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Shuka

The LE5pard - Nix's Ecotec Miata Build

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I don't disagree with that-- OEMs have put millions of cars on the road without burning everyone, but that still doesn't mean I *like* the philosophy of a pressurized tank of steam in the engine bay!

 

Better leave the cap off your radiator then! I've had more plastic radiator tanks and rubber heater hoses rupture than expansion tank problems.

 

In any case - anyone have a good suggestion for sealing a radiator cap? I'm using the standard Miata radiator, but relocating it lower. I don't want any coolant to leak from that cap. I'll fill from the expansion tank, which will also have a standard radiator cap with pressure valve.

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Better leave the cap off your radiator then! I've had more plastic radiator tanks and rubber heater hoses rupture than expansion tank problems.

 

In any case - anyone have a good suggestion for sealing a radiator cap? I'm using the standard Miata radiator, but relocating it lower. I don't want any coolant to leak from that cap. I'll fill from the expansion tank, which will also have a standard radiator cap with pressure valve.

I know I know.. it's a mental thing..  but 230F steam is way meaner than 230F liquid if you just happen to be shot in the face with either.   

 

Look for Greddy 12400907.  It's the dummy cap that comes with their swirl tanks- intended exactly for this purpose.

http://www.greddy.com/products/ic-oil-rad/rad-breather/filter:model:most+Nis%2C+Sub%2C+Maz%2C+some+Toy%2C+Mit/

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Better leave the cap off your radiator then! I've had more plastic radiator tanks and rubber heater hoses rupture than expansion tank problems.

 

In any case - anyone have a good suggestion for sealing a radiator cap? I'm using the standard Miata radiator, but relocating it lower. I don't want any coolant to leak from that cap. I'll fill from the expansion tank, which will also have a standard radiator cap with pressure valve.

 

I actually bought all the parts to build a setup like this for my car, but haven't gotten around to it yet. I planned to just de-spring my current cap and use that nipple as a bleed off point for the system. Could you do the same?

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I actually bought all the parts to build a setup like this for my car, but haven't gotten around to it yet. I planned to just de-spring my current cap and use that nipple as a bleed off point for the system. Could you do the same?

 

That's not a bad idea! I don't trust the threads on that nipple to hold pressure, but I could sure as heck weld it closed.

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I know I know.. it's a mental thing..  but 230F steam is way meaner than 230F liquid

 

It's not a mental thing, it's a very real thing.  100C steam has almost 4x the energy of 100C water.

 

 

figure-15-03-03a.jpeg

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It's not a mental thing, it's a very real thing.  100C steam has almost 4x the energy of 100C water.

 

Yeah there's that (I'm well aware of that whole enthalpy thing with multiple years of ChemE under my belt)..   but the other side of that coin is that if a hose or radiator lets go on track, the leak is likely going to be spewing steam by the time you find out about it and get the car stopped..   so in any of those cases, everyone would be well advised to keep the hood closed and wait for the volcano to stop!

 

But in the case of the steam bomb, *if* you're dumb enough to pop that cap off while the system is hot and pressurized (or otherwise open the gate of hell), you're going to instantly paint yourself with 3rd degree pain.  if the car is at/near overheating and the fluid in the swirl pot is 230F, then the existing pressure will escape and drop the boiling point of everything in the system--- then the remaining fluid will flash boil and pretty much blow up in your face.  OMG bad situation.  again..  the main trick is to not be stupid enough to think you can take that cap off at ANY point the water temps are above about 180F..

 

the biggest difference between the expansion tank and a standard system is the tank provides a larger expansion chamber for the fluid to boil into steam during an uncontrolled release..   we all know opening a hot cooling system is bad, but these are moar bad.

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My solution is really simple.  I squeeze a radiator hose.  If it's firm, it's not safe to open the cap.  If the hose is squishy, it's safe to open the cap.

I don't think the surge tank is going to make a difference.  For the sake of discussion, let's assume that Shuka suddenly forgets everything she knows about thermodynamics, pressure, cooling systems, and common sense, and decides to open the cap while the engine is hot.  It's not going to happen, but we're being hypothetical.

The pressure loss is experienced through the entire cooling system simultaneously, causing bubbles of steam to form throughout the system.  It's just like shaking a hot soda and then opening it.

The key point is that the steam doesn't just form on the surface of the coolant.  It appears everywhere in the system, and this steam forces the remaining liquid coolant to move towards the only opening in the system, the just opened filler cap.

