Whether or not the alternator gets swapped out, it looks like its wiring needs revisiting. The alternator connects through the fuse box to the battery. The catch is, I added a battery cut-off switch upstream of the fuse box and bad things can happen if the switch is opened with the engine running. At best, the engine quits as it should, though I now think it won’t. Since the alternator feeds in downstream of the switch, it would likely self-power the system and the engine would keep running. At worst, not only would the engine keep running, but with no voltage reference, the alternator could generate voltage spikes high enough to damage the ECU. I’m too chicken to try it and find out.
The alternator feed-in point needs to moved directly to the battery. As a related issue, the wire connecting the alternator to the battery is way too small (I blame the Painless Wiring kit but should have known better). It’s 10-gauge but needs to be much larger; the PowerMaster site claims that a 7-ft wire running 125 amps requires at least #6, if not #4. Yes, 125A is extreme, but having everything on in stop-and-go traffic with a flat battery could get there, albeit briefly. Wire size doesn’t seem like it could be the sole cause of the voltage drop, but it can’t be entirely ruled out either. Copper has a positive temperature coefficient, meaning the hotter it is, the more resistance it has, which causes voltage drops with current (this is why a hot starter won’t crank an engine). Still, air temperature rising only 20C wouldn’t be enough to account for the problem… only there’s more to it. The alternator wire runs down the center tunnel, sharing space with the coolant pipes. There’s a fair chance that it’s seeing around 60C or so, increasing resistance by around 16%. That still doesn’t fully explain the situation because the wire temperature in the center tunnel likely doesn’t vary much. Guess I just have to try it to see; right now I still think there’s still a good chance the problem is an overly-sensitive voltage regulator in the alternator. Regardless, the alternator wire needs to be upgraded no matter what alternator is used, so this is a cheap experiment before spending money on other things.
Received the replacement coolant temperature sensor and finally checked its calibration… well, let me back up.
An authentic Honda coolant temperature sensor is roughly $45 online, and me being a cheapskate, looked for alternatives. Found one on Ebay for about $8, with the picture showing the sensor next to an authentic Honda part bag with the correct number on it. I knew better than to think it was actually what the picture portrayed and bought it anyway. Sure enough it arrived in a plain box with no markings whatsoever, so no surprise it’s a knockoff.
Boiling water in a Thermos was placed in the engine compartment where the wire harness could reach. The new sensor was plugged in, and it and an accurate mercury thermometer were submerged in the hot water. The sensors were allowed to settle for several minutes and then the temperature read; the thermometer settled out at 91C, while the sensor read 77C. Sigh, it wasn’t expected to read exactly right but this is kind of ridiculous. To be fair, I don’t know how accurate an authentic Honda part is, but doubt it’s that bad. We’ll see since a “real” sensor has been ordered.
Took Midlana and the granddaughter to the new Cars and Coffee location, currently at the Outlet San Clemente mall (one can only wonder how long it’ll be before they get thrown out from there as well, which seems to be the fate of the event, for noise, exhibition of speed, etc). This was the first time she’d been to any car show and, it went about as expected, not much interest, but the point was to expose her to it at least once so she knows they exist and what it’s about. I told her that I’d be happy to take her again but she has to ask – I won’t pester her to go.
No good deed goes unpunished and the traffic for the 50-mile trip home was brutal. The clutch was used about a million times because even at idle in first, Midlana wanted to move along faster than traffic. Being around 28 C didn’t help but it was a good test of the updated cooling system; coolant got up to around 90C but no higher. On the way up it was the exact opposite temperature-wise, dipping as low as 6C, brrrr. With such low temperatures, engine coolant only got up to about 80C.
Speaking of that, I’ve been watching how alternator voltage varies with temperature. In cold weather, charging voltage is 14.1V, perfect, and turning on the radiator fan caused it to drop to about 13.5V, still pretty good. On the way home in the heat though, charging voltage slowly dropped off to around 13.6V and dropped to 12.9V with the fan on. I was going to check to see whether the Chevy pickup alternator I’m using has an “S” input (Remote Sense). As I type this though, I just realized it doesn’t matter if it does or not. If there was a voltage drop problem at higher air temperature, it would still be there in cooler weather, but the problem is only during warm weather, ruling that out. It’s not like the alternator is being overheated either; right now there’s neither an engine cover nor belly pan. Also, since this is a cross-flow engine with the alternator on the intake side, it’s not near anything hot. I suspect the built-in alternator regulator just isn’t very good over temperature.
