Just bought a S65 longblock to build my stroker

[hellrotm]

Originally Posted by Longboarder

Awesome.

I'd trade my blower in an instant to get a cammed stroker capable of pulling hard to a 9k redline. And track power will be a lot more consistent than a blower car where the ECU pulls a lot if timing based on elevated EGTs, coolant temps, oil temps, etc.

Good luck!

+1

[bigtracing]

op your the man I wish I was doing that instead of an oem build. This makes me want to keep my spare parts and build one over time. I have everything but a rolling assembly in my basement may reconsider selling after I see your build

[coloradoe92m3]

I'm not saying vac heads are necessarily the fix but I do believe if you realize how much air is required at 8k plus ROMs with a 4.6 stroker, I don't know if the manifold trumpets are short and direct enough let alone heads. A custom manifold with shorter velocity stacks would regain high rpm flow and get back character of OEM engine. Stroker would have plenty mid range so trumpets could optimize for high rpm. So manifold and heads in my view won't let you take nearly enough advantage of cams to really bring power back significantly to the right. Probably why BMW went 4.4 l for stroker as anymore and top end parts don't flow adequatly
[

QUOTE=regular guy;15630611]I've looked at the specs of these stage-2 and stage-3 heads a few times. To be honest, I don't get it. Everything on that list of the stage-2 and stage-3 heads (except two items I will discuss separately) are items that any competent engine builder will do anyways. Four of the five engine builders I work with do all of this work as a standard routine and part of the engine build. There is no separate charge from any of them because it is part of the build price.

The two exceptions are unshrouding the valves and porting/polishing. Unshrouding is a bit tricky on this head. There isn't much (if any) room to unshroud the valves. And if you did, it would drop the compression ratio because it would increase the combustion chamber volume. So I'm wondering if this work is really being done, or just a bullet item on the web site.

Porting and polishing. I'd still like to see a head cut apart to know how safe it is. The factory ports are CNC ported/polished. They are very good. I wouldn't trust a hand to port these better than a CNC. So are these hand ported? If they're CNC ported, then what was the method used to profile the original ports, reshape the new ones, and flow bench numbers to back up the improvement. I'm not saying they don't do this and don't make improvements...but I've never seen any hard data posted.



Are there any before/after dyno's or flow bench results for porting work on this head?[/QUOTE]

[Maximusdafarmer]

Awesome man I've seen you post about these plans a few times in the past I think this is very exciting... And not to mention how this thing is going to sound!

[Someone?]

Vac claims to have All Bases covered on the heads=http://store.vacmotorsports.com/vac-...ads-p1817.aspx

[regular guy]

Originally Posted by ibmike

Vac claims to have All Bases covered on the heads=http://store.vacmotorsports.com/vac-...ads-p1817.aspx

Such as?

[Someone?]

Originally Posted by regular guy

Such as?

Everything that had been questioned about making an already well designed head better in every way of coarse=
Unshrouding of Valves
Meticulous Port and Polish Work
Attention to Potential Hot-spot Areas and Chamfering
CC'ed and Chamber Reprofiling as Needed
Proprietary Tweaks to Improve Performance
Everything above is a Flow-Bench and real world tested design

A high performance engine works most efficiently with the broadest powerband when everything is designed to work together.
Stage 3 heads are VAC's pinnacle of R&D and this philosophy.

[regular guy]

Originally Posted by ibmike

Everything that had been questioned about making an already well designed head better in every way of coarse=
Unshrouding of Valves

I have read this page before. In fact I specifically addressed it in post-41.

There may be no room to unshroud these valves. If you do, then it will lower the compression ratio because you are increasing the size of the combustion chamber. The layperson may not have ordered new pistons based on this new combustion chamber size, and probably won't know their compression ratio decreased. Let me bring this to life with some real numbers. Since I don't know how much material is cut while unshrouding the valves, I'll give you a few choices below. These are actual S65 numbers, not pulled from thin air.

