Super Bill is at it again
- Thread starter Stakebed
- Start date
Thanks for posting that Joe!
My pleasure.
I could not hear any dialog.
Share with us the inside scoop.
What did you learn?
What did you gain/lose?
How is the Kuran Eng head performing?
There's no dialog with the video. At 3000 rpm, I backed away from the engine compartment.
The goal of the tuning session was to improve starting and idling. It takes about 3 to 5 seconds to start and during that time I always get a cranking error message. Not sure what is causing the cranking error. As soon as the starter is engaged, the ECU starts syncing the cam and crank positions. When the error occurs (usually in the first 1 or 2 seconds) the ECU restarts the syncing process.
I'd like to decrease the start time to 1 to 3 seconds. At the 150 rpm cranking speed, the engine rotates just 2.5 times per second. I'm impressed with how quickly it starts but new cars prettty much start instantly. I'm working with a new tuner who doesn't think almost instantly is impossible.
The engine idles at 750 rpm but likes to foul the plugs, especially number 4 and 6. At the end of the day we (he) concluded that a leaking injector may be the problem. I removed them for cleaning. Hoping to get them back on Friday. The stock engine idles at 550 rpm. This tuner seems to think there is no reason the modified engine can't also idle at 550 rpm. I hope so because, at that rpm, cam lope will be very noticable which is a great attention getter at coffer and car meet ups.
I always learn something . . .
- I learned how to set up the tune using volumetric efficiency rather than speed density. The noticiable difference is how the fuel map is displayed. Speed density uses pounds of fuel per hour - volumetric efficiency use, well, volumetric efficiency. You're right, I don't actually understand the differnce!
- I discovered that I don't fully understands the magic of water-methanol injection.
- I discovered a way to remove the fuel injectors without draining the coolant. The rear end of the fuel rail is directly under the heater hose that goes between the cylinder head and the heater control valve. This was a real victory! You can read about here.
- Boost (pressure ratio) is a nice number to throw around it is not the right thing to look at. The density ratio tells you exactly how much more air (numbe of molecules) you have to work with because it accounts for air temperature and humidity. I may have 10 lbs boost (1.68:1 PR) but if the air is humid and hot the DR could actually be less than 1:1, Density ratio is a good way to measure intake air efficiency. Fresh air intake rather than under the hood, using an intercoooler, W-M injection are ways to increase efficiency.
Bill, you may have posted this somewhere but, I don't remember much. What is your squish dimension with the new head and how thick is the head gasket? I know 0.035" is optimum squish. I reduced this dimension from 0.105" to 0.055" on my old motorcycle flathead. Much improved starting and more bottom end for sure. So, can you share what you came up with for the new cylinder head? I hope you can. Getting mine closer to optimum REALLY made a difference.
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Larry, squish is 0.041 inch. The copper head gasket is 8 mm (0.031") but there's 0.010" deck clearance. The 8.7 CR Edmunds head, with the 0.062 thick OEM gasket, had a 0.073" squish height which doesn't generate effective turbulence. It's difficult to say if it's better because the CR has also changed. For sure, not worse.
Doesn't being a flathead and having a big combustion chamber that is not centered over the bore really mess up the ability of tight squish to provide many benefits?
Joe - I think a flathead benefits from squish because of its long chamber. It can have squish area (or quench area) equal to the piston area but 50% of piston area is more common. My OEM chambers had just under 50% of piston area as squish area. The new head is just over fifty percent. On my engine, squish and quench areas are the same, but they do different things.
Quench helps prevent detonation by not supporting combustion in that area. Quench height has to be 0.030" to 0.050" to be effective.
Squish supports combustion by creating turbulence in the combustion chamber. Squish area, squish height and piston speed determine squish velocity and the energy available to create turbulence.
Since the squish and quench heights are always the same, it takes some thought (luck) to come up with the most effective area (the shape of the area is also a factor).
It's my opinion that establishing effective squish and quench are two very important aspects of side-valve engine cylinder head design.
Quench helps prevent detonation by not supporting combustion in that area. Quench height has to be 0.030" to 0.050" to be effective.
Squish supports combustion by creating turbulence in the combustion chamber. Squish area, squish height and piston speed determine squish velocity and the energy available to create turbulence.
Since the squish and quench heights are always the same, it takes some thought (luck) to come up with the most effective area (the shape of the area is also a factor).
It's my opinion that establishing effective squish and quench are two very important aspects of side-valve engine cylinder head design.
Thank you Bill, In my experience getting the squish just right is of equal importance to the compression ratio. As you know actual cylinder pressure prior to ignition is what makes the power. The ratio is just one of many variables to make that pressure. And without proper turbulence, the mixture will not completely burn. If I had a Hurricane in my pickup, I would change whatever was needed to get that 0.040" to 0.035" squish dimension... Again, many thanks.
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All flatheads I've seen have about one third of the bore covered with a flat area on the head, next to the chamber. And there is a reason for that beyond making enough compression pressure to make power. Proper squish ensures complete combustion, better fuel economy, easier starting and on motorcycles...........Less exhaust pipe blueing............But, whatawino?