Hot cakes from HP2S to R12S

[peter f]

Hope that everyone knows the "bigger" air inlet ducts saga (aka Boxer burner etc etc)

Good news: www.boxertrix.com :: View topic - Performance modifications from HP2Sport to R1200S

Bad news: No specific info provided > could the HP2S inlets fit to R12S airbox directly (maybe finding the part number for the airboxes in both cases could be the answer) or one needs the Boxerburner related flange glue? (crude).

Ugly news: still I can't figure how the HP2S regulator could cause happiness (not to mention the more air factor)...without remapping (+ serial ECU). Note: Beemer mapping strategy is Alpha-N...I mean that if it was, say, MAF type, then yes it could adjust accordingly, as it is the whole thing makes me rather skeptical.

[congoman]

Hi Peter

Since I am the original poster at Boxertrix I thought I should reply.

FYI the HP2Sport inducts fit to the R1200S air box but my mechanic friend fixed them on using black zip ties.

FYI2 I was told the the fuel regulator is not a passive device e.g. it does not just sit there with a certain sized hole creating a certain pressure. Again this is hearsay from a technician, but I was told the fuel regulator opens further at high revs.

regards

Congoman

ps I'll post pics when I can; the bike is 200 miles away from me at the mo!

[800poundGorilla]

congoman ??

[peter f]

Originally Posted by congoman

Hi Peter

Hi my friend

Max system reports that the air boxes are indeed different with regard their codes (but what this means specifically for the inlet "topology"? I have no idea).

Anyway, when you get the bike back post some pictures please focusing to the airbox-airduct connection. Although I can't understand by what means an OEM Alpha-N could adapt to the new situation....the whole thing is tempting...the 3 items required are rather affordable (around 100E here in Greece).

Great opportunity to get rid of that @$@%@ RabidSomething super gizmo of mine (which doesn't work without L-chips, which cause a HIDEOUS fuel consumption, around 10Lt in town at 1.9 Euro/Lt).

Best, Peter

[congoman]

Hey Peter

I'm not sure what an Alpha N is....

...but my brother has agreed to shoot some photos of the inducts...which will speed things up by some weeks!

Thanks again for the kind help you gave in the past re: rear WP settings - I hope I can be of some assistance in return.

kind regards

congoman

[peter f]

[QUOTE=congoman;5680381]Thanks again for the kind help you gave in the past re: rear WP settings - I hope I can be of some assistance in return. [QUOTE]

Well, that was...er... obligatory from my part (a WP fanatic, he he).

Alpha N means that the ECU can sense Alpha (= TPS angle as measured via a potentiometer) and N (rpm). Based solely on these parameters (and taking corrective input from other sensors like IAT, Knock, temp etc etc) the ECU decides according some predefined strategy (either interactive or not - open/close loop) when to squirt, how long and when to fire the plugs. This set of information is known as a "map" . The strategy has always emissions in mind (or at least emissions in the rpm band/load that the Law/Police can measure in a given road check and/or MOT time). Emission feedback to the ECU is made via some kind of switch (yes= mixture is politically correct, no = do something) known as narrow band L-sensors (the far more expensive wide band L are capable for a true interactive operation).

Thus in similar injection systems the ECU can't sense air quantity : Mass Air Flow (aka MAF) and ... well you understand the puzzle of mine with regard the inlets/regulator WITH no remapping AND no serial ECU around.

[peter f]

So, in a nutshell the Alpha N ECU presuppose that engine's volumetric efficiency is what Dr. Fritz Fon Zupeman decided as the right one > meaning that when you alter some parameters (say free flow exhaust etc etc) ... well I can barely imagine by what means the ECU can compensate and deliver a gazillion of ponies more (or ...er...less, he he).

For sale: super duper gizmo > serial ECU > RapidSomething3 (not working) that can give you at least 67 ponies more (in a parallel universe) at 12345 rpm (ditto). We accept cash, gold, enriched uranium, dinars and/or Pamela's mobile.

[congoman]

www.boxertrix.com :: View topic - Performance modifications from HP2Sport to R1200S

pictures of HP2Sport inducts fitted to R1200S now posted at link above

greetings and kind regards to the folks at Pelican Parts R1100/R1200S Tech Forum

congoman

[congoman]

Hey 800poundGorilla

more Lee Perry than the 'dark continent' I'm afraid

"One step forwards two steps backwards....straight out of Babylon"

congoman

[shreddr]

so if the bigger ducts have more volume, wouldn't that SLOW the air intake speed? the engine is doing the pumping not the airbox. in other words, in order for these to be beneficial, the stock system has to be restrictive in some way, correct?

the stacks i have in my airbox have been shown to increase air speed and therefore flow. i am not so sure about this HP2S bolt on. also, if you were getting more air in, then if you aren't getting more fuel as well you are just making it leaner, verstehen?

Lars?

[jduke]

YouTube - Max Romeo & Tribu Acoustica - One Step Forward (In This Time)

[congoman]

Hey Jduke

Nice one

shreddr

more air + more fuel = bigger bang no ?

...however I have read more than once that the effect of air box pressure is not felt until a certain speed has been reached...