Increasing the combustion chamber by 1 CC: Compression Ratio = 11.68
Increasing the combustion chamber by 2 CC: Compression Ratio = 11.46
Increasing the combustion chamber by 3 CC: Compression Ratio = 11.24
Increasing the combustion chamber by 4 CC: Compression Ratio = 11.04
Increasing the combustion chamber by 5 CC: Compression Ratio = 10.84

Meticulous Port and Polish Work

That's a bit vague. I'd like to know how it was done: was the work done by CnC or by hand? My personal opinion is that I wouldn't trust a hand to do this because the factory heads are CnC ported. If by CnC, I'd want to know what equipment was used to profile the port shape before writing the CnC program to change it. I'd also want to know if a head was ever cut apart to see how close water and oil is to the porting work. That's a very critical step and should be required R&D for any shop offering a porting service on these heads. Then I'd want to see the before/after flow bench results along with before/after engine dyno results. I don't think it's unreasonable to expect this data or proof that due diligence has been done and that the cost is worth the benefit.

Attention to Potential Hot-spot Areas and Chamfering

This might not be a bad thing. Although the edges in the combustion chamber aren't very hard, so I'm not really sure this is needed. But let's say they can be improved, so I'd give this one a +1.

CC'ed and Chamber Reprofiling as Needed

Any good engine builder will CC the head as part of their engine building procedure; it's the only way you can calculate the true compression ratio. As for reprofiling the combustion chamber? With the combustion process so tightly controlled, and the engineering work so critical just to make a 12:1 compression engine run on 91 octane, part of me wants to run as far away from this as possible, but the other part of me says "hey, it's been done in the past...what's the harm?" So I'm a bit conflicted on this one. Regardless, you'll be increasing the combustion chamber volume and therefore decreasing the compression ratio. If you still want 12:1 compression ratio or are targeting a specific compression ratio, you'll need to order the pistons after the head work is completed.

Proprietary Tweaks to Improve Performance

What the heck does that mean? I'm not a blind trust kind of guy. If I'm paying for something, I darn sure want to know what it is so I can weight the potential negative consequences of doing it.

Everything above is a Flow-Bench and real world tested design

OK, so where's the data?

A high performance engine works most efficiently with the broadest powerband when everything is designed to work together.
Stage 3 heads are VAC's pinnacle of R&D and this philosophy.

Blah, blah, blah. Marketing 101. I just want to see the data.

Hey, maybe the S65 really does need head work. If it does...then let's see the proof. I really don't think it's too much to expect.

[regular guy]

Originally Posted by ibmike

Everything that had been questioned about making an already well designed head better in every way of coarse=
Unshrouding of Valves
Meticulous Port and Polish Work
Attention to Potential Hot-spot Areas and Chamfering
CC'ed and Chamber Reprofiling as Needed
Proprietary Tweaks to Improve Performance
Everything above is a Flow-Bench and real world tested design

A high performance engine works most efficiently with the broadest powerband when everything is designed to work together.
Stage 3 heads are VAC's pinnacle of R&D and this philosophy.

Here's a photo that will bring some of these topics into better focus. Notice there's very little room to unshroud the valves, and the edges in the combustion chamber aren't very hard to begin with.



In the next photo, you can see the factory intake port that is CnC ported/polished. That's pretty darn good. The exhaust ports are a little harder to see in the lower photo. But they are just as good as the intake ports.

[Someone?]

You know A lot more then me i was just trying to add something that might help, dont kill the messenger, i did go to school for this when i was younger(long ago) and no it wasnt for these new age high tech engines, but i know enough that if your going to add compression through more stroke and bigger cams with more duration you will most likely need more head/intake flow, unless you want the same stroker that everyone that has one has(which is still cool) BUT if you want more then the Average you have to GO ABOVE AVERAGE, thats all im sayn.

Im NOT at all questioning your Knowledge, cause i Know you Know your stuff.

