FJ Land speed racer

[racerrad8]

Bike is ready to head out to Bandimere drag strip (or maybe Pueblo) once work, family, and weather aligns! Shooting for Sunday (last day of the season) at Bandimere for their Fall day test.    

I saw on the news last night snow in Denver and a hard freeze this morning.

Were you touched by the drastic change in weather?

Randy - RPM

[fj1289]

Bike is ready to head out to Bandimere drag strip (or maybe Pueblo) once work, family, and weather aligns!  Shooting for Sunday (last day of the season) at Bandimere for their Fall day test.    

I saw on the news last night snow in Denver and a hard freeze this morning.

Were you touched by the drastic change in weather?

Randy - RM

Yep - drove to the airport in a snow storm Monday morning.  Flying back in tomorrow around lunch time and the temps will be in the mid 60's.  We got about 2 inches of snow - pretty good for the first snow of the year.   Got the gardens covered up and the heat lamps going for the chickens.    The next few weeks we'll randomly swing back and forth between nice fall weather and winter weather.   Sunday is supposed to be good weather - no rain and temps in the 60's — great testing weather!

[fj1289]

New track record at the Colorado Mile this year.  The old record was set by a Nissan GT-R in 2015 at 246+ mph.  Shane Stubbs ran 248.0 on a NAKED turbo Busa.   He doesn't make it out of 5th gear.  He is shooting for the fastest speed in the mile for a naked bike - currently 255 mph held my the late Bill Warner aka "Mr 311" (311 mph on a sit-on turbo Hayabusa — second fastest is "only" 269.776!)  They had issues on Friday and took out a couple pistons, overnighted a bunch of parts from their shop and a couple suppliers, built the engine on Saturday, and set the track record on Sunday! 

Here's the video of Shane's record run (and yes - he does "pop up" at 245 mph for air braking!)

https://www.facebook.com/tredwaystubbsracing/videos/465945103791175/

This team is hunting two records in the Mile - 255 mph naked, and 300 with body work!

[Pat Conlon]

Very cool Chris.
Listening to that video reminded me to ask you, have you given any thought to running a vacuum pump for scavenging crankcase blow by?
You can clearly hear the vacuum pump in the video and with the amount of boost Stubbs is pumping thru that 'busa engine it makes perfect sense.
All of the normally aspirated pro stock bikes run vacuum pumps.

[fj1289]

Pat - when we first started I thought we might need to based on the amount of oil I would collect in the catch can on the drag bike engine.   I assumed there would be more issues with the larger nitrous shots.   Turns out, it may have had more to do with the warped cases on the old engine ....

We are keeping the revs down to stock or near stock levels and have not had any issues, so my thought is to let well enough be!  I have not had to empty the catch can at all!  I know a big vacuum pump can be worth a few horsepower, but there are other mods that have to be done with that like reversing some of the oil seals, etc.   It can also effect the oil pump feed on wet sumps too as I understand it.   So, right now where the program is at, I don't really want to open that can of worms unless I really need to.   

I "think" that pump whine on the TreadwayStubbs Busa is the ice water pump for the inter cooler - the tank is mounted in front of the steering stem.   I'll try to find the "walk around" video of the bike.  Impressive.  I love his choice of ECUs - one of the "Pro" versions of the Megasquirt 3

After we hit 215 mph next year, I think a fun science experiment would be to see how close to stock we could keep an FJ and push it to 200 mph in a mile.   I really think it could be done with an EFI conversion using the microsquirt ECU, forged pistons (maybe 1219s so it doesn't require sleeves), a dry nitrous system, upgraded injectors, an exhaust, and maybe cams.  And some XJR rods.  I think a bike with those mods that is well put together, well tuned, and well ridden could pull it off.   I'm really impressed with how well so many of the stock Yamaha parts have held up during this effort.   

