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

[changzuki]

Originally Posted by sheepdog 44

The new stenciling looks great! I'm interested in what exactly is underpinning the car and just how you got it so light. What's the weight reduction compared to a stock car? I was very envious about how small your car is. I parked next to a Honda del sol today, and even that has got me beat on frontal area by about 5 inches on every side.

I didn't realize you were that sick! I admit i was really thrown off by navigating the tulip diagrams as well. I'm used to having the route handed to me well before hand so i can analyze the road grade and lights and stops signs so i know in advance when to coast. MPG routes should resemble a commute you plan to take 5 days a week. Not obscure directions to a hidden treasure!

Thanks for your kind words Sheepdog44! Part of the sick-deal was likely the result of the 2 weeks of final push leading into the Green Grand Prix, and it arrived with a vengeance!
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You're correct! Centurion is quite small but I have to throw something in here:
You were a perfect fit dimensionally, and at 6ft I cope and do ok. Out of the car, I felt like a gargantuan next to you. Well, recently, I had the pleasure of meeting Redneck in person and guess what? He is a gargantuan next to me: Actually he's just a really big guy you wouldn't wanna mess with - but history was made yet again and we got him into the Centurion (vaseline and a shoehorn! )... With no room wasted we did go for a spin as well. Not sure what will come out of that visit but maybe we can just say it's a heads-up, something to watch out for down the road ....At least that's what I'll be doing!
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Back to the tulip map... If Stage II would've been another fuel economy based event, I'd have used plastic bags or whatever was necessary to get through it. Another consideration I wrestled with was the condition of some of the local roads... The visualization was that part or all of the car would be swallowed up by a sinkhole and it would have to be sent home in several boxes via Fed-Ex.... This car regularly sees road battle but not under a stopwatch following a tulip map - clearly that was out of my league....
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I do thank you for sharing that portion. As close as I can tell, Centurion with us two blobs was within 25 pounds of a total weight of 1340 lbs. This is part of the details I'm getting ready to publish here on the forum starting this weekend. So you know your weight, and I know your weight and judging by a partially eaten pizza upon your arrival, and the ground clearance on your side of the Centurion, I believe you were accurate. So, subtracting both our weights from the total leaves approx 1030 lbs of car. That is within the 25 lb margin of error in my totals and leaves us with an approx 1000lb (+ / -) Centurion in race trim. This is nearly a 200 lb reduction from the original and for the event is ok, but I am reverting back to street trim. This will make more sense when the entire context is laid out.
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More details forthcoming!
~CrazyJerry

[Dauntless]

Ah, Jerry, THERE you are. Didn't figure you'd be answering questions at ES.

Since all the Triumph equipment has become hard to come by, I'm curious what you think of the possibility of substiting the Miata as a source. A few pictures below.

The wheelbase is 7 inches longer, I don't have a track for it but I'm sure it's a bit wider. I suppose there's substructure to be built on, I've seen artwork of the Spitfire frame, such as what I included.

If you don't like the Triumph drivetrain I'm sure this will bring some improvement.

If anyone familiar with the Miata frame as ideas, that'll certainly be of interest. But Jerry built the actual car, I'm most interested in his thoughts.

Good luck with the TriMagnum.

[TedV]

Miatas are used as donor for Locost Super 7 home built/kit cars all the time. Not sure how the trans ratios will match up to a 3200 RPM diesel. Jack McCornack got 128mpg with his Locost based roadster. Could be better with better aero.

[changzuki]

Originally Posted by Dauntless

Ah, Jerry, THERE you are. Didn't figure you'd be answering questions at ES.

Since all the Triumph equipment has become hard to come by, I'm curious what you think of the possibility of substiting the Miata as a source. A few pictures below.

The wheelbase is 7 inches longer, I don't have a track for it but I'm sure it's a bit wider. I suppose there's substructure to be built on, I've seen artwork of the Spitfire frame, such as what I included.

If you don't like the Triumph drivetrain I'm sure this will bring some improvement.

If anyone familiar with the Miata frame as ideas, that'll certainly be of interest. But Jerry built the actual car, I'm most interested in his thoughts.

Good luck with the TriMagnum.

