OK I don’t know how much you have been paying attention to the Mini Sprint-T build, but the exhaust that came with the engine kit is going away for something more like what the real thing will have. What the 1:1 Sprint-T will have is what used to be known as a Tri-Y header or now as the 4-2-1. The main reason for that is what I’m going to be using the car for and how. The car will be used for SCCA Solo and Goodguys Autocross racing, plus transit between races and general around town grocery-getting (that’s why I’m including a trunk with a locking lid). The “how” is the car will be geared to hit 60 MPH in 1st gear so no shifting during a run in Goodguys and very little in SCCA Solo, just gas, brake, steer (or gasbrakesteergassteergasbrakesteer…). The reason for the Tri-Y over the cheaper and easier to find 4-into-1 is torque curve, specifically the curve below the peak torque. Tri-Y headers use an effect of resonance to get more torque below the peak without hurting power above peak torque. They are also not the best-looking thing to have on an exposed engine, but I can fix that during fabrication.
But to do that I have to make a set of scale headers to fit the car, and to do that I have to decide which cylinders to pair up for most equal flow. On the SBC there are 2 cylinders on each bank that are right after each other in the firing order and would interfere with each other if they were on the same branch of the second Y of the header. So the trick is to set them up with a second cylinder that is as far apart as possible in the firing order so there is no interference (actually there still is unless you have a flat crank or a straight 4 engine). That is easy to determine, just write the firing order vertically twice in a row so that you have a column of 16 numbers. Even numbers are right bank, so you put a tick mark on the right side of the column next to all the even numbers, ditto the left side on the odd numbers. You will easily see the adjacent cylinders because there will be two tick marks in a row on the same side of the column.
Now the almost-tricky part. Since there are 4 cylinders per bank you have to start with one of the adjacent cylinders, and pair it with the non-adjacent cylinders and count how far apart they are in the firing order, then do it again for the other cylinder, then do it again twice more for the other adjacent cylinder. You will find there are two pairs that are 5-3 or 3-5 and two other pairs that are 2-6 or 6-2 and that if you pick the 5-3 pair for one adjacent cylinder then the other adjacent cylinder is 3-5 with the remaining non-adjacent cylinder. You now have which cylinders to pair up when you build the headers.
The tricky part after that is making it look good where the primary tubes join the secondary tubes, and not like a bundle of unhappy snakes. What I’m going to do is put the secondaries side-by-side so that from the side it looks like a short-tube 4-into-1 header.
Now if I had a big budget I would build 3 sets of headers, one using 3-5 5-3 pairs, one using the 2-6 6-2 pairs to see if there is any difference, and a third 4-into-1 with super long primary tubes to see what running the longest primary tubes I have room for will do in comparison. And maybe I would also build a pair that had the adjacent cylinders on the same branch just to see if what everyone says is true about the adjacent cylinders interfering with each other and killing torque. Because if it didn’t make any difference I would run the tubes the way it packaged easiest. Or I could do the same thing with different slip-on collectors for the 3-5 and 6-2 headers and the 4-into-1 and build a separate set for putting the adjacent pairs on the same branch. That would be a lot of header swapping at the dyno, but it would be an interesting experiment.
Up first is a wreck in TX. Bicyclist killed in Crosby, family seeks assistance Nothing about the mode, but with no intersection mentioned nor salmon cycling it seems like hit-from-behind is a good candidate for the wreck. If you have the inclination I suggest going ahead with the goFundMe donation.
Our Daily Ted. Morning Links: LA River bike path closed through Memorial Day, and biking & walking are booming in the US
Still in CA. Operation Firefly shines a light on night-time bicycle safety I am a big fan of lights for riding at night so you can see wheere you’re riding. Also because drivers are generally blind as bats and will run over anything not lit up like Times Square on NYE. And sometimes even if it’s lit like Times Square on NYE.
How in Hades’ name do you run into 4 cyclists waiting at a red light unless you aren’t watching the road in front of you? Two dead, two injured in Northwest cyclist involved collision Oh, he was chemically impaired, that’s how.
So the kid got hit because he wasn’t wearing a helmet, or because the driver was going too fast to stop in a residential area or? 8-year-old boy killed while riding bike in Indian Land The wreck scene was two turns inside the residential area and should have been traffic-calmed with a low speed limit since there were childrren playing in and near the street.
Not that the vote would change things as the petition was disallowed for lacking valid signatures, but the outcome was unexpected. BURLINGTON VOTERS SAY ‘NO’ TO KEEPING FOUR LANES ON NORTH AVENUE, SCHOOL BUDGET PASSES Really, who in their right minds puts a technical infrastructure upgrade to a popular vote?
CT wreck LEO are blaming on a salmon cyclist. Police: Wrong-way cyclist seriously injured in crash OK the narrative sounds really dodgy on this one, he was riding against traffic and then crossed to the opposite side of the road to get hit from behind? Does this sound like the wildest SWSS report since the cyclist hit on the right with the left side of the car after “swerving” from the right shoulder in Texarkana?
Hit-and-run in NYC. Hit-And-Run Driver Knocks Elderly Man Off His Scooter In Brooklyn Not a bike, but there was a bike nearly hit by the driver during his escape. You can see it in the video. Also sending healing to the victim on the mobility scooter.
Some parts of NYC are being dragged into the 21st Century kicking and screaming. The Boulevard of Life, Phase 2: DOT’s Plan for Queens Blvd in Elmhurst And people are fighting this because parking will be lost?!? How many lives is a parking spot worth? How many broken bodies?
Hard to make change in car culture when you still devote massive amounts of space to storing cars. Guest opinion: To make paradise, stop putting up parking lots
Another blow against automobile-centric hegemony by the DIY DOT. ‘Agents of transformation’ help spread traffic cone activism in Portland
They are trying to change things in FL. 3-Mile Bike Ride With Mayor Haynie Seriously, 2 years ago I would have dismissed a story like this as an opium dream, now it’s reality.
The country of Bermuda is too poor to stop killing people. Making roads safer ‘cost prohibitive’
Rider down in Jolly Olde. Father-of-three killed in cycling crash ‘after hitting pothole that had not been repaired despite repeated warnings’ The first report of this pothole was filed in 2009, seven freaking years ago. How many broken bodies can be attributed to this hole? And now a life has been lost.
How is killing someone while driving drunk “careless” and not “dangerous”?!? Van driver jailed for seven years after cyclist killed in multi-vehicle crash How many vehicles did this doufus hit and how many hit the cyclist?
This was a hard video to watch. Not because of the content, but because by the time I pulled this link up my laptop was stopping and eventually crashed while trying to load the video. I heard a lot of bleeping profanity, but the video wouldn’t show. Cyclist crashes avoiding pedestrians who were crossing when they shouldn’t have been
You’re riding your bike wrong, say scientists. How to ride a bike the right way, using science
And it’s almost 0400 and I’m feeling like I was run over. And believe me I know what that feels like, at least 3 times. Time for bed. If I hadn’t been tagging this as I composed it there wouldn’t be any tags.
Billed @$0.02, Opus
Witch on a Bicycle 