Targa Miata
October 15, 2008 - The weekend after the wet and foggy autocross, I was at it again.
No, you just can't have enough racing. This time, though, I was driving Elvis. That's a Miata put together at Flyin' Miata with an LS1 engine - an all-aluminum Corvette engine, basically. Brandon and I were sharing the car so it ended up being a real driver's competition. I managed to beat him, but by less than 0.3 seconds.
So why is this on the Targa site? Because I think this would be an absolutely killer Targa car. Not this particular one - the suspension is too track-biased - but this engine in the Targa Miata would be a beast. The engines start at about 300 hp/300 ft-lb and go up from there, and the overall weight gain is under 200 lbs. More importantly, the car has almost endless torque and would catapult itself out of corners regardless of what gear you're in. The biggest problem would be getting enough nerve to unleash the beast! That plus the increased rear tire wear.
Actually, the biggest problem is that I'd have to run in Open class, up against the factory teams and the big guns. But this car was so much fun to drive, I think I'd be willing to take that penalty...
entry 634 - tags: v8
May 7, 2009 - Open wide!
This is the lineup of cars at the Mitty. The white one (without a lurid Martini paint job) is a car from Grassroots Motorsports. When I was at the Mitty last year, I helped install a turbo on the car and double its horsepower.
Beside that are two V8-powered cars, and of course the Targa car. I spent a bit too long standing in close proximity to the V8s.
Like every Targa competitor, I spend a lot of time trying to figure out what the perfect car for the event would be. It needs to have a combination of small size, light weight and speed - and the older the better to take advantage of the longer base times. A BMW 2002 is a very good choice and it's no wonder the car's done well the last few years. I'm thinking a Mk1 Escort with a 1600 BDA might be able to run in class 4 and still have the same power/weight ratio as the Targa Miata as well as factory-developed rally parts - but much, much more time to finish a stage without penalties.
My own class - 8 Modified Small - is a tough one to be competitive in. The difference between the Large and Small speeds is minuscule, so the low-power smaller engine does me no favors. However, I can't increase the engine size more than 20% so the car's stuck there. The fairly new build date of the car hurts too, but dropping back to class 7 would mean using the weaker differential from the 1.6 chassis as well as the smaller engine and a bunch less torque.
Assuming the same level of driving ability - the car certainly is capable of going faster in a different set of hands - the best way to make the car more competitive might be to take it into Open class. Yup, the deep end. The handling is good already. What it needs is blasting power. The ability to teleport up to the maximum 200 kmh at every opportunity.
And that means a V8. Less than a 200 lb weight gain and an extra 200 ft/lb of torque at idle. Heck, probably more. Drop in an LS3 crate motor and there's 430 hp with the factory engineering to run for a couple of hundred thousand miles. The small size and nimble handling of the Miata but with the acceleration of, well, just about anything. The biggest problems would be putting the power down and keeping the driver from wetting himself.
I seem to have rather wandered off on a tangent here, but the logic works. Doesn't it? It's probably just as well we're not liable to be going back any time soon.
entry 675 - tags: Mitty, V8
May 10, 2009 - Another track day!
This time, the Targa car sat in the trailer and I drove Elvis, the LS1-powered bar (back in full health) instead. It took me some time to come to terms with the car. It simply seemed squirrely. Not so much under power - it behaved exactly as expected then - but during braking and cornering. It's the first time I've set up a car with this particular tire so that's part of it, and it has good brakes but without adjustment options.
But what I finally realized was going on was that I was expecting its cornering and braking ability to be in line with its acceleration ability. It thunders down the straight like the turbocharged Westfield beside it, but it still corners like a Miata and not a 1300 lb featherweight. So I had to bleed off more speed for the corners, and my Targa braking points didn't work because the car weighs 400 lbs more and was going considerably faster. So the problem wasn't the car's traction, it was simply that I was asking too much of it.
Of course, another problem was the red mist. My first session out, I'd blown away the fastest Miata to ever run the track. So I was hoping to beat the track record for Miatas by as much as possible. I did, by a considerable amount. And now that the mist has faded, I realize that I need to spend some time tuning this car on a big track, where I can get it settled on a long sweeper to set the basic handling balance and then tune the transitions from there. The car still handles well, I just want to bump it up to the top level. Not bad for a street car though.
