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 8 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.
Weather cleared up so an 80-mile drive broke in the new gears/synchros/LSD. Observations:
The ratios are noticeable closer, which isn’t a surprise but I kept catching myself pausing between gears, waiting to match gear speeds, a habit learned with the straight-cut gears, but when I let the clutch out with the new gear set, it’s clear I’m waiting too long. That’ll solve itself with time.
During the drive, 80 mph (GPS) was 4000 rpm, so back-calculating, the rolling diameter of the tires at speed is 25.1 inches (they compress about 0.5″ due to running ~15psi). That rpm is a bit high for cruising and will ironically serve to keep me more in line, read: driving slower on the freeway. Another reason to slow a bit is because boost is right there and ready to go by 4000 rpm, so it’s like riding a thoroughbred racehorse at a trot but who is ready to go right now. A third reason is that when in boost, fuel mileage takes a nosedive. That said, though the rpm is where MAP can reach maximum, since the throttle’s mostly closed, it’s only about 60 KPa (40 KPa below ambient). I read somewhere that a turbocharged engine can actually improve gas mileage somewhat by overcoming the pumping inefficiencies inherent in gasoline engines due to the throttle plate obstruction. Obviously not a big goal.
(Because of the rolling diameter of the rear tires, if I absolutely must reach 60mph in first gear, I either have to increase the rev limit to 8150 or put enough air in the rear tires to increase the OD to 25.6″, hah.)
After the drive, the OEM transmission fluid used for break-in was drained and replaced by magic oil supplied by the gear manufacture in unmarked bottles. Went for a short drive for gas and it “seems” to shift a bit easier, though it could also be my imagination. I assume it’s going to take several hundred miles for the carbon synchros to wear-in. Speaking of oil, I had an issue with the old transmission where the gear manufacturer, PPG, recommended brand X, while WaveTrac specifically recommended not using brand X. With the new transmission it’s similar, with Gear-X recommending their stuff (of course) and Giken recommending their stuff (of course) which, of course, wasn’t the same. I ended up getting both of them to hash it out on a group email and Giken finally said that Gear-X’s mystery oil would be fine.
There hasn’t been a peep out of the limited slip, or maybe I can’t hear it. Some people complain that Gikens makes noise, though others say it’s silent. Doesn’t matter either way, just a note.
If there was any question before, the test drive confirmed for sure that the engine mount has to be redone – way too much vibration.
During the test drive, logger data was used to recalibrate the ECU’s calculated “gear”. The transmission doesn’t produce gear position directly but the ECU has the variables to create one. It’s handy for various things, such as boost-by-gear. Speaking of that, boost in 5th and 6th was increased (back) to the maximum value – that’ll be fun. Assuming it’s clear this weekend I’ll do a longer drive to fully break in the gears, then change the transmission oil as requested by the gear manufacturer.
I reworked the rear engine mount (which resists torque) while the engine was out but don’t like the result, too much vibration. I have a plan to basically roll my own and I’ll post pictures. The sweet thing is that the new design will make it easy to change the stiffness on the fly.
There’s the wings to make, which is a significant project but since it’s fairly compartmentalized, the car can continue to be driven while that’s underway.
There’s the rear diffuser, and right after that, filling in the gap above it, created when the damaged panel was cut out after my off at Willow Springs. Will probably use screen mesh for that.
Engine cover: Been wanting to redo it for awhile because without it, the car looks unfinished. More concerning though is the small worry about an engine fire at-speed, there’s a strong likelihood that the flames will be swept forward by the swirling air. That would be bad.
Upgrading the alternator. If I’m driving at night in stop-and-go traffic, the lights, electric water pump, radiator fan, fuel pump, and of course the ECU are all on, which is around 80 amps. I’m considering adding a small oil pump and cooler to the transmission (already have both) which moves the total current closer to potentially 90 amps at idle. The OEM Chevy pickup alternator produces around 14V when I first start the car, which is fine, but as it warms up it drops off. On the freeway with just the essentials (water pump and fuel pump), battery voltage ends up around 13.5V, and around 13V at idle when fully warm, lower than I’d like. I’d like to be able to run everything instead of having to sometimes load-shed things as the battery voltage drops off.
