15b/15bfte engine swap (1 Viewer)

[mocha0923]

Is it a BJ7X bellhousing, clutch fork, slave, and B spline H55F that you're using?

I have an H55F with B spline and I found the right starter that fitted well to the back plate and bellhousing, but no info if 12V system. The only remaining issue is to find out if the engine will start. By the way, the oil pan is front sump and have to be chop to clear with the front propeller. Are the two wires from the IP side (facing engine block) is for positive/negative connections? Below is pic showing the accelerator linkage, the 7X bellhousing, H55F, and unknown starter. Thanks!

 

[myusername]

I have an H55F with B spline and I found the right starter that fitted well to the back plate and bellhousing, but no info if 12V system. The only remaining issue is to find out if the engine will start. By the way, the oil pan is front sump and have to be chop to clear with the front propeller. Are the two wires from the IP side (facing engine block) is for positive/negative connections? Below is pic showing the accelerator linkage, the 7X bellhousing, H55F, and unknown starter. Thanks!

The important thing is that you have the starter that fits the bellhousing etc. The motor part can be swapped out for a 12V one if required.

Front hump sump and inline pump suggests to me it's likely 24V from a coaster. AFAIA all 12V sensors from a 3B will fit and are suitable. The sump will potentially need to be removed and swapped for a rear hump sump from a megacruiser, or a modified B/3B one, or a Dyna one with the wings cut off. Note that you need the oil pickup that goes with your chosen sump.

The wires to the IP are tacho related AFAIA and are not required to run. The Coaster tacho is a big integrated dash, so you can't easily swap in a coaster tacho. A custom adjustable tach may be possible, but it would be MUCH easier to run a tacho sender to the bellhousing and use a landcruiser tacho as they were standalone devices.

The only thing required to run is to remove the vacuum line where you have the arrow in your pic, that's the shutoff actuator. This can be actuated by hand to shut off the engine. The accelerator linkage is the one that goes up to the intake. Mine was missing the idle up etc so I can't comment on that. The only vac required is a line from the pump to a VSV, then to the shutoff. The 12V VSV from a 12HT is suitable AFAIA.

 

[heilanpiper]

Hi guys i have a bj70 with a 3b engine that may need a rebuild in the near future, which has got me thinking if i get a 15b diesel for a reasnoble price i may go down this path.

But i have a few questions regarding the 15b as i cannot find much information

I have heard and seen a few conversion but havnt come across much in terms of powrr figure. Is anyone boosting these engines for decent power. What is the most i can get out of one with standard pump and aftermarket turbo?

Also what is prefered the 15b or 15btfe? The later being ecu controlled do i need to remove the ecu and wiring from the truck it come from? And hiw do you tune the ecu for more power.?


Thanks

Frankly, I have put my BJ60 3B-TiC up against a BJ7* with 13B-T and I have way more power and usable low end torque. Toyota should never have chosen the CT26 for 13B-T (can’t speak on 15bt* as I never seen or tested one). It is way easier to design and build my turbo intercooled 3B than to find another engine.

I matched the best turbo for the engine and as I run an MB shop, I used an MB K26 turbo out of the OM617.

 

[GTSSportCoupe]

Frankly, I have put my BJ60 3B-TiC up against a BJ7* with 13B-T and I have way more power and usable low end torque. Toyota should never have chosen the CT26 for 13B-T (can’t speak on 15bt* as I never seen or tested one). It is way easier to design and build my turbo intercooled 3B than to find another engine.

I matched the best turbo for the engine and as I run an MB shop, I used an MB K26 turbo out of the OM617.

15BFT(E) uses CT12B. Same turbo as 1KZTE. Much smaller than CT26. Must give fast response on that big motor.

 

[myusername]

15BFT(E) uses CT12B. Same turbo as 1KZTE. Much smaller than CT26. Must give fast response on that big motor.

15BFT is designed to get a bus moving along, the CT12B is potentially a bit small. CT26 was spec'd on Toyota 6cyl with a similar displacement to the 15BF blocks, the 13BT is 3.4L whereas the 15BFT is 20% larger displacement at 4.1L. The CT12B is probably well sized to the 13BT if you want better spool up etc without chasing high numbers. Mate has a Gturbo 12HT spec on his 15BFT and it goes well with the fuel capability of the inline pump pretty much maxed out according to his tuner.

