22 Mar 2008

Checked out my brother’s nearly-completed Super Stalker. All that’s needed is paint, installing the fenders and painting the engine cover. He’s been driving it a few weeks now so first he took me for a ride, then let me drive, then I let him drive Kimini.

Driving observations:
His car has TONS of low-end power thanks to the supercharger, the problem is getting it to the ground. The long wheelbase and steering rack results in a rate about half of mine, and I may have the same issue with Midlana. A slower ratio is better for the street, though I’m curious what he’ll think about it on-track. Probably the biggest difference though is ride quality. He went on a road that has two bumps in it, one upward and another downward. His seats have less padding than mine, but when we hit those bumps, it was a real harsh blow to the backside, enough to make you clamp your teeth together when approaching it. The wind whipping around the windshield wasn’t as bad as I had previously experienced in a Caterham. He said that’s probably because he made the windshield both 2″ wider and taller. The exhaust sound is pretty loud, obviously due to its proximity to our ears, but made worse by the low frequency nature of the V6. At a certain speed and engine load, it all resonates, like someone feeding 100Hz into your headphones and cranking the volume way up. He said it’s loud even with earplugs because they don’t filter out low frequencies well. He may try pointing the exhaust tips differently to see what happens. Oh, and now that I’ve driven both a high and low-pivot pedal setup, I’m not concerned about the differences. Yes, the brake pedal arc does lift your shoe off the floor, but it simply isn’t a big deal. After a couple minutes I didn’t even notice the difference.

His observations of Kimini were that it was much more refined, much quieter, and that the steering was much more sensitive. When he drove over the same two bumps he couldn’t believe the difference. That’s the day-to-day consequence of high unsprung weight and little suspension travel. Examining the rear suspension showed that it has only about 1.5″ of compression travel so he may try relocating the shocks to free up some travel (allowing softer springs and shocks.) He’s also looking into stiffening the shocks and swapping in stiffer springs.

No we didn’t drag-race. We both agreed that the two cars are very different animals and we both respect the other’s car enough that there’s nothing to prove – each has its strengths. I think his is faster in a straight line, but only if he can get the power down. In the curves, who knows. There’s no way to properly compare the two outside of a racetrace. Having driven his car, I can’t understand why anyone would want more power. First and second are useless if you hammer it, and third is a dicey proposition if it’s not pointed straight or if the road’s not smooth. All more power does is make more smoke, so he’s getting wider and stickier tires to help cure that.

13 Mar 2008

The network problem was an intermittent router, which was a real pain to figure out. A number of times I tried bypassing it to see if it was the problem, but it had apparently already messed with the computers, so it appeared that the modem was bad, or that the problem was with the ISP. Anyhow, a new router fixed everything, and it’s all running much faster than ever before. I think the old SMC router was going bad over a long period of time. Linksys stuff rocks, plug it in, turn it on, and it just works, no drivers, no settings to mess  with – nice.

Alright, back to suspension design.

5 Mar 2008

The readers have spoken; the front suspension shall be push-rod. I won’t know how the rear suspension will lay out until I get to that part of the design. I suspect it’ll have to be push-rod, too, due to the deep wheels. Even though most builders will use narrower wheels than what I’m using, I have to design it to work with the widest wheels that the design will accommodate.

Ordered a set of fenders from www.kineticvehicles.com which are needed during mockup of the rear part of the chassis, nevermind that I’ll need them eventually anyway.

Oh, and it looks like I found a buyer for… no, not the car, but the molds. They would have gone with the car, but the lack of car offers meant I was happy to find a buyer for them. It’s just as well; had they left with the car, they would have essentially been given away for free.

4 Mar 2008

After thinking it over and hearing from readers I’ve decided to stick with Miata rear uprights. As several people pointed out, I’m supposed to be designing an easy-to-build, simple car, not something where all sorts of different donor parts are needed and custom parts fabricated. Okay, lesson learned.

Speaking of features on the car, I have a reader question: Do you want push-rod suspension or traditional outboard suspension? Push-rod suspension: looks sexy, good stock travel. Cons: heavier, more complicated, takes up space inside the chassis, takes longer to build, more expensive. Outboard suspension: simple to build, easy, cheap. Cons: not great shock travel. Your choice, pick your poison!

