Tachometers are great. The information they provide can be used to save gas, avoid detonation, or just get an all around better feel for the performance characteristics of your vehicle's engine. But what if you could have something a bit more flashy; a bit more visually stimulating than that plain calibrated gauge?
This is pretty self explanatory but I'm going to explain it anyway. Let's say you have an eight cylinder engine (as well you should). You have a small panel with eight LEDs arranged in two rows of four longitudinally (or laterally depending on the arrangement of the engine). Every time your number 1 cylinder fires, your number one LED lights up. As do cylinders and LEDs 2 - 8, respectively. This will provide you with the same information as the tachometer minus a wee bit of data accuracy, BUT this would also alert you to any cylinder misfire/ sub nominal output if the LED bank used input from Pressure Sensor Sparkplugs (United States Patent 6359377), or cylinder heads with pressure sensors built-in.-- MikeD, Sep 29 2008 Hmmm, The firing order for most SBC V8s is 1-8-4-3-6-5-7-2. I dont think you would see a wave like you would on an inline 4 cyl. Either which way though, I think it would be esthetically appealing.
p.s. Curse you anonymous fishboner-- MikeD, Sep 29 2008 (+) This would bug me driving at night if it had no dimmer switch.-- 2 fries shy of a happy meal, Sep 29 2008 Why not drill the bonnet (hood) over the engine in a 2 x 8 pattern and put big multielement weatherproof LEDs in ?-- 8th of 7, Sep 29 2008 What does "2Hz per cylinder" mean?
At 1000RPM I think you'd go through the whole sequence at 8Hz.-- Srimech, Sep 29 2008 Use neon lamps. They run on the spark.-- Amos Kito, Sep 29 2008 "At 1000RPM I think you'd go through the whole sequence at 8Hz." I concur. I don't think you'd get much out of it, they'd be flashing too fast to be of much use.
How about one of those fall-away bar graphs? Or something like a CHT gauge?-- phoenix, Sep 29 2008 Fiber optics. Put the end of a fiber in each cylinder and terminate the other end where you can see it.
You can diagnose firing, misfiring, fuel ratio et cetera provided your eye is fast enough.
I think Jules Verne had a recipe for such a potion in one of his novels.-- neelandan, Sep 29 2008 What's the frequency Kenneth?-- 4whom, Sep 29 2008 Seems a bit fast to read and you need the extra sensors to get real data. To make the numbers clean, any cylinder of a four stroke engine at 1200 rpm will fire at least 10 times a second. Many fire on both strokes so the coils can be banked. So even if you have a good eye, you are not going to spot an intermittent misfire. The situation gets worse at higher revs. If you are sensing it by checking current in the wires, you'll miss carbon shorting on the plugs and several other reasons caused by bad spark. Running fiber is very cool, but not cheap.-- MisterQED, Sep 29 2008 At 1200 rpms (20 revs per second) one out of eight cylinders would fire 2.5 times per second. I think for regular driving (2000 - 3000rpm) this would not be too fast to notice. I could count rounds sent down range on a machine gun that fired 900 rnds a minute. And if a cylinder was misfiring, I think you would notice it even if it was intermittent, and definitely if it was misfiring every cycle because the bugger wouldn't be lighting up at all. And to answer your question [miasere] evens on one side odds on the other (any V-n config) one and two being towards the front. Did you all miss that this thing runs off of pressure sensors? If the pressure in the cylinder doesn't reach a certain amount (I believe 100psi * compression ratio) then the LED wont light.-- MikeD, Sep 29 2008 I don't follow you. At 20 revs per second, each cylinder will fire 10 times per second.
[miasere] A 2-stroke fires twice as often as a 4-stroke. Someone is using some very odd maths here.-- Srimech, Sep 30 2008 // 2Hz... for a 2 stroke //
No it isn't! At 16rps, each cylinder in a four-stroke fires at 8Hz, and each cylinder in a two-stroke fires at 16Hz. It doesn't matter how many cylinders there are.-- Srimech, Sep 30 2008 If you used one of those dual-color red-green LED's, and light it red when you get to a pressure corresponding to compression, then light the green when the ignition peak comes around, you'd get yellow for good ignition, red flashes for misfires, steady red for a non-firing cylinder, and black for no compression.-- lurch, Sep 30 2008 I only autobone every idea I see of 8th of 7.
I'd like to know who the real boner is.-- Giblet, Oct 02 2008 random, halfbakery