Miata LS3 Build Thread
They will be explosive off idle and in the mid range but will be down in hp up top.
The afr 215 head is a better match for a 6.2
You could go to a 235 head but it would be a bit flat down low till it was stroked.
if the OP has plans of doing a stroker engine 416 I would get the 235cc.
I’m in the short block about $1700 which includes forged rods/pistons. The goal was just to replace the tired LS1.
I dynoed the old LS1 last year. When I get this done and put some miles on it, I’ll dyno again and see how it compares.
I built the fixture out of wood, because I had wood on hand ...
Getting ready to drop the engine off the stand onto the fixture ...
Engine on fixture ...
I had some clearance issues around the oil plumbing on the drivers side ...
Passenger side no such issues ...
Sitting on fixture, ready for new clutch to go on ...
Clutch is on ...
All the wood wood reminded me of that. Too funny
The Best V8 Stories One Small Block at Time
I have two potential issues. The front sway bar may interfere with the ATI damper. That would be an easy fix ... move it forward half an inch or so. The hood may have a clearance issue with the new LSXr intake manifold. I hope I don't need sheet metal work on the hood to make it clear ... that would be expensive to maintain the stock look. I could hack it, but that's not what this car is about. Fingers crossed. :-)
It took almost a month to figure out the solution to the RPS BC2 Carbon Clutch install issues. Long story short, the slave cylinder I had was not able to collapse far enough to provide the necessary diaphragm finger to throwout bearing clearance. A stock 2009 Camaro slave was all that was required. I also shimmed it up .093", using aluminum shims I got from ebay (to save weight over the Tick steel shims). Some may laugh at my weight savings there, but this is a sports car. If you watch the ounces, the pounds take care of themselves. It weighs 2400# and will have close to 500 rwhp with this engine. I especially watch weight on the front axle, in order to keep the weight distribution suitable for nice handling in the corners. That was one of my major motivations for going to the RPS clutch assembly, which is 25# complete. The Mantic twin disc setup it replaced worked awesome (will be for sale, only ~5000 miles), but weighed 37# (stock Corvette parts I used to start were 52#). That's fine for a Camaro or 'Vette, but this is a Miata. Doesn't need that much flywheel/clutch weight.
The part of the harness that stays on the motor is now installed. I moved the knock sensor on the drivers side forward to get it away from the header. The wires were getting crispy in the stock location.
Accessories are back on, except for alternator, which lives on the lower right. I want to prime the engine with oil before I install it.
Last edited by grubinski; Jul 29, 2020 at 07:35 PM.
You can see the custom wiring I did to make it easier to install/remove the powertrain. A lot of stuff is easier to do with the engine out, because Miata == clearance issues.
You can see the plumbing for the remote filter / thermostat under the drivers side header. The steering shaft runs between the header tubes to the rack, which bolts on to the crossmember.
Tight clearances to both the starter and front subframe on the passenger side header.










