That will keep someone busy for a min.
Take a guess how much HP gain with illegal springs !!!
- Thread starter Mr angery
- Start date
That will keep someone busy for a min.
alvin l nunley
Site Supporter
what's interesting to me is that when I ran my dyno with my KT100, (no valves no springs) I got the same kind of bouncing as you have. I put it off to the chain bouncing. You could stand there and watch the chain bouncing up and down like crazy. I wrote smoothing software like you show. Not real precise but good enough.
If I was to do it again I would have something like a dampener for the chain. A single cylinders power curve is not flat. Just a guess.
Big Chris
Member
No chaindrive here AL, directly coupled to crankshaft.
Any chance you'd be up to the challenge?
Jamie Webb
New member
Run the test 10 more times and the blips and glitches will be in different places. It's the nature of a single cylinder engine and using electronics to gather information. That is why all dyno software includes "smoothing" settings. I set mine on light so I can see if there are spikes or drops in HP, but even Kevin at PT will tell you to ignore the sharp spikes of unfiltered data. Discussed this with him before.
Goinbroke2
New member
ok, time to throw a curve ball;
You're seeing bumps at 37/47/5400...how do you know it's not resonance related to the intake or exh?
Astglenn, you're into FI? Well, have you ever seen the difference of different plenum sizes and the effect on hp/tq? What about runner length/dia. Then there's header primary pipes, same issue. Perhaps...PERHAPS what we're seeing is various combinations getting in sync at these rpm. In other words, the intake harmonics resonate best at 3700(remember I'm not talking flow or even ram effect) and maybe the exh effect 4700, the cam comes on and everything sync's again at 5400.
With efi, when you add fuel at a particular rpm and load, you're still dealing with all cyl's together (batch or sequential) if you can tune (and some systems can) each cyl individually (with a o2 reader in each exh primary pipe) than you could ultimately tune each cyl to the exact amount of fuel it needs. With the crower stacks, you can raise and lower them to tune each cyl individually because especially on a BBC, there is a huge variance between cyl's. What are you tuning with the stacks? lots, including resonance which effects ram.
When you run multiple cyl you have a choice of running equal length headers or not. Everyone assumes (because of marketing) that equal length means better. This is false. When all pipes are equal, all cyl make their peak together and yes you will have a higher peak, but at a narrow specific rpm. This is awesome if you're running a loose converter and close gear ratio's. You hit the rpm and keep it within the 500 or 1000rpm so you're "always in it". This is routinely done in drag racing with class cars. A stocker will leave at 4500, jump to 6500 and only drop 500 rpm on shift. The car is exactly in it's band and is accelerating on the converter. However, picture an engine that isn't maxed out and must go from 2500 to 7000. In that case, having each cyl hit their tq peak at different rpm gives a lower over all but more consistent or stable tq number. The highs of 2 cyl's cover the lows of 2 other cyls at a particular rpm so the powerband is less "peaky".
How does this relate to a single cyl? Well, in a 8cyl, if you tune each cyl for exactly what it wants, it will be better than a generic X length of runner or Y diameter of tube. In the singles case, we are dealing with the same issues, so it should be easier to figure out. I'd like to see the same eng configuration run again to confirm repeatability, then add 3" to the intake track or header and see what it does to not only the hp/tq but if/where it moves the "bounce" to or if it clears it up. Adding 3" to the intake for example might make it sync with the header or cam or....Just random thoughts....
You're seeing bumps at 37/47/5400...how do you know it's not resonance related to the intake or exh?
Astglenn, you're into FI? Well, have you ever seen the difference of different plenum sizes and the effect on hp/tq? What about runner length/dia. Then there's header primary pipes, same issue. Perhaps...PERHAPS what we're seeing is various combinations getting in sync at these rpm. In other words, the intake harmonics resonate best at 3700(remember I'm not talking flow or even ram effect) and maybe the exh effect 4700, the cam comes on and everything sync's again at 5400.
With efi, when you add fuel at a particular rpm and load, you're still dealing with all cyl's together (batch or sequential) if you can tune (and some systems can) each cyl individually (with a o2 reader in each exh primary pipe) than you could ultimately tune each cyl to the exact amount of fuel it needs. With the crower stacks, you can raise and lower them to tune each cyl individually because especially on a BBC, there is a huge variance between cyl's. What are you tuning with the stacks? lots, including resonance which effects ram.
When you run multiple cyl you have a choice of running equal length headers or not. Everyone assumes (because of marketing) that equal length means better. This is false. When all pipes are equal, all cyl make their peak together and yes you will have a higher peak, but at a narrow specific rpm. This is awesome if you're running a loose converter and close gear ratio's. You hit the rpm and keep it within the 500 or 1000rpm so you're "always in it". This is routinely done in drag racing with class cars. A stocker will leave at 4500, jump to 6500 and only drop 500 rpm on shift. The car is exactly in it's band and is accelerating on the converter. However, picture an engine that isn't maxed out and must go from 2500 to 7000. In that case, having each cyl hit their tq peak at different rpm gives a lower over all but more consistent or stable tq number. The highs of 2 cyl's cover the lows of 2 other cyls at a particular rpm so the powerband is less "peaky".
