The Dodge Challenger Message Board

So as not to hijack Dave's official Land Speed thread, how would we make an attempt at the wheel- driven Land Speed record? What would we need? What combo of engine, body, wheels, etc?

No right or wrong answers here, just a theoretical exercise (unless we form Team DCMB, and really go for it ). It was interesting to note that the top speed (measured over a mile) has only increased by 30mph since the Summers Brothers run in 1965. Should be a doddle then.

I assume the land speed record you are on about is for a naturally aspirated car?

I don't have a degree in mechanical engineering (or any meaningful qualification if I'm honest) but it seems to me that to get the high speed you need high gearing and for high gearing you need massive torque.

So big inches. Four 500 inch wedge engines like the one Eddie built might do it. Two pairs coupled together. Drive to the rear wheels only from two transmissions, via two driveshafts, two GV overdrive units, to a single axle with two locked diffs.

Cooling I would use the stock mechanical pumps plumbed into a common water system. Two radiators placed in front of the first pair of engines with air ducted from ??? (high pressure area - the nose?) and exit?? (low pressure area?)

I really have notthought this through. This was just quickly off the top of my head. So feel free to poke holes in it.

Looks to me as if Goldenrod still holds the unsupercharged record.

http://en.wikipedia.org/wiki/Wheel-driv ... eed_record

OOOPS!

No I was mistaken. I missed the Spirit of Rett streamliner near the bottom of that Wiki record table.

414.316 mph.

Goldenrod was 409.277 mph.

http://landspeedevents.com/blog/charles ... ech-sheet/

So the record we are setting our sights on here looks to be Group II, Class 11.

I don't think you could break a piston driven record with normally aspirated engines, I think you'd have to use multiple turbo diesels, see the torque the Ram engines are punting out already, mind blowing

Adrian Worman wrote:I don't think you could break a piston driven record with normally aspirated engines, I think you'd have to use multiple turbo diesels, see the torque the Ram engines are punting out already, mind blowing

Those two records ARE N/A piston engines. The record being held by a 1000hp single V8 powered car.

If you use a turbo or blower you are in a different class (Group I). So you would be breaking a different record to that set by Goldenrod and up against the REALLY big budget boys.

7500rpm should get us 436mph top speed with a 1.5:1 axle ratio and stock 727 gears with GV overdrive using the same size rear wheel as the current record holder.

The wheel they were using was only 24.5 inches diameter. If we had something taller in the wheel (that would take the rpm stress) it would be easier.

Good fun this bench racing init?

I was originally thinking 'anything goes' class (but driven through the wheels), but sticking to normally aspirated would present more of a challenge. Turbo technology is improving incrementally, so six months from now will probably produce something unthinkable 12 months ago. Which kind of takes the fun out of it.

So what say we go normally aspirated only, and see what we can come up with?

Team DCMB. Yeah Baby!

Dave, are you taking into account aerodynamics? I don't recall the math involved but over a certain speed (around 120mph -15mph0 IIRC) aerodynamics starts overtaking many other aspects of LSR competition ( and any high speed competition). And when you're talking the speeds necessary to what is being discussed, aerodynamics and air friction play a major part. (The torque doesn't hur either )

Yeah. We would have to factor that in. The forces go up on a logarithmic scale. When funny cars started going over 180mph some of them actually had the body collapsing at the sides.

You have to start taking into account of the aerodynamic centre of gravity rather than the static centre.

Four 600hp engines should do offer enough power. I was thinking driver at the front in a narrow streamliner shape, widening towards the rear to accomodate the side by side engines. They would be angled on their mounts a little to take up less space but how far you tilt an engine before oil in the valve covers becomes a problem I don't know.
There have been at least two Dragsters with 4 engines. Will have to find some photos of multi engined machines for you.

Where the body starts to widen you could have the cooling ducts for the two radiators.

This is the sort of thing you were thinking of I suspect Tim?

Now it is!

That's a thing of beauty, no mistake. Must say, the 4 engine design holds a lot of appeal. It's closer to the original Summer's Brothers concept, you get all wheel drive (probably an advantage on glass like salt), and presumably each engine is less stressed than if you tried to extract similar horsepower from a single engine?

It might hekp traction Tim but I think that would turn into a parasitic drag at really high speeds
I suggest some very high tech engine choice, how about 4 of the 7 litre V12's from the TVR Speed Twelve?
If I remember rightly those Al Melling designed normally aspirated engines were good for 800 horsepower even in 'street' trim........................ MONSTER MONSTER

"I suggest some very high tech engine choice, how about 4 of the 7 litre V12's from the TVR Speed Twelve?
If I remember rightly those Al Melling designed normally aspirated engines were good for 800 horsepower even in 'street' trim........................ MONSTER MONSTER"

They would certainly make an interesting alternative to the more conventional Hemi. Maybe we could nominate 3 or 4 alternative engine combos', then take a vote on the favourite?

