Jim Gs SLURP Project Posting 8: Driving Red Home to Jim Gs Garage
This posting is one in a series. If you have not yet read the earlier postings in the series, youll need to, as this posting wont make much sense without having done so! Just do a search using the word SLURP.
In my last posting, you heard from Carter Gresham all about his trip driving Red home to Texas after buying him in Colorado. In this posting, Im going to describe my own interesting trip to buy and pick up Red from Carter and the drive home to Spicewood, Texas. It turned out to be a trip full of surprises.
First, when Randy and I arrived at the designated meet point,Carter was not there. It turned out he had had trouble finding the keys at the last minute, even though he had set them and everything else out the night before. Talk about a Freudian signal that he might not have really wanted to sell Red . . .
Then, after Carter and had exchanged all the required paperwork, and I was all set to go, I asked how much gasoline was in it, and did the guage work as well as it appeared to. Carter said it was about half full, but his dear wife Debbie, no doubt remembering the non-scheduled fuel stop in Colorado three years ago, advised that I fill it SOON like at the gas station just 14 miles down the road!
I had no trouble backing the truck into the street, but it sure seemed reluctant to go FORWARD. It turned out that Red had decided at right this moment that his parking brake release spring was too tired to carry on, and had obstinately declined to release the parking brakes. Again, talk about a Freudian signal, this time from Red. Once I realized what was going on, I simply assisted the pedal upward with my foot to the off position, and we were on our way!
In could see within a mile that this gas gauge was going to be less precise than the one on the SSR. I could see that because it oscillated, somewhat randomly, between about 5/8 full and 3/8 full. Apparently, there is no damper on the mechanical float in the tank. I began to respect Debbies advise.
The next revelation occurred when I got onto the highway. There was absolutely no sense of inadequate power, despite the fact that even mildly hotrodded as it is, Reds 261 cubic inch inline six cant possibly make more than somewhere near crank horsepower at MOST (stay tuned for the thrilling dyno test results in a later posting!). The reason that it felt so capable is simple: its a torquer. Peak power on a stock 1958 model year 261 like Reds would be only around 150 crank hp and occur around 4000 rpm, but the stocker also still makes 121 crank horsepower at 60 mph (2800 rpm with stock gearing).
The engine technically makes peak torque at 2000 rpm, but it also literally makes more than 85% of peak torque at IDLE speed. At the other end of the rpm scale, its still making 81% of peak torque at 4200 rpm, where GM terminated the dyno test .
Since the road was posted at 60 mph, and since Carter had warned me that 3000 to 3200 rpm was the maximum advisable long-term cruise rpm for the engine (considering durability, fuel mileage, and noise), I settled in at an indicated 57 or 58 mph and 3000 rpm. I was expecting other vehicles on the road to pass me, since I was going 5 mph under the limit in a state where everyone drive OVER the limit. But, strangely, no one did.
At the gas station 14 miles later, Randy asked me how fast I thought I was going and I told him 57 or 58. Randy chuckled and pointed out that the SSRs speedometer, whose accuracy has been amply verified by consistency with its tachometer, by G-Tech readings, and by a highway speed radar robot (dont ask), was indicating 65. Oops . . .
We topped off the gas tank on both Red and the SSR, so that we could do a side-by-side fuel mileage comparison for the trip home, and took off again. Very soon, we hit Highway 281, an undivided, hilly 70 mph highway that is 2-lane in most places for about 100 miles, and adds a lane on some of the steeper uphills, so that heavy vehicles will not delay other traffic. I kept Red at 3000 to 3200 rpm here (64 to 68 mph actual, but with Red modestly claiming only 57 to 61 on the speedometer), out of courtesy for other drivers, and made sure I moved into the slow lane on those steep uphills.
But again, strangely enough, almost no cars passed me on those uphills. After a while, I realized what was happening: Reds ample low rpm torque, coupled with his relatively high highway engine rpm (2825 at 60 mph), means that he doesnt even FEEL the hills that more modern high revving cars have trouble with unless they downshift. For comparison, my own SSR now has at least 130 rear wheel horsepower at 60 mph, but before I regeared, cammed, and supercharged it, it had less than 60 stock rwhp at that highway speed! Even with the automatic transmission, and assuming only stock versus souped up engine, Red has to have at LEAST 95 rwhp at 60 mph, and hill climbing is absolutely no problem for him.
