| MIATA BUILD |
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 | |  | September 11, 2013 - Want to know what the difference between the standard 430 hp LS3 and the 525 hp version is?
You're looking at it. That's an ASA cam from GM Performance Parts along with the appropriate valve springs. We have a car at Flyin' Miata right now with this cam, and it's ridiculously fun. Not just the obvious power, but the throttle response. It's one rorty engine, entertaining in a way that the other versions aren't.
So, while my new engine is out of the car, dropping these parts in was a bit of a no-brainer.
entry 1094 - tags: power, engine, ps3 | | |  | September 11, 2013 - The latest mad scientist project on the car: active aero.
I've been reading far too many Can-Am books. The rear wing is flipped up under braking by a pair of Miata headlight motors. It's triggered by the brake lights and takes 0.6 seconds to change position.
I'd originally planned to make this work with an expensive Spal linear actuator with a clever three-position controller that gave me a low drag position as well as the air brake, but it was far too slow - 0.5"/sec. The Miata motors are six times faster. I mounted them where I did mostly for simplicity, I didn't want to make any permanent changes to the car for these tests. They're not in an ideal place from an airflow perspective.
It's been suggested that I add a timer circuit to delay the return once I get off the brakes, and I might give that a try. This is just the proof of concept. I've got a track day this weekend, I'm going to bring this with me to see if it works.
Video!
entry 1095 - tags: aero | | |  | September 16, 2013 - Track time!
I was back at High Plains Raceway. I've come to enjoy this track more than I did initially, it's actually pretty fun. The best corner is a long uphill sweeper that has a fairly quick entry. If you do it right, you can keep full throttle most of the way through as you climb to a blind exit with nothing but sky to see.
The car went pretty well. It took me a couple of sessions to work out some little bugs and dial in the handling for the track, then it all came together. I spent some time playing with two CMC-class cars, Camaro/Firebirds with V8 engines. For the first session, I was about the same speed. Then I got faster and started hunting down the Viper that was sharing the track with us. Overall, a pretty good day at the track.
For fun, I attached the GoPro to the front splitter to get some super-low camera angles. A bonus was the sound - it's directly below the intake. This is fun to watch with the sound turned way up. You'll meet the CMC cars in the second lap.
entry 1096 - tags: track, hpr, video | | |  | September 16, 2013 - Track test for the active wing!
Once I had the car dialed in, I bolted on the active wing mounts. After some fiddling around, I got it set where I needed it and headed for the track. I did warn the chief steward that I was going to be testing a moving wing, so please don't black-flag me for a mechanical problem! I headed out for a couple of laps with a slow group so I could build my way up to full speed without getting rear-ended by a RUF turbo Porsche.
The wing looked stable enough under load, so I started to ramp up the speeds. It all looked good, and I was greeted with a big thumbs-up and grin from the steward when I exited the track. I then went out again with my fast group for the real test.
It works!
And it works really nicely. The car felt rock-solid under braking, with lots of stability. The various transient behaviors predicted by web forums failed to materialize, the car just felt as if it had upgraded brakes. It felt well planted on turn-in and it decelerated hard from 120+ mph. Unfortunately, the datalogger failed to record data for the test session so I don't have any comparative numbers. I'll be back on our small track in a few weeks, so we'll see how it does at 70 mph or so.
Video!
entry 1097 - tags: aero, testing, wing, active | | |  | October 2, 2013 - The master cylinder failed at the last track day.
It was an old salvage part that had been pushed hard - but I took it as an opportunity to upgrade. The previous setup used a 15/16" master cylinder from a Mazdaspeed. The Mazda 929 used a 1" master, and it bolts right on. Well, once you've reshaped the brake lines it does.
The result is a bit more braking effort and a firmer pedal. I figured I'd give it a try, so I installed a brand new 1" part. I took the opportunity to clean up the routing a little bit as well. The pedal is definitely firm, we'll see how it works at the track this weekend.
entry 1098 - tags: brakes, interchange | | |  | October 8, 2013 - And out it comes.
