John's EZ36R H6 818R Build

[Frank818]

You're totally right, I think I mixed the numbers and whp vs hp thing.

So 254hp would have been what the dealer said when you bought it new. Yeah 30 more makes a difference!

[Hobby Racer]

One thing that bothered me on my first track day with the new 6 speed compared to my old 5 speed was how badly it would shift from 4th to 5th and back into 4th. I would have a hard time getting it to go into 5th and when down shifting I would sometimes end up in 6th. Not an ideal situation on a race track. I did some investigating at the track and determined there was some binding in the for /aft bell crank (the top one) I fabricated that was making shifting hit or miss. Since I was unable to fabricate a fix at the track, I just lived with it until I could get home to my shop.

After tearing the previous shift mechanism apart I found wear marks from interference of the top bell crank with the support structure. This would need to be addressed. Instead of making a simple standoff, I redesigned the whole thing to be smaller, lighter and more rigid, with a better geometry for the shift forces.

Here is the old setup.

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The old setup connected both the forward and backward motion with the twisting motion of the shift shaft at the tip of the lever arm that mounts to the shift rail. In the new design I separated them back to what Mechie had done on the original bell crank design. I also enlarged the top bell crank to add rigidity and used a larger bearing to more evenly distribute the load. Finally I angled the top bell crank to put the forward and backward forces directly in-line with the shift shaft.

Here is the new setup.

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Now its back to Watkins Glen in two weeks for more testing and hopefully some quicker lap times

[Rob T]

I see the reverse lockout mechanism, also. My 4th-5th shift was horrible until I got that sorted. The shifter drifted out past 5th to neverland....

I am envious of your machining and design skills. Awesome....

[Hobby Racer]

I see the reverse lockout mechanism, also. My 4th-5th shift was horrible until I got that sorted. The shifter drifted out past 5th to neverland....

I am envious of your machining and design skills. Awesome....

Thx Rob. The new to me milling machine is a ton of fun. Makes you want to fabricate things just to use it

[aquillen]

Thx Rob. The new to me milling machine is a ton of fun. Make you want to fabricate things just to use it

I'm in with that. Your shifter setup is top drawer.

[Frank818]

Awesome bell crank pieces! I wish I'd do the same one day!

[Hobby Racer]

[DSR-3]

Just 1?

[Hobby Racer]

Just 1?

Just one. Its a Rotrex C38-91 centrifugal supercharger (not a turbocharger). Its rated to support between 350 - 720 hp. I am only shooting for ~400 at the crank. My calculations put me in the sweet spot of the compressor map at about 67k rpm for the compressor wheel, and that's with the largest pulley they make! I can step down the pulley size to make much more power in the future if needed.

I'm in the process of deciding what size/shape inter-cooler to use and just how much bigger my fuel injectors will need to be. One thing I am sure of is that I will need a complete rebuild of the engine first to add a completely new forged rotating assembly to handle the increase in power. The EZ36 weak links are the crank, rods, and pistons in that order. Outfrontmotorsports reports they break stock cranks at only 8-10 lbs of boost.

[Hobby Racer]

To make any real power over stock in an EZ36 engine you need to strengthen the bottom end. That means a stronger crank shaft, stronger rods and stronger pistons. The rub is that there are no aftermarket parts for the EZ36 available. However you can de-stroke an EZ36 using a modified crank shaft from an older Subaru EZ30 flat 6 engine. This necessitates also using custom forged straight rods. Not asymmetric ones like the stock one's are. And finally custom forged pistons.

When your all done you end up with a 3.2 liter higher revving, much stronger engine. This setup was pioneered by Outfrontmotorsports I think. At least they are the only ones I've seen talking about it. They offer the required parts to pull this off.

Once the engine itself is built up to handle more power it becomes a complex game of tetris, fitting in all the needed components into an already tightly cramped engine bay. But, I think I have it all worked out. I have been using wooden and cardboard cutouts to see if I can get everything to fit and get sufficient cooling.

[Jetfuel]

Racer, can we count on you to document this engine build???

Jet

[Hobby Racer]

Racer, can we count on you to document this engine build???

Jet

Yes, figured I've blazed a few trails already, might as well do a few more

This car is going to be so fun!

[Sgt.Gator]

Wow. The point of going H6 for me would be to eliminate the turbo and intercooler!
This should be interesting!

[Hobby Racer]

Wow. The point of going H6 for me would be to eliminate the turbo and intercooler!
This should be interesting!

Actually its a supercharger. I like the linear power and instant throttle response compared to a turbo, especially coming out of the corners.

The NA motor is great and has plenty of oomph for most tracks, but my home track of Watkins Glen is long and fast. I hit 140 mph on the back straight and those dam Porsche GT3's are still climbing up my back side! I can hang with them in the brake zones and corners but not on the straights.