My brother just started driving his Super Stalker, even though it’s not complete (hood’s not painted, no fenders or mirrors, etc). He said, “First gear is useless… second gear is useless, third gear is, oh crap!” I guess he’s impressed.

3 Mar 2008

Forgot to mention that I took Kimini up to the “Cars and Coffee” event. This has turned into a huge deal, with hundreds of cars and spectators. Nearly everyone’s there by 7am and gone by 9am(!) which is cool because it leaves you with practically the entire day for other things. As cars start leaving, a crowd gathers at the exit, cameras in hand, to watch and listen as some exotic machinery leaves. In fact, there was a Ferrari 250GT there, or something that was so close to an original it had people all excited. Anyhow, I don’t post pictures any more because there are 100s of people who do so now. All you have to do is Google “Car and Coffee 3/1/08”.

In other news, I’m closing in on the front wheel geometry. Because I’m making the front track wider than the usual Locost, it presents the opportunity to use an unmodified Miata steering rack. People have a lot of trepidation about modifying steering racks, so this both simplifies and speeds up construction. Moving links around and juggling the wheelbase made it all work out, so unless something nasty shows up, this iteration looks promising.

The second set of rear uprights arrived, setting a new record in poor packing. Styrofoam peanuts don’t protect 40lbs suspension parts, so they punched a hole in the box, which arrived half empty of peanuts, I’m sure UPS appreciated that. I’d be upset if they were broken, but thankfully suspension uprights are darn tough. So, portions of these may be used instead of the Miata rear uprights. As much as I look at the Miata parts I just can’t figure out how to make a clean, easily adjustable rear suspension with them. While the alternative design requires fabricating custom uprights, the bolt-on spindles don’t require making precision bearing cups. (This adheres to my goal of making the car producible without requiring a lathe.) I’m curious what people think though, about making suspension uprights if it is an improvement over using the stock Mazda parts. Of course the question becomes, “How much better would it be? Is it worth the extra work?” I hope to answer that soon. It’s the eternal compromise, do I use parts which are just “okay”, or require extra work to make it much better? It’s a thin line between doing it right and getting it done.

25 Feb 2008

Bought the domain midlana.com, the future site for Midlana builders. Granted it’s early but I didn’t want to find the domain gone if I wait. Looking into various forum software packages, I’m not sure what I’m signing up for, probably hours of removing spam for enlargement devices, Nigerian bank offers, and on-line pharmacies, lol.

The garage is filling up, with few nibbles but no offers on Kimini. I realize it could be a long time before finding a buyer; I need to get off my butt and start advertising more seriously. I figured I’d post it here first to give longtime readers first shot at it, but all it proves is that the Internet will beat a path to your door – as long as everything’s free. So I’m going to start showing it at the “Cars and Coffee” event in Irvine, CA, where some very expensive hardware show up, along with some rather wealthy car nuts. That venue should be good for finding buyers.

A buddy said I should have held off buying an engine (which will always be the case.) He said the one to have “today” is a direct-injection turbo engine. The big advantage is that there’s no detonation (no fuel in the combustion chamber until needed), so a turbo 10-11:1 engine has very little lag. Oh well, there’s always something better that’ll come along. Eh, I’m fine with what I’m doing, and like I said, there’s always a better engine next year.

I’m reminded that I’m leaving out project details again. It’s not on purpose, I simply forget to include them. The suspension uprights are Miata all around. While they’re not perfect, the reality is that they’re widely available and affordable. Going through the design process with Kimini taught me how make things easy to build. While Kimini has excellent suspension geometry, it’s because the front uprights were heavily modified and the rears fully-custom fabricated. That’s fine if you don’t mind spending weeks and weeks making them, including using a lathe to fabricate bearing cups to an accuracy of 0.0001″. However…

That said, I’m not sure I like the Miata rear uprights. Even as I work through the front suspension, I’m eyeing them with more of a glare than satisfaction, especially the top mount. In the Kimini book I note how some builders used bolt-on rear spindles – and how much easier that is than making bearing cups. In fact the latest Locost book specifies fabricating rear uprights using bolt-on Ford Sierra hubs. I’d use something domestic, but I’m torn between making the car fast and easy to build and slightly slower to build but having better rear geometry. Of course the question becomes, “How much better would it be?” I’m certain enough of my, um, uncertainty about the Miata parts that I’ve already ordered a different pair of rear hubs that bolt on. This allows making a fully-custom upright with the pick-ups where I want, unlike the Miata parts that force the issue. It’s too early to tell which path will be taken, and so you see some of the endless behind-the-scenes dithering going on. Again, whichever uprights don’t work out, back to Ebay they go.

