Bockscar 2.0

[Rex Schimmer]

Bob,
Use silicon/bronze tig rod, low weld temp and much easier on sheet metal welding than normal steel filler rod. Not for anything structural but works well for brackets and sheet metal.  Go on "Welding tips and tricks" if you need to see it done or just try some on a piece of metal pretty easy to make pretty beads.
One trick is to keep the arc in the middle of the bronze puddle and push it along, don't get the arc ahead of the puddle as it will melt the base metal and then the bronze will mix with it and not be strong or look good.

Rex

[Stainless1]

Yep, TiG brazing would have been easier... I tried multiple filler rods, before I ended up with stainless 308L... it mixed best with tube and light plate.  It was kind of a bitch getting them joined... guess I should have paid better attention when I audited that welding class 40 years ago. 

I was gonna tell ya I got so pissed off I just cut the cage off and started again... but some of ya might have noticed that was the bottom of the car

But it is sealed up and that part is over... shot primer on, black tomorrow, or sometime...

[Stainless1]

The new parachutes for the car have the attach points wrapped in leather... and the flame cover attachment over the loop... just a bit fatter than the previous chutes.  I tried several quickie solutions... including building a bridle. I didn't like any of them...

So while I had the car around the welder I decided to cut the old car attach point off...

And make one with a bit more room.  This moves the pull point down about 3/8 inch and back a 1/2 or so... close enough... I don't think it will change the moment arm significantly since it attaches to the same point of the car
I will weld it to the frame tubes and chute tube like the last one as well as to what's left of the old one.  This one will allow the use of a larger roller if I want.

[sabat]

Nice work!  I need to find a welding class to audit

[Stainless1]

Dean, check your local community college... you are young so I'm sure your hands are steadier... the one thing you have to teach yourself is welding "out of position"... the older ya get the harder that is.
I'm just glad I didn't have to make a living on my welding skills   

[Milwaukee Midget]

It comes down to this question:
"Do I trust these welds at 250 mph?"
The Bockscar has put enough red hats on knowledgeable people that you can draw on consensus.
Bob, your welds are fine.

[Stainless1]

Well the only weld that's come apart was an exhaust mount welded to the pipe... a little too much vibration I guess.  (where's that knock on wood emoji) 
My welds seem to stay welded, but some are not always as nice looking as I would like. 
I guess that comes from not being a trained professional... 

250 MPH... originally I thought we could get there with the H class turbo motor... Maybe... Well I guess we will see.
So far 2.0 is exceeding our expectations 

[PorkPie]

So far 2.0 is exceeding our expectations 

...let me confirm that.....

[Stainless1]

Welded the new chute attach points in... will let it cool down and then I'll touch up the paint. 

[Stainless1]

Chute attach point is painted and complete... made a new 1.23" attachment tube... Ok made it from a  piece of 1.250 solid aluminum round I had and it took .020 to clean it up.  Probably will need to make a new release strap since I changed the length required. 

Motor has a bit of leak through the exhaust valves... so I'm pulling the head to take a look. 

[Milwaukee Midget]

Motor has a bit of leak through the exhaust valves... so I'm pulling the head to take a look.

All of them?

[Stainless1]

All 4 cylinders... 2 cylinders were leaking about 20% after WoS, I pulled the head, and lapped the leakers... the head was fresh for SpeedWeek, so there's probably 70 miles on it...
The leakers have actually moved around from cylinder to cylinder... They are very small stem valves and tend to weep a little if you shut them off too hot.... They will seal back up... but I need to look at them.  I'll pull the head off, take it apart to inspect, then probably take it to my head person to get touched up... Thinking of changing the exhaust to Inconel, but we will see what it looks like in there.
The leaks didn't seem to bother performance, he we 246.5 in the last mile of the qualifier and 246.7 in the middle mile of the return before the sprocket went meth head...

[Stainless1]

Well everything looks fairly normal inside... I did find some very fine salt particles laying on top of the #1 and #2 pistons.  My bad... I didn't clean the filter before we headed home and I failed to put the plug in the scoop.  It must be time for a new filter...
The pistons all look about the same, not seeing any signs of detonation
The head... does anybody else see blue stain around the intake valves... Not sure why the new valves in the #1 (far right) look so much different... I know they are a different brand, couldn't get the same when I had to replace those 4 last year due to the injector issue in that cylinder. 
I'll get the head broken down and over to Deni for a professional evaluation... maybe next week. 

[floydjer]

🤔 little restriction exhaust side?

[Stainless1]

I know the turbo created a lot of back pressure.... it was a small turbine w/.63 AR... made lots of boost quickly, making you work to not spin the tires in 1st and 2nd.  Hopefully I will solve that with with a larger turbine and a .83 A/R turbine turbo which should bring the boost on slower. 
 
I think the blue around the intakes may be stain from the VP C16... anybody else see that in their motors?  I'm running about .8 Lambda (11.7:1) so it isn't "pig" rich as shown by the piston tops, but they were not blue... just the area around the intakes...

Happy Thanksgiving from the Bockscar team