[shreddr]

Originally Posted by congoman

more air + more fuel = bigger bang no ?

the regulator swap was supposed to be the hot tuning trick for the R11S, which i tried on my BCR and i thought it sucked. it felt worse everywhere except wide open. its like a one size fits all solution, when in reality you are probably better off with a "tuned" delivery of more fuel where needed through a Dobeck or RapidBike module.

i don't think it was established that more air is being delivered either, as the air velocity will drop with the larger swept volume. i would love to see some dyno charts, because this one isn't adding up for me, and i have no issues swapping parts if it did!

[peter f]

Originally Posted by shreddr

so if the bigger ducts have more volume, wouldn't that SLOW the air intake speed?

HP2S in airduct diameter is 84mm, R12S is 79,5mm BUT the out diameter (towards the throttle bodies) is the same : 72mm. Meaning that more air comes in and in order to pass from the same hole ... er... moves faster (but has this any effect in the atomization of fuel? God knows). All that assuming that the connecting flange has modified (how?) to allow more air - otherwise we have the classic bottleneck effect.

In any case since fueling is the same (Alpha-N) I expect a tad leaner burning conditions - oxygen surplus (slightly hotter engine : proportionally more CO2 VS CO....meaning more exothermic chemical reactions blah blah blah).

Unless the higher fuel delivery pressure at higher rpm band results to a tad more fuel per squirt cycle.

Moral: appears a no way out situation to me, but exactly because of that I'm going to try it...what difference could make 104 Euros more? (in the Name of Science - obviously). Maybe is the last chance for that @%$@%$ RapidNothing to give me the missing 67 ponies (at 12345 rpm, no less).

He He

[peter f]

PS: At this point I have a "delicate" question for the German Gurus who make the BoxerBurner nuclear airducts > HP2S stuff retails for 76 dollars (~ 50 Euros).

By what means the BoxerBurner absurd price is justified ?

That's the 1M question, he he

[PFFOG]

When you start dealing with air flows on an internal combustion engine it gets VERY tricky, as it is not a steady flow, and in basic terms is stopped 3/4 of the time 9when talking individual port (TB intake, so harmonics, momentum, etc, play as much, if not more of a roll that some restriction.

Anybody that played with 2 strokes and expansion chambers knows all to well, what the proper resonance can do/not do for performance.

I have to agree with Shred, a dyno chart would be interesting.

The changing of the TB to air box tubes was a common change to the old R1100RS bikes, you swapped them out for the GS tubes (at the time about $30/set, to give you more midrange at only a slight expense of Hp at the top end.

[Guest24]

Originally Posted by peter f

HP2S in airduct diameter is 84mm, R12S is 79,5mm BUT the out diameter (towards the throttle bodies) is the same : 72mm. Meaning that more air comes in and in order to pass from the same hole ... er... moves faster (but has this any effect in the atomization of fuel? God knows). All that assuming that the connecting flange has modified (how?) to allow more air - otherwise we have the classic bottleneck effect.

In any case since fueling is the same (Alpha-N) I expect a tad leaner burning conditions - oxygen surplus (slightly hotter engine : proportionally more CO2 VS CO....meaning more exothermic chemical reactions blah blah blah).

Unless the higher fuel delivery pressure at higher rpm band results to a tad more fuel per squirt cycle.

Higher revs on the HP2S dictate the requirement for more air. To achieve lambda=1 the volume must be increased. Can't see how this would improve the R12S for street operations.

[shreddr]

Originally Posted by Nail24

Higher revs on the HP2S dictate the requirement for more air. To achieve lambda=1 the volume must be increased. Can't see how this would improve the R12S for street operations.

I think you may be mistaken what lambda is:

" Lambda (λ) is the ratio of actual AFR to AFR at stoichiometry for a given mixture. Lambda of 1.0 is at stoichiometry, rich mixtures are less than 1.0, and lean mixtures are greater than 1.0.

your comment infers that the HP2S runs richer than an R12S, due to its higher RPM ceiling, which I believe is incorrect.

[Guest24]

No I don't think so, Jeff. Lambda=1 is the 14.7:1 ratio of air to fuel by mass, right. 1 is the perfect mixure for the most bang. The plenum is sized to keep from having a huge change in air pressure during the intake cycle on a cylinder. A larger plenum could cause a significant disruption in pressure.

BTW lambda>1 = richer lambda <1= lean.

The HP2S at higher revs requires more air to achieve lambda=1, therefore a larger plenum is required to prevent the air pressure change during the intake stroke. that's what I see in the larger air ducts and plenum.

[shreddr]

I don't think lambda has anything to do with it. It is more likely for a peak HP benefit. Read this, which was recently posted in another thread by bikermike:

Intake and Exhaust system tuning for BMW Airhead Motorcycles

I love his excellent disclaimer!

"This website is primarily about BMW Airheads. Our Airheads are getting old. None have been made for private purchase since 1995. It is my opinion, based on considerable experience, that you can NOT rely on just any BMW dealership for repair work.....nor for the proper parts and parts numbers. Dealership personnel may well NOT have the proper knowledge nor background. BE CAUTIOUS, CHECK MORE THAN ONE SOURCE FOR INFORMATION, PARTS, AND WORK. BMW themselves sometimes screw-up part numbers and even ship the wrong parts! BMW has also shipped wrong OR poorly made parts now and then!

BMW has been known to publish ERRORS!
Those published errors get compounded when accepted, and re-published, often reworded and wrongly so!...by such
as Clymers, or Haynes!...and you will not find out about any corrections for Clymers and Haynes; unless you ask on
one of the E-mailing Internet LISTS! "