20 Feb 2008

More goodies. The nose is from Kinetic Vehicles and is their “catfish nose”. Since I don’t have an engine up front I want to run a low profile nose and here it is. The styling is, as I was warned, going to be tricky, since Locosts are narrow vehicles. I’ve made things hard on myself because I’ve pushed the passenger compartment foward. This means the body taper is going to be tough to match up with the taper of the nose cone. The question is, can I make it work or is it going to look bad? Of course the nose can be widened, but the goal is to try to use it as-is. That way I – and other builders – don’t have to mess with composite at all. That said, I suspect it’s going to have to be widened anyway, but we’ll see. If a decent number of people decide to build the car, I’m sure Jack at Kinetic will be willing to build a wider mold, 😉 Designing the suspension around the nose is a bad idea, as compromising proper wheel control to work with the nose imposes a lifelong handicap on the suspension. So, now starts the endless interations to settle on a workable wheel track.

I have some ideas about how the chassis sides will be styled and I think it’ll look pretty sweet – clean, functional, yet bold, if I do say so myself. Of course people may look at it and think, “Ewww”, so we’ll see, lol.

Also received a K20A2 oil pump and pan, necessary as part of converting the K24A1 engine to the high performance version. The transmission should arrive next Monday.

The last picture is my bestest buddy, Cooper, who likes to rest his heavy head on my knee, tug-of-war rope in mouth, all ready to play. He’ll sit there for quite a while, figuring – correctly – that I’m well aware of the message he’s sending.

18 Feb 2008

It’s here… a Honda 2.4 liter K24A1 and a K24A2 cylinder head! The engine will come apart, in preparation of getting oil squirters added and honing the cylinders for the new rings (and pistons). Compression will be lowered to 8.5-9.0, for running boost on our crummy 91 octane gas here in California. While lots of people say I don’t need to lower compression, I have a good buddy that built all sorts of crazy Honda engines, all the way up to 1200hp drag racing monsters. He said that all it takes is one long hill and being in the wrong gear to cause detonation (pinging) which will very quickly destroy the engine. The plan is to design every part of the engine for 400hp, but run it at a more “reasonable” 300hp.

A little more infomation about oil squirters, these are oil nozzles mounted in the block that squirt oil up at the bottom of the pistons. The idea is to keep the pistons cool to avoid detonation, yet there’s a lively debate on the forums regarding the need for them. Some people say that switching to forged pistons negates any need for them, while other’s say anything that keeps the pistons cool is a good idea, which I agree with. Factory stock pistons are cast aluminum. This means that as the engine gets hot, the coefficient of expansion for both the piston and cast aluminum block is similiar, so as the piston gets hot the piston-to-cylinder clearance is maintained.

In a boosted engine though it’s common to swap in forged pistons which are far stronger and more resistant to detonation. However, since they are made different, their coefficient of expansion is higher than cast pistons. This can be a very, very bad thing if the engine is run hard (like up a long hill or on a road racing track). The piston keeps getting hotter and hotter and expands faster than the block. Eventually it expands enough to start rubbing on the cylinder walls and once that happens, they get really hot and completely lock up the engine. Sooooo, oil squirters seem like a very good idea to me!

I’m not sure when the engine build will happen, probably in parallel with the chassis build. The goal is to have it done before the chassis is finished. In fact, I’d like to have it done before it’s time to put it on the chassis table, but that’s probably optimistic.

16 Feb 2008

Returned the brake rotors – they’re just too heavy – backing off to “regular” brakes instead of the vented Sport discs. The weight made me give up whatever additional cooling capacity they have. The solid rears are roughly half the weight of the 12lbs vented units. If there’s any heat issues, cooling ducts can be added, upgrade the pads, or go to vented rotors as a last resort.

