FJ Land speed racer

[Bones]

Randy, Would you have an estimate of what HP that motor would make. The standard FJ's 130hp will get to 150mph, how much more do you think it would need to go an extra 50mph.

[Bill_Rockoff]

Power goes up with the cube of speed.  (Roughly - power required to overcome aero drag does, rolling friction requires something closer to "square of speed" but aero drag is most of your drag at higher speeds.)  To go 200 mph versus 150, you'd need (200/150)^3 times the horsepower - that's 2.37 times as much power.  

Assuming 130 crank hp will get the bike in question to 150 mph, 310 hp ought to do it to get that bike to 200 mph.  That's a bit more than 260 rwhp.

Since the Colorado Mile takes place at 5500' above sea level, a normally aspirated engine would lose about 16.5% of its power due to thinner air.  Boost overcomes that a lot.

Start cleaning up the aero on an FJ (pull the mirrors, put some real thought into getting air past the engine and out the back) and you can make some serious progress.  

Can't wait to read how you do!

PS I am old and my back starts to hurt by the time I am cleaning out carburetor #3, so I am as interested in the MicroSquirt as in the actual top speed reached.

[ribbert]

Power goes up with the cube of speed.  (Roughly - power required to overcome aero drag does, rolling friction requires something closer to "square of speed" but aero drag is most of your drag at higher speeds.)  To go 200 mph versus 150, you'd need (200/150)^3 times the horsepower - that's 2.37 times as much power........  

Bill, I understand the formula, but aren't there plenty of stock bikes that go that fast without that sort of horsepower?

Noel

[Bill_Rockoff]

200 mph?  Not that I've ever read about.  The Suzuki EyeAbuser got about 190 mph pre-restriction, but its advantages over an FJ1100 are partly horsepower (160ish rwhp) and partly aero.  

A 'busa with an FJ's motor in it would run a solid 10 mph faster than the FJ just because of the aero advantages it has.  Its aero is so good that, assuming it would do a repeatable 190 mph with its stock 160 rwhp, you could expect 200 mph out of it with another 30 hp.  

An FJ1100 with a stock Hayabusa's 160 rwhp would run mid-170's, a good 15 mph slower than the Hayabusa.

Much as I love the FJ, particularly for the sort of riding we all seem to do on it, we would do well to remember that it was developed in the early 1980s.  People were just beginning to tape bits of yarn to things and photograph them with a fan blowing to try to see what the air was doing.  The idea that the FJ's fairing should be different so it could top 160 mph instead of just 150 mph would have been nuts 30 years ago.  

Air management through and behind the vehicle is still seeing development.  Nissan developed a LeMans race car last year that is basically a trimaran / pontoon boat, with two huge ducts running between the wheels and cockpit.  

Chris, you have cleared out a lot of space beneath the seat where the battery etc. normally goes.  Is there a good way to route ducting through there?  That would let you route air from the cylinder head / back of the oil cooler out under the seat; there is a big low-pressure area back there, and it would probably help cooling and reduce drag if you could let air IN at the front, and then BACK OUT by the top of the rear wheel.  Aero-wise, this would be the internal equivalent of one of those aero humps on the back of a set of leathers these days.  And it's gotta help cooling to let the hot air out after it passed across the head or through the oil cooler.

[racerrad8]

Bones, I am not going to speculate on HP numbers, the goal is for some dyno time mid-next week to help get some of the final tune sorted out and maybe some HP numbers will come out of that.

The goal is to take smaller steps towards 200 instead of one big swing and if the goal is not reached, we learn a lot on the way and have better info for the next attempt. If we just take one big swing it could all come apart on the first run and then we learned nothing.

I understand the faster you go the harder it is to get there, but hopefully with the solid engine platform, EFI and the magic of nitrious the goal can be obtained.

Bill, we are going to be able just to dump air at the center of the head through the hose Chris is installing as he moved the fairing on the bike and the side scoops are not applicable anymore. There is not enough room, at least right now to plumb anything out the back, but maybe in the future. I also though about possibly leaving the side panels off as the low pressure behind the fairing will allow the air to the cooler/Head a place to escape.

That will have to be one of the back to back runs, to see if it makes a difference.

Randy - RPM

[Pat Conlon]

Chris, I assume with the starter delete you will be using a roller stand to start the beast, what tires are you going to run and what gearing?
Looking at the charts, I see the highest with the 170/60 and 18/38 good for 190mph at 10,500 rpm overun.

[fj1289]

Quick reply for now – I'd really like to dive deeper into this than I've got time now unfortunately.

