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DRProjectCentral New Reader
10/30/23 12:17 p.m.

Made a little more progress the other day. Dropped the gas tank and set it aside for the possibility of reuse. Also shoved the engine underneath and set the NB chassis down...what a squeeze. This isn't where the engine will live (it's still way far forward) but at least we could identify a few possible issues. As it stands, I'll still be keeping the AC compressor (and fighting for it tooth and nail until I inevitably lose). The rails will likely need notched, but that's an issue for another day.

The current plan is to cut the entire front frame, some firewall, undercar framerails, trans tunnel, and rear frame out as one big unit. It may result as some people have mentioned above that the entire Miata spine ends up in the Fiat, with a little wheelbase adjustment. At the moment, the big consideration is the roof frame: in the Miata, it nicely folds up way up high. In the Fiat, it takes up a little space on top of the backseat. The entire backseat area will be gone, but I also need to pay attention to where the rear quarter windows fold down. Lots of ideas floating around.

DRProjectCentral New Reader
11/14/23 9:02 a.m.

Update from over the weekend: finally got everything stripped out to start cutting the body up, and although I adamantly wanted to keep the Fiat unibody intact, I've decided to suscumb to Mazda's engineering and switch the entire Mazda floorpan and other bits into the Fiat. The wheelbase will need to be extended .55".  As far as I'm concerned, the newest Fiat 124 Spider is just an ND Miata with a different engine, which is exactly what I'm up to. This weekend I'll break out the plasma cutter, plus I get to start planning engine fitment and drivetrain specifics. Photos to come over the weekend!


For those interested in the Pentastar aspect of this, I also yanked the rotten, disgusting, gross, rediculous oil filter housing out over the weekend. I'll be custom-building a delete plate to allow me to run a traditional spin-on filter with a REAL oil cooler mounted elsewhere. Baxter Performance makes adapters (one for a spin-on and one for remote mount) but those spin into the existing housing. I'll keep that project updated as well.

DRProjectCentral New Reader
11/25/23 9:44 a.m.

Got the NB mostly cut up yesterday. Of course it needs some more trimming, but the major structure needed is exposed and can be measured/moved. The next phase is setting up the engine/transmission in the front end and seeing if it can stay low enough to clear the fiat hood...but we'll see. Anybody need some rust-free NB quarter panels?

JBinMD New Reader
11/25/23 12:23 p.m.

If the wheelbase difference is only .55" I would probably just split the change 1/2F:1/2R and ignore it since it wouldn't really be noticeable.  And if you do decide to stretch the wheelbase that much then it's probably easier to move the front suspension mounting points forward on the subframe, or the subframe-to-chassis mounting points, than any other way.  

11/25/23 12:47 p.m.

Half an inch difference will be cosmetic, Easy button will be to reshape the outer wheelarch/opening to compensate. Moving the front or rear axles is a boatload of work.

DRProjectCentral New Reader
1/7/24 7:42 p.m.

Finally made some progress now that the holidays are over. Fabbed up these static shock replacements, with plenty of adjustability to set the ride height while the motor and body get mocked up. A nut welded to the top of the threads protrudes from the top, so no disassembly is required to change the height.

Manual_Trans New Reader
1/9/24 12:57 p.m.

This is an interesting build! I'm curious to know what your plans are to squeeze out some more power from the 3.6. I think they're actually pretty cool motors and given how many of them have been produced, parts are dirt cheap and they'll eventually be a dime a dozen in wrecking yards. 

My DD/kid hauler is a 2018 Journey with the 3.6 in it and it has basically zero aftermarket support (unsurprisingly). I got bored a while back and ordered a ported TB for it just for fun. I did a bunch of reading and found the MMX TB to be highly recommended. To my dismay, turns out it was ported up to the plate on either side, but the plate itself remains the stock circumference. It's supposedly still good for a bump in performance, but I'm pretty skeptical. I haven't installed it yet, so I can't comment on any noticeable difference. 

DRProjectCentral New Reader
1/23/24 3:33 p.m.

In reply to Manual_Trans :

I'll give you the quickest rundown I can. There's a site, pentastarv6performance.com, that has the master list, but it's going down soon. Also the Pentastar V6 Performance group on facebook. Anyway...

Throttle Body: You can go ported, or you can adapt from a 5.7 Hemi with a harness from MMX. As far as I know, only the Hemi TB is truly 80mm. I will be using a Hemi, but I'm also making my own upper intake if I can't find a short enough one to fit under the hood.

PUG Lower Intake: The lower intake manifold from a 2018+ PUG engine flows better than the standard lower intake. Direct fit, even though the parts guides don't say so. I will be using this if I don't have to make my own intake.

