I picked up an LS1 swapped Miata a few months ago and I am working on a few finishing touches to get the car to where I want it. The car does not have heat hooked up so this is my next project. The builder of this car attached two AN fittings to the water pump, AN8 and AN10. Does anyone know what the best way would be to run heat from these AN fittings? And then adapt them to the copper inlet and outlet tubes coming out of the firewall?

I also have a water pump that hasn't been modified. Would it be easier to install this and then run rubber hose as usual? Let me know your thoughts

 

First, 2 questions that are intertwined.
Would you prefer the AN fittings and braided hose over the normal rubber heater hose?
Do you prefer the simpler path of simply getting the heater hooked up and working or do you prefer to take the complicated course of doing the AN fittings and lines?

Looking at the under hood pictures it seems like the original installer intended to get rid of all the rubber hoses and make them AN and braided hose for the entire car.

You asked for opinions so here goes.

Just getting the heater up and running would be fairly simple.
Change out the water pump for one that uses the normal rubber hose connections then run the rubber hoses and check for leaks. If I were in your shoes and had bought a car converted by somebody else I would save myself a bunch of secondary headaches and take the simpler route.

If you want to do it right you need to address all the wiring and hoses under the hood, not just the heater hose.
Based on the couple of pictures it looks to me like the original installer did the minimum required to get the car up and running without doing the final steps to make the installation be nice and professional. Just take a look at the wires you can see in the middle picture where the covering stops well short of protecting the wire ends. In the third picture I can see an individual wire laying next to a plastic cover that appears to be protecting other wires.

Personally, my preference is to make the under hood stuff look as close to what you would see on a factory engine bay.
To that end on my installation I used the wire protector tubing to cover the couple of braided steel lines utilized to keep things looking stock because braided hose jumps out as being non-factory, just the opposite of what was done on your installation.

All that being said, if you want to finish the heater hoses as AN fittings and lines you will need to address the heater core ends by converting them to AN connectors.
The problem with dong that on the fire wall is available real estate.
The copper tubing comes out right near the back of the engine which does not leave much room to do AN connections and get you the 90 degree turn that is needed.
My guess is that could be the reason the original installer quit where he did.
To actually do it correctly my opinion is that the heater core end connections need to be moved from the driver's side to the passenger side in order to gain the real estate and get rid of the heater hoses laying over the top of the engine.
The problem is that you would have to remove the dash to access the area where alterations are required to do it.
V8 Roadsters makes a kit to convert the ends to AN and to move the firewall holes to the passenger side.
https://v8roadsters.com/product/heat-core-reroute/

Take a look at post #26 on my build thread to get an idea what it takes to do the change.
https://www.v8miata.net/general-moto...ag-3104/page2/
At the time I did not know about the V8 Roadster kit and so I simply went to Lowe's and figured up a copper tubing setup to get the job done but the process is very similar using the V8 Roadster kit.

It all boils down to how much time and effort you want to take to get the heater working and how "professional" you want the end product to be.

 

I appreciate all of the advice BGordon. To answer your first question, I would prefer the AN fittings and braided hose over the rubber hose because I feel like that would tie in with the rest of the install better. I looked at the V8 roadsters convert kit and that looks like a good route to go in order to connect to the heater core ends.

This brings up another question though. This motor was installed with the boss frog kit and from what I understand, this puts the motor considerably farther forward than with the V8 roadsters kit? I may have enough room to convert the heater core ends to AN without moving them to the passenger side? I should probably reach out to V8 roadsters and get some measurements to see if it will work. If I can't get it to work on the driver side, then I will probably go the alternate water pump and rubber hose route to save pulling the dash for now so I can get it going quicker. That could be a good project down the road when I have a little more time.

The wiring does need to be addressed and I plan on cleaning that up as you mentioned. Just a little work in that department should go a long ways and help protect the wiring. I appreaciate your attention to detail and really enjoyed reading through your build thread!

