Member Contributer Mohawk Posted May 19, 2015 Author Member Contributer Share Posted May 19, 2015 Dimsport have fixed the missing rev extend, so I'm calling it 120hp :) Link to comment Share on other sites More sharing options...
keef Posted May 19, 2015 Share Posted May 19, 2015 Hell yeah, nice work. Link to comment Share on other sites More sharing options...
Member Contributer HighSideNZ Posted May 20, 2015 Member Contributer Share Posted May 20, 2015 Hey Mohawk Nice looking graph and I do like the stacks. What exactly were the stacks off that you used? Cheers Phil Link to comment Share on other sites More sharing options...
The Phantom Posted May 20, 2015 Share Posted May 20, 2015 You're edging towards 870cc output levels there. Very impressive! Link to comment Share on other sites More sharing options...
Member Contributer HighSideNZ Posted May 20, 2015 Member Contributer Share Posted May 20, 2015 Hey, sorry, I just realised that they are the stock trumpets. Should have looks more closely. Link to comment Share on other sites More sharing options...
Member Contributer gig Posted May 20, 2015 Member Contributer Share Posted May 20, 2015 120hp on a 396lb VFR "WOW" GREAT WORK!!!!!!! Link to comment Share on other sites More sharing options...
Member Contributer zupatun Posted May 20, 2015 Member Contributer Share Posted May 20, 2015 This IS really cool! Link to comment Share on other sites More sharing options...
Member Contributer Mohawk Posted May 21, 2015 Author Member Contributer Share Posted May 21, 2015 Hey, sorry, I just realised that they are the stock trumpets. Should have looks more closely. Yep, originally with the big airbox mod, I cut a standard set off flush with the mushroom lip & then pinned & filled with liquid metal around the mount holes, then filled the rest with car filler. sanded the bottom flush & added double sided sticky tape to locate them before screwing in place. The Yoshi style second set just mount on longer screws with nyloc nuts to keep the clearance at the bottom & one at the top tightened just enough to still allow the screw to turn to locate them. Link to comment Share on other sites More sharing options...
Member Contributer HighSideNZ Posted August 23, 2015 Member Contributer Share Posted August 23, 2015 I've been working on the dual velocity stack scenario, similar to what Mohawk outlines in this post, on my 825 Gen6/5. What I've ended up using for the short stacks are Weber 40mm DCOE 20mm long aluminium ones and them mounted the standard VFR short stacks over the top. Here are some shots of what it all looks like. I've used fixed length aluminium tube spacers to set the height of the secondary stack and positioned the bottom of the VFR stack level with the top of the Weber stack. On first testing, the bike didn't feel that crisp in the mid range so I shortened the spacers by 2mm. What a difference! Mid range well covered and nice even power delivery from 3500 up. Thinking I might take another 1mm off the spacers and see what effect that has. I can always add a washer to bring it all back. Cheers Phil Link to comment Share on other sites More sharing options...
Member Contributer rangemaster Posted August 23, 2015 Member Contributer Share Posted August 23, 2015 Wow. If it works half as good as it looks everybody will be doing it. (Said the guy with carbs...) Link to comment Share on other sites More sharing options...
Member Contributer wagzhp Posted August 23, 2015 Member Contributer Share Posted August 23, 2015 Highside that is some nice looking work there! Link to comment Share on other sites More sharing options...
Member Contributer Cogswell Posted August 23, 2015 Member Contributer Share Posted August 23, 2015 Beautiful work. Link to comment Share on other sites More sharing options...
Member Contributer mello dude Posted August 23, 2015 Member Contributer Share Posted August 23, 2015 Sweet! Very nice... Link to comment Share on other sites More sharing options...
