I still haven’t made it to buy the butane and bolts. For some reason I just haven’t been able to get myself over there even though I have been able to get out of the house for other things. It’s even within walking distance, or what used to be walking distance until recently. What with the problem I have been having with my hip, and the problems I have been having not falling on my face when I get tired. So I don’t know what the problem is in getting butane and a few bolts. I plan on making a loop to the Lowe’s Wednesday after the Lab Rat Keeper to get the stuff, so no excuses.
I’m still tracking down why that one 383 build with the FIRST TPI manifold had such a steep drop-off of the torque curve. The data I have so far indicates the cam might be to blame because the guy that sells the manifold says the manifold does exactly what I saw in the video, but it can still make power at high RPM with even more displacement normally aspirated, and the heads were aftermarket aluminum so they should not be the source of the problem, either. That leaves only the cam in the Otto cycle (suck, squeeze, bang, blow) power equation unaccounted for. As I said in an earlier post the power output is fine, but the lack of power above 5000 RPM isn’t. So, more research on the cam specs is in order, and if it is a lift or a duration issue, or a combination of the two. Because head design does figure into it, how the intake port flows at low lift compared to high lift can dictate the cam specs. A combination that has relatively lower flow at low lift but greater flow at high lift (compared to another port design) requires spending less time at low lift and more time at high lift, so getting a cam with really high lift to get through the “bad” part of the flow as quickly as possible would be better than a longer duration cam with lift that wasn’t as high, Or given this manifold uses acoustic tuning for ram effect, maybe leaving the intake valve open longer would allow more ram effect and more air in the engine. Engines, like life in general, are a series of compromises.
I still don’t know what engine I will use on the Sprint-T, but I don’t seem to be able to let this problem go. I might end up with a Pentastar still, or a Subaru, or whatever I find that I can afford and get to the house. But right now I want to solve this mystery.
And I also need to get my fuzzy butt in a bed right now, so time to put the post to bed, unintentional pun.
And keeping me awake at night.
Remember that dyno test video I linked to last week? The one that had 490 Ft-lbs of torque but only 405 HP? I keep going back to the graph that could be seen near the end and wondering why the power graph just went flat above 5000 RPM. A flat power graph usually indicates maximum airflow has been reached and no matter how high you twist the engine T*RPM/5252 just isn’t going to get any better because torque is falling as fast or faster than RPM is rising. You just can’t burn any more fuel because you can’t get any more air in the engine. And what has been keeping me awake has been where is the restriction? The possible sources are the manifold, the heads, and the camshaft profile not allowing the other two to work above a certain RPM. If it’s the cam or the heads then that means just a different choice of parts during the expensive part of the build, but if it’s the manifold I might be able to crutch around the problem with gearing.
Because that torque number is freaking ridiculous. This is a normally aspirated build that had higher torque numbers than some supercharged or turbo builds, meaning the ram effect was taking the engine to >100% Volumetric Efficiency (VE) at torque peak. And looking at the torque graph in the video the peak torque was on the second torque peak, there was another peak at much lower RPM that was almost as high. For a NA engine that would be a torque number more natural for a much larger engine, the engine was taking in way more than its displacement without the use of mechanical assistance. Now all I need to do is figure out how to keep that up well past torque peak or I’m going to be stuck with a power band that is only about 1000 RPM wide, the space between peak torque and peak power. I’m still talking about installing a crazy cam profile, probably stupid high lift, to keep the airflow up well past the torque peak, and adjusting the gearing to put the power higher in the vehicle speed range, which would be fantastic for fuel economy. I mean the gears in the transmission are set in the factory, so the only thing I can change would be the final drive ratio to a higher (lower numerical) ratio. And because I don’t have room for a clutch pedal with a SBC that means if I set the final drive to hit redline in first at 40-60 MPH the cruise RPM would be ~4.6:1 lower than that. Which would mean very low cruise RPM and pretty good fuel economy.
Now I need to get ready for game.