Spark Plugs and Coil Packs: People keep going back and forth on these, but a dyno shootout on a 2015 200S AWD showed no significant gains by simply swapping coil packs or spark plugs. I'll be sticking with Mopar OEM (no performance improvement, just telling you for reference). For spark plugs, ues whatever you prefer or Mopar recommended.

Intakes: I'll be making my own (duh), but the usual suspects produce these (Mopar, K&N, Spectre, Volant). Pick your poison. On my 200S, I found a discontinued Mopar intake: it's the only one that completely repalces the resonanace tubes. I love it.

Exhaust: The usual suspects.

Lightened Pulleys: These were made in irregular batches, so you have to find them used. Lightweight aluminum alternator and crank pulleys were both produced. I will not be using these, because they're rare and expensive and I don't want the jewelry look.

Tuning: This is the primary factor in performance for these engines. It's possible to squeeze another 30-40hp out of them NA: the cam profiles are incredibly tame for emissions purposes. A quality transmission tune in the Nag1, ZF8, and ZF9 go a long way and are the most effective. I will be getting a tune, but the situation for this project requires it anyway.

Forced Induction: Various companies make superchargers (Edelbrock/Magnusson/RIPP), especially for Jeeps and Challengers. There are also some one-off turbo setups out there. The most power I've heard of is in the 600hp neighborhood, but the tune has to be perfect. Otherwise, you're blowing head gaskets and trashing pistons. No cranks or rods have busted yet, and the bore is the same as a 4.8/5.3 LS. Maybe someday we'll get strengthened pistons. I have routinely heard of 450ish power at the wheels (dyno-proven) with quality tuning. Once/if I go forced induction, I'll be targeting 450 crank hp. That'll be plenty for a 2,500lb car.

Your biggest barricade is the 62TE in your Journey. The 3.6 is pretty close to maxing out that trans's potential as is. I'm not sure if it's tunable or not, but I would hazard your best bet to be an engine/trans tune that simply changes the behavior of the powertrain to be snappier.


DRProjectCentral New Reader
1/23/24 3:35 p.m.

I promise I haven't forgotten to post in here, gang. As it turns out, planning a wedding takes more work than i thought. If I make my fiance wait any longer, she'll leave me!


Just kidding, of course, though that would give me more time to work on this thing...

Shavarsh HalfDork
1/23/24 4:09 p.m.

In reply to DRProjectCentral :

I'm running the same "parallel project" haha so I can relate to this post!

DRProjectCentral New Reader
1/27/24 4:29 p.m.

Made a little progress today: I have a new oil pan from a 200/Cherokee on the way, which will help with K-frame clearance...I hope. I'll be test fitting it, but if it doesn't work, I'll have to get creative with a custom pan. The sticking point there is the oil pump way up front, right where the steering rack lives. So either the engine will be sitting significantly far back, or I'll have to get extremely creative with how I chop up the cradle. As it stands, at ride height, the oil pan will hang about 3 inches lower than the cradle: a big armor shell is a priority.

Anyhow, an early test fit showed the necessity to cut the framerails out as shown here, to clear the heads and keep the engine back. I also set the floor height fairly close to where my 78 Spider rests: adjusting that will come later.

DRProjectCentral New Reader
2/4/24 8:50 p.m.

Drained the oil out of the motor to determine where the oil pump lives and how it will want to sit amongst the steering rack. Wouldn't you know, they want to occupy the same space at the same time (and as SuperFastMatt says, occupying the same space at the same time is hella illegal). I've determined that, no matter what, the minimum required depth for the oil pan is equal to the lowest point of the transmission pan, for ground clearance reasons. So the whole shebang will have to sit higher than I anticipated, and therefore some of my anxieties about mounting this thing have been relaxed.


Some of them, not all of them. Because I have to get the powertrain up higher anyway, the factory intake (and all other factory intakes I've found) will absolutely, no question, without a doubt, stick up higher than the hood. My worst nightmare has become real. The only solutions to this problem are to either make a lower profile intake manifold...or cut the hood. It's currently seeming like adding some elevation to the hood will be the most appropriate solution (and one that will allow the addition of a twin-screw supercharger, if I still decide to go that route, although at that point I'd have to make sure the hood bulge isn't excessive).


For your number crunching pleasure, the height from the floor to the underside of the Fiat hood (from my '78, which is at the correct ride height), is 32". This engine, in its current configuration (2014 Chrysler 300 RWD), is 31.5" tall to the top edge of the throttle body. The shortest combo I have found (oil pan from a UF 200, upper intake manifold from a Pacifica/later Promaster) would save me 1.875" inches at the pan and a whopping 1/2" up top. If I make my own oil pan that just barely clears the pump, I'll gain another inch for steering rack clearance, but nothing is guaranteed. The silver lining to all of this is that I still have 3" of transmission tunnel above the 845RE bellhousing.