The direct injection diesels are MUCH smoother than the tractor like rattly indirect injected versions. The 13BT is basically a 3B with improvements, so the only reason a 3B + turbo would go better is more fuel and boost? The 3B also will be lacking the boost compensator on the pump, so there's less ability to tune fueling for on/off boost conditions which is not ideal when the 3B head is known for cracking especially between valves and the precups etc.

 

[heilanpiper]

15BFT is designed to get a bus moving along, the CT12B is potentially a bit small. CT26 was spec'd on Toyota 6cyl with a similar displacement to the 15BF blocks, the 13BT is 3.4L whereas the 15BFT is 20% larger displacement at 4.1L. The CT12B is probably well sized to the 13BT if you want better spool up etc without chasing high numbers. Mate has a Gturbo 12HT spec on his 15BFT and it goes well with the fuel capability of the inline pump pretty much maxed out according to his tuner.

The direct injection diesels are MUCH smoother than the tractor like rattly indirect injected versions. The 13BT is basically a 3B with improvements, so the only reason a 3B + turbo would go better is more fuel and boost? The 3B also will be lacking the boost compensator on the pump, so there's less ability to tune fueling for on/off boost conditions which is not ideal when the 3B head is known for cracking especially between valves and the precups etc.

We lack availability of Coaster / Dyna over here

 

[wormfood]

I don't think a 15B was made, it would be a 15B-F; 4 valves per cylinder. If you don't like the idea of getting an FTE to run, get the F and turbo it, to my knowledge there aren't any internal differences between 15B-F and the factory turbo versions.

There are things internally that are different between the turbo and non-turbo engines, and even a lot of differences between the FT and FTE. Pistons are different between 15B-F, 15B-FT, and 15B-FTE. F and FT use the same connecting rods, but FTE are different, same for the crankshafts and bearings.

The main issue with turboing a 15B-F is that the pistons don't have oil gallerys, the compression ratio is higher, and the injection pump doesn't have boost compensation.

 

[myusername]

There are things internally that are different between the turbo and non-turbo engines, and even a lot of differences between the FT and FTE. Pistons are different between 15B-F, 15B-FT, and 15B-FTE. F and FT use the same connecting rods, but FTE are different, same for the crankshafts and bearings.

The main issue with turboing a 15B-F is that the pistons don't have oil gallerys, the compression ratio is higher, and the injection pump doesn't have boost compensation.

Interesting: there's limited information available online in english and the different 15B versions seem to be spread across different markets, what's your source for the info?

From what I can glean from the FSM, EPC and google image searches, the 15BF and 15BFT have alfin pistons and oil squirters and seem to share similar internals. Some different specs and PN for pistons are different - 15BFT appears to have a gallery for cooling as you mentioned.

I don't see why a 15BF wouldn't hold up to mild boost and fuel, especially when fitted to a passenger vehicle. Considering the setup, they should be far more reliable than all of the indirect injection toyota diesels which are commonly turbocharged by the aftermarket. Many people are running these as everyday drivers without issue, and anecdotal evidence suggests the 15BFT inline pump in stock form can't supply as much fuel as the rotary version. From the FSM the bore diameter and headgasket thickness etc seem to be identical between 15BF/15BFT, so 15BFT pistons+squirters could be theoretically installed in a 15BF? (there are different PN's so I assume they're aimed differently for the gallery type pistons?).

RE: boost compensation, I assume the 15BF rotary pump is similar to the 14BT and 15BFT rotary pumps, and a boost compensator could be added if desired?

Someone posted on the 15B engine swap group with what appears to be a 15BF / 15BFT combo/frankenstein engine. Another struggled to swap 15BF mech pump and front covers onto a 15BFTE block, which suggests the 15BF and 15BFT are far more inter-compatible than the 15BFTE.

My 15BFT appears to have been rebuilt on a replacement block, I haven't put the sump back on after making modifications so I guess I should inspect the bottom of the pistons to check if they have the oil gallery!

 

[wormfood]

I'm mostly basing it on part numbers, but also on various documents I've seen, for example a company that had replacement pistons and had drawings showing that the bowls were all different, and the 15B-F pistons didn't have oil galleries, and the 15B-FTE used a bigger wrist pin. I also remember (don't remember the source unfortunately) that the 15B-FTE had wider bearing journals.