The L33-based 5.3 has done excellent work in this car, but it's done. A 6.2 LS3 with a big cam is going to be in charge now. There's nothing wrong with the 5.3, it just doesn't have the low-end grunt of the big motor. I'm going to take this down time to sort out a bunch of other little things on the car. You know, while I'm in there...
entry 1099 - tags: engine, 6.2 | | |  | October 10, 2013 - How hot did the transmission tunnel get?
Hot enough to melt this plastic check valve. This valve is supposed to prevent the buildup of pressure inside the trans with heat. It's obviously not able to do the job anymore, which would explain why the transmission had a tendency to leak from various seals. This will obviously get replaced.
In completely unrelated news, the exhaust system was sent off to Swain for ceramic coating today.
entry 1100 - tags: transmission, heat | | |  | October 17, 2013 - Did you know the LS engines have really nice valve covers underneath all those coils?
I was thinking of relocating the coils to where they wouldn't see so much heat and vibration, and the look of these is only reinforcing that.
The old engine has been stripped of all (or most) of the parts that I need, and the new LS3 is partially torn down in preparation to receive them. I'll be doing a cam swap in this next week, which is why the coils are off.
entry 1101 - tags: engine, 6.2 | | |  | October 24, 2013 - Cam swap time!
Working on this engine is almost like unwrapping a Christmas present - I'm discovering all sorts of new things. It's fun seeing how all the parts work together. You can look at diagrams and read about how the valvetrain works, but it's something else to actually peer down the cam bore and see the lifters tucked away. After so many years of Miata, Miata, Miata, seeing different solutions is interesting. It's also been a long time since I personally built an engine, I miss it.
The new "ASA" cam is now in place, with the timing chain back on and the front of the motor all buttoned up. All that remains is to flip the fuel rail over so the inlet is on the Miata-friendly side, change out the valve springs and install the new oil pan. Then I can start looking at putting everything back in the car.
By the way, the two dowels were supposed to help hold the lifters in place. I can't see how, I think that was a poor tech tip I found online. But they didn't do any harm.
entry 1102 - tags: engine, 6.2, cam | | |  | October 28, 2013 - Time to upgrade the valve springs.
As you may recall, I'm converting an LS376/480 crate engine into an LS376/525. According to GM Performance, the differences are the ASA cam and "higher rate" valve springs. So I called GMPP and got the part number for the new springs: 12586484.
Looking for these springs, I've found they've been superseded by spring 12625033. Fair enough, JEGS even sells the cam and springs as a kit so I picked one up. This handy little Comp Cams tool lets me swap out the springs easily without pulling the heads off.
entry 1103 - tags: engine, 6.2, cam | | |  | October 28, 2013 - Curious.
The new valve springs look exactly like the old ones. I checked further, and the 12625033 is the standard spring on an LS3. So I was swapping these out for nothing.
The older 12586484 part number was an LS6 spring, and they were typically yellow. Interestingly, they also have the exact same spring rates as the current LS3 spring, with the only difference being a max lift of 0.570" instead of 0.550".
Just for fun, I peeked under the valve covers of a true LS367/525 engine and what did I see? Blue springs.
Busted! GM doesn't actually change the springs on these engines anymore. Even if they did, the rates aren't any different. The max lift isn't an issue, as the 0.525" max lift is the same as that found on the 480 hp "hot cam".
So I wasted some time and money, but I learned something. Isn't that how it always goes?
entry 1104 - tags: engine, 6.2, cam, valve springs | | |  | November 6, 2013 - More preparation of the new engine.
The water pump has a couple of fittings for the heater. That's not needed here. When I installed the previous engine, I'd just installed rubber caps. These had a tendency to degrade over time, unfortunately. I never had one fail, but it was only a matter of time.
This time, I pulled off the fittings, tapped the holes and installed steel plugs. No failures here! If I ever decide to retrofit a heater, I can just screw in some brass nipples.
entry 1105 - tags: engine, 6.2 | | |  | November 6, 2013 - More preventative maintenance.
