Tag Archives: technical stuff about building cars

Spitballing other gas tank options for the TGS2

I have been thinking about other places to put the gas tanks than inside the body with me.

One place they will have an aerodynamic effect is between the wheels to fair them in aerodynamically and keep the undercar and top of the car separate aerodynamically. This design would basically be a wall instead of a fence keeping the high-pressure flow constrained to the top and not letting it spill over into the low pressure flow under the car, and also clean up the wake from the tires. This will increase downforce and reduce drag at freeway speeds which will help the gas mileage. Now the bad parts, the tanks will be pretty vulnerable stuck out on the far edge of the car even if I put a protective cage around them. Also putting the fuel out there does bad things to the polar moment of inertia, which is a measurement of how much energy needs to be expended to change direction of the car. The further away the tanks are from the center of gravity the higher the polar moment and the harder it will be to make sudden changes in direction. I could make this work for me in setting up the car for highway use where a high polar moment is good for stability, and run pretty much empty tanks for racing and a low polar moment for a car that changes direction almost telepathically.

A quick punching of numbers on the calculator app gave me over 700 pounds of E85 for near coast-to-coast unrefueled range (2900 miles), so I don’t need to use the entire volume available for fuel, some could be empty space for strictly aero purposes, or the tanks partitioned for ballast use to make the polar moment higher when I want it to be high. But with the tanks out on the edge I’m still stuck with the vulnerable in a wreck scenario. Now the other setup with the tanks inside the body with me but outside the frame gives me a low polar moment with tanks full and even lower with race levels (almost empty) than the outrigger tanks because even the empty outriggers have some weight and so does the support structure even without crash bars.

Something else that occurred to me was that I could use a 1 gallon fuel cell as a surge tank when in street mode and the total fuel capacity in race mode. On the street or even in race mode there wouldn’t be any time that I would drain a 1 gallon tank. In an autocross the longest courses I would run are less than 2 minutes long, while on the street even frequent stop-and-go traffic would not use fuel faster than a low-pressure pump could refill the surge tank, or gravity if the level in the main tanks was higher than the surge tank. There are several models in the current JAZ catalog from a quart to 3 gallons capacity set up for use as a surge tank so I don’t have to design this bit from scratch, just buy and attach the plumbing and drive it, NBD. And looking at the catalog I could easily stuff 2 10 Gallon cells per side into the outriggers without much effort. The only thing that might make it tough is the 9″ width getting towards the front of the enclosure where the tire it’s chasing is only 7″ wide. But a 9″ wide tank can fill the wake just as good as a 7″ one, if not better.

OK then, the fuel system is 4, 10 Gallon fuel cells with foam, 2 per side inside the wheel fairings on the outside of the car with the low pressure fuel pumps mounted between the tanks on each side, connected to a 3 gallon Pro Mod cell with foam as a reserve/surge tank feeding the high pressure injection pump. This gives me a system with enough range to get to El Paso from Dallas with reserve for adverse winds and also use crash-resistant containers to prevent leaks in case of a wreck. Also, dividing the fuel load between several containers limits the amount of fuel spilled in a wreck. Still subject to revision in case of a different donor vehicle, because changing the location of the engine changes everything else, and changing the donor vehicle can change the end of the vehicle the engine is placed in.

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Designing gas tanks instead of sleeping

Just because I can’t get words out because brain not working right doesn’t mean I stop thinking. The exact opposite happens.

I was trying to come up with a frame that would put me on the driver’s side of the car and still be stiff and that I could fit inside the body without chopping the body into little pieces and hanging a couple of hundred dzus fittings on the frame to attach the body. Physically can’t be done. So I’m back to sitting in the center of the car and the gas tank is now sitting on either side of the frame instead of the passenger side of the interior. The fun part is now I have to design a pair of fuel tanks that literally have no parallel sides and figure out how much gas (E85) I can carry between them.

