| MIATA BUILD |
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 | |  | 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 | | |  | June 8, 2011 - Progress.
The O2 sensors have now reported for duty. It's quite possible that one of them was incorrectly diagnosed as wrong, thanks to some confusion on my part between Bank 2 Sensor 1 and Bank 1 Sensor 2 in my logging program. Possible, but not certain! Regardless, I can read them both happily now.
Unfortunately, that hasn't solved the problem. The sensors are displaying what I can feel - the car is going lean for 15-20 seconds, then rich for 15-20 seconds. One interesting thing is that the car still isn't going into closed loop as far as I can tell. I haven't spotted the problem in the datalogs yet, but I'll get there.
entry 858 - tags: conversion | | |  | June 9, 2011 - A-ha!
Bill and I spent some time on the car last night, and determined that the injector duty cycle is changing when the car goes rich. That means it's not a mechanical problem such as a fuel pump, but bad instructions from the engine computer. We also discovered that unplugging the MAF makes the car go rich, which points towards a real problem with the programming.
After discussing this with Steve from V8Roadsters, it seems that our computer was reflashed for the wrong type of MAF. Unplugging it forces the computer to go back to the static tables, but they're set up for sea level and not 5000' of altitude so they're too rich. To add to the fun, the computer was given a custom operating system so our copy of HP Tuners will no longer communicate with it.
I've been put in touch with the programmer who set this thing up, and hopefully we'll have an answer soon. I've got another track day scheduled for Saturday, and I'd love to have the car on the track in full health. I'm not confident it'll be sorted in that time, but at least we know where the problem is!
entry 859 - tags: conversion, programming | | |  | June 13, 2011 - Track test again!
This time, I was at Grand Junction Motor Speedway. It's a very familiar track and I've got a good library of lap times there, so it's a good test on if the car's any faster or not.
I went back and forth with the computer programmer, sending in a number of logs for various drive cycles. The 5000' elevation doesn't actually make a difference, of course, as the computer is running off a MAP sensor with the MAF unplugged. It's just tuned wrong. Since I didn't have the ability to make any changes, there really wasn't anything I could do. The computer is going back to him to be unlocked (again) and hopefully a new tune. I almost nixed the test session on the track because, even with the MAF disconnected and the car running in closed loop, it wasn't completely happy. On the morning of the track day, however, I decided to run it anyhow.
The track is tight, with slow corners connected by short straights. Definitely not a place to sort out high-speed handling although there is one section that's 70 mph in a big sweeper. The biggest problem is that there are very few high-speed corner entries. But it's a well-known venue.
The car was particularly unhappy under braking. Last year, before the engine swap, I'd found the rear brakes simply weren't contributing enough. And they're still not. On my first session, I managed to hit 75 mph in the fastest section and then had to get fairly creative while trying to gather the car up for an off-camber braking zone. Usually, we can't run more than about 70 mph through there! I held it together, but also locked the front wheels in the process. The tires were already slightly flatspotted but after that episode they felt completely square. So they had a tendency to lock very easily. The car was also understeering on the tightest corners, likely due to the clutch-type differential. It was similar to what I'd seen with the OS Giken diff with the four-cylinder.
Still, even with some handling quirks and a driver that really wasn't doing a great job behind the wheel, I managed to hustle the car around faster than ever. Not a lot faster due to the braking problems, but it counts. My fastest time was a 1:03.725 before I flat-spotted the tires, and it got worse from there. My previous best was a 1:03.796. Like I said, not a lot faster! It's interesting to note that in 2007, the first time this car took to the track, I turned a 1:03.733 in the Seven.
As always, the GM diff hooked up extremely well. I could light up the rear coming off a corner, but it took more effort than you'd expect. That might partially be due to the rich air/fuel mixture cutting power, but it's in line with the sort of traction this diff provides.
There's more time in it with round tires and a driver who's settled down a bit. By the end of the day, I knew the tires were toast so I just started playing around with leaving black stripes around the track like the child I am. You have to, right?