Member Contributer Rush2112 Posted August 23, 2015 Member Contributer Share Posted August 23, 2015 As always... Nice work Phil! I'm very interested in the final spacing/alignment of the primary and secondary VS. Did you go with the 40mm due to your increased displacement or was it related to availability? What are the stock VFR VS 36mm?... 38mm? Any observed increase in the RapidBike fueling adjustments to indicate a measured increase in air charge flow? Link to comment Share on other sites More sharing options...
keef Posted August 24, 2015 Share Posted August 24, 2015 there is some brilliant work happening on here at the moment. I cant big bore a motor, but i can make these stacks, i reckon. And you wont see them ,so when its a bit uglier than phils' work, it wont matter. Big air box and these stacks are going on my list. Link to comment Share on other sites More sharing options...
Member Contributer HighSideNZ Posted August 24, 2015 Member Contributer Share Posted August 24, 2015 Thanks guys. Rush2112, to answer your questions. The airbox base bores, where they fit to the throttle bodies are 40mm diameter, hence why I went that way. I have flowed the throttle bodies, both sides of the butterflies, and matched the throttle bodies to the airbox base and the aluminium trumpets. What I did was made up a dolly to align the trumpets to the airbox base and then pinned the trumpets to the airbox with 3mm spring pins at each end. This way the trumpets are permanently located to the airbox. Calculating the trumpet lengths for my cam timing etc. ended up with the following: Centreline intake port length = 100mm (to step in rubber isolator) Throttle body length = 75mm Airbox base thickness = 6mm So intake runner length to top of airbox base (where trumpets will sit) = 181mm My calcs for a total runner length for 8000 RPM = 251mm And for 10000 RPM = 201mm That would be a trumpet of 70mm for 8000 RPM And a 20mm trumpet for 10000 RPM. The overall length of the short standard VFR trumpets is 52mm So with that length, it all worked out if I could get a 20mm trumpet. All that I could find was the 25mm ones that I ended up with (sorry I miss typed the original post showing 20mm) so it will have pushed the tuned runner RPM down by about 500. I know that was a bit of a long winded explanation but there is some pretty intense calculation goes in to this. Cheers Phil Link to comment Share on other sites More sharing options...
Member Contributer Rush2112 Posted August 24, 2015 Member Contributer Share Posted August 24, 2015 Thanks guys. Rush2112, to answer your questions. The airbox base bores, where they fit to the throttle bodies are 40mm diameter, hence why I went that way. I have flowed the throttle bodies, both sides of the butterflies, and matched the throttle bodies to the airbox base and the aluminium trumpets. What I did was made up a dolly to align the trumpets to the airbox base and then pinned the trumpets to the airbox with 3mm spring pins at each end. This way the trumpets are permanently located to the airbox. Calculating the trumpet lengths for my cam timing etc. ended up with the following: Centreline intake port length = 100mm (to step in rubber isolator) Throttle body length = 75mm Airbox base thickness = 6mm So intake runner length to top of airbox base (where trumpets will sit) = 181mm My calcs for a total runner length for 8000 RPM = 251mm And for 10000 RPM = 201mm That would be a trumpet of 70mm for 8000 RPM And a 20mm trumpet for 10000 RPM. The overall length of the short standard VFR trumpets is 52mm So with that length, it all worked out if I could get a 20mm trumpet. All that I could find was the 25mm ones that I ended up with (sorry I miss typed the original post showing 20mm) so it will have pushed the tuned runner RPM down by about 500. I know that was a bit of a long winded explanation but there is some pretty intense calculation goes in to this. Cheers Phil Many of us love the details and those that don't will skip over it anyway... feel free to be as long winded as you like Cheers Russ Link to comment Share on other sites More sharing options...
