Jump to content
Shuka

The LE5pard - Nix's Ecotec Miata Build

Recommended Posts

What? You thought I was done?

 

I sold the K-swap setup as a complete package and pulled it out of the car. I wanted to run ST4 (or now even ST5) from the get-go, but the K-swap non-oem subframe and NASA's unwillingness to budge on an exception had banished me to ST3.

 

Using the proceeds from the sale, I set my sights on an entirely new kind of madness. A Chevy Ecotec!

 

Key long lead components are on order. AlphaFab promised 14 days on a wiring harness and ECU, so I went with them. I did this as the "easy button" and so I'm not relying on a bunch of hand soldered splices like my K-swap harness.

 

The car as it sits now. Everything pulled off:

 

le5pard1.jpg

 

A Houston local had a full Ecotec swap kit from Ecotecmiata.ca AND an engine for sale, so I jumped on it.

 

le5pard2.jpg

 

On the left: An LE5 Ecotec (2.4L from Cobalt SS NA car.)  On the right: A K24A2 mounted on subframe for transport to its new owner.

 

It's an interesting comparison. The K24 is a tiny bit longer and taller. What really make the difference is the oil pump and pickup location. The LE5's oil pump is above the crankshaft, and the pickup interface is on the very front of the block. The K24's pump hangs down into the pan (which would collide with the OEM subframe,) and the pickup is on the back of the pump.

 

le5pard3.jpg

 

K24 on its way to a new home. The truck crane is AWESOME for moving motors.

 

le5pard5.jpg

 

The LE5 swap kit components included cooling hoses, power steering, sway bar relocation, and a few other things I won't be using.

 

le5pard7.jpg

 

Kind of a weird motor, but simpler than the K24 in a few ways. It does have VVT on both intake and exhaust cams, but no more VTEC :( The Ecotec is similar to the K series motors, in that many of the parts are direct bolt-ons and swaps for other motors. This particular one is from the Cobalt SS, in the short time they produced the car without a turbo or supercharger. 10.4:1 compression, forged internals, 2.4 liter displacement. Factory rated at 171 hp.

 

le5pard8.jpg

 

 

le5pard9.jpg

When I picked up the motor, the seller had removed the valve cover (I have no idea why) and left it off. The exposure to the open air caused the cam lobes to pit. He agreed to give me a lower price since I would need to replace them. 

 

le5pard4.jpg\

 

Time to get to work! Prepping for the new oil pan. The sort of rectangular port at the rear left of the picture is the oil pump suction. It interfaces to the pickup in the pan through a liquid gasket seal.

 

le5pard10.jpg

 

I had to file a bit of the casting flat. I also touched up the oil pan a little, grinding down a raised weld on one of the mounting bolt holes, and adding weld on the sides of the baffle hinges since I was told they fail (the weld along the top of the hinge breaks.)

 

le5pard11.jpg

 

I used a BUNCH of RTV to put this together, but it reminded me of the Kmiata oil pan. I think a do-over may be in the future with some ultra-flange to get a proper seal.

 

I was a little surprised to see how it all goes together. The sump is out in front of the engine, past the steering rack!

le5pard6.jpg

 

The upside is that I have the swap kit in-hand, so progress should go very quickly!

Share this post


Link to post

So does this mean you're gonna shaddup now about the WRL car

 

It could go either way. I might be doubly enthusiastic!

Share this post


Link to post

Very strange sump arrangement.  is there any concern of oil starvation or backup into the bottom of the block due to cornering forces and the shallow section of the pan not being able to drain to the sump quickly?  

strange....

Share this post


Link to post

Very strange sump arrangement.  is there any concern of oil starvation or backup into the bottom of the block due to cornering forces and the shallow section of the pan not being able to drain to the sump quickly?  

strange....

 

Yes concern, but I'm using the 2 qt accusump too so that should help. There's baffling in the pan too, but people have lunched motors due to oiling issues with this setup.

