Question regarding BEW/BRM valves

I have what I believe is a BRM cylinder head that I would like to rebuild for use on a BEW.
I'm aware that the BRM valves are slightly proud even when fully closed, as opposed to the BEW valves which are recessed. Using a straight edge and feeler gauges it seems the valves on the head I have are approx. .330mm proud when closed.
My question is what determines the amount to which the valves are proud? Is it the valves, the seats, or the actual casting??
Could one cut the valve seats to allow the valves to seat further into the head, allowing it to be fitted to a BEW bottom end without risk piston to valve contact.

Thanks in advance.

you can buy cutters that ride the guides for cutting valve reliefs. How deep to go requires a wee bit o' thinking I suspect. BRM pistons would make this all OK...

Douglas

PakProtector said:

you can buy cutters that ride the guides for cutting valve reliefs. How deep to go requires a wee bit o' thinking I suspect. BRM pistons would make this all OK...

Douglas

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Thanks. I'll probably have the work done by a machine shop.

Not looking to go as deep as pistons at this time.

Do keep us in the loop. I would love to do away with the BEW head, with its sunken valves and obstructed ports on the intake side.

Check BRM piston protrusion and head gasket thickness, as well as piston valve relief depth. I would love to put in a set of pistons from an ASZ or ARL to go with a BRM head...

Douglas

Don't the valves go with the pistons? Isn't that why they are the way they are they are on that engine?

The head casting on the BHW is the same as the BRM, but everything else is different. Not sure about the valves, though.

oilhammer said:

Don't the valves go with the pistons? Isn't that why they are the way they are they are on that engine?

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That is pretty much what I'm asking.
If one installled BEW valves in a BRM head would they set into the head when closed?

As previously stated I have a BRM head that I would like to rebuild for use on a BEW block.
Trying to figure out how best to accomplish this without changing pistons, as well.

I would send all this to our machine shop, as they'd know better than I.... Frank would know, too.

Cutting the valve seats is a possible option, however, that is going to change the installed height of the springs. Not sure how much that matters, but it will happen.

I've built Ford engines were setting the installed height of the valve springs is an assumed step in the process, and fairly straightforward when the valve springs are sitting in open air and a valve spring micrometer is easily installed for checking/ setting your spring heights.
I've never set valve spring installed height on a VW head before (no way your getting a micrometer in there), and I have never seen a valve shim in all of the VW heads I have disassembled.

In theory, you would need to add a shim under the spring equal to the amount you removed from the valve seat. Again, not sure how crucial this is on these engines.

I think it would be wasting a perfectly good BRM head, but if you remove about .030” off the valve seats and changed to the shorter BEW valves, you could figure it out. Maybe you should cut valve pockets into the BEW pistons and use the. current pistons and valves.

I think the OP's quest to use the BRM head was to help improve the intake flow potential by not having those webs in the head for the BEW's split port set up.

I'll admit, I don't know how much of a difference that makes. I've driven some really nice, dialed-in BEWs that still had that stock head (they'd never had anything done to the engine proper, never even had the valve cover off), that just were running a different one-piece intake manifold, a Garrett VNT17, and a mild tune and they had gobs of smokeless power. But you look at those webs and think maybe it is taking something away... but the head itself seems far less restrictive than the intake. The intake web looks to cover some 15% of the total volume.

Have to agree with OH...I have a tuned BEW with a GT1749VB and it scoots quite well. It has enough clutch to deserve a set of re-nozzled injectors. It has a BRM intake too... The intake port web does offend me on general principles...LOL

Can a BEW cam sprocket/tone wheel and position sensor attach to a BHW/BRM head?

Douglas

The BHW and BEW use the same hub, sprocket, and CMP. So I'd say yes. The BRM just uses a different hub and maybe the sprocket?

It's more just that the BRM head is the head I have. The BEW is currently in use, so I'm looking to rebuild a head to have it ready to go to cut down on the amount of time the vehicle is offline.
And, while removing the webs in the BEW head may not yield that much performance I doubt it will be a bad thing.

Again, not wanting to go as far as removing pistons, or this thread would be moot and I would just do that and replace them with BRM versions.

Planning on getting a single BEW valve and a single BRM valve just to see how each sits in the head as it is now.

Ok, I answered the question asked, but there is a lot of totally unrelated information than whether a BRM head can be used to do a BEW job. The most direct answer is NO.

