Tag Archives: technical stuff about building cars

No NASCAR race, and trying to rain here

No race to watch on the flat screen, and the weather is threatening so I can’t go for a walk. That means I have to post something here or go crazy. Going crazy is no fun, and I think you have figured out by now what choice I made.

On really good thing about the Pentastar for the Sprint-T is its extremely short length. There’s 43″ between the firewall and the centerline of the front axle on the Sprint-T and allowing for movement the steering linkage is 7″ behind that so 36″ from the firewall to the effective limit on the space. There’s a 3.5″ thick radiator to leave room for and a 9″ long steering box with a steering shaft that has to snake around the radiator, that goes between the radiator and the axle. Measuring the space from the part where the Pitman arm bolts to the rearmost part of the box as installed on the car and adding the working length of the Pitman arm (7″) I get another 12.5″ between the steering linkage and the radiator leaving just 23.5″ unless I put the radiator over the steering box like they do on the Speedway T-Bucket kit. Putting the radiator in the space between the front of the box and the steering linkage solves a lot of steering issues at the cost of raising the CofG slightly, but the radiator is only 19″ tall and there is literally 27″ to put it in. Mounting the steering linkage below the axle leaves even more room for the radiator in front of the steering box because the radiator can go over the linkage and still leave room for the axle to travel up and down. At this point in the design the radiator is a box that is 26″ wide by 19″ tall and 3.5″ thick that can be moved back and forth and up and down until room has been found for everything else. Anyway, the engine is a 20″ box in front of the firewall that leaves 16″ for everything else. And here you are reading in real time my thought processes as I build the front end of the car.

Recentering my thoughts, there is 16″ between the steering linkage and the front of the engine, the problem is the steering box and the radiator are trying to be in the same bit behind the axle. I could put the radiator on the right and the steering box on the left and have room for both. The steering box is 4.5″ from the mounting face to the right side of the box, 5.2″ total width, and I have 34″ of width to play with behind the axle, 17″ on either side of center. That means I could stuff a 28″ radiator in the car and still not hang out past the frame rails/4-bar if I put the radiator next to the steering box. If I choose to slide the radiator between the steering box and the steering linkage then I have more room for radiator width, but only just, and the radiator outlet would have to be passenger side to prevent interference. The widest radiator I can get a passenger side outlet at the places I’m looking is 31″ which is the inside to inside width of the bottom frame rails when I build to a width of 34″, serendipitous isn’t it?

And it’s time to check e-mail and get ready for bed.

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OK I scaled that picture

And that is one tall engine, 29.25″ ±. And about 27″ wide. That means while it will fit nicely between the frame rails that are 27″ inside to inside it won’t fit under a hood that matches the contour of the firewall at 22″ tall. Heck, it’s more than 2″ taller than the entire 27″ tall body, and that’s not even counting the crossmember that needs to go somewhere near the bellhousing to triangulate that plane of the frame. Even without the rather tall intake manifold the engine is 23″ ± tall to the cam boxes on top of the heads, which are also 23″ wide.

This is doable, but I’m going to have to put the driver up a bit to see over/around the engine, and the hood is going to look funny sitting higher than the rest of the body. Possible workaround would be to mount the body higher over the bottom of the frame instead of just on top of the bottom rail, while keeping the driver in the same location inside the body with the seat bottom 3″ above the bottom of the body. This will raise the driver 7″+ in relation to the frame. This is not a good thing from a handling perspective as the driver is one of the heaviest items in the car and needs to be kept as low as possible. But a car you can’t see out of forward is not safe to drive even on a drag strip, so I guess the only choice is raising the body to raise the driver’s eyeline above the engine and put the floor at 11.5″ below the seat. Now how to raise the body 7″+ above the top of the bottom frame rail without adding too much weight to the frame? Since the body is not structural in this car, maybe some thin aluminum structure between the frame and the body, or dropping everything the 7″ and making a bellypan to cover the bits. No that part wouldn’t fly as I wouldn’t have the frame to protect everything should I run over spike strips and get 4 flat tires or as it is put in the original design spec nothing below the bead of the rims except tire at normal ride height. But raising the body does improve the space for people as the driveshaft tunnel would be dropped below seat height, making the possibility of a passenger bench seat next to the driver’s race seat for taking someone to the races or on a ride-along at the race.

I guess I could get someone to print up a manifold that drapes over the camboxes on either side and get a smaller vertical profile that way, and maybe even free up a little horsepower without having to raise the body if I get the top lower than the bottom of the windshield at 24.5″ from the bottom of the body, but that still requires a funny-looking hood that sticks up above the top of the firewall. Not to mention the throttle bodies hanging off the sides of the engine, that would stick out the sides of the hood.

