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Mazda Engine Swap

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Bill Blue

Platinum Level Sponsor
It is going to be a chore to keep all of the header and collector above the steering arm. Vertically, it is pretty tight. Horizontally, it is pretty tight. Should be a lot o'fun! I had to run the exhaust in front of the arm, and tight to the block in order to avoid the upper fulcrum. I am running a 2" pipe, there just is not much room for a single, large pipe.

I do think that perhaps a person could extend 1 5/8" primaries between the block and steering arm with the collector running horizontal under the car. That would be good, allowing the primary length to be tuned. I could not do that as the exhaust has to cross under the engine. Did not want to deal with that mess.

Bill
 
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V6 JOSE

Donation Time
Hi Bill,

This is just a suggestion, but why not put the exhaust pipe out through the fenderwell? My turbo Alpine had it like that. There is lots of room between the inner fenderwell and the wheel. The turbo Alpine had a 4" pipe behind the wheel, and the onbly time the tire touched the pipe, was at extreem left turns, like those made in a parking lot. It has run like that since 1983, when it was first put together. You can miss all the steering arms and stuff and it is simple to connect up to go through the stock exhaust pass through in the cruciform.

Jose
 
B

Bill Blue

Platinum Level Sponsor
Jose, I think that is an option for Robert as his exhaust is on the left side. The Duratec exhaust is on the right side which opens another can of worms.

Bill
 
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V6 JOSE

Donation Time
OK. I didn´t know that your exhaust was on the right side. At least you don´t have to work around the steering box.

Jose


Bill Blue said:
Jose, I think that is an option for Robert as his exhaust is on the left side. The Duratec exhaust is on the right side which opens another can of worms.

Bill
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robertf

Donation Time
drove to Dallas over the weekend pretty much just to measure the car :D I think I got it. The tube lengths aren't balanced, but they are much closer than the factory mazda header which had a min/max difference over 4" !



the flange came in and it is really nice. Time to order tubing.


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B

Bill Blue

Platinum Level Sponsor
Robert, I have read that differences in the primary tube length are important only if you are trying to maximize power in a narrow power band. The area under the power curve remains the same. However, chances are your primaries are going to be too short to see any tuning benefits at the rpm's you will be running.

Me, I'm just glad I was able to gather all the exhaust at one point without resorting to a log manifold.

Bill
 
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robertf

Donation Time
I hear ya

I messed with the numbers some more and got everything to 10.715 +/- .005

tube is in the mail, and I've got access to a tig this weekend so I'm hoping I get some stuff done.
 

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robertf

Donation Time
the bandsaw is not +/- .005, so I'm sure there will be some cheater bars and weight thrown around.

1.375 16g 2.5 centerline radius mandrel bent.


I found a place that sells 2.25 CLR, could have shrunken the volume it occupies if I designed with that in mind. Maybe alpine #2 will get a revised manifold if this doesn't work and if I can't find a decent 1725 by the time I get around to working on that one.
 
B

Bill Blue

Platinum Level Sponsor
Damn! I wish I could watch, knowing how much trouble I had doing this simple thing made up. Would like to see how you do it. I'm pretty sure I couldn't, just don't have the ability to see how things fit together in 3D.

Bill
 
B

Bill Blue

Platinum Level Sponsor
OKAY!!!!

I'd never be able to squeeze that in between the engine and steering arm. The Duratec must be a lot wider than the Mazda. Could there be that difference between left and right sides? But then again, as they say, "It's an Alpine, your results may differ".

Bill
 
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robertf

Donation Time
Bill Blue said:
OKAY!!!!

I'd never be able to squeeze that in between the engine and steering arm. The Duratec must be a lot wider than the Mazda. Could there be that difference between left and right sides? But then again, as they say, "It's an Alpine, your results may differ".

Bill
Click to expand...

The pulley lines up with the crank start hole in the grill, and the transmission is centered in the tunnel so there shouldn't be any difference left and right.
 
B

Bill Blue

Platinum Level Sponsor
My engine is centered, have 1.9" between the engine and right steering arm when turned to full right lock.

Bill
 
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V6 JOSE

Donation Time
Robert,

That is a nice looking installation. I love the headers too. I wonder how it will run when it´s done. Should be a nice little runner.

Jose
 
R

robertf

Donation Time
Thanks Jose, I'm hoping the 25 year technology advantage outweighs the missing 125cc's.



The hard parts that are left from easiest to hardest are

intake ductwork
cooling system
transmission shifter

I've got 4" between the radiator and throttle body and it needs to take a 90* to get out of the way then route through the opening where the horn goes. I've found a silicon elbow with a 2.5" radius. The smallest radius I can find in metal is 4" I'm hoping the silicon does the trick, if not its going to be ugly.

The cooling looked hard at first, but I've found that the miata cooling is an after thought since these were originally transverse mounted. Lots of miata folk reroute it that way and put the thermostat in the back of the head where its got a heater outlet. The current thermostat ends up being a heater line. This is supposed to cure many overheating problems that show up at the track. Routing it this way would let me use an unmodified radiator. Keeping it stock would require swapping the inlets and outlets, and then theres the possibility that the radiator is undersized for this app.

The transmission shifter is a nightmare I'm not going to think about until I have to. I'm probably not going to cast stuff like I originally planned, just a remote shifter like Bill discussed in the other thread. Going to have to pull the transmission probably a dozen more times to measure, cut, fit. The car has been moved out of the garage and off jack stands so it'll probably be a full day of playing real world tetris just to get it back in place to work on.

Theres also wiring, but I've lost track of how many EFI swaps and conversions I've done so as long as the megasquirt doesn't let me down this shouldn't be a problem. I haven't looked at the gas tanks yet. I understand there are 2 and a balancer tube. I'm guessing the stock fuel line ties into the tube, so that might be replaced and ran to the pump. I'll need to add a return line and might get lazy and just tie it to the fuel filler neck.

And I need to find a miata driveshaft and do some yoke juggling to get a half mazda half sunbeam shaft
 
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V6 JOSE

Donation Time
Hi Robert,

Your Mazda will blow the doors off of the stock engine. The Mazda is a newer design and these newer engines are so much more efficient, that there should be no comparison.

Jose
 
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robertf

Donation Time
I think I got the shifter figured out. Once I get some measurements this weekend I might actually send this to a fab shop and not get my hands dirty on this one.
 

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robertf

Donation Time
yes, using the stock holes and the stock shifter modified to bolt to the front holes instead of the back.

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