10 Feb 2008

Found an engine; it’s paid for and will be here in a week or so. Found a transaxle, too.

The brake discs are VERY heavy, 13lbs each for the fronts and 12lbs for the rears. This is due to going with larger vented rotors than solid discs. I had been assured that small solid disc brakes will be fine… so I may take these boat anchors back.

I saved the bombshell for last though it probably won’t be a big surprise to regular readers… I’m going to be selling Kimini.

1 Feb 2008

Ordered the nosecone and brake rotors so that front suspension design can progress. The nosecone is for determining where the inboard front suspension pivots go. The brake discs are for measuring the thickness at the mounting face, as it shifts the wheel center outward. I feel better measuring them – and every other component – myself. The seats will probably be next.

I got a great deal on a Tilton hanging pedal set, but after seeing how compact, low, and light my brother’s floor-mount pedals are, I wonder if I should go that way. Than again, when I tried them I experienced what other people have said about floor-mounted pedals. The arc of the pedal and foot don’t match, lifting my foot off the floor. Not terrible, but something that would take some getting used to. I have to think about it.

25 Jan 2008

Finally tested the coil-over shocks with a proper press and load cell. As suspected, there’s a sizable gas preload pressure before the shock starts to compress. It was a lot of fun, actually, as I rarely have the proper tools to do this. I’m always having to guess or approximate what I’m doing due to not having the right tools, always making me feel bad about doing a half-assed design job. However, when I’ve got the proper tools it’s a really good feeling knowing that the data I’m collecting isn’t “roughly” this, or “about” that – it’s exact. With this data I can confidently design the push-rod suspension, and know it’ll work first time. That’s a great feeling to have even before it’s built.

After 25 years of resisting, I’ve finally given into probably having two sets of wheels and tires, one for the street and one for the track. Given that, I’ve backed off on buying the lightest street wheels possible, since they’ll have to deal with potholes (and bonehead tire installation shops…) Street wheels are far from light but then again they cost less than 1/3 that of a really light racing wheel. So it was a bit surprising to come to terms with purposely buying something that isn’t the best. Yup, today, street wheels were ordered. Theoretically they aren’t needed but they’re invaluable for suspension mock ups and checking clearances. Having CAD is pointless when detailed dimensions aren’t available, which is a lot of the time. Wheels are especially bad in this respect, and it’s a rare manufacturer that supplies accurate cross-sectional drawings. The best anyone gets is bolt pattern and back-spacing.

The ultralight track wheels that cost crazy money will come later after the car’s built and ready for the track.

18 Jan 2008

Regarding the bike shock, the spring rate is around 500lbs/inch. The problem is that it’s preloaded, and the high-pressure nitrogen adds to the overall rate. This gives a discontinuity, where nothing happens for several hundred pounds until it finally starts to compress. Until I plot points at higher force I won’t know what I have. This weekend I’ll make brackets to properly support it and run a force vs. compression test on Monday. Oh, and another impressive feature of the shock is the mount bushings. I pulled a bushing out and there are needle roller bearings inside – very cool! My expensive Konis don’t have that!

While a great value, I can see a potential problem using these shocks, which is a shock travel versus spring rate issue. That is, I can trade one for the other, which is fine if one’s not important. Unfortunately there’s a squared term in the installation ratio which makes things more interesting. Instead of getting all wound up over this I’ll remain calm until I get it all into the suspension design software to figure it out. Worst case I have to use different units at the back, or swap springs, which isn’t so bad. That’s part of the beauty of buying off Ebay. If you buy used stuff and end up not needing it, you can sell it for virtually the same as what you paid.

Several Locost builders I know have used these shocks so I know they can work. Of course most are using sportbike engines so the very low weight translates to lots of suspension travel. I’m going with a heavier but more “polite” street engine which will eat into the little shock travel that’s there. Guess I’ll be the first to know if it works or not.

On the tire front, I’m going to try to decide tire diameters this weekend.

