Topic: Turbo Charged CB550 Landspeed Attempt

[BomberMann650]

That first picture is awesome!

Indeed! It's calendar-worthy!

Thats on you guys to nominate and vote.

I already got one for my wall that means much more.
After a $260 donation to the wendover museum effort, I hit carmens and collected every signature possible.  Record setters, racers, techs, officials and staff
20 years of BMST

Does Burt Munro and his Indian have a nice tribute area to his memory at Bonneville ?

There is no monument to Munro in wendover that Ive seen.  I believe Invercargill NZ has one.
There is a good living history of people who remember Burt at bonneville however.  So thats kind of special

[BomberMann650]

Things I learned on the salt.

1) the elevation is not 4234 ft
2) more boost is good
3) just because a part hasn't come loose yet, doesn't mean it won't
4) remember to flip the visor down
5) gearing down won't necessarily bring speeds up
6) more boost
7) hot lapping without a kickstand is incredibly difficult

[Lostboy Steve]

Things I learned on the salt.

1) the elevation is not 4234 ft
2) more boost is good
3) just because a part hasn't come loose yet, doesn't mean it won't
4) remember to flip the visor down
5) gearing down won't necessarily bring speeds up
6) more boost
7) hot lapping without a kickstand is incredibly difficult

Awesome. I wish to get out there one day, if even just to watch.

[HondaMan]

Congrats on a successful run!
It's not easy on the Salt: it's a different environment. I used to help the guys at MSA do their builds for their runs every year (I think they still hold the 1000cc Lakester Class record, using a modified KZ up to 1500 cc in the car). The electronics go berserk when speeds exceed about 80 MPH over that salt. Radios quit working and computers start making up their own numbers unless things are shielded like for a nuclear blast! We never could get the Kawi EFI to work right there, went back to carbs in the early 2000 era.

[BomberMann650]

Things I learned on the salt.

1) the elevation is not 4234 ft
2) more boost is good
3) just because a part hasn't come loose yet, doesn't mean it won't
4) remember to flip the visor down
5) gearing down won't necessarily bring speeds up
6) more boost
7) hot lapping without a kickstand is incredibly difficult

Awesome. I wish to get out there one day, if even just to watch.

If you're gonna come all that way, might as well bring a bike.

A bonneville "race bike" doesn't have to be an elaborate build.  There was a production hiyabusa making pass after pass after pass.
All the while - the bigger teams were down in the pits trying to keep their rigs in one piece

[Stev-o]

Things I learned on the salt.

Congrats.  How'd the bike do?

[Tracksnblades1]

Things I learned on the salt.

1) the elevation is not 4234 ft
2) more boost is good
3) just because a part hasn't come loose yet, doesn't mean it won't
4) remember to flip the visor down
5) gearing down won't necessarily bring speeds up
6) more boost
7) hot lapping without a kickstand is incredibly difficult

Well done…

Looks like number 5) may be that dastardly horsepower/frontal area wall….🤔
And number 6) will move it a little higher…😁

[BomberMann650]

Things I learned on the salt.

Congrats.  How'd the bike do?

Off the trailer it ran 98.5 mph without issue.  Continued flogging netted diminishing returns.  Ran better stone cold.  Go figure. 

The fact the frame could kiss 110 without feeding back some bad vibes gives me hope for the next race.


 

[BomberMann650]

Congrats on a successful run!
It's not easy on the Salt: it's a different environment.

Thanks HondaMan

The great white dyno is a cruel mistress.

[BomberMann650]

Mulling over the next seasons attack plan already.
Obviously, there are MPS and G class records that could be worked towards. The plan always included a slippery looking bike.
But the real fun lies in the horsepower gains.  The quest to stuff more air and fuel into the motor than before.

There are a couple of paths to more performance i'm considering.
Easy experiment - An Ice box cold air intake.  Hopefully compensate for the DA and temperature, and the tiny turbo.  The exposed velocity stack looks cool.  But we all know how much cbs appreciate a box full of slow moving air.  I imagine a moonshiners flute might have an appreciable effect
Maybe add cooling fins to the manifold itself while im at it.

Also need to get my big valve head finished off.  The port matching i had done for the intake plenum could hold some value. Otherwise i have to work on the stock head that already raced.

592cc pistons are also a possibility.  But not something i can do at home currently.