Hi Dauntless,
Welcome to ecomodder! I do visit ES off-and-on but it's usually under the cover over darkness. The Trimagnum is still waiting - I've been blown so far off course this year - blah - blah - blah...
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Substituting another car such as a Miata is certainly intriguing. I do not know the Miata intimately so my thoughts are based soley on what I can see in the pics or read on the net.
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- On the surface there would be advantages such as parts availability, wheel choices, and a bit more room.
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Some thoughts that need looking into are:
- I read where they've put the engine behind the front axle for better weight distribution. Look at your oil pan and see if the oil sump is on the rear of the engine, and does it have to be that way (for clearance reasons?) The Kubota D850 oil pan is not like this, it's deep at the front of the engine and this may (or may not) be an issue.
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- The Miata I believe has both a front and rear subframe and they appear to be connected by a tunnel of sorts.... So to actually create a custom body (Centurion for example) may or may not be receptive to this especially over the long haul. Why? If using just the Miata platform, where would the strength the Spitfire center-frame provides (as a back bone if you will) come from? I may be incorrect but I'll guess that the Miata steel body structure adds to the overll rigidity/strength. This may not be an issue but I can't take my eyes of that Miata tunnel piece.
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- Hopefully the Miata you have is one with manual steering. Even if it is not, it would be easy enough to decommssion but you're up against some tough competition with the Spitfire here. In fact, the simplicity, durability and lightweight of the Spitfire front end is a hard combination to say no to. It's been time tested on and off the track. It may seem a bit nit-picky, but I believe weight is a big factor with this project regardless of what platform one uses - remember - the D750/D850/D950 are all in the 17-20 hp range (depending on the chart you look at) so if you're looking for optimum results, an overall weight target was set with the original Centurion and that 1200 lbs is a challenging target to break. This becomes a greater challenge if you're already starting out with a heavier/wider donor. Quick glance on width is approx 51 inches (Centurion) and 63-65 inches (Miata)...
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- A little creativity may be in order but, does your local area/state require an emissions inspection? Where I am, year xxxx and up have to pass this and it's all done via the computer by way of the OBDII. If a car falls into this category this could be a problem...
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- Assuming for a moment one would use the entire Miata and just do an engine transplant: Would you be willing to do some streamlining? A Miata is generally a low-slung vehicle but it (like some of other smaller cars) is a bit wider than Centurion. It all adds up if you're going for the gold so-to-speak...
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- Also, TedV beat me to it, and Jack McCornack has "Kinetic Max" and it uses a Kubota 1100 cc turbo. This is totally worth looking at as some of his outstanding work may be also applicable to your project:
See Kinetic Vehicles
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- Not sure exactly what you have in mind but all of the above aside - I like it!!!!!!

~CrazyJerry

[changzuki]

Prelude to details of Centurion's success at the Green Grand Prix...
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1st, Centurion owes its success to R.Q. Riley who designed it and gave it life. Had this never happened, this thread wouldn't be taking up your time. The plans for the original build are solid, and anyone looking to replicate what CrazyJerry's Centurion has done needs to start with them. Deviations can be made but using those original blueprints will yield a car that falls easily within the mpg figures that are supplied - at least that is my experience and the experience of the original that was built and tested back in the early 80's. The original magazine (Mechanix Illustrated) is defunct now but the plans are still available from the original creator at:
128-mpg Diesel-Powered Sports Car
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2nd, The initial reason for registering/participating in the Green Grand Prix was not about winning. It was also not about collecting the grand prize of $1000. In fact, if you could see where I live, it would be really easy to have used the $1000 prize to, well, do alot of things. As as side note, 100% of the winnings were given back to the Green Grand Prix as a donation:
SUNY Canton staffer hits 200 mpg in his ‘Total Recall’ car at Watkins Glen Green Grand Prix
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So ,why go at all? As Centurion got broke in and I made changes, the new mpg numbers were posted on the front fenders. You cannot imagine how much criticism this generated - both on and off the net. To the point where I almost scrapped posting them entirely. So, when Bob Gillespie invited us ecomodders to the Green Grand Prix, I thought - perfect! Let the Green Grand Prix tally the results and whatever they are is what I'll post - even it was 25 mpg. (And since the Green Grand Prix results are posted on the net, I wouldn't have much choice anyway but to follow suit.)
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Admittedly, a few of my deviations from the original plans returned some impressive gains, and this also got me thinking that my numbers may just be good enough to "possibly" win the Green Grand Prix. Specifically, a previous West Philadelphia High School’s Factory Five GTM fitted with a TDI had turned in numbers around 160 mpg:
West Philly High School Builds 160 MPG Supercar, Win Green Grand Prix
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Centurion is lower, narrower and lighter than that car sooooo, might it do better? Judging from the lack of press, you might think not.
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With a target in the sights, it was game on!
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Looking at the factory five photos, the keen observer may have noticed a couple of things: It doesn't exactly fit the ecomodder aero template, and they didn't run wheel disc covers....
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Both of the above items also apply to Centurion...
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Also of interest: I studied the Watkins Glen raceway and elevation maps. If there was ever a competition designed exclusively for Centurion then this was it!! With its lightweight, I pretty much knew it could take the hills with no problem, and its center of gravity truly makes it corner like a slot car so it was pretty sure that any turns would be no problem (and they weren't)..
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This completes the yawning festival portion and now it is time to move on to more substance....
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~CrazyJerry

[UltArc]

I enjoyed that article.

