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I'm sure many of the local SoCal racers are well familiar with Blackbird Fabworx, we're specializing in performance fabrication, mainly race car builds.
We're building a vintage Honda N600 at our shop and thought this will be of interest to some of the Honda Tech crowd and thus worth sharing in a build log.
We started with this baby, a 1971 N600, which was the model before the CVCC, which was the model before the first Civic (customer photos) -
The lump upfront was originally a motorcycle engine, 600 cc of air cooled menace that left the factory floor pushing out whopping 35 HP.
This ground rippling power was sent down to the ground through some top quality all seasons on 10" wheels!
Owww yeah!
Some basic gutting and the car arrived at our shop looking like this -
The gentleman that owns the car came with the idea for a fun street / autox / track build and was looking into putting a roll bar in the car, maybe with lower door bars just to improve chassis stiffness.
We took a quick look at it and I asked the owner whether he considered a full cage at all, noting that we can do it with lower door bars to keep it streetable, we don't have to gut the doors but the chassis will be MUCH stiffer if we would stitch it along the rockers, some at the door jambs and the windshield frame.
He liked the idea and gave us the Green light for it and a few days later the car looked like this -
We also discussed seats and harnesses and ended up building mounts for a couple of Brides and supplying him with a couple of nice sets of Schroth Hybrid 6 point harnesses (not pictured) -
With our project coming to an end, I was getting curious as to what other plans are in store for the build, with the one thing I was most curious about being the engine. No one goes through building a full cage is going to keep the engine in its earth shattering 35 HP bone stock.
The owner said that there's someone that specializes in building vintage race engine out of these and it sounded like a great way to waste a lot of $$ on something that still wouldn't make any power.
...And so we started talking because it was definitely worth exploring alternative options at that point.
Seeing that we have a Lotus 7 replica in the shop with a Yamaha R1 engine in it, I brought up the option of swapping to a modern bike engine instead of trying to do anything with OEM lump.
Shortly after, this happened -
While our original measurements that we took with the R1 engine showed that will fit in the nose of the car, I had this funny idea of turning it into a mid-engine RWD monstrosity and after going back and forth about it for a few more days we agreed that this was a terrible idea.
One of biggest the technical challenges of such swap is the fact that motorcycle engines are mounted to vehicles that (typically) don't need a reverse gear nor do they have a differential.
There are differentials in the market made to be chain driven (so the bike sprocket is retained) but to compound the problem, our mid engine swap into a micro car means that there is just not enough chain length and unless the chain was residing in a sealed oil bath it will destroy itself rather quickly.
Our solution was to call Quaife and check into their QBA11R unit which in short can be described as a cush-drive-gear-driven-twin-shaft-reverse-box-feeding-into-a-limited-slip-diff.
Geez, what a mouthful... the unit itself arrived from the UK some long 8 weeks later and is pretty freaking awesome -
The part that was a lot less awesome was how this supposedly "Universal" unit was found to be less than universal when we tried to mate it to our R1 engine and had some interference in numerous locations (note cases touching) -
The interference with the 2003 R1 lump could not be resolved without resorting to grinding on the brand new Quaife unit, which is not a good move in my book... at any rate, it was a no-go.
After a number of additional emails to the UK asking which engine was the unit designed for originally, we've learned that the unit was made originally to be paired with a Honda CBR1000RR ("Fireblade" in the UK) of the 998cc variety.
Bingo!
AND, it's a Honda engine!
We decided to make the switch from the R1 to the CBR unit, there's something cool about stuffing a Honda motorcycle engine into a vintage Honda that originally came from the factory with... a Honda motorcycle engine
Once we agreed on the switch, my customer was quick source out the CBR1000RR we needed and I had this pic showing up in my inbox just a few days later -
It's a 2007 Honda CBR1000RR unit, 998 cc displacement with 12.2:1 comp ratio, rated at 172 HP @ 11,250 RPM (red line is just above 12k).
In a 1200-1300 Lbs car, this is going to be a total riot.
So we get it in, put it on the work bench and get the Quaife diff unit back out from the box... Not even close to fitting!
Turned out that some dude at Quaife forgot to mention that this engine will only bolt on if the water pump and clutch slave cyl were relocated.
Grrrrr...
More emails were fired back and forth and eventually we were able to source out the pieces need for relocation.
FINALLY!
I took another look at the beauty shown above and decided it was time to bust out the grinder and do a bit "interior remodeling" -
Yeah, those are the stubs of the rear legs of the cage that we cut off.
Bummer to cut something that we already did, but they are much easier to just redo than trying to work around them throughout the entire process of the build.
Another unfortunate part was that it took so long for the parts to come from the UK that Frank died.
He will be missed.
The good news is that the CBR / Quaife drivetrain fits like magic in the back -
That's it for now.
Been busy with designing all new rear suspension geometry for the car, we're turning it into a double wishbone front and rear.. Sparks will be flying soon.
We're pretty much up to date on the build, and if you guys show interest I'll be happy to keep updating
This car has so many things going for it.
The choice of drivetrain is a big part of it, but not the only piece in the puzzle, we also have wild aero designed for the car, and I mean WILD!
Haha, yeah, the cost of such project is not for the faint of heart.
But at the end of the day, no one goes into such build as a financial investment, we do these things because we love it, that's why
I have my own financial disasters, this one being the most familiar one out there, our shop demo Miata AKA Creampuff -
Finalizing suspension geometry.
Rear is pretty much done, working on finishing touches in the front suspension.
We're using Miata uprights as a base for the suspension design, the configuration itself is a one off custom double wishbone (non-parallel, unequal length) setup.
The packaging is tight, especially in the back where we want as much clearance as possible for under body aero
Rear suspension brackets are getting done and there are some good tricks here.
For the lower arms we are using Miata cam bolts and bushings, so that camber and toe adjustments are both available in the same fashion they're done on the Mazda.
The upper arms have the ability to to adjust at the inner pivot (roll canter / camber curve).
The brackets are all going to become a part of the rear subframe, because while the front can be easily services top and bottom and therefore has no issue being converted into a tube frame, the rear will become much harder to service if welded solid.
Our solution for the rear is to have it all done as a removable subframe, so that any major service or repair work can be done with the removal of the entire rear suspension and drivetrain coming out as a unit.
Still a bunch more that needs to be done, but the rear subframe is getting there.
You can already see the lower drivetrain mounts tacked in and the pickup points for the control arms are all there -
And yesterday we had another "and then this happened" moment
We started working on the front end of the vehicle and after coming to the conclusion that it would simply be easier to remove the entire front end off of the car and add the parts we'll retain back later, out came the grinder and, well, the front fell off.
Which immediately reminded me of one of my favorite comedy skits - "the front fell off" by Clarke and Dawe, enjoy!
"What happened in this case?"
"Well, the front fell off"
"But why did the front fall off?"
"A grinder hit it"
"A grinder? Is that unusual?"
"In a fabrication shop? Chance of a million!"
We've been plugging away at the front section.
Unlike the rear, the frame is welded to the chassis since there are no issues of service-ability.
The front contains very few things - fuel cell (ordering an 8 gallon ATL next week), steering sys and radiator, using a Mishimoto Aluminum Civic rad with a Spal fan.
I'll post more pics shortly!
05-02-2016, 08:13 PM
Honda N600 mid-engine CBR1000RR street / track build @ Blackbird Fabworx