I could try running a cold air hose from the side vent to the alternator, but related to the above, since it’s already fairly well ventilated, there’s a good chance that the “cool air” being fed to it through a hose from the outside isn’t much lower than the air already swirling around the engine compartment. Of course, zooming way out on the problem, I’m not sure how much it matters. That is, it’s been this way for years and hasn’t been an issue, though I do keep a battery tender on it when in the garage. Then, during the endless traffic jam yesterday, I managed to stall it once and forgot the radiator fan was still on; when cranking, the battery clearly wasn’t happy at all about having to run both (sounding like a run-down battery). So there’s several approaches: do nothing, get the aftermarket alternator and hope it’s less temperature sensitive, or set up a cooling air duct for the existing unit and hope the outside air is a lot cooler than engine compartment air.
Finished the radiator ducting, though it still needs paint before being permanently mounted. It was assembled with temporary rivets and Midlana was taken out for a drive, again confirming a 2-3 degree C decrease in coolant temperature under all conditions.
Twice now the same cylinder head exhaust manifold bolt has backed out, the first time completely and the second time about a centimeter. Not sure why since it’s torqued to Remflex’s recommended 20 ft-lbs. It was okay after today’s drive but if it does it again it’ll be safety-wired.
Went on a longer test drive into the back country, up “my” Palomar Mountain “test track”. This time there was an interesting mix of events.
At the base of Palomar Mountain, they were fishing a balled-up sportbike out of a ditch, the driver nowhere around. Heading up the mountain I got stuck behind a cruiser Harley where the rider was apparently still learning to ride. That’s fine, except he was going between 22 and 32 mph, I checked. At first I was polite – everyone starts somewhere – but after a while it got kind of annoying as he kept passing places he could have pulled over. And then…
After ruining about 80% of my ride up, a Harley was coming down the hill the opposite direction and correctly assessed my situation in a flash. It was quietly hysterical what he did, first tapping his helmet and then giving a palm-up gesture toward the Harley, like, “dude, how long you been holding him up?” I don’t know if the Harley ahead of me finally noticed me, or if the guilt worked, but he immediately pulled over. I had a very hard time to not laugh as I gave him a thank-you wave.
After I passed the Harley I went tearing up the rest of the hill, trying to make the best of my shortened “course.” The new tires are, well, amazing. The old ones had really lost their stick because these new ones are pretty incredible. I haven’t even managed to slide the car yet because doing so means going into a turn fast enough that if it does become unstuck, I’d likely end up in the ditch along with the sportbikes. Speaking of that, came around a turn and there was a second sportbike being retrieved from the rocks. Not far away, a cop was making an accident report but heard me coming and had a good long look at me as I came by… I waved to acknowledge, “yes, I know you see me and are thinking ‘how can that be legal’, and that I’m cutting it close.” Thankfully all I got was the look.
All the way up, coolant temperature stayed lower than it had on previous drives – I’m happy. Drove around the top of the mountain a bit then headed back down. This time I had a Harley behind me who wanted to play. I let him pass and once past the cop, we had some fun heading down the hill. I’m curious how I would have done behind a real sportbike, but that puts us both in a situation where things get serious. I previously wrote that I always wanted a car that could keep up with sportbikes heading up the hill and I may well have that. The thing is, there’s a small chance that one or both of us might go off (as said above, two bikes already had). If he went off with me right behind him, I’d stop, and then things could get really interesting, like, would he sue me because I was pressuring him, him hoping to avoid his share of responsibility?* Would the cops arrest us for street racing? Serious thoughts – or maybe I’m just old. I passed a group of sportbikers at the base of the mountain, apparently grouping for another “assault”, and sure enough, they got all excided when they saw Midlana. I waved, but decided that stopping and getting involved might not be wise.
Oh, I got my very first thumb’s-up from a Harley rider, the first out of the 500 or so I’ve passed over the years. Meanwhile, sportbike riders give enthusiastic thumbs-ups about 30% of the time – I have theories.
