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nigelt gets bored and adds displacement (ecotec 2.4 turbo build)
This thread will document my swap to an ecotec (LE5) turbo, which takes the engine from a Chevy Cobalt SS (and HHR, G6 and others), combines it with the turbo gear from the 2.0 Pontiac Solstice GXP, and bolts it up to the Miata transmission. This is not a new car for me, but in the interest of more succinctly sharing knowledge of this swap with the community here, I'm branching this off from my current build thread.
A bit of background. I bought a totalled 2002 SE back in 2014 with the idea that I'd just bend it back into shape, shoot some paint on it, and slap on a turbo. At that point I had done a few autox events, but had never considered track days. Here we are almost 4 years later and from the terrible influence of this forum, it's now got a well sorted out MK Turbo kit, Xida GS suspension, aluminum seats, LS coils and a handful of other goodies. Along the way I put together a GT500 injector kit for myself, and in finding that other people wanted them too, I started Flow Force Injectors. My engine now needs a valve job, and I'm ready for a boost in reliability and power. Which brings us up to the present.
I was originally planning on doing a built engine, and bought most of the parts for it, and then changed my mind. I just couldn't wrap my head around the idea that if one thing goes wrong I could blow a $5k engine. Inspired by Ryan's LFX build, I started looking at alternative options. The LFX really appealed to me, but the costs on that swap really do add up, and there's a fair bit of modification required. The K24 swap gets pricey too, and I would take low down torque over wailing high revs for street driving. That led me to the ecotec swap.
My goals for the build:
300whp/300wtq with a wide torque curve
Disposable junk yard engine
Reasonable price point
Fab work is within the scope of my abilities
Possible test bed for my new Flow Force 960cc injector kit
And the LE5 fit the bill. The early years of this engine (2006-2007) came with forged rods and are supposedly good for 400whp+ in stock form when boosted. Also all the turbo running gear from the 2.0L LNF bolts right up, meaning OEM reliability and junk yard prices even for the turbo kit. Lastly, there's a good transmission option from the 5 speed Pontiac Solstice which should hold 500whp if I blow my 6-speed.
Engine
I was shopping for an eBay or junk yard LE5 from 2006-2007. They tend to go for $600-$1000, although I've seen reports of people finding low mileage power plants for around the $500 mark. Then I found a fully rebuilt LE5 with the stock forged rods from Alpha Fab for $1400 including shipping. I went for it to save myself the time and effort of doing jobs like the timing chain, head gasket etc. The downside, other than a slightly higher cost, is that it came as a bare long block. I had to spend a few hundred more tracking down things like the intake manifold, COPs, hardware, etc. If I did this again I'd probably spend the $1000 or so to get a really low mileage engine with the wiring harness and all accessories, and toss it in the car without worrying about the maintenance items.
Turbo
The turbo on the 2.0L turbo version of this engine is a fast spooling Borg Warner K04, and it bolts right up to the 2.4. You can get a brand new manifold, turbo, and oil and water lines for about $800. I found one of these that had been bought for a miata swap and upgraded to the "big wheel" version, which has a bigger compressor wheel for better high-end power for a couple hundred extra. It's quite surprising how easily it bolts up. I only had to drill the block for the oil drain, and pick up a couple other parts from the 2.0L to make it all fit.
Swap Kit
I went with the ecotecmiata.ca DIY racer swap kit, which tips the scales at $950. It uses the stock subframe, and just requires drilling the miata flywheel to bolt up to the LE5. I ordered it about 6 weeks ago, and I'm to understand it will be shipping out shortly.
ECU
Most people who run NA ecotec swaps, and even some turbos, use the GM ECU. It's reprogrammable, very capable, and reportedly well known by tuners. However it isn't as easy to tune yourself as megasquirt, and a license for the tuning software (HP Tuners) is a whopping $500. I'm going with Megasquirt, and picked up a built MS3x and 8 foot wiring loom from diyautotune. I'll build my own harness from that with the connectors I pull from a cheap cut LE5 harness I got off eBay.
Injectors
For the initial swap I'm probably going to fit a set of Flow Force 640 injectors. That will let me test out my work horse product in a new engine and hopefully open up a new market. Then I'll drop in my new 960cc kit, which will provide the fueling I need to put down the big numbers, and let me battle test that new product. For both the 640 and 960, it's not a direct fit with the Miata kit, but it's close enough that I can make it work with a few tweaks.
Intercooler
I'm going to keep the eBay intercooler I have now, and keep the 2.25 inch piping on the hot side. On the cold side I'm going to go up to 2.5 inch. I think I can keep the same piping routing, even though the intake and exhaust sides are switched.
Down pipe and Exhaust
I think this is going to be the hardest part. On the ecotec motors the exhaust is on the other side, and routing with the stock subframe is tough. My plan is the go 3 inches straight off the turbo and sneak it down the space available. I'll probably have to do some cutting and pounding to open up enough space. Then I'll cross over under the transmission and join up to my current MK Turbo exhaust. My plan is to cut and tack weld the down pipe myself, and then take it to a shop for tig welding.
At present, I'm collecting parts and assembling the engine. Within the next month I'll pull my engine, rip out PS and AC, and get it cleaned up and ready. Then at the end of April I'm planning to drop in the LE5 with plenty of time to fine tune and work out the kings before a weekend at Laguna Seca in June.
Excellent. I plan to return to MMRLS (or whatever they end up calling it) in 2019. I may be out in the south these days, but California will always be "home".
Do yourself a favor and buy a V8R front subframe. Makes exhaust routing SO MUCH EASIER. Really helped our build in December, since they had a black Friday deal, and I think we got ours for around $600. Doesn't hurt to ask if and when they'll go on sale again.
I usually suggest moving the right motor mount as well, but since your exhaust is pointing straight back from the rearish of the engine, instead of straight down from the middle like N/A cars, it's probably easier to just route it by the slave cylinder and heat shield the crap out of it. Run your down pipe first, then decide if a banjo, 90*, or 45* fitting on the slave will work best, I believe it's currently going to stick right into the are you're planning on routing the exhaust.
Please post how you handle exhaust! My major concern about this swap is the difficulty of routing a suitable exhaust system without having to literally move everything around (fuel lines, slave, etc.). I think this swap could still be cost effective even with the cost of a new subframe but it definitely increases complexity...
Please post how you handle exhaust! My major concern about this swap is the difficulty of routing a suitable exhaust system without having to literally move everything around (fuel lines, slave, etc.). I think this swap could still be cost effective even with the cost of a new subframe but it definitely increases complexity...
My current plan is to keep the stock subframe and go down and back on the passenger side and cross over under the transmission. I'm making extra space by replacing the clutch line with a stainless flexible line with 90 degree banjos. I'm learning to TIG weld to do the exhaust myself, and am hoping to learn some things that will help other folks going this route. I agree with you - the exhaust is my biggest concern at the moment.
I'm almost done prepping the engine for the install, which will kick off this weekend. I also returned my ms3x for a ms3pro evo and am having the leads made up into a harness to save me some trouble.
I also decided that I'll need to do my down pipe and exhaust myself so I got some welding gear and taught myself to tig weld. I built a welding cart to practice my as yet not quite mad skillz.
I also decided that I'll need to do my down pipe and exhaust myself so I got some welding gear and taught myself to tig weld. I built a welding cart to practice my as yet not quite mad skillz.
03-10-2018, 03:16 AM
nigelt gets bored and adds displacement (ecotec 2.4 turbo build)
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