Rumor is mikuni offers oversized float needle seats too.  While the rebuild kit was genuine - the valve may a possible bottleneck in the gravity system.  Float level was as high as I could get it (verified with the t-jets hose)

Im also wondering if a different throttle slide profile could correct my WFO issue.  Not that i have a problem setting a throttle stop.  Its just a shame i've encountered a limit in the relationship between turbo inlet and venturi sizes.

Then there cam and ignition timing to adjust.  The timing between dyno sesh and race day were unchanged.  The 650 factory cam was set to oem position.  Resulting in a the healthy midrange punch, but rolled off the high rpms too much. 
The ignition was also doubly retarded. With static set closer to tdc at idle it never got close to 30* full advance.  I don't think my boost retard sensor ever came into play, as i had hastily cranked up its adjustment.  In hopes that it wouldn't trigger a 4 degree pull.

There are a few trifle some details i need to address with the chassis.  The chain guard i originally made was overkill, and kinda noisy as it bounced around.  A simpler and stronger one is on the to do list.  If i aim to run at usfra test n tune.  I'll also have to put a metal strap around my battery.

Gotta address the frustration caused by my shift linkage.  The damn thing liked to fall off on my way to the return run starting line!  Jaylin caught me reconnecting it with zip ties and sent me back to the pits for a bolt.  The second time the bolt backed out of the bearing block and got bent to heck as it folded under the foot peg.  I was able to find the offending fastener and get it sorted before backing up a 106 mph run.

Either way, i hope to match my top speed when i run it off the trailer next season.

Licensing up to 130 would be sweet.
But i'll need a gps speedometer for that

[BomberMann650]

Picture for attention

Scooter Grubb should have his high speed shots available soon.

[BomberMann650]

Race season is officially over.
Currently caught in the doldrums until next season.
To occupy some time, the head and turbo system have been disassembled for inspection
... and stuff

A touch of port work and another attempt at swapping valve guides.  Won't be going crazy and some of the effort will be deferred to those more experienced.

Discovered the alleged compressor map for the vz21 turbo.  It is truly underwhelming by comparison.  Along with being prone to oil blow by.
Effiency losses all around and a tiny island nowhere near my target.  Not much can be done to change its nature.
Yet im not in a space to begin another radical fabrication project. 
It may set a few more records yet,  Before upgrading that component altogether.
There are a few small things the die grinder can fix.

The carburetor will be getting another mod.  Bigger float needle and seat borrowed from a bigger carb.  Will find out if the extra volume flow is enough to support more boost.
At suggestion of FBM turbo Dave, i changed the slide needle to something that doesn't open nearly as quick.  Hoping to solve the 3/4 throttle problem.
Should all else fail, i've been talked into a water/methanol injection setup.

Studying motorsports technology via the web is headache inducing.  Popular programs regurgitate the same basic information over and over.  Elsewhere an engineering college publishes an abstract with some elegant mathematics.  Which flies over the head of the average farmer and their fun little tractor.

An exciting announcement will come in the next couple of weeks.

Now to buy some wind.

[BomberMann650]

Examining the vz21 turbo, found there is little room for improvement.  Literally, its just that small.

Yet, two areas could accept minor modifications.  While the carb adapter is not ideal with its bent tube inlet. The compressor housing inlet also had a serious taper that finished pretty far from the impeller blades.  A bottleneck from the factory that may or may not be helpful.
The local machinist was able to relax and extend that taper for me.  His boring bar cut a nice taper.  Effectively porting the turbine inlet.  If Bernoulli is on my side, the boundary layer should have moved... elsewhere - hopefully easing the flow into the turbo.

He also helped me run the numbers on the volutes dimensional area.  Theres some percentage of area to be gained at the connection between the turbo and the intake manifold.  Which i will work over by hand.  There is not a lot of material removal required to add double digit percentages to such a small part.
Port polishing deeper into the snail isn't very practical due to spatial constraint.  The factory surface finish is actually pretty good.

Not exactly reinventing the wheel of turbo performance here.  It's a small step in a refinement process before going back to the cutting room for a total parts swap.

Looking back after Learning more and more about turbo systems - I wonder if the boost pressure issue i had on the track was near the limit of the turbo efficiency. 
While the bike kissed 110 in the mile, i observed a small drop at the boost pressure gauge.  Which correlates with the data on the compressor map.  The turbo spooled with such ease, i assumed it was a good thing.  Now it begs the question if the higher engine rpm is too much for the little turbo.