First things first I measured the body to find out what space I had to work with. The major design constraint is the sides of the tank are going to be flat pieces of steel for ease of construction, so where the curves in the body make that impossible defines the volume of the tank. First constraint is where the back of the body starts to curve up from the floor, which defines the length, 41 inches from the inside of the firewall. Second constraint is being able to slide the tanks in from the top without removing anything, so the tanks have to clear the dash and the top flanges of the body and the bottom of the dash is 10.5″ from the inside of the firewall, leaving 30.5″ as the length of the tanks. Measuring the inside of the body at the floor gave me a width of 33″ at the front and 34″ at the back. Measuring the same locations at the body top flange gave me 37″ at the front and 44″ at the back, and a depth of 19″ inside the body flanges. Now not all of this volume will be available for fuel storage, I’m going to occupy a large chunk of it, 27″ down the center front to back.

This leaves us with two methods to determine the available volume, find the total volume and subtract the volume taken up by the frame around the driver, or remove the space taken up by the frame around the driver from the measurements and calculate the space left over. The easy part is the volume occupied by the frame around the driver 27″ wide by 30.5″ long by 19″ deep, or 15646.5 in3. The volume around that is a bit trickier to calculate because the space is a trapezoidal polyhedron, and the volume is the average area of the top and bottom times the depth. The quick way to calculate the average area of the top and bottom was to average the top and bottom widths on both ends, by adding them up and dividing by the number of measurements (4) and multiplying by the length (30.5) and then the depth (19) to determine the total volume. Subtracting the volume occupied by the driver and frame leaves 25.4 gallons for fuel. Which is not enough to get across the E85 barrens of west Texas and NM at the projected fuel economy for the vehicle. That means I need to make the tanks bigger or find room for another tank. Now one way I can make the tanks bigger is taking less space for the frame (and me) but it is late and I’m getting tired and unmedicated brain is not thinking good and wants to sleep.

Too much in my head, back to the car build

Yesterday was too much in my head to write properly, today I’m in my car instead.

As I was refining the design in search of further levels of performance I was getting further away from its identity as a Model T-based hot rod, to the point that it was no longer identifiable as based on a T-bucket. I had to get back to something that looks like a Model T, that looked like a hot rod. So the radical cockpit-in-the-nose design had to be shelved in favor of driving from the driver’s seat of a car that looks like a hot rod. It will still be a single-seat car with a huge fuel tank in the middle of the car, I’ll just be sitting in the normal position for a street car in the US. That means where the engine used to go will be available as a small trunk for carrying clothes and toiletries for driving to the races. It also means that I can tweak the aero in the nose for better cooling, less drag, and more downforce at the cost of less volume for clothes. Now if I was really bucks-up I would make a fuel tank to match the available space in the nose and carry luggage on the passenger side of the car except I really want the fuel load in the middle of the wheelbase. Since the fuel load is pretty much the largest variable in the car equation it makes sense to keep it as close to the center of gravity of the car to minimize the changes in handling on long trips. I mean we are talking more than 210 pounds of fuel from full to empty sitting next to the driver (me). The one thing that concerns me is I’m sitting next to more than 30 gallons of gas! OK it doesn’t concern me that much, just a little. And I’ll probably put the battery over on the right to balance out the lard butt in the driver’s seat when racing with the gas tank mostly empty. The tricky part is getting gas in the tank without overflow going all over the interior making the driver stink of gas, or E85 as the case may be. I have never smelled spilled E85 as the nearest station is outside where the bus goes, and I don’t make a practice of hanging out at gas stations without a bus stop. I keep checking and I don’t see any near me that also sell E85. Closest one with a bus stop is over in Richardson.

And you know what, I’m all written out now that I’m unmedicated. I really can’t wait until I can start taking the new med that doesn’t have the sexual side-effects but still keeps me from being depressed.

I’m back at the keyboard

And I have been applying the data from scaling the picture to checking the fit against the actual body sitting in the living room. The engine will fit with both ends hanging out by about an inch from the bottom, or about 2″ on the left only if that’s the way it balances out, or whatever way it works out. Or, thinking again, there is enough room to fit the whole mess inside a stretched pickup bed . It will be wide enough but I will need to stretch it to fit the front-to-back. Then I can sit inside the actual bucket instead of a pod out in front of the body. It will still be center-steer, probably with my feet through the “firewall” of the original body.

