Tag Archives: Sprint-T

Nothing to write about still

Nothing of interest has been going on the last few days except paying the phone bill and buying a lottery ticket. I have decided to start getting the materials for the frame because except for a few brackets the design doesn’t change with any of the engines I’m looking at. The reason I’m doing this is Mrs. the Poet has declared my Christma$ present this year is an engine hoist which won’t be much use aside from building a hot rod or frying a turkey. And I’m not kidding about deep frying a turkey . Well, at least I’ll have something I can use it for after I build the Sprint-T.

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I have more data

I finally found out the weight of a couple of different Subaru transmissions for comparisons with other engines and their intended transmissions. Especially for the Subie, using a transmission designed to bolt to the engine saves a ton of work.

Anywho, what I found out was the 2002 5 speed weighed in about 135-140 pounds, the later model 6 speed was 155-160, and the automatics were about 200-210. Also removing the front drive differential and drive shaft and welding the center diff solid took about 35 pounds off when converting AWD to RWD. So for the normally aspirated 2 liter engine bolted to the 5 speed with the front diff removed we are looking at an all-up weight of about 300 pounds and about 200 HP, to 460 for the 2.5l turbo bolted to the late automatic with the front diff propelled by 300 HP. And those power numbers are factory ratings, tuning for higher octane can raise those numbers considerably especially for the turbocharged engines that can refuel with E85 and really crank the boost.

And thinking about this kept me awake most of the night and caused me to wake up way early, after only 4 hours of sleep. I need to go back to bed now. Except I need to clear my inbox before I sleep.

Flogging of the deceased equine continues

I’m running out of topics, but not running out of words. I was lying awake after going to bed last night and of course I’m thinking about the Sprint-T, as that seems to be the topic I can’t not think about. What I was thinking about was various engine and transmission combinations and relative performance advantages and disadvantages. Specifically, I was comparing the Pentastar V6 and the Subie turbo engines and their available transmissions.

Since I was trying to go to sleep I left my various calculation and information tools beyond arm’s reach so I wouldn’t spend the night punching buttons or tapping screens instead of shutting down and sleeping. That… didn’t work so well. Since I didn’t have a calculator handy I did everything in my head, which is the opposite of what I needed to do to get to sleep. When I’m trying to stay awake I do math in my head, a trick I learned from making cross-country trips as a solo driver back when I owned a business in Nashville but lived in Dallas. Anywho I didn’t reach any new conclusions, or even any conclusions at all. What I did reach was I need more information to reach a definitive conclusion. The question is will the reduced weight and higher potential peak power of the turbo Subie result in better autocross performance than the fatter low-end torque and perfect gearing of the Pentastar and ZF 8 speed transmission? Between the variable valve timing and increased displacement of the 3.6 liter Pentastar there is about twice as much torque on tap below 3000 RPM compared to the Subie 2 liter engine, but the Subie and transmission weighs about half the Pentastar and ZF combination, so it comes close to a wash and really depends on the course, with longer straights and more sweeping turns favoring the higher peak power and light weight of the Subie where lots of single pylon turns favor the Pentastar and its higher low-end torque and better transmission matching.

So I guess the answer is the best is whatever I get first. 🤑 So whatever is available when I have the money, that will be the best choice. And the post title is “beating a dead horse” with more expensive words.

I found another problem

I was doing a little SWAG on the Sprint-T and tires and I came up against another problem. I can only hook up so much HP no matter how big I get the tires, because of weight. Traction is a function of weight and tires, and there is a hard limit to traction with a car as light as the Sprint-T trying to use UTQG 200 treadwear tires. I can get a little more power to the ground with sticky race rubber, but depending on the weight of the car I’m looking at 300 to 500 HP without boiling the tread off the tire before getting the pedal to the metal. More than that and I’m never getting my foot to the floor.