The BEW is the only TDI engine I know that the piston tops are flat, which by the way, means a much better swirl chamber effect. All other engines that are TDI's that I know have valve protrusion for the valves and valve recesses in the pistons. So, if you put a BRM/ BHW head onto a BEW block, you are going to crush the valves into the pistons.

And yes, the ONLY difference between the BRM and BHW is the size of the hole in the head gasket to allow for the BHW's larger pistons. Keep in mind, the head gasket thickness is to compensate for the height of the pistons, not the head and the BHW pistons have to fit through the head gasket, therefore, the larger 81.5mm hole instead of the BRM's 80mm (?) hole.

Changing to the BEW valves will do nothing to move the valve seats. The only difference with the BEW valves is that they are .5mm shorter than the BRM/ BHW valves. So, save your time getting another valve from BEW. If you use the BRM valves, the stem height cannot be modified enough by trimming the stems. You will be into the top of the cotters. If you don't get the valve stem height correct, by using a BRM valve, the cam followers are overly compressed.

The other difference with the BEW is that the intake port is split. That is to match with a butterfly on the manifold that closes off the short side of the port. The intent is that in low speed/ low volume air flow that the swirl chamber effect would be improved. I think it's a lot of hokey stuff to make that happen, but it does seem to work, so what the heck.

The pulley hubs are different between the BRM as they don't have split 'finger' for the piston identifier. The BRM have a solid bar, as the BHW/ BEW have the pair of fingers. That cam position sensor does a very cool thing to note which piston it first 'sees' and tells the ECU to fire the next compression stroke in order. That makes the PD motor, properly set up a 'One-Two- GO!' engine.

That is a bit of TMI, but I hope it's clear enough. I've seen the innocent idiot put a BRM head on the BEW block with a very short life, crushed pistons and bent valves. If you change the valve to a recessed valve in a BRM head, you will also have to change the valve to the shorter BEW.

Last thing; except for the valve seats being recessed into the head on the BEW, the head itself for all of the 4 cylinder PD motors is exactly the same casting.

Keystoner, if this is at all confusing, feel free to give me a call or PM me.

Frank, thank you for taking the time to write this. Also, thank you for the offer of communication via PM or phone call, I appreciate it.
I would like to clarify some things as some of the statements made seem contradictory to me.

Franko6 said:

Ok, I answered the question asked, but there is a lot of totally unrelated information than whether a BRM head can be used to do a BEW job. The most direct answer is NO.

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NO as is, or NO, there is no way to make it work??

Franko6 said:

Changing to the BEW valves will do nothing to move the valve seats. The only difference with the BEW valves is that they are .5mm shorter than the BRM/ BHW valves. So, save your time getting another valve from BEW. If you use the BRM valves, the stem height cannot be modified enough by trimming the stems. You will be into the top of the cotters. If you don't get the valve stem height correct, by using a BRM valve, the cam followers are overly compressed.

Click to expand...

Franko6 said:

That is a bit of TMI, but I hope it's clear enough. I've seen the innocent idiot put a BRM head on the BEW block with a very short life, crushed pistons and bent valves. If you change the valve to a recessed valve in a BRM head, you will also have to change the valve to the shorter BEW.

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Here it seems that you are saying "don't waste your time getting BEW valves" and the later say "BEW valves are the only way to make it work."
Maybe I'm missing something.
It seems to me based on what you have written that if someone were to get the BEW valves which are .50mm shorter and the cut the valve seats .50mm and installed the BEW valves with BEW springs then that should in theory work out. Obviously, some measurement would be necessary to ensure you ended up where you wanted to be.

In my experience as long as the valve is where you want it (in this case fully closed, and not protruding from the surface of the cylinder head) and the installed heights of your springs are happy then it should be OK to run.
I would be running the BEW cam and cam sprocket so unless there is a difference in the head casting that disallows that, I don't see an issue there either.

It seems to me that it would be worth it to figure it out, as doing so would give you the head with the open intake ports, and the block with the pistons that create a better swirl chamber effect.

I think the pistons (at least the designers' intent) was that they go WITH the split port design. So there would be no direct advantage using the pistons alone, but as I stated in a previous post, the engine can run fantastic with a conventional one piece manifold. All that split port and flat piston stuff was likely for emissions anyway.

