How often do people drive above 7k RPMs on the streets?

only the finns: Displacement: 1,820 litres per cylinder

We can test the pump and show the results, but there is no way for us to test the two parts together. We can show the results from the pump testing, but that is not a fair representation of our parts. I will get testing papers put together so we can release them with the customer results.

Not sure what you mean by done? The heads aren't a limitation at those HP levels.

For OEM heads they're damn good. I mean maybe Ferrari has better V8 heads now with the Italia? How many guys do you see posting headwork for the S65 or S85? Early on back in the day when a certain guy was talking about the stroker motors being the be all end all for performance on the S65 he went to have people look at his heads and the conclusion was it was not worth it.


With a boosted motor or for someone eeking out every last HP I'm sure there is something to gain. There has to be. It just won't be as much as domestic heads because their motors aren't 100 hp per liter to begin with.

The new set of BMW springs seems to be stronger. I'll check on my springs I don't even know what I'm running.

Asked me if it's sleeved, simple as that. No big secret.

Of course the S65 heads are good. What is supporting the NA power as is?

I can't ported it but the heads aren't the limitation yet and I don't know if they ever will be for me. There isn't enough to gain right now to even bother with it.

That's very interesting. Perhaps it has something to do with a lot of Americans being what I call Brand whores. So they'll pay whatever it takes to look like they are the best, or richest whatever. Truthfully, I don't know A41.8, but I have seen his work in person a few times and his stuff is nice. I do actually think he charges a little more than he should contrary to how my above post probably sounded, but who am I to determine what his time is worth. That would be a pretty big jerk move. His work is solid, and people are willing to pay for it. So realistically why would he charge less?

I can't speak for 1.8t on repairs on the system or choice in mufflers, only on what my buddy does. He warranties his work, and will make changes if something isn't right at no cost. He just asks people what they want sound wise from their exhaust and he goes from there. Mufflers have different packing materials, shapes, types of chambers, and sizes, they all effect how the exhaust sounds, and to an extent performs. My friend has no scientific way of doing this, other than using his experience. You do something long enough, you just know what works.

I don't see how it would be rare to ask stock block and mean something entirely different than the question. It's not an aftermarket block, it's the block that came with the car. If someone wants details on if the INTERNALS are built then ask that question. I usually ask built motor or not, simple.

You ask if it's sleeved or bored? Good, then you'll get an answer to that question. As the answer to the question is it an OEM block is that yep, it's an OEM block manufactured by BMW last time I checked.

No porting and think I'm still on the stock valves too. Blessing of having an awesome NA motor as the basis.

BMW themselves took it to 10k in testing. VAC destroked one recently with a 3.5 liter crank and who knows how high they are revving but it's more than any N54 ever will.

As I stated a while ago. It's no contest and this helps the S65 make up for its displacement.

Honest question here, but what research and development do you do and fine tuning on these "custom" setups, how many hours do you spend tweaking the sound and changing things and starting from scratch?

How do you know when building a one off exhaust what will provide the best sound on each specific car? What materials do you use, do you have pictures of your welds, do you use generic mufflers and resonators?

What is your shop?

You forgot to mention you aren't a Chinese slave. Just to add to this, piping isn't as cheap as people think. Especially when you start having to add bends into it. My buddy makes a lot of custom exhausts. He pretty much gets this reaction from everybody, then they usually say they have a guy who will do it for less. Some how they always end up calling back month or two later, or just never get an exhaust. I'm sure you get that. You gotta pay to play. If you want top notch quality the price will obviously reflect it. I have no problem of people buying cheap stuff, but don't pretend they are the best. I have raceland dp's on my 335i. I know they are crap. I don't need to convince anyone otherwise.

Exactly. R:S ratio, piston speed are not limiting factors. They just give you a picture of what the engine parts have to endure. You can build an engine to take anything. Better R:S ratio, lower piston speed (through either shorter stroke or longer rod), longer rods (less harsh rod angles) all give the engine components a mechanical advantage on the stresses it has to take (some at a cost of hp through loss of leverage). Some conditions are just more ideal than others.

42 m/s is retardedly fast. I'll bet those engines have long rods and very strong materials.

Strength of the materials used is the end all be all. But holding that and everything else the same, R:S ratio is very important. It affects the angle that the rod will get as it moves along the crank. The greater the angle, the more side wall force on the cylinder wall and bending moment on the rod. The greater the length of the rod, the less side wall force on the cylinder and bending moment on the rod.

The mean piston speed is 20.9 m/s or 4115 ft/min

Um no because I can differentiate between a block, and pistons, and rods, and crank, and heads, and bearings, etc. That's also why they have shortblocks, longblocks, etc.

This thread has actually been a blessing in disguise. We are going to be building a S65 high revving race engine for the new shop race car. I actually was going to start putting information together so my machinist and I could sit down and figure out what it's ultimate rev limit will be with hydraulic lifters, and with custom mechanical tappet/shim lifters would be. We're hoping to hit 10k+

but, I'm getting off topic.

Stock bore is 84mm. Stroke is 89.6mm. Stock rod length is 145mm.

I have calculations for piston speed at all rpm too. It was a fun little math exercise. At 7000rpm, the pistons get up to 34.37 m/s! That's pretty fast.

Problem with mean piston speed is that when do you think you are most likely to have failure? Max speed or mean speed? After a little searching I found that the s65 rod length is 140.7mm. This is shorter than the n54 rods. But with the shorter stroke, the rod/stroke ratio is 1.87. This is much better than the n54 for high revving. The n54 comes out to 1.62. Rod/stroke ratio is a great indicator of whether or not is capable of revving high.

Max piston speed for s65 is approx. 34.22 m/s or 6736 ft/min. Mean piston speed is only 4145 ft/min. That's a difference of 2591 ft/min.

Nobody said OEM pistons and rods...

The S85 has made 1800 or so HP I believe.

How so? It's an OEM block and I have OEM heads. What is the problem?