The result is a blast of foamy liquid coolant, being forced out of the system by the sudden presence of the steam bubbles.  This is going to happen even if there's no surge tank (as my dumb 16 year old self found out the hard way).  The presence of the surge tank isn't going to make a difference.

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we're picking nits at this point, but the difference is that opening a cap on a "wet" system will result in foamy mess of steam and liquid..  opening the top of an expansion tank gives the fluid a larger chamber to separate steam from hot liquid before exiting, so it will primarily be shooting steam at you, which as shown above holds more heat energy than liquid nasty.  in any case you'd be stupid to open a hot system, but the consequences of blowing the top off an expansion tank are slightly worse.

 

..... I'd bet there's an occupational safety study on these guys somewhere, but you'll probably have to have a paid subscription service to industry data in order to find it..

 

 

Shuka, sorry for the digression..  but you know how people like to argue on the interwebs. :)

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Have you managed to figure out why the OEM put that recess into the oil filter housing? Or did you replicate it with your weld repair? It seems awefully arbitrary to have that there. Suggests there may be reason for it...

 

Your TIG welding is looking good!!!

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Before replacing the pitted cams, I decided to do a leakdown check. #4 came up with a bad leak through the intake valves. Could be junk in the seat from its time in a junk yard, could be more sinister. So it was time to pull the head.

 

Similar to the K series and Miata, the Ecotec uses oil driven cam gears to adjust cam timing. The LE5 Ecotec has both variable exhaust and intake timing. I took this picture to make sure I would know what it's supposed to look like at TDC when I'm reassembling.

le5pard40.jpg

 

With the head pulled I took a look at the valves. Something is up with #4. It's possible the engine sat somewhere with these valves open, thus inviting moisture and corrosion in.

 

le5pard41.jpg

 

With the head at the shop, I'm stalled on cooling, exhaust, etc. But I have plenty of other prep to do for the coming season.

 

Installing the Mazda control arm mount gussets. My MIG was out of gas so I had to use the TIG. My carbon steel welding needs more practice!!!

 

le5pard42.jpg

 

STEAM BOMB! The coolant surge tank. The threads suck so I'm going to have to weld the AN fittings on.

 

le5pard43.jpg

 

Since ST5 rules penalize offset lower ball joints, I switched them back to stock. I picked up new front upper control arms and installed ISC racing offset bushings. The rear uppers will receive similar treatment.

le5pard39.jpg

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Looking good, are you going to lap the intake valves on #4?

 

I have the head at a machine shop now to go through the whole thing.

 

Have you managed to figure out why the OEM put that recess into the oil filter housing? Or did you replicate it with your weld repair? It seems awefully arbitrary to have that there. Suggests there may be reason for it...

 

Your TIG welding is looking good!!!

 

I found out that some models have an oil->water cooler that attaches to the housing and connects right there. WHOOPS. And thanks, my TIG is getting better but needs a lot of work. See above carbon steel welding on the subframe. I'm at the "functional but not pretty" stage of TIG welding. Haphazardly stacked dimes are just as strong as perfectly stacked dimes right? :)

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I thought you have to use an unmodified subframe.

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Gotcha, then clearancing for oil pan and header fittment and reenforcing should be legal?

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It's not critical yet, but still no word from AlphaFab on the harness/ECU. So while the head is at the shop, I did some steel work.

 

le5pard44.jpg

 

Better crash protection has been on the list forever. I had purchased a "bash bar" from Drift Armor, which I welded to the frame. I used some leftover steel tube from the truck bed project to build a lower beam as well.

 

le5pard45.jpg

 

It's super heavy duty, but that's OK with me. I'm not quite done here either. I'm going to add tubes between the bumper and the lower beam for even more added protection!

 

I also finished welding fittings on the coolant system. The steel tubes gave me more trouble than they should have, since the TIG didn't react well to whatever coating (probably galvanized) the manufacturer put on there. I caved and used the MIG to weld the crap out of the heater fittings. I put a coat of paint on it to protect the bare steel from corrosion. 

 

le5pard47.jpg

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Gotcha, then clearancing for oil pan and header fittment and reenforcing should be legal?

 

Nope, that is explicitly illegal. You can drill 3/4" holes, but can't 'channel' them together or do much more than that. Having fought this rule for the last two years, the explicit intent is to limit engine swaps and mods. They basically box you in by requiring unmodified transmission tunnel, floor pan, and subframe.

