John's EZ36R H6 818R Build

[Hobby Racer]

New valves lapped in and the head reassembled. Tomorrow I'll fit the cams and front timing chains. By the weekend it will be running again!

[Frank818]

I admire how super quick you are at removing and reinstalling your entire engine/drivetrain.
Crossing fingers on 22nd...

[Sgt.Gator]

I was thinking about your vibration issue. Flywheel bolts coming loose can sometimes be traced to a bad harmonic balancer. On Subaru engines the oem balancer is a known failure point. And it's not a harmonic damper, but rather a harmonic balancer.

I did a search for Porsche Damper and found this:
"I have just been reading Paul Frere's book - 911 Story (In 1973) The Carrera RS 2.7 became the base for a racing version which immediately outclassed everything that had been developed before. Running as a Group 4 GT car, full throttle let more than 300 bhp loose. A remedy for the crankshaft breakages was found in the use of a damper at the rear end, but there were still some difficulties with the flywheel occasionally coming loose."

And:
"The Porsche GT3 engine seems to be having its fair share of vibrational failures. We have seen crank pulley bolts and flywheels come loose, cam actuators come apart and in our own particular case we had an engine that broke the scavenge gears inside the oil pump. I know of other GT3 engines that have had similar failures. These failures are not new to the Porsche Boxer engine."
https://www.dundonmotorsports.com/pr...armonic-damper

Have you replaced the oem crank pulley with a new one? Unfortunately Fluidamper & ATI don't make harmonic dampers for the Subaru H6.

[Hobby Racer]

I am using the OEM crank pulley with thick rubber damper.

I have not had any issues with the flywheel or clutch bolts coming loose. I did however have the ring gear bolts come loose in the transmission. After that I safety wired everything just in case.

[Hobby Racer]

I had my 6 speed transmission apart again ... This time I was replacing the reverse idler gear and synchronizer that I trashed at VIR this summer. While reassembling the case, the very last bolt I put back in snapped the case boss that it threads into!





I was crushed. I thought I would have to find a new case or worse an entire transmission to fix this. The service manually says this 14mm bolt needs 35ft-lbs of torque. I thought to myself, that seems really high for this bolt, and as I was tightening it a sudden crack and the thread boss snapped right off.

I started looking at what this ball detent & springs function was. From what I can determine it has no relevant use at all! The shaft it pushes against has no detent groove, so what's it doing?

Armed with that knowledge I decided to NOT reinstall the detent ball and spring. To keep the oil from leaking out I drilled & tapped the hole for a 3/8 NPT hex plug and sealed up the hole. I know mixing metric and standard hardware is not a good thing, but I did not have any metric plugs or plug taps. Use what you got.



Best part was that I did not have to completely disassemble the trans to make the fix.

If anyone has an idea what this detent was for, let me know.

Here is a pic from the service manual to show the relative location of the detent.

[Frank818]

Oh god! Should that be considered pure luck or bad luck....

Use what you got and drive with quick fixes.

I think you did a pretty darn good job at plugging it. When should we expect an answer on whether that thing was useless or useful?

[Hobby Racer]

Oh god! Should that be considered pure luck or bad luck....

Use what you got and drive with quick fixes.

I think you did a pretty darn good job at plugging it. When should we expect an answer on whether that thing was useless or useful?

Well it shifts through all the gears correctly. I should have the driveline back in the car and taken for a test drive next week.

[Santiago]

If anyone has an idea what this detent was for, let me know.

Wait, wait! I can be useful! (...how odd...)

I know that dude: https://thefactoryfiveforum.com/show...l=1#post455839

This is (one of) your shift fork detent ball/springs. The shaft should have detents on it, but you may not be able to see it if you just put a flash light through the hole. You would have to move the rod through its full range of motion and look carefully to notice the detent (even then it can be hard to see).

Your trans will shift through the gear without it because that's a function of the gear engagement, so no wonder there that everything moves correctly sitting in the garage. In my case I repaired it because I didn't know if the detent ball (a) provided just enough resistance to hold it in gear under use, (b) to prevent overthrows, or (c) if it was just an additional tension to make it easier to get into gear. Can't speak to it's design intent.

If you follow the post I put up, you'll note that the little detent has one noteworthy advantage: it prevents the shift rod from sliding out of its internal boss when you open the case up. That would have saved me a lot of angst, but mine was an admittedly odd circumstance.

Oh, almost forgot: I also came across unusually high torque numbers for this guy. I seem to recall also coming across much lower figures (like 13-14 ft lbs), so I went with the later the second time around.