Anyway, here's an image of the big dumb monster sitting on a pallet under the NB chassis set at ride height. I still would rather have this over an LS, or a small block Ford, or a Honda, or...

Shavarsh HalfDork
2/5/24 1:23 p.m.

That's a great image. Are there any rear sump configurations available? Asking for a friend...

DRProjectCentral New Reader
2/5/24 1:30 p.m.

In reply to Shavarsh :

Rams, and later Durangos/Grand Cherokees have rear sumps, but they're still too deep for my application. Which is a bummer, because they appear to be very shallow up front (just enough to clear the oil pump). If the oil pan I picked won't work, I'll be making my own

DRProjectCentral New Reader
2/8/24 9:54 a.m.

A rare weekday update: make sure you take all your bolts out. Double check, gang!

Swapped out the existing two-piece oil pan for a one-piece from a 200/FWD Cherokee. It seems excessively deep, but it actually lines up with the bottom of the transmission pan. As far as ground clearance is concerned, there's no reason to go any shallower (and I could only go another inch, maybe, because of the oil pump). External pumps aside, it just feels good to keep making some semblance of progress.

However, in the meantime, it turns out those rubber plugs under the back of the pan were NOT, in fact, simple drain plugs. They covered the entrance to the rearmost mounting bolts (not dowels, what do you know?) between the oil pan...and the rear main seal retainer. As it turns out, a little prybar can rip the bolts right out of thin sheet metal if you don't look as thoroughly as you should at why the pan won't drop. 

Add that to the list. At least it's not a massive priority, since the engine still needs gone through anyway and isn't permanently mounted in the car.


Anyway, the engine was set back onto the pallet with 4.5" of clearance under both pans. I dropped the body back around it at as close to measured ride height as possible. It sure is a funny look with so much engine hanging low in there: so low, the oil pan will hang under the suspension crossmember. I'll still be needing a skidplate. The hood will need to be modified as well...which I have a plan for, but some rendering will need to be done so I can visulaize a few options before I start cutting up a pristine large hump hood. 

malibuguy HalfDork
2/8/24 11:55 a.m.

ill admit...the title of this thread made my head tilt like a dog hearing a high pitched sound.

I dig it


DRProjectCentral New Reader
2/14/24 10:51 p.m.

Sometimes, forward progress comes as a result of hours of discussions as opposed to wrench turning. After I cut out a cardboard template to prep for cutting up the firewall, my dad noticed that the engine would be mounted so far back that it would practically be interfering with the windshield. After some deliberation, we came upon a few possible solutions: feel free to chime in so I don't get myself killed driving this thing.


1) Fab up a custom oil pan and pickup that allows the oil pump to hang in front of the steering rack, while keeping the engine as low as possible. Pros: the rack doesn't move and I don't have to cut the firewall. Cons: radiator and A/C condenser fitment will be a chore (I haven't given up on A/C!), the engine will sit significantly far forward in the chassis, and I would have to add a monster hump to the hood to clear the intake, even if I make a low-profile one.


2) Swapping the spindles side to side was discussed. This would be accompanied with picking up a rear-steer rack and making a new oil pan of course, but introduces some issues. We determined the best course of action here would be to use a new rack with the exact same width as the Miata rack, moved rearward the exact same amount as the spindle arms would be. However, because the spindle arms would now be angled downward a smidge instead of upward, would the rack need to be lowered to keep bumpsteer and Ackerman under control? Raised? Left alone? Pros: The engine can sit in a more ideal location, I won't have to cut the firewall, and I'll have more space up front for the radiator and whatnot. Cons: moving the factory Miata rack seems like I'd be breaking some unwritten rule. I'm not smarter than Mazda.


3) Switching to an external oil pump would be a possibility. HPTuners can turn off the variable oil pump solenoid monitoring. Because the Pentastar oil pump "fails" in high pressure mode, theoretically I could toss the pump, route the pickup to an external pump, feed oil into an external filter, then back into the block up top like normal. I can test this by unplugging the pump solenoid connector in my 200 daily, but I don't want to have to fix that if it goes sideways. Pros: the stupid pump is gone for good and the rack doesn't have to move. Cons: If losing the solenoid doesn't work like I'd be betting, all that work will have been for nothing. High risk, high reward. Also, external oil pumps are expensive!


Frankly, I'm hoping some serious research will lead me to realize that option 2 will actually work just fine, as long as it's implemented correctly. And no, for all you wise guys, I will NOT consider switching to a different motor. This thing is going into this car if it kills me! 


All progress is good progress, I suppose!


brad131a4 (Forum Supporter)
brad131a4 (Forum Supporter) Reader
2/14/24 11:16 p.m.

Oil pickup moved to the back and pan made to fit. That way everything is left as is. I would think there is someone around that can weld up the modified pan.

