what limits RPM?

**Raceman** · 03-06-2003, 08:53 AM

"I live in Florida so my vote may not count."

It counts & counts & recounts..............................

**mercpower** · 03-07-2003, 10:06 AM

Ok, guys, wasn't trying to start a feud, before I bought a late 80's model v6 merc 200 I just wanted to know what limited rpm and if there was a way around it. I can say that I have learned a lot in this thread, thanks for your help! And entertainment!!!

**us1** · 03-07-2003, 10:27 AM

Nothing in the engine will limit your RPM except the port timing. After about 6500 the power will drop off very fast. Some times this phenomenon is mistaken for a rev limiter.

**BarryStrawn** · 03-07-2003, 11:02 AM

Originally posted by us1
Nothing in the engine will limit your RPM except the port timing. After about 6500 the power will drop off very fast. Some times this phenomenon is mistaken for a rev limiter.

I can think of several mechanical components that will limit RPM when they get tired.

**us1** · 03-07-2003, 11:34 AM

Thats true but am think of a motor without problems.

**mercpower** · 03-07-2003, 11:47 AM

ok, now how would i go about changing port timing

**BarryStrawn** · 03-07-2003, 12:06 PM

Yes - I was trying a little humor. Fishin motor parts with race porting would rather quickly limit the RPM when the piston or rod bolts came apart.

**us1** · 03-07-2003, 12:28 PM

You would need to install 6 steel sleeves and run race pistons. It would cost a lot of money. You would be better off finding a Bridgeport block to keep the costs down.

**KEVIN NICHOLS** · 03-07-2003, 12:38 PM

your foot and port timing are the main factors here......

**rob vaughn** · 03-07-2003, 07:18 PM

I can get you a name of the person that can do the performance work for you.

Not sure where you are from but if interested......

**Pop-O_826** · 03-07-2003, 09:16 PM

Rob's right, we've been running this setup since 1990, and had no problems at all. Just run the motor a little on the rich side and it'll stay together.

**Capt.Insane-o** · 03-07-2003, 10:11 PM

Creeping Jesus how'd this thread get so complicated?

LMAO! Like a bunch of fuc%ing politicians! HAHA!

**us1** · 03-07-2003, 11:45 PM

**O/B Dude** · 03-08-2003, 01:31 AM

Everytime I wanted to throw my 2 cents in, Greg Moss, US1, Raceman or sombody else beat me to the punch.

You can make a 2.4 v-6 scream. I revved my ole warmed over 2.4 fishin motor to 7500 on a regular basis. But if you dont raise the port height, its only gonna make enough power to rev only so high under certain load conditions. Small light boat with a small prop will get more R's than a heavy boat with a larger prop. Port height is kinda like a cam shaft in a 4 stroke motor. If your cam is designed to make power up to 4500 rpm, and you get to 5500 rpm, there aint no limiter, it just dont make enough power to rev higher than that under load.

**Talon2.5** · 03-09-2003, 05:34 AM

HAHAHAHAHAHA what the hell happened in this one man it went all over the place hehehehehe

US-1
Tmerc25
Greg Moss
raceman
O/B dude, thank god things arent really this difficult huh

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