Polo motor build for junkyard coupe 58367

[jacques]

how about a flat fan conversion? for the real 4-Cams Polo and Type IV

[Carrera_The_Kid]

I will take one!

[JTR70]

Michael, I'll send you an email with his contact information along with a word concerning his current circumstances.

Jacques, are you now reproducing this unit including the 90 degree gearbox drive?

[Bill Sargent]

The flat fan unit shown in Jacques post is a factory one installed on a 2 liter 4 cam motor in an Elva Porsche. The owner has made a similar flat fan set up for his pushrod motor in another race car, but using belt drive, not the 90 degree gear box.

[356hunter]

Thanks Justin!

Michael Foster

[jacques]

Thanks Bill
i believe there is a desire for these it seems a better fit for cooling and clearance you have to implement a separate charging system.
j

[JTR70]

4/5/16
Getting ready to cut the cam towers down.

Dean P. sent me a pair of example towers so Bill and I could plan and get my towers cut down.

Learning a great deal and so glad to have Dean available to guide us through this. As you can see by the part numbers above Porsche did not make a designated right or left side cam tower. They are generic With the open oil inlet being the deciding factor about which side of the motor they will mount on. With this in mind Dean explained that it will always be the #3 bank that gets removed.

So on the left side the front of the tower gets cut.

Keeping the idea of the towers as being generic with it now mounted over to the right side it is the rear section that gets lopped off. Technically still the #3 bank. Hope that made sense. I really wanted to preserve the inlet opening for the mounted elbow above and so I asked him why we could not just cut the front off since they seem identical from end to end.

Dean explained that the two internal cam journals are not spaced symmetrically from end to end. Template represents the journals which are marked with green masking tape.

Once I put the template on the other side in the same orientation (preserving the rear oil feed like I wanted)the center journal is completely out of alignment and the rear journal seems off too. Dean says cutting the towers his way eliminates the need to build a right and left designated cam which makes production much simpler. Stock 911 do have a designated right and left cam BTW.


By flipping the template over on the same tower to cut it as Dean says all quickly gets right with the world.

After cutting there will be some end cap fabrication/TIG welding to be done. As you can see the New cam journal end is a few MM's short. This is due to the casting opening up down in there and this is the level it has to be turned down to catch a full flat mating surface. A spacer is required to make up this difference to bring it back to level.

Well I learned a lot about stock and shortened cam towers. Scheduling with the Bill to get them trimmed off next.
Thanks for looking!
Justin

[roy mawbey]

Justin,

That must have had him scratching his head a few times the first time he attempted this job. Its not easy to understand even with your help.

Nice photo's Justin impossible to get across without those as a guide!

Roy

[JTR70]

Thanks Roy! Part of the reason I made that template was to also get my brain around the layout of these towers so I could keep track of what is going on. ...it helped.

4/6/16
Beginning the long journey of developing paper templates for the lower housing tin.

Mocked up the left bank first. Due to high misalignment on this side I believe this will be the most difficult between the two. Famous last words.

Have to bridge that misalignment jog from the edge of the cylinders and head to the face of the housing. All the while making way for the eventual timing chain tensioner cap quickly represented by the socket and the intake manifold runner represented by the tube section.

Beginning with rough general shapes as a jumping off point to get an idea on where it needs to go.

initial closing tray idea...

Of course some internal veining will also need to be made to direct the air back over the heads but I'm a few miles away from that stage yet.

As it went I was shooting for more smooth and graceful contours

Thinking of a more swooping profile here.

Not exactly in love with it but it was the first attempt. The second template version was started this evening with better shapes and profile ideas. The best I can hope for is that the final presentation improves with each try; No short cuts there.
Second template idea next.
Thanks for looking!
Justin

[Impi]

Hi Justin is it really neccesary to have the tensioner outside the housing why not have it inside the front wall then having acurved duct on the inside. To my thinking the tensioner can be hidden behind a cover plate. From my type four upright conversion experience: try to keep the cross section of your ducting as close as possible to the area of the outlet from your fan any larger sections make the air expand and will drop the velocity you want this after your air has gone around the head and sleeves not before.
Armand

[356hunter]

Hey Justin, when and if you get the chance can you see if a distributor and cap fits without interference with 4 cam type shrouding? Thanks!

Michael Foster :>)

[JTR70]

Hey Armand, thanks for your input! No, its not necessary to have it out side of the tin, it was more toward making the simplest design that I can. A closing guide wall section will need to be there anyway so I couldn't justify double walling it to encapsulate the top of the chain box. Though smoother cosmetically the final presentation might look counter intuitive as the chain box doesn't have a need for air passing over it. The volume of air as it makes its way down to the heads will be getting squeezed tighter as its narrowing to point it back toward this bank so it should be picking up velocity? Tony has better grasp on air flow than I do so I'm just making an example that we can build on. Thanks again Armand!

Hi Michael, Unfortunately I don't have a distributor on hand but I did take these to give you an idea of the clearance:

this is a 46mm socket which was the closest representation I could find of a distributor. This configuration does not leave clearance room for distributor. The generator stand would have to be moved back a lot more.