[Hobby Racer]

Wait, wait! I can be useful! (...how odd...)

I know that dude: https://thefactoryfiveforum.com/show...l=1#post455839

This is (one of) your shift fork detent ball/springs. The shaft should have detents on it, but you may not be able to see it if you just put a flash light through the hole. You would have to move the rod through its full range of motion and look carefully to notice the detent (even then it can be hard to see).

Your trans will shift through the gear without it because that's a function of the gear engagement, so no wonder there that everything moves correctly sitting in the garage. In my case I repaired it because I didn't know if the detent ball (a) provided just enough resistance to hold it in gear under use, (b) to prevent overthrows, or (c) if it was just an additional tension to make it easier to get into gear. Can't speak to it's design intent.

If you follow the post I put up, you'll note that the little detent has one noteworthy advantage: it prevents the shift rod from sliding out of its internal boss when you open the case up. That would have saved me a lot of angst, but mine was an admittedly odd circumstance.

Oh, almost forgot: I also came across unusually high torque numbers for this guy. I seem to recall also coming across much lower figures (like 13-14 ft lbs), so I went with the later the second time around.

I did remove the back cover to pull the shaft out and look for detent notches. There were none (even when looking under a magnifying glass!. My guess it that, as you mentioned, it is there to hold the shaft in place during assembly at the factory as the shaft will easily slip out until the back cover is placed on if the detent does not push against the shaft.

[J R Jones]

John, I expect that it has occurred to you to integrate the detent parts with an NPT fitting, now that you have altered the FM threads. No offence, that seems better than Santiago's fix. A brass fitting with (external) hex would give you something to work with.
BTW detents are low load devices, high torque should not be required. The gears stay engaged by draft on the shift dogs.
jim

[Hobby Racer]

John, I expect that it has occurred to you to integrate the detent parts with an NPT fitting

Yes I did consider that, but since the shaft had no detent notches it serves no purpose for me. I'm not mass assembling this so its just unneeded parts.

I was quite mad that the FSM had such an egresses error though. I need to listen more to my inner voice on these things.

[Hobby Racer]

Now for some good transmission news. I redesigned my transmission cooler setup. If you recall the last setup had the cooler mounted to the wing support near the top of the rear engine cover. While functional it required longish hoses and every time I needed to remove the engine or transmission the lines would have to be removed and it always made a mess.

I wanted something mounted to the transmission itself that is self contained and stays connected to the transmission when removing it from the car (which unfortunately is often ).



In place of the thick bulky hoses I used 3/8" aluminum hard lines. This makes it much more compact and I was able to hug the transmission case. I mounted the cooler bypass to the right side of the transmission with a custom aluminum bracket that bolts to the case using two factory tapped holes that weren't being used. I also fabricated up some sheet metal brackets to hold the cooler on top of the transmission. A new fiberglass duct was made to route the cooling air from the side vent to the cooler.

IMG_20211103_114127304.jpg IMG_20211103_114133554.jpg IMG_20211103_114138864.jpg IMG_20211103_114151914.jpg IMG_20211103_114108514.jpg

[biknman]

That's freaking awesome! You know you could easily sale a few of those setups to pay for yours if you wanted to. I'd be the first to buy one! Again awesome work!

[Frank818]

Man I didn't know it was possible to turbo a transmission...

[maclonchas]

Hobby Racer,

I know this is an old thread, but just a simple question for you on your notch outs. What did you use to cut the frame, a sawzall or other special tool?

Thanks

Bill

[Hobby Racer]

Hobby Racer,

I know this is an old thread, but just a simple question for you on your notch outs. What did you use to cut the frame, a sawzall or other special tool?

Thanks

Bill

All the cut outs were done with a 4 1/2" angle grinder using a cut off wheel and finished off with a grinding disc. Super simple tools but very effective!. The rounded scallop of the top cut out is the same shape / diameter as the grinding wheel, that's how I got it so nicely shaped.

[maclonchas]

Hobby Racer,

Know this is an old thread, but you have been helpful so far. Two questions for you. The link you gave for the Griffin double pass radiator, is it the exact one you bought. I like the install you did and contemplating using it. I did not notice any fans for the radiator. Any insight would be greatly appreciated.

Thanks

Bill

[Hobby Racer]

That is the one. Double check all the dimensions first before ordering one to ensure they have not changed it since I ordered mine. Also, my bottom outlet tube is slightly angled inward about 15 degrees, I would get a straight bottom outlet if I were to do it again so double check with Griffin about the inlet and outlet tube angles first.

