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In Japanese they call pie cuts “wagiri yousetsu,” which when translated into English roughly means “circle cut weld.” Though John Kuchta claims it really means, “no profit.” After seeing how labor intensive the whole process is, I’m inclined to agree with him.

 

The rest of the pipe was created using a combination of straight lengths of oval pipes and the wagiri yousetsu method, this tie along the oval’s major axis. Burn’s Stainless actually manufactures the oval pipes with a bend along the major axis. However, it turns out that Burn’s stainless isn’t open at 4 AM on a Saturday night. Funny, since the middle of the night seems to be when most racecars get built.

 

Using 3” oval piping versus a traditional 3” round pipe, frees up just shy of 1” of additional ground clearance for us.

With the main exhaust pipe tacked up, John’s attention turned towards fabbing up a new set of waste gate dump tubes. At the same time, he took the opportunity to play with a new toy, the Icengineworks block modeling system.

 

The Icengineworks header modeling kit eliminates time consuming trial and error that results from fabricating headers and manifolds on the fly. By linking together a series of small pieces which are the same diameter as the piping, the fabricator can plan out complex bends and create a physical prototype before cutting any steel.

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Protodad
Protodadlink
Monday, August 11, 2014 4:57 AM
In Japanese they call pie cuts “wagiri yousetsu,” which when translated into English roughly means “circle cut weld.” Though John Kuchta claims it really means, “no profit.”

I laughed. I think the first time I saw serious pie cuts was on a car from Japan (Feest CA18 powered S13 I think). It is a pretty crazy process but kinda tops the charts for incredible welding expertise.
emeyer
emeyerlink
Monday, August 11, 2014 6:07 AM
I would have loved to see a shot of that intake tube welded together. I don't know what's more impressive, the welding or how precisely those pie slices have been cut to leave no gaps all the way around.
gman
gmanlink
Monday, August 11, 2014 6:15 AM
Many beginner to mid-level fabricators dream about being able to do the 'pie cut' method. But once you do it a few times, you realize that it is a complete waste of time and materials. Not to mention you have introduced about 10x more points of failure in the exhaust pipe.

I'd avoid this method unless you absolutely can't find a pre-bent piece, or are building a show car.

Yes it looks cool, and yes you do have to have a certain skill to pull it off. Big props for doing it with oval piping though.
Rockwood
Rockwoodlink
Monday, August 11, 2014 8:38 AM
@gman: Read the article. The pie cuts were used in places where they could not use regular mandrels, such as for the oval exhaust. Oval tubing definitely makes this problem show up more often, as you can't just cut and rotate a U-bend to make compound bends.

BTW, proper backpurge, HAZ, material selection and support makes exhaust weld failures unlikely.
Monkius
Monkiuslink
Monday, August 11, 2014 8:46 AM
Wastegate... Position sensors. That's a new one. I guess precise boost control is much more important when you're pushing the limits, though.
mike156
mike156link
Monday, August 11, 2014 10:48 AM
Pie slices are pretty useful if you want to create a tapered bend, an odd shaped piece or need a bend that opens/tightens on the radius to get around things. Sticking to 7-10 degree cuts and then having adaquate short side length the pie slices bends will flow just as well as a mandrel bend of the same bend radius.

They are miserable to do and a complete waste if not abosloutely needed though. Particularly in stainless as you burn through a ton of argon if you are back purging as you go.
Rockwood
Rockwoodlink
Monday, August 11, 2014 12:01 PM
@ mike156: good gravy, didn't even think of the "FACK me" aspect of dealing with backpurging with pie cuts. That's either a huge amount of gas you're pissing our of welds, or a shit ton of time wasted on setting up your rig.
Jkuchta
Jkuchtalink
Monday, August 11, 2014 12:59 PM
Hey guys,

