| MIATA BUILD |
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 | |  | May 27, 2011 - The wiring is getting close!
It doesn't look like a lot of progress, of course. But wiring a car like this is a series of small jobs - hooking up the reverse lockout solenoid, tracing the oil pressure sensor wire through the harness, etc. But it's close!
entry 838 - tags: wiring, conversion | | |  | May 27, 2011 - The big engine needs a little more power to spin over than the four cylinder did.
The little lightweight PC680 was happy to do the job in 2008, but this year I'm going to run an Optima with more than double the cranking power.
entry 839 - tags: battery | | |  | May 27, 2011 - One of the cool things about GM is that just about anything with a part number can be ordered.
Case in point: this plug for the engine coolant temperature sensor. I don't know why it was removed from the harness by a roving parts scavenger, but a call to the local dealer yielded a replacement on the shelf. Try that with a random Mazda connector!
entry 840 - tags: wiring, conversion | | |  | May 27, 2011 - I found these while unpacking some of the conversion parts.
They're not needed yet (or at all, really) but I couldn't resist sticking them on for a few minutes.
entry 841 - tags: engine | | |  | May 27, 2011 - In preparation for the first noise from the car, I've loosely installed the exhaust system.
I'll have to take it out again after the driveshaft arrives on Tuesday, but it was just too pretty to leave on the floor. Besides, this way I can plug in the O2 sensors.
entry 842 - tags: exhaust, conversion | | |  | May 27, 2011 - Getting closer to that first firing of the engine.
First, I have to make sure there's fluid in everything. The T56 uses ATF for lubrication.
entry 843 - tags: transmission, fluids | | |  | May 27, 2011 - It's alive!
Obviously, the intake system is temporary. But it makes noise!
First, I unplugged the engine computer (PCM in GM-speak) and powered up the electrical system. I then cranked the engine until I had oil pressure. This took a long time because the pump had to fill the oil cooler as well as the completely dry engine. It probably only took about 30 seconds total of intermittent cranking, but it seemed like forever. Finally, the gauge jumped up.
I pressurized the fuel system and checked for leaks. Then it was time to take a deep breath and hit the key. The car tried to stumble into life, but it wasn't happy about it and was acting like it had very low fuel pressure.
I realized I couldn't hear the fuel pump priming when I turned on the key. Checking out the wiring looked good, and hot-wiring the pump woke the engine up on 6 cylinders. I'm guessing the VATS anti-theft program got turned back on in the PCM so it won't run the pump. I'll turn that off again soon, but in the meantime I can run with the pump hotwired.
The exhaust system isn't bolted together and I have no cooling fan wiring yet - but it runs!
entry 844 - tags: conversion | | |  | May 29, 2011 - More wiring!
I could do it faster, but I'm trying to build a car that will survive a week of stressful days without failing - and if it does, it should fail gracefully and be easy to debug. This means a lot of time looking at how I'm going to do something, seeing if there's a better way besides the initial obvious solution. Sometimes yes, sometimes no.
I wired up the fans yesterday, for example. I needed a good power supply for the second one, as I've learned in the past that these particular fans can pull over 20A each on startup. The usual way is to run a wire with an inline fuse. But there's a spot in the factory fusebox that isn't used on my car - it's for the ABS system. It also happens to be right beside the fuse for the main fan. So I removed the fusebox and pulled the appropriate connector off the bottom. Turns out the wire I needed simply wasn't there, but there was a spot in the connector plug for a spade connector. I pulled one out of an unusued plug and slotted it into place. Now I had a factory-designed 30A power source! I ran that down to a new relay which is triggered off the main fan. It worked out pretty slick. I even used the same wiring colors used by the main fan so that I know that yellow is a fan power wire, for example.
I also identified a fan override wire that will let me kick on the fans manually without waiting for the engine to get up to temp. I have an idea for that one, we'll see if it works out.
I also wired up the driver's side O2 sensor which needed extended wires and tightened up all the exhaust system connections. The car sounds pretty good. The PCM hasn't figured out how to idle yet so the car won't stay running without a bit of attention to the throttle pedal, but that's normal for the GM computer when it's lost power.
The new shocks ands the driveshaft should both arrive on Tuesday, and it's my goal to have the car ready for them when they arrive. It's looking promising.
entry 845 - tags: Wiring, conversion | | |  | May 31, 2011 - Visible progress!