I was reading some of the online newspapers like Gothamist and BikePortland, and the same old anger that made me quit writing about wrecks a few years back came bubbling up, mostly about people in cars making life dangerous for cyclists just to save a few seconds or a few steps. Gothamist was talking about towing cars from bus lanes (but not from bike lanes), and BikePortland was talking about right hooks in general and an injury wreck that appeared to be a right hook in specifics. Basically it was all about cars in bicycle infrastructure and not getting penalized for it. I don’t want to go down that road again, because the eventual destination is not good for me, but I do want to make a statement: If you see a car parked in a bike lane you should put down road flares to direct bike travel around the car and car travel around the car, and the tow truck, and bikes that will have to move into the general travel lane to get around the car. And if the flares happen to get too close to the car and maybe cause a tire to blow up or the gas tank to catch fire, well that’s just one of those things that “happens”, you know? Kinda how cars hitting cyclists “just happens”. Because putting down flares to direct traffic around an illegally parked car is all for safety, not to “accidentally” give the entitled driver an extra-judicial “traffic ticket” and fine. And if a bunch of illegally-parked cars catch on fire or blow up the left rear tire, they shouldn’t have been parked illegally, right?
Because traffic enforcement should never have to be a DIY project.
I didn’t get out to buy butane and bolts today because Mrs. the Poet got a call to go to lunch with a friend and I had already started a pot of beans and couldn’t leave them unattended for the hours and hours they need to assume their beany goodness. So she went out and I stayed with the beans, and I will go shopping on Friday. NBD.
I’m sitting at my desk eating my last meal of the day, which is usually the sandwich and veggies Mrs. the Poet makes for lunch, but because she went out for lunch I had to scrounge up my own food today, after spending hours slaving over a CrockPot full of beans and ham bone. In such a situation my goto meal is usually something in the ramen family or cup noodles, this time microwave ramen bowl with veggies. It is just a constant source of amazement that that tiny packet of dehydrated veggies fills so much of the plastic bowl the noodles ship in. I mean the package is barely as big as two matchbooks, but after cooking there is about a third of the bowl full of veggies. The noodles hardly change at all, but when the veggies are rehydrated suddenly there is a bowl full of food in front of me. I don’t care what others say to me this is one of the miracles of the modern age.
So anyway while I was making sure nothing bad happened to the beans I had some time to think about the reason for the shopping trip. One thing I came up with was spending the extra money for a second 5/16” bolt to make the jig for the roll hoops, since they are going to be identical now. And with the jig I could theoretically make a kit for converting the AMT T roadster kits into a Mini Sprint-T if that seemed like it was a good idea. Right now it isn’t, but that might change in the future, who can say? Certainly not me. My prognostication abilities aren’t that precise. When I was asked to look at the possible outcomes of Bush v Gore I saw battles and chaos and interpreted that as possible civil war or riots in the streets, not the Iran /Afghan wars.
Anyway, back to the car model, if I can find some good wood in the garage I can drill a couple of holes in it to put the bolts into that would be the right distance apart. Then after making the first bend I could use the second bolt as a jig and make the second bend to make the hoop the exact right size for the frame, using guide marks on the jig to get the angles right, which is almost a pun, because both hoops need to have their legs bent to a right angle to the top bar of the hoop. The design has gone through some iterations where this was not a true statement, but for the time being it is true. Both hoops are the same, same width and same angles, and when the frame is finished and painted the internal bracing for the rear hoop gets bolted into the 1:1 Sprint-T after the painted and wired body gets slipped inside the frame and roll cage. Technically that should be a slash (/) instead of the word “and” because the frame rails go around the roll cage which forms structural bulkheads in the frame and the roll hoop bracing becomes part of the triangulation of the frame. As I pointed out years ago now, frame stiffness is a function of d4 where in this case d is the average distance from the bottom of the bottom rail to the top of the top rail, and running the top rail over the roll cage increases d to the max it can be without making either the top or bottom disconnected from the rest of the frame. And it’s much easier to build the frame with removable sections than it is to either spray the body inside the frame a different color, or build the frame around the body without causing damage to the body or getting overspray on the frame or body or both. The tricky part for the model is getting that same effect without messing up the paint when gluing the braces in the frame. I think I might need to use cyanoacrylate for these joints instead of my usual Testors solvent cement because “assembled after paint” so these joints will require a bit more patience fitting together than the ones for the solvent cement. And it’s starting to get to be time to hit the sheets, so I’m cutting this one short here.
