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9000rpm is attainable on a stock 5.0. Cams and Ported heads and long tubes will allow 9500 which is the limit of the vanos pump. You don't really want to go past this as you don't want to remove vanos the engine will make no power. There is a 6.0 stroker of mine running 9200rpm essentially no limiter. Has titanium rods, billet lightweight pistons, shrick cams, springs, larger valves, ported heads, supersprint long tubes, 880090 thermostat. The only way to make power this high is with a 305 duration camshaft.
You haven't seen any problems with the valvetrain at those RPM? more specifically the lifters?
 

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Thanks for sharing...longer duration cams make sense as they will shift the power range into the higher RPMs...how is the power at the upper limit on the 5.0?, is it usable or does it feel like it plateaus? Just curious.

As for the head porting, I would have expected the heads to be ported to their limits by BMW. How much more room for improving these heads is there when it comes to porting? I’m not questioning you just curious to know more as head porting and camshaft upgrade is something I am familiar with and would like to look into it myself later on.


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Exhaust ports are super restrictive for emissions purposes. Shrick cams work on strokers but not really 5.0L. The gains are had when moving to a larger valve and machining the heads to fit them. 2.5mm larger piston, 10mm longer stroke, each valve is 2mm larger in diameter. All of this stuff is what makes the engine flow really good and take advantage of the cams. But in a 5.0 it is a waste.
 

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Porsche carrera gt with a very and really competition engine runs at 8500 rpm,do you can understand why? And is a porsche not a bmw.porsche won every race,championship an f1 woth tag-porsche.let's go don't joke
 

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Yes the oil system i’d be a little worried about. Dry sump would be great.

But i don’t doubt troys figures or his assertions about the engines. There’s a lot of cool engineering in the s85. I mean **** even 8,250rpm is super high for a production engine.

My lowly Nissan rb26 revved to 8,750rpm for 6 years and nothing exotic there. Plenty of use on track and plenty of dumb moments where it hit the limiter. My newest rb26 with a 2.7l forged stroker crank also revs to 9,000rpm despite having a slightly longer stroke.

As far as the head goes I’m sure the porting is great for the 500hp and 8250rpm it was made for. It makes sense to do some work in conjunction with shorter/fatter intake trumpets and larger valves to get it flowing more air at high rpm in conjunction with longer duration cams.

I did enjoy the post suggesting fuel pumps (plenty of headroom for 20% more power), hollow cams (it has them) and replacing the hydraulic lifters (errm it doesn’t have those).

It does have a great oversqure engine and that’s partly why it revs so freely to begin with.

My first motorbike I bought as a teenager in 1999 was a Honda cbr250rr. It revvd to 19,500rpm! But it’s a bit easier on a small engine where everything is small and light.

The thing is it’s a great engine at 500hp and 8250 rpm. If you want more it’s going to be expensive no matter how you do it.
 

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Porsche carrera gt with a very and really competition engine runs at 8500 rpm,do you can understand why? And is a porsche not a bmw.porsche won every race,championship an f1 woth tag-porsche.let's go don't joke
As I said in my other post. My stock el cheapo Nissan rb26 built in 1989 was running happily to 8750rpm with standard bottom end, some basic oil control mods and longer duration/higher lift cams and some stiffer valve springs. There was no special Porsche magic there and it was still running great when I sold it at which point it was 18 years old and over 100,000kms...
 

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As I said in my other post. My stock el cheapo Nissan rb26 built in 1989 was running happily to 8750rpm with standard bottom end, some basic oil control mods and longer duration/higher lift cams and some stiffer valve springs. There was no special Porsche magic there and it was still running great when I sold it at which point it was 18 years old and over 100,000kms...
Are dfferent materials as magnesium tht r32,33,34,35 doesn'have
 

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Yeah I agree there’s nothing really exotic in them. Cast iron block. Alloy heads. Not even forged pistons. But they have a decent valvetrain and I agree they are a great engine. they sound pretty good at 8500+.

The biggest issue with revving the rb26 that hard is oil control but there’s some fairly simple ways to address it (or do it properly and dry sump it).
 

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I did enjoy the post suggesting fuel pumps (plenty of headroom for 20% more power), hollow cams (it has them) and replacing the hydraulic lifters (errm it doesn’t have those).
@Emfiver
The stock S85 doesn't have hydraulic lifters? Interested in learning more about that...
 

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Yes sorry. My mistake. They are however direct bucket under cam lobe type actuation (which is what I should have said). I just assumed there were shims under the buckets. Looks like they are in fact self adjusting/hydraulic. Either way with that style of actuation higher revs shouldn’t be an issue.. Certainly not 9,000. Given there’s no rocker arms or any of that junk it would be fairly simple to have solid buckets and a set of shims made. Maybe Troy can share his experience with his high reviving engines but I’ve never heard of the lifters being a limitation on rpm in an s85. The style of valve actuation they have is certainly designed for ‘high’ rpm (I guess ‘high’ to most people means over 8,000).
 

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BMW had refinement considerations for this engine, which is damn good actually. Look at how many people ditch the stock exhaust for more noise. Solid lifters make too much racket, and IMO that's really only a solve up to 10k.

The real high RPM applications (beyond 10k RPM), like what you see in F1, use pneumatic assisted valve actuation to ensure the prompt opening and closing of the valve. The design of hydraulic lifters doesn't properly address the issue of valve bounce, stiffer springs help with the inertia of the valve movement at high RPM, but there's nothing to really dampen the movement so you get bounce and float. Float is further exacerbated under the boost conditions (especially high boost like 1.5-2 bar), because the intake side is under pressure, but OP was asking about naturally aspirated RPM limitations, not boosted or stroked. Alot of power is left on the table if the valves are not properly opening and closing compared to if it was properly engineered. Duration and lift start to become moot. This is a real problem at 10k and beyond RPMs. That's not to say the engine didn't hit 9 or 10k RPM. The stiffer springs create a much increased parasitic loss, the cams become much harder to turn. This also increases the torsional forces on the camshaft, so the cross section of the camshaft wall can't be as hollow as they otherwise could be.

Other ways of handling the valve bounce and float is desmodromic design or totally camless designs where the valves are operated electrically or pneumatically. These engine programs were in development in the 2000's but have never made it out of the R&D labs, because electric and hybrid took over once Obama passed the increased fuel efficiency mandates.

As other people have pointed out there are far cheaper ways to make more power, but OP was asking about limitations for a 25% bump in redline. MY assumption was that he wanted reliability, durability, and increased power, not just simply the ability to hit 9 or 10k once. Anyone with a manual can do that easily by downshifting to 2nd at like 70 MPH and dropping the clutch. They might come to regret doing that.
 

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Discussion Starter #39
My life just got easier. I mildly looked at the buckets and assumed they where shim-under, but the ARE hydraulic!

Please understand I am under tight time line to disassemble and diagnose engine as it was purchased on ebay. Assembly will be slow, careful, and CLEAN!

NICE BMW! Will make assembly SO MUCH easier.
 

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Yeah I assumed they were shim under bucket. They look like it. But we were wrong. Agree it simplifies a rebuild. Measuring and getting all the right shims for a 40 valve head(s) would take a while!! It’s bad enough doing 24 on a rb26..
 
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