Share this post


Link to post

Yes concern, but I'm using the 2 qt accusump too so that should help. There's baffling in the pan too, but people have lunched motors due to oiling issues with this setup.

I'm less concerned about the baffling than I am about the ability of the engine to evacuate oil from below the engine and into the sump while under acceleration and cornering.  I'm sure you've probably thought about this to some extent, but what about dry sumping?   it would require a slightly different pan, but you could put a scavenge stage front and rear and still keep the shallow pan. ???

 

yeah, more effort and a fair amount of extra cost.

Share this post


Link to post

Do you need to de-tune it for ST5, or crap load of ballast? I remember your car being very light.

 

This will be a focus toward the end of this build.

 

For ST5, a car has to weigh 2400 lbs to use 225 tires. So that's the target... my declared race weight at Hallett was 2100.

Share this post


Link to post

That was with 75 lbs of ballast, cool shirt, passenger seat.

 

Dry and stripped without driver it was 1880 lbs.

 

I'll be adding some accessories, mounts, bars, safety gear, a big battery, and the max allowed 250 lbs of ballast to hit ST5 2400 lb comp weight.

Share this post


Link to post

Weight gain is on the backburner for now. My primary goal is to get the engine in and running!

 

Our delivery drivers must LOVE us...

 

le5pard23.jpg

 

Despite the package mountain, it was just a few parts, one of which was a brand new subframe from Mazda!

 

 

le5pard12.jpg

 

Removed the water manifold thingie from the engine. I'm still working out how I want to plumb it all.

 

le5pard18.jpg

 

The LE5's water pump suction port

 

le5pard15.jpg

 

Working on motor mounts, I had to run a tap through the threaded but virgin holes in the casting.

 

le5pard16.jpg

 

And off the stand for a test fit! The Ecotecmiata oil pan is strange, but apparently the forward sump is what they ended up with after several iterations.

 

le5pard13.jpg

 

Getting the motor mounts bolted to the crossmember was a little tough. The NB steering rack is a tight fit. I'm told many convert to manual rack just for clearance, but I'm going to try modifying this one first. I also don't like the tiny bushings used for the actual mounts. I'm pretty tempted to get some Hasport urethane mounts and build my own motor mounts!

 

le5pard17.jpg

 

The squared off part of the oil filter housing will get a trim to better clear the body.

 

le5pard21.jpg

 

And there's a major annoyance that could have been fixed with more elaborate fabrication. Zero room between the crank pulley and oil pan, which means to change the accessory belt the crank pulley has to come off! I also worry about rocks getting in the "mill" and tearing up the belt.

 

le5pard22.jpg

Share this post


Link to post

Pics are dead links?

 

I changed my hosting... could be some issues there.

Share this post


Link to post

I changed my hosting... could be some issues there.

 

please fix, I need pics :) 

Share this post


Link to post

gosh that oil pan is terrible. looking forward to following the build tough!

Share this post


Link to post

gosh that oil pan is terrible. looking forward to following the build tough!

 

It's really not too far off from the OEM pan, just moves the sump forward like 6 inches. I'm definitely augmenting it with an accusump!

 

I'm still waiting for a few key parts (mainly the new Ecotec auto transmission flex plate - the junkyard one attached to the motor was bent) so I'm doing what I can. I pulled the steering rack and repacked it, and welded the pinion shaft as well since I didn't do it when I originally de-powered the rack. I used Fred's suggestion of wet paper towels around the shaft to prevent the weld heat from getting to the bearing and the rest of the shaft while I TIG welded. I had already started to repack the bearing when I took the picture (I didn't weld with grease like that!)

 

 

le5pard37.jpg

 

I also notched the transmission for fitment to the Ecotec starter (bottom.) There is already a similar notch for the K series starter.

 

le5pard27.jpg

A made a cover for the K-starter hole, but didn't grab a picture.

 

 

While shaving things to make better clearance for the engine, I went after the outcropping on the oil filter housing, which was at risk of rubbing on the side of the engine bay.