These motor mounts see a lot of abuse, both from a rambunctious engine and heat. Mine were in pretty good shape, but I figured it was much easier to change them now than later. I'm taking other steps to help them last longer - you'll see more of that later.
entry 1106 - tags: engine, 6.2 | | |  | November 6, 2013 - Another tweak.
The steering effort is pretty good on this car, but I've been wondering how it would feel with a bit less assist. This restrictor (on the left) will drop the pressure in the system a bit. Let's see how it works.
I've got one for my LS1-powered MG as well, as the NA steering rack in that car wants less pressure than the NB rack in the Targa Miata.
entry 1107 - tags: steering | | |  | November 6, 2013 - After a bunch of little individual jobs, adventures and solved problems, the engine is almost ready to install.
There's a new LS7 clutch and flywheel inside the transmission bellhousing. The oil pan came off again to check some clearances for another installation, then went back on. The new motor mounts are in, plus of course the cam and valve springs. I found a little squeak from where the rear cover had been just barely touching the crankshaft, and that's been sorted. The intake manifold insulation has been removed for hood clearance, and the fuel rail is flipped around to put the inlet where I want it. My dual oil pressure sensors are in place. A little bit of interference between the steering rack and the oil pan has been clearanced. We're almost there.
The only thing left is to reinstall the balancer, and for that I needed a special tool. The LS engines have been made by the millions over the last 16 years, but it's still a new and exotic engine according to most parts stores and tool manufacturers. It's almost impossible to find a balancer installation tool that is compatible. I had to build my own out of materials from McMaster Carr!
entry 1108 - tags: engine, 6.2 | | |  | November 11, 2013 - This should take care of the heat problems I've been experiencing.
The headers and the first part of the exhaust system have been given a Swain "White Lightning" ceramic coating. It's a big step up from the locally applied "ceramic" I had done years ago. That particular coat lasted about as well as my high-temp paint job did. This is much thicker and stronger.
entry 1109 - tags: engine, 6.2, ceramic, exhaust | | |  | November 11, 2013 - Future failure avoidance.
Prior to installing the engine, I spent a fair bit of time going over the wiring harness and ensuring it was well restrained but accessible. In a couple of spots, I was unable to avoid wires making contact with the block. In those places, I made sure the wires were protected. They're not quite in contact, but with all the vibration to come they need something.
entry 1110 - tags: engine, 6.2, wiring | | |  | November 13, 2013 - And the engine is in!
This makes it sound a lot quicker than it really was, but after a bunch of fiddling about and checking I have it installed. And now comes the fun part - the wiring.
entry 1111 - tags: engine, 6.2 | | |  | November 13, 2013 - Because the Targa Miata has a stripped out interior and no HVAC system, I've got some space that's not usually available on the street cars.
I've decided to mount the engine computer to the interior side of the firewall so it'll stay a bit cooler than being underhood. This means I have to pass some significant cables and connectors through the firewall. I don't have any wire grommets that size.
This panel is the answer. It has a clip on the backside to lock the bottom into place and the top is bolted down - it's upside down here. The wires are all centered in the grommet before the second half is riveted in place.
entry 1112 - tags: engine, 6.2, wiring | | |  | November 13, 2013 - Wiring fun!
This poor car has been through a lot. I stripped out the harness when I built it, and modified it for my purposes. When the original V8 conversion was done, the engine wiring came from a 2002 Firebird - but had already been installed in another Miata. Then I kept modifying and tweaking things, changing the harness around further. Wires for electric windows, cameras, dataloggers, extra sensors, goofy rear wings and the like. It's a bit of a mess.
With the new engine, I'm installing a standalone engine computer and wiring harness. I'm taking this opportunity to revisit all the wiring in the car, removing the leftover bits from the four cylinder build and that junkyard GM stuff. This under-dash harness will be greatly simplified, and the whole thing should be much more robust when I'm done.
It sure looks horrific when it's unwrapped and spread out! The junkyard GM parts are still wired in, and the new GM wires are also looped around like snakes in this shot. Fun stuff.
entry 1113 - tags: engine, 6.2, wiring | | |
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