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CUTTINGRASS
Dodge Dakota
11/07/2001
16:06:55
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 Subject: ENGINES
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Message:
Got a 13 HP enduro OHV, anyone know what the top RPM is? I wnat to take it to about 17HP and increase the top end breathing ability. Plus, I want to make sure I get most of the A/F mixture burned to keep emissions down.
ANy ideas?
Engine has an adjustable carb and stuff.
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Clevite 77
Dodge Dakota
11/07/2001
16:11:05
| RE: ENGINES
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I take it, it's not a Dakota??
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brianldm
Dodge Dakota
11/07/2001
17:56:48
| RE: ENGINES
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Once your finished try dropping it into a ol' Geo Metro and go race some imports. Anyways ....
I dont have a friggin clue.
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alex
Dodge Dakota
11/07/2001
18:26:37
| Kick Some Grass......
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Mill the head for compression, pocket port around the valves, bore & stoke, larger exhaust, run alcohol. Try K&N's new Big Mouth X-Treme Yard & Garden Air Cleaner Lid on your filter. Maybe an IAT adjuster. Definitely want to take the blade off the output shaft. Helps it rev up quicker. Like removing the clutch fan. Hey- try removing the clutch fan. Is yours the 5-spd or the automatic? I heard the 5-spds come with more power from the factory. I don't know. Take it to the dyno to confirm the 13hp number. That's just the factory rating. They may be sandbagging to keep your insurance down. Remember the 60's when the Hemi was rated at 425 hp at 4900 rpm? Well, it was making that much power at 4900, but the engine would rev to 6000 rpm. At that point, it was making 525 hp. Sneaky, eh?
Well, good luck w/ your project. Let me know if you have any questions.
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Snapper
Dodge Dakota
11/07/2001
18:43:36
| RE: ENGINES
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Actually I already undertook this project, and its well worth it. by upping the compression and dyno tuning it I actually shaved three and a half minutes off my yard lap time. Make sure you dyno it b/c the 13 is flywheel horsepoer, mine actually only made 10.8 output shaft or blade horsepower. The best thing though would be to only mow at night and on a low humidity night, then your 1/4 yard times would be way down. Check out toroperformance.com and snapperracing.com they have all the mods you need.
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cuttingrass
Dodge Dakota
11/07/2001
20:04:58
| RE: ENGINES
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Ok, I dyno'd the motor, and boy it only came up to 11.1 HP at the crankshaft...I got cheated nearly two horses.
I took off the stock muffler and went with a modified expansion chamber (riggged) from a Kawasaki H-3 1970's vintage.
I found out it was reving to 2780 RPM per tachometer. Adjusted the guvnor so it revs to 3850 RPM.
Just those two changes netted me about 2.6 HP so now I read 13.7 at the crank.
Carb work and air intake will be next.
Does anyone think porting the valves would help?
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snowman
Dodge Dakota
11/07/2001
20:37:59
| RE: ENGINES
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Engines are air pumps. Anything to help them breath helps. Also , getting 15 hp from 5 hp briggs is common. The same trick should work for you. The trick? Over revving the engine by installing titanium rods.
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Bruce P.
Dodge Dakota
11/07/2001
20:48:33
| RE: ENGINES
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Are you are talking about a 2-stroke engine? (I am assuming this because of your mention of an expansion chamber from a Kawasaki 3-cylinder 2-stroke.)
Power can be found in proper design of the expansion chamber. When properly executed... the RPM at which POWER is produced will be a VERY narrow area. (but your power will be awesome while the engine is "on the pipe")
I suggest you find a book on expansion-chamber design. The placement of each diamater change in an expansion chamber actually SUPERCHARGES the engine by stuffing extra fuel-air mixture into the combustion chamber just before the piston-port closes.
The "stinger" (end of the pipe) actually creates a vacuum at the exhaust port just before the piston opens it so the engine does not have to push the exhaust gasses out.
Expansion-chamber design is part science due to the physics of sound waves.... luck is involved too ;-)
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R/T
Dodge Dakota
11/07/2001
23:00:05
| RE: ENGINES
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Message:
Don't forget to get a 50" moving deck the bigger the better I always say. Buy some high titanium, light-weight blades and your yard will be cut in half the time. Don't forget to upgrade that cheap plastic steering wheel with a 3 hole racing spoke. Some fat 13" rims do wonders on the grass, helps keep the grass fluffy. Rip out the lights since noone drives at night and place some scoops for added air flow.
