaru boxer to run backwards / CCW ? Reply with quote

Jeez, I said it was no problem.
You figure out the timing belt I will handle the pistons, and then just need to get somebody to do the oil pump. Teamwork is good.
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saabmosare
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PostPosted: Sun Dec 23, 2018 1:21 am    Post subject: Re: Convert at Subaru boxer to run backwards / CCW ? Reply with quote

modok wrote:
Can you run it backward? SURE,
is it hard, yes, but I think we sure can do it.


What I DO NOT know is if the transmission will work as well rotating backward. thrust forces on the gearsets will be reverse and that may need to be looked at.

Subaru engines are higher level difficulty than old Vw, if you are "going in" and modifying parts I don't see any rational reason that it would be easier than building an equivalent air cooled engine.
The oil pump is directly on the crank and will need to make a new gear housing to pump backward. The timing belt needs to be re arranged so the hydraulic tensioner is on the other side,
I am not sure if the pistons have offset pins, but either way it's no a problem.


Is it anything else you identify right now that would care any major issues? For me, it feels strange if all it takes is to adjust the timing belt and sort out the components that now would run backwards, pumps etc. The biggest issue there seems to be the oil pump to far. But I've also started to question if I can actually use the stock camshafts or not. From the beginning, I came to the conclusion that they would be possible to run (if symmetrical). But now I have started to question if my thoughts are correct.

Regarding the gearbox, I did foresee this. I assumed that it would be okay since the subarugears worked. But now I realize they only flip the direction on the output axel. The rest rotates the normal way. One thing I see right away is the angled gears would cause an issue if run in reverse. I guessed the gearbox would not shift so smooth anymore. But I need to analyse that a bit more.
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saabmosare
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PostPosted: Sun Dec 23, 2018 1:23 am    Post subject: Re: Convert at Subaru boxer to run backwards / CCW ? Reply with quote

modok wrote:
The cams are not symmetrical on some models. One exhaust valve opens ahead of the other.


Thanks for the input. I guess those engines is not an option then. Smile
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modok
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PostPosted: Sun Dec 23, 2018 1:31 am    Post subject: Re: Convert at Subaru boxer to run backwards / CCW ? Reply with quote

maybe, or maybe not, many things are possible with enough time and $$$

Last edited by modok on Sun Dec 23, 2018 1:34 am; edited 1 time in total
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saabmosare
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PostPosted: Sun Dec 23, 2018 1:33 am    Post subject: Re: Convert at Subaru boxer to run backwards / CCW ? Reply with quote

Krochus wrote:
You could just buy a subarugears reversed final drive gearset

Just sayin



I know. But for the same price as those parts, I can buy both a beetle, a Subaru and all of the materials more or less. Except for the shocks and dampers probably.

I'm not aiming for anything to showcase. Just a fun car that would tick some boxes for me. A lot of bang for the bucks is one. And I know the cost will run away anyway once you get started unless you wanna end up with a half finished project sitting in a garage. So I rather save the money for later to finish the project when the excitement is lower.



Regarding the daily driver
Perhaps some of you see it as an option. I live in Scandinavia. Distances are longer, climate differs and a Subaru engine and gearbox would improve the odds for me actually using the car. And that's important for me to not only use the car on Sundays. Life is too short to not enjoy regularly.
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modok
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PostPosted: Sun Dec 23, 2018 1:37 am    Post subject: Re: Convert at Subaru boxer to run backwards / CCW ? Reply with quote

The main problems I'm having is the car is too light, not aerodynamic enough, rusts out every ten years,and will probably kill me in a crash. The engine is ok. Laughing
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saabmosare
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PostPosted: Sun Dec 23, 2018 1:42 am    Post subject: Re: Convert at Subaru boxer to run backwards / CCW ? Reply with quote

modok wrote:
maybe, or maybe not, many things are possible with enough time and $$$


Time should be fine, its a hobby and I don't need to bill the hours. Very Happy
But moneywise, I don't see why it would be expensive. If the cams need to be redone, yes. Then it starts to cost. But then the subarugears would be the alternative cost and probably a better alternative taking into account we already know it will work.

The major issues could rather be spinning the gearbox CCW as modok highlighted. According to me, that could be a major issue making it not worth running the engine backwards. But regarding the engine, I'm still optimistic.
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