Shavarsh HalfDork
2/15/24 12:51 p.m.

Can you sketch where the rack wants to sit on the side of the oil pan (with ms paint or something) so we get a better idea of what is interfering? Option 2 sound like it will work, but I'm curious if the rack can just move down and a bumpsteer kit can make up for the change? I assume the oil pump is chain driven?

DRProjectCentral New Reader
2/16/24 7:43 p.m.

In reply to Shavarsh :

I'll get a sketch up at some point, but another poster pointed out that the axle stubs are offset. Flipping the spindles will screw up my caster behavior. Stay tuned though, I have another idea that may get the rear rack working. Stay tuned

DRProjectCentral New Reader
2/19/24 4:25 p.m.

After some thought, I devised this concept. Pardon my MS Paint illustration. Inspired by the factory Fiat 124 spindle, I can machine a bar that attaches to the existing tie rod location and 1 or 2 caliper bracket mounts. This bar will cross between the ball joint studs, then pass behind the spindle, where it will terminate at a chosen location in a rear-steer position. Because the bar is removable, I can machine a new one if the tie rod point ends up in the wrong place. This would add some unsprung weight, but so would poorly-chosen wheels. In the future, I can drill some speed holes through the bar to remove some weight. I would also need to source some longer caliper bracket bolts, obviously.


This is just a concept for now, but I feel like this would be a stellar solution to numerous problems, while allowing me to retain the Miata spindles, hubs, brakes, and suspension geometry. I would still need to source a rear-steer rack and make a new oil pan, of course. The only other issue is the back end of the control arm will likely want to interfere with wherever the tie rods end up, so I'll have to fab some clearance into the LCAs or get some tubular ones, but that doesn't concern me much. Hopefully this gets some traction and I can advance with putting the engine where I want it!


Edit: This is just a random spindle I found online in a forum somewhere.

DRProjectCentral New Reader
2/21/24 3:52 p.m.

I'm still pondering the DIY steering arms as laid out above, but I'm stuck on the best way to go about it. Cut out some 1/2" steel, bent over the ball joint, with a bent or welded tab to reach the caliper bracket holes? Machine the entire thing from a solid forged billet? Bent tubes with the appropriate flanges and ends welded for the tie rod to sit in? 


Considering this may need to be done multiple times until the tie rod position is finalized, I don't want to be out hundreds of dollars in R&D. But when it comes time to build this thing, I don't want an accidental tap of the curb to bend/break my steering arms...or a pothole at highway speed. I plan on building a backup set, just in case I'm far from home and need one on the spot.


What say you, hivemind?

fouckhest Reader
2/21/24 3:59 p.m.

Thoughts on using front suspension from another vehicle? 


I am doing something similar for my front engine/rear drive conversion 

DRProjectCentral New Reader
2/21/24 6:16 p.m.

In reply to fouckhest :

Not opposed, although I'm trying to keep everything suspension related as Miata as possible. No matter which direction I go, something is going to need to be custom built. This is at least reversible and tunable.

DRProjectCentral New Reader
2/25/24 11:03 p.m.

Still trying to make any kind of progress at least once a week on this deal. All progress is good progress. Today I pulled the front suspension back out and slid the motor back into place, if only to get an eyeball on where a rear-steer rack might live.

Pressed up to the firewall yielded this result. The firewall above the transmission tunnel will eventually be trimmed and moved back approximately an inch, to match the Miata's natural stepback in that spot. Because of the clearance required for some hoses and vent lines, the motor can't rest directly against the firewall: the resulting extra space means the bellhousing (almost) fits in the trans tunnel. In fact, it looks like there's enough space that I can actually SHRINK the tunnel a little bit.

Ironically, the oil pan I bought to try to clear the stock rack position isn't going to work, so back to Summit it will go. I'll be able to use my original front sump pan with the rack relocation, which will be fine until I get the time to make a new one: that pan will have maybe 3" of ground clearance AND jut out ahead of the front tires. I want at least 4" of clearance, so that project will come later.


As far as the steering goes, I'll need to break out the geometry calculations to determine the ideal mounting location and width of a new rear-steer rack and pinion. Obviously the goal is zero bumpsteer, but the space where the tie rod will pick up is going to be TIGHT. The control arm will need to be modified to clear the tie rods, and I may fab up a new caliper bracket to move the caliper up higher. We'll have to see. In the meantime, I chopped out the motor mount reinforcements in the subframe to make room for where the rack is going to sit.This is just a guideline, as the subframe is getting a little flexible and I haven't built any support bars yet. But as it stands, this is where the new rack is going to live. I'll be hunting for an NB Miata-width, rear-steer, manual or de-powerable rack on the cheap. But until I find one, the next stop is going to be reinforcing the subframe and getting some motor mounts set up.

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