I think you're right that there's more in common between the 15B-F and 15B-FT than the 15B-FT and 15B-FTE, I just wanted to point out that there are differences. I also think you're right that mild turbocharging is probably ok, but again, just sticking a turbo on a 15B-F doesn't make it the same as a 15B-FT.

 

[myusername]

I think you're right that there's more in common between the 15B-F and 15B-FT than the 15B-FT and 15B-FTE, I just wanted to point out that there are differences. I also think you're right that mild turbocharging is probably ok, but again, just sticking a turbo on a 15B-F doesn't make it the same as a 15B-FT.

That's true, but there are also advantages to getting a Dyna 15BF over the Coaster bus (inline pump) 15BFT:

- they're >AUD2k cheaper and readily available locally in Australia with known history, straight from the truck
- buying engine from a wrecker in person allows you to ensure you to check odometer, get all the associated parts that you want, and check running in vehicle before purchase
- they have a rear hump sump, rear pickup, and dipstick in the block not the sump
- they have a bigger intake (15BFT has a tiny 2" intake, fed from a 1.75" outlet on the little turbo)
- anecdotal reports suggest the rotary IP has higher fuel capability from factory
- they usually have the smaller flywheel that fits a landcruiser bellhousing (OEM replacements are very expensive shipped due to weight, second hand hard to source)
- easy and cheap to make a log manifold and buy a turbo, the factory 15BFT turbo (CT12B?) is very small for a 4.1L engine assumedly to get a bus moving from low RPM
- coaster 15BFT all seem to be 24V, I think Dyna 15BF's might be available 12V which saves a lot of effort and cost
- 15BFT imports are always differently equipped depending on what the wrecker hacks off them, they're usually unknown km, damaged from removal/shipping and missing parts
(Many of these may not apply in the USA as they're probably all available only as an import?)

Have you got any info on the difference between the 15BF and 15BFT pistons and/or the difference in compression ratio?

 

[wormfood]

So the problem that I'm running into is that the Toyota part number is always for the piston assembly including the wrist pin and clip, so it's hard to tell what's actually different. For example the 15B-FT Mega Cruiser changed in March 1997 from 13101-58100 to 13101-58101, but I don't know if the piston changed or the wrist pin since I can't ever find them listed separately. There seem to be at least 4 different part numbers for the 15B-FT piston assembly. (13101-58080, 13101-58081, 13101-58100, 13101-58101)

This piston replacement points to part numbers that were used in 15B-FT

but mostly in 15B-F

It would seem I was wrong about compression ratios being different, I guess I just assumed since turbo engines are usually lower compression.

 

[myusername]

So the problem that I'm running into is that the Toyota part number is always for the piston assembly including the wrist pin and clip, so it's hard to tell what's actually different. For example the 15B-FT Mega Cruiser changed in March 1997 from 13101-58100 to 13101-58101, but I don't know if the piston changed or the wrist pin since I can't ever find them listed separately. There seem to be at least 4 different part numbers for the 15B-FT piston assembly. (13101-58080, 13101-58081, 13101-58100, 13101-58101)

The 15BFT in the megacruiser seems to have varied from the Dyna/Coaster versions of the 15BFT. From what I've seen from pictures it looks like they used a rotary IP and a larger turbo (CT26?) than the (CT12B?) on the Coaster bus version. They can be ID'd by the different compressor outlet (both pipes to IC are on the Jap passenger side), and there's a cap on the upper thermostat cover. I wonder if they also had different injectors to suit the rotary IP, and different pistons:

The coster version ID'd by front hump sump, no cap on upper thermostat cover, and the gooseneck compressor outlet:

Then there's the Dyna version, rear hump sump, cap on thermostat cover, smaller compressor outlet facing forwards:

It seems odd that there would be internal variations for the relatively low volume of each different 15BFT configuration.

 

[TriaxialBulls]

Does anyone know why the 15B engines have that weird throttle-like assembly in the intake tract at all? What is it used for? I've worked on lots of diesel engines from different manufacturers and have never really seen anything like that. @myusername any ideas?

 

[myusername]

Does anyone know why the 15B engines have that weird throttle-like assembly in the intake tract at all? What is it used for? I've worked on lots of diesel engines from different manufacturers and have never really seen anything like that. @myusername any ideas?

Mine is a 15BFT - no throttle/butterfly on it. Intake is smaller than the bulky 15BF one and only has the glow screen in it with a smaller ~2" inlet. The accelerator linkage and the shutoff both act directly on the inline IP on my 15BFT.