What I’m looking at is with the Subie engine and the T5 transmission I can stop cranking up the boost around 300 WHP, with the Pentastar V6 and the 8 speed transmission I can stop trying for more than 375-400 WHP because that transmission just weighs that much, the LS3 and the 4l70 I can pretty much leave in stock tune, and the LS7 I will need to put a block of wood under the gas pedal to keep rear tires on the car unless I’m running the softer compound of the race slicks I have available. Street tires will require really feathering the gas to maintain traction with just the stock 505 HP tune.

Now these are just what they used to call “back of the envelope” calculations but they are the best I can do with the data I can get, and the low precision of the data. Seriously I’m looking at ±0.1 G precision on a 0.8G predicted grip for the 200 wear tires, or 0.7 to 0.9G and a huge difference in performance between those numbers, so lets say we are talking about the LS7/3 we are looking at maybe 400-430 WHP on the low end, just shy of 500 at the high end. And as far off as I was on the unsprung weight at the front end I’m not putting much faith on these numbers either. But if the data is correct and I used to correct formulas, If I’m running an LS7 then I don’t need to use the dyno for anything more than fine tuning for gas mileage and verifying the stock tune is working correctly. Pretty much the same for the LS3 except I have more room on the other side of the equation, I could get away with maybe the 480 HP tune, but not the 525 HP tune.

And I didn’t get much sleep last night, and I’m starting to get a headache, so bedtime.

Not making much progress

I have been thinking and researching and thinking some more, but I still don’t have much in the way of progress to report. Also the injured finger has been breaking open and bleeding all over things, which can get a little messy as well as not safe because of spreading a growth medium for germs, so I took a walk to the CVS and bought a fresh box of bandages using the last bit of money left in the gift card this one gig I work uses to pay me. But seriously, I really had to buy a box of bandaids yesterday. When I take the old bandaid off the clean the finger I’m constantly snagging the flap of skin still attached to the finger and pulling it up and causing the injury to bleed like mad, but the flap is still alive so I need to keep it attached to the finger so it will heal. The situation is unless I can keep that flap alive I will have yet another nasty scar on my finger…

The issues with the finger also affect the Mini Sprint-T. My dexterity is reduced and my grip is hindered and that means making the kind of precision cuts needed to build the frame is a no-go until the finger is healed enough to work without the bandage. A slip of 0.01″ translates to a part that is a scale 0.25″ too big or too small, and wasted raw stock if I make it too small. So I have to wait until I can handle my tools safely before I can get to work on the Mini Sprint-T. If there is one thing I have learned in my 60 years, it’s patience. I will have to wait.

Another thing I have had to worry about is the weight of the front axle assembly with all the bits and pieces attached compared to the sprung weight of that end. There is nothing I can do about the excess weight except turn the heavy bits into “drillium”, also known as “swiss cheesing” the parts. The process involves a drill press, a lot of time, and usually several worn-out drill bits as holes are drilled in areas that don’t get a lot of stress in use and shouldn’t suffer fatigue failure. This only goes so far, and the parts that have the highest weight can’t be drilled out, like the spindles and wheels and especially the tires. Drilled tires would be useless. 🙂

And my finger is starting to hurt from typing, so this is pretty much it for the day.

Clear the deck I’m thinking again

That’s old sailor talk for “Take Cover!” I’m thinking about another potential powerplant for the Sprint-T that might actually fit and leave room for a clutch pedal, and not cost a pair of limbs in the process. There is a 300+ HP I4 DOHC turbo engine from Ford that gets pretty good gas mileage, is pretty narrow near the bellhousing, but is tuned for 93 octane and setting it up for a diet of 87 or E85 depending on if it’s freeway or race might be a little tricky. Just a bit tricky! And it’s about 20% heavier than the Subie. But on the positive side it’s the base engine for the last few years of Mustang production, I.E. the “chick car” version, and it also comes as a crate engine. The fact that it comes in the base Mustang means I might be able to snag one backed by an automatic transmission in case there isn’t enough space to install a clutch pedal with the right side against the inside of the body.