I decided the wiring was in good enough shape to install the dash. The harness is still pretty accessible, but it's more awkward of course. It was quite a wrestling match trying to get the dash back in, it's the first time I've tried that while there was a windshield in the car.
The navigator's footrest is in, the defrost system is hooked up, the switches are wired - it's getting closer. There's no functioning speedometer in the car at the moment but with the rally computer that's not a big problem. I'll address that later.
I did realize that my current fan wiring does have a vulnerability - the right fan is completely dependent on the left fan for a trigger. If something goes wrong with the left one, I'll lose both. I know how to wire this so that both fans are independent, but I'll deal with that later.
entry 846 - tags: interior, conversion, wiring | | |  | May 31, 2011 - The engine bay is looking a bit better!
I was able to sort out an intake system that allows the use of both the hood and the driver's headlight - hopefully. It's not ideal, but it'll do for a start. I've also cleaned up and anchored the wiring. Other than a lack of a hood prop, this is pretty much ready to go.
entry 847 - tags: engine bay, conversion | | |  | May 31, 2011 - It's amazing how many small jobs eat up time.
I have a new set of Corbeau harnesses for the car, as the old ones were expired. So I need to set them up for length. It's not a big piece of work, but an hour or so of fiddling around was an hour I couldn't spend on something else.
entry 848 - tags: safety | | |  | May 31, 2011 - Aero!
The car will be spending more time at high speed than before, so I'm going to do a bit of work to stick it to the ground. I'll be doing a spoiler on the trunk lid, and this air dam will help balance it out. The relatively high ride height of the car will make the air dam less effective than it would be on a track car, but you work with what you have. The part is made of flexible polyurethane so it'll deal well with impacts.
Due to that higher ride height, it will probably be difficult to balance the downforce of a wing. Still, if I can get time, I'd like to test that.
entry 849 - tags: aerodynamics | | |  | June 1, 2011 - The installation of the V8 is going to require the reworking of a few things.
When I first built the car, I installed the rear subframe brace from a 2003. This not only stiffened up the rear of the car, it also provided protection. That wasn't just theoretical, inspection after the race showed how much abuse it had soaked up. Granted, I had some other problems that were causing this, but still.
In order to make room for the V8 exhaust, I had to go to the less beefy version of the brace used from 1999-02. The two forward cross braces are gone because the exhaust pipes hang too low - and that means they're going to be susceptible to damage. I've got some ideas, but it's one of the things I'll have to address.
entry 850 - tags: exhaust, conversion | | |  | June 1, 2011 - I've been working on the car quite a bit over the past couple of weeks, and it's become more intense for the past couple of days.
That's no surprise given the upcoming track test. So I stopped taking pictures as I installed suspension, bled the brakes, installed the seats, bolted on the roof, etc - but check it out! It's together. That means it's time for the first test drive.
It wasn't an epic drive, just a half mile down the road and back. The goal was just to determine that all of the various systems were working. This car has undergone quite a bit of change since it last turned a wheel under its own power. So how was it? Good! Not perfect, as there were a few little problems: a seeping oil fitting, a dragging rear brake, a bit of interference between the steering column and a heat shield, and low power steering fluid. But those are to be expected and were quickly sorted out. There were no real concerns. The car runs well, shifted well and the chassis still feels like the Targa Miata. Woohoo! Now that I know nothing terrible is going on, I'll exercise it a bit more next time. I'm still breaking the engine in, though.
By sheer coincidence, the first drive of the car took place almost exactly four years ago. I then spent an extra year honing the car for the 2008 Targa. I've got a shorter schedule this time, but the car's much more complete.
entry 851 - tags: first drive, v8 | | |  | June 1, 2011 - The test drive was done without a hood.
The current intake system won't fit under it without some trimming! I'm going to try a slightly different tack first. I've got a few ideas...
entry 852 - tags: intake | | |  | June 6, 2011 - A few days of very hard work and no updates.
So let's catch up, shall we?
First, the new intake. This has been a bit of a challenge because the throttle body is 4" and the MAF is 3.5". On the rest of the cars built at FM, we've used a 4" MAF. So I've had to play with a couple of different tubing sizes. The previous iteration dropped down to 3.5" then back up again, but there's no reason for that and it put a big 4" tube in the tightest spot. So I stopped by a muffler shop for a tight 90 degree mandrel bend of 3.5" tubing and assembled this setup.