[maclonchas]

Hobby Racer,

Thanks and will check dimensions before ordering. I will send out a note on separate thread for someone in the build stage to give me current dimensions. Did you use radiators fans or go a different approach.

Thanks again

Bill

[Hobby Racer]

Hobby Racer,
Did you use radiators fans or go a different approach.

Oops, I forgot about that part of your question. I do not use radiator fans as it is a race car. There is no sitting in traffic or driving around slowly. Its either going 100+ mph or its in the pits waiting to go out again

[maclonchas]

That is what I thought. Just needed to confirm. On my list to define yet.

[Hobby Racer]

This is a long one, you've been warned.

I've been having issues since last fall with the timing chain jumping on the driver's side (left hand side of the motor). It started last August, some of you may remember as I posted about it the first time it happened.

This is NOT how you want your track day to end!

It has jumped 3 times now! The EZ36, being an interference motor, bends all the valves on the left side each time the chain jumps the cam sprockets. Fixing it involves removing the motor and tearing it down nearly completely to get the left side head off to replace the valves and fix any ancillary damage. Luckily, when I built the bottom end I used quality forged components, including the pistons, so nothing down there has suffered any significant damage each time. But it is still time consuming and $$$ to fix, not to mention depressing. I think I have a solution now, and if I don't, I'm moving to another motor type.

I'll walk you through each failure and what I did to fix it.

First Failure:

Last fall the chain jumped for the first time and as stated in my old post, I believe it was caused by the tensioning arm not maintaining pressure on the slack side of the chain during rapid engine deceleration. During the post mortem I noticed the oil pressure relief valve had worked its way out of the tensioning valve causing it to exert very little force on the tensioning arm. I fixed that issue and reassembled everything.

Second Failure:

This happened right after the first failure in late fall. I never posted anything about this one, but here it goes. When I pulled the timing chain cover I saw the chain had once again jumped but this time it did not come off the cam gear sprockets. This resulted in NOT bending all the valves as the motor never lost proper timing. While researching what could have caused it this time I noticed the mounting boss cast into the block for the long tensioning arm was slightly damaged, causing the arm to not be aligned perfectly at the farthest point by the intake cam gear. This damage most likely happened during the first failure but I did not notice it. The red arrow on the left points to the pivot point in question, the middle arrow shows the tensioning arm pushed behind the timing chain and the arrow on the right shows that the chain never left the cam sprockets during this failure.

2nd_failure_1.jpg 2nd_failure_2.jpg

To fix the pivot boss I carefully sanded the boss to bring its surface back into the right plane so that a new tensioning arm would have perfect alignment with the intake gear at the farthest point. I figured this would solve the issue and it was after all my fault for not inspecting the block more carefully during the first failure. Sorry, but I didn't take any pictures of the boss during this repair but you'll see it in the next repair.

Third Failure:

Fast forward to this summer. I got a late start racing this year so my first outing wasn't until July. During the second session of the first day the chain jumped once again. This is really getting old now. After the tear down I see that the chain jumped the sprockets, wiping out all the valves again. This time the pivot boss was seriously damaged, requiring me to mount it up on my milling machine to machine off 0.150" of material then drill out the damaged threads and insert a helicoil.

First pic shows the damage to the pivot boss. Notice the cracking and the oval shape. It should be round! The second shows my bent valves. The third is me mounting the block onto my mill (this was sketchy and a very tight fit with tooling). The last two are me milling down the boss to get rid of the cracks. I covered everything to prevent chips from getting into the motor during the machining.

3rd_failure_2.jpg 3rd_failure_3.jpg 3rd_failure_4.jpg 3rd_failure_5.jpg 3rd_failure_6.jpg

Here is the finished boss after milling, drilling, tapping, and inserting a helicoil. With a small spacer it should be good as new.



Analysis:

So why did this happen a third time? Here is my breakdown. Each failure happened when I jumped out of the throttle after being under a hard load. This caused a drop in oil pressure while causing slack to develop in the chain. Those two issues combined with the very long tensioning arm that is unsupported at its farthest point are a recipe for disaster in my opinion. This is a design flaw in the EZ36 when its used in a performance application. To fix this issue (I hope for the last time) I am designing a support that will constrain the tensioning arm close to the point where the chain leaves the tensioning arm and engages the intake cam sprocket. Think of it like the chain the derailleur on your 10 speed bike. It keeps the chain running on the sprocket.