My BEW is totally stock, and it is saddled with a slushbox, but I think it runs pretty good overall. It'd easily run circles around an ALH+01M. What keeps me from asking anything more from it is the awful drive axles that are NLA from Volkswagen. Which means I'm stuck with Chaxles that simply don't last even with only 100hp.

The first comment: In the stock form of the BRM, you cannot use it with the BEW block, which has not valve reliefs in the pistons. Getting the BEW head would make more sense. But that is likely not an option.

Then, you were talking about getting BEW valves to see if that would change the projection of the valve. The valve head diameters are the same size; doesn't matter which engine they come from. You buy any valve for the PD, it will show the same projection. It's the stem length that is different.

Then, if that is what you want to do, cut the seats, install the BEW valves.

I've got the valves in stock. They are good versions. You'll probably want to get a good camshaft to go with your cylinder head. I do that, too. Modified profile, chrome-plated journals, modified cam and rocker bolts that are reusable, modified cam bearings to increase oiling to the cam followers and correct an oiling mistake on the journals.

OK, so assume the short block has relieved pistons. ASZ or ARL for point of discussion...these have lower compression rings and a few other useful features for making a bit more power...

Now can we put a BRM head on a BEW block and EDC16U1 control harness? Sounds like it for sure needs the BEW's cam sprocket holder. Cam position sensor?

Douglas

I wish I could get more of the BEW pistons, especially in oversize, but they never were and likely never will be available. I believe their advantage of not having a valve relief in them improves the swirl chamber effect.

There are companies 'improving' the flow of pistons by 'dimpling'. I can just see the rage coming.. So you know, in some medium duty diesel tests, the reviews are mixed and it depends on load, but as I have said years ago about dimpling intake ports, this is a questionable practice that has a minimal effect when the air speed is supersonic, creating a very small but measurable gain in gasoline engines. I believe it's pointless in a diesel.

But to start with a piston with a flat top is an interest to me with the idea that the disturbance of the flow across the valve reliefs in the BRM piston is no longer there. A flat face on the cylinder head is also likely an improvement; not valve face protrusion. But just like all these turbulence reducing or increasing dimpling ideas, all of them are at best, an incremental 'improvement'.

One particular set of test parameters showed a marked reduction of soot. If that were the case, the later model Common Rail engines could be vastly improved by reduction of the regeneration cycle for the DPF. That whole system, including DEF is the ruination of the future of the diesel engine.

PakProtector, the goal with Keystoner was to avoid the cost of changing pistons. Although that could be one cure for the issue, it's a lot of money to spend compared to the option of fixing the valve relief and replacing valves. I don't have any idea what difference the BEW cam pulley would make. But they two versions (BRM or BHW/ BEW) are interchangable. I wouldn't spend any time worrying about that.

The dimple benefit is to force turbulent flow on marginal Reynolds number flow velocity.

I don't particularly like the sunken valves required for flat/relief-free pistons. What feature does more damage( poor combustion chamber shape due to reliefs, or impeded flow from sunken valves ) I have no idea... ALH with reliefs come in at 19.5:1, BEW w/o reliefs at an even 19:1...so it sure looks like Frank is on to something with the BEW having a better combustion chamber( most of the volume in the donut vs some in the reliefs ).

Douglas

That explains what the R & D guys are trying to do as well as anything. Drag and Turbulent flow . The benefit is 'marginal', as far as I can tell. If it does as some claim and reduce soot, as less need for the DPF and regen would be needed; that would be great. Otherwise, it seems that there are already many things that can be accomplished to improve everything else in the engine, without going way out on a limb with something that may or may not work.

Years ago, I got into the studies showing the length of the unburnt fuel, sprayed into a highly pressurized chamber. The fuel shot 50mm into the chamber before it began to burn. That means raw, unburnt fuel is hitting the piston wall before any fuel is ignited. What good a Reynolds number there? I'm not sure at all.

I'm just waiting for the next 'accidental find'. True Research looks for information, not specific solutions.

The lowered CR for the pistons I'm most interested in ignores the facts of valve relief. The BHW is a 18.25CR. The Crafters are 16.8. More volume for fuel/air, rather than compression becomes the important factor. I did some mechanical/ dynamic compression studies that indicated 18.25 to be a very usable number.