How does this relate to a single cyl? Well, in a 8cyl, if you tune each cyl for exactly what it wants, it will be better than a generic X length of runner or Y diameter of tube. In the singles case, we are dealing with the same issues, so it should be easier to figure out. I'd like to see the same eng configuration run again to confirm repeatability, then add 3" to the intake track or header and see what it does to not only the hp/tq but if/where it moves the "bounce" to or if it clears it up. Adding 3" to the intake for example might make it sync with the header or cam or....Just random thoughts....
Goinbroke2
New member
I was typing while others were and now I see the "it's the nature of a single cyl and electonic's"...there's always that too and after working with v8's, maybe I'm over thinking a little chinese motor! LOL!
alvin l nunley
Site Supporter
it just makes me wonder why anybody would want to be a 3rd rate comedian.
racer47
New member
Big Chris
Member
Thing is, it follows new vs used springs. No other changes. This is something I'll continue to work on.
Perhaps you guys are all right, it just glitchy data.
As for Al, he's reached critical mass. I know its hard to believe, but it may be beyond his limit. It's kind of like finding the end of the internet.
Perhaps you guys are all right, it just glitchy data.
As for Al, he's reached critical mass. I know its hard to believe, but it may be beyond his limit. It's kind of like finding the end of the internet.
JPMKarting
Site Supporter
Epic.
Jamie Webb
New member
Kevin at Perf Trends was telling me one time a guy had an inertia dyno with a very large wheel and used multiple magnets on the wheel and he could see exactly what you are talking about. With a single magnet or even dual magnet setup you will not see this though.
I think many of us talked about and had the theory years ago on the flatheads that the rods could actually be breaking on the exhaust stroke because of the "free spin" and increased piston speed and "yank" at TDC when it reversed direction.
paulkish
old fart
Very interesting.
Logically it then becomes more compression equals less output, because increasing compression slows an engines more on the compression cycle.
It also follows all 4cycle cycles hurt output, except for the power stroke. Instead of working to enhance intake, compression and exhaust, engine builders should be doing all possible to reduce actions of those three hp robbing cycles. Along with reducing efforts efforts, to cause power robbing compression.
I can see if you have only 2 strokes, compression may become more important to making power. Butt 2 stroke technology does not translate over to 4cycle technology, the same as "regular lefty righty racing", does not transfer over to LTO racing.
paulkish
old fart
From what Bob inputted, my follow up to his post, along with someone bringing up harmonics, led me to a question.
I see harmonics possibly being started between compression slowing an engine and power accelerating it. Assuming your flywheel is there to keep momentum in the engine between power and the slowing of compression, could you balance and reduce or cause harmonics to help, by adjusting rotating weight, to include flywheel and clutch?
... yep, proly a dumb question, but yep I think about a lot of dumb stuff trying to sort out some good stuff. ...
I see harmonics possibly being started between compression slowing an engine and power accelerating it. Assuming your flywheel is there to keep momentum in the engine between power and the slowing of compression, could you balance and reduce or cause harmonics to help, by adjusting rotating weight, to include flywheel and clutch?
... yep, proly a dumb question, but yep I think about a lot of dumb stuff trying to sort out some good stuff. ...
youngengines
Member
I think many of us talked about and had the theory years ago on the flatheads that the rods could actually be breaking on the exhaust stroke because of the "free spin" and increased piston speed and "yank" at TDC when it reversed direction.
^^ I agree... We have seen this in car engines.. Guys have nitrous on a cast piston engine.. and when they go a little too far, it jerks the pin out of the piston... That "snap" is hard.. especially on the exhaust stroke.. IMO
^^ I agree... We have seen this in car engines.. Guys have nitrous on a cast piston engine.. and when they go a little too far, it jerks the pin out of the piston... That "snap" is hard.. especially on the exhaust stroke.. IMO
Bob Evans
Administrator
Remember that we are dealing in averages, so not necessarily so.
Contribution to engine vibration might be a different deal altogether.I'm sure there's a point of diminishing returns.
I do believe that all aspects of single cylinder race engine need to be examined closely, and adapted to single cylinder performance potential to obtain the most
desirable result from the engine.
One must also consider the track conditions, in order to determine what rpm range will be the most productive to run in.
In order to fully accept the facts of the track condition, one must also measure the time spent in the so called "speed bins."
desirable result from the engine.
One must also consider the track conditions, in order to determine what rpm range will be the most productive to run in.
In order to fully accept the facts of the track condition, one must also measure the time spent in the so called "speed bins."
alvin l nunley
Site Supporter
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Compression is the Holy Grail up to the point of detonation.