Another LSR Fantasy Car: Caddy Cat?

[Harpo]

My last "fantasy" build (QuickSilver) was so much fun that I've decided to build another "LSR car that could have been".  I'm after the record for diesel powered cars, and the year is 1973, the first year of the Cat 3406.  With 300mph as the goal I'll need two of them (Ebay), and a car body that will go around them (spare Ecto1A). 

Here's the specs:    

Displacement:  1786ci  (29.2L)  
HP: 1100 @ 2100 rpm
Torque:  3700 ft lb @ 1200 rpm
Weight:  ~20,000lb
Cd:  .40
Frontal: 8 sq ft

This gives me a theoretical top speed of 285mph, so I'll be refining things as I go along.  It's going to take some serious overdrive ratios, but with the available torque this car should be capable of stopping the rotation of the earth.

I haven't decided what to call it yet, but the possibilities are fun: Caddy Cat? Catillac? Caderpillar?

Here's where I'm at so far, engines are built and grafted together, shown next to their new home.  

 

 

  

Edited October 26, 2018 by Harpo

[Ace-Garageguy]

Super cool. I love wild what-ifs when they're thought out with at least a passing nod to the numbers. This is great.  

May I suggest chopping the top? The reduction in drag up around 300MPH would be significant.  

[cobraman]

Cool ! Those engines looks huge.

[gearhedjon]

What about a wedge cut top? low in the front stock in the back. Those motors are HUGE

[chris chabre]

that kind of torque would be an issue out there. With that said...GET CUTTING... I CANT WAIT TO SEE THIS!!!!!

[Spex84]

This is demented, I love it

[Ace-Garageguy]

50 minutes ago, gearhedjon said:

What about a wedge cut top? low in the front stock in the back. Those motors are HUGE

If he's kinda thinking the mods through to break 300, he's going to be aware that a "wedge cut top" would create downforce, add drag, and slow the car down.

Drag is extremely important to LSR vehicles. In simplified terms, going twice as fast makes 4 times the drag. So going 300, there's 4 times the drag to overcome as there would be at 150.

But according to the laws of physics, going twice as fast, creating 4 times the drag, requires 8 times the power.

Anything that can be done to reduce aero drag is of paramount importance.

 

[jaxenro]

Why not remove the top entirely and cover the opening? Then use a bubble canopy or similar?

[Spex84]

From here, it looks like the engines are so tall they'll fill the body from top to bottom, making a chop impossible without the engines protruding. But that could be the angle...

Very curious to see where this goes

 

[chris chabre]

you have a rule book? If you need someone to look up stuff, I have an older book here. which reminds me, I need a new one actually since Im kind of planning a new 1:1 build

[Harpo]

3 hours ago, chris chabre said:

you have a rule book? If you need someone to look up stuff, I have an older book here. which reminds me, I need a new one actually since Im kind of planning a new 1:1 build

It would help!  I've tried looking online, but it's rather complex.  My fantasy build takes place in 1973, can you direct me to the rules and records that existed then?

[Harpo]

My estimate of frontal area was way off, after some measuring I think the least I can achieve is around 21 sq ft.  Even if Cd could be reduced to .3, this would still only give a theoretical top speed of ~250mph...  This might be enough for a diesel record in 1973, time for more research!

[chris chabre]

13 hours ago, Harpo said:

It would help!  I've tried looking online, but it's rather complex.  My fantasy build takes place in 1973, can you direct me to the rules and records that existed then?

I may be able to help with records but itll take me a few days to do some digging as Im not sure what the cutoff year of one of my books is. I think its 1968 unfortunately . The rules may be a bit harder as my oldest rulebook is 07. let me see what I can find out on a few land speed groups Im in on facebook

 

[Harpo]

Needing some other parts, I got the Revell Kenworth W900 kit.  This gives me the frame, wheels, tanks, and other necessary bits for this build.  I'll keep the chassis/running gear as narrow as possible, and take a slice out of the body lengthwise to match.  Radiators will be mounted at an angle beside engines (with appropriate ducts), driver will be up front between tanks. 

Here's the chassis under construction, it will be shortened at the back and extended in front.  Should make for a wild ride, sitting between two fuel tanks with 8 tons worth of diesel engines behind you!

[Codi]

Garry, Love the subject you've come up with here and the attendant engineering commentary that has followed.  There is going to be a LOT to learn (I have already btw) from this thread.  Good luck sir!  tim

[Oldcarfan27]

You gotta call it "The Caddypillar" and Cat yellow paint is a must! ?

[Harpo]

3 hours ago, Oldcarfan27 said:

You gotta call it "The Caddypillar" and Cat yellow paint is a must! ?

I like that!  Thanks to all for the kind comments! 

Here's the rear end, shortened and narrowed, axles removed:

Engines/trans/diff fitted to chassis, axle locations marked:

Holes drilled in chassis and rear end, stub axles will make assembly easy after the rest of chassis construction/painting:

We're assuming there's a very expensive set of 1:1 bevel gears inside that housing, along with locked axles.  There will be no rear suspension, this seems to be standard for LSR cars of this era.

 

 

 

 

[Harpo]

Rear end of the chassis is roughed in:

Profile view with chassis in correct position:

Test alignments to set wheelbase and see how much I can take out of the body width:

Wheelbase will be 191", track is 55", body will be narrowed about 9".  It would take some very special tires to handle the weight and speed, so I'm pretending they were available in 1973!  