200 mph in a mile is a pretty tall order - even with a turbo Busa it's not a "given".  I think it took Marc Rittner 3 years to accomplish that goal - of course I think he used over 300 cc's less and two fewer cylinders!  I think he was the first to put a twin over 200 in the mile!

I think it is doable on an FJ - but don't expect it to be easy!  (I also want to do this on something still recognizable as an FJ vice a generic looking LSR bubble wrapped motorcycle...

Bill – I think you are pretty much spot on with the numbers for the Busa, but you are mixing things a bit with the FJ numbers...  The 130 HP for the FJ sounds like "factory crankshaft" numbers whereas the 160 HP sounds like "real world rear wheel" numbers for the Busa.  If I remember correctly, the FJ puts about 105 HP to the rear wheel stock – or maybe 105 was the typical number with a pipe and stock is lower?  Either way, lets use 105 for the stock FJ number (it should be somewhat conservative – i.e. should yield a slightly higher required HP number than what will be needed in the real world).  I also recall the FJ NOT making it to 150 mph in the magazine tests – I remember 144?  146?  148?  Lets call it 145. 
So, plugging into the equation gives (200/145)^3 = 2.62.  Multiply by our 105 HP = 275 HP.  Ouch!  (and pretty much what Bill said above about assuming more than 260 at the rear wheel)  That's a lot! 

But how bad is it?  How much does a modified FJ put out?   Frank Moore's 1350 put down 162 HP using stock sized valves and undisclosed cams.  We might or may not be a little down due to cams - using the Megacyle "drop in" .375 lift, 257 duration (at .040").  Frank was after max mid range torque and reliability – Randy built for power AND reliability.  So, I'm guessing 160 HP is a good rough guess to get us at least in the ball park:  160 x 83.5 (the 16.5% loss of power for altitude Bill mentioned) = 133.6 HP at the rear wheel in Denver, Colorado.  So, a stock bodied FJ would require roughly double (plus a little more!) according to our calculations to go 200 mph.  How good was the tuck of the magazine rider that tested the top speed?  Pretty sure they removed the mirrors when testing the 1100 since they were bar mounted (but I think they left the fairing mounted mirrors on the 1200s – not that its really relevant to this discussion though).   I have cleaned up the rear a bit  - completely removed the entire rear under fender, etc and now have a flat undertail enclosing a thinned tail section.  Will show better pictures once home.   Unfortunately in the name of expediency I've had to add several button head bolts through the undertail to keep things in place.  I've also cut the seat foam away for a lower profile.  I will experiment with cutting the windscreen based on my tuck and how the wind feels coming off it.  The bike is also lowered which will help reduce frontal area – as well as allow more aggressive acceleration early in the run.  So, with the mods we MIGHT get by with less than 275 at the tire (and we might not!)

Lets make a run at this problem from another angle.  Most stock Hayabusa's put around 160 HP to the ground.  That's generally 40 HP short of what's required to get one to run 200 mph in a mile.  That 200 HP is considered the MINIMUM you should entertain for even expecting 200 mph in the mile – and then everything needs to be done well with no adverse factors.  A well known (and accomplished) land speed racer has stated removing the fairing on the Busa cost 14 mph.  That minimum number now jumps up to the 245 HP range.  How does an unfaired Busa compared to a faired FJ with some minor aero tweaks to the tail?  I don't know – but I've got to think it's comparable.  If so, 245 HP from 133 is a lot closer than 275... 

How close are these guesses and assumptions?  I guess we'll start finding out after the dyno on Wednesday and after the runs begin next Friday!

And  like any good modifiers anonymous member – the mods I want to do for next time are mulitiplying!

[fj1289]

Pat - no starter delete.  The starter will go in once the engine gets here.  I'll also be running an alternator on this to help ensure the power hungry EFI stays satisfied!  

18/38 gearing -- I'll start there for my licensing runs.  The trick up my sleeve there is the PM rims -- no cush drive means lots of room for small sprockets.  I just received that 35 I ordered a week or so ago.  (also have 33, 29 and 27 left over from last year's Bonneville preparations).  It's a 180/55 17 tire -- my spreadsheet says 200 right at 11,000 RPM - not wheel slip of course!  I'll have to see how much tire slip we are actually getting.

The mile is as much about acceleration as aero -- even more so the faster you run, so gearing can be critical.  

The limit for a C class license (the one you get as a rookie) is good for 165 mph.  To "license up" you need to make a run between 140 and 164 mph.  The class B license will let you run up to 199 mph.  To license up you need to make a run between 180 and 200 mph.  The class A license limit is 220 mph.  There's more after that, but I won't be concerned with that!  