There are a couple solutions, like feeding cooling air to the alternator and putting on a slightly smaller-diameter pulley, though it’s being spun about as fast as it should be (18,000 alternator rpm at 8000 engine rpm). I’m currently leaning instead toward a unit that can support everything even at idle, such as the PowerMaster 478618. Better yet, it has remote sense and adjustable output voltage .
Long ago I bought LED signal flashers because the old-school mechanical ones don’t work with LEDs. Until recently, LED car lights weren’t a “thing”, so it’s random chance how the mechanical flasher sockets are wired (since polarity didn’t matter). Of course mine are backwards backwards (both the turn and emergency flasher) so the new LED-compatible flashers don’t work. I’ll have to pull out the fuse block and swap the pins.
Other things on the back burner are adding a transparent bulkhead window behind the seat to see what that does for possibly reducing wind and noise. Then there’s door fabrication. Pretty sure how I want to do them; it just endless details like: material, frame substructure, hinge type, fabrication, and placement, weather stripping, and a latch.
Lastly, I finally had enough of the buggy GoPro and have ordered a Sony action cam.
The pieces of debris are from a synchronizer hub, which is probably the best of all the things it could have been. “Best” meaning that they’re not bits off the expensive aftermarket gears and being an OEM part, it’ll be less expensive to replace. The transmission will be sent to the same place that built the new one, which works out well since they regularly build PPG gearboxes. When the unit is put up for sale, it’ll be advertised as having been verified as 100%-good.
The rain let up so the car was taken out for a short test drive. The new gear ratios are closer, with first gear being the most noticeable. Now, the car sounds much more like a road-racing car when leaving a stop; with the lower ratio, the ratio has to be slipped a bit more. Being new, the synchros are a little sticky but that’s to be expected. It’s true what Honda owners said about these gears (and the ratios) are terrible – for OEM-weight cars.
With everything that was removed and replaced, it was good to see that nothing leaked or fell off. The rebuilt rear engine mount though, is transferring too much vibration. I’ll probably have to redo it again and am considering something like having a block mounted off the engine that in cruise conditions, “hovers” between two rubber-lined stops in the engine mount. That way, vibrations will only be transferred when under hard acceleration. We’ll see.
Got the axle CV cup back, assembled the driver’s-side axle, then filled the transmission with OEM fluid to break it in. With some rare rain going on though, the test drive has to wait.
With the car stuck in the garage, finally got around to added 15-mm wheel spacers, since I’ve long had tire scuff marks on the inboard panels. Adding the spacers necessitates cutting down the OEM wheel studs, which went fine and while I was congratulated myself on my fine work, my brother called. I asked what his tire-to-chassis clearance is and was surprised when he said less than 1″, which is what I had before adding the spacers. Well nuts. He reminded me that the tires I’m now using (same as his) have stiffer sidewalls (though I don’t know how he knows that), so that’s one variable. Another is that he has roughly 450 lbs on each tire, while I have around 600 lbs on the rear tires due to being mid-engine. Another difference is that my rear suspension is IRS, so the tops of the tires move inboard under acceleration and braking. Between all these differences, it’s unknown how much the tires will squirm around. The irony is that having added the spacers and switched tires, while there won’t be any rubbing, I won’t know why. Oh well.
The bad news, well, I’m not sure how bad it is yet.
When I took my old transmission to WaveTrac to have them fix their differential design flaw, I expected them to do just that, pop out the stuck axle stub, fix the LSD, then give me a call. Well, they did:
Them: “While we were in there we also found some gear bits stuck to the magnet. We’re sure you will want to fix this so we’ll hand it back to you taken apart.”
Me: “No, I want it reassembled, then I’ll decide what to do after seeing the little parts.”
They agreed, I drove up to get it yesterday, and:
Them: “Okay, here it is, reassembled but not sealed.”
Them: “We’re sure you’ll want to take it apart, so there was no reason to seal it.”
That isn’t what they agreed to do… Anyway, when they handed me the parts, they did indeed look like broken gear teeth. After thinking it over and looking at them again later, I’m not so sure; the “teeth” on them are really small, flat-topped, and not helical. I’m wondering if they’re off some sort of slider component, though why that would break instead of the gear teeth is a mystery.
Anyway, the first step is to identify what these bits are. At best would be hearing they’re of no consequence (yeah, I know) and at the other extreme, it gets shipped to a tranny shop and torn down – again.