The initial plan was to reassemble the engine with the same static compression as before.  Then increase the boost pressure well into the teens as compensation for the adjusted altitudes.  While nudging the cam timing back and the ignition timing forward of the "as raced" setting.
Rethinking this - again - a higher static compression ratio and 1 bar of boost would net the same dynamic compression ratio at bonneville.  Advancing the cam and dropping the rev ceiling while gearing up the sprocket may create the low rpm/high torque scenario required to go faster.

Not that i ever got into top gear before the mile.  Will get to use two miles of track next season!

Decisions can be made later.  Would welcome input.
Gotta go set up the die grinder now.

[HondaMan]

Some random thoughts:
- If you do 592cc, use 0.0008" piston-bore clearance, no more - unless they are forged pistons. Then, stick to their minimum clearance recommendation.
- Don't make shiny-smooth intake tracts into the engine: a tiny border layer, built by slightly not-smooth port surfaces, makes lower friction thru the intake tract. S&S taught us about that in the late 1960s HD engines.
- Take a close look at the faces of the inlet valves, see if they came with the little 'tulip' edges, and grind them off in a lathe if they are there. Same for exhausts. This helps drop the air temperatures during passage, cooling the head(s) a bit at high RPM.

What was your top RPM?

[BomberMann650]

Thanks hondaman.

The dyno guy claims to have a recipe for valve jobs that work with smaller cams.  Will leave it up to him.
I haven't decided on a big piston build yet.  Already have concerns with cfm and ve and surge/stall at stock displacement.  Magee proved the CB can do more with less anyway!

Never got a tach that worked with the dyna 2000, looking at my gearing charts to estimate rpm for speed.
at 106mph the motor may have been turning 8700 rpms.  Wasn't enough horsepower to support the drop into 5th gear.  Would have benefitted from some extra grunt around 7krpm.

Not sure if the surface finish of the intake runners will make a lot of difference with the draw through setup.  Since the fuel is getting absolutely gobsmacked at every turn.  Seperation inside the compressor, then slammed into the wall of a plenum, eventually finding its way to the ports.  Where it met a ledge at the junction of manifold and head.
Maybe a rougher finish would help get it back into the air?  I don't know.

That water/meth injector at the compressor outlet would solve a couple problems.  Its allowed in the Gas class too.

[BomberMann650]

Some additional tinkering done today.

Porting the compressor volute took things from an 0.95" outlet to a 1.12" - and it tapers down to an inch at the tongue 1.8" away.  Crunching the numbers revealed a 25% volume expansion in that area.  Naturally had to make this match the inlet of the manifold - couldn't really hog out the walls of that little charge pipe (1.25 od x 1 id).  A slight taper smoothed things out on both ends

In the process of cleaning out the chips.  A pinhole leak was discovered in a weld.  So out came the tig rig to fix that.
With the tig welder already set up.  Attention was turned to the hot side of the turbo.  Initially couldn't remember where the stash of iron filler sticks were.  Of course they turned up this morning.  Having already ordered a fresh box. 
Oh well, no more putting this off.
Cut the internal waste gate shaft and removed the flapper.  Polished up the weld area and went to work plugging holes.  Now i won't have to contend with the crummy pressure regulator during reassembly.

That oe gate was the sole reason the exhaust secondary made a wild turn towards the top of the motor.  Had i done this mod during assembly - things may have taken a more conventional appearance.  I digress.

[BomberMann650]

Spent some time working over the iron side of the turbo.  And the flange of the secondary exhaust pipe.
May be gambling a little with the radius on the diffuser.  But it is a design feature found in some of the higher performing turbos.
Tapering the inlet and outlet to a larger cone was tough.  Not because of the tiny size, but because of the material itself.  By comparison - steel and aluminum are virtually clay.
Borrowed the idea to chamfer the outlet from the diesel performance people.
To do all this with any sort of accuracy, the gasket was modified.  Opening the hole closer to the i.d. of the secondary pipe.  Now the exhaust charge won't hit a sharp ledge before entering the turbo volute.

This may be the only ported vz21 turbo on the internet
How will these mods impact peformance?  Can't say until it hits the dyno again.

Set up the waste gate for 12 psi while things were apart for inspection.  Should be a good starting point for the next round of tuning

[BomberMann650]

Calculating compression ratios and came to a conclusion that 7.8:1 is not good for the horsepower target.
The budget for 10:1 race pistons isn't much fun to look at either.

