vStrandell
03-04-2012, 11:57 AM
Hi, I'm new at this very nice forum so I don't really know if this is the right place to post this. And sorry for my bad english :)
http://www.boatracingfacts.com/forums/showthread.php?t=13813
So, I got one a boat called TG Special, made in finland by Tage Gustafsson back in the 70s, it's V-type boat that is 4 meters long, about 1,8 wide, weights about 43kg/94.8pounds (without engine and driver) and got quite big wings and a Mariner 9.9/15hp eninge made by yamaha in 1986. I got it in the middle of the last summer and some tuning was already done on it.
The carb is a 20,5mm modded stock carb (std 19,5mm) with a 1,43mm nozzle. I noticed it had stock metal reeds still on, will fix it in the spring. It has standard crankshaft and pistons. The inlet&oulet ports have been risen by about 1,3mm. the engine head is modded to, the pressure is now about 13bars or 27.1 p/sf (std 8,5bar?) And is has a standard exhaust pipe. The gear case has the standard shape also. I had a about 9" - 9.5" X 15" cleaver on, it hadn't really enough blade surface or enough pitch, and the engine rev 6650 (digatron tachometer) and it gave it a modest 36,7 knots (just 42.6 mph). I found a 10" x 17" Radice Tipo hydro mibral prop, would like to have about 6300 - 6400rpm, i will use it from now on.
Wich is the best reeds for this engine? I have thought about boyesen power reeds or then malossi reeds. Are the 13bar pressure in the cylinder too much? And are the intlet&outlet ports in the engine too high? Could i get more power with modding the standard pipe? Is there any point with making a nosecone on the gear case? I already have external cooling water inlet. Is there anything else i can do? I will drive on pump fuel, wich is pretty good i Finland (98 or 99okt)
http://www.boatracingfacts.com/forums/showthread.php?t=13813
So, I got one a boat called TG Special, made in finland by Tage Gustafsson back in the 70s, it's V-type boat that is 4 meters long, about 1,8 wide, weights about 43kg/94.8pounds (without engine and driver) and got quite big wings and a Mariner 9.9/15hp eninge made by yamaha in 1986. I got it in the middle of the last summer and some tuning was already done on it.
The carb is a 20,5mm modded stock carb (std 19,5mm) with a 1,43mm nozzle. I noticed it had stock metal reeds still on, will fix it in the spring. It has standard crankshaft and pistons. The inlet&oulet ports have been risen by about 1,3mm. the engine head is modded to, the pressure is now about 13bars or 27.1 p/sf (std 8,5bar?) And is has a standard exhaust pipe. The gear case has the standard shape also. I had a about 9" - 9.5" X 15" cleaver on, it hadn't really enough blade surface or enough pitch, and the engine rev 6650 (digatron tachometer) and it gave it a modest 36,7 knots (just 42.6 mph). I found a 10" x 17" Radice Tipo hydro mibral prop, would like to have about 6300 - 6400rpm, i will use it from now on.
Wich is the best reeds for this engine? I have thought about boyesen power reeds or then malossi reeds. Are the 13bar pressure in the cylinder too much? And are the intlet&outlet ports in the engine too high? Could i get more power with modding the standard pipe? Is there any point with making a nosecone on the gear case? I already have external cooling water inlet. Is there anything else i can do? I will drive on pump fuel, wich is pretty good i Finland (98 or 99okt)