On the way back, passed the local university and a car pulled up alongside with several hot and crazy college girls, screaming how “sick” my car is. Ah, if I were but young and single…
During the weekend’s drives, the alternator may or may not have been acting up. It normally stays mid-13Vs, which is a little low and is why I’m considering an aftermarket adjustable unit. It’s as if my alternator heard my thoughts because now it’s charging at around 14V, which it’s never done before. Also different is that with the radiator fan on, a few times at least, voltage sagged down into the 12.XV range, which was new. Checked for loose wires and found nothing.
No bites on the transmission, but at $4000, it’s not surprising that it may take a while. The price is what it is because of the work done to ensure it’s as close to “new” as something used can be, so for now I wait. We’ll see if and when my idea of its worth matches anyone else’s!
I have all the parts to start building the rear wing, and at some point I also have to figure out airflow in the proposed location (how high it needs to mount to be in clean air). There are various ideas, one involving smoke bombs… that could be interesting…
Lastly, I tried fixing something that’s low on the annoyance scale but there nonetheless – the perpetually-crocked steering wheel. It’s because the splines on the steering wheel adaptor are fairly course, so it’s either wrong in this direction or that direction, take your pick. I finally realized that the Miata splines further down the steering column are more fine-pitch, probably around double, so I tried offsetting it by one spline, and it’s much better now.
*There’s currently a lawsuit between a sportbike rider and Laguna Seca Raceway. He had gone off-course and hit some sandbags, which threw him off. He’s claiming that Laguna unnecessarily made the track dangerous and caused him to lose control. Well, what was he doing off course if he hadn’t already lost control, but anyway, people sue for all sorts of reasons.
Went to the local hot rod show with my brother. He wanted to talk to Tremec, his transmission builder, about how the front of his case has cracked, something that’s reportedly happened to other people as well, but wasn’t much satisfied with their answers, which were a little wishy-washy. I told him the right ($$$$) solution is to suck it up and buy their next model up in strength, else the probably may well happen again. The first picture with my hand on the gears is one of their upper models. Yeah, those gears look like they could handle some pretty good torque.
The rusty white truck had a turbo about twice as large as mine, with an air cleaner about 0 times smaller than mine – yeah, it shows signs of collapse.
The yellow and red show car looks like something the Simpson’s or a few Minions should be driving.
The green truck had a complete 425 (or 455) c.i. Oldsmobile Toronado in the truck bed. The picture from the side shows just how compact the drivetrain is, with the engine sitting directly over axle centerline. Compact yes, light, nope.
That tire? A “405/25-24”. I fear tires are still heading up in size.
The engine with the bluish valve covers isn’t anything remarkable, but the fuel and nitrous plumbing was “noticeable.”
There were a few rat rods, and then there was what appeared to be a very old stock vehicle, but it turned out he’d created it from authentic odds and ends from that era, including a V12 out of something. Another car had a V12 in it as well; the header fabrication would have been a fun project.
The light blue/silver car was amazing, kit or otherwise, as was the period correct engine in another car.
And then we come to our favorite, the ratty-looking pale green Chevy truck. We’d have walked right by it had we not just seen it at the autocross. Watching it approach the first turn we both said out loud “he’s never going to make that”, and then did. The thing was flat-out amazing, beating about 90% of everything else. The secret is its Corvette chassis, suspension, and drivetrain, but you couldn’t tell from the outside, though the huge brakes are a hint. The interior looks much like an old 1960’s truck, albeit with racing seats. He’s looking forward to taking it to a trackday, and it would be pretty funny seeing him pass “real sports cars.”
Went for a couple test drives to get more comfortable with the new transmission and the close ratios. Something else though, came to light during the drives that consumed my attention.
Ever since the engine was retuned I noticed that coolant temperature seemed a little higher. It wasn’t a lot though and since coolant temperature is affected somewhat by outside air temperature, it was never really clear if it really was or not.