And for some reason that jogged my memory about the Pentastar V6 from FCA that comes in everything from minivans to muscle cars and trucks, and has similar weight and peak power to the Ford EcoBoost 4 cylinder, and also has a better torque curve for autocross, but FCA haven’t seen fit to sell it as a crate engine, and Mrs. the Poet has put a hard veto on donor vehicles unless I move the build to another location. If I get the Pentastar it will have to be from a junkyard and cleaned up before bringing it home. Well if I get any used engine and transmission, I’ll have to get it cleaned up before I can bring it home. Manufacturer doesn’t matter, not bringing dirty parts home is what matters.

And my head hurts again, so I need to get to bed now.

Sleep cycle is borked

And if you think daytime TV is bad try finding something good at 0200. I tried looking for stuff for the Mini Sprint-T as currently planned but the only Subie engines I found were in $25-$200 kits so I have a request going in the Facebook Scale Model Club for someone with a built WRX or similar turbo Subie they don’t want anymore, that I can rob the engine from. I just did that right before I started doing this post, so not enough time for a response yet.

One thing I did find that is still entertaining at 0200 or later is YouTube. I went back and caught some episodes I missed from my subscribed channels before they got big, surfed some recommended videos, and generally just wasted time between sleeps when I wasn’t trying to come up with a blog post or clear out my emails. Twitter was the usual sewer, for the most part. If it wasn’t for the fact I find stuff out on Twitter several hours before the news comes on I would just delete it from my phone.

So, anyways, I found out that one of the people in my RPG group has a new job doing something he actually spent tine getting a degree to do, which is going to make it pretty much impossible for him to do any game sessions during the week, which means because I’m going to be glued to the tube (actually the flat screen) all this weekend watching the three NASCAR touring series race their final races of the season and determine their champions we are not getting to play this week again after so many weeks of other people having scheduling issues. My fault this time.

And I really don’t have anything to say today except, Next Time!

It’s fun (not fun) typing today

The RPG group had lunch before game today and I helped with preparations by slicing vegetables with a mandolin. I also sliced my finger, thumb, and a fingernail, removing chunks from each one. And seasoning the veggies with a little blood. Just a note, there is not enough salt in blood to season veggies. And also the bandaid on the fingertip makes it really difficult to type because it catches multiple keys in one keypress and I might have to go back and delete one, two, or sometimes three wrong letters to fix a word. Yep, I can hit 4 keys at once with this bandaid trying to hold my finger together. I’m really hoping we got the sliced bit back in the right place, because I know if I did the scar will be small and almost unnoticeable, and heal quickly, or a huge purple-red dot on the end of my finger if I didn’t get it in the right place. The last time I sliced the end off a finger it got lost in the pepperoni and it took about 8 years to grow back to the point that it didn’t constantly remind me that I cut off the end of my finger in a meat slicer, and about 25 years later you have to know where to look to find it. And someone got a surprise in their pizza.

And I’m back to the place I was a few years ago on the Sprint-T, needing a front engine RWD vehicle as a donor vehicle for the drivetrain. Or spending a ton on a crate engine and transmission. And I really don’t want to drop money I don’t have to on crate parts. Seriously the purchased parts will not work for anything other than a front-engine RWD car without lots of ballast (added weight). And without doing serious damage to the polar moment to the point that it might as well be front-engine. Seriously, the only way to save the TGS2 would be to stick the front axle assembly into a corner or closet and just pretend very hard it never existed, while I build a featherweight front suspension to keep the sprung/unsprung ratio close to something sane.

Also since I can’t make any progress on either full-scale car, I’m returning to the Mini Sprint-T. After getting almost all the parts needed to start the build, I got the idea that building the TGS2 was possible, and I stopped working on the Mini version. I think that was a mistake now, but back then it looked like the right thing to do to stop making a model and focus on the full-scale car. At least now I can take pictures instead of writing thousand-word descriptions of what I’m trying to do.