I did have one exciting moment. In my third session, I was just coming off the last corner on to the straight when the engine died. A half-second later, I got a big whiff of fuel. I immediately cut the ignition (the fuel pump control in the engine computer was disabled by the tuner, so it's run off the ignition) because I had a feeling I knew what had happened. And I was right. The push-on fitting for the fuel feed had come apart popped off. It happened a couple of times during the build and I suspect it was damaged or defective. It had been good for a while, though. When that happens, the fuel feed sprays 60 psi fuel all over the engine. I was still moving fairly well and right by the pit entrance, so I brought it into the pits and bailed out to open the hood right away. Luckily, no fire. Whew. A couple of hours later, I had a replacement and everything seems to be working as intended. We've used these fittings on a lot of cars and never had a problem.
So, not a bad day. I'm going to change out the spring rates to the expected Targa setup and set up the ride height for the rally. Then I'll start to really fine-tune the handling. I'm also going to pull out the engine computer and send it back to be reflashed. That will let us tune it properly for this engine.
entry 860 - tags: testing, fuel, V8 | | |  | June 13, 2011 - The new wheels are here!
The selection was pretty tough, actually. I'm allowed to use a total of 8 tires during the race, so I need 8 wheels. Given that I'm going to run a 225/45-15 (more on the tire selection later), I wanted something wider than the 15x7 wheels I have now. That's a shame, because I have a full set of 8 of those. Oh well.
So I wanted either a 15x8 or 15x9. At Flyin' Miata, we have a collection of both. I decided to go with the narrower of the two because it'll give me a bit more sidewall flexibility for following the rough surface. That narrowed it down to three basic choices: the TR Motorsport C1, 949Racing 6UL and the new Konig Wideopen. The C1 is the least expensive of the lot, but the heaviest by several pounds. The Konig is a brand new wheel and looks to be a pretty good value, but it's unproven. More importantly, we didn't have any I could borrow so I'd need a full set of 8 of either.
Meanwhile, the 6UL is both the most expensive and the lightest at 12.0 lbs on our scale. It also seems to be pretty strong. But we have a set of 4 of them at FM, so I only needed 4 new ones to get my full complement. That makes them the least expensive option really.
The black is a satin sheen. With polished lips, they'd look pretty killer. Better than other black/polished 6ULs I've seen that had a glossy center. They're not going to stay black, though. The car needs white wheels, and Emilio at 949 says the black is the best base color for paint. I just have to decide if I'm going to use proper car paint or use Duplicolor wheel paint. The advantage of the latter is that it's easy to touch up should the need arise.
I can hear howls of protest now about my painting plans. I'm okay with that.
entry 861 - tags: wheels | | |  | June 15, 2011 - Time for some paint on the wheels.
I decided to paint them with rattlecan paint instead of proper car paint - even though I had all my painting gear out for working on another car. The main reason was that it's easy to patch if it gets chipped. I'm using Duplicolor wheel paint, and I've had good luck with it in the past on three other sets of wheels. It's also just plain easier to deal with.
First, I scuffed them up a bit with a Scotchbrite pad, then wiped them down with wax and grease remover. Emilio at 949Racing had told me that they didn't need to be scuffed, but it can't hurt to give the paint a bit more to adhere to.
Unfortunately, the local auto parts store only had one can of white. It would have been more than enough to do just the faces, but when you're trying to paint the barrels of 8" wide wheels that just doesn't quite do it. One can did this - they're covered, but a little patchy. I'm not too worried about that, the inside of the wheel isn't that visible. I shall obtain another can later and do the front faces. Those will be blinding white.
entry 862 - tags: wheels | | |  | June 17, 2011 - The tires are here!
Long-time readers may remember the decision process for the tires in 2008. I finally went with a 205/50-15 Toyo RA1, and I'm happy with that.
But the rules have changed. Specifically, all tires must have a minimum treadwear rating of 140. That means no more nice sticky R compound tires. This leaves me with what I call the "Azenis class" of tire, the gummy street tires designed for autocross. We are allowed to run 8 tires this time instead of 6. Given the ability of this car to spin the wheels, that may not be a bad thing.
