SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: firefly on April 06, 2007, 11:26:48 AM
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Just curious to see what RPM's you guys get your boat up to and what the "safe" level is. I understand that most, if not all our motors are built a little diff. i.e. diff performance parts, ford, chevy, olds.
Last weekend i got my 460 up to 4800 rpm, she was really moving but im worried that this might be a little to much and that i might be creating more damage then the fun is worth. She seemed like she wanted race around at 4000 all day long. My best guess was that at 4800 we were probably going about 60-65mph with 2 people on board and less then half fuel and no other gear in it.
My 460 is a Hardin Marine engine with Bassett twisties, Holley 750 carb, and Edelborck performer rpm manifold. As far as internal performance enhancements i have no idea, the guy i bought it from hadnt said anything to me about it. I run a Berk jc-a pump. It does have a stock ignition system in it.
Do these numbers sound right/add up to you guys?
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Yes they sound OK for a stock motor. I would get a cheep hand held GPS. It will help let you see where you are truely at performance wise. I have seen 15mph gains just in pump work.
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Emanon, what kind of pump work would help out?
Also, i was thinking about putting MSD wires, MSD rotor cap, MSD-6 box, and a Blaster coil on? I figured it was something easy for me to install for around $300 and would/could help out, what do you think? If i did, what kinda plugs should i use and would i have to change anything with the engine by putting that stuff on? i.e. timming or anything like that?
Back to my original question, is 4800 rpm to high?
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Personally I like less RPMs but that is my personal choice. I also run a A3 impeller. The BBF makes it peak Torque at about 4K in stock dress. So a A2 impeller would help in your case, it also will save gas ! A sport loader would help increase efficency a bit, and they can get you up to 3mph gain.
Unless you need new ignition I would not change. But a MSD ready-to-run distributor is worth its weight in gold. No box, no BS just one real good dist.
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Emanon, what kind of pump work would help out?
Also, i was thinking about putting MSD wires, MSD rotor cap, MSD-6 box, and a Blaster coil on? I figured it was something easy for me to install for around $300 and would/could help out, what do you think? If i did, what kinda plugs should i use and would i have to change anything with the engine by putting that stuff on? i.e. timming or anything like that?
Back to my original question, is 4800 rpm to high?
i have the 6 box on my race boat only for the rpm limiter. on the day cruiser i have the ready to run as jim suggested, however you can put a rev limiter on that too, just more $$$.
the spark is hotter aka more effecient so testing with different plugs would probably be necessary.
i dont think 4800 is too high as long as the motor was prepped for it. do you have an oil temp gage?? oil temp will tell you a lot. how much does your oil pan hold?? heat will be the enemy with rpm.
on my lake boat i dont have a prob spinning 5k, race boat no less than 5k and the rev limiter is set at 7k, but mostly between 5 and 6k.
just my .02 ralph
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i dont think 4800 is too high as long as the motor was prepped for it. do you have an oil temp gage?? oil temp will tell you a lot. how much does your oil pan hold?? heat will be the enemy with rpm.
Keep in mind that not only will high rpm create higher oil temp, so too, will increasing the load on the engine by increasing impeller size. Going from an A to an A3, for example , will seriously increase the load your engine sees at every rpm across the board. For a "stock" engine this could be a recipe for disaster.
The suggestion to run an oil temp gauge is on the money.
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rwyyattb,
I dont know if my motoe was prepped for it. I do have an oil pressure gauge, not a temp gauge. The pressure gauge stays at 80p.s.i. idle through 4800rpm, it does go up a bit at higher rpm's though. As far as the oil pan, the previous owner did install a Milodon, low profile 10qt. oil pan. The oil was just changed 3 weeks ago with only about 2 hours on the change.
How hard would it be to install a oil temp gauge?
How much did you guys pay for the ready to run distributor? Certain type i should get?
