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Cams going in now. We'll tune with all the bolt-ons and dyno before we add the blower. We chose the BC0401 (stage 2) cams. With prior experience on cams and Rotrex's we knew lift was more important than duration. The Rotrex makes plenty of power up top so the idea is to improve midrange by keeping duration as short as possible. Otherwise stock long block, cams, hooker header, GWR 2.5" catted exhaust, E85 kit and a DIY intake.
Cams going in this week and we ended up with a problem on the head. So we're going to source a shiny new big valve, CNC ported head from Esslinger. Oh darn.
New NC2 long block going in. BC stage 1 cams installed. Then corn and whooshy.
Not an Esslinger motor. They had some issues with communication (none) so I skipped that option and just ordered a new longblock form Mazda.
Keegan dropped the cams in for us, he know his way around the MZR having worked at Cosworth back in the day.
I know you said upthread you liked revs and that was why you didn't go for the 2.5, is there anything else about the 2.5 that would turn you off putting a Rotrex on one?
I know you said upthread you liked revs and that was why you didn't go for the 2.5, is there anything else about the 2.5 that would turn you off putting a Rotrex on one?
My opinion, 2.5 is a good idea if you do all the work yourself, are doing cams and forged internals and are happy with the 210whp or so they'll make on e85. Displacement always wins but the extra vibration, lower rev limit and far weaker bottom end are a negative for me. 2.5 also easy to sneak past emissions if you have such requirement in your state. Not sure what its like in Australia. We wanted 275-325whp so we would have needed a blower of some sort anyway. Easier to just bolt in the Rotrex kit. That and I like the powerband, having done a few Rotrex powered Miatas in the past.
So in our case, the 2.5 was pointless. We reached our power goal, it will run smoother and rev higher. Personal preference I guess.
Xero limit oil cooler. BBR stage 2 Rotrex kit, C30-94. Dyno tomorrow. Church Auto, Dynapack. Known to be optimistic, but I'll post anyway. Just take those numbers with a grain of salt.
The Zeitronix flexfuel set up isn't working. Soon as we connect it the canbus goes haywire. So we'll tune on the substance that passes for super unleaded here in Cali. On paper at least, it should make about 310whp on a Dynojet, maybe 330whp on E85. But we'll be happy with 270. With the stock engine, it was way overtired, over aero'd. Barely faster that a stock NC on good OEM sized tires.
It it was a race car, we would have spent more time getting the OFRK up near the firewall. To save time, we just mounted it off the front bumper support. Shorter lines, easier to get all the air out of the system.
Starting with some 0w40 Amsoil we had laying around. Hooker header, Magnaflow 2.5" catted midpipe, GWR street single, CAI, Crower stage 1 cams and valve springs, new NC2 crate motor from Mazda.
Michelin PCS2 240's on 18x10 GTC02's.
Well that was short. First pull on dyno. Motor let go at 7k. Log showed -4 knock retard, ecu pulled back, fed back in then boom.
So no Miata Reunion for it. Boo.
Ouch! That was 'a brand new crate motor'?! Any idea at this time of what let go (first), why?
Not yet. Either the motor needed more break in or it knocked and the ECU's native knock control didn't catch it. We'll know in a few weeks once it's torn down.
Not yet. Either the motor needed more break in or it knocked and the ECU's native knock control didn't catch it. We'll know in a few weeks once it's torn down.
My money is on assembly error of some kind, likely with the mechanical timing. Those things don't just blow on the first pull, even with boost.
Can 87.5mm pistons for the 2.3 be used in the 2.0? Would like to use Wisecos and they only list a "2.3" piston.
Supertech forged H beams as that's all I can find in stock.
Block has a hole on both sides. Looks like #3 rod snapped. Big end still on crank, part of piston pin and mangled piston visible. Makes me wonder if I ordered an NC1 long block by mistake..
Sorry to see this. I find it hard to believe that even the weakest nc motor would fail that spectacularly on the first pull. Casting defect on the rod?
Can 87.5mm pistons for the 2.3 be used in the 2.0? Would like to use Wisecos and they only list a "2.3" piston.
Supertech forged H beams as that's all I can find in stock.
Block has a hole on both sides. Looks like #3 rod snapped. Big end still on crank, part of piston pin and mangled piston visible. Makes me wonder if I ordered an NC1 long block by mistake..
I would not want to use 2618 alloy when much better options are out there like 4032 forgings (less thermal expansion, among other benefits). I believe the compression height is different between the 2.3 and 2.0 engines, so you would want to test fit one and see where the piston ends up vs the deck at TDC. K1 makes rods for the N/A 2.0, and I think Massive Speed stocks them. They stock Supertech 4032 pistons too. I'd just buy it all from them.
IMO, losing a rod catastrophically like that with a new long block points to an over rev, assembly or oiling mistake. I'd be very interested to see what the #3 rod bearing looks like. How many miles were on this engine before it was lost?
02-04-2023, 12:12 PM
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