FJ60 (FLYBOX) -> 2F -> 13Bt -> 15BFT (1 Viewer)
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Sorry if this is mansplaining a bit:
It's not really due to how old the tech is unless comparing IDI vs DI diesels, 6cyl are more comfortable for passenger vehicles due to piston size and vibration frequency. The 4cyl will usually have more perceptible vibration than an equivalent 6cyl as the frequency is lower so even if the pistons/forces were the same size the vibration would "feel" smoother on a 6cyl
Also, the pistons on a 4cyl are usually also much larger than an equivalent 6cyl, so not only is the frequency lower making the vibration more perceptible, the forces themselves from each cylinder pulse and oscillating mass are usually larger:
eg 3.4L 3B = 0.85 L/piston vs 4.0L 2H = 0.66 L/piston
or 4.1L 15BFT = 1.025 L/piston vs 4.2L 1HDFT = 0.7 L/piston
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- #63
Got today the intercooler parts. $170 to TIG the elbows on the radiator and the piping. All cost $430 not including the 4 silicone jointer and hose claps. I had some straight left over 2.5” piping from the troopy build.
One key issue is that I stop by their shop every time I’m at Costco and leave a 6 pack of Toblerone.
One key issue is that I stop by their shop every time I’m at Costco and leave a 6 pack of Toblerone.
The reason for an inline 6 being much smoother than an inline 4 is more fundamental and not related to piston size, and is only in part related to higher firing frequency at the same rotational speed - it's about primary (crankshaft frequency) and secondary (twice crankshaft frequency) balance. In short, an inline 6 has perfect primary and secondary balance, and an inline four has both primary and secondary imbalances. Hence you see balance shafts in some inline 4s (e.g. the 3RZ), but never in an inline 6. I guess Toyota did not put a balance shaft in the B engines as they are not aime at passenger comfort.
As for DI v IDI, I would guess that DI engines are moother in part because they have a lower compression ratio (e.g. 17.8 in a 14B-T vs 20 in a 3B or 22 in a 2L) but for the most part I would expect the engines to get worse with age as differences in cylinder pressure, injector opening pressure, fuel delivery pressure start to appear.
Increasing the idle speed might help the vibration (and save your LH engine mount).
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- #65
I shortened the stainless pipes and put longer silicone couplers. I can always cut the stainless shorter…
By the way, you still need photos of the AC bracket? @TRAIL TAILOR I think can make one for the stock compressor. Jason is an absolute fantastic designer/fabricator.
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NVH is directly related to swept volume and piston size. All of the forces which cause the vibration in the first place are directly proportional to the mass and geometry of the components and the associated combustion forces. Balancing counteracts the forces which cause vibration, it can't eliminate them entirely, especially combustion forces as those forces vary. Yes, a 6cyl can be inherently better balanced by design, but it doesn't negate the fact that larger engine components create larger forces to begin with. Similar engines of the same basic design but of different displacement will result in different NVH
I didn't mention primary and secondary balance because most mud members are not physicists / engineers and would have to go down the rabbit hole for a few hours to get a grasp of those theories as they are not as intuitive. However, combustion forces are dynamic in nature and vary in ways which component based engine balancing does not. There is always a compromise, and engines with larger components create larger dynamic combustion forces
While RPM affects the combustion process, it is odd to argue that higher firing frequency doesn't affect the subjective resultant NVH. All other things being equal, higher firing frequencies are somewhat universally subjectively perceived to have less NVH; engines almost always subjectively "smooth out" at higher RPM independent of combustion forces and combustion efficiency even where the engine RPM exceeds the capabilities of the IP/timing. Conversely, the varying dynamic combustion forces on/off the accelerator and the associated NVH is usually more apparent at low combustion frequency / RPM. Just like sound, we perceive magnitude of vibrations differently at varying frequency
One of the main factors with perceived NVH between DI and IDI is that DI run far better from cold; most Toyota DI's will start in a moderate climate without requiring glow or combustion chamber warm-up. The subjective impression when getting into a vehicle with a DI diesel is a smoother and more refined experience from the start of the engine, whereas most IDI's require some time to warm up before they smooth out at idle.