And the elevation map helped a lot- though we'll do better next year knowing the corner speed limits are optional and just to follow the course speed limit. I had no idea the Centurion was in Total Recall- I may just have to watch it now.

[changzuki]

Originally Posted by UltArc

I enjoyed that article.

And the elevation map helped a lot- though we'll do better next year knowing the corner speed limits are optional and just to follow the course speed limit. I had no idea the Centurion was in Total Recall- I may just have to watch it now.

Thanks UltArc! The original Centurion was in the original Arnold Schwarzenegger 1990 Total Recall movie. Any recognizable image of the car in that movie are captured in the screengrabs in this pdf:
Total Recall Centurion Shots
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And yes, I was/am obsessed.....
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~CrazyJerry

[changzuki]

Exhibit 1: Running in Ski-Doo boot vs Sneakers.
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Many moons ago I used to dabble in the sport of Triathlon. During those years with the help of my best friend and fiercest competitor, I realized the value of lightweight, or stated differently, getting rid of excess weight. This really starts to take its toll when you're continually denied winning and one of the most glaring items seems to be those super-lightweight wheels on their bike.
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This Centurion has had its share of 13" wheels, and due to the odd 95.25mm pcd (bolt circle), they are hard to come by. The original steelies are not really that light in spite of all the little holes in them:
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Adding disc covers only made the weight problem worse, not to mention throwing off the balance:


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Then there was some American Racing Wheels (NOS 1982). These were a 100mm pcd so I had to get adapters... Another bad move. The wheels were heavier than the steelies and the adapters didn't center well so the ride was like driving over an endless set of railroad tracks:


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Then there was a nice set of American Racing Libre wheels. They looked nice, balanced well, but these too were heavy...


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Continuing the search, it was a miracle that I stumbled on the ad for the wheels that were on the original Centurion! All I had to do was give up my life's savings - done! The wheels needed refinishing which took only 2 weeks or hard labor, and when I mounted them on the car I may have had an orgasm! That blissful moment faded however when I actually drove the car. It felt like honey. Thick gooey honey..
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The most beautiful wheels I ever saw were pigs - oink - oink!
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With just a few days before the Green Grand Prix, the sky opened up and a brillant beam shone. When the beam finally ascended back up into the clouds, a wonderful set of wheels remained! They were new, drilled for the 95.25mm pcd, had a retro look, came prebalanced, and-yes! were advertised at a mere 9 pounds!!! "BUY IT NOW"! Thank you VTO wheels!
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These wheels are also very easy to fit coroplast wheel discs to. (I had these at the Green Grand Prix just in case...)

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So, ending Exhibit 1 - the wheels:
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VTO Retro - 9 lbs
With 155x80r/13" tires - 12.5 lbs
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Wheel/tire combo - 21.5 lbs
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~CrazyJerry
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...Wow, it's after midnight... Over and out!

[changzuki]

**** Adding a couple of notes that go along with the above posting concerning wheels.
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New 15" wheels are readily available for Spitfires by a few manufacturers. And if a low profile tire is used, Centurion's rear wheel wells will house them. The front's will too but be sure to get the correct offset or they'll scrub on the turns. Normal driving shouldn't pose any issues. However, if you are planning to follow some of the General Lee's stunts then it's going to be really close when you bottom out the front suspension.
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15" wheels can also give a higher top speed or same speed while lowering the rpms a bit albeit at the expense of some extra weight.
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If considering this upgrade, also consider upgrading the factory wheel studs. Spitfire use some of the smallest I've dealt with and of all things, the wheels are "lug centric" not "hub centric" - meaning the lugs center the wheel in addition to dealing with other torsional stresses.. The originals for this 1966 base are (3/8"-24) 17mm Hex. It's all these little things that add up and help to give Centurion it's very light weight. Substitute wheel studs have been successfully used and there's an excellent write-up online at:
Upgrading Triumph Spitfire Wheel Studs
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~ CrazyJerry

[sendler]

Originally Posted by changzuki

[B]
With its lightweight

I add mass to my motorcycle when in competition.