[regular guy]

Originally Posted by ibmike

You know A lot more then me i was just trying to add something that might help, dont kill the messenger, i did go to school for this when i was younger(long ago) and no it wasnt for these new age high tech engines, but i know enough that if your going to add compression through more stroke and bigger cams with more duration you will most likely need more head/intake flow, unless you want the same stroker that everyone that has one has(which is still cool) BUT if you want more then the Average you have to GO ABOVE AVERAGE, thats all im sayn.

Im NOT at all questioning your Knowledge, cause i Know you Know your stuff.

I'm also not disagreeing with you. I think you're sitting on some pretty solid foundation of a tried and true rule of thumb that always seem to go hand in hand. The first time I saw a list of work on a stage-2 S65 head (wasn't from VAC...but another company), I said: "WTF? all of that is part of a normal engine rebuild!" So that seemed like a scam to me. Again, I'm emphasizing that I'm NOT talking about VAC.

But the principles of solid R&D hold true even for VAC. If you're cutting into a head, I want to know where you're cutting and I want to see before/after results. Everything I described above is what my former employer did back in the 1980's (other than the CnC heads). Today we have much greater technology that can map the exact shape and size of the ports and then turn that into a CnC program. I'm hoping the guys doing S65 head work will bring this type of technology to the table...and that's why I want more details about what they're doing.

[BMRLVR]

I spoke to VAC regarding an engine build, the info on what they exactly do to the heads was unclear. The person I spoke to could not give me a hard number on what to expect from the heads from a power standpoint. Looking at the ports of the S65 it is quite clear that there is very little to be gained from porting. The risk with porting the heads is that you may end up hurting the bottom end a lot!

Cams and some good VANOS tuning should gain the top end back that the stroker loses after 7500 but with minimal loss to the bottom end.

The reason regular guy is handling my build is because he works with/is aquatinted with some of the very best engine builders in North America...... If they say don't port the heads, you don't port the heads!

[Brian_VACsales]

The world needs more n/a stroker BMW engines - congrats on the plans!

[Richbot]

Awesome. You are going to have the most desirable M3 in the world when you are done.

[BMRLVR]

Originally Posted by Mike@VAC

The world needs more n/a stroker BMW engines - congrats on the plans!

Originally Posted by Richbot

Awesome. You are going to have the most desirable M3 in the world when you are done.

Thanks guys!

[JRV]

Very cool

Patiently waiting on finished product!

[coloradoe92m3]

If you look at stock dyno, above 7700 the torque falls off relatively quickly . Obviously that has to do with cams mostly but at the same time the OEM intake and heads were built around stock cams. Throw bigger cams and stroke a car, the air flow required above 7500 is huge and a lot more than OEM. The relatively long curved intake trumpets are not conducive to larger amounts of air at high RpMs than stock. Then head perhaps not flowing

Look forward to dyno results. I would get a custom intake manifold with shorter more direct velocity stacks. There is a limit to a heads airflow even with moficatiin .

I think going with cams will take away mud range and not give you anything significant up too due to manifold, trumpets and heads not flowing enough

[Dave07997S]

One thing to consider, I would take a small loss at the low end for more glory at topend as long as I ran a shorter gear. I would go to 4.10s or maybe even 4.45s in a nano second with a stroker build that spun to 9k rpm. Its all in the package of the whole driveline.

Also, does the OEM stroker in the GTS have different cams than the S65B40?

Dave

[phrozen06]

In the long run I predict most E9x M's will be more Stroked then Blown.

[BMRLVR]

Just a note to you all, the engine is currently at a salvage yard in Toronto. I'll be getting it in late June and the build will commence early in 2015....... Completion will hopefully be in time for Bimmerfest 2015.

[Jive]

Originally Posted by BMRLVR

Just a note to you all, the engine is currently at a salvage yard in Toronto. I'll be getting it in late June and the build will commence early in 2015....... Completion will hopefully be in time for Bimmerfest 2015.

Well now this is more of a tease than the gintani TT thread!

[BMRLVR]

Originally Posted by Jive

Well now this is more of a tease than the gintani TT thread!

The difference is that I am upfront on the completion date!