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Discussion Starter · #1 ·
Brock/guhl i think it's time for an stage 2+ Ecu flash. Is it a way to modify the Ecu to increase amount of boost at a lower rpm vs almost hitting redline before the 4th boost marker lights up?
 

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It is governed by the characteristics of the compressor map ... and the drive ratio between the crankshaft and the supercharger. In other words, it will require mechanical changes for more boost at lower revs.

From some pics on facebook, I gather that someone *cough* (not me, LOL) just may have been experimenting with this ...

I would urge restraint, because this engine does not have *any* sort of boost pressure regulation including at high revs. (The "blow-off valve" is only intended to give boost pressure someplace to go when the throttle is shut ... not when it is open.) It is completely governed by the characteristics of the compressor map and the drive ratio. Sooner or later there is going to be a limit to what the supercharger can handle, either in terms of mechanical stress or by reaching choked flow conditions. Both the boost pressure, and the mechanical stresses involved, go up with the square of the compressor RPM, so a small drive ratio change makes a big difference ...
 

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If I understand correctly, you have been experimenting with a smaller sprocket on the sc side?
How small can this sprocket go without hurting the life of the engine?
 

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I haven't. Someone has. If it we up to me, I would try one tooth bigger drive and one tooth smaller driven (so that the chain stays the same), and no further, and don't extend the redline past stock if this is done. I'm rather disinclined to blow up expensive stuff.
 

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It is governed by the characteristics of the compressor map ... and the drive ratio between the crankshaft and the supercharger. In other words, it will require mechanical changes for more boost at lower revs.

From some pics on facebook, I gather that someone *cough* (not me, LOL) just may have been experimenting with this ...

I would urge restraint, because this engine does not have *any* sort of boost pressure regulation including at high revs. (The "blow-off valve" is only intended to give boost pressure someplace to go when the throttle is shut ... not when it is open.) It is completely governed by the characteristics of the compressor map and the drive ratio. Sooner or later there is going to be a limit to what the supercharger can handle, either in terms of mechanical stress or by reaching choked flow conditions. Both the boost pressure, and the mechanical stresses involved, go up with the square of the compressor RPM, so a small drive ratio change makes a big difference ...
Well said Gofaster, well said... our 'rule of thumb' is that most modern motorcycles 'engineering window' is approximately 10%. Knowing that we have already pushed that operating window with the H2, by raising the peak operating RPM into the H2R range (which carries limited service intervals), will it be possible to alter the supercharger gears LITTLE enough to prevent catastrophic failure after minimal use?

Brock
 

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I am sitting here on the sidelines with my popcorn, when you say, 'engineering window' is approximately 10%' do you mean max rpm ? Or the speed at which the internal gears, planetary in the supercharger included ? We all know that Busa, and ZX14 engines are way overbuilt and can take massive modifications and produce over 450 bhp safely turbocharged. I can't remember seeing any video's of these bikes ridden hard and then failing while being pushed to their limits. That being said, I am sure someone will find a video to prove me wrong, lol.

Rhody...
 

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Going +1/-1 on the supercharger drive chain will raise supercharger RPM roughly 10%. If you leave redline stock (13,000 rpm) the supercharger RPM will be like what happens with 10% more engine RPM without changing the drive ratio. We know that's been done. It will also raise the torque required to drive the supercharger - and on that drive chain and on the supercharger gears etc - by 21% (because of the squared relationship) and it will - roughly - raise boost pressure by about the same factor.

I've forgotten the numbers but it was previously calculated that the supercharger tip speed wasn't right up against the limits of what has been done before, but 10% more compressor RPM would put it really close to those limits. It is quite possible that in reality, you will not get the boost pressure increase you are expecting at the top end of the RPM range because of the flow conditions inside the supercharger becoming "choked".

It seems rather likely that doing this would shorten the life of the engine, which is why I'm not about to try it. Fatigue strength of materials has a strange relationship to the stress applied. Below a certain stress, something may last literally forever, but then above that threshold there becomes a finite number of cycles until failure, and then a fractional increase in stress results in that number of cycles plummeting by orders of magnitude at a time.

One of this winter's projects is to get my H2 reflashed (mostly so that I can have my quick-shifter back, because I use reverse shift pattern). But, it has to wait until another project (which is waiting for parts) gets off my bench. That project ... is an engine overhaul on my little cbr125 which has been (ahem) leaned on a little bit beyond its stock 12 hp ... which was all well and good, until the dinky little wristpin suffered a fatigue fracture after 37,000 km of being thrashed on. It actually stayed running for another 10 km and got me home ... obviously I didn't know what broke at the time, only that it was making a nasty noise. It's getting put back together with a stronger wristpin (among other things) ...
 

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I am sitting here on the sidelines with my popcorn, when you say, 'engineering window' is approximately 10%' do you mean max rpm ? Or the speed at which the internal gears, planetary in the supercharger included ? We all know that Busa, and ZX14 engines are way overbuilt and can take massive modifications and produce over 450 bhp safely turbocharged. I can't remember seeing any video's of these bikes ridden hard and then failing while being pushed to their limits. That being said, I am sure someone will find a video to prove me wrong, lol.

Rhody...
Rhody,

Correct - RPM kills engines. Most people simply cannot comprehend much additional stress is applied, especially to a reciprocating components, as engine RPM increases.

As an H2 tuner, we have the unique benefit of the factory engineering of the H2R to use as a guideline - it's quite brilliant on Kawasaki's part. Just look at how many ZX-14's and Hayabusa's had to be sacrificed to the engine gods to get where the H2 is now... they were both scattered about all over in their first year. The H2's must have set records for the least warranty claims for a first year machine, and for the power they make - wow?!

Hats off to Kawasaki engineers. And here's to everyone who was able to control their own personal 'greed for speed' in check.

Brock
 

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Hey Brock,
Is there any way to get 271rwh on pump gas, for the street?
Without hurting the engine life?
rapidroy1,

In bolt-on form? Perhaps, but as we extract more power... it must be in 'baby-steps' and properly tested.

If cams are added, I don't think there would be any problem. The real question is: How many guys really want to get into their engine? One problem from the installer and...

Brock
 

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Discussion Starter · #11 · (Edited)
since the h2 intake does not connect directly to the supercharger like the h2r. Is it possible for someone to build a new dual intake with an modified filter box in the same location that it already exist on the h2 that allows a larger filter to be used. That would eliminate the space issue by trying to have the filter in the front like the h2r. That should allow for us to have a dual intake that fits behind our headlight while increasing filter surface area where it's already designed to be housed. Also is it possible to increase air flow by having a dual intake itself regardless of an increase in filter size? if raising super charger boost pressure increases airflow regardless of filter size then I'm assuming increasing intakes from 1 to 2 should have the same effect especially being rammed in at 200+ MPH :smile:
 

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Discussion Starter · #13 ·
Yes I saw someone else mentioned something similar to my above question but never seen a direct reply to that exact question. Since it's not a one year only production bike and newer updated models are being purchased justify someone taking time to fulfill the need/want for a dual air intake solution even if my above suggestion isn't sufficient.
 
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