I have 3B's, which have a throttle/butterfly in the intake, but they use it for controlling the injection pump (drive by cow - there's a leather diaphragm on the injection pump with a tube either side of the intake butterfly). As far as I'm aware the 15BF with a rotary pump is controlled at the IP and people have removed the butterfly from the intake when fitting turbo setups etc.

I've not really looked into it on the 15BF, but I think there may be other Toyota turbo diesels with them, eg 12HT (have heard people call those a shutdown butterfly, but I'm not aware if that's used in conjunction with a shutdown feature at the IP). Perhaps on the 15BF it has something to do with tuning/emissions and/or to smooth on shutdown. Re tuning, a throttle can adjust the air/fuel ratio at low load/RPM, can be used to aid control of EGR equipment on later versions eg 15BFTE, or simply to introduce turbulence.

Apologies for a long post of rambling with no clear answer, I'm just another hobbyist not a diesel professional

 

[TriaxialBulls]

Mine is a 15BFT - no throttle/butterfly on it. Intake is smaller than the bulky 15BF one and only has the glow screen in it with a smaller ~2" inlet. The accelerator linkage and the shutoff both act directly on the inline IP on my 15BFT.

I have 3B's, which have a throttle/butterfly in the intake, but they use it for controlling the injection pump (drive by cow - there's a leather diaphragm on the injection pump with a tube either side of the intake butterfly). As far as I'm aware the 15BF with a rotary pump is controlled at the IP and people have removed the butterfly from the intake when fitting turbo setups etc.

I've not really looked into it on the 15BF, but I think there may be other Toyota turbo diesels with them, eg 12HT (have heard people call those a shutdown butterfly, but I'm not aware if that's used in conjunction with a shutdown feature at the IP). Perhaps on the 15BF it has something to do with tuning/emissions and/or to smooth on shutdown. Re tuning, a throttle can adjust the air/fuel ratio at low load/RPM, can be used to aid control of EGR equipment on later versions eg 15BFTE, or simply to introduce turbulence.

Apologies for a long post of rambling with no clear answer, I'm just another hobbyist not a diesel professional

I found a couple videos of people revving the engine by hand using a linkage on the top of that box:


Although these appear to both be 15B-F's, no turbo. It also might vary based on what kind of pump the engine has (inline vs. rotary). I know the second one had a rotary pump, not sure about the first one though.

It might have something to do with generating vacuum and acting on a diaphragm like you said. But of course this wouldn't work on a turbocharged engine.

 

[myusername]

I found a couple videos of people revving the engine by hand using a linkage on the top of that box:

Although these appear to both be 15B-F's, no turbo. It also might vary based on what kind of pump the engine has (inline vs. rotary). I know the second one had a rotary pump, not sure about the first one though.

It might have something to do with generating vacuum and acting on a diaphragm like you said. But of course this wouldn't work on a turbocharged engine.

No, there's no diaphragm on anything since the 3B/2H in the 1980's AFAIA.

The linkage will have a bell crank down to the IP. On my 15BFT there were vacuum operated idle up etc mounted up on the intake manifold, the cable acted on bellcrank along with the idle up stuff, and then a rod went down to the IP. Mine was missing all the extra stuff, and is rev'd by the linkage up at the intake.

15BFT (assumed Coaster) accelerator linkage in red, shutdown in green:

 

[TriaxialBulls]

No, there's no diaphragm on anything since the 3B/2H in the 1980's AFAIA.

The linkage will have a bell crank down to the IP. On my 15BFT there were vacuum operated idle up etc mounted up on the intake manifold, the cable acted on bellcrank along with the idle up stuff, and then a rod went down to the IP. Mine was missing all the extra stuff, and is rev'd by the linkage up at the intake.

15BFT (assumed Coaster) accelerator linkage in red, shutdown in green:

View attachment 2724331

How do the vacuum mechanisms work properly on a turbocharged engine? Are they hooked up to the vacuum pump?

And if there’s no butterfly valve, what is that box for on yours? Glow screen?

 

[myusername]

How do the vacuum mechanisms work properly on a turbocharged engine? Are they hooked up to the vacuum pump?

And if there’s no butterfly valve, what is that box for on yours? Glow screen?

The 15BF's have a gear driven vacuum pump, it's behind the power steering pump and sits below the IP. A google image search will show this.