I am still waiting on a head gasket and a new tensioning arm from Subaru, but I will post pics of the solution I fabricate when its done. Here is a pic of the motor waiting for the parts so I can reassemble it.



As I stated earlier. This will be the last time I fix this motor. If it fails again, I'm moving on to a different power plant. I already have three choices in mind.

[Rob T]

Hobby: Sorry to hear of your troubles. Putting the block on the mill was very impressive. Best of luck with the modifications. Hope we can meet on a track some time soon....

[cob427sc]

Reminds me of years ago when I was running a Porsche 914-6. Early 911 series engines also used a full hydraulic chain tensioner for the timing chain and occaisionally they would fail with disasterous results (actually split a engine case once!). Solution back then was to put a steel adjustable ring around the tensioner so that the piston couldn't retract and allow the chain slack to allow the timing chain to jump. For some reason, this failure also seemed to occur after deceleration from a hard run. Porsche later developed a better system and most everyone upgraded to the newer parts. It was both frustrating and expensive when this fault showed up. Best of luck developing a fix.

[Hobby Racer]

Hobby: Sorry to hear of your troubles. Putting the block on the mill was very impressive. Best of luck with the modifications. Hope we can meet on a track some time soon....

I would like that. I definitely want to go back to VIR. It was a beautiful track and I didn't get to drive it much

[J R Jones]

John, Have you considered an Accusump accumulator to supplement oil pressure during momentary off-throttle?
Location might be important.
jim

[Hobby Racer]

John, Have you considered an Accusump accumulator to supplement oil pressure during momentary off-throttle?
Location might be important.
jim

I've used them in the past and am not a fan. They really only provide oil flow and not pressure. I really think its mostly the poor tensioner design myself.

[J R Jones]

Given the canister volume an Accusump cannot supply (diminishing) pressure for long.

Without personal experience I have read that some simpler timing chain systems have been reworked to static tension and manual adjustment as required. Not unlike a motorcycle drive chain.
That would be risky as the first H6.
Eliminating the hydraulics and reworking to spring load only would also be experimental.

Free reving with the cover off would be an interesting and messy way to observe the dynamics.
jim

[Sgt.Gator]

Dang! I feel your pain!
Does the EZ30R suffer from the same design flaw?

[Hobby Racer]

Dang! I feel your pain!
Does the EZ30R suffer from the same design flaw?

I don't know. I've never seen the chain configuration on an EZ30R. It should be very similar, except that the EZ30R does not have AVCS on the exhaust cam.

Well, if I do get it to run reliably I'll have beaten a path for the next guy

[Sgt.Gator]

I don't know. I've never seen the chain configuration on an EZ30R. It should be very similar, except that the EZ30R does not have AVCS on the exhaust cam.
Well, if I do get it to run reliably I'll have beaten a path for the next guy

I looked it up in the H6 Technician Manual 104-H6. The design is very different, the EZ30R uses two timing chains compared to your EZ36 that uses 3. It has the oil pressure activated chain tensioners but they are different. It may suffer from the same issue though when decelerating.

If you make a switch to a new engine which three are you considering?

[Hobby Racer]

If you make a switch to a new engine which three are you considering?

In order of preference:

1) Honda K20C1 2.0L (used in the new Civic Type-R 306hp turbo)
2) Ford Ecoboost 2.3L (used in the new Mustang 310hp turbo)
3) GM 4.3L EcoTec3 LV3 V6 (used in Silverado/Sierra 285 hp N/A)

Each has their pros/cons and all would require frame mods unfortunately.

[J R Jones]

John, I have done development for several OEMs and be assured Subaru has experience with the problems you have encountered. No one punishes products in development like an OEM
The problem is networking to get inside information. Back in the seventies we were successful in SCCA Nationals and went for a sponsorship to run a Toyota in the Daytona 24hr. We threaded through a dealership to the CA Toyota headquarters and established ties with engineering. They shared performance data and inside information. In the end upper management nixed the deal still smarting from the bad experience with Carroll Shelby and the 2000GT.
We had the Celica already in development, but not enough money to finish a 24 hr. car. We put the Celica back together and prepped it for SCCA Showroom Stock Nationals to get experience. The car was bullet proof but slow. We applied basic racing technology and started taking podiums. The Toyota engineering guys were delighted and followed us, sending tips and "special parts" that tested well for them. Despite starting the season in July, we got an invitation to the Runoffs. The car was blatantly illegal and we took a pass on the season finally, We did not want ourselves or Toyota to look unfavorable. Subaru has the experience, getting inside confidentially is the challenge.
jim

[Hobby Racer]

I always try to find the simplest solution to a problem. Making something overly complex is never the smart way to fix something. With that in mind here is my solution to constraining the chain tensioner for the LH side timing chain on my EZ36.