Member Contributer HighSideNZ Posted August 29, 2015 Member Contributer Share Posted August 29, 2015 Did some further testing today and took another 1mm off the spacers lowering the top stacks further into the bottom ones. Interesting findings, i must say. By my "butt" dyno the roll on was really smooth but it lacked that bit of a bang. Just not sharp. It also seemed to knock the top end around a bit. So, I've added the 1mm back in and it is back to as before. From this I would have to say that the gap between the 2 stacks is quite critical and probably the only way to obtain the optimum distance would be with quite a bit of dyno time, or lots of road time. Also, going with Mohawks idea of the double nut arrangement, or multiple Nyloc nuts so as you have infinite adjustment is probably the way to go getting the correct spacing, then make the fixed spacers after that. I'll update the post once I have more info. Cheers Phil Link to comment Share on other sites More sharing options...
Member Contributer Mohawk Posted September 5, 2015 Author Member Contributer Share Posted September 5, 2015 Hey Phil, great to see this, somehow missed it the first time around. I must remember to add watch to my own threads ;) Looks good, interesting the difference you got with different settings. So with your minus 2mm where does that place the upper stack relative to the lower one ? Mine are set level, so bottom of upper is level with top rim of the bottom part. The 10mm high mushroom lip, gives a tuned length of 195mm measured with a piece of wire to the lowest edge of a closed intake valve. The 5th gen stacks are all the same size at 60mm, so the low end tuned length is 255mm. You can work out your own 4th reflection wave dynamics here http://www.velocity-of-sound.com/velocity_of_sound/calculator1.htm IIRC std cam timing is 225 degrees, with a tuned length of 235mm for a 4th wave peak at 8600rpm. If you check out my last dyno torque line, you will see that the long & short stack waves work perfectly, with long peak at 8k RPM & short peak at 10k RPM, which gives a totally flat torque curve across that 2000 rpm range. So it does what it's supposed to. Have fun. Link to comment Share on other sites More sharing options...
Member Contributer rangemaster Posted September 5, 2015 Member Contributer Share Posted September 5, 2015 You guys (Mohawk and HighSideNZ) work for NASA? European Space Agency? Love reading your threads, keep it coming. Link to comment Share on other sites More sharing options...
Member Contributer HighSideNZ Posted September 6, 2015 Member Contributer Share Posted September 6, 2015 Hey Chris As the internal diameter of my lower stacks is 40mm I've now got mine set 2mm below the top. Started off with them level and as I mentioned in the earlier post dropped them by 1mm, then 2mm, then 3mm and lastly back to 2mm I'm sure that it is all to do with the area between the 2 stacks and the impedance to flow that it creates. Too large a gap and the flow takes the path of least resistance and instead of air column going via the long path it takes a shortcut between the stacks. I've just put my other airbox back on today so as I can get some better comparisons between the Yoshi style and what I was running previously with Yamaha R6 trumpets. 2 short ones on the front and 2 long ones on the rear. Link to comment Share on other sites More sharing options...
Member Contributer Mohawk Posted September 7, 2015 Author Member Contributer Share Posted September 7, 2015 You guys (Mohawk and HighSideNZ) work for NASA? European Space Agency? Love reading your threads, keep it coming.If we did, we'd have been to Mars & back by now ;) In reality, I'm just an average Joe with a high IQ (who knew ?) from a poor background, that left school at 16. I discovered I have a talent for working stuff out & fixing things. More so if I have an interest. My dad was an Army mechanic when I was very little, so I've worked on vehicles since I was old enough to pass a spanner :) But bikes & aircraft have always been my passion, can't afford a plane, so here we are ! Glad someone enjoys our tinkering. Link to comment Share on other sites More sharing options...
Member Contributer Mohawk Posted September 7, 2015 Author Member Contributer Share Posted September 7, 2015 For anyone having trouble visualising this;- http://www.yoshimura-jp.com/products/engine/images/dual_03.gif Link to comment Share on other sites More sharing options...
Member Contributer Switchblade Posted September 7, 2015 Member Contributer Share Posted September 7, 2015 Nice ^^^^ ... Link to comment Share on other sites More sharing options...
Member Contributer rangemaster Posted September 7, 2015 Member Contributer Share Posted September 7, 2015 2ND on the pic, perfect. Link to comment Share on other sites More sharing options...
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