1992 merc 4.3lx wot rpm

[Pushrods]

I will be test driving and hoping to buy a '92 Larson 190BR this week. I understand the LX model of this engine has a 4BBL weber carb and is rated about 20 HP higher than a regular 4.3 of the 2BBL flavor. I assume the 20 or so more ponies come at a higher RPM than the 4800 or so of the 2 BBL version of the 4.3 for that year. Im interested to see what the 14" 19P prop will do at WOT but do not want to overrev it. I have heard the max horsepower is about 5200 but don't really know if that is correct or not. Does anyone have accurate information on what rpm is for max hp for this engine?

Thanks,
Pushrods

 

[180shabah]

Re: 1992 merc 4.3lx wot rpm

Merc max RPM for the 4.3's was 4800 (I believe there may have been some that were listed at 4600). Whoever told you 5200 has never read a manual.

The additional power comes from more airflow not higher RPM.

Good luck with the test.

 

[achris]

Re: 1992 merc 4.3lx wot rpm

4.3L (2bbl Mercarb) was 175hp (WOT 44000-4800).
4.3LX (4bbl, some Rochester, some Weber) was 205hp (WOT 4400-4800).

HTH,

Chris.........

 

[Pushrods]

Re: 1992 merc 4.3lx wot rpm

Thank You for the info, I think I am going to pass on the boat I had in mind. I think I will be looking at a later model boat but with the same 4.3l just newer and understand they are 190 HP for carb and 220 for MPI. Im thinking because of roller cam and vortec heads for the increase. I assume RPM max will be the same at 4800..

Thanks again,
Pushrods

 

[180shabah]

Re: 1992 merc 4.3lx wot rpm

Both engines have a roller cam and vortec heads. That bump in power comes from better breathing through the intake manifold, throttle body etc.

I also think the 190hp is a little under-rated. I have no data to support this belief, but they do seem to perform better than they "should"