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Stupid motherfucker
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Discussion Starter · #44 ·
The information that he's provided is incredible. So, so helpful for bike builders. The better an understanding of what materials we're working with makes pushing the envelope of building bikes so much more accessible to us all. My Finnish is pretty crap, but thankfully all the important shit is SI, which is the universal language of SCIENCE. Frame is at the welders, should have some results by the end of the week :D
 

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Stupid motherfucker
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6,826 Posts
Discussion Starter · #45 ·
Just did some checked. NAK3D, he of the world's fastest turbo Street Triple fame, is still running the stock injectors! Apparently they flow 300cc/min which is well within my limits of exploitation. I'm going to check on the fuel pressure on the stock pump and if it's not more than 45psi I'll buy a Walbro 255. Again, that's what NAK3D is running, and if he's doing okay then I should be more than fine!
 

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Stupid motherfucker
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6,826 Posts
Discussion Starter · #49 ·
Ordered my VAG tuning cable and Gilmore pulleys yesterday, and picked the frame up from the welders today. Didn't manage to get any work done on the mounting brackets just yet, but I'll get stuck into that tomorrow after I go watch my mates rugby game. Next step is to mount the supercharger and start measuring for jackshafts and pulley mounts.

Been doing some research on how to fuel for boost on the stock ECU. I'd rather run the stock ECU because it's so well integrated and flexible, and fitting a piggyback power commander is just awkward. The ways I have found are:

1) Leave it as is, and adjust fuelling with the tables. Essentially this removes the autotune/closed loop system. A few guys have done this, not sure how I feel about it.

2) PC3, using a 2bar MAP sensor wired in as a TPS sensor. This reads boost as if it were throttle, and increases fuelling in relation to boost. Bit of a hack, but a few blokes have done it. Keeps the autotune function. Unfortunately this is a piggyback ECU and they're just not my cup of tea.

3) PCV. It can read boost from stock, and the only other supercharged 675 out there uses this. Unfortunately it's hella expensive, and requires more money in order to allow it to autotune. This autotune also doesn't adjust the stock ECU, only the additional trim from the PC, which is just an awkward solution.

4) Apparently, Tuneboy has a method of using the stock ECU and allowing for fuelling with boost. This keeps the autotune function and would be the cleanest install, but it's mega expensive.

Still hunting down options, anyone who knows anything should tell me and I'll PM them something nice. Probably just a picture of a cool bike, but still, it'll be nice.
 

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Stupid motherfucker
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6,826 Posts
Discussion Starter · #51 ·
Thanks for the help Medi, but I know the kind of tuning he'd be doing, and unfortunately it's not to the same level I need. That's the problem here, this is basically new ground and the few people who have tread it, aren't likely to share their secrets. It's going to require a bit of dicking around, unfortunately.
 

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Stupid motherfucker
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6,826 Posts
Discussion Starter · #52 ·
The frame is back from the welders. I'm going to start on the aluminium plates that will tie the charger to the frame this week, and hopefully finish the design for the outrigger shaft on the charger. Once my pulleys arrive, then I can even think about finishing off my belt run and actually starting the outrigger shafts. Who knows?! I'd post pictures, but imgur is being a dick at the moment. I blame my third world internet.
 

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Stupid motherfucker
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Discussion Starter · #53 ·
Shit yeah, I took the day off work to work on the bike. Bought all (hopefully) the aluminium I need for the supercharger mount and appropriate bearing shafts/supports for the cool sum of $50. Fingers crossed I get some good work in today. Will update with pictures tonight/tomorrow.
 

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Stupid motherfucker
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Discussion Starter · #54 ·
I started by making the base plate for the supercharger outrigger. Whoever reckons you can't drill an accurate 90* hole in 6mm thick ally just isn't trying hard enough.





This was done with a battery drill. It'll have a tube welded to it for the bearing that the outrigger runs on, and the same aluminium tube is being used on a plate I made up for the engine outrigger.

I used a proprietary programme called Fukken CAD to design the plenum into the shape of the tank and get an idea of the volume I'm working with.






At least 2250cc of volume, so fuckin' heaps for what I need. It's my understanding that you should aim for 1 1/2 times the volume of your engine, which gives me a little over 1 litre for my ideal plenum size. If any forced induction gurus can let me know whether or not I'm on the money with what I'm putting together, that'd be fantastic.

More work happening tomorrow, stand by for action!
 

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Administrator
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5,263 Posts
Nice work on the hole drilling, love DIY solutions! Alternatively, would one of these hole-saw things have worked?



Also, this is hilarious:

I used a proprietary programme called Fukken CAD to design the plenum into the shape of the tank and get an idea of the volume I'm working with.

And everything about this build:



Really looking forward to this.
 

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Former bike builder
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1,240 Posts
I have never measured how much volume my plenums have.. And never will as common sense get you close enough..


I have thinked always that little too big is better then too small.. As on big plenum volume goes larger then on chargepipes and speed of air slows down.. And when airmass moves slower speed, then it goes more evenly on every part of plenum. And by then more evenly to every cylinder. I want to see that plenum has slow moving pressured airmass and really little flow.. On bikes with carbs we have made lot work to get airflow even... On small boost every plenum will work.. More boost=more problems...

i PM u more later
 

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Stupid motherfucker
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Discussion Starter · #57 ·
Oh hell yeah, a holesaw would have been way better for it. But I didn't have one, and I couldn't be bothered driving the RX8 5 minutes up to the store. I'll chuck it in the mill on Monday to machine out the recess for the other lobe shaft, and make the hole actually round then. I just needed to get the clearance to install it and start measure out everything else.

Thanks Toni, I think it was Biggie Smalls who wrote "Mo boost mo problems". Looking forward to your PM.
 

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Stupid motherfucker
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Discussion Starter · #58 ·
A question for supercharger experts. Do I require a boost reference? The supercharger should (to my mind) be providing me with a constant 5psi, regardless of rev range and throttle position. Therefore, could I not simply increase fuelling by a blanket 33%, and still maintain the correct a/f ratio? Just curious here.
 

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Former bike builder
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1,240 Posts
A question for supercharger experts. Do I require a boost reference? The supercharger should (to my mind) be providing me with a constant 5psi, regardless of rev range and throttle position. Therefore, could I not simply increase fuelling by a blanket 33%, and still maintain the correct a/f ratio? Just curious here.


no you don't need if u have big enough injectors... And 5psi is nothing..
 

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Stupid motherfucker
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Discussion Starter · #60 ·
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