The trick will be making sure the front tires don’t hit the body at full steering lock, and finding someplace to put the fuel tank or tanks. If I can get enough room I might be able to stuff the gas tank behind the driver like on the pod in front setup. The only difference is instead of 34″ width to the axle for the footbox I’ll use the 26″ firewall width for the footbox. Still a ton of room for my brogans or combat boots, or my usual walking shoes, and the steering shaft. The critical thing on the front is keeping the tires out of the bodywork at full lock, and turning the tires parallel to the axle gives me 34″ between the tires. So if I keep the firewall on the body far enough behind the axle then the tire will not hit the body at full steering lock, and there will be room inside the body behind the driver for the 32 gallon fuel tank.

I might have to cut the back of the bucket off to get the engine and fuel tank in the available wheelbase. A bucket has 100-102″ of wheelbase normally, they run from 87″ to 116″ historically for buckets made from old passenger car frames, my bucket will be 100″ even. As mentioned in an earlier post, with the 32 gallon tank all the pieces and I take up 97″ with no extra space between the bits for bulkheads, which means I can use the same 1.5″ round tubes for the bulkheads and crossmembers that I plan on using for the frame rails.

While I was letting the cat out for the night I tripped on where the cats had wrinkled up the hall runner in the dark, and I think I broke a toe. It hurts constantly, and gets really bad when I touch the side of the toe, like really intense. The toe is swelling up and I guess I will find out in the morning if I broke it if it’s all black and blue. This really sucks because I need to walk to the store to get a lottery ticket later and that will be difficult with a broken toe.

Update, it’s a few hours later and I definitely have injured the toe next to the big toe on my left foot. As in swollen, and black and blue, and very painful and sensitive to touch.

It turned chilly today

I had to go outside today, and it was a mite chilly, 49°F chilly for a high temperature to be precise, with a “feels like” of 43 when I was out in it. How chilly is that? I wore long pants to cover my knees for the first time since winter, but I forgot to grab a belt out of the closet and spent most of the return trip trying to keep my pants from falling off. That was about a mile walking with one hand holding up my pants.

The reason for the trip was I needed to get bus fare for a meeting tomorrow, and a lottery ticket. Unfortunately instead of the annuitized $18.25 million payout the ticket was for the cash value option payout of $12.5 million. So if this blog goes silent after Monday you’ll know I am taking time to manage my finances prior to accepting the jackpot. The meeting is the artist of a web comic I read, Not A Villain. I try very hard to support the creators of the entertainment I consume, even if it’s only clicking the ads on their sites.

On other subjects this blog has become known for, I went old-school to scale up that picture of the engine and transaxle and this time I found the assembly to be 36.1″ end-to-end as it sits sideways in the car, and about 2″ of the transaxle will stick out the driver’s side of the body if the CG is really on the line between the silver and grey on the forward engine mount. The accessory drive will be just inside the confines of the bucket body, and just clear the bottom frame rail.

And I still have stuff I need to do before I go to bed, so this post has to end now.

That was a long walk

Yesterday I made a 3.25 mile walk to measure an oil filter at Auto Zone so I can scale this picture and find out how much engine or transmission is going to hang out past the body.Now I can measure the oil filter and see how much wider the engine is than the bottom of the body.
That oil filter is 3.8″+/- a few thousandths in diameter, so the assembly is 36.25″ wide. ?WTF? It… almost fits inside the body. I could widen the body by 2″ at the back, and just fit everything inside the body. I won’t, because in order to get the engine balanced it has to be offset a bit so that one end or the other will stick out, but the rear of the frame doesn’t need to be widened to catch the left and right engine mounts. Well, maybe a bit, but nothing like what I was anticipating.

So, anyway I was going to talk about the walk. I stopped on the way back to buy a lottery ticket (I didn’t win) and took the back way from the parts store away from the 50 MPH speed limit (actual traffic 60) main road/state highway the parts store sits next to and through a residential neighborhood or 2 to get home. Naturally this added to the length of the return trip but not by much in spite of the added turns. Maybe a quarter of a mile extra? Something like that. Anyway for my metric readers that was just a few meters over 5km round trip. The weather could hardly have been any better with 78°F (25.5C) and sunny with a nice breeze that never quite managed to blow my hat off. It was a nice walk except for the length, which was a little much for a zombie like me. Back when I was younger, like last year, that would not have been that big a challenge. Sure I would complain about it, because I always have to complain about something, but not a challenge, more like an annoyance.