Time for more power

[Sgt.Gator]

How is it going to mount? On the LGT forum there have been a few Raptor Superchargers installed in Legacys, but they hang so far off the side I was under the impression there would not be room in an 818.
Are you going to intercool it?
Gallery_Subaru_Liberty-Liberty-4GEN-H6-3-.pngGallery_Subaru_Liberty-Liberty-4GEN-H6-3-2.pngGallery_Subaru_Liberty-Liberty-4GEN-H6-3-5.png

[Hobby Racer]

Thought I'd get a jump on things before Turkey day. I was able to get the engine and transmission out as one unit without removing the rear suspension or half shafts!

I will be cutting out those angled bars and making them removable as many others have done to make this job easier in the future. I want to be able to remove/install the engine and transmission fully dressed, including the exhaust by just lowering everything into place.

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[Hobby Racer]

How is it going to mount?
Are you going to intercool it?

I'm going to mount it where the blue circle is, just to the left of where the power steering normally goes. Now that I'm looking at the engine out, I might try mounting it were the red circle is. Looks like there might be just enough room and there is a mounting bracket already available since that's where the AC compressor normally goes. Only problem with that spot is that the air inlet would need to be routed under the plastic intake manifold runners where on the left side its wide open.




The intercooler will be mounted above the transmission where I previously had my transmission cooler. It will be cooled by air ducted in from both side vents running through twin 4" hoses connected to a custom plenum to force all the air through the core.

[DSR-3]

What a fun project!
Maybe consider pulling all of it off and positioning the blower where you want, then the alternator wherever it fits.

[aquillen]

These cars don't need all that much alternator. I stuck in a Geo-Metro/Honda unit that is probably 2/3 the size. Made different mounts of course. But would give you a lot more room to play. Would need to review the ECU to alternator control circuits though - could run into a problem there.Then again I need to re-read your thread above on ECU as I'm expecting you can't use the OEM = put whatever you want for alternator. Car is going to be a total blast with the blower in there. Envy envy envy.

[Sgt.Gator]

I hadn't thought of the LGTs requiring power steering and keeping their AC units, my bad. Yes, I'm sure you can find a space to fit.
However as you mentioned the 36 is not a good candidate for more than 7psi of boost unless you rebuild it pretty dramatically. John at Outfront says the crank breaks at 8psi, so now you need a custom crank too. You may be better served building an EZ30 and selling the 36. The parts you need for built EZ30 are on the shelf and the work is well documented.
I think the 36 is a great motor for an NA 818, but the 30 is better for Turbo/Supercharging.

[Hobby Racer]

I hadn't thought of the LGTs requiring power steering and keeping their AC units, my bad. Yes, I'm sure you can find a space to fit.
However as you mentioned the 36 is not a good candidate for more than 7psi of boost unless you rebuild it pretty dramatically. John at Outfront says the crank breaks at 8psi, so now you need a custom crank too. You may be better served building an EZ30 and selling the 36. The parts you need for built EZ30 are on the shelf and the work is well documented.
I think the 36 is a great motor for an NA 818, but the 30 is better for Turbo/Supercharging.

I thought about that hard and long. But if you build an EZ30 you still need better rods and pistons to add boost. So the only additional cost to build the EZ36 is the stronger crank. Since you can use a modified EZ30 crank its really not that much more expense, plus the EZ36 has these advantages over the EZ30.

1. Better internal cooling system
2. Better oiling system
3. More cubic inches (3.2 liter after destroking)
4. Better OEM parts availability since they just stopped making them in 2019. EZ30's have not been made since 2009

The only real advantage I can see in building an EZ30 is the variable lift system on the intake cams. But that also adds complexity to the valve train.

Besides, I really like a challenge

[Sgt.Gator]

I know one of the other criticisms of the 36 is the rod ratio, but if you destroke it that may fix that issue. Do you watch the German Subi Performance You Tube Channel? He's building an awesome EG33. I love his shop and channel but lately most of his videos are in German. For awhile he was doing about 50% of them in English.
Here he compares an EG33 to a EZ30:

Good Luck!

[Hobby Racer]

Yes I used to watch that channel a lot. But since they have been all in German lately I have not been watching. He likes the EG33 because its basically an EJ motor with two extra cylinders.

[Hobby Racer]

Supercharger arrived today! Started mocking up the location using wooden brackets. When I am pleased with the fit I will machine one out of 3/8" aluminum plate.

It looks like it sits high in the pictures but the unit sits below the level of the rear deck. The outlet to the compressor will turn 90 degrees and head back to the intercooler. I cut the diagonal support bars out to make it easier to test fit the engine / trans. I will design a nicer one piece triangular brace that bolts in for easy removal later. I am re-purposing the old power steering bracket as the base for the supercharger support. It now supports the alternator and the factory belt tensioner just like the OEM setup, win-win!