I found a You Tube video that makes me seriously reconsider using the FIRST TPI efi manifold. One of the things I had been led to believe was this manifold had an extended RPM range and kept on making power at high RPM. Well, I guess compared to the original TPI from the ’80s and ’90s that would be true, but this test showed a power peak well below the calculation crossover at 5252 RPM (HP= Torque in Ft-lbs*RPM/5252, the point where Torque = HP is 5252 RPM) and the BluePrint crate 383 makes more power and continues to breathe through a Chinese dual plane manifold and 750 CFM carburetor. Now granted the FIRST manifold made 44 more Ft-Lbs of torque, the type of head used for the FIRST manifold test was not listed, and the cam was not mentioned, but the BluePrint engine made the same torque (440 Ft-Lbs) with both a flat-tappet and a roller cam and that Chinese dual plane manifold and Holley 750 CFM carburetor. Something else not mentioned was the headers used in the FIRST test, where the BluePrint tests with 13/4” long-tube headers. Now for an engine packing 383 cubes that is a low-end torque header. Note edited 2019/26/1 to correct header tube diameter from 15/8” to the current size after getting better information.
Well, I plan on making a trip to Lowe’s today to get a couple of 5/16” bolts for the roll cage bender, a 5/8” bolt for the exhaust turnout bender, and a can of butane to make the bender work. So I should probably get to bed now.
Mrs. the Poet said I should just put the checks for the taxes in the mail this week and not worry about it. We kinda played some for the Shadowrun game on Sunday, but mostly with the weather doing the yo-yo thing I have been doing my “bear in winter” impression. Seriously this weather is seriously sapping my desire to even get out of bed at whatever time I stop sleeping. I have been huddled under the covers being borderline depressed, as in episode depressed, and not managing to work up a care to even check what has been wrought against the country by People Enabled By Russians. I mean I saw the kid from the Catholic school bothering the Native American Elder after marching against women controlling their own bodies. Because that is a thing that Catholic School Boys do, protest women controlling their own bodies and bother Native elders.
Other than that I have to pretty much force myself to eat anything after breakfast because I’m just not hungry after I get morning coffee, even if “morning” is 1300-1600 or so, like I wrote earlier getting out from under the warm blankets is very hard because warm, and because there is a cold draft blowing under the desk where I do my computer stuff now. Out away from the desk is fine, but under the desk is freezing (well colder than the rest of the room) and I really don’t want to get out from under the blankets to go work on the computer, which I have to do because otherwise I can’t post to this blog. Seriously, I can’t type worth a damn on my phone so if there is going to be a blog post I have to stick my legs under this drafty desk. I keep a blanket to cover my legs when I’m using the computer because otherwise I’m overdressed for the temperature if I’m warm enough under the desk. And with the current weather it’s even worse than normal because the wind forces the cold air through the leaks in the window.
Anyway, to kill time I have been looking some more at the FIRST TPI intake and fuel injection manifold, and it seems to be an intermediate step for the SBC between the LS engines and a carburetted engine, with low RPM torque like a dual plane intake and small 4BBL and high RPM like a single plane intake with a huge Dominator-style 4BBL. Or in other words very much like an LS engine with the plastic manifold but still only coughing up SBC change instead of LS engine co$t$. I think I mentioned this build is more about powerband than peak HP, because there is at least one turn that will see near idle speed in first gear on the majority of Goodguys courses and almost no place to use a high peak power. That is exactly what this manifold is made for.
