27 Oct 2013

My dad passed away peacefully on October 25. If you’re a regular reader you know that this has been a long time coming, so it wasn’t a surprise. Okay, enough of that.

The format editing of the manuscript is nearly done. Next, the front and back cover art must be created. Once that’s done, it’s time to get a few test copies made up for the final review. There is a quote early in the book that has proven to be very true: `Writing a book is an adventure. To begin with, it is a toy and an amusement; then it becomes a mistress, and then it becomes a master, and then a tyrant.” – Winston Churchill. It means by the time you’re done writing and editing the thing, you never want to see it again!

To end on a high note, my videographer buddy compiled a 10-min video of Midlana at the autocross, http://www.youtube.com/watch?v=CJXmuqNGO4s. The video doesn’t seem all that exciting, but for autocross, unless you’re really into it, or inside the car for that matter, it’s hard to get a sense of the dynamics at work. In a couple places you can see where the back end came out and instead of backing off, I kept my foot down to see what would happen. No smoky burnouts or huge lurid slides though, which is promising since it means that there’s nothing terribly wrong with the design. The video might also illustrate one reason why I’m now more into trackday events, but that’s just me.

21 Oct 2013

First things first, Midlana was run at a practice autocross last Saturday, and I’ve been hounded with “So how did it do?” The car did fine; nothing broke, overheated, fried, melted, or shorted out. As I was waiting to go out on the first lap, I realized that it’s been thirty years since I’ve been into this sport since trackdays grabbed my interest. Back then, it took several years to get good at autocross, and of course, nearly all that skill is gone, never mind me being a lot older.

So how did it do? About as expected for a high-powered mid-engine car that, frankly, is a little outside its environment. In low speed steady-state sweepers, there’s a lot of understeer, as expected with 30% weight on the front tires. Of course, how much time does the car spend at a steady speed around a turn? Well, in an autocross, it seems like a lot. Anyway, after a while I started getting back into it, using the fact that trail braking causes weight to be transferred onto the front tires, greatly increasing front grip (just like when driving a kart). Doing so helps both the front tires stick and the rear tires to let loose, starting the car rotating into the turn. Then, off the brakes and onto the gas, using engine power to position the rear as desired.

The good news is that the car isn’t easy to spin (I never did find the oversteer angle that it couldn’t hold). That’s been the biggest question ever since it was designed – what would it do when the back end comes out. Some cars have a nasty habit of sliding the back out, then catching and snapping back the other way faster than the driver can catch it. And, like most mid-engine cars, getting on the gas hard does bring the back end out, but the key is to not let off the gas. Midlana’s rear tires say put or tuck back in – good! Tire wear at the back looked great, I’m not changing a thing. Tire wear at the front, meh; autocross requires a ton of camber and I’m just too lazy to dial in a lot, then take it back out for the street. Right now it has about 0.5 degrees, which is obviously not enough, but for the street it’s fine. For the upcoming trackday event I may add a bit more. The tire pictures below are arranged front left, front right, left rear, and right rear. There is also some in-car video we’re editing but that’ll take some time.

Cars handle much different at trackday events than when on an autocross course. In autocross, it’s all about getting the car to rotate quickly, which means a lot of front camber and a large rear anti-roll bar. Take that same car to a trackday event and it will likely go off the track backwards in a big way. Back when I had the Datsun 1200, the rear bar was completely disconnected for trackday events, which transformed it into a mild-handling car around high-speed turns. What’s nice is that with no bars on Midlana, there was no understeer, which indicated that the native handling of the car is neutral at higher speed, just the way I wanted it. We’ll see if that’s still true on the big oval in a few weeks – though, see below.

In other news, the grammar editing of the manuscript is done! Now, another pass starts; “zooming out” and looking at formatting issues instead of spelling. That’ll go much quicker, and then it’s time for test copies. The final manuscript ended up just over 400 pages, though it may inch up a bit more with the autocross and trackday pictures and comments. As a teaser, the Table of Contents is included below.

