BRM bottom end with BEW engine build?

2footbraker

Veteran Member
Joined
Sep 6, 2005
Location
Ontario, Canada
TDI
06 Jetta, 01 Golf
Is there any advantage in using a BRM bottom end with a BEW engine? I am asking because I am doing a BEW build and I have a BRM shortblock in my possesion.

I know the oil pump has a higher output on the BRM. Would the BRM piston valve cutouts lower the CR appreciably? Any other differences in the crank or rods?

Would the BEW ECU mate with the BRM crank sensor?

Is it there any point as I am planning on a 250 hp ceiling as my goal?
 

Franko6

Vendor , w/Business number
Joined
May 7, 2005
Location
Sw Missouri
TDI
Jetta, 99, Silver`
The BEW cylinder head has recessing valves; the BRM piston has valve reliefs, which inefficiently reduces the compression ratio. I don't think you are going to find any aftermarket BEW pistons, as we have tried. Unavailable everywhere we have looked. The lack of valve recesses in the BEW pistons are actually an advantage, as there is less disruption of the swirl chamber.

The bigger problem is those who would think that a PD motor could reliably perform at 250hp. We have seen stock cylinder heads crack into the intake port and all the way to the injector seat. Lots of heads crack from the injector hole to the intake valve seat.

The head is extremely close in the method that the valves are built, leading to short valve guides, and valve springs that have an OVAL PROFILE cross-section, in order to prevent spring bind. There is little room for heat dissipation, in my opinion.

Also, I would worry that the pickup design between the BRM and BEW cam position sensor, being different, you would want to keep the BEW cam sprocket to match a BEW ECU. The position of the cam sensor is identical, but the pickup fingers are not.

If you want, we have BRM cylinder heads that we have built that would 'fit'. We also improve the oiling of the cam bearings with our mods and better yet, have a custom-built cam alignment bar that corrects the problem created by VAG when they manufactured the head. The VAG manufacturing method of align-boring the cam journals was to assemble only the cam caps onto the cylinder head. When the injector rocker shafts are installed, the cam caps are warped out-of-shape, causing immediate wear, particularly on the two end cap bearing sets. The end cap's rocker shaft bolts are offset in the cam cap, torquing the cap out-of-line. We correct the misalignment by installing the rocker shaft to load, then boring the cam journals true.

We found an 'upgrade' we have recommended for not only the BEW, but also the ALH, as the difference between the BRM oil pump is not the pump itself, but the chain length, oil pump sprocket and the tensioner. We stock those upgrade items. The difference is the BRM oil pump sprocket has 27 teeth instead of ALH/ BEW, which has 33 teeth, making about a 22% increase in oil pump speed. This increases volume at idle, which is a very good idea. As VW thought it was good for the BRM, we think is also good for other engines such as the ALH, ASV and BEW.

Otherwise, the BEW crank is not the same in the BRM, as the BRM has a rear main seal mounted crank position sensor, where the BEW has a Hall's sensor against a crankshaft reluctor wheel as the older ALH engine has. I don't recall if the BRM crank is drilled for the reluctor wheel, but you would have to mount one. Between the two formats, I think the older ALH/BEW crank sensor design is going to be the more 'user-friendly' approach. Look at the rear of the BRM block compared to the BEW. You don't have a place to install the crank position sensor connector in the BEW block.

Other than that... NO PROBLEMO!
 
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2footbraker

Veteran Member
Joined
Sep 6, 2005
Location
Ontario, Canada
TDI
06 Jetta, 01 Golf
Thanks for the info. I saw some Nural BEW pistons on Rockauto.

I think I will actually be aiming for around 200 hp. I think I will keep the BEW bottom end and BEW pistons and swap in the BRM oil pump gear and chain.
 

2footbraker

Veteran Member
Joined
Sep 6, 2005
Location
Ontario, Canada
TDI
06 Jetta, 01 Golf
Hey Frank, do you think the PD engines would benefit in an external air to oil cooler to keep the cylinderhead temps from spiking?
 
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