dpkilty's EJ25 powered build log

Follow progress of your fellow builders. Pictures encouraged!
dpkilty
Posts: 223
Joined: 27 Jan 2014, 20:13
Anti-spam question: 4
Are you a spammer: No
Location: Indiana, USA

Re: dpkilty's EJ25 powered build log

Postby dpkilty » 17 Nov 2015, 09:47

I figure I'll ask this here to get the discussion going, and if it ends up getting good info going I can make a separate thread for it in a more appropriate place...

Since I am being all weird and still planning on using a Subaru motor and gearbox I have been trying to figure out the whole custom axle into a Miata upright thing.

But as luck would have it, the stock wheelbase of a Legacy (which uses the same transmission I have) is the same as the rear of the Midlana. So I could use stock axles. So I'm faced with a possibly cheaper option...

How much work would it be to use Subaru uprights instead of Miata uprights in the rear?

Problems I foresee:

1. Obviously the rear suspension geometry is pretty much shot. I need to plot everything out and see just how different the two uprights are. <--- THIS IS THE BIG ISSUE
2. Mismatched wheel lug patterns front to back. I guess its not the end of the world since wheel sizes are staggered but my OCD might kick in and bug me.
3. E-brake assembly would have to come from a Subaru as well, might not be too big of a deal.
4. Brakes in general, front and rear would be completely different... That is unsettling as well.

Just thinking out loud here, but I guess I could always use Subaru uprights in all 4 corners...

I decided to go the Midlana route since the suspension geometry was already figured out. It seems like the Subaru uprights could negate that fact altogether.

Or should I just pony up for custom axles and be done with it?

Midlana1
Site Admin
Posts: 2708
Joined: 19 Dec 2008, 16:44
Anti-spam question: 4
Are you a spammer: No
Location: Southern California

Re: dpkilty's EJ25 powered build log

Postby Midlana1 » 17 Nov 2015, 11:26

You're summation is correct; you'd have to get the uprights, carefully measure them, then figure out what geometry will fit and give decent camber control, without bumpsteer.

Wheel lugs, meh, like you said, the front and back wheels may well be different anyway. If all four wheels are the same model, no one will ever know.

E-brake... different... but not. It's still a lever and a cable, so it's pretty much the same regardless.

Don't worry about the brakes, that's handled by the proportioning valve/balance bar.

Bottom line, no one can tell you how to spend your money; you'll have to decide whether $800 axles balance out the extra work. It'll take weeks or months to figure out the suspension geometry; it all depends on whether you view that as a fun task or a nightmare.

dpkilty
Posts: 223
Joined: 27 Jan 2014, 20:13
Anti-spam question: 4
Are you a spammer: No
Location: Indiana, USA

Re: dpkilty's EJ25 powered build log

Postby dpkilty » 16 May 2016, 08:05

Picked up the rest of the needed Miata parts this weekend. Rear hubs, ebrake assembly, and complete brake setup.

I now face a decision... Do I wait to cut metal until I have the seats in my possession or do I start laying things out now? I know I am using 2 Kirkey seats, a 15" for me and likely an 18" for the passenger. That way I can hopefully accommodate various passenger sizes.

I guess I should wait as I don't have the motor to put in place either.... But I do have transmission case halves for mock up.

I'm not in a huge hurry to complete this project so it would probably be best to wait and not cut anything yet just so I don't waste anything.

So in the meantime I'll likely depower the stock steering rack, clean up the spindles, replace the wheel bearings and wheel studs, remove the dust shields from the rears and look into getting a seal kit to rebuild the calipers.

One thing I have been kicking around is since I am going to be running an air to water intercooler I'd like to also run an icebox. Trying to find a good place for that is kind of tricky. I am debating switching to an outboard suspension setup to try to free up room for the icebox. I originally wanted to run inboard suspension because it looks cooler and that was pretty much it. I know the outboard is simpler, cheaper, and easier so it may be better to just switch anyway.

Midlana1
Site Admin
Posts: 2708
Joined: 19 Dec 2008, 16:44
Anti-spam question: 4
Are you a spammer: No
Location: Southern California

Re: dpkilty's EJ25 powered build log

Postby Midlana1 » 16 May 2016, 08:49

With many parts you can proceed without, but the seats are such an integral part of the car, I vote for waiting. It's not just the seat width but the lean-back angle, as it very much affects how where they mount and where your feet end up. Regarding the engine, because it's a significantly different drivetrain, I'd wait to have that on-hand as well, because basically you're going to build the rear part of the car around it. FWIW, if someone's got a blown up engine you can get for free, that's all that's needed for mock-up.

dpkilty
Posts: 223
Joined: 27 Jan 2014, 20:13
Anti-spam question: 4
Are you a spammer: No
Location: Indiana, USA

Re: dpkilty's EJ25 powered build log

Postby dpkilty » 16 May 2016, 09:08

I am keeping my eyes open for a blown up motor, but with the nature of Subaru, even blown up motors go for a pretty large amount sometimes. There are work-arounds, but still.
I did grab the case halves for dirt cheap for mock up just because. I would like to do the same with the motor too but we'll see what happens.