And finally, someday within the next several weeks, I’m going to get a call that I know is coming but don’t want to hear, that my father’s passed away. It’s been a long time coming; he’s currently between worlds, simi-comotose, aware that people are around, but that’s about it. It’s not easy looking at him, he who raised me, and realizing that we’re all here just for a while. It’s really driven home the fact that time is ticking and that we have no idea how much we have left, at the same time we think about how we use our time. I can say that it really makes watching TV or YouTube seem like a much bigger waste of time than it used to!

Midlana is signed up for a trackday event in three weeks, but we’ll see what the Universe has in store.

13 Oct 2013

Here are the findings of last week’s fuel pressure failure – educational, and very humbling:
1. Installed new Bosch 044 pump, which is much larger than the Walbro – still zero fuel pressure!
2. Kinked the fuel pressure regulator return line to see if fuel pressure would increase – still zero.
3. Attempted to empty tank by rerouting fuel hose to regulator into a fuel can instead – still no flow.
4. Assumed FOD plugging up tank outlet – wrong, full flow at outlet of tank.
5. Assumed FOD plugging up 40-micro inlet-side fuel filter – wrong, full flow out of inlet filter.
6. Connected outlet of pump directly to fuel can – full flow.
7. Disassembled 10-micro outlet-side fuel filter to examine filter element. Filter element was in good condition, but noticed that flow direction arrow on filter housing was opposite how I had it connected (so what, right?).
8. Examined filter element for signs of deformation – nothing. The only notable difference was that the spare had a flat end (second picture) and my filter had a rounded end (third picture).
9. Installed new filter element, reversed filter plumbing, turned on the pump – full pressure, engine started.
10. Couldn’t figure out how the filter element could prevent the car from starting, since it was neither clogged nor collapsed.
11. Then, it hit me. Running the filter as I had it, fuel entered the filter on the inside of the element (see fourth picture), flowed through it, then down to the other end of the housing, and out. Apparently, the filter element finally developed enough pressure drop for it to be pushed off the end of the inlet housing, hitting the other end of the housing, where fuel pressure deformed the filter element end cap into a perfect plug – and presto, zero fuel flow!

It could have happened anytime, anywhere, and it was a bitter pill that it happened on lap four of a race weekend. My guess is that it was due to the higher than normal fuel flow giving it that extra push; a bitter lesson, that. I don’t know how I managed to install the filter backwards; it must have been during final assembly that I either forgot (or never noticed in the first place) that it was direction-sensitive. So I have to take back all the bad things I said about Walbro pumps; there was apparently nothing wrong with mine.

In other news, I’m pretty sure where the banging noise is coming from. The front engine mount is very close to the chassis, close enough that it is likely hitting it when getting on or off the gas hard.

During assembly of the new fuel lines I experienced something that I’d only read about. After the hose was assembled I blew through it and it seemed to have poor flow. Looked into the end of it and, sure enough, there it was, the infamous “flap.” Very good to catch it now because it could have caused all sorts of odd problems if it closed only under high fuel usage, very likely causing the engine to stumble or run lean.

There’s a local radar trap which hadn’t been active lately, but it was today as I was returning from checking out the new fuel system. I think the only reason I didn’t get “rewarded” was because the cop had just taken a reading on the guy in front of me, and he seemed so surprised to see such an unusual car that he momentarily lowered his radar gun, giving me time to slow down. Close call.

Lastly, progress on the book manuscript is moving right along. The final editing is about half way done, so another couple weeks for that. Then there’ll be one more pass through to check on physical layout of the pages, such as figure placement, dangling paragraphs, and mis-sized pictures. After that, several draft copies will be printed, with a final “fan through” to check for anything really bad, and then it’s time to go live. So for now everything is still on track for a late November release.

7 Oct 2013

“The Fasted Road in the West” – for some people.

