Author Topic: Project: Reverse Polarity Twin Turbo (NH750tt)  (Read 263 times)

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Offline KunipshunFit

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Project: Reverse Polarity Twin Turbo (NH750tt)
« on: May 09, 2019, 06:50:53 am »
Hey everyone.  I know my bike is a DOHC, but there is a wealth of knowledge here I'd hope to have access to.

Bike: 1993 Honda Nighthawk 750 with a 1998 engine(no clue why)

The Plan:  A radically customized homologation of a retro modern cafe racer/brat/thing... IDK what to call it. Hence the name.  I intend to borrow the rear suspension from a Harley Davidson (dont oust me yet) softail and locate the shocks under the belly of the bike.  Doing so will free up the room I need to do an underseat install of two tiny turbos (I've done the calculations).  It will be intercooled, and for now run with converted CV carbs, but possibly EFI at some point in the future.  It will not be a fast build, but the end goal is a production quality bike.  100hp at the wheel. And, completion of my most ambitious mechanical project to date (not my first).

I picked up the bike for $500 from my wifes boss, it had been sitting for 3 years.  Hooked up some power to the battery, turned it over for a few second, and she fired to life.  Only on 2 cylinders though, and then 3 but never 4.  It had pod filters that I could pull off by hand, all the plastics were broken, cracked, and barely hanging on with zip ties.  The grips didnt fit, the handle bars were too small for the clutch and brake bracket so they were loose, the headlight was falling off, wires were cut, it was a basket case. 

So I removed everything that was damaged, broken, or useless and was left with what you see below.  It took me a year to come up with a solid plan and do 99% of the research to get started, but now we are there! 

The turbos chosen, after hours of calculations, are the Ecotrons VZ21's.  They're knock off IHI RHB31s.  I'd prefer to use the IHI turbos, but I cant find even one much less two!  At some point in the future they may get swapped out with some high quality Garrett GT12's, but that's way off.

The sketches below show the plan a bit, everything circled in yellow is gonna go away to make room for the rest of the plan.  The blue will be added to the swing arm, and the green is the shocks.

The final plan has been slightly sketched out in the last pic. Also, I know this isn't everyone's cup o tea.
« Last Edit: May 14, 2019, 06:43:16 pm by KunipshunFit »

Offline KunipshunFit

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Re: Project: Reverse Polarity Twin Turbo
« Reply #1 on: May 14, 2019, 06:42:46 pm »
Had a bit of time to do some work today. I'll keep the words short and let the pics talk, We all like pics right?!!  :o

I needed to remove the center stand mount, but wanted to keep the frame rigidity intact, so I welded in a brace in front and tucked close to the engine to give plenty of access to the swingarm.  The brace is 1" x 1" x 0.125" tubing so its plenty strong.  Glad I didnt try it with 0.65, weak sauce.  Then I stood there for an hour staring at the shocks and building the swingarm in my head, and making choo choo turbo noises. lol

Offline Nicklopic

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Re: Project: Reverse Polarity Twin Turbo (NH750tt)
« Reply #2 on: May 14, 2019, 06:57:59 pm »
Following because I like boostie noises and this looks interesting
80' CB650

Offline Dolomite

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Re: Project: Reverse Polarity Twin Turbo (NH750tt)
« Reply #3 on: May 14, 2019, 08:36:04 pm »
Won't those under belly shocks cause some severe clearance issues?

Offline KunipshunFit

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Re: Project: Reverse Polarity Twin Turbo (NH750tt)
« Reply #4 on: May 15, 2019, 08:01:18 am »
Won't those under belly shocks cause some severe clearance issues?

They are not that much lower than some aftermarket exhausts.  I'm investigating ways to tuck them in tighter, but so far non are giving me the angles I want on the shocks for proper function.

Following because I like boostie noises and this looks interesting

Glad to have you on board! 

 

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