But there's a tig welder in the corner.

A clay model illustrates how 1cc could be reduced from the chamber volume.
Lowering the cylinder deck to .025" with stock bore bumps compression up to 8.8:1 - still leaving ample room for the valves.

This may be a bad idea.

[richmagee7]

Keep tinkering Bombermann.  All very interesting though I haven't delved into learning the ins and outs of turbos yet.  I'm hoping to pick up a close ratio 5th gear and mess with gearing/sprockets and AFR when I get back to messing with my race bike.

Rich

[Old Scrambler]

Bomber..............
According to NASSA and USAF data, the surface walls of a round tube are all drag ...........
flat walls offer large areas for laminer flow with drag reduced to the corners .............therefore, a smaller square or rectangular tube will flow as much or more than a larger area round tube.

Getting the fuel to atomize properly is greatly inhanced by using an extended emulsifier tube similar or borrowed from a 2-stroke carb.

The larger a defined air-box can be is best at Bonneville.

[BomberMann650]

Magee - turbos are witchcraft - Jeremy Clarksons words, not mine.
Going this route has become as much of a scholarly effort as it is a race build.
The nuts and bolts part of it is straightforward enough.
Will be interested to see your close ratio mod and if that allows you to power through top gear faster.

Dennis, my brain hurts from all the port flow theory.  If I ever completely revamp the intake side of the turbo, i may give square ports a whirl.  For now, the round tubing remains round.
I do have a napkin sketch for a ram air box in mind.  More on that later.

The whole dynamic changes once you begin force feeding an engine.  The stock head with 8psi of boost theoretically made 54hp.  Enough to enter the mile at 105. 
From the study chair, it would seem volume is the name of the boosted game.  If there is the necessary space between the turbo and the valve.  It will all come gushing in under pressure.  The trick is getting it to chill out and stay in.

Volume was definitely achieved with the daily grind... may have sent her a little too hard.
In spite of making a transfer pattern to port match the intake.  Something went over the edge and didn't line up well at all.  Looking through the intake seat, could see the o-ring groove on the intake casting.  Had hoped for a little bit of an anti-reversion lip but not that much.
So the intake manifold got some reshaping.  Will ultimately have to reposition the o-ring groove with a little bit of jb weld.  Needless to say, the intake ports are big enough.

This is on top of all the frustrations had with a bad batch of carbide burrs.  The 1/4 long shank tools were not balanced.  Thankfully, it was nowhere near my face when the shaft bent and turned into a propeller.  After cutting the the shanks down, the balance was still trash.  Another tool bent inside of a port.  Leaving behind some interesting rifling before it could be stopped. A third tool simply snapped off the cutting tip.  Of course, that happened to the favorite one.
Proceeded to wear out a set of 1/8 shank carbides in the process of finishing the bowls and manifold.  Then ran through a fistful of sanding drums to smooth and texturize. .

In other news; accidentally started a fight in the sohc4bikes tech forum.  Only wanted to know what the stock stators amperage capacity was.  Got an anwer, but the discussion deteriorated from there
An electrex alternator kit is on the list now.  Thanks to the forum

[BomberMann650]

Postman brought more go fast goodies to the shop.

In spite of going through the chore of porting the vz21.   Also won an ebay auction for a rhf3 turbo.  Why?  Because the more efficient rhf3 compressor housing and impeller are cross compatible with the vz21 cartridge.  Making it a relatively painless uprate for now.
Though it would require the modification of the flange at the manifold inlet.  This hasn't been decided on yet
Easy method would be cut the charge pipe and use a silocone sleeve for a joint.  But that would make the exhaust pipe do all the heavy lifting.  The alternative is fabricating a flange for the compressor housing.  Making it forever bespoke to this bike.

Speaking of the intake manifold.  Now thats its ported within an inch of its life.  The smart decision to make the system sealed is a copper gasket.  Which will be fashioned out of 30 thou plate stock, annealed, and garnished with lemon.

The 4.5mm float needle and seat also arrived.  Its a pn# from a larger hsr48 carb.  Not a direct fit to the older tm/hs40.  Which means i need to call the friendly local machinist and ask if hes up to turning some of the brass shoulders down to match the original.  The collet chuck ought to be gentle enough on the part
This mod adds 16% more area the the float valve of the carb. Need to make certain the fuel elbow and internal passage are adequate as well.

Found the chunk of crud that was causing it to leak fuel at the starting line too 😆