Urba Centurion Update - (Kubota diesel, 100+ MPG in mixed driving - Fall 2012 on)

[HHOTDI]

...is that a fuel efficient Mirage that is photo-bombing your pic of the Centurion??!!
:{)

[changzuki]

Originally Posted by HHOTDI

...is that a fuel efficient Mirage that is photo-bombing your pic of the Centurion??!!
:{)

Lol - yup! The little green "gas-hog" just had to get in the photo!!
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Hope you're having a good summer!! :{)
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~CrazyJerry~

[MetroMPG]

Jerry - the wheels look fantastic. Nice job.



Clarification: are the tires new too? What did you go with?

[changzuki]

Originally Posted by MetroMPG

Jerry - the wheels look fantastic. Nice job.

Clarification: are the tires new too? What did you go with?

MetroMPG has a sharp eye!!
The tires are in fact new, and of a different brand. The Douglas 155/80R 13's seemed to wear out quickly all things considered. So, I decided to go with Cooper Trendsetters P155/80R 13. There is a width difference between these two brands...
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Below is the size stamp on the tires.
Here's the Douglas brand:
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And here's the Cooper brand:
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Here is each tire side-by-side (Douglas left side / Cooper right side):
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And here's a rear shot comparison (Douglas left side / Cooper right side):
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The Coopers do not contact the rear skirts under any condition but the Douglas tires did.
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~CrazyJerry~

[Xist]

How big is the tread patch on the Coopers?

[The Toecutter]

I don't know how I missed this topic, but damn this build is impressive.

I was skeptical of the Centurion's claimed MPG figures in the plans sold, but you've proven the concept. I suspect the CdA of the Centurion is similar to a Spitfire with the top up and the latter probably could get similar efficiency if set up with the same engine/tires. It is not unusual for the stock Spitfire to get around 40 mpg with its 4-cylinder gasoline engine.

I've been building an electric Triumph GT6. With aero body panels, the goal is 100 wh/mi @ 60 mph. The math says its possible, but I haven't had a chance to test that yet. I've always wondered what a GT6 or Spitfire modified to look like an ADU1B LeMans Spitfire with the appropriate aero to match(according to Jigsaw Racing, 111 brake horsepower to do 137 mph) would do with an inline 6-cylinder 3L turbodiesel engine from a Mercedes 300 SDL, with the injector pump tuned with wider threads to allow 300 horsepower. I think an 80+ MPG car that can rip off 11 second 1/4 mile drag races and top out at 200 mph is possible. It would require a lot of expen$ive modifications to make that possible and reliable.

This Centurion build of yours certainly exemplifies the efficiency of that little Kubota when placed in a chassis that is sufficiently low mass. I've read of a Honda CRX that used one that got around 90 MPG. I've so far read only the first 3 pages of this thread, but I intend to read all of it. Your results are phenomenal.

[changzuki]

Originally Posted by The Toecutter

I don't know how I missed this topic, but damn this build is impressive.

I was skeptical of the Centurion's claimed MPG figures in the plans sold, but you've proven the concept. I suspect the CdA of the Centurion is similar to a Spitfire with the top up and the latter probably could get similar efficiency if set up with the same engine/tires. It is not unusual for the stock Spitfire to get around 40 mpg with its 4-cylinder gasoline engine.

I've been building an electric Triumph GT6. With aero body panels, the goal is 100 wh/mi @ 60 mph. The math says its possible, but I haven't had a chance to test that yet. I've always wondered what a GT6 or Spitfire modified to look like an ADU1B LeMans Spitfire with the appropriate aero to match(according to Jigsaw Racing, 111 brake horsepower to do 137 mph) would do with an inline 6-cylinder 3L turbodiesel engine from a Mercedes 300 SDL, with the injector pump tuned with wider threads to allow 300 horsepower. I think an 80+ MPG car that can rip off 11 second 1/4 mile drag races and top out at 200 mph is possible. It would require a lot of expen$ive modifications to make that possible and reliable.

