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Discussion Starter · #1 · (Edited)
Electronic Boost Control

(I have nothing to do with this company, just posting for discussion.)

I have seen a few guys on here installing boost gauges which are cute to watch and maybe might stop you from breaking something but I think are more likely to just let you see the "high score" just before the engine genades.

G-Force II Electronic Boost Controller

Looks like an interesting product. Made for the turbo car guys but from reading the installation instructions it looks like it might be an easy adaptation to the blown bike.

With 6 or 7 presets, you could easily setup a profile to suit street, rain, track as well as a setting for max boost to protect the engine. It would work best for stage 2 or 3 over-driven superchargers for rain or street use but I guess stock setups could benefit too.

Watching a clip of someone's recent H2 run I noticed that their boost gauge showed a 5psi (or more) overrun as they buttoned-off before the blow off valve actuated. I think a separate electronic controller would react faster and would avoid that.

This might not be the right device (doubt it's water resistant) but at the size of a credit card and 18mm thick it might be easy enough to mount in the cockpit and would be a good way to make a high boost bike tamer (or at least closer to stock) on the street.

whatcha think?

Anyone tried something like this?
 

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Only problem is ... the H2's boost pressure is not electronically regulated (aside from some influence in how the blow-off valve operates).

A boost spike in response to shutting the throttle is only there because the throttle is shutting and there is nowhere for the airflow to go ... that boost spike is not getting into the engine - it is completely harmless. Compressor surge is bad for turbochargers but I have yet to hear of a compressor wheel on these engines blowing up for ANY reason. Because the compressor is mechanically driven from the engine, it is not possible to overspeed it (aside from intentionally gearing it up too much) nor is it possible for air pressure stored up in the airbox to back-spin the compressor (which can happen in a turbo application if suddenly there is zero energy being supplied to drive the exhaust turbine).

A correctly sized blow-off valve should not even be capable of regulating boost pressure. Its only purpose is to give just enough flow through a bypass passage to maintain just enough flow through the compressor so that the blades don't stall (we are talking about aerodynamic stalling here, not "stalling" as in stopping an engine accidentally).

The blow-off valve is supposed to be shut at full throttle and stay shut. Bear in mind that with the stock ECU programming, rider-requested full throttle is not actually full throttle ...
 

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^Well said.

The boost gauge on my bike is used to help me see if there is a boost leak. It's not meant for over boosting since as mentioned this is a charger, with a set amount of boost. You wont see any boost creep, and you don't have to worry about wastegate or boost controller failure ;)
 

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Discussion Starter · #4 ·
great reply @GoFaster

I wasn't worried about the compressor wheel, more thinking that getting back on the throttle too fast could cause a rush of pressure.

On/off the throttle is the number one killer of superchargers in high boost drag racing situations too, plenty of funny cars and rails have lifted the blower while "peddling" the throttle.
 

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Discussion Starter · #5 ·
(I need to type faster!)
@Boosted10R it might have been your video that I was remembering seeing the over-run on.

I get the fixed amount of boost, which is why I was wondering if bleeding boost for streetabilty of a higher boost motor made sense... or is controlling your right hand enough?
 

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^Funny cars also run some next level power, and they use a roots style blower, not a centrifugal.

Chris Burns from MC Cycle Works is developing a proper boost controller setup for the h2 for those looking to run extreme boost levels.
 

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On that same note. I notice people are putting different types of BOV's on their bikes and different arrangements. I am wondering who did the specs on the types and spring rates of the BOV's they put on ? If I recall correctly superchargers need 5-7 inches of mercury to open. Some of the big BOV's for superchargers on cars are in the 20-25 inches of mercury spring value. Has anyone spec'ed them out or are people just putting random BOV's on because the inlet adapter fits ?

I mean this respectfully. Just curious how far down the rabbit hole people have looked.

And also technically aren't we turning a bypass valve into a blow off valve when we do this. OEM recirculates the compressed air, that isn't needed because throttle blades are closed, back into the air inlet to be compressed again (bypass valve). We port that off and vent to the outside air and now create a blow off valve. Right ?

NOLA
 

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Discussion Starter · #8 ·
Chris Burns from MC Cycle Works is developing a proper boost controller setup for the h2 for those looking to run extreme boost levels.
I didn't know about that but I'm guessing he will end-up with something that works like the device in the first post.

And also technically aren't we turning a bypass valve into a blow off valve when we do this. OEM recirculates the compressed air, that isn't needed because throttle blades are closed, back into the air inlet to be compressed again (bypass valve). We port that off and vent to the outside air and now create a blow off valve. Right ?
Bypass/blow-off are just terms really. The factory route the air and noise into the airbox mostly for emissions certification more than something technically helpful. In fact, venting pressurised air into the airbox is more likely to cause a lean situation (exaggerated RAM air without equal wheel speed).
 

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Under any circumstances when the blow-off valve is supposed to be on ... i.e. shut throttle deceleration, or part-load operation at higher revs ... you don't need to worry about momentary lean conditions.

If the blow-off valve is open when it isn't supposed to be, you are throwing away the work that it took to compress the air that you are throwing away, which costs BSFC i.e. efficiency i.e. power output. On top of that, returning that air back to the intake stream pre-supercharger will raise IAT. Again, if the blow-off valve is only open when it's supposed to be open (shut throttle) and is shut when it's supposed to be (engine under load), this won't matter.

A bypass valve and a blow-off valve serve the same functions, with the only difference being that a bypass valve recirculates it back to the intake system and a blow-off valve doesn't. OEM applications are always bypass valves, because it is a requirement of the emission control standards that crankcase venting fumes have to go through the engine to be burned, and a blow-off valve will, at least in theory, be capable of venting some of the crankcase vent fumes to atmosphere without being burned, and that is a no-no.
 
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