I have a pedal box assembly and the steering stuff I can mock things up with too but those are all things I can deal with later. I have them if I need them but I'd rather use "final product" stuff there anyway. It just makes more sense to me.

dpkilty
Posts: 223
Joined: 27 Jan 2014, 20:13
Anti-spam question: 4
Are you a spammer: No
Location: Indiana, USA

Re: dpkilty's EJ25 powered build log

Postby dpkilty » 09 Sep 2016, 06:37

In the wake of Kurt's issues fitting a large intercooler on the car I have been looking at my own setup very carefully.

Subarus are TMIC from the factory, but the hood scoop draws in a lot of clean cool air. In a mid engine setup obviously that is an issue.
Lucky for me Factory Five made an 818... A Subaru powered mid engine kit car. So a lot of guys are fighting the same issue. Their general consensus is that for most street driven setups a TMIC with some ducting is good enough. But anybody wanting more than 300 hp or that will be in any kind of motorsport is going AWIC. I have been leaning that way too. I can piece together a good setup for only a couple hundred dollars more than a quality TMIC setup.
My issue is this:
1: A lot of guys are running a cheaper Bosch electric water pump used by Ford on some OEM applications. Its an 8gpm pump. But those applications aren't usually continuous duty. The pump cycles on and off to circulate the water from what I can tell.
I plan on using a much nicer electric water pump rated for continuous duty, but it pumps 20gpm. I am concerned I will be pumping the water too fast for the radiator to cool it back off. I do plan on having an ice box of sorts but that is more for short term runs like autocross and such. I do want to have a decent amount of water in the system to avoid heat soak as best I can in that aspect.
2: I plan on using a radiator from a Honda Civic (or similar) just to cool the water in the AWIC system. So I will have 2 radiators in the car. I am thinking about mounting it behind the driver on the side (in front of the rear tire). I had planned on using the passengers side for air intake and having mesh there instead of body panels anyway. I'm uncertain how much air I will be able to pull through the radiator even with a shroud and fan mounted to it. A little duct work might help too I guess...

Research has shown me that a lot of the mid engine setups using AWIC for road racing do fight heat soak. There are 2 ways to handle this, 1: add more water, and 2: Increase the radiator efficiency (either by larger radiator or more passes etc.) So I am trying to get a fairly efficient setup from the start. If I have to upgrade the radiator later ok, that is why I chose one that will have aftermarket options.

Midlana1
Site Admin
Posts: 2708
Joined: 19 Dec 2008, 16:44
Anti-spam question: 4
Are you a spammer: No
Location: Southern California

Re: dpkilty's EJ25 powered build log

Postby Midlana1 » 09 Sep 2016, 07:44

Wait, if you're thinking of putting the radiator out the side in front of the rear tire, forget that and put the intercooler itself there. Bam, fixed!

dpkilty
Posts: 223
Joined: 27 Jan 2014, 20:13
Anti-spam question: 4
Are you a spammer: No
Location: Indiana, USA

Re: dpkilty's EJ25 powered build log

Postby dpkilty » 09 Sep 2016, 08:24

Doing that will result in the intake piping being close to 6-8 feet long instead of around 16-18 inches. Its common for guys to run FMIC setups on Subarus. It isn't real helpful on small turbo cars. I fall squarely in the small turbo realm.

The stock location turbo on the Subaru is basically behind and above the passengers side valve cover. I could run a custom header and mount the turbo low in front of the crack pulley and run the intercooler in the "fender" location but then I'm looking at a turbo being inches away from the gas tank and my back, not to mention the custom exhaust work.

Another case of "six of one, half dozen of another" ... :|


of course another option is mounting the cooler up front with the radiator...

big_wasa
Posts: 45
Joined: 05 Dec 2013, 11:34
Anti-spam question: 4
Are you a spammer: No
Location: Spalding Uk

Re: dpkilty's EJ25 powered build log

Postby big_wasa » 10 Sep 2016, 02:19

I plan on running a charge cooler setup. I figure the pipe work to the front rad will help increase capacity.

dpkilty
Posts: 223
Joined: 27 Jan 2014, 20:13
Anti-spam question: 4
Are you a spammer: No
Location: Indiana, USA

Re: dpkilty's EJ25 powered build log

Postby dpkilty » 12 Sep 2016, 06:10

big_wasa wrote:I plan on running a charge cooler setup. I figure the pipe work to the front rad will help increase capacity.


That's exactly what I had in mind after I though about placing the HE in front of the radiator.


Return to “Builder's diaries”

Who is online

Users browsing this forum: No registered users and 1 guest