The next surprise was the attention I was getting. Or, rather the attention that RED was getting (I was just along for the ride). Im used to getting a certain amount of attention driving my SSR, but that is NOTHING compared to the attention that RED gets! EVERYONE looks, and stares, at Red. A large number of the cars that did overtake and pass us, actually stayed abreast of us for as long as traffic allowed, while their occupants stared, pointed, grinned, and gave thumbs up approval. Shy drivers need not apply . . .
The last surprise was gas mileage.
Total resistance that a vehicles engine has to overcome on a straight and level highway is composed of two parts: road friction and air resistance.
The power needed to overcome road friction is pretty much a set percentage of the vehicle weight multiplied by vehicle speed, and becomes progressively a smaller percent of total resistance, compared to air drag, as speed increases. At 65 mph, it represents only about 1/3 of the total power that a Chevrolet SSR needs to expend to cruise.
The AIR resistance is the big factor, and its magnitude depends on two things: cross-sectional frontal area of the vehicle, and the coefficient of drag for the vehicle (i.e. how streamlined it is in total), and unlike road friction, power required to overcome it goes up with the CUBE of the speed. At 65 mph cruising, 2/3 of the total power expended by a Chevy SSR goes toward overcoming air resistance.
On a hilly road, things change a bit. The EXTRA power required to climb grades (beyond what is already required to cruise on level ground) is proportional to the vehicle weight. And, while a vehicle recovers some of that power when descending hills, the recovery is very imperfect, so hilly roads tend to hurt fuel mileage a lot. Heavier vehicles are at a relative disadvantage on hilly roads.
If you print out Reds frontal profile, make a grid, and count squares, as I have done, you would find that Red has about 30% more frontal area than an SSR (and 43% more than a Corvette!), and it is obviously less streamlined as well (Reds windshield for example is pretty upright compared to that of an SSR, and Red has no streamlining cargo bay cover!). Red weighs about 30% less than an SSR, BUT since the percentage of total drag due to road friction, and the losses due to hills, are smaller than air resistance losses at highway speeds, the ruling factor is by far the fact that Red is pushing 30% more cross-sectional area down the road. Red is sort of a high speed refrigerator heading down the highway. My hopes for gas mileage were therefor not great to begin with.
They got worse as I considered the other disadvantages that Red came to the mileage table bearing. The SSR has an onboard computer on board doing calculations of how much fuel to squirt into each cylinder, and how much ignition advance to apply, as often as 100 times per second, based on changing load, temperature, etc, and based on reliable multiple inputs it gets from multiple sensors within the engine (e.g. rpm, coolant temperature, knock sensors) and outside of it (e.g. mass airflow meter, ambient temperature, throttle setting). The SSR also squirts the fuel for each individual cylinder directly to the intake port right near the intake valve for each cylinder, ensuring it all gets to the intended destination. Red only gets a direct prod from my foot (via the accelerator pedal), and depends upon TWO 50 year old mechanical Carter-Weber carburetors to work in unison, based on a homemade linkage, to dump roughly the right amount of fuel and air into a log type intake manifold with far from ideal subsequent distribution to the 6 cylinders. Just thinking about this as I drove, my mileage expectations sank further.
But Red really surprised me.
When we reached Marble Falls, the last town before home, we carefully filled up both the SSR and Red. The SSRs trip computer declared that it had achieved only 16.8 mpg on this trip segment of almost 130 miles, thanks to the high speed under hilly and windy conditions, and the frequent small towns we had to pass through at city speeds. Reds mileage, carefully hand calculated (no onboard computer  ), came out to 15.2 mpg. For an engine running at 3000 to 3200 rpm, with two hand-synchronized 55 year old carburetors, running its power through a 55 year old fluid coupling automatic transmission, pushing an upright refrigerator through wind on a hilly road, that is pretty impressive.
Overall impressions from my first road trip with Red:
- Theres more power here than the specs suggest
- Red may be 53 years old, but he performed reliably without incident
- Cab noise level is definitely higher than in the SSR 
- Leaf spring suspension is not that bad
- Red is modest, claiming a MUCH lower road speed than he is actually achieving
- Gas mileage was surprisingly good
- Dont even THINK about traveling anonymously when youre driving Red
Next posting, well take a look at a very personal side of Red; his actual weight. I can see him blushing through his red paint.