Moving on to really random crap, I was thinking about a Flugtag craft for the next time the Flugtag comes to town, because I was in bed and couldn’t get my brain to shut up and let me sleep, again. What I was thinking most about was adding a pedal-powered propeller and how to use a standard bike chain to drive the prop. What I came up with was a crown gear to mesh with the drive chain on the propeller shaft, and instead of a standard sprocket a grooved pulley for the chain to ride on and an idler pulley to both take out the slack from the chain and to make sure no more than 2 teeth from the crown gear engage so the chain isn’t tweaked sideways. The prop would mostly be a glide extender rather than actually flying the plane. The plane would be based on the canard version of the Icarus 2 biplane hang glider from the ’70s, because it was light and had a lot of wing area to fly slow. The canard version was made to get more pitch authority to allow for pilots that were too light or too heavy for the standard Icarus 2.

Having difficulty doing a post ATM

Yesterday was a complete flop for pretty much everything as I tried to catch up from spending pretty much the entire day playing Shadowrun on Sunday, with a needy (and kneady) cat in my lap most of yesterday. I have decided today is Bean Day, so the crock pot is full of simmering vegetarian goodness, and I’m caught up on everything except posting to the blog.

Some time this week I need to wander by an auto parts store with my calipers and measure the oil filter for my engine so I can scale that picture of the engine, since it doesn’t look like I will have access to my donor vehicle any time soon. The current possessor of the minivan hasn’t shown much inclination towards delivery and until I can find an engine hoist somewhere I don’t have much I can do with it if I had it. But once I know the diameter of the oil filter (which doesn’t seem to be a common piece of data) I will be able to scale the picture I have of the engine and transmission.
I was going to use the valve cover reference, but the oil filter is probably the best.
That grey and silver thing to the right of the oil filter (the white thing on the front of the engine) is the forward engine mount and roughly on the CG of the engine/transmission combined. There’s another one behind the engine in this picture and they are supposed to carry most of the weight of the assembly. What I have to determine is how much of the accessory drive and transmission are going to stick out from the bottom of the body. That measurement will determine where I put the bucket body in relationship to the rear axle and engine.

I was also thinking about things like the engine cover and the driver compartment. These will change depending on where the bucket part of the body sits in relation to the engine if the wheelbase stays the same, and what I really want to do is keep the wheelbase as short as possible. Because of the physical size of the engine and the fuel tank and yr fthfl srvnt in the driver’s seat about the shortest I can make the wheelbase is 97-98″ without reducing the “ferry” range of the car. Since I plan on converting the engine to full-time E85 consumption and there is a lack of E85 west of TX to CA I have to either detune the engine for 91 octane premium gas or buy a really big gas tank to bridge the gaps between stations. The limitation here is once the compression ratio has been raised to use all of the antiknock of E85 the tune to run 91 premium is pretty gutless and uses more gas than if I could run E85.

And I have been researching the costs of reprogramming the factory computers to work in the TGS2 vs using a standalone controller that has to be programmed, and the costs are shifting back in favor of the standalone, but only just. Just about any tuner in town can program a MegaSquirt controller, and I can do the MegaShift transmission controller by myself with the free software, but the 22YO factory computer is fast becoming a specialist-only orphan that requires a cost premium for programming that exceeds the savings of using existing equipment. One thing I’m being told is the software to reprogram the OE controller is no longer available or that the version available will not run on current laptops. I’m more inclined to believe the latter statement is the actual truth, especially legacy code like you would expect for a 1996 ECM. I mean when the controller was built Win95 was replacing 3.2 and laptops were the equivalent of tens of thousands of today’s dollars and people using them had to have mobile computing. The laptop I’m doing this post on was $200 after tax as a point of comparison, and I’m using it because it’s faster than my old desktop. So, it’s extremely likely the software is for a version of Windows that is no longer supported by Microsoft.