Yes, the filter is right above the left header. I'll work on that later. Right now, the focus is getting the car to the track on Saturday.
entry 853 - tags: intake, conversion | | |  | June 6, 2011 - Unfortunately, even my "low profile" intake wouldn't fit under the hood.
Then I discovered that, even with no intake at all, the hood wouldn't close. I spotted the power steering reservoir as a problem. But removing that didn't solve it either - the throttle body hit the hood!
After checking with Tyler, the fabricator who builds the V8 cars at FM, I found out this was normal. Some of the hood structure would have to be removed. So I proceeded to make copious amounts of noise. And finally, the hood closed.
entry 854 - tags: hood, intake, conversion | | |  | June 6, 2011 - Lots of final details in the last day before going to the track.
Including some more test driving, and a problem is appearing. The car's running oddly, with a lot of hesitation at times. After some poking around with the wiring, I finally got the OBD-II port to work and discovered that neither of the O2 sensors are providing a real signal. They're flatlined at 0.455v. Turns out, that's the same reading you get if the sensors are disconnected.
Some more poking around at wiring and all the connections appear to be good. Bill and I are doing a bunch of research to see what normal O2 wiring readings should be, we're seeing some things that don't quite make sense. For example, it seems the GM computer feeds around 5v down the "high signal" line and 0.455v less down the "low signal" line. Is that right? I'm still trying to determine yes or no.
entry 855 - tags: wiring, conversion | | |  | June 6, 2011 - Before dropping the car to the ground for the last time, I decided to check the weight.
I'd been hoping for about 2300 lbs wet. Well, not quite. It's closer to 2400 by the time a full load of fuel is taken into account - I was only at around 1/4 tank. Assuming there's room for another 8 gallons of fuel in the car, that's about 50 lbs and it'll all land on the rear wheels. That brings the fore/aft weight distribution to 54:46. By the time I've loaded in a spare and the tools in the trunk, I think the final balance should be pretty good. It's interesting to note that the first time I weighed the car in the initial form, it had a 53.8% front weight bias. But by the time it went into the trailer for the race with a spare tire and tools and the like, that had changed to 50.2% front. So I'm not that far off.
The reason I was hoping it would be 2300 lbs is that I was assuming a 200 lb weight gain over the 2100 lb naturally aspirated form. But when I think back, I think it was closer to 2200 in race weight. There will be a few more changes, but probably nothing drastic.
entry 856 - tags: weight, conversion | | |  | June 6, 2011 - Track test!
I took the car out to High Plains Raceway, which was coincidentally the last track it ran on before coming apart for the big personality change. At that time, it was very nicely sorted with just a bit of turn-in understeer from the new diff and a shock that was low on fluid. The engine was in fine form.
Well, the car looks the same. But the noises coming out are quite a bit different. After my first session, I had to fix a leaking brake caliper. The Wilwood front calipers have a fitting that screws into the caliper, and the bleed screw threads into that. The leak was where the fitting goes into the caliper, and it was a gusher. It took me a while to figure out what happened - I think when Adam was dismantling the car, he loosened the bleed screw to drain the brakes. But the fitting backed off instead. When I re-bled the system, I used a pressure bleeder that only puts 10 psi through the system so I didn't discover the loose fitting. No worries, it was easy enough to tighten up once I found the problem and I hadn't really lost that much fluid.
Unfortunately, the hesitation problem was still pretty bad and the engine was down on power. I'd estimate it at around 230-250 hp at the wheels. Not shabby, but about 150 hp low. I played around with a few things but wasn't able to identify anything with my meager resources at the track. So I worked on sorting the chassis.
In the second session, I decided the car was understeering too much. There was also a clunk from the front end under hard cornering. I softened the front sway bar and found an alignment bolt that was not loose but not tight enough. I also discovered that my throttle pedal was only allowing about 3/4 throttle, something I was sure I'd checked! Adjustment ensued.
The third session didn't show a real difference in power, disappointingly. Once in a while, the car would clear its throat and just leap forward - even at 100 mph, it was enough to bounce my head off the headrest when that happened. But not consistently. But the understeer was almost all gone and the car was mobile again. The clunk was also gone. So that's a success.
I decided to call it a day after that. I still had another three sessions or so to go, but with the engine misbehaving there was no point. The handling was in good shape and I'd confirmed the rest of the car was working as intended. There are still a number of small things to do, such as move the shift lever forward about 1" so it's easier to reach in 2nd and 4th gear. But as long as I get the engine happy, the car's in decent shape.
entry 857 - tags: testing | | |
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