High flow heads possible approach

In multiple earlier discussions, the stock V12 heads always come up in the conversation (as to how terrible the exhaust side is). I can not afford McLaren 4 valve heads or even Henry's 4 valve conversion heads for $85K, so I have continued to look at another possible way.

The evolution of the Chevy V8 heads of late produce impressive flow rates and HP. I began thinking of how to evolve the standard 2 valve head. Armed with cutaway section photos and photos of the entire motor assembly and disassembly, I began discussions with Trick Flow, Brodix, Arao, M2 Race Systems and Advanced Induction many months ago.

After drawings, measurements and guessing, our first go at it appears to be using the production head and reworking with changes from the combustion chamber, angling (and possibly enlarging) the exhaust valve from the actual valve seat with relocated valve guide and a new D or oval raised port design almost straight out the head. Of course, nothing new here, this is bascially what all the trick heads for American V8's have been doing with some designs canting the valves as much as 23 degrees and making obsene levels of power (we should be so lucky).

The OEM intake valve has approx. 10 degree cant. The OEM exhaust valve has about 2.4 degree cant. By tilting the exhaust valve from the centerline of the valve seat another 8 or so degrees (which then equals the intake valve) and taking the runner almost straight out, it would make the exhaust side flow similarly to the intake side. Of course, porting and larger valves could be done (as in B12 5.7).

These guys are used to grinding, filling, shaping and welding with special
alloy in a furnace welding environment to change lugs, raise port runner by filling the lower area, etc. Then a 4 or 5 axis CNC machining could take care of the new machining requrements after all the welding and grinding.

We have initially chosen the same degree tilt as the intake valve to be able to use the same intake rockers (which serve the more canted intake valve) on the exhaust side. Obviously, the whole lug in the head has to be remade and machined. Also cam timing would need to be corrected which is an issue. But first before shooting it down, we want to modify one or two chambers on a test head and put on the flow machine to see what can be done. It seems logical to me to use a company who is doing this angled valve 'Trick Flow' to check the numbers and take their experience and apply on the V12 head. They feel it will respond significantly and can be twaeked to flow almost as well as a 4 valve head up to 6000 rpm. Above 8,000 rpm the 4 valve kills this design but our motors do not live in that rpm range anyway. Then of course, the headers will be higher on the heads with more curve coming out of the head because of raising the ports. Do not know what the final port design would be (to allow using existing headers with modifications). Only then can we see what all is in the way in the engine compartment.

We also came up with a way to do totally kick arse 4 valve head on a 5 axis CNC machine from aluminum billet whereas the head is one piece and the cam box is a second piece (as on the 6 cyl. M5 motor). Plugs in the middle, intakes and headers totally special, special engine management, etc. There were so many issues, it would be cheaper to buy a used Ferrari V12 or Aston Vantage motor and drop in.

My concept here is to make serious power but at an affordable level and to not reinvent the head from scratch. If this worked out, it would be easy to have a head exchange program to also help keep the cost down.

So, my question to you is have you or do you know of anyone who has been down this path I am on before this to find out where they succeeded of failed? I do not know of anyone who has seriously explored this route with the American hot rod guys.There are many advantages to this route and the proof of concept is not all that pricey.

Would appreciate your comments when you have a moment to respond.

Michael B.

Your old friend having a look at getting the most hp from these heads is exactly the goal. If you will provide an email address, I will send 12 or so photos of an 850 head which has been bandsawn to expose all of the ports. This is huge information for someone like him. I can post them to this thread as well if you like.

After you look at a few, what quickly becomes evident is that the intake port and valve are not bad and can be improved with porting. The exhaust valves and ports are pretty terrible. Of course, porting helps. But still can not come closer to matching the intakes. That is the reason Dinan and others chose to use twin turbos to force the mixture in and out of those 90 degree exhaust ports.

There is truth to the fact that an intake valve limits how much volume of air / fuel can be 'sucked' into the cylinder. However, consider that only when the shape of the intake port / matched to the intake manifold tract and even the tuned horn in the intake manifold are just so, only then can the maximum amount of air / fuel mixture can flow into the cylinder (with as straight a path as possible). Then, the shape of the combustion chamber is important to keep it all moving. Now it is the exhaust valve and exhaust ports turn to move it out and possibly even have the header 'scavenge' a bit of the exhaust residual. Then you have real volumetric efficiency.

Schnitz's idea of getting him some heads would be the plan if he looked at the photos and was able to see how to improve.