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[Hobby Racer]

In order to get the pulley alignment correct with the alternator and crank I had to mill 0.212" off the face of the power steering bracket. That also gave me a perfectly flat surface to mount the new supercharger bracket to.

I am thinking of welding the supercharger bracket to the power steering mount for added rigidity. I will also add some gussets to the back side to prevent flexing. I may mill out some of the material in the center just to make it look nicer.

I think I just like playing with the mill.

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[Sgt.Gator]

Does the supercharger belt go around the crank pulley ring that is for the alternator/power steering and share duty with the alternator, or is it on it's own around the A/C ring, or a mandrel off the front?

[Hobby Racer]

Does the supercharger belt go around the crank pulley ring that is for the alternator/power steering and share duty with the alternator, or is it on it's own around the A/C ring, or a mandrel off the front?

I put it together quick to show the belt path. The red arrow shows the belt direction. I set it up to use a shared 6 rib serpentine belt for everything, just like the OEM setup. The mounting bolts you see coming close to the belt path will be countersunk cap screws when completed, just like what I'm using to secure the supercharger. This setup gives me more that 180 degree of belt contact for the crank and supercharger and about 160 degrees contact for the alternator.

[Mitch Wright]

Looks like one more countersunk bolt and you will be golden.

[lance corsi]

Does anyone make a roots style blower for these?

[Hobby Racer]

Does anyone make a roots style blower for these?

No one makes a roots style kit that I've been able to find, but you could certainly adapt a roots blower to fit. The biggest hurdle would be making a new manifold to bolt up to the blower since they usually sit between the cylinder banks. Hey, maybe Art Quillen can make you one up in carbon fiber.

[lance corsi]

I’ve already made mine, but thanks. I’m sure Art’s manifold would look better tho.
I once considered building my system like that, considering all the piping work involved in a turbo setup, it’d be easier. But I enjoy plumbing work. I like the way a nice set of headers looks. I enjoy hearing the sounds emitted from a turbo, blowoff valve, etc. personal preference.

[lance corsi]

With a blower, I’d think a dual exhaust would be a no-brainer.

[Frank818]

I love challenges! Can't wait for 1st engine run already! Go for it, Hobby!

[Hobby Racer]

Finished up the fabrication of the supercharger support brackets today.



I did however hit a snag. The first time I finished It was beautiful and artistic. However, I neglected to test fit the part to the engine before finish welding everything up. This of course bit me in the butt. The diagonal support brace I welded in for extra strength hit one of the intake manifold runners and prevented the bracket from mating to the block properly.

You can see the original weld point circled in red. The second try circled in blue now clears the intake runner. At this point I was tired and not in a mood to mill out a pretty dual arm support, so I went with the simple yet function straight piece of aluminum.

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Once fitted to the engine everything lined up very nicely. The supercharger nestles down in the support brackets and is quite rigid.

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[Hobby Racer]

Just in time, my new engine internals arrived from Outfront Motorsports.

• Custom forged pistons from CP-Carrillo
• Custom forged H beam rods from Molnar
• New and modified EZ30 crankshaft
• 12mm head studs by ARP

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Now I guess its time to tear this thing apart!

[Hobby Racer]

I thought I'd let you know all the different parts that are coming together for this build. It's a strange mix of different Subaru OEM parts from different motors and some custom aftermarket parts.

EZ36 (3.6L) + EZ30 crankshaft (3.0L) = EZ32 (3.2L)

• EZ36 block bored out 0.25mm (92.25mm bore)
• Custom CP-Carrillo pistons 9.7:1 CR (92.25mm)
• Subaru OEM piston rings from an EJ205 (02-05 WRX)
• Modified aftermarket rods for a Subaru EJ25 non-turbo engine (thinned on the big end)
• Rod bearings that fit an EJ257 (04-07 STI)
• EZ30 crankshaft machined so the EZ36 oil pump gear will fit on the nose

Wow, can you belief all the disparate parts that go into making this build work!

[Mitch Wright]

Sounds like fun to me.

[Sgt.Gator]

Is Outfront building this engine for you as a complete shortblock? We (Colonel Red Racing & Arcflash) do a lot of business with them, great folks. They have my trashed engine from the nut sticking in the cam now.

[Hobby Racer]

Is Outfront building this engine for you as a complete shortblock? We (Colonel Red Racing & Arcflash) do a lot of business with them, great folks. They have my trashed engine from the nut sticking in the cam now.

No, I'm building it myself. I just sourced the parts from them.

[Hobby Racer]

I've been working with Rot T and Mitch Wright to setup a track day at VIR where forum members get a 20% discount!

We will be "tagging a long" with a normally scheduled NCM event.

Please join us for 2 great days of racing and fun.

Check out the information in the General Section of the 818 forum here.

I would love to meet everyone in person.

A special thanks to Mitch for hooking us up with the discount!