And last thing before I run this through the proofreader, Mrs. the Poet came in complaining about walking like a penguin and asking if there was a song about it and telling me I should use my music app to find out. Well, it turns out that there are not one, not two, but at least three different songs with the title “Walk Like a Penguin”, one kids song that I won’t inflict upon you, a remake of the Bangles song “Walk Like an Egyptian”, and a rap techno song that I likewise will not inflict on you.

And I got up after 3 hours of sleep to go play Shadowrun, so I’m starting to fade out here.

I’m suffering from water damage

I sustained water damage yesterday, but not from malicious actions. It was raining yesterday and I had to pay my mobile bill or my phone would be shut down, and there were ankle-deep streams over the sidewalks in places because drainage was directed that way, on purpose, because it was cheaper than installing a culvert to direct runoff under the sidewalk. This resulted in soaked shoes that are still drying out this afternoon. It was basically just drizzling so my hat was a little damper than desired and the rest of my clothes were only slightly damp. But my shoes are still wet, after I dumped the water out yesterday.

Because the Sprint-T design is almost frozen because of drivetrain choices and previous purchases, my mind wandered back to the TGS2 with a FWD drivetrain installed as a mid-engine, because I might get a free one. (Hey it still could happen). Basically I didn’t complete the front part of the frame for the center-seat design of the TGS2, and I didn’t like what I had very much in light of what I had for the Sprint-T. After considering pull rods and rocker arms I decided direct-acting coilovers mounted next to the kingpin would be lighter, and most importantly, less expensive. And I can make it more rigid that way than I can with pull rods and rocker arms, plus as the saying goes parts not on the car won’t break or leave you stranded. Or get out of adjustment and cause bad performance. So, no suspension rocker arms. The design for the TGS2 has the frame rails running through the top and bottom of the firewall area of the fiberglass body with the front axle 13″ in front of the firewall, which will look a little strange, especially with the frame members running from the top and bottom rails to the top spring mounts, but that is the closest it can get without hitting the body at full steering lock. Any further back will hit the original bucket and look really strange. I mean really, really strange, like cab-forward taken to the nth degree. Also the 13″ distance allows for placing the battery between the firewall and the front axle, next to the steering box. This helps the front-to-rear balance but is terrible for the polar moment. But the polar moment was pretty good (I don’t have the actual numbers because I don’t have a theoretical engine and transmission, but the minivan engine and transmission had pretty low numbers when I ran them back when I thought I was going to get them any day), so moving the battery from the top of the transmission to just behind the front axle doesn’t make that big a difference.

Another good thing about the TGS2 is automatic transmissions are easy to hook up as mid-engine installations. Just run a cable from whatever I use for a shifter and connect it to the shift arm on the transmission, routing to miss exhaust pipes and other obstructions. And by whatever I use for a shifter I mean I could literally use any lever I want to move the driver end of the cable as long as the housing is marked with the lever location for each gear and there is some kind of detent to keep it from moving out of gear if accidentally bumped. And the brake pedal assembly is much simpler than the clutch and brake pedal assembly. Steering is simpler because there is much less junk in front to route around. The main drawback is Goodguys might not let me compete and only do “demonstration” runs. 😦

We have such small dreams

Mrs. the Poet and I were discussing what it would feel like to be rich while talking about the take home from the Lotto Texas drawing tonight. And as we did it dawned on me just how small we dreamed. And how little it would take for us to feel “rich”.

The big thing we kept coming back to was inspired by end-of-the-month grocery shopping, and having to eliminate items from the cart as we got closer to the budget limit, exchanging branded items for store-brand items, and just not buying stuff we could survive without. And a big part of our definition for “rich” became “don’t have to take stuff out of the grocery cart because we can’t afford it”, and the corollary “buy what you really want”.