 

I took another look at your pictures and see what you mentioned about the engine being further away from the firewall.
You might very well have enough room.
Might be worth your effort to call up Jegs or Summit Racing and talk to a salesman to see about getting AN fittings that would connect directly to the tubing and do a 90 deg. turn.
Do a measurement but as best I remember both are 5/8" OD copper.
My engine is so close to the firewall I can barely but my fingers between.
No way does mine have enough room to do what you can do.

What are the other specifics on the drivetrain?

 

I did try the online chat with Summit Racing a few different times and we weren't able to get anywhere. I think I confused the guys more than anything. I will try giving them a call though and see if I can get in touch with someone who understands what I am trying to do here haha. I am hoping that I have enough room, but I will get some measurements back there the next time I get in the engine bay to see how much room the boss frog kit gives you; also to verify the 5/8" OD. I think you are right on that though.

It is a 90 with an LS1 out of 2000 corvette, T56 6 Speed, and a Ford 8.8 with an eaton truetrac. If you want to know any other specifics I could message you! I can hardly believe the amount of parts required to do this swap.

 

Has it been on a chassis dyno?
Mine has the same year drivetrain except from a Z28 and l am wondering how similar the output is between them.
my car did 314 HP at the rear wheels.
also have you weighed your car yet?
i got a certified weight and it was 2730 pounds with a full tank of gas and about 20 pounds in the trunk without me in the car.

 

Sounds like you are making good power. I would love to get my car on a chassis dyno and see where it is sitting in comparison. I will probably get around to doing that as well as weighing the car sometime this spring. I will give you an update once I have.

I reached out to V8 Roadsters and they responded with this: "The kit you link is for the LFX(V6) conversions. You could adapter the kit for use with the LSx and build your own lines from the water pump to the firewall. We provide -8 and -10 bulkhead fittings with the kit."

I am going to see if they will sell just the AN fittings that connect to the copper pipe as I am planning on building my own lines from the water pump to the firewall. If they can sell them separate, I think they will be worth buying to see if they will fit.

 

FYI, I called JEGS and worked thru the heater connection thing with a tech support person.
They do have a AN10 fitting that adapts to 5/8" OD tubing. It uses a crush brass seal ring just like the stuff you buy at the hardware store to connect to the 5/8" OD heater inlet and outlet copper tubing.
The JEGS part number is 555-110555
Once you get to the AN end you can use a 10AN 90 degree elbow where it presently goes thru the firewall.
You simply have to be really exact on where you cut the existing copper tubing in the firewall area.
I believe you can do all that and just need to pull the heater core without needing to remove any of the dash.
Then you will need to do whatever it takes to install AN fittings at the water pump connections.
I believe they have fittings that are AN to some Pipe Thread size that could potentially be tapped into the water pump housing.

The V8 Roadster kit for the LFX swap that moves the firewall connections from the driver's side to the passenger side simply uses rubber heater hose clamped onto the small pieces of copper tubing that connects to the heater core and runs the rubber tubing behind the air conditioning ductwork then converts to AN fittings where it goes thru the firewall. I sent an e-mail and requested they send me their installation instructions. The instructions were simply a series of pictures showing the routing and connections.
It would absolutely work for the LS swap but would have extra fittings that would not be needed.

I seem to be having a bit of problem with slight leakage where the tubing actually connects to the heater core.
The little clamp that Mazda utilizes to seal the tubing to heater core connection is really crappy looking but so far as I can tell there is no way to get away from it.
My current plan is to remove my seat and lay under the dash and see what I can do to seal up that connection.
When I first noticed that I have some antifreeze under my carpeting I was worried that my copper tubing was leaking but after putting a pressure test on the line, mine is definitely at that joint.
Hopefully some silicon high temperature form-a-gasket slathered onto the joint will make the problem go away.
If that doesn't work the only alternative I can figure is to braze or weld the tube directly to the heater core, something very tricky.