15BFT Performance Rebuild

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bjowett

bjowett

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Stamford, VT and North Adams, MA
The recently acquired 15BFT engine in my carriage barn needs some freshening. So being the way I am, a stock rebuild just won't do. I'll likely build the long block with the intention of running power in the 225 hp range, give or take 20hp.

The basic plan...

Bore the engine from 108 mm to 109 mm using the factory oversized pistons. This will bring displacement from 4104 cc to 4180 cc. The stock pistons on this engine are of the awesome oil gallery type. The oil jets shoot the oil into the piston gallery/chamber which then circulates through and draws out heat before draining out of the piston. Skirts will receive moly coating or WPC Treatment. Piston tops TBD. Rings will receive WPC Treatment.

The stock rods will be retained as they are far beyond adequate. They will be balanced. These have the 34 mm wrist pins, and while smaller than the 37 mm units used on the FTE, they are pressure fed oil up the center of the rod, which also cools the bushing. As far as I am aware, the FTE rods rely on splash lube for the wrist pins, which is why they needed to be upsized to 37mm. Additionally, the FT rods use a stud and nut to hold the caps on, the FTE has gone to bolts. If anyone has more info on these parts, please chime in. Wrist pins will have the super hard DLC coating applied.

The crankshaft is up the air... balancing with the flywheel and crank pulley is a must. Chamfer the oil holes for the mains and rods.

The oil pump will be blue printed.

An additional oil to air oil cooler will likely be added.

More to come....
 
Lower end, as in pistons, rods, etc? Injection pump? I usually throw myself all in with the research on projects like this, , this one will likely be no different, so I'll let you know what I find out.
 
mohawk said:
Do you know which parts are the same in the 15bf ?
Click to expand...

I think the W04C T is a 3.8 litre, so it may have more in common with the 14b which 3.7litre. Later versions, W04D, were the same cc as the 15B. The Hino engines were used as marine diesels as well.
 
I was meaning 15bf / 15 bft rossco......it does make sence that some hino bits may be common though.
 
The pistons are the main difference between the BF and BFT. While both pistons are oil cooled, only the BFT has the oil gallery type, which helps piston temperatures in critical areas stay even lower. It also has a thicker top ring land. The BF can still take some boost, just not as much as the BFT.

Great technical paper from Mahle about pistons.

https://www.fsb.unizg.hr/miv/MSUI/K... Testing_(Mahle_GmbH)_Vieweg+Teubner-2012.pdf
 
Parts are arriving.

IMG_1920.webp
 
There is a potential choice for a different OEM exhaust valve here. The 1BZ-FPE, which is the lpg/cng version of this engine, utilizes a different exhaust valve. Physically notable differences of the 1BZ valve are a very slightly larger head diameter, a wider seat , a margin that is thicker by about 30%, and a large back cut on the tulip. Being that the valve is twice the price of the regular 15BF Series, I'm wagering, at this point, that it may be an even higher grade of material over the stainless 15BF Valve. CNG/LPG engines tend to have higher requirements of their exhaust valves over even turbo diesels. It's a long shot, but is anyone well versed in Toyota valve materials? 1BZ on the left, BF on the right.

IMG_1929.webp
 
surely there must be a tec department at toyota in japan that can answer these questions or a lab somewhere that can scan them and give you a metal composition ? .. i know my mate has machines that can determine the properties of different stainless steels and stuff
 
True, and they do frequently list "upgrades" or modifications to vehicles and parts in the technical new car features literature. Anyone have access to the Coaster Bus on TIS? Lol!
 
I've looked at a fair few Toyota drawings mainly of chassis and plastic components. Most don't say the material details, likely they say the material conforms to a specific material spec and that's it have to dig deeper to the supplier for actual details
 
I've looked at a fair few Toyota drawings mainly of chassis and plastic components. Most don't say the material details, likely they say the material conforms to a specific material spec and that's it have to dig deeper to the supplier for actual details
 
I've looked at a fair few Toyota drawings mainly of chassis and plastic components. Most don't say the material details, likely they say the material conforms to a specific material spec and that's it have to dig deeper to the supplier for actual details
 
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