I have pursued this with some of the top people in the States and they told me we need to redo the port, to straighten it up by changing the 'tilt' or canting of the valve (such as the intake is canted) and then taking it almost straight out eliminating the 90 degree restriction it now has.

Your engineering friend would likely understand the concept by reading this thread.

I will continue to pursue on this end and will wait to hear where to send the photos.

Thanks for the input , there is much HP to find in the heads that does not now exist. Further, better heads will make even more power when TT'd or SC'd.

This is worth pursuing.

Cheers.

Michael

Thanks Adam.

I will forward the head section whitepapers for you guys to have a look.
Also including the site for a M70 teardown and rebuild which will show Dave what the exterior looks like and the relativity of all the components.

One of the original considerations was the idea of the cost to rework vs. cost of a redone head. Even with all the welding and machining, it appears to be far less than having a head done.

My hope is that relatively inexpensive heads could be reworked and made available on a swap basis (or outright purchase).

Appreciate your spending some time and effort on this. Look forward to hearing back from you.

Regards,

Michael B.

As far as why, I believe our V12 was designed for the E32 750i. A comfortable and large 7 series would want a smooth, quiet, elegant and low rpm torquey motor. That is exactly what these motors are. The simplex chain is one of the first giveaways. Any high revving motor BMW or otherwise uses duplex chains. The 750 used intake manifolds which have the long runner to enhance torque rather than the typical intake with individual butterflies that is a short ram from a large plenum. And most of all, the 'packaging', hence the 90 degree port with low exhaust exit to cast iron lump manifolds. Gentlemen, we have been duped (again).

There was a corporate compromise. Even the CSI's were so smooth you could balance a coin on the intake cover when at idle. Personally, I prefer more of a cammy motor that hates to idle and is anything but smooth.

You are correct that there is not adequate material as stock to port. I am actually not thinking porting. I am exploring changing the exhaust port from 90 degree to more of a straight out higher on the head very similar to the intake. This means furnace aluminum welding to abandon the old lower port with a higher D type design. That is why the valve needs to be rotated from the valve seat to approx. 10 degrees instead of 2 degrees.

The concept is in one operation to remove old valve seat, alum weld the area, add material where the new valve guide will be, fill the lower area that is now port and add material for new lugs for relocated valve rocker, etc.

The second step is a CNC machining operation to add the exhaust valve back at a canted angle with the new straight port and high exit exit. The BMW head casting are of very good quality and consistent.

8Tech pointed out a possible concern with the new valve angle closer to the piston and a flycut may be necessary. Of course, I would prefer not to have to machine the pistons if possible.

Clearly, the water jacket will be breached and a new path will be determined. There are multiple possible solutions to this.

One of the engineers from Trick Flow Technologies is who suggested this approach after doing a little CAD manipulation. Although some knowledgable tuners have tried improvements and had problems, I have been working with head and flow engineers. Originally, I was thinking that they provide new head castings that we could buy at a reasonable price. They can do that but for small quantities, they say mod the existing heads.

Arao Engineering does a neat trick making 4 valve heads for V8's that flow amazingly for the cam in block motor. I proposed they use aluminum billet (as with their other offerings), used their 5 axis CNC to make a two piece head. The bottom is the head with valves. The top is a cam box as with the old 6 cylinder M5. But then you still have the matter of the cam chain for between the two cams per bank and chain to the crank. Since 4 valve heads love to rev, a duplex chain with better tensioner control might be required which will not fit in the existing front housing (more machine work).

Forget the DME and the DK control. All of that has to amended as well. Cam box covers, new intakes, new exhausts, relocation of many parts and pieces around the motor also need to be considered.

Then we discussed using the 4 valve BMW head (on one bank) with mods and making a digital template to allow CNC machining its reverse for the other cylinder bank. That way, so much of the existing BMW parts and hardware could be used. In my opinion, this is the best 4 valve head scenario.

After all of this, you can see why I am going back to trying to use the OEM head as a starting point to make it possible for a number of people to use. Adam is taking all of this to a flow wizard they use who has done work for TWR and other big names.

We are clearly going to need to supply some heads for both the UK bunch to check, make molds of, etc. as well as for the companies here in the States.

I am trying to get my hands on some cracked or damaged heads at favorable pricing for mock ups and trial. I suppose it would be smart to post asking it such existed.

Intakes, heads, cams and headers are usually the first place to gain HP. Since there is no aftermarket heads available, I contend we come up with our own version.

All the E31 V12 guys making the most HP are using a variation of the original heads albeit modified. I am thinking starting with a better and less compromised design.