More later.

Groceries have been purchased

And we are stocked up on milk and PopTarts. Big deal of 2 gallons of milk free w/purchase of 4 boxes of 12 count PopTarts. Now we have a gallon in the freezer and I’m switching back to coffee in my milk in place of the iced tea I have been drinking since August. Also we have about 2½ pounds of candy to give away pretend we don’t have for Halloween.

I mentioned in yesterday’s post I had pretty much used up my hand downloading pictures from eBay of that race car chassis T Bucket that I had found when searching for a picture of something else. Don’t forget to mouse over the picture to read the description.

Repeat from yesterday

That's a big deck and spoiler to go with that wing

Look at that 5 inch coilover on the rear axle

There's ample room for the passenger.

They widened the heck outta that Speedway body!

Looks like a polycarbonate top skin to show off the internal structure of that wing.

He never centered the engine, it must have been heck getting the car balanced to make right turns safely.

Well he has plenty of ground clearance.

I assume this is the e-brake caliper bolted to the front of the rear axle.

Passenger seat is cozy.

Another view of how much the engine is still offset. How on Earth did he ever get the balance right?

A better look at how much the body was widened and how far the engine is offset. The distributor on a SBC is slightly to the right of the center of the engine and this one is slightly to the left of the center of the body.

WTF are those shocks connected to?!?

 Five inch coilover mounted behind the axle, plus some kind of surge tank next to the fuel cell. Battery also visible in front of the axle, and that's what the Wide 5 hub looks like.

That's one reason to move the engine over to the right, then you wouldn't need to put 4 U-joints in your steering shaft.

This series has actually given me food for thought on the engine and body install on the TGS2. Cut the back of the body wide enough to fit over the engine and let the transmission hang out the side behind the body so it won’t need a cutout and the body line can remain. That would move the axle centerline just in back of the rear of the body so the suspension can travel without having to cut the side of the body. Lots of room for the frame to catch the engine mounts. Make a fake P.U. bed from HDPE and faux woodgrain the surface.

Gotta go pick up refills on my meds

Yep, I’m outta happy pills, although in my case it should be “slightly less unhappy” pills. Because while they are effective they come with a buttload of side effects that work against their intended purpose. In my case engaging in sexual activity is highly beneficial in countering my depression, and one of the side effects is an inability to do that. And that inability is not gender-specific, it works equally well(?) against females as it does us guys. But without is worse than with even with the side effects, so whatcha gonna do? Be a lot depressed without or a little depressed and also unable to have sex with? I know my choice.

As always, getting back to the possible variations of the TGS2, I discovered there is no factory available manual transmission for the Pentastar V6. That means the only transmissions I have to choose from are the 845RE for a front engine bucket, or the 62TE for a mid engine bucket. A manual would require making a flywheel to mount a clutch and also drilling the crankshaft for a pilot bearing, then making a bellhousing to fit the bolt pattern on the back of the block that also fits the choice of transmission. While not impossible it does exceed my fabrication facilities.

Some good news on the TGS2 front I found a picture I can use for designing the rear frame if I can find the length of the valve cover as it is a straight-on front view with the mounts visible.
See, I can scale this with knowing the length of the valve cover and know if I need to build a funky cover for the transmission.

Or I can just find the size of the oil filter and scale from that, or use both and get really close to reality.

More observations from the State Fair of Texas

Well here’s another snippet. I finally got to see a Pentastar V6 in the wild, installed in a Charger base model. I didn’t have my phone with me or I would have shot some pictures, because there were some things about the installation that I wanted to show. One thing in particular was that I could see the carpet of the Automobile Building looking at the firewall and transmission at the back of the block, because the 8 speed automatic transmission is just that small. Too bad it weighs almost as much as the engine it’s bolted to.

To get technical the Pentastar comes in at 326 pounds. The 845RE transmission weighs in at 198 pounds. Still only 524 pounds for 305 HP with a flat torque curve from 1000 to 6200 RPM mated to an eight speed transmission with extremely low parasitic drag, or about 20 pounds less than the base 290 HP 350 SBC crate engine without a transmission.

And my hand is acting up again, so this is the end of this post.