This Centurion build of yours certainly exemplifies the efficiency of that little Kubota when placed in a chassis that is sufficiently low mass. I've read of a Honda CRX that used one that got around 90 MPG. I've so far read only the first 3 pages of this thread, but I intend to read all of it. Your results are phenomenal.

Toecutter,
I too was skeptical of Centurion data and that was one of the driving forces to build one. I am no longer feeling skeptical! Your GT6 project is definitely of interest! Being small and light it has potential - but there are space limitations as well. Your GT6 falls into the same category as the electric Centurion here that awaits battery technology to take one more leap. Is there a build thread on your GT6? If so I'd like to follow your adventures with it!!
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~CrazyJerry~

[elhigh]

Jerry! You're not dead! I am very pleased. It's been a while.

I gotta say I miss the Centurion's relentless tearing up of all challengers in the economy contests. It speaks volumes for the simple, effective formula of less mass + less frontal area + low(ish) drag = crazy good mileage. When all this is over I look forward to seeing Kubota Racing dominating the top of the leaderboard while everyone else is battling for a distant second.

[changzuki]

Originally Posted by elhigh

Jerry! You're not dead! I am very pleased. It's been a while.

I gotta say I miss the Centurion's relentless tearing up of all challengers in the economy contests. It speaks volumes for the simple, effective formula of less mass + less frontal area + low(ish) drag = crazy good mileage. When all this is over I look forward to seeing Kubota Racing dominating the top of the leaderboard while everyone else is battling for a distant second.

Hello elhigh!
I never really went anywhere - I lurk. This has given me time to get a few other projects of interest done. During my exile, I've managed to start a local newsletter called "High-Octane" and all the editions are here for your reading pleasure! A few highlights from the series are:
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This GL1100 Goldwing that I customized and won Naked Goldwings Bike of the Year for 2020 (41mpg):
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Click to open this edition
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Supercharged this 1978 GL1000 Goldwing (51mpg):
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Click to read about the Supercharged Goldwing
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Am finishing up on this vintage 1950 Plymouth Patrol Cruiser (18-22mpg):
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This one's a dandy!
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Ran a feature on the Green Grand Prix in Feb 2021:
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Part 1 of the Green Grand Prix Newsletter
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And for March, completed part 2 of that with an edition about Centurion:
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The Amazing Centurion - MPG Marvel!
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Still waiting for lithium batteries to take another leap so the electric "CenturIon" can be put into service. In the meantime, I'll find lots more to do!!! Between the electric that is in waiting, and Mr. Riley's original prototype, the Centurion story isn't over yet!!
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~CrazyJerry~

[The Toecutter]

Originally Posted by changzuki

Toecutter,
I too was skeptical of Centurion data and that was one of the driving forces to build one. I am no longer feeling skeptical! Your GT6 project is definitely of interest! Being small and light it has potential - but there are space limitations as well. Your GT6 falls into the same category as the electric Centurion here that awaits battery technology to take one more leap. Is there a build thread on your GT6? If so I'd like to follow your adventures with it!!
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~CrazyJerry~

https://ecomodder.com/forum/showthre...ods-13532.html

I think the battery technology has been good enough for quite a while. The motor/controller technology took another major leap forward within the past 5 years as well. There is potential for the Centurion to consume < 150 Wh/mile as is if you keep the total weight under GVWR of the platform and use a modern synchronous reluctance AC drive system.

If you were to use a completely custom airfoil body designed to cut drag to the minimum instead of the Centurion body(Lets say, 0.15 Cd and 13 sq ft area), and the potential for only half that consumption(~70-80 wh/mi @ 70 mph) on a Spitfire or GT6 platform exists, an efficiency which the 3-wheeled Aptera is currently demonstrating while having a large-ish frontal area comparable to that of a modern small hatchback.

It would be interesting to get some roll down test data to determine the Crr and CdA figures for the Centurion though. I'd be surprised if it was an improvement over the Spitfire, which is already a fairly slippery car at a Cd of 0.39-0.42 with a tiny frontal area of 15.2 sq ft.