 

le5pard36.jpg

 

As I completed the cut, I noticed a little hole. OH NO! 

 

le5pard33.jpg

 

For whatever reason there's an indentation there and I didn't bother looking inside before I started cutting. Not the end of the world, but the easiest fix seemed to be to TIG a little plate over it. Since I was welding on the block anyway, I also installed -16AN fittings on the water outlet and inlet. 

 

Filter housing hole fixed, and water outlet AN fitting welded...

le5pard26.jpg

 

I gave the thermostat housing the same treatment.

 

le5pard35.jpg

 

I'll be adding a -10AN fitting on the bypass port for the surge tank as well. It's not the prettiest welding, but it's functional!

 

le5pard32.jpg

 

Giving more thought to the cooling system, I also wanted to add a port for my temperature gauge where it would get the best reading of the engine temp, so I tapped a 1/8 NPT hole right into the bypass / heater outlet.

 

le5pard34.jpg

 

Also on the cooling system, there's a high point port on the water outlet (GM calls it a steam hose) but I want to plumb this to my surge tank as well. I tapped the originally M8 port to 1/8 NPT to accept a standard AN adapter fitting. (blue plug in the picture.)

 

le5pard28.jpg

 

I spray painted the crusty valve cover, test fit the header, and did a few other odds and ends, but overall a relaxing weekend with small bits of progress.

 

le5pard24.jpg

 

le5pard25.jpg

Share this post


Link to post

Aside from patching holes in the block casting, I spent a good chunk of time mocking things up for the cooling system, and ordering hoses and fittings. With the K24 build, I essentially re-engineered the OEM cooling system, but I learned my lesson. I wanted to emulate the donor car's original cooling system as closely as possible, so I went with a pressurized surge tank design. Here's a diagram of what I'm building:

 

le5pard38.jpg

 

The surge tank will be higher than the rest of the engine, and the "steam hose" will push air bubbles here from the engine. It's essentially a self-purging cooling system. This mimics the factory design, since, like the donor car, my radiator is lower than the head. Also note I added a heater core and H valve. I'll add this later; for now I'll just loop the lines. However, I do plan to add the heater core for the cabin, mainly for window defogging.

Share this post


Link to post

I like that steam hose concept.  wish Nissan would have done that with their VQ engines as they are notoriously hard to purge (the 350Z and Maxima FSMs show use of a vacuum attachment to the radiator cap and jacking the front of the car several feet in the air.)

 

I don't like the pressurized tank from a safety standpoint (steam bomb!), but as long as nobody is dumb enough to open it while hot, everyone should keep their skin intact.  I guess you can't really have the steam hose/ self-purge without an air gap/ swirl tank in the system somewhere though, so it's a necessary evil for the self-purge.

Share this post


Link to post

I like that steam hose concept.  wish Nissan would have done that with their VQ engines as they are notoriously hard to purge (the 350Z and Maxima FSMs show use of a vacuum attachment to the radiator cap and jacking the front of the car several feet in the air.)

 

I don't like the pressurized tank from a safety standpoint (steam bomb!), but as long as nobody is dumb enough to open it while hot, everyone should keep their skin intact.  I guess you can't really have the steam hose/ self-purge without an air gap/ swirl tank in the system somewhere though, so it's a necessary evil for the self-purge.

 

Considering the "steam bomb" design is used in many, many modern cars, I don't think this is a stretch. And most production cars use plastic tanks, not aluminum. It will still have a relief cap at 15-19 PSI.

 

So how long before you're mass producing these fixes for EcotecMiata?

 

So far the kit itself seems pretty well done, really. I don't like the tiny bushings in the motor mounts, but they're good enough for now until I build beefier ones.

Share this post


Link to post

Considering the "steam bomb" design is used in many, many modern cars, I don't think this is a stretch. And most production cars use plastic tanks, not aluminum. It will still have a relief cap at 15-19 PSI.

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!

Share this post


Link to post

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×
×
  • Create New...