As mentioned before, Midlana has always had this somewhat odd trait where when idling with the fan on, coolant temperature is fine (mid-80s, C of course), and when on-track and driving hard, coolant temperature is about the same. But then there’s just plodding along on the freeway at 65-75 mph. One would think in that low-power situation, coolant temperature should again be about the same, only it isn’t. Given enough time, the temperature very slowly creeps its way up to around 90C, and this weekend on the freeway while going up a long incline, it hit a new record of 93C. If it was the middle of summer it wouldn’t have been as big a deal, but outside air temperature was only 17C.
There’s about a dozen things that could be going on, and in no particular order: radiator too small, weak electric water pump (or plumbed backwards(!), mechanical water pump turning the wrong way(!), defective coolant temperature sensor, air going around the radiator, big air bubble in the cooling system somewhere, engine timing, a collapsing hose or obstruction, low coolant, or maybe something I’m missing.
First, a back story regarding pumps, which involves Kimini, predecessor to Midlana. Kimini’s new owner added an electric water pump to help move coolant from the mid-mounted engine to the radiator and back. It apparently worked well enough that he stopped paying attention to coolant temperature, because soon after, the engine was destroyed due to severe overheating. Turns out that he’d wired/plumbed the pump so it was moving coolant the opposite direction as the engine’s mechanical pump! This caused very interesting symptoms – had he noticed. At idle, the electric pump probably won the tug of war regarding flow direction, so it stayed cool. At freeways speed, the mechanical pump, now spinning fastest, probably won the fight, moving coolant the opposite direction. But consider the case of driving at some magic lower speed where the flow generated by the mechanical and electric water pump perfectly balances. At that speed, coolant flow through the engine is zero – end of story, and end of engine.
As a sanity check, both pumps were checked for proper rotation; the mechanical pump because I’d rerouted the belt, and the electric pump, just because. Both were fine, so they’re off the list.
To keep from wastefully replacing stuff, the car was warmed up to an indicated 80C, then the radiator cap on the header tank removed and the temperature measured with an accurate mercury thermometer, which read about 68C. At first it seemed like “ah hah”, but probably not because the header tank is filled by two bleeder hoses, a small one from the cylinder head, and a larger one from the top of the radiator. It’s likely that the header tank will always be somewhat cooler than the coolant measured by the sensor itself inside the cylinder head. That said, I’m going to buy a new coolant sender anyway, plug it into the harness outside the cylinder head, and put it and the thermometer in a heated container of water. The reason is because an inaccurate calibration of one of the ECU manufacturer’s default Honda sensors has already been identified. I’ve never tested the coolant sensor so this would be a good reality check.
Another reason the header temperature might be inaccurate is because coolant flowing from the engine to the radiator flows first through an oil-to-coolant heat exchanger, which can add or subtract heat depending upon oil temperature.
Because of the bleed lines, I don’t believe it’s possible for a big air bubble to be trapped in the cooling system; it’s self-purging by design so that’s off the list. The radiator being too small doesn’t fit either, since it works fine under hard use at the track. Coolant level is fine; I don’t think (without proof) that there’s any obstructions because I only use distilled water and Water-Wetter. That leaves air going around the radiator… hmm.
As a quick test, rags were stuffed around the radiator where I could reach and another test drive performed. Well huh – taking the very same route, at the same speeds, and in the same weather, coolant temperature struggled to reach 90C, and when I let off, it dropped faster than before. This leads to the theory that at idle with the fan on, air gets sucked through the radiator by the fan, so the gaps around the sides don’t matter. At speed on-track, there’s so much air coming in that even with the leaks, there’s sufficient air flowing through the core that cooling is sufficient. That leaves the freeway situation. Here, there’s less air coming in the nose and maybe half (a big guess) is going around rather that through the radiator and providing insufficient cooling. It’s just a theory but seems to fit the facts. So first thing was to cut off the support for the horn (it sticks around the side of the radiator and makes sealing it in that area impossible). The horn will be relocated behind the radiator. Paper templates are being made for aluminum panels to extend from the inside of the nose cone to the forward face of the radiator, with foam between the two. This is so when lifting the front cover, the panels sealing the radiator will move away from it without snagging on anything.
So things look promising, though it’s something I should have done back when the car was built. Of course back then there was a big push to get it on the road, so some things got pushed off.