And I really should link to the source of those pictures I have been scaling from in this forum thread . Thanks to myduster360 for starting this thread with the build.

Interesting changes as new technology is applied to old engines

I have been reading articles, and watching YouTube videos, about people putting throttle-body fuel injection on what are now called “Traditional V-8s”. The goal is better fuel economy while maintaining or improving performance. And what they are finding out is that the parts they used to use to get fuel economy with a carburetor don’t work with fuel injection. And also it has been so long since I worked on cars with carburetors that I forgot how to spell it.

Anyway, theory of operation of a carburetor is they suck. Literally, they work by drawing air through a venturi, which creates a lower than atmospheric pressure that pulls fuel from a small chamber inside the carburetor through a metering orifice called a jet, that is then atomized by the airflow and sent to the intake manifold and into the engine. Because of physics explained by Bernoulli’s Law, the faster the air is moving the lower the pressure inside and the stronger it sucks fuel into the manifold, and because our monkey brains won’t stop trying to put 5 pounds of stuff into a one-pound rated container, compromises had to be made in engine design. Since only one cylinder at a time can draw on the carburetor engineers made intake manifolds designed to only use ½ of the carburetor at a time.

dual plane intake manifold

Now we could literally get the same performance with half a carb used all the time, but like I said, monkey brains. Anyway, because of compromises to split the engine in half so that succeeding cylinders draw from opposite halves of the carb, mixture distribution gets moved down in priority by actually having fuel mixed with air. This means that when you use a throttle body fuel injection on the existing dual plane fuel economy manifold, you get an engine that runs like crap because of incompatible fuel delivery methods. You get some cylinders that get too much fuel and some that don’t get enough and maybe one or two that are right but only if you’re lucky.

Now the thing about single plane manifolds is they get all the fuel and air through just one hole in the top, or several holes that are connected inside, so after that they try to get the same mixture of fuel and air distributed to all the cylinders in the same volume of air distributed to each cylinder, so that each cylinder makes the same power and the engine makes as much power as possible for the amount of air it is consuming.

single plane intake manifold

side by side in the wild

The thing is single plane manifolds were generally considered race-only equipment, not suited for street applications and most definitely not for fuel economy on the street, but EFI is changing all the rules. Since fuel delivery is no longer dependent on airflow through a venturi it becomes more important to make sure cylinders all get the same amount of air mixed with the same amount of fuel, to all make the same amount of power so they use less fuel, and don’t just dump it out the tailpipe unburned. And in spite of initially being designed as race-only, with EFI they become the preferred application for street fuel economy. With EFI the Edelbrock Victor Jr. becomes the preferred street performance manifold over their RPM Air Gap dual plane, simply because it’s physically impossible to get equal mixture distribution with EFI from a dual plane manifold. With a carb you could never get decent street performance out of the Victor Jr. manifold because the intake velocity would not pull enough fuel from the carb or atomize it properly. Note in the links the RPM range for the manifolds when used as intended with carburetors, and then realize with EFI that doesn’t apply. That is what modern technology does when used properly. It makes ancient engines run like modern economy engines, almost. And even Edelbrock’s EFI kit comes with a modified Victor Jr. manifold. Notice I have no relationship with Edelbrock other than having installed one of their manifolds on an engine about 35 years ago when I was racing and working on race cars.

Well, that was fun

The auto racing season is underway. The 40th Advanced Auto Parts Clash (originally the Busch Clash) ran at Daytona this afternoon (congrats Brad Keselowski on the win) and as I type this the semifinal rounds of the NHRA Winternationals are live on the tube flat screen. I have never been a drag racer, but they are fun to watch. As an engineering problem the physics are fascinating. The ultimate goal in drag racing is to reach the finish line immediately after the light turns green on the start line either 1320 or 1000 feet away, driven by the wheels in most classes. The chemical and physical bonds between the tires and the track, the thermodynamics inside the engine as fuel is turned into power, and the mechanical transmission of that power to those bonds at the tires, that to me is fun.

SCCA Solo racing is drag racing with left and right turns, so there is some overlap in application to my kind of auto racing in terms of execution but almost nothing in engineering. Drag racing has no lateral acceleration as long as everything runs right as shown when Brittany Force wrecked in the first round of Top Fuel. The word is there will be a report from the hospital at 0800 Pacific on her condition. I sincerely hope she will be OK. For a sport so embedded with fossil fuel use and abuse, there are a surprising number of bicycles in use in the pits and elsewhere in drag racing, so some of Them are really Us.