 

Edited October 30, 2018 by Harpo

[Ace-Garageguy]

I'm kinda thinking with that much torque on tap, 300MPH is reachable. Consider this: in 1958, Mickey Thompson and Fritz Voight built a twin-engined (fuel-injected 392 Chrysler hemis) car that went something like 294 on the salt.

   Figure 900HP, 800 ft.lbs. torque, with a frontal area of around 13-14 sq.ft.

The 4-engined (Pontiac 389) non-supercharged first version of the Challenger I had no problem breaking 300, with more frontal area, around 15 sq.ft., around 1800 HP, and 1500 ft.lbs. of torque.

The second version, the 406 MPH car, had 3200HP and probably 2500 ft.lbs. of torque, but also had a huge increase in frontal area from the blowers sticking up out of the bodywork.

Your all-up weight is really no problem, because you have literally miles to accelerate. The high weight will help traction too, always an issue at high speed on the salt...which is why Thompson favored all-wheel drive.

Maybe think about narrowing the greenhouse as much as possible to still cleanly streamline the engines, but just barely, to further reduce frontal area.

This is, of course, all just cocktail-napkin engineering...but it sure feels doable.  

EDIT: As far as tires go, Goodyear built Thompson's tires at a cost to them of somewhere around $30,000. Derived in part from what they knew about building tires for jet aircraft, they were supposed to be good to 500MPH...and this was in 1960. By '73, somebody certainly could have built the large tires you need for this.

Edited October 31, 2018 by Ace-Garageguy

[Harpo]

2 hours ago, Ace-Garageguy said:

I'm kinda thinking with that much torque on tap, 300MPH is reachable. Consider this: in 1958, Mickey Thompson and Fritz Voight built a twin-engined (fuel-injected 392 Chrysler hemis) car that went something like 294 on the salt.  Figure 900HP, 800 ft.lbs. torque, with a frontal area of around 13-14 sq.ft.

The 4-engined (Pontiac 389) non-supercharged first version of the Challenger I had no problem breaking 300, with more frontal area, around 15 sq.ft., around 1800 HP, and 1500 ft.lbs. of torque.  The second version, the 406 MPH car, had 3200HP and probably 2500 ft.lbs. of torque, but also had a huge increase in frontal area from the blowers sticking up out of the bodywork.

Your all-up weight is really no problem, because you have literally miles to accelerate. The high weight will help traction too, always an issue at high speed on the salt...which is why Thompson favored all-wheel drive.

Maybe think about narrowing the greenhouse as much as possible to still cleanly streamline the engines, but just barely, to further reduce frontal area.

This is, of course, all just cocktail-napkin engineering...but it sure feels doable.  

EDIT: As far as tires go, Goodyear built Thompson's tires at a cost to them of somewhere around $30,000. Derived in part from what they knew about building tires for jet aircraft, they were supposed to be good to 500MPH...and this was in 1960. By '73, somebody certainly could have built the large tires you need for this.

Great information, thank you!  I was counting on the weight being no problem, but good to see it clarified.  I know the salt is soft sometimes, I do remember the Spirit of America taking an unscheduled dunking but as I recall that involved a brake failure. 

With all the components laid out, I find the body can easily be narrowed by 19", giving 23.6 sq ft of frontal area.  There's even room to narrow the greenhouse an additional 25", bringing the total down to 19.3 sq ft, so it looks like I'm good there.  

I don't know how accurate it is, but I'm using this page for calculations: Horsepower & Aero Drag Calculator 

   

[Harpo]

I've got the configuration pretty much sorted out.  188" wheelbase, seat and tanks up front, radiator (blue outline) angled under the greenhouse.  I'll add ducting through to the radiator, the driver's compartment will will be at hood level and just have a small windshield to peer out and keep her straight.  Next up is removing the existing front springs, extending the chassis, and fabricating the front axle.

   

Edited October 31, 2018 by Harpo

[Ace-Garageguy]

Without a doubt, one of the wildest racing machines ever conceived. Love it.  

[Oldmopars]

I love this. Very cool idea. It is a larger version of the 3.5L Plymouth Mini Cooper I just did. I will continue to watch this.

My only question so far would be about the fuel tanks. I know those Diesels will consume some fuel, but you are only going a few miles each run. Do you need that big of fuel tanks? Or, are they added ballast to put weight on the front tires for stability?

I would think that you could get by with around 30 gallons for a 10 mile run.

[Harpo]

1 hour ago, Oldmopars said:

I love this. Very cool idea. It is a larger version of the 3.5L Plymouth Mini Cooper I just did. I will continue to watch this.

My only question so far would be about the fuel tanks. I know those Diesels will consume some fuel, but you are only going a few miles each run. Do you need that big of fuel tanks? Or, are they added ballast to put weight on the front tires for stability?

I would think that you could get by with around 30 gallons for a 10 mile run.

Love your Mid-engine Mini, great weathering job!

The two tanks are 15 gal each by my calculations, so they're actually rather minimal.  I've considered adding more, since long distance runs were often done "back in the day". Nowadays we seem to concentrate on maximum speed, but for a long time 1/6/12/24 hour and 100/500/1000 mi/km endurance records were common. 

 Here's one of my favorites, MG setting a record in Class F for a 12 hour run in 1956, 141.81mph.  Fuel stops are allowed, but the car I'm building here would still need more than 30gal for a run like this!

 

[Jantrix]

Wait! I think I have found a driver for this monster.