The tire size was fairly easy this time around. With my new power/weight ratio, I want as much tire as I can get. And in the stock tire diameter, that means a 225/45-15. In that size, I have the choice of two tires: The Hankook R-S3 and the Toyo R1R. I'd love to be able to run the Dunlop Star Spec, but it's simply not available in the size.
Asking around, it appears the Toyo is a better tire in the wet and possibly overall. So, 225/45-15 Toyo R1Rs it is! I like to call them "pirate tires". Arrrr!
There actually were a couple of other options out there. The Toyo T1R comes in a 245/35-16, but that's not the right tire for the job. The R1R comes in a 245/35-17 that could work, but it needs a 17x8 wheel at minimum and preferably something wider - which isn't really available. So we're going with the light and tested setup we have.
entry 863 - tags: tires | | |  | June 28, 2011 - Remember the fuel line fitting that popped off?
I did some digging after the last failure on the track and discovered I wasn't the only one who had experienced this. In fact, one of our customers had even had the same experience. There was definitely a problem.
Luckily, I also came across a new design from the same manufacturer. It wasn't even production yet, but a fellow on the LS1Tech forum had a pre-production piece. I spent some time on the phone with Russell fittings and managed to get my hands on the part number for the new design. We returned all the stock of the old parts that were on the shelf at Flyin' Miata and the new ones have just arrived.
That's the new one on the right. As you can see, it screws together instead of relying on a piece of plastic. Much more reliable. Even though the factory uses a plastic clip design, there's something about this particular implementation that just isn't right. Russell makes a big deal about proper installation when you call their tech line, but even then they fail - and the factory ones don't need the same installation procedure they call for. The new one is a vast improvement. This should be the end of surprise fuel baths for the engine.
entry 864 - tags: fuel | | |  | June 29, 2011 - Good news!
The engine computer is back from being reflashed, and it's working far, far better than before. Many more horses now live under the hood. It's not yet perfect, but it's now running in closed loop and with long term trim so it'll get better. Best yet, I can now get in to the computer to tune it. So we're well on the way.
I also discovered an advantage to flexible air dams. There's a piece of road nearby that was torn up for construction and hasn't been repaved. There's a slight drop down to the gravel/dirt level. Well, when I (purposefully) took this at a high rate of knots, the air dam bottomed out and became a snowplow. A truly impressive cloud of debris was raised. Back in the garage, there's no damage to the dam and a few screws that have pulled out. I was going to replace those with bolts anyhow, so no harm done. And yes, I do need to lift the car up. I'm pushing it right now to find out where the weak areas are.
entry 865 - tags: power, V8, air dam, aero | | |  | June 30, 2011 - Nancy is the sister car for the Targa Miata at the race.
It's almost ready to run as-is, but it does need a bit of extra rally prep. The most obvious is the Terratrip rally computer.
Why does this car run a Terratrip while the Targa Miata runs a Coralba? Cost. Eric got a great deal on the Coralba five years ago, and it's a great computer. But this fully-featured Terratrip is far more affordable and has proven itself in club competition over the years. The one thing it's missing that would be nice to have is the "pilot speed" function, which tells the crew how many seconds they need to gain/lose in order to hit a specific average speed. Still, the average speed display will work well.
entry 866 - tags: Nancy | | |  | July 6, 2011 - More useless equipment.
Well, hopefully useless. If all goes according to plan, these will never do us any good. But given the performance of the car, it's better safe than sorry.
For those who don't recognize them, they're HANS devices for Janel and I. If the worst happens, they'll help keep our heads attached to our necks. Not cheap insurance, but better than the alternative.
entry 867 - tags: safety | | |  | July 6, 2011 - A new intercom for the Targa car.