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oil temp gage is easy as long as there is a bung in the pan, if not you can use you drain plug hole and just remove the sensor instead of the drain plug. kinda ghetto but it works if you dont have the bung.
i got my rtr at rex a couple of years ago and i think with plug wires it was 450
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my 440 ford spins 7200 at 102 mph with an A impeller i was told i could not do it with out a blower but proved them wrong with big cubes u cant spin real hard rpm but with small u can spin the shit out of it
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my 440 ford spins 7200 at 102 mph with an A impeller i was told i could not do it with out a blower but proved them wrong with big cubes u cant spin real hard rpm but with small u can spin the shit out of it
:o :o :o :o just another bad ass FORD ;D
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my 440 ford spins 7200 at 102 mph with an A impeller i was told i could not do it with out a blower but proved them wrong with big cubes u cant spin real hard rpm but with small u can spin the shit out of it
I love it when I accomplish something that people tell me can't be done. It gives me a hard on, woops too much info.. In the Navy they asked me to fabricate a way to hang a firehouse off the side of the superstructure. I welded 4 brass bolts to the aluminum superstructure using an arc welder with an aluminum welding rod - ask a welder - "it can't be done". In 1984 I took my 1984 Ford Ranger down to Moordrop, a axle specific lowering company in the Bay Area specializing in I-Beam axles. They told me "it can't be done on the Ranger". A month later I went on a 6 month tour called a WestPac and when I got home I installed my lowered Ranger front axle that "couldn't be done". About 3 months later I saw in a Hot Rod magazine a Ford Ranger that Hot Rod had contracted out to have the front axle lowered, or maybe re-made - I don't remember which.
What's the topic of this thread again? ??? ;D
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I run my 460 up to around 5600 RPM's It has been fully machined though. Internally balanced, heads reworked, etc. I think I am pushing the limit with stock crank and connecting rods. I get the same 80 psi from idle on oil pressure too.
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I wouldn't worry so much about the oil pressure verses the oil temp. From what I've read marine duty engines have a much higher cylinder temp than car duty engines which would be reflected in the engine's oil temp. I had a 327 that had about 8 psi oil pressure at idle but it ran fine and never gave me any "oiling issue's".
Check your PM's!
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dam straight ralph ; >:D dont have to worry so much about the oil temp if u run a good synthetic
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Quote Just curious to see what RPM's you guys get your boat up to and what the "safe" level is. I understand that most, if not all our motors are built a little diff. i.e. diff performance parts, ford, chevy, olds.
My boat runs at 4900 RPM's and I think my impeller is holding my engine back. I am running a B cut.
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The Berk B impeller should allow a stock engine to run about 5K or more. If any mods have been done you should see about 5100 or so. The Berk A with a stock engine should be right around 4400-4700.
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It's a Hardin Marine 460 with 10.25 to one compression. It also has a Wiand tunnel ram with dual 750's with vacuume secondaries. Should I change my impeller?
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Emanon,
What do you consider a stock engine? Im guessing i shouldnt push it past 4500 to keep things from breaking and keep it reliable, cause thats what im going for, realiability. I am gonna go with a ready-to-run distributor from MSD here in the next couple of weeks as you suggested.
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It's a Hardin Marine 460 with 10.25 to one compression. It also has a Wiand tunnel ram with dual 750's with vacuume secondaries. Should I change my impeller?
Are you going to use this at the lake or race ? How many RPMs do you want turn ? How many RPMs does your cam want ?
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Are you going to use this at the lake or race ? How many RPMs do you want turn ? How many RPMs does your cam want ?
I plan on running lakes and rivers. Don't really have a urge to race , But don't want to be the slowest of the bunch either and I have no idea what my cam wants. i also failed to mention that I am running a full MSD ignition.
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Most mild performance 460 BBF make tons of torque below 4600rpms. I think your impeller is allowing the engine to spin too high, in turn not giving you the efficency that you need for a lake / river boat. Again My recomendation is going with a A2 impeller. You will end up right about 4600rpms maybe less but it will create more thrust at that rpm than you have now at 4900rpms with the "B".
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Thank you very much for your opinion , When I rebuild my pump I will take that into serious consideration.