Later we expanded on that to “have all the bills paid at the end of the month and still have money left over” and “get everything fixed and not have anything in the house that wasn’t fully functional”. Basically get back to where we were when I was working 7 days a week at TI back in the 90s, bringing home 20 hours of extra pay a week. We made a total of $57K that year or $100K in today’s dollars. We had a nice townhouse, savings, and I was taking flying lessons once a week. I had a “hot hatch” for autocross, my 87 Hyundai, and was building a Pt. 103 legal ultralight, so I was living my dream life at the time. So that’s what we are looking for with the lottery, living like I was working 60 hours a week at a good paying job, minus the working 60 hours a week.

And since I can’t stop thinking about the Sprint-T after considering the dynamics of the right side torque arm 22″ off center I changed my mind again and moved the torque arm over to the center section of the rear axle. Seriously the right side torque arm has the potential to steer the car left under power. And turning the swing arm into a two-piece radius rod would bind the axle as the car rolled into and out of corners. Not severely, but a bind at any rate. So the swing arms are back to free movement on both sides, and a new low profile torque arm is added to the right side of the center section.

Also the frame design was changed to the side rails extended to the far end of the car and a X braced crossmember placed vertically across the end to support the gas tanks and battery and the tonneau cover for the pickup bed. The bed is going to be similar to the original bed in that it won’t be attached to the bucket, but much deeper than the original Model T pickup bed, with the tonneau more or less level with the back of the body and the floor at the same level as the bottom of the bucket more or less, and the vertical crossmember will be supported by two diagonals running down from the top of the rear roll hoop, one to the bottom and the other to the top. There will also be two bolt-in braces at the rear of the frame to allow mechanical access to bits in the back and also allow the body to be bolted to the frame after the frame is completed. One brace will triangulate the rear hoop to prevent deflections during a rollover wreck and also provide a place to mount the shoulder harnesses, the other will be a brace across the top pair of diagonals from the rear hoop to the rear crossmember to stiffen the frame in torsion.

And yes I’m obsessive about frame rigidity especially in torsion. Torsional rigidity is essential in tuning for handling balance with springs and anti-roll bars, with a frame that is not torsionally rigid the only way to tune front-to-rear balance is by adjusting the roll center heights. While this works for fine adjustments it takes way too much movement of the roll centers to have that as the only way to adjust balance. That’s why the design for the Sprint-T has an adjustable mount for the Watt’s link, so that the rear roll center can be precisely tuned to balance the handling front to rear. The TGS2 has adjustable anti-roll bars to the same end for quickly adjusting the balance of the car for street or autocross or Solo racing, street driving requires a touch of understeer, but not too much while autocross requires a fair amount of oversteer, with Solo in the middle but biased more to the oversteer side because it’s basically the same as autocross, but faster. Goodguys course rules require top speeds “around” 30 MPH, where Solo rules allow speeds up to about 70 MPH. The descriptive term is “highway speed” for Solo, which was 55 MPH when the rule was first written and now could mean as fast as 80 MPH. Either way, Solo racing can get much faster than a Goodguys’ autocross or it can be about the same, so requires more tuning flexibility. But toss street driving into the mix, and you really need a simple and quick way to adjust the balance of the car from front to rear and back again.

And I mention the TGS2 because I haven’t given up on the mid-engine bucket if someone gives me a FWD car to use as a donor vehicle for an engine and transmission. I’m open to free 😈 I mean seriously open to free, as long as it is done legally, like asking to haul off a car from your land, or something like that. And seriously if you have a vehicle you need hauled off leave a comment 🙂 I will find a way. And if it’s a FWD minivan with an automatic transmission, well I’ll just suffer the ignominy of driving a slush box. Seriously, as light as the TGS2 is going to be it won’t take much to make it a rocket for SCCA Solo, even if the mid-engine makes it ineligible for Goodguys. And there is a chance I could still run Goodguys with a minivan engine and transmission stuck in the back of the car.