31 Aug 2016

Ordered thin fiberglass sheet, foam, epoxy and flox. Building the foam form is the fun part; getting it ready for paint so that it doesn’t look like crap is where all the time (and complaining) comes in.

A few people have asked why an air-to-water intercooler isn’t used instead of ducting. First, what it is: an air-to-water intercooler setup consists of a water-enclosed intercooler, reservoir, pump, hoses, and a front-mounted radiator. Heat absorbed by the water is pumped to the front of the car where it’s dissipated by a separate radiator.

So why aren’t I using one? For the street or drag racing it works fine because the engine isn’t under boost very long. At a trackday or hill-climb however, it can be challenged to shed heat faster than it’s generated, resulting in high water temperature –  heat-soak – and then there’s how to get rid of all that heat once it’s in the system. Other negatives include increased complexity, cost, weight, reduces cooling of the regular radiator, and adds the potential for more leaks. While the air ducting is a project, it’s far simpler in the long run and can be run at speed for an unlimited time.

In unrelated news I ordered two new windscreens, a replacement and a spare. Several years ago I was on a group drive on mountain roads where it had rained the night before. The car in front kicked up a lot of sand and left my windscreen slightly sand-blasted. Every time I drive the car it bugs me, so that’s another thing on the to-do list. Lastly, the polyurethane showed up and the rear mount changed once again. Haven’t driven it but it’ll be better than the Delrin version.

Here’s the record-breaking run of the 1000 hp Nissan GTR at the 2016 Virginia City Hill Climb: https://www.youtube.com/watch?v=L9YMuQWVLL8

29 Aug 2016

First off, my brother did very well, placing third out of approximately 50 cars with a time of 3:22; the only car that beat him was that 1000 hp Nissan GTR and a McLaren 675LT. He took his GoPro 3 to record his run and not very surprisingly, it screwed him over by refusing to power up even on a full charge. He said he’s completely fed up with GoPros and I can’t say I blame him.

Someone asked why a turbocharged car retains more power at altitude than a normally-aspirated car:

As altitude increases, two things changed in favor of a turbocharged engine. First, lower air density means that the compressor has less load, so it naturally increases speed until it reaches a new equilibrium. Second, there’s also less exhaust back pressure (less pressure the exhaust has to push against in order to exit the exhaust pipe), so the turbine sees a larger pressure differential and spins faster as well. Both factors cause the turbo to adjust itself to a higher speed that self-compensates to the higher altitude. It’s not perfect though because the turbo is now compressing air at a lower pressure to a larger factor (a larger pressure ratio). Compressing the air more raises the temperature and in addition, the intercooler has less cooling air flowing across it, so the air entering the engine is warmer than it would have been at lower altitude. Even so, the end result is that a 400-hp turbo engine (measured at sea level) will still make about 370 hp at 6000 feet (without active control to make more), while an equivalent normally-aspirated engine will make about 330 hp.

There is however a negative aspect of turbocharged engines that can even the playing field: heat-soak, where the intercooler can’t keep up and the air entering the engine gets so hot that the ECU must back off on boost. This is a fairly common issue for lower and mid-market turbo cars, where they simply can’t stay at full boost for longer than perhaps 10 seconds. Most of the time that’s perfectly fine, but put that car on a 3-4 minute hillclimb and whatever power the manufacturer promised likely isn’t there at the top of the hill.

In other news, regarding the intercooler ducting and it possibly becoming part of a roof, I didn’t realize how much I use the roll cage when getting in and out. Getting in without the cage’s help isn’t bad, but getting out is, well, entertaining to onlookers; I’ll have to try some other techniques to see if it’s just a matter of a different habit or if it’s a real issue. I haven’t firmly decided which way to go for the ducting, but the list is getting short. The sightline looking into the rearview mirror passes about 1.5″ above the intercooler, so regardless how the ductwork routes, it’s going to block some portion of the view. The difference between the approaches is how much it blocks. It turns out that having inlets at the top corners of the main hoop are even worse because they’ll completely block the blind spots, arguably more important that the view directly behind. Of course it could be argued that that’s what side mirrors are for, which I don’t have. It’s a fair point; I just want to see how much visibility I can retain with some thought rather than chucking it all out the window right at the start of this. If side mirrors become a necessity, so be it.