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If you haven't already, get a bead rolled onto the pipe ends to avoid the silicone hoses blowing off
While you don't have a throttle/butterfly to slam shut and cause a peak in IC pressures, the wide style stainless hose clamps spread the force over a larger area and there's debate over their effectiveness. Pure speculation on my part, but I think they may be designed with aluminium piping in mind to avoid it being crushed
eBay spec bead rollers are now very affordable, just be sure to "wear the gears in" as they're a bit crunchy from factory and go easy on stainless or the chinesium may not hold up
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- #69
I have built 4 of these intercoolers. One boosted to 18 psi. All stainless. Some bead blasted. Never poped. I guess there could always be a first time.
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- #70
Managed to crank the engine. I did not install the last pipe of the intercooler to clear out the system. Does not seem to get fuel into the engine. The prime pump is leaking badly and I suspect it’s injecting air. I also disconnected the vacuum cutoff diaphragm. I hope the engine shutoff is vacuum ON and not atmospheric pressure. 
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Managed to crank the engine. I did not install the last pipe of the intercooler to clear out the system. Does not seem to get fuel into the engine. The prime pump is leaking badly and I suspect it’s injecting air. I also disconnected the vacuum cutoff diaphragm. I hope the engine shutoff is vacuum ON and not atmospheric pressure.
When I pallet started my 15BFT I don't think I had to do anything with the vac line to shutoff diaphragm except pull the lever at the IP manually to stop the engine
The primers up on the filter housing are terrible, it seems every person with a 15BFT has the leaking issue and they have to be replaced. Can only buy OEM as noone has found aftermarket in correct thread saize AFAIA. I've had a quick look and you might be able to fit the generic Bosch style on the inline pump similar to the 3B but the fuel return is in the way so would need to check that rotating it won't affect anything
My primer leaked as soon as it was opened. Just replace it. These are notorious for being a PITA to bleed but once they fire it should start up effortlessly on the first crank every time. A friend had some luck lightly pressurising his fuel tank to get it primed
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- #72
Thx. Yes, it made signs yesterday on the last crank. I just had a few min to work on it because was working with my son on his 2004 sprinter van. It WILL start today.
Great news! I was getting a bit worried when there wasn't a follow up post on Wednesday
What was holding it up in the end? Just being a PITA to bleed and / or fill the injector lines like the 15BFT's are known for?
Waiting for the obligatory first start vid
What was holding it up in the end? Just being a PITA to bleed and / or fill the injector lines like the 15BFT's are known for?
Waiting for the obligatory first start vid
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- #75
Hahaha. No. My son has 2004 ex FedEx sprinter van build with heated hydraulic floors and I was helping him so he can leave yesterday to visit friends in UT. They drove all night to SLC.Great news! I was getting a bit worried when there wasn't a follow up post on Wednesday
What was holding it up in the end? Just being a PITA to bleed and / or fill the injector lines like the 15BFT's are known for?
Waiting for the obligatory first start vid
All good.
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- #76
The big test. After 40 miles in town we took it today on a 500 miles round trip to Tahoe. Cruising at 60-65 mph all in 5th gear including the climbs to the Sierras it pulled really nice. EGT never exceed 850 and mpg around 25. I’ll get an exact number tomorrow. It was all in a snow storm. Had all the tools in the back just in case. Never used them. Max boost with this tiny turbo is a bit over 10 psi.
Was this with factory wastegate/setting?
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- #79
Yes. Never did anything to the setting. Seems like the engine can use more fuel to get more power. It does not accelerate as fast as the 13Bt but once it goes, it’s like a freight train. Does not smoke at all. Engine temperature and pressure were rock solid.
Off the top of my head the 15BFT factory setting is ~8PSI so that sounds about right
@Redbj40 should be able to give some tips on dialling some more fuel into it!
Just have to watch the little CT12B isn't working too hard, there might be anecdotal tuning info from 1KZT applications as to what max flow/pressure they can be pushed to, etc