Thanks for all of the compliments! Given the time and material constraints, this was basically the only way to do this particular routing. Believe it or not, it was a lot of fun....and yes, it did burn up A LOT of argon.
Between the back purge and the champagne cup on the torch, the argon regulator was screaming, and was so cold it was sweating lol. I did use pieces of masking tape on unwelded sections, though, to reduce the amount of argon needed for the back purge.
BlackholeZ
BlackholeZlink
Monday, August 11, 2014 1:04 PM
I got to see it being tuned this week at Jim Wolf Technology. The Annual Z Convention was in San Diego and we took a trip over to JWT for a tour. This 240 is NUTS!
https://plus.google.com/104062409802045783531/posts/CQxPD6E5g6D
Chuck Johnson
Chuck Johnsonlink
Monday, August 11, 2014 3:13 PM
Glad you guys got to check out the car in person Dan. In the video, it sounds pretty frickin' mean. Just to clarify, (from your comment on Google plus) we decreased displacement because we were forced into the production class after being protested. Unfortunately, production class is the only place where AWD drive cars are allowed to play since they have such a distinct advantage on the dirt and salt. The records for the 1.6 to 1.99 (G) and 2.0 and 2.9 (F) production classes were well over 229 mph both set by AWD cars. The 1.0 L to 1.59 L (H) class just made sense since we could not go for the original Blown gas coupe (G) record we were shooting for.

Thanks for the compliments on the car though, I'm sure after this rather crazy weekend the team really appreciates it.
duke
dukelink
Tuesday, August 12, 2014 5:44 AM
Very nice fabrication. A tip, Spintech mufflers sell oval bends in the axis you were looking for. I run a 3.5" oval downpipe and exhaust with a 90 deg bend like the one that you fabricated on my race car.
Chuck Johnson
Chuck Johnsonlink
Tuesday, August 12, 2014 8:05 AM
@duke- nice tip. Checked them out they definitely an interesting and useful collection of oval bends and twists. Thanks
Fabrik8
Fabrik8link
Tuesday, August 12, 2014 5:09 PM
I've always wanted to play with the ICEngineworks mockup stuff. That's such a slick little tool.
I've never seen anyone pie cut oval tubing before, that looks like a complete bitch to do. I see a lot of oval tube exhausts but it's all mandrel bent with minimal welding except for transitions and braces/tabs.
Der Bruce
Der Brucelink
Tuesday, August 12, 2014 10:25 PM
Chuck I read your article and admired the craftsmanship late Sunday night, not too long after I read this:

http://www.autoblog.com/2014/08/10/bonneville-speed-week-2014-canceled-flooding/

Any rumors on the possibility of a September or October makeup?
Chuck Johnson
Chuck Johnsonlink
Wednesday, August 13, 2014 11:56 AM
Yep, this is the third time I've had an event at Bonneville rain out on me. I think the land speed racers biggest competitor at times is mother nature. From track surface conditions to wind and rain she's one tough cookie.

We are currently planning on the USFRA World of Speed event which starts September 5th. It's where Annie and I did the 130 MPH and 150 MPH club so it would be kind of cool to finally enter the 200 MPH club at the same event. On the downside, the last time I saw lake Bonneville in front of me, it was months before it dried out. In other words, I question if we will see Bonneville at all this year. Gotta stay optimistic though.

Right now 5523 Motorsports and Jim Wolf Technology are taking advantage of the extra time to get the car really dialed in. In the meantime, I'll just sit here with my toes, ears, and fingers crossed. If all else fails, we'll go back to El Mirage and smash our old record.
mike156
mike156link
Monday, August 18, 2014 8:31 AM
It's crazy it's not dry out there as Utah has been incredibly dry all year. One of the worst winters for snowfall in like 40 years, the great salt lake is WAY down, very dry spring...then it rained a couple times. Apparently that's all it took?
Chuck Johnson
Chuck Johnsonlink
Friday, August 22, 2014 11:42 AM
@mike156- Unfortunately, when you're racetrack is a dry lake bed it doesnt take much rain to ruin your day. Bonneville is basically where all the water drains off the moutains and then sits. I heard it was a record rain season in Utah. Did I hear wrong?
Micah McMahan
Micah McMahanlink
Wednesday, August 27, 2014 9:49 AM
When I see pie-cuts, my engineer brain kicks in and I only hear 'think all of the failure points and non-optimal internal flow!!!'....but then I just shut up and appreciate the art work.
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