I took Janel out for a few laps. She was impressed by the violence. It would be a very effective Targa car, but it would take a different driving style than the current setup. The fact that it was faster in street trim than the Targa car is in race trim is a good sign.
Janel also took her own car out for a couple of sessions. Now that she's experienced the Targa car at its best, she was quite adamant about the shortcomings of her previous ride. "I miss my tires! I want my brakes!", she informed me. Oh boy...
entry 678 - tags: other cars, v8
November 4, 2009 - Temptation.
Okay, I was really just doing some suspension work on the car and the plastic V8 mockup happened to be used for something else. But wouldn't these two work well together?
entry 717 - tags: V8
February 14, 2011 - The V8 Roadsters front subframe is here - and it's a beautiful thing.
We also received the differential mount. More V8 Roadsters parts are coming, but the subframe will allow us to double-check our transmission tunnel modifications and move forward with the work.
entry 793 - tags: subframe, V8 conversion
March 2, 2011 - The transmission has arrived.
It's a T5 with the following ratios:

There's always some concern about the strength of a T5 in this sort of application. However, it's the same one used in the V8R Spec series. The big advantage we have is weight - there's a world of difference between launching a 3000+ lb Mustang and our 2300 lb Miata. We will be adding a cluster support to help it out.
entry 796 - tags: transmission, V8
March 28, 2011 - Cue the happy dance!
The freshly built engine has arrived from V8R Spec. I really want to unwrap it and get fingerprints all over, but I know it'll just look like every other V8 and it's well protected at the moment. I can't wait to fire this puppy up.
entry 797 - tags: engine, v8
March 28, 2011 - Time to get back to work on the car.
Tyler has been busy working on another V8 conversion, but now it's the Targa's turn. He used the plastic engine on the subframe to confirm we have the clearance we need for the bellhousing, and now everything can be welded up.
entry 798 - tags: v8
March 28, 2011 - The transmission tunnel modifications are complete.
The tunnel is actually big enough to swallow the large T56 transmission, even though we're going to install a T5.
entry 799 - tags: v8
March 31, 2011 - Before painting, the car got a coat of sealer in the transmission tunnel as well as primer along the seam welds.
I was conflicted about using the sealer on the tunnel - it'll make it harder to fit heat insulation such as the Reflectix I used earlier, but it'll protect the metal. I'll just put insulation inside the car this time.
entry 801 - tags: v8, tunnel
March 31, 2011 - The radiator was specifically designed for V8 conversions.
It's got the correct size inlet and outlet for the big motor and is a very efficient dual-pass crossflow design. The radiator mounts have to be altered to move the rad forward as much as possible. This involves cutting and welding the stock bits and lots of test-fitting. To avoid damage to the radiator, I wrapped a layer of cardboard around the core.
entry 803 - tags: cooling, v8
April 19, 2011 - Everything's here.
It's time to start the build. And just in time - the car's supposed to be in Atlanta for the Mitty vintage races. It has to be on the trailer in a week. Can it be done?
Maybe. Between the long period of disassembly, the fact that it's a built engine from a different source than FM's usual crate motor and the different transmission, I've found a lot of little items that have been overlooked. Some are simple to fix, such as the missing motor mount bolts. Some are a bit more complex, such as the remote oil filter mount that was forgotten. Still, if all goes according to plan the engine will be in the car tomorrow.
entry 804 - tags: conversion, V8
May 20, 2011 - Finally, the drivetrain is all buttoned up and ready to install.
I installed the headers as well as some of the power steering plumbing while I had easy access.
entry 831 - tags: Drivetrain, v8
May 20, 2011 - Much better - the engine and transmission snuggled into place.
The V8Roadster rails are laser cut, so the bolt holes were in the exact same location as the studs I'd welded into place earlier. That saved me a lot of drilling! The transmission crossmember location ended up a bit off because I'd aligned the rails for the T5 setup, but that was easy enough to cope with.
entry 832 - tags: Drivetrain, v8
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 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 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