RodneyPierce
Well-Known Member
- Joined
- Mar 26, 2006
- Messages
- 4,464
thats why I run GO engines :lol: :lol: :lol:
thats why I run GO engines :lol: :lol: :lol:
thats why I run GO engines :lol: :lol: :lol:
So the intake systems that let the fuel puddle up will have a hard time on launch. this makes senses less velocity at low RPM fuel settles. It seams that the rotor timing will control the velocity at certain RPM. With a lot of duration the eng turns into a ram jet kinda. The pipe would have to match the system. Get it out with a wide angle and balance it with the same back angle......and Dick Jones got the BDC from me.There you have it! BDC/65. Makes for a great race engine! Got to be careful on crank induction engines though, because the crank will get weak and there is not much room to work the case seal area.
I took two peoples advice to come up with this setup. Marty for the 65 ATDC and Dick Jones for the BDC opening. Pays to keep a open mind and listen to every one.
David
Marty, The early opening helps the torque. It becomes huge and it's really noticeable in the Monos pulling through the corners
Got to be careful in the rigger though it can KILL the launch.....but once you get the prop hooked up the torque comes alive.
The biggest launch problems are with the standard type drums, Picco, old CMB and New VAC so be careful about cutting on those drums in a rigger. That is why you'd see me load the prop in the water before launching the rigger back when I ran Picco and CMB. BUT once you get all of that extra fuel burning, you got Horsepower baby!
Not a problem with the Ruasian/MAC style drum....or crank induction engines.
Lohring check this out. Let me know what you think?It seems to me that later closing timing when coupled with high exhaust timing improves the rpm and over rev. We ran 72 degrees ATDC closing on a CMB 35 to get the over rev we needed from a SAW engine. However, everything needs to match. The time-area of all the ports has to be enough for the target power. Programs for time-area are widely available. As far as I know they all originate from Gordon Blair and were available on a CD with his book. More detailed advice was once sold as TSR port 2000. A description of it can be found here:
http://www.macdizzy.com/19896hopup.htm
Lohring Miller
These types of intake housings are definitely directional for flow .Andy,Stan Simpson built a Picco 45 bluehead with 30* BBDC/65*. That's a total of 275 degrees of duration. It ran 97 mph in the 45 SG in Oval trim and 107 mph in the same boat minus the turnfin. That was back in 1998.i have heard of great gains on the opening side of the rotor.. i cannot verify this but have talked to some people that say it is better to open the OPENING side.
but i have read in books that the closing side is where it is at.. so i will be waiting to hear on this.
chris
If I am understanding the intake housing of that Picco correctly the disc valve opening is in the draft of the big end of the rod? Probably the only style of intake that would allow an open timing that early?
Do you know if reversing the rotation of that engine resulted in less power, assuming the open/close timing are the same? The housing flow path looks like it favors the standard rotation.
Steve maybe that engine was run in a gear drive set up. I did that with my OPS and gear drives back in the 80's.A picture so you guys can see what I'm talking about. Housing to the right looks to me like it was run reverse rotation?
Steve,A picture so you guys can see what I'm talking about. Housing to the right looks to me like it was run reverse rotation?
Andy:Steve,A picture so you guys can see what I'm talking about. Housing to the right looks to me like it was run reverse rotation?
I have never used BDC opening timing on that type of disc. My first experiences where with early CMB GranPrix engines with Zimmerman valves, then on Picco and CMB drums when they came out.
Steve,
With an open time of 30 BBDC there it still 30 degrees of transfer opening (with transfer timing of 120) for the crankcase to evacuate before the intake valve opens. The correct pipes will help the case empty more quickly. Lab testing in reed valve engines show that the reed begins to open just before BDC in many situations.
Something that could not happen if a vacuum did not exist in the crankcase.
Marty,
Leaner? Not reliably. Low end needle? I don't know.
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