[fj1289]

Here is the walk around video of the Tredway Stubbs Busa

https://m.youtube.com/watch?v=yRLVz0q7KLY

[fj1289]

I made it out last Sunday for the final test and tune event for the year at Bandimere.  Good test session overall - two primary goals met: getting the rear wheel speed sensor working and getting a good handle on the nitrous tune (50 HP shot).  Another goal is to start getting some experience on working with the speed based nitrous progression vice the time based progression I've used previously.   

Pretty cold in the morning, so I delay a couple hours to let the track warm up a little (no use trying to tune when simply spinning on a cold track).  There were also a lot of oil downs so we lost a lot of time, but still made 6 runs.   

Run 1 was an engine only run to double check the fueling and make sure everything is working as it should.  AFR's at WOT look perfect and the rear wheel speed sensor is working at speed!  Had pretty good wheel spin about 60' out or so from being a little too aggressive with the throttle (similar to a couple runs at the Colorado Mile this year). Take a quick look at the speeds in first and second gear and set up an initial baseline for the speed based nitrous progression.   

Run 2 is a 50 shot of nitrous starting in 1st gear (1st time I've tried that).  Run seems to go well and picked up 16 mph, but it feels like I'm getting a little wheel hop as the nitrous is coming in.  The AFRs are still rich, so reduce the fuel 10% on the nitrous tune and back off the nitrous progression a little and go out to try again.

Run 3 goes well - pick up another 4 mph, but still getting the wheel hop issue.  Not sure what is causing it - maybe using higher tire pressure than I normally use at the drag strip combined with the track prep.  Also, the rear suspension is a bit softer (from the setup for Colorado Mile) than the last time I had it on the drag strip.  Decide to decrease tire pressure some to see if it helps.  The AFR is still rich so reduce the added fuel for the nitrous by 10% again.   

Run 4 is smooth, but slow - realize I didn't arm the nitrous system.  Frustrated to lose a run this late in the day and head right back into line again.   

Run 5 is delayed for a long time for another oil down.  Finally get to go again.  Carefully go over everything and make a good run.  Still have some wheel hop issues, but the nitrous AFR is finally where we want it!  Scale the nitrous tune up for 100 HP jets and get the jets swapped out and a new bottle in - hurrying to try to make it to the staging lanes before they close!

Run 6 takes off like a shot!  But a lot of wheel hop.  Then it seems the air shifter ran out of air for the 3-4 shift.  Foot shift and keep going - but still getting a lot of wheel hop.  Sucks to end the season on this run - was hoping to put up a good speed number on the 100 HP shot of nitrous, but something about the setup didn't like it.  That's it, we are done for the season at Bandimere.  Hit the scales on the way back to the pits and weight the bike - 520 pounds.  740 with me on board.  Need to knock 20 pounds off of me this year.  Will try to do the same with the bike.  Though, as power comes up, we may need to add some of it back in strategic places - on the bike, not me!

I had a chance to look over the data logs yesterday - very interesting what can hide in there ...

[Pat Conlon]

Thanks for the update Chris. Your wheel hop issue is new. I don't recall that happening last year.
Any thoughts on the cause? Rim? Tire? Track prep?

The very thought of wheel hop at your speeds frightens me.

[fj1289]

Both JMR and Pat have mentioned the wheel hop issue.   Well, this is where data lids may trump the "seat of the pants" impression...

Trying to learn how to use the data logs to find issues during the run.   Adding the VSS (vehicle speed sensor) readout on the rear wheel was a first step.  So figuring out clutch slip vs wheel spin should be easy right?   If RPM goes up but wheel speed doesn't, the clutch is slipping.  If RPM and wheel speed both go up too quickly, then the wheel is spinning.  So, what does that look like?   Well, when it's pretty obvious during the run, it's pretty obvious in the data.   The MeagaLogViewer (MLV) software (used to analyze data from the Megasquirt data log -- or most any other ECU for that matter) will let you see the data channels as it goes thru the log.   It takes a long time to sift through an entire log trying to see anomalies in the data.  Or, MLV can display selected data using a "scatter plot" that graphically  shows the interaction of 3 pieces of info from an entire run in a snap shot.   Very powerful if used correctly - but not much more than an adult Spirograph if you don't chose the right data!