Oh, and there’s one other variable – ignition timing. From my understanding, timing really affects how much heat gets pushed into the cooling system. The tuner noted that he advanced timing quite a bit, so it may well be that that’s the source of the higher coolant temperatures.
Lastly, I’ve been trying to find what the normal coolant operating temperature is for a Honda K24, something that’s surprisingly vague and variable. It seems to be somewhere between 80-95C, so it’s not like the engine is overheating. This motivation to get to the bottom of this came from seeing temperatures it had never reached before, so adding the radiator ducting is the right thing to do, regardless.
Looks like the lower most layer or two need stiffening up, which is now easy enough to do.
I enabled the HDR-AS300’s GPS overlay and while it’s interesting, it may prove to be something of a novelty since GPS speed lags so far behind (how does my dash keep up with the same data?). The route information is interesting, but again, not sure how useful it’ll prove to be.
Forgot to mention yesterday that the transmission shifts so easily, I twice shifted into the wrong gear. Doing so while just cruising (like I was) isn’t a big deal, but having that happen on-track is a different story. Going to have to get better accustomed to the new gears, syncros, and shifting effort.
Lastly, my dog-box transmission is being boxed up and shipped home. Once it’s here it’ll officially be for sale.
Spent the weekend building the new rear engine mount, which took way longer than expected. Part of this is my own doing though, because with Kimini, I planned everything out to an extreme and as a result, fabrication went smoothly and very little had to be redone. With parts of Midlana though, I’ve been testing how much I can “wing it” and still have it turn out right – this one just made it.
The plan was to have the engine mount rubber “field-tunable”. The OEM mount works fine in an OEM application – but not so much with 400+ ft-lbs of torque. Also, applying torque to the side of a bolt in a rubber-filled tube just doesn’t work well when a lot of force is applied because it’s so concentrated. That’s why a 2″ x 4″ steel “foot” is used to spread out the load and rests between layers of polyurethane sheet. Being a rear engine mount on a clockwise-spinning engine means that the layers below handle acceleration torque and the layers above handle deceleration. This allows using different durometer rubber for each layer. So the prototype was built but the unknown was how much it would deflect under power and deceleration – and how much vibration would be transferred to the chassis.
“If only I was able to watch it.” Presto, that’s what the new Sony camcorder is for, so it was attached to a rear tube and aimed at the engine mount. About now you’re probably looking for the link – well, there isn’t one yet. It’s late, the camera’s new, and I have to figure out its editor. Hopefully it’ll be good enough else I’ll have to find a “real” video editor. I watched the raw video and it’s pretty cool what you can see and hear – I’ll post it up sometime this week.
In other news – the clutch! With the new transmission having synchros instead of dog engagement, I again used Competition Clutch’s instructions to set the clutch stop for the twin-disc clutch. With the dog-box, I couldn’t set it as instructed because it would instantly drop into gear even without the clutch. The instructions say to gently push the gear lever like you’re going into a gear, while at the same time slowly depressing the clutch. At some point it’ll drop in, then push the pedal another 1/4″ and set the clutch stop there. Well, I did, and holy smokes does it change the character of the car. Clutch throw is now much shorter and with the close gear ratios, it makes shifting much faster. I’m really happy how that turned out.
Every now and then I get caught up in the excitement of buying stuff for the car but getting too far ahead of what’s needed right now, such as wanting to pick up aluminum stock for the wing while the rear engine mount isn’t complete. I learned the hard way that if I have parts on-hand for half a dozen project, I actually make slower headway than if I just focus on one at a time.
Somewhat related, before the wings are built, air flow over the car needs to be researched, and the new Sony camcorder should help that happen.
Then there’s the higher-output alternator which was almost ordered, but again, first things first. Even when it does percolate to the top of the list, it needs to be seen if just running cool air to it might be enough.
Just remembered another task – radiator ducting. The car never overheats, but when cruising at freeway speed, coolant temperature gets higher than when driving hard on the track – why is that? The theory is that some (or even a lot) of the air coming in the nose goes around the radiator instead of through it. At freeway speed, there may be insufficient flow through the fins to carry away all the heat, but at high speed, even with much of it going around, there’s still plenty left over for actual cooling. Will probably tape up some cardboard and see if the theory’s correct.