This one, a Peltor FMT120, has a few features the old FMT100 didn't. Aux in (for a phone), separate volume controls, etc. Most importantly, it has an audio out. When combined with the new video camera that arrived last week, this means we'll be able to have Janel's instructions as audio for the in-car footage instead of just engine noise. That should make it a lot more interesting to watch.
The old intercom will go into Nancy, the sister car on the team.
Progress on the car should resume shortly. Lots of fine-tuning to do.
entry 868 - tags: intercom, video | | |  | July 9, 2011 - Since neither my helmet nor Janel's came with HANS anchors, I had to install them myself.
It's not a terribly difficult job. As you can see, Janel busied herself with personalizing her HANS device as I drilled into her helmet. Well, we have to be able to tell them apart, don't we?
entry 869 - tags: HANS, safety | | |  | July 11, 2011 - Yup, that one's done.
That's not just cord you can see, but steel belt. In three places.
entry 870 - tags: tires | | |  | July 11, 2011 - The car's on the lift again, getting a number of upgrades.
New 550 lb front springs, an increased ride height all the way around, the new intercom, some heat shielding, air dam repair, skid plates (if I get time this week) and the like. I'm also removing the old sponsorship stickers in preparation for this year's batch. Yuk, that car needs a wash.
entry 871 - tags: work | | |  | July 12, 2011 - One of the items on my "fix it" list was heat insulation.
That transmission tunnel gets a bit warm. So I turned once again to Reflectix. It's basically heady-duty bubble wrap with an aluminum coating. It weighs nothing at all, is completely waterproof and costs about $20 for 50 square feet. Perfect. On this car, I covered the inside of the transmission tunnel on both sides and on top back to the gearshift.
I use a waterproof foil tape to attach it to the car. I've found that, as long as you give it a clean surface to attach to, this stuff will never let go. In fact, there's still some of the tape from the previous heat shielding stuck on the bottom of the car where I can't get it off!
entry 872 - tags: insulation | | |  | July 12, 2011 - The original hood prop wouldn't fit the engine bay anymore.
But I have one of the old Flyin' Miata shock tower braces in my "stuff for the Targa Miata" pile, and we used to offer a hood prop that mounted to those. So I installed it. Voila, problem solved! And an increase in front end rigidity, too. There are some who don't think a shock tower brace does anything on a Miata, but you can see the distance between the towers change as you lift the car up! That's even true on my caged, seam-welded car. Regardless, even if it didn't do anything, it does make an excellent hood prop mount.
entry 873 - tags: stiffening | | |  | July 13, 2011 - Check out the race wheels!
It's a pretty cool looking car with the crazy Toyo R1-R tread pattern and the white wheels. The ride height is set fairly tall as well, to give me room to deal with the roads. Right now, it's at 13.5" front and 14" rear. Current spring rates are 550 front and 450 rear. That's a fairly high rear spring rate, but this car has always needed more rear spring than usual for some reason. It could be the way it gets used! Normally, I'd use a 375 or so to match those fronts. There's a V8 customer car at FM with that exact setup and it's a sweetheart.
On the road, the suspension feels pretty good. The car hasn't been aligned since the ride height increase and a changed lower control arm, so I've not gone far. But it does seem to have the right suppleness I need. One thing I've learned about the AFCOs since the 2008 race is that they love stiff springs. It's almost as if they ride better with the heavy springs than they do with the light ones as you move into the higher damping settings. I'm looking forward to running this car at speed.
I've also moved it to my home garage for a while. I find it easier to work on the car at home instead of staying late at work. That's the theory, anyhow. I've got a good list of jobs to do on the car. Little stuff, but it still needs to be done and it all adds up.
Driving the Targa Miata and the LS1-powered MGB back to back also illustrates that I need to spend more time tuning the Miata's engine. It doesn't feel anywhere near as strong as that MG does, despite a similar weight on the two cars.
entry 874 - tags: suspension, wheels, tires | | |  | July 16, 2011 - How's this for a cool garage?
The two Targa cars, the Seven and the LS1-powered MGB. My garage currently has a very high power/weight ratio.
entry 875 - tags: cool cars | | |
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