Ok, so here’s my current setup - 95 1.8L “built” motor. However the guy I bought it from didn’t have receipts so you know how that goes. Claimed it had forged pistons and rods. Rotrex c3074 w/95mm pulley (Kraftwerks gen 2 intercooled kit). Mspnp2 dyno tuned 177/145 on a mustang dyno. For the past 2 years I’ve been gathering parts: -84 housing upgrade, 72mm pulley, 640cc injectors, new intake. All with the intent of trying to get to 230/190 ish power levels. My car is track only.
Ecotec Miata has resurfaced and seems like I could perform this swap and do a small turbo to comfortably get to 230-250/230-250 numbers, from what I understand pretty reliably.

I know this crew doesn’t care for the Ecotec engine, but I’m not looking at naturally aspirated ecotec trying to make 170-200hp. I’m looking for 250, reliable track hp, that won’t be overheating. I know I just hit a hot topic - I have a 3 row aluminum radiator, coolant reroute, ducting, and hood vents. My temps on track are about 210-215 in 20 minute session.

I like how my Rotrex drives, but it doesn’t have enough power. My former track car was a 487whp z06. I’m not needing that level of power. Just want more than what I’ve got now. And want to focus on reliability & longevity.

thoughts?

 

If you are only chasing 230/190 then you are only a pulley change (and maybe injectors which you already have sourced) from getting that.
pretty sure 949 made 300hp on their c30-74 so whilst not an apples to apples comparison, shows you don’t necessarily need to change much to get to your goal.

fwiw, my 240hp Rotrex’d NB1 runs all day long on track with no overheating, no issues with underbody heat, studs backing out, cracking manifolds, overboosting, having to drill sumps, or any of the other issues turbos sometimes create. I know most of these are solvable with time/effort/money but a rotrex for a track car is imo the easy option. Pretty much it’s bolt on, tune and go.

if you genuinely want to do an engine swap and the hassles that comes with that then go right ahead, but for your stated goals you are 99% of the way there with your current setup. An hours work and a retune and you’re done.

 

230whp on what you've got should be a breeze. Add injectors, a decent sized oil cooler, and proper ducting and go to town.

 

Ideally I’d like to be in the 300s, but I recognize the reliability falls off tremendously when you cross the 250 marker.

rascal- yes I’ve been accumulating parts to make that 230 marker.

if I were to do ecotec swap I’d be chasing 250-300. I hadn’t thought of using a solstice trans and a ppf brace to get to that 300 marker with a custom driveshaft. But that would avoid having to do a v8r rear end conversion that I don’t want to undertake…

 

I for one am a HUGE ecotec fan. My friends and I enduro raced one, then we turbocharged it and ran with the Trans Am cars. They're quite robust, and I'd own one 9 times out of 10 over a K-swap. Now parts, communications, quality control, and a few other factors made it difficult to recommend them over the last few years, but under new ownership, they seem to be turning around. Things like a billet flywheel in 1.8 size instead of 1.6 goes a long way to making it a better swap. Anyone looking to avoid turbo BP, high $$$ N/A BPs, or the Vibra24 should consider the Ecotec.

You may change your HP/Tq goals though. Since they're 2.4 liters, you're making bucket loads of torque, 300+, with only 250-260hp. You can get away from this with ramping boost in like a Rotrex, but that's probably not want you want. If you try to use a smaller turbo, it'll spool faster and make big torque. If you use a larger turbo, it'll still spool quickly and make buckets of torque. Haven't played around with enough turbo builds on them to tell you what the sweep spot is, but priority needs to be good boost control, because you're not going to be running much if you only want 230-250.

 

The new owner actually recommended the 2.0L motor that came factory forged rods and pistons.

glad to hear everyone isn’t against it. Seems like reasonable money for a lot of potential. The new owner also redesigned the oil pan. I’m basically at the point of no return on my setup. So if I’m questioning if it’s the right path.

my car is a track only car, is the rear end still an IED at 300whp if you aren’t launching it?

 

We don't usually see 1.8 diffs failing at 300whp. Mine was fine at 325whp on track.

 

Our build in Deviate was a 95R with a BP6D engine. 10.0:1 compression, CNC ported big valve head, Tomei cams, C30-74 KW prototype Rotrex kit, MS PNP2. No flexfuel but made 300whp SAE corrected Dynojet at around 9.5psi on E80. RB header, catted midpipe exhaust.
IIRC, I ran about 23° timing on top. Solid, reliable build with excellent street manners. Had great midrange torque, 240lbs @ 5500 IIRC. On pump gas and a plain BP05 head, I'd expect more like 240whp and a bunch less torque. 1.8 diffs are strong if not totally worn out before adding boost.
Most of the other common failure points in a low boost NA/NB are well documented here.
Your Z06 would have been around 6.9 lbs/hp. For your NA8 to math that would require about 370whp. Having driven a few 350-400whp NA/NB's, they're a handful.

 

Emilio thanks for chiming in. I’m the NE and they have all but taken away access to E85. I know 1 e85 station within 2 hours of my house. I’d be happy to run it but I’m not paying $11/gal while instructing.

my car weighs 1950 with 1/2 tank so it’s pretty light. I need to copy your cage design to make my car a little more aerodynamic but that’s another story…

you’ve all convinced me I’m going down the right path, now I just need someone to sell me a set of xidas for under $1500….