Here's the first run.  Lots of wheel spin in first gear after being a bit aggressive (i.e. ham fisted) once the clutch is out.   Obvious wheel spin - and shows up very well in the plot on the right:



What I thought was wheel hop on the nitrous on the next run looks more like a strange clutch slip.   Rather than a "normal" clutch slip where once it starts to slip it will keep on slipping until you reduce the load in the clutch - I think the lock up arms would overcome the slip as the speed increases.  I also think it was "barely" beginning to slip - so the lock up arms would stop it fairly quickly.   As the speed increases, the lock up is applying more and more force, so although clutch slip will normally get worse in higher gears, the lock up force is increasing even more, so 4th and 5th gear look pretty smith compared to 2nd and 3rd:



Here is another view of the same run:



The VSS divided by RPM field and the RPM divided by VSS field are fields I've defined and can show a couple different things - what gear you are in when everything is working "normally", and the change in engine speed and wheel speed (clutch slip).  I'm sure a more pronounced clutch slip situation would be more obvious in the data, but the "fuzziness" of the line in 2nd and 3rd show the clutch slip and grip issue (if I'm correct in how I'm interpreting the data!)

[fj1289]

Small Improvements continue to be made for next year.  

Received a full set of six centrifugal arms for the lockup clutch - we had been using three previously.  Also have some heavier coil springs to increase the "static" pressure in the clutch.  Increasing the static pressure should eliminate the clutch issues that showed up at the last drag strip test.  I was activating the nitrous at lower RPMs - so I'm assuming the added torque from the nitrous combined with less centrifugal force from the lock up caused the slip-stick issues.  

A couple tuning sessions with plenty of cool down time in between resulted in a smooth, steady idle - even with the very large injectors installed.  

After first of the year it'll be time to start on the race engine!

[Pat Conlon]

After first of the year it'll be time to start on the race engine!

Very cool Chris! Do you think the clutch issues were somehow causing the wheel hop?

What's the game plan on the engine?

[fj1289]

After first of the year it'll be time to start on the race engine!

Very cool Chris! Do you think the clutch issues were somehow causing the wheel hop?

What's the game plan on the engine?

Pat, after reviewing the data logs, I'm pretty sure the issue was a clutch issue vice a wheel hop issue.  I think it was just on the verge of trying to slip.  On a normal clutch, once it starts to slip you have to reduce the load on clutch (roll out of the throttle) to stop the slip.   With the centrifugal lock up - you have increasing clamping force on the clutch as the speed increases.  So as long as the slip isn't so bad the bike quits accelerating, the added clamping force may overcome the slip.   

I'll add some heavier springs in the setup - go from 4 medium and 2 lights to 4 medium and 2 heavy and see how much difference it makes.   I'll also be running 6 lockup arms vice 3 previously.   

Engine plan will focus on the head and cams.  Nothing radical - just incremental changes.  Keep the intake cam and stock valves, go with a larger exhaust cam and oversized exhaust valves.  Budget will determine wether it'll be 1314 or 1349 cc's.  Either way the tops of the pistons will get some additional prep work, opening the chambers up a bit in the head, and opening up the quench area for the nitrous. 

[Mike m]

This is a awesome project.I can't get enough of it

[fj1289]

This is a awesome project.I can't get enough of it

I can't either!

Here's the motivation to get everything sorted this year and really put up a number...

[Country Joe]

This is a awesome project.I can't get enough of it

I can't either!

Here's the motivation to get everything sorted this year and really put up a number...

Oh, that FJ is seriously bonkers, particularly using the original 2 pot front brake caliper. But does anyone here know if anyone had swapped over the later lower fork legs and brakes by 1993? Just wondering....