Rev limiter questions

oregoncruiser

Petty Officer 2nd Class
Joined
Oct 1, 2010
Messages
180
Does my 04 larson 230, which is equipped with a 5.0 GXI Volvo penta setup have one?? How do I know when it kicks in?

Background; I have been working with a prop manufacturer to get me a custom SS 4 blade lab finished prop. In my latest round of testing, I was attempting to see how many RPM's the prop would allow me to run. WOT is listed as 4800-5000. At 5300 I noticed a slight cutout in the engine. Was this my rev limiter? It coincidentally would not go any faster. In my first round of testing, I backed out of the throttle at what I thought was 5400.

I thought all newer boats were equipped with rev limiters. Is that limit 300 over max WOT???

Confused?!?!:confused:
 

kawakx125

Seaman
Joined
Aug 10, 2012
Messages
70
Re: Rev limiter questions

WOT and your rev limiter are two different things, WOT is with a load (prop) and the range at which your motor will is most efficient. you want the prop to allow your rpms to fall into this range when the throttle is wide open. the rev limiter is there to keep you from blowing your motor up and protect the accessories such as alternator, power steering, etc.
 

Brewman61

Ensign
Joined
Jun 10, 2010
Messages
996
Re: Rev limiter questions

I'm betting you do have a rev limiter, and that's likely what was causing the slight miss at 5300. Your WOT range of 4800-5000 rpm is your target, not a hard rev limit. As you've seen, you can exceed this range if you under prop, or shove the throttle with the drive disengaged, etc... , the rev limiter kick in to keep the engine from running over it's limit. Not sure how far over the upper end of the WOT range is your red line. Now that you mention it, I don't know what my boat's red line is either. Also, your boat's tachometer could be off by a margin so the 5300 or 5400 your tach was indicating might be off.
 

Tail_Gunner

Admiral
Joined
Jan 13, 2006
Messages
6,237
Re: Rev limiter questions

Your rev limiter is preset at 4950 rpm. Your tach is off by 250 rpm at 4950 it will shut off the fuel supply creating a lean burn so do not spend much time there. Vortec engine's run out of air at that point..(head cam design) so prop to 48-49...It sounds like a minute miss at wot.
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: Rev limiter questions

The rev limiter is an internal part of the ECM, it's set to stop fuel injectors from working until the rpm is at or below the set limit. It's normally set to 200 rpm over the max rpm of your engine range, in this case 4600 to 5000 rpm. Which would make your rev limiter starting at 5200 rpm.
 

QC

Supreme Mariner
Joined
Mar 22, 2005
Messages
22,783
Re: Rev limiter questions

Good thing all posts are in agreement as always . . . :rolleyes:

TG,

Where'd you find 4950? Seems odd to be lower than recommended WOT range ;)
 

Tail_Gunner

Admiral
Joined
Jan 13, 2006
Messages
6,237
Re: Rev limiter questions

Good thing all posts are in agreement as always . . . :rolleyes:

TG,

Where'd you find 4950? Seems odd to be lower than recommended WOT range ;)


My laptop of course uisng a mefiburn program....But he does have a v8 and most importantly the Oracle has spoken....And so it is...;)..Hey 50 isnt bad its a monday geesh...:p
 

oregoncruiser

Petty Officer 2nd Class
Joined
Oct 1, 2010
Messages
180
Re: Rev limiter questions

So.....I understand and agree that the Tach could be/probably is not completely accurate. 5200 sounds correct since I was reading 5300+ or - when I was feeling the 'miss'. Okay, so I feel reasonably sure I understand this.

Talked to my boat mechanic today, and he will run a tach check on it when we winterize(Yeah I said it!!!! suck suck suck) in a few weeks.

My plan is to prop to 4800, prop guy assured me he could take all factors and plug them into his 'program' and create the perfect prop. So far 2 runs, and were still overpropped. On the plus side, I really like the feel of the SS prop. I'm sending it back to be re-worked, and hopefully we get it closer.
 
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