This socket I believe is a bit smaller in diameter than a standard 356 distributor and as you can see it is well into encroaching under the generator stand. Once you add the height of a cap and wires I see no way that unit would fit. That's just considering a standard 4 pole model, if you're running twin plug heads... no way.

For some more scale the OD of the socket is about 62mm.

4/8/16
second template

Building off ideas from the first try I began the second attempt.

Basic trimming and shape profiling the corner to continue the line of off the main housing.

One of the changes that developed was tapering the rounded corner wider toward the bottom.

The main reason was to get the outer line to intersect with this corner for a better looking and cleaner transition.

Experimenting with sweeping corner profile cuts as it makes the turn inward. In the end it does have to work and do its job properly but I also need it to look as best as it can while doing it. Trying to keep any of it from looking like an afterthought.

Just as Armand suggested I was exploring all the other options and considering running the bottom the other way to cover the top of the chain box but soon abandoned the idea.

Either way a lower closing roll pan similar to this is going to be required to direct the air back towards the head/cylinder. A more complicated double wall design could also make it very tricky to both remove and install the final part.

A crucial logistical issue is clear and easy forward wrench access to these rearward generator stand bolts(eventually nuts)

Due to the way this assembly saddles down onto the block the entire cooling unit must be installed and removed as a whole. I don't have the luxury of removing the rear half and sliding it off and away to get at those rear generator stand bolts. Once the shroud halves are assembled there is no access to get at them other than at the exposed sides.



This is the right side and as you an see I only have limited access coming at it from the flywheel side. Once the long block is assembled it would be almost impossible to reach so I have to make changes to this side allowing me forward access like on the left. A total PIA but this is par for the course once you begin making drastic changes.

A lot to consider all at once but the final closing corner in the end must be easily removable so I have a shot at those rear bolts.

Began building in steel today; Up next.
Thanks for looking!
Justin

[roy mawbey]

Justin,

Your fabrication skills are really good but I am confused. I have seen in photos 4 cylinder Polo engines in the back of 356 cars. They are running examples. Have I missed something on the thread possibly way back? It seems with all this very difficult work you are doing to make sure of clearances, sheet metal fabrications etc. that this is like the first attempt.What have these other guys done? What did Dean do?

Maybe its me Justin, just tell me I am too old to follow this! A quick yes to that is no problem, as you are a very busy man indeed.

Roy

[jacques]

Hi usually the polo motors use 911 based fans and alternators. When the upright vertical 4-Cam generator/fan housing is used on a pushrod the generator is extended towards the rear to center the housing above the cylinders. The 4-Cams use a rear lid that is modified for the fan housing in this case it may be even more problematic.
j

[JTR70]

Of course not Roy, I'm always happy to answer any questions you might have. To my knowledge I'm about the first one to get this far into a 4-cam shroud conversion on a Polo motor so at this stage its sort of uncharted territory here. However, I want to give full credit where its due and say that this is by no means my original idea. The idea of mounting a 4-cam shroud onto a Polo Engine is about 8 years old and was the brainchild of the late Craig Stevenson and Michael Doyle. It was Craig who put both Michael and eventually me into contact with Dean. Back then Michael put a package deal together with Dean on several of his engine blocks for this very conversion. He had Dean leave more of the casting on top raw rather than prepping them normally for a 911 fan assembly. He took possession of the bare blocks from Dean and set about casting a few of his own parts and mounting a Kuzu version housing on at least one engine block that I know of. After bouncing from a couple of different fabrication shops...

The photo of my engine here represents about as far as his project motor got.( basic fan assembly mounted to the block) Last time I spoke with him everything was on hold.
Dean called me a few months back and was wondering how far I had gotten with my conversion as he was just finishing a motor for Seinfeld and they were interested in doing the same thing. At the time I told him I wasn't very far as I was still waiting on Bill to machine the top of the block. He asked me to keep him posted with any developments. After I got the block back from Bill I called Dean to let him know I was back on it but he said that the motor was already done and that they went with a standard 911 setup. Apparently the cost of the basic 4-cam fan unit didn't sit well with the project manager working with Dean. He could not justify investing about another half of what Deans bare motor kit costs just for the basic cooler then there would all the additional installation costs; machining and of course the tin work I'm in the middle of now. Anand Rajani is also mounting a Kuzu unit to his early 911 4 cylinder engine which was built by chuck Beck from an original cut down 911 case. His builder contacted me asked if I'd consider making a second set of these lateral closing tins for their motor. I told him I could, but I highly doubted that they would fit very well as there were way too many variables. The engine blocks are different, Their specific placement of the cooling shroud compared to mine etc etc. Didn't hear back so I assume they're doing their own thing. So there are several guys in process of this conversion but as far as I know I'm just a little further up the road with it. Again as far as I know.

4/10/16
Onto metal

had to start somewhere so I grabbed a remnant piece and began rolling in the bottom flange. I wanted smoother sweeping rolls rather than defined bends so after some experiments with various sized tubing I eventually came up with a usable profile.

Seems to be on the right track as it not only clears the chain tensioner housing outside but also continues the cooler housing floor. Sort of by accident.

So far so good. Begin rolling that corner next.
Thanks for looking!
Justin