RPM WOT information CONFUSED

[erick11s]

Hi, I have a Mercruiser engine 400 cyclone year 1985, my problem is that i am confused with the maximum wot rpm of my engine.
The Mercruiser service manual Boatinfo - Mercruiser Service Manual nr. 9 - 1985-1988 - GM V8 Engines said it is 4800-5200.
But the Pirahna propelle company says it is 4000-4600. (See attatchment picture)
This is very important for being able to match my propeller to my top end.

Who should i believe?

Thanks in advanced
Erick

 

[JASinIL2006]

Re: RPM WOT information CONFUSED

Well, you have the Mercruiser specs, or you have the third-party prop vender who notes the WOT values they cite (in red) should be double checked "as they have not been verified." I think I'd go with Mercruiser....

 

[Bondo]

Re: RPM WOT information CONFUSED

Well, you have the Mercruiser specs, or you have the third-party prop vender who notes the WOT values they cite (in red) should be double checked "as they have not