A derivation of the above is having the inlets at the upper corners turn the air sharply inward, combining together above and just forward of the intercooler before turning downward. I’ll have to mock it up but already think it’s more work than just having the inlet above the windscreen.

Another suggestion was having scoops down low on the sides of the chassis; it’s what “real” mid-engine cars use, but due to Midlana resembling a Seven, there isn’t room between the engine and main roll hope for large ducts to pass through. Even if it could, then what? It would have to raise up out of the engine compartment to feed air into the intercooler from above. Of course, another approach would be feeding that same air into the bottom of the intercooler and assume there’s sufficiently low pressure above to allow it to flow out. Since there’s no room for ducting however, this approach can’t happen.

Lastly, there’s picking up air from under the car – again, there simply isn’t enough room for large ducts to pass air up past the engine.

 

28 Aug 2016

Though the results aren’t announced yet (this evening), my brother’s pretty happy with how the hill climb went, though he did mention that a 1000-hp Nissan GTR set a new all-time record. That’s tough competition since the event is held at about 6000 feet, so his LS3 was making about 353 hp instead of 430 hp while the GTR’s turbo engine retains more of its power. Still, the GTR’s near-4000 lb weight is an issue at any altitude and compensates with computers and 4WD as best it can. He also mentioned that it was on Hoosier tires which was yet another advantage. Since he was a participant he didn’t have time to take a lot of pictures but here’s what he sent (on Friday he drove up and took a pic at Lake Tahoe). He said there were roughly 50 participants including Ferraris, Lamborghinis, five McLarens, and a bunch of other goodies. Oh, and note that he finally finished painting his car – looks about a million times better!

Meanwhile back here I’m pretty happy with how Midlana is running though as mentioned, that engine mount has to be redone. On the side, 2009 is gradually getting put into the archives.

27 Aug 2016

Well that shouldn’t have been a surprise; the new engine mount transmits so much vibration into the car that the mirror goes blurry at certain engine speeds. Fine, a sheet of appropriate-stiffness polyurethane was ordered from Mcmaster and will be cut to suit – still looking for that happy middle ground.

26 Aug 2016

Before starting on the ducting there’s something that’s been a bit of a nuisance, but first some back story:

Honda FWD drivetrains use four engine mounts. The left and right mounts near the front pulley and rear of the transaxle support the drivetrain weight and are designed to filter out vibration during steady-state driving. The front and rear mounts on the other hand handle  engine torque. After one mount broke, aftermarket mounts were swapped in even though I’d heard they introduced more vibration, and boy did they, bad enough that OEM units were swapped back in for the weight-baring units, leaving aftermarket units to handle the torque.

Because the car was designed around OEM mounts, the front aftermarket mount didn’t fit and had to be redesigned, while the rear mount was pretty much forgotten about. When the engine was last removed, the rear engine mount was badly distorted, but when the engine went back it, it looked fine and was left as-is. Well all that turbo torque again severely distorted it. When the engine drives the car forward, it tries to rotate backwards, trying to lift the front mount and compress the rear mount. I thought the front mount could handle it but the engine was still rotating, trying to compress the left and right mounts and compressing the rear mount even more, so it had to change.

The correct material is probably stiffer polyurethane but I had a chunk of Delrin, probably not the best choice but it was on-hand. The hole is offset because that’s where the drivetrain wanted to sit with no torque on it. Haven’t driven the car yet and there will probably be more vibration under hard acceleration but so be it.

In other new, this weekend my brother is in Virginia City, Nevada, for their annual hill-climb. He’s got a good chance to place really well since his car is pretty much perfect for something like this. Sure, some of the other hardware is faster, but it’s likely the owners aren’t willing to push them due to a combination of inexperience and fear of bending their very expensive toys.