Brain shutdown thoughts have been on the fact I haven’t included the mounts for the rear springs and swing arms in my plans for the Sprint-T frame. They have a specific place they have to be because the swing arms have a fixed length and connect to something that has to be in a certain place, and they have to be braced in at least two directions so the rear axle doesn’t move around and steer the car from the back independently of what is input at the front. Which is the reason why I didn’t design in roll steer for the rear suspension, because roll steer becomes rear bump steer when you’re just driving down a bumpy road. The slight performance advantage possible racing is more than offset by the possibility of losing control racing or driving on the street. So, the swing arms are level at normal ride height, preventing roll steer or rear bump steer.

And the cat is trying to sit on the laptop so I guess I’m finished.

I need something that will let me turn my mind off

OK I had another situation where I saw something on the internet that caused my mind to run around saying “This is perfect! This will fix all my problems!” and happily run rampant as I try to sleep. What started this was Cleetus finding a Renli 4X4 with nothing except the front and rear diffs left of the drivetrain. A little research tells me those differentials have 1:1 gears and are purpose made to turn a transverse FWD engine and transmission mounted longitudinally into an all-wheel drive drivetrain. And guess what I have with the Town and Country donor vehicle?

I could regale you for pages upon pages of discarded concepts and wild-assed ideas that I came up with while trying to get to sleep last night, and I still haven’t decided yet what I want to do. If I go with the AWD that destroys the sunk costs of the parts I already bought and/or built for the RWD version I have been working to build all these years. Basically the only thing I could use would be the fiberglass body, the windshield posts, and the steering wheel. All the suspension parts would be essentially trash as they couldn’t be sold for as much as half what they cost, especially the custom front axle and the steering parts. That loss would come to about $500 plus my time and labor preparing those parts for installation. In the grand scheme of things that’s not a lot of money, but it represents a ton of hustling for a buck here and a buck there to accumulate that money, like the job that makes $6/month, times a lot of months and a ton of other hustles like it that made $1 and $2 there, scraped together and hoarded to get me as far as I got so far.

Conversely I solve a bunch of problems with weight distribution and tire sizes by getting the mass more forward and centrally located. The Plan is mount the engine and transmission in the passenger side of the body and squeeze me in as best I fit on the driver’s side and all the main masses are right there in the middle of the car, engine, transmission, and fat-assed driver all in one place. Toss all-wheel drive into that equation and I get a race car that works, pretty much in any weather conditions. As a street car I get twitchy but controllable and decent gas mileage because everything’s covered in bodywork or a bellypan out of the wind. There are still some major compromises to finagle, like getting squeezed to the left by the engine and transmission or widening the body by 10″ so I can sit on the left side of the body with nothing intruding from the drivetrain. I am really divided about this, because on the one side I get comfort and space to spread out, and on the other side I get better gas mileage from reduced aero drag and slightly better handling, and a cozy cockpit that keeps me in place because there’s no room for me to move around 🙂

OK just from a performance standard cramming that engine and transmission into the passenger side of the body and cramming me into whatever space is left over will get both the best handling and the best gas mileage and is a lot less work to produce, so I’ll be seeing if there is enough room left for me after the engine is installed in the unmodified body as soon as I finally get said engine and transmission pulled from the donor vehicle, so basically … never. Even if I get the engine into the body I’m going to have to do a lot of work on the body to be able to service the engine for things like oil changes and tune ups. Because of the computer control tune ups are going to be few and far between and consist of removing the injectors and getting them cleaned or replaced and replacing the spark plugs every 60K miles or so. The most frequent service I’ll be doing is changing the oil and filter every 12 months or 12K miles whichever comes first. But I’ll still need to be able to do it without removing the engine first, so either the body comes off or I have to cut holes in the body where I can get to the oil filter and spark plugs on what is now the front of the engine that will be the right side of the engine as it will be mounted in the car.

And just now on my YTM app it pulled up one of my favorite “go get ’em” pieces, the Emerson Lake and Palmer version of Aaron Copeland’s “Fanfare for the Common Man”. That bass line, man it just makes me want figuratively to kick butt and take names. If you haven’t heard it, recently or ever, give it a listen on YouTube. The complete string to enter is “fanfare for common man emerson lake and palmer” don’t even need to use caps or punctuation. This is Montage Music, when I do the video of building the TGS2, this is the music I’m going to play while the pictures flash by.

And it’s about time to put this to bed so I can go there too.

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.

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.