Your neighbors will envy you on garden day.
JD, Snapper, Murray all make for good mowers.
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toast
Dodge Dakota
11/08/2001
00:24:29
| RE: ENGINES
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Message:
Well i toke my 2000 Crapman tractor and rebuilt the Briggs Intek V-twin. Tore it all down and had the head ported and ploshed and had bigger valves installed. Then i had the clinders bored 30 over and put a Briggs super stock cam in it. Then to match the cam it had the 1.7 roller rockers installed and had the intake manfold ported and polished. Then i put the Stage 3 jet in the carb. and bigger throttle plates. Than after all that was done i put the K&N air filter in it with JBA headers running right out into a straight pipe. Bumbed up the hp from 25 stock to 60hp. I get 2acers of grass done in like 10mins.
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CUTTINGRASS
Dodge Dakota
11/08/2001
08:06:39
| RE: ENGINES
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Sorry to end the discussion but I have since had major engine problems here. Seems Tecumseh deliberatley kept their engines governed down due to piston ring float. Well in my desire to get more ooomph from the motor, I set the governor speed up to 3850 which created lots of ring float and what happened is the oil ring broke and came out of the piston groove. Cylinder wall got scored in a major way so I will have to resleeve the block and go back to square one.
The expansion chamber I rigged up took the place of the muffler, I grafted a small piple from the exhaust port to the chamber and noticed that the motor revved much more easily and freely.
Stay tuned. Neighbor advised to hop up B&S motors as opposed to techmseh. But I just LOVE that indian head!
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alex
Dodge Dakota
11/08/2001
09:43:54
| Grass Rooster Tales
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Remember the long-horn Ram 413 motor from the early 60's? The principle was that there were pulses that traveled up & down the intake tubes. These pulses were caused by the intake valves slamming shut. If the intake runner was tuned to a specific length the pulse would be headed back down the runner straight at the back of the vlave right as it opened. Sort of a supercharging effect with no super charger. You should install a long intake tube off to the side to get that super charger effect. Also, wrap this tube in dry ice and duct tape to cool the intake charge. I saw an idea on the DML where you can take your Ecco Leaf Blower and strap it to the intake tube. Open up the leaf blower to full throttle itself (you can just hold it in your lap) and tape it to the intake tube. This will get you 1 to 1.5 psi of boost. That combined with the long runner intake design should get you a ridiculuous hp number like 25 hp or 30 hp. How many hp per ci is that? Holy Cow!! Think of the possibilities, here! If you hop up the motor on the leaf blower, you could get more than 1.5 psi, right? Anyone know how to hop up an Ecco blower motor? maybe we can replace the Ecco motor with a Red Max. I hear Red Max starts on the first pull everytime. No questions asked!
alex
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Josh
Dodge Dakota
11/08/2001
11:20:43
| RE: ENGINES
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My tractor stayed at a Holiday Inn Express Last Night. It is running awesome now.
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toast
Dodge Dakota
11/08/2001
21:04:54
| RE: ENGINES
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Hey alax try using the new Echo PB650, most power back pack blower that will out blow any Red Max and does start on the frist pull every time. Also Cuttingrass you are better off junking that peace of crap tecumseh and get the briggs. I am suprised that your engine did not blow a rod running that high, usally that is what most tecumseh engines do if you run them over 3200rpms, you got lucky. You might be paying more for a briggs but you are getting a way better engine, trust me man i work for a samll engine shop and i have had tecumseh engines apart before and they are cheaply built and just poorly designed, they are junk just like fords. Most briggs engines are set from the factory are at 3600rpms and you can usally get alittle more out of these engines with out hurting anything.
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CUTTINGRASS
Dodge Dakota
11/09/2001
08:43:42
| RE: ENGINES
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Message:
THANKS TOAST I'e been doing extensive research on this and the consensus is exactly what you described, Tecumseh just does not like high RPM.
The guy I spoke to last night online said exactly what you said, I was lucky to have not tossed a rod at that RPM
Stay tuned, I am looking at a Briggs to mess with.
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