13 Jan 2008

Tires:

Tires are the most important – and most frustrating – decision during new car design. Nearly every suspension design parameter is related in some way to tire choice. I’m owing to stay away from hard-to-find 13″ street tires so it means going larger, to 15″ if not 16″ or even 17″. I’ve spent weeks going back and forth between brands, trying to settle on a size that everyone will be able to find, both now and over the life of the book. This very likely means going to 16″ or 17″ to guarantee some non-obsolescence. Yes, larger wheels and tires have a higher polar moment of inertia, weigh more, and cost more. On the other hand is the possibility of simply not being able to find what I specify, so the former outweighs the latter.

Before people jump up and down saying that it’s easy to find 13″ and 15″ tires, well yes, and no. Sure they’re out there, and they’ll continue to be for some years; the problem is the compounds. For as light a car as is being designed, high mileage tires are neither needed nor desired. This thing’s not going to driven in snow or rain (much) so all-weather tires aren’t wanted (besides, it’s a sports car). We need what tirerack.com calls “Ultra Performance Summer Tires”. This greatly cuts down the list of contenders, and even the list of high performance 15″ tires is getting thin, about how it was with 13″ tires when I designed Kimini. Note that this only applies to street tires, NOT race tires. For the track, getting 13″ and 15″ tires is easy, yet that’s not the starting point of this project – it’s going to be street-legal. 14″ tires aren’t mentioned because they never were a popular size and are fading fast, there’s no reason to even go there.

So in an effort to design in some staying power, the tires may be larger. For the moment, my sole concentration is on choosing tire diameter, a primary design concern. At this point, whether the tire’s made for 13″, or 15 – 17″ wheels is immaterial. However, when I read tire data and see that there’s a grand total of only one or two 15″ sizes, the writing’s on the wall.

11 Jan 2008

I realize I haven’t described what Midlana looks like. While the details are still squishy, it’s basically a Lotus Super Seven with the passenger compartment pushed forward enough to allow a transverse drivetrain behind the driver. It’s not original (what is?) as there’s one manufacturer in England (Sylva) that produces one now, the Riot. Will Midlana be a knockoff of that, no, though all these cars are a knockoff of something. No, it’ll be its own thing, but will use commonly available composite so the builder has little or no messy, stinky composite work to do. It’s going to be “buildable”, easy to maintain, and inexpensive.

Thanks for all the comments regarding seat placement, sorry I couldn’t respond to everyone separately. I think I’m going to stick to the traditional side-by-side placement. It’s a combination of reasons: routing the seatbelts, not getting undue attention from safety inspectors, motor vehicle registration people, and later, cops, and, being able to hear, say, a driving instructor. From a selfish point of view, it’ll be much easier to get it through registration in California if it looks like a “normal” car. Then there’s the “too different” aspect; I’d like this car to be something people <i>want</i> to build, and the center seating might be a bit much. I know I’ll never make everyone happy, but alienating a huge group right off the bat’s probably not a good idea!

Engine choice: The builder will have a decent-sized bay to install whatever they want (with limits). Everyone has access to different engines due to differing budgets and regional availability. Then there’s form factor. There are many transverse FWD drivetrains out there, all with similar layout; that’s the type that Midlana will accept. Of course there are other engines like the Subaru flat-four: low, light, with a “real” transaxle. The problem is that the transmission tail shaft sticks out quite far past the axle centerline. That’s of no consequence if the car’s designed for it, but it’s not. A transverse layout is shorter, front to back, which packages much nicer, and there’s the rub. There are far more transverse drivetrains out there than Subaru drivetrains, so I didn’t want to force builders to use only one engine brand. (Technically the engine bay could be made large enough to fit everything on earth, that it gets out of hand. This is the consequence of following a cookbook; you’re stuck with the designer’s vision).

10 Jan 2008

I have a question for you: if you had a choice of building a car with two seats side-by-side, or two seats, one behind the other, which would you choose? In the first case, the car could be considered more “sociable”, in that you can easily talk to and see each other. This is important, but I’m not sure how much. I mean, how many people do you Really give rides to? Does your spouse Really love riding in the car, or is it more to be polite and put up with your crazy hobby.

Or, do you compromise the social aspect of it by putting yourself front and center, like driving a “real” race car. Also, the car wouldn’t have to be all that much longer since the rear passenger’s feet could straddle the front driver’s seat. There’s no pesky driveshaft tunnel to fool with, so that’s not an issue. Hmmm, something to think about, but I’d like comments either way. I think I know the answer, that it’s just a bit too “different”, but I’d like you to consider what you get (as a driving experience) before discarding the idea).