Left to right we have a custom machined 0.160" aluminum washer to replace the material I machined away from the mounting boss on the block. Next is the an oil galley plug welded to some 0.750" diameter steel rods that have been machined and offset. Lastly is a stock fender washer and 1/4" flange head bolt. Simple, right?





Here is how it all comes together. I use the large diameter oil galley plug just above the free end of the tensioning arm as an anchor point since its beefy and in approximately the right place. I carefully machined and welded the 3/4" rod pieces to the plug, forming a constraint for the tensioning arm. The only direction the arm can move now is downward to put tension on the chain. I machined in about 1mm of clearance between my solution and the tensioning arm on the three constrained sides.

I'm hopeful this will do the trick. If I can get it all back together by the weekend I'll be able to get back to Watkins Glen on Monday and Tuesday of next week to test it out. Wish me luck!

IMG_20220802_191836884.jpg IMG_20220802_183341034.jpg IMG_20220802_192159359.jpg IMG_20220802_192001174.jpg IMG_20220802_192227218.jpg IMG_20220802_191617543.jpg

[J R Jones]

I think I understand this tension scheme and I have concerns.
Did you weld your eccentric journal at the exact point of expected chain tension, with the plug properly torqued?
If that is the case then there is no adjustment available, more or less tension.

If this eliminates chain jumping are you considering an oil galley plug-stud with an eccentric lobe that can turn to optimum tension and be secured with a nut?
The force on this tensioner may be formidable, more plug thread/engagement would be reassuring.

An unknown is if the engine grows at operating temperature. That could put more tension on the chain.
If that is the case, a soft eccentric lobe might adsorb the added tension. Urethane?
jim

[Hobby Racer]

I think I understand this tension scheme and I have concerns.
Did you weld your eccentric journal at the exact point of expected chain tension, with the plug properly torqued?
If that is the case then there is no adjustment available, more or less tension.

If this eliminates chain jumping are you considering an oil galley plug-stud with an eccentric lobe that can turn to optimum tension and be secured with a nut?
The force on this tensioner may be formidable, more plug thread/engagement would be reassuring.

An unknown is if the engine grows at operating temperature. That could put more tension on the chain.
If that is the case, a soft eccentric lobe might adsorb the added tension. Urethane?
jim

The plug was welded with the plug torqued AND about 0.040" extra clearance between the arm and the constraint. There is no adjustment available but there is clearance. Note that the stock hydraulic tensioner valve IS being retained even though it is not pictured in my post. This should take care of any growth/slack issues. The constraint is only there for when the factory solution poops out and does not do its job correctly

Remember this is on the slack side of the system and does not see much tension. The factory system is only pushing on the arm with oil pressure acting on a 3/8" diameter piston so maybe 10lbs of force.

[J R Jones]

John, Ahh, you might say your device is shoe retraction limiter. That is appropriate.
How much travel does the tensioner piston have, slack to tight?
Yes I calculate 7.7 lbs. pressure @ 70PSI. That does not seem like a lot.
0.040" is a good call.
jim

[J R Jones]

John, I imagine that the chain guide shoe could displace sideways from the chain path, and your travel limiter has the potential to control that.
If side-stepping is not the issue, could a limiting sleeve-stop over the tensioner piston accomplish your experiment?
jim

[Hobby Racer]

John, I imagine that the chain guide shoe could displace sideways from the chain path, and your travel limiter has the potential to control that.
If side-stepping is not the issue, could a limiting sleeve-stop over the tensioner piston accomplish your experiment?
jim

Looking at the aftermath of each failure, the guide was always pushed to one side or the other of the correct chain path. It is hard to determine if the guide slid over and that caused the chain to jump or the chain jumped due to lack of tension and then pushed the guide to the side.

I figured it best to be safe and implement a solution that covers both issues.

[Frank818]

Terrible, John, terrible. I fully understand those issues "that come back and are a PITA to sort-of-fix each time".
In a way I kinda hope you swap engine, although your 3 choices have cons, at least one of those 3 most probably doesn't have 1 con as bad as your EZ36.
All I can wish for you is that either the issue never comes back or you swap engine and never have big issues again. In the end it's all a matter of the efforts you put into it but there comes a point where you want to stop pouring efforts and start driving for a long time.

You are patient that's for sure, you need that for those builds anyway!