Please read, need your response on high flow heads

Please provide a bit of input if you would actually be interested in the following. Very real progress has been made and this is to a group effort where your opinion counts. Are you really happy with your V12 as is and have no plans to change? OR

1) I would buy heads that I could swap my old ones for and bolt on approx. 40-50 BHP (including headers). The DME, DK's , etc. would remain as is. Other tweaks would enhance the output number. What is this worth?

2) I want more power output but want simple bolt on's without a major engineering effort. Looking for 65-75 BHP increase and want to swap cores. Other tweaks would enhance the output number. What is this worth to you?

3) I would invest in a Supercharged system or Twin Turbo route to put
me in the 460-470 bhp arena where I do not have to take my motor apart.

4) I am focused on the 8Tech solution close to 600bhp and will pay for it.

5) I want 500+ N/A BHP via a 48 valve M8 style motor using primarily BMW parts & design knowing this will cost more than I paid for the car originally but it must be as well done and at a level similar to the Powerplant 6.0L artwork by Henry.

Please help! We need V12 heads for actual mock-up which will be flow tested and run on test V12. This effort would be by a small but astute Clube31 member group. Depending on your votes and to some degree commitment, this would eventually be rolled out to Roadfly and others to lower cost. This is our Alpha version now.

This whole effort is very serious with solid minds behind it (which does put mine in question, I suppose!).

Thank you for taking the time to give your input.

Firstly, any SC with real boost making real BHP requires the motor coming out and apart. It is not a simple bolt-on unless you are looking at a 400 hp motor. Then add an SC, charge or intercooler, free flowing exhaust and all the brains to run the fuel management and the cost is less. I base my statements on historic fact from actual experience rather than conjecture. THe 850 motors are not bulletproof.

Standard motors do not hold up well to forced induction. If you do not believe me, try it. Running supercharging or Turbos require taking apart and carefully tuning. Forged or billet cranks are a must. Special rods are a must. Removing any sharp edges or corners from the combustion area to avoid detonation is a must.

Dinan did major internal work on their 515 hp TT 850. They even did a 650+hp TT. That conversion was at least $30K back in the '80s. I was at Steve's shop, saw them, did the test drives with Steve around Mountain View and our local shop became a distributor.

One of the big goals on this head rework is to not have to go into the motor so deeply. Without the 6.0L enlargement, TT or SC, the choices are minimal. Here the purpose makes itself apparent. Our idea is to increase volumetric efficiency.

I have done three turbo BMW conversions. The '88 M6L was a Dinan project done in Atlanta by an excellant shop. To put any real amount of boost on the motor requires lower C/R. Dinan used shorter con rods and a thicker head gasket to accomplish. With more boost we were still blowing head gaskets or melting piston crowns. O-ringing the head was the answer and we put huge boost on that motor. Then it melted transmissions and rear ends, melted.

Also did a turbo on early model M3 that also require a motor redo. Finally, an M5 with Dinan turbo conversion. All of these required the motor out and apart and H/D parts installed. Of course, the motor management and fuel requirements were changes as well. These were all expensive conversions and as I pushed for more power and we leaned the fuel curves/ they made more power before they failed.

There is more to be learned and exposed here. As Adam stated, the cams, gears, chains, on and on for a 48 valve motor is frighteningly expensive. A $30K or less 48 valve conversion is simply not going to happen. There will not be a simple answer here.

The V12 heads are actually terrible for power purposes. They are great for a boulevard 7 series toodling about.

Noggie,

I am curious if anyone has put low boost on the M70 motor and at what point the head gaskets blow. As long as the gaskets held it should work.

The ESS site is a good one. The head on the 3.0L flows really well. That is a good part of the reason it makes so much HP.

Sadly, there are no head options with any of these motors. That is one of the reasons that I am exploring all manner of possibilities. There is a racing team near which uses a special type of filler to close up the old ports and remachine new configurations. I am checking most everything.

I do understand your thinking and why.

I am still going through the process with the three main companies here before throwing it the towel.

Thank you for input.

I used to do some work for Elkem Ving of ESI and traveled to Burgen. Where are you located?

Michael

Adam,

It would be interesting to know just how much power could be realized by the porting / polishing, etc.

I will email Faisal and see if he will touch base with Henry to get a feel of what he charges and what he gets as a result. I will ask Faisal to post the results.

I also would like to get specifics from 8Tech as to his knowledge on this.

The only other shop I know that has experience on this is Bavarian Imports in Atlanta. I believe Mike is a Clubber.

Michael