It suddenly hit me today that unlike Kimini, where I did anything I wanted and didn’t care what anyone said, now I have to care what people think. It’ll take some readjustment, having to listen to what people want! Or do I say, “This is how it is, take it or leave it.” That doesn’t do well to sell books with that kind of attitude.

Let me know. Of course, none of this is going to happen unless I find a drivetrain.

9 Jan 2008

Just this morning I was very, very close to getting a great deal on pistons and rods for my chosen engine. Then, I started thinking about it all and canceled the deal, but let me back up and explain. I preface this with, once again I’m going mid-engine.

My brother, who’s using the GM supercharged 3.8l V6 in his Stalker, of course thinks that it’s the no-brainer obvious choice. I said there aren’t decent transaxles for it, and adapting one to it seemed silly, but he said with enough effort I could make it work. Exactly… I don’t want to reinvent the wheel when there are already FWD drivetrains waiting to be used, and not really heavy one’s either. I’m comfortable with Honda engines, having built Kimini using a Honda H22A1. Because of the awesome aftermarket support, both in parts and forums, I’ve decided to stick with them.

So over the last six months I’ve been thinking about which drivetrain I’d like use. While Midlana will accept many drivetrains, I still had to pick mine. Naturally I was drawn to the largest 4-cyl that Honda makes, the K24 (2.4l). There are four variations, going in the CRV, Acura TSX, Euro Accord, and USDM Accord. Each has different power levels, with the TSX being the highest, Unfortunately for that very reason, it’s the most desirable and sought after. On the other hand, the Accord, making about 20% less power, is typically about three times cheaper – really. Many people convert these over by adding a better head, changing the pistons, rods, and so on. It wasn’t until today that I started rethinking my whole engine selection. If I get the Accord engine, I’ll have to build the engine before I can use it; that wasn’t the intent at all, I want to drive the car as soon as it’s on its wheels. Then I started adding up the costs of getting a Accord engine to what I want and was surprised that, for the money, I could just go straight to a 200hp TSX engine. It’s a slam-dunk solution; buy it, put it in, and I’m all set. Even better is that when I go forced-induction, zero internal modifications are needed. [that’s what I thought at the time, hah (Sept 2016)]

Of course, don’t expect what I say today to be what I do tomorrow, as I’m full of vague nebulous ideas that come and go all the time. Just because I come up with something doesn’t mean it’s going to stick around, and it can be discarded like yesterday’s Hollywood starlet. On the other hand, I realize people like reading along, following my thought process, be it smart or completely idiotic. Anyway, the more time I spend typing the less I have to work on the design, so I’m off to work on that. I’ll discuss the plan in more detail in future entries.

8 Jan 2008

A kind coworker let me take dimensions off her car’s drivetrain, the make I’m considering using as donor. This is an important step because, even though many engines will fit Midlana, I want to make absolutely sure that mine will fit, too.

6 Jan 2008

Well, vacation has come to an end, though I managed to cross some things off the to-do list: clean the garage, make good progress learning CAD, and added pages to the book manuscript. Also received the suspension design software from Wm. C. Mitchell, along with an amazing suspension book by Rowley, so between these two I’m ready to rock and roll.

Oh yeah, I wore out the little electric RC helicopter, surprisingly, not by crashing it; the tiny plastic gears finally stripped out. So of course I fixed that by buying a bigger helicopter 😉

Looks like, as with Kimini, I’m going to have to buy a drivetrain if I want to know how big it is because no one’s taking the time to help me measure certain drivetrain dimensions. A little disappointing, but as expected. Short of that, I realized that a coworker has one of these cars so I guess I’ll be measuring her… engine.

2 Jan 2008

Got an electric helicopter for Christmas, which is surprisingly capable for the low price. Great fun flying indoors, as long as Cooper doesn’t get at it. From his point of view, it’s a big bug that invading his space!

Spent the day cleaning out the garage, and it’s far more pleasant now,  not stepping on boxes and stepping in grit everywhere. Of course our  trash can now weighs about 250lbs… I wonder if the trash guys will  complain. A clean garage is a vacuum, wanting to be filled with something. I’m working on that.