Tag Archives: grass pollen

Still trying to get stuff done and not succeeding

Weather and sleep schedules are interfering with actually doing things in a timely manner. I staggered around until about 1130 before collapsing and eventually shutting down completely about 1230 or 1300. I woke up enough to check the time about 1900 and finally got out of bed in time to catch Biden’s speech about 2100. Pollens are still interfering with my sleep, making getting shut down to sleep hard, and then making it hard to get fully awake with working eyeballs.

Still trying to figure out the engine situation for the Sprint-T. I mean what I want is maximum torque for getting out of the single-pylon turn, which implies a mild cam, long intake runners, and hopefully a lot of displacement. Or maybe (also) small turbos that light up more quickly than big turbos and a small displacement engine. I’m looking for either a large displacement engine or a good turbo manifold. Also VVT. Changing timing can drastically change the points of opening and closing of the intake valve and move the torque band from lower to higher RPM. That will be fun, but not earth shattering. Basically VVT extends the powerband a tiny bit and makes the long runner intake work over a wider RPM range. Dangit, I know what I’m trying to say, but I’m having a terrible time trying to get my ducks in a row to say what I mean.

Basically VVT widens the powerband a scosh compared to fixed valve timing, but it doesn’t work miracles. There are some Engine Masters videos on the subject but if you aren’t a subscriber you can’t view them. I did link some YouTube videos earlier that explain the benefits of moving the cam timing, well VVT lets you do that while the engine is running, about 40 degrees for the late model Gen IV or about 50 degrees for the early versions. Naturally you have to check piston to valve interference at the extremes of adjustment to make sure you don’t get the pistons hitting the valves because the VVT changes the valve lift at the point the valves get closest to the pistons, and for some cams the valves will actually contact the pistons unless the swing on timing is reduced. Or move the swing away from the interference, which is a thing also. Like I wrote earlier it’s something that needs to be explored more thoroughly, probably by someone with more resources than me. The best that I can do is get the biggest VVT cam I can find and pair it with the longest intake runners I can find and then swing the timing to see what performance benefits I can find. I’m hypothesizing that running VVT advance at part-throttle cruise could generate better mileage, and if I see evidence of that in the VVT map I’ll have verification of that hypothesis. But on the other hand if I don’t it doesn’t mean it’s not true, just that it isn’t programmed into the ECU, probably because there wasn’t enough benefit to justify programming it into the system.

OK the sun is up now, time to “make the doughnuts” and if you get that reference you are either old or you like really old commercials.

Not feeling good today

I did several days in a row with 2-3 miles walked with allergies and now my back is complaining, not loudly, but making its presence known. This is my notice to take a break and not overdo things. Also after several days of good behavior the “m” key on the keyboard is acting cranky again, and Google keeps sending me notices that my OS is no longer supported.

Now this can be dealt with in many ways. I can buy a new computer (ha, ha), I can get the keyboard fixed and install Linux, I can install Linux on my Dad’s old computer after I drag it out of the box it has been stuck in since 2012. And one of my friends might have an old laptop they can give me. First I need to call and find out how much getting the keyboard fixed will cost, then work from there.

On the Sprint-T I have been contemplating a frame revision that would add maybe 40 pounds but provide a major increase in torsional stiffness. It isn’t as pretty now, but it will be much more tunable for handling. Basically what I did was make sure all the possible load paths were continuous and triangulated in all 3 dimensions and clear the body. It was that last requirement that has been the monkey wrench in the works, as the body is 34″ wide underneath and 45″ wide at the top and there has to be a structural member to meet the mounts underneath or the body would have not crashworthiness. That’s not the problem by itself, the problem is the diagonal from the top of the rear roll hoop to the bottom of the front roll hoop. Now I thought I had this solved a while back, but when I traced the load paths I found it went all wonky at the front roll hoop. The loads went from in line to bending around the front hoop because of having to have a member under the body and the diagonal snake around the bowed-out sides because there is no straight line from the top of the rear hoop to the bottom of the rear hoop. Interestingly enough, there is straight line access from the top of the rear hoop to the middle of the front hoop, and back to the bottom of the rear hoop, but that places bending loads on the front hoop unless there is a corresponding member from the front suspension support to the front hoop. And that is what increases the weight so much, about 8 additional members about 50″ long each weigh 30 pounds total plus the gussets at each intersection add about 8-9 ounces each end. If I could reduce the size of the structural members any more without worry about damage from people leaning or climbing on the car I could make it lighter, but I have to use the frame as a ladder to get in through the top of the cage.

While I have been writing about fixing the mistakes in my frame I had a show about engineering mistakes and fixing them on the Science Channel on the Tee Vee. Some of those mistakes cost hundreds of millions of dollars to fix, some couldn’t be fixed for any amount of money. I’m just glad I’m finding my mistakes before I spend money building unusable junk.