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Heymow - Lawnmower Racing Forum
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Max RPM
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Topic: Max RPM (Read 5524 times)
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mowterin'
Newbie
Posts: 14
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Max RPM
«
on:
July 10, 2006, 12:52:38 am »
Hello all, what do you think the max sustained RPM my 16 HP I/C opposed engine could handle, just tryin to figure because i only have 1 gear in my pearless, and im doing pulleys for MAX speed. its not for competition or anything. thanks
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mowdak1
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Posts: 4349
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Max RPM
«
Reply #1 on:
July 10, 2006, 01:18:38 am »
About 4500 to 5000 RPMs
then your valves are going to start floating.
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Rocky Thomas ~ #693 ~ NDLMRA
North Dakota Lawn Mower Racing Association
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Negrey
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Max RPM
«
Reply #2 on:
July 10, 2006, 08:00:49 pm »
mowdak1 would you mind explaining what valve float is and what the problem is with floating them?
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Evan
mowdak1
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Max RPM
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Reply #3 on:
July 10, 2006, 09:09:55 pm »
Actually wikipedia does an awesome job of that Suburban_12...
http://en.wikipedia.org/wiki/Valve_float
http://en.wikipedia.org/wiki/Tappet
And, although the second link there dwon about paragraph 4 indicates that "engines over 20,000 rpm can still exhibit valve float." The definition there assumes high RPM Race Car engines, Lawn Mower Engines can see this tendency at far less rpms.
If the valves fail to remain in contact with the cam lobe, that essentially leaves your valve open when it should be closed, thus you lose compression and the engine slows to a speed where the valve train can keep up.
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Rocky Thomas ~ #693 ~ NDLMRA
North Dakota Lawn Mower Racing Association
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Negrey
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Max RPM
«
Reply #4 on:
July 11, 2006, 12:06:40 am »
Thanks for the information mowdak1
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Evan
mowterin'
Newbie
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Max RPM
«
Reply #5 on:
July 11, 2006, 12:57:53 am »
thanks for the info. you guys seem to know everything!!
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mowdak1
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Max RPM
«
Reply #6 on:
July 11, 2006, 12:59:02 am »
I just know how to work search engines... I really don't know a whole lot about mowers! Just ask Squidd and George they have to straighten me out all the time! :wink:
On a 16 hp opposed your subject to find problems with them if you push them too hard also. A lot of guys are running them with luck, especially our friends north of the border, but those that do encounter problems indicate the rod is the weak link in the opposed engine. There aren't a lot of aftermarket parts available out there for them either. Maybe Matt and a few of the other Canadian Racers can point you in the right direction on your build.
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Rocky Thomas ~ #693 ~ NDLMRA
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matt25001149
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Max RPM
«
Reply #7 on:
July 11, 2006, 08:46:48 am »
lol thx Rocky u gotta gear those motors so there just winding out at the end of the turn they cant hold onto high rpm for more than a few secs if that cause theyll either cease up or blow and dont be afraid to use expensive oil in it either it helps theyll last longer iod say they prolly only rev to abot 5000-5500 rpm no more and theyres barely anything u can do to them mainly caus no one makes cams for them or lighter flywheels im sure the double springs from E.C. would work but there really is no reason to get themthey are flatheads so id say shave the heads and advance the timing a lil bout all u can do with them
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#87 Outlaw
Western Ontario Outlaws
mowdak1
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Max RPM
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Reply #8 on:
July 11, 2006, 09:37:47 am »
One of the joys of being in management too long Matt... over time you acquire the ability to recognize talent and delegate authority! :mrgreen: :wink:
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Rocky Thomas ~ #693 ~ NDLMRA
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George Herrin
aka SUPERMAN
Superman
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Max RPM
«
Reply #9 on:
July 11, 2006, 09:51:06 am »
Aggh But Precision cam can regirnd your cam to anything you like!!! Then you will need them dual springs!!! :twisted: :wink:
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George Herrin #6
Indian Power.. You gotta Go big to beat em or Go HOME
8 time ARMA National Champion
4 time USLMRA National Champion
Retired from BP
www.herrinmowersports.yolasite.com
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My other racer is a 1/5th scale Dirt Late Model!!!!
matt25001149
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Max RPM
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Reply #10 on:
July 11, 2006, 12:20:30 pm »
o lol well nvm then i guess u can have a cam made lol for got about regrinds
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#87 Outlaw
Western Ontario Outlaws
fox_racin4
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Max RPM
«
Reply #11 on:
July 11, 2006, 02:00:20 pm »
ive ran mi opposed reved up all the way and it took it liek nuttin theres a guy who said he tried to blow one up and he had STP oil traetment in it and it didnt blow at a race he was trying to figuer out why it wasnt reving over 5000 so they are strong motors if u know what ur doin
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#4 super modified
SOLTRA
Red Horse Racing
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Max RPM
«
Reply #12 on:
July 11, 2006, 06:18:47 pm »
huh? :?: :?: :?: :?: :?: :?:
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Wheel Horse of Course!!
fox_racin4
Turf Warrior
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Max RPM
«
Reply #13 on:
July 11, 2006, 10:44:48 pm »
i had a opposed and it took teh rpms really good and never blew
there was a guy at the past race that said in one of hte races he ran that he couldent figuer out y he couldent get it to rev over 5000 and he also said he ran stp in one of his engines an ran it for a few years and never blew it up
if you kwno what ur doin its an awsome motor
is this any better ( hurkerd on funiks werked 4 me)
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#4 super modified
SOLTRA
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