And making another right-angle turn at full speed in the narrative, the stainless steel raw stock for the Mini Sprint-T suspension came in today in another ridiculously overpackaged container. The shipping container was worth more than the raw stock inside it. Anyway what came today was 1mm OD stainless tubing that will fit the simulated heim joints perfectly from Dirt Modeler and is something else that requires the use of the butane torch I bought at Harbor Freight to join together with intended parts. I still have the pure solder (no flux) left over from making the hot water heater for the camp shower a few years back, there was a minimum required quantity that was about 3 times as much as I needed to make the heater, so I have enough for several thousand simulated heim joints that require only a tiny drop of molten solder to affix them permanently.
Life has been very uninteresting lately, it’s winter and that uncomfortable kind of cold that can’t be dressed properly for. I’m either still cold, or sweating because I have too much on, or both because the temperature can’t figure out what it wants to do. I still have to pay my property taxes now that I found out that at least one of the offices does not accept debit cards and I managed to track down my checkbook that I hardly ever use except to void a check when someone prefers to pay by direct deposit.
So I have my checks for whenever the weather improves to the point I can do the walk between the three offices on State St. in Garland. In good weather it’s a nice walk from 5th to Garland Ave, less than a mile. And there are bus stops on both ends but it is only a short walk from Downtown Garland station to the first tax office, less than a quarter of a mile.
And at some point I really need to stop at a CVS or other store that carries butane to fuel the torch that heats the bender for the plastic rod I’m using for the frame of the Mini Sprint-T. And while I’m on the subject of cars I found a really good intake manifold for a SBC to use should I wind up running a SBC on the 1:1 Sprint-T. This manifold is an evolution of the TPI GM intake from the late ’80s early ’90s, that produced prodigious low-end torque but ran out of breath above 3000 RPM partially because of the state of the art for EFI at the time. Well this version breathes all the way up top, with “top” depending on displacement but generally higher than a factory cast crank will live with. The tech person I was in chat with says for a 383 the “top” is above 6000. The tech manual advises against using E85 but the only thing I can find that might not be compatible with the fuel is possibly the fuel injectors or the rubber injection lines supplied. Those are all easy to replace with alcohol rated devices or materials. The crank and piston kit I’m looking at has a max continuous of 5200 RPM or a short-burst redline of 5500 RPM.
Finding a kit to build a 383 that runs on 87 octane NA is another problem entirely. Most of them are too high a compression ratio for 87, or built for forced induction and cost too much because they are designed for higher HP than a NA engine can make on either 87 octane or E85. Sure that makes for an engine that is unlikely to fail even during racing, but I could buy a kit not made for boost that would be just as reliable and a bunch less expensive if they would use the same parts they use for 93 octane except for the extremely dished pistons in the hyper eutectic material instead of forged used in the boost-capable kits. Locally the difference between 87 and 93 octane is $0.30-0.50/gallon, or about 20-30%, and E85 is about a penny more than 87. Depending on tune it might be cheaper to run on E85 all the time using the 93 octane kit if I wasn’t concerned with availability for long trips. But for that I have the possibility of running a storage tank in the tire trailer to extend the range enough to get between E85 stations on the Interstate when driving between races, and there are plenty of places to refuel locally.
I know, pics or it didn’t happen, but I forgot to take pictures. I still haven’t gotten any butane for the bender, but I’m working on making diagonals to fit smoothly to look like both crossing diagonals are one continuous piece. It’s tricky, and kind of a cut and try thing to get both halves to match up. Many mistakes were made and discarded.
I have been so busy with this I forgot to take pictures, forgot to watch the Formula E race I recorded, and would have forgotten to eat if Mrs. the Poet hadn’t made dinner and yelled at me to come eat after I checked to see if the meat was done enough. I have been seriously spaced about this.
And now I need to check e-mails and get caught up on the day.