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Dumb . It really limits certain swaps . Make no sense . 

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Dumb . It really limits certain swaps . Make no sense . 

 

Yeah, it's why I went from K-swap to ecotec. I can make an easy 300 whp with either, but this one happens to have a front-mounted oil pump and forward pickup. I'm spending thousands of dollars to put a slower car together, just because modified/aftermarket subframe had me stuck in ST3. Otherwise I would have detuned or run a less powerful version of the K motor.

 

NASA told me that it was intentional - to limit swap options. 

 

An S2K or ND Miata have a lot more options because they don't really have much of a cross member. The NA/NB are severely limited and I think it's very much intentional. Really the message from NASA is "we don't like Miatas in ST5+. Pick a different car."

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Clearancing isn't allowed, but strengthening is.

I guess the theory is that a major weight reduction could be done in name of "Clearancing" if someone was feeling sneaky.

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Clearancing isn't allowed, but strengthening is.

I guess the theory is that a major weight reduction could be done in name of "Clearancing" if someone was feeling sneaky.

 

It's allowed, but only what you can get out of a 3/4" hole:

 

1a) Frame rails, sub-frames/suspension cross-members, and unibodies may have maximum diameter 0.75” (3/4 inch) holes drilled into them for purposes other than lightening, such as for the attachment of ancillary parts. Cutting and channeling is not permitted.

 

Waiting on the head, I built a quick bracket for the STEAM BOMB coolant reservoir.

 

le5pard54.jpg

 

le5pard53.jpg

I got the head back from the machine shop on Thursday, which meant a  weekend of big progress. I used ARP head studs this go around. You can see the guts of the Ecotec Miata swap kit in this picture. There's an aluminum adapter plate to match the Ecotec to the Miata's bell housing. I'd feel better if it were steel. I had to grind on one of the machined recesses for the mounting bolts, as it wasn't deep enough to allow the bolt head to sit flush. 

 

The stock flex plate is installed, then the Ecotec Miata adapter puck, then an OEM Miata flywheel.

 

le5pard51.jpg

 

The engine dropped right into place.

 

le5pard52.jpg

 

I replaced the timing chain set right after installing the engine. It's a pretty simple process. 

 

 

le5pard50.jpg

 

Priority one at this point was to figure out exhaust. I knew the fit would be tight through the OEM subframe, but until the transmission, slave cylinder, and PPF were in place I had no idea if 2.5" exhaust would work.

 

The header is for a Polaris Slingshot, which uses the GM LE5 as well. The only place for a pipe to go through is that little gap between subframe, slave cylinder, and tunnel:

 

le5pard59.jpg

 

The good news: A 2.5" pipe can get through. Bad news: at a weird angle and just barely.

 

le5pard58.jpg

 

With that, I got to work! I came up with a trick to fit pieces of pipe together for test fitting. I loosen the clamps just enough to allow adjustment, but not so much they slip out of place:

le5pard62.jpg

 

Carefully fitting, welding, testing, fitting, repeat:

 

le5pard61.jpg

 

Tackling the super thick flange:

 

le5pard60.jpg

 

Another test fit, making sure to install the gaskets and get everything tight:

 

le5pard57.jpg

 

And we have a downpipe!

 

le5pard56.jpg

 

I mulled over bringing the exhaust over to the driver's side (under the transmission) or through the PPF, or deleting the PPF entirely. I settled on routing the pipe along the PPF down the passenger side. Sunday's project was getting from the downpipe to the differential:

 

le5pard55.jpg

 

I'm getting halfway OK at TIG welding stainless!

 

le5pard63.jpg

Not a perfect, rainbow colored stack of dimes, but close enough for race car!

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@@Shuka, are you planning any supports for the header/manifold/downpipe structure? It looks like a lot of mass being supported at the head. I would be worried about the exhaust cracking somewhere with constant engine vibration.

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@@Shuka, are you planning any supports for the header/manifold/downpipe structure? It looks like a lot of mass being supported at the head. I would be worried about the exhaust cracking somewhere with constant engine vibration.

 

Supports are coming! It's a project in itself due to exhaust on the "wrong" side of the car.

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Supports are coming! It's a project in itself due to exhaust on the "wrong" side of the car.

 

So that's my problem!!!! My exhaust is on the "wrong" side as well!!!! LOL!!! j/k I know what you mean.

 

Your welds are looking great! I can tell you learned alot from the Kswap. Is this an easier swap in terms of aftermarket support with better parts engineering?

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