The Willow Springs trackday event was this weekend, but unfortunately my fuel pump failed (probably) after four laps. Finding a spare Walbro 255 lpm unit turned out to be impossible; no car parts store, offroad outlet, or Honda go-fast shop had it, so my weekend ended early. Obviously the pump must be used in <em>some</em> cars, I just don’t know which ones. In hindsight I have no one to blame but myself for not bringing a spare pump; I thought that parts stores stocked them, nope. I’m lucky that it was a clean failure instead a slow decrease in pressure, as that’s seriously bad news for a turbo engine. The pump still ran but sounded odd, and there was zero fuel pressure, so it seemed to be the pump. That aside, I learned that:

1. The car is fast as hell, 132 mph down the front straight (GPS speed, so it’s accurate), and that was just getting started. I can almost hear Walter White saying, “*I* am the one who passes!”
2. Never did find the braking or cornering limit. The hotter the brakes and tires got the better it worked.
3. The small amount of tire wear was very even.
4. Probably the best news is that drop-throttle testing showed no oversteer, the biggest concern of the suspension design and rear weight bias. Of course, since the car never reached the limit of adhesion, it’s hard to know how much margin I had.

A Bosch “044” pump is on order. A reader said that he suspects that the Walbro died due to sucking air. I can’t completely discount that theory because I don’t know for sure what happened, but why was it able to last 1000 miles of street driving but only four laps on-track? The tank has a built in accumulator to which fuel is returned from the fuel rail. The tank was nearly full, about a 10″ head on the pump. The tank has a lot of baffling along with one-way mouse doors all leading to the accumulator. So while I don’t know for sure what killed fuel flow, it’s hard to blame air.

The Web rumors about the Walbro pump not being reliable “seemed” true and the initial thought was, “once asked to provide real flow it just couldn’t.” However, after thinking it through it seems unlikely. I think that the pump <em>always</em> provides full flow and the fuel pressure regulator decides how much to choke off the return line in order to provide a given pressure. Curious about how the pump failed, it was disassembled and to be honest I was impressed with its quality. Everything looked fine other than some discoloration on one set of commutators, though resistance of the motor was constant regardless of position. The rotor wiring was not broken or burnt, the gear pump components looked fine, and the one-way valve on the outlet was functional as well. This has me a bit worried; maybe the problem is somewhere else, but where? A failed fuel pressure regulator? It read zero psi with the pump on and the engine obviously wasn’t getting fuel, so maybe it was passing 100% of the fuel back to the tank, which might result in no indicated pressure? Or, could there be a huge blob of aviation fuel tank sealant used during construction that broke free and plugged up either the outlet port or the inlet fuel filter? Of course, playing devil’s advocate, maybe that blob of tank sealant just floated away from the outlet port and will return on a future date. It could also be that one of the one-way fuel doors broke off and ended up against the fuel exit port, though that seems less likely. The engine quit under braking going into Turn 3, so if the door broke loose I’d expect it to slide forward, away from the pickup.

Oh well, what’s done is done and a Bosch 044 pump (which is claimed to be far more reliable) has been ordered. While replacing it, the inlet fuel filter will be examined for massive clogging (though it’s hard to believe that it could instantly plug up like that). The Bosch will be plumbed in and we’ll see if fuel pressure returns, and if so, great.  It should be in and running next weekend and we’ll see what’s what.

As for the cars that showed up, there were Miatas, Porsches, Corvettes, a few Alphas, BMWs, five original Mustang GT350s, and a supposedly authentic aluminum-bodied Cobra. The Mustangs sounded like they were going about 180 mph, getting about a 1:35 lap time. The Cobra was slightly faster with a 1:33, but the big surprised was the 10-yr old BMW M3 and its 1:32! Very impressive. I didn’t bother timing myself (thinking there was plenty of time for that later) and didn’t even start the GoPro, figuring I’d recorder the later faster laps. Uh huh.

Lastly, on Saturday night we were up late taking time exposure shots of the car (more on that later) and a desert fox came walking by—no kidding. It looked like a small dog with a huge bushy tail. I suspect he lived somewhere near the track and survived off leftovers he found in the trash cans. Anyway, he came to within 10-15 feet of us and just sat down! I started to reach for the camera and he ran off. That would have made a cool picture. Anyway, there’s another track event in about a month at California Speedway. That’s about the latest possible timeframe for getting observations into the book. The only downside, if you can call it that, is that the track is very fast, not really what I wanted for an initial handling checkout. Of course, no one says that I have to go 150 mph through the fast bits.