 

 

23 Aug 2016

I think I’m going with the intake along the top edge of the windscreen. As the pictures show, there’s an area aft of the X-tubes and forward of the main roll hoop where a duct could duck (sorry) down and keep the overall profile low. The more I look at it the more it seems like the best compromise. It could turn into a substantial project though, with the duct being an integrated part of a roof with future provisions for doors. Someone who’s been down this road recommends a duct area no less than 25% of the intercooler area – that’s doable with this layout. It means that the duct could be as narrow as 3″ wide as seen from behind, and in the rear view mirror – yes, I haven’t let that go yet. Another plus is that if and when a rear wing is needed for track events, the duct work will be well out of the way airflow-wise.

22 Aug 2016

Wow have I heard back, okay, OKAY, it’s unanimous, “Snorkus” is moving on and will be replaced by… something.

One choice is a low-profile and wider duct that runs to the top edge of the windscreen. A variation is running it below the main hoop and up through the rear portion of the X-tubes. This project could grow into integrating the duct into a roof, which further downstream will serve future door/windows.

Another approach is two ducts, one off each side feeding inward. The problem is that they’ll totally block the rear view mirror, including the blind spots, which I may just have to accept but am not happy about.

21 Aug 2016

“I shall call her ‘Snorkus.’ ” It’s rather… huge, and the square corners make it worse visually. Like I posted on Instagram, if it wasn’t my car I’d think it was rather, what, adolescent?

I realized I have an odd personality, like movie stars who want attention for their careers, yet oddly think they’ll be left along when shopping for groceries. I’m kinda like that – minus the money and fame. So why did I build Midlana if I don’t want attention? Well the idea was that it would get attention in a understated way, not “HEY, over here, look at me, wanna race?!”

I have to think it over, though how much do I care about what people think? It’s purely functional, but it isn’t very attractive as it sits. I admit I have no idea how big the inlet needs to be but it was copied from a Nissan GTP car. I had no intension on going with composite construction until I saw it on the car. Composite’s a pain, smelly and really messy but it does allow getting rid of all the hard edges and corners.

In more objective news, the car took a huge step forward today. A test drive with the new exhaust shows MAP is well under control, flat-topped with n0 evidence of wanting to increase further. Granted it wasn’t run to 8000 rpm (the crazy plot at the bottom was it rev-limiting at 7000 rpm) but I don’t expect anything nasty. Also notice the speed is 91 mph; running it to 8000 in third means 104 mph, all the more reason to be brief and in a remote area, or just not do it at all.

Lastly, boost controller duty cycle was measured vs. the boost it produced and closed-loop boost control was reenabled. Didn’t have time to do a test drive but the results will be used to further dial in loop settings. Feels good to be driving the car again.

20 Aug 2016

It came out pretty nice and will look even better after the screen is added. Before that happens though I’d like to get the scoop done.

Oh, notice the drip pan? There’s an oil leak somewhere on the engine. When it’s running it doesn’t leak because the dry sump pump draws a vacuum in the block and keeps it from dripping. But oddly, there’s enough oil somewhere that for about 5 days after the car’s parked, it drips. Note that another feature of a dry sump system is that the oil lives in a remote tank, not in the pan, so that’s probably not the source.  Because I’m always distracted by other stuff I haven’t traced it to its source, but it seems to be about half way up the front cover. That kinda sucks because to get the front cover off is very invasive, bad enough that I’d probably leave it. I’m hoping I can clean it all off and check it ever few hours to find the source, then go from there.

17 Aug 2016

Bah! Went out to start the car with the new setup to, you know, see if there any leaks. No need – the puddle under the car saved me the trouble. Turns out the new wastegates come with AN water fitting adaptors that seal with aluminum washers – if only they were the right size. For some reason they were larger than seemed necessary – I noticed when installing them but figure if they work, they work. They didn’t. When installed, they shift to one side and are just large enough that the edge gets squeezed out to beyond the sealing face and presto, a slow drip. Gasket-sealer was used and time will tell if it puts up with the heat. It should since it’s just sealing water passages, but still, there’s mighty hot stuff not far away. Not a big deal, if it leaks, proper-sized aluminum or copper washers will be used – or maybe I’ll order washers now to have them on-hand.

Haven’t driven the car yet – the heat and humidity takes all the fun out of it, never mind rush-hour traffic. Then there’s its “danglies” hanging down in back, the two unrestrained wastegate tubes free to swing around. I’m working on the hold-down for that now.