For multi-engine setups look at the Unlimited Pulling Tractors here in the USA. This is a central USA dominated (read that as farmer dominated) motorsport. Pulling is all about torque. I haven't been following it much the last few years but back in the day five to eight engines was the norm. And these were all blown big blocks, Hemis, SOHCs, Merlins etc. Wasn't uncommon to see a tractor running 8000 hp.
What's even more cool is back in the 1970s these guys were running multiple RR Merlins, Allisons etc!!
For multi-engine drag cars, about the most famous was TV Tommy Ivo and his four-engined all wheel drive dragster! The problem with it, IIRC,was that it was never very successful. IIRC he could never get it to hook up correctly. I'd have to look it up to resfresh my memory.
Another thing to consider is budget. Do you build something that will last long enough to run or build something that will last long after the runs are finished? Building it to last would be more $$$ as opposed to building it long enough to make its runs. Cooling would be another critical aspect. A large torque-producing engine will most likely run cooler as opposed to a smaller twin turbo high tech engine (think EcoBoost). The aerodynamics would curtail a lot of possible cooling solutions also.
Dave, your idea of a narrow front going wider is already being attempted. Abeit in Lemans trim - the Delta Wind car. Now under Nissan sponsopship. That car has a lot of potential and I would think that it has some great possibilities in LSR circles. Would be nice if they tried it there sometime.

Well lets have a look at multi engine LSR cars over the years.

The earliest one I can think of is the 1927 "1000HP" Sunbeam which was the first car to break 200mph.

This car had two 22.44 litre V12 engines making 435hp each. Which of course adds up to 870hp. The "1000hp" thing was a publicity stunt.

They followed that up in 1930 with the Sunbeam "Silver Bullet" which had two V12 engines and single supercharger that in theory should have been making something like 4000HP. However it didn't run as fast as the previous car (186mph) and had a tendency to catch fire. The problem was the exhaust was too close to the inlet chambers and the heat was igniting the inlet mixture before reaching the cylinders.

In 1937 the six-wheeled 7-ton Thunderbolt averages 311mph using two Rolls Royce V12 supercharged engines producing 2,350hp. The following year, after some modifications, he did 347mph.

In 1947 John Cobb in the twin 1,250hp engine Railton-Mobil-Special went 403mph but the two way average was 394mph.

Now this gets interesting.

Mickey Thompson's CHALLENGER I.

Two pairs of 700hp fuel injected, Pontiac V8 engines sharing two superchargers. One pair of engines driving the front wheels and the other the rear. He set the record at 367mph in the year I was born. 1959. The next year Thompson fitted a rootes type supercharger to each engine for a total of 3000hp. He hit a top speed of 406mph into a 5mph headwind but problems and breakages stopped him setting any records.

In 1968 Mickey Thompson was back. This time in the Autolite Special. Two 427 inch Ford SOHC engines. The front one normally aspirated and making 810hp. The rear engine supercharged and making 1,260hp.

He did 425mph on the first run but rain stopped the return run.

1969 he was back for another try. This time 360mph on the first run and 442mph was reached during the second run but a chute failure stopped him short of the timing lights. The Ford sponsors pulled out after that and he had to give up.

Now here are the photos of the Summers Brothers GOLDENROD.

And the specs.

Nice bit of posting Dave, thank for that. It'll be a cold day in hell before I grow bored of looking at historical information like this.

Lessons learned from the above?

- Make sure your combination is reliable.
- Make sure your chute is packed properly.
- NEVER try and set a land speed record wearing pin- strip trousers.

Wicked stuff Daveman . ..........John Cobb was my absolute hero at infant school

OK then. I have changed my mind. Lets go for almost a copy of the Goldenrod. But I would still like the driver at the front.

The small cross section of the streamliner is a lot more important for aerodynamics than I at first realised. So is weight as these old cars did not reach top speed until well into their timed runs. So light construction is also important.

So 4 aluminium Hemis in a line. Fuel injected as in the original.
But driver at the front in a pointy nose to make it even more aerodynamic.
Aluminium frame for the chassis.

I think you could get a reliable 800hp out of each of those engines. We aim for 440mph.

Would be interesting to see how an inverted wing would compare to the pointy noses. The streamliners have a small cross-section but they all seem to allow air underneath the vehicle. That, I believe, is a big speed robber. Also an inverted wing would tend to suck the car closer to the ground, therefore effectively diminishing the frontal cross section, thus freeing up horsepower to propel the vehicle instead of overcoming air resistance.
Would be curious to see if any wind tunnel tests have been performed.

Another theoretical advantage of the inverted wing could be more interior room. Instead of squashing together everything (causing a temp rise due to closeness of heat-generating equipment, i.e. engines, cooling etc) the components could be placed to better operate as a group.

Down force = drag = limited top speed.

As speed increases downforce and drag increases.

This is why F1 cars open their rear wings to overtake. On the tracks with long fast straights they set up the cars with less downforce than on the tracks where there are more slower corners.

This is shaping up nicely.

Must admit, the idea of upping the current record with a Summer's Brothers- style car is very appealing.

Theoretically, if you built a streamliner to similar dimensions, and used modern materials and technology to make it lighter, and used modern technology to extract more horsepower (Goldenrod was only making 608hp/ engine, according to specs above), then all other variables being equal (air temp, fat driver, etc) you couldn't help be go quicker.

800- 850hp/ engine seems like a nice trade- off. Enough to up the current record, but still low enough for a well- built engine to run with consistancy.