So the first two runs will be without the nitrous.  First run will be in the neighborhood of 8,000 - 9,000 RPM in 5th.  The second run will see what it will do WOT  without the nitrous.  That run plus the dyno sheet (plus critiques on my riding) will be very valuable info and give some hard numbers to work with)  

Then we'll start with the nitrous runs beginning with a 40 HP shot in 4th and 5th gear, then starting in 3rd gear, then staring in 2nd - and see how the top speed changes.  Then go back a gear or two and increase the nitrous and repeat.  

[fj1289]

I hadn't thought of the side panel idea...I'll bring an extra set to experiment with.  Remove altogether, cut holes, remove portions, etc. 

[fj1289]

Oh - and with reference to the dyno numbers -- I consider them just that - numbers.  The most useful way to use a dyno is to measure changes - trying to keep as many variables as constant as possible.  One of the least useful ways to use them is to compare numbers between them!  Each one is a unique, complex tool with many ways to measure the same thing and come up with a different result. 

The dyno on Wednesday will simply be a tool to help get to the real measure of performance - the time slips! Wether it says 160 or 110, it's just a mark to work from now and to compare to in the future

[Steve_in_Florida]

Thank you very much for taking the time to write this up for us. 

I makes us (me, anyway) feel like being part of something REALLY COOL!

200 MPH!!   

Steve

[Flynt]

Thank you very much for taking the time to write this up for us. 

I makes us (me, anyway) feel like being part of something REALLY COOL!

200 MPH!!   

Steve

+1...  I saw Rittner's Aprilia in progress and felt his excitement.  Loving the chance to experience your project and progress.  Please keep it coming.

Frank

[Bones]

All you need Chris is to get the FJ to rev to 14,000 rpm with the power that BMW is putting out and its in the bag. . Seriously, I hope you reach your goal, and I with surely a few others am watching this thread with great interest. Go the FJ.

https://www.youtube.com/watch?v=gXkeSbt5m9g

[fj1289]

So, what good is an adventure without a little background drama to spice things up?



I thought we had already added enough drama with all the difficulties with the engine build – but no matter how ugly the next problem was, Randy always figured out a way to get it handled and get the bullet out the door and on its way.   

AOG is how we're spelling drama now...AOG (Aircraft On Ground) is the code used for expediting parts when an aircraft is broken and cannot continue to a repair station...
This AOG is a double whammy – right engine has a pretty substantial oil leak, and the right one has a fuel leak inside the engine cowl (think FJ1100 petcock x 1,000!).  And crap! ... the one spare pilot we had is already on the crew because the chief pilot had to fly back commercial yesterday due to all the delays for his own wedding....the nerve of some people scheduling a wedding during the same time as a racing event!  This whole endeavor was already delayed 3 ½ weeks (as a slew of 2 – 3 days slips from the scheduled completion at the repair station in Germany.
So, here I sit in the thriving metropolis known as Goose Bay trying to coordinate the logistical effort to get this bird back in the air and get home!  At least it made it across the North Atlantic! 

Plan A was to divert an aircraft returning to the US that has parts and mechanics on board already!  They were due in today...and are now delayed until late Wednesday.  #()*&!!!!   

Plan B.  The big question mark now is parts – the mechanics are leaving Denver now and won't get here until tomorrow morning.  We haven't been able to source the parts for the oil cooler yet.  Good news is they are hand carrying the fuel line and fittings.  Bad news is there are no motel rooms anywhere for Tuesday night.  If the FBO (Fixed Base Operator – kind of like an old fashioned service station for airplanes) can't arrange with the Canadian military for some space in their barracks, we'll be sleeping on the airplane.  Trying to find the oil cooler and get it out here ASAP – and hopefully depart sometime Tuesday.   Otherwise it looks like Thursday...#()*&!!! Again   

So...worst case now looks like engine install Thursday night...basic tuning during the day on Friday, and registration and tech on Friday afternoon.  Then runs on Saturday and Sunday...



  Now, a plea for assistance...can someone pick up the engine at the shipping company (in NE Denver) and drop it in Franktown (S of Parker) on Monday or Tuesday this week?  I haven't called yet to confirm arrival -- the office hours are M-F 7 am to midnight.  It'll be a heavy (285#) wooden box just over 2' wide, just over 2' tall and 3' long on 1 ½" skids.  It'll save a day if time really gets crushed at the end. 

[fj1289]

   And the mechanic's flight out of Denver just got cnx'd...he's working the changes now...

Luckily I guess we have a day for them ... the parts are still the long lead time...