AFAIA all of the Toyota diesels have a vac pump on the engine or the alternator for vacuum, whether or not they have a butterfly in the intake.

That rectangular section of the intake is the glow screen as I previously mentioned.

 

[AussieHJCruza]

How do the vacuum mechanisms work properly on a turbocharged engine? Are they hooked up to the vacuum pump?

And if there’s no butterfly valve, what is that box for on yours? Glow screen?

A diesel doesn't produce a vacuum as such, it's throttled on fuel only. The butterfly regulates a pneumatic governor where there is a vacuum line above the butterfly and likewise below it, and the pressure differential pulls on a leather diaphragm which moves the fuel rack to control the amount of fuel.
When the diaphragm on my 2H had a small tear, it would idle at 2k rpm and blew smoke like a Napier Deltic.

When turbocharged, it seems to still work as there must be enough of a pressure differential to make it work, but to my knowledge, Toyota never controlled a factory turbo engine with a pneumatic governor. Most of the commonrail engines, and some others like 2LTE had a butterfly, but this was either to reduce the shake on shutdown or create a small vacuum in the manifold such that the EGR would function.

 

[myusername]

A diesel doesn't produce a vacuum as such, it's throttled on fuel only. The butterfly regulates a pneumatic governor where there is a vacuum line above the butterfly and likewise below it, and the pressure differential pulls on a leather diaphragm which moves the fuel rack to control the amount of fuel.
When the diaphragm on my 2H had a small tear, it would idle at 2k rpm and blew smoke like a Napier Deltic.

When turbocharged, it seems to still work as there must be enough of a pressure differential to make it work, but to my knowledge, Toyota never controlled a factory turbo engine with a pneumatic governor. Most of the commonrail engines, and some others like 2LTE had a butterfly, but this was either to reduce the shake on shutdown or create a small vacuum in the manifold such that the EGR would function.

Warning, thread stealing quasi-intellectual rambling regarding NA vs turbo injection pump diaphragm shiz:

I've experienced the high hot idle with a failed diaphragm, it's scary when you take your foot off the go pedal and the old beast continues forward at >2000RPM!

It's the difference in pressure between the two sides of the butterfly that affects the movement of the diaphragm; with a turbocharger fitted both sides of the butterfly are potentially above atmospheric pressure whereas without a turbo both sides are below atmospheric (vacuum). In NA setup or turbo, the engine side of the butterfly will be at a lower pressure than the other, so the diaphragm will always be pulled in the same direction albeit the response of the diaphragm (diaphragm/rack position vs pedal/butterfly position) will not be the same.

In theory, for any pedal position a turbocharged diesel will have a greater pressure difference across the butterfly, resulting in the diaphragm pulling the rack and the injection pump delivering less fuel. Interestingly, this would suggest adding a turbocharger could make the car feel less responsive to the pedal without adjusting the injection pump. However, the driver may not notice that they're adding more pedal input to achieve RPM at lower pedal inputs (low speed), and the increased sensitivity at greater pedal inputs may make the vehicle feel more responsive when at driving speeds. Butterfly valves are non-linear and are far more responsive at low inputs, which could explain why the old diesels feel responsive to small pedal inputs. By counteracting this, the turbo may actually make the throttle control better for off-roading by making greater pedal/throttle inputs required at low RPM making for a smoother drive on bumpy tracks.

Notably, at full pedal there would be negligible pressure difference across the butterfly, so turbo vs NA would have same maximum fuel without adjusting the pump. In the end, turbo vs non turbo the diaphragm will respond differently through the pedal range, but it will still have the same maximum and minimum rack position. This suggests that the pedal feel will change, but ultimately in a diesel the fuel input governs the RPM, and the min/max won't be changed by simply adding a turbo.

A mod that's been suggested on this forum is installing a higher pressure diaphragm spring; this could result in the pedal response moving closer to the NA setup (at any pedal position, the greater pressure difference across the diaphragm from the turbo would be countered by the stiffer spring). This could make the pedal feel more responsive at lower inputs. Notably, this could also result in the diaphragm/rack travel being reduced; if the butterfly closed position was unable to push the diaphragm/rack to the minimum fuel position, this would result in additional fuel throughout the range of pedal movement until the max fuel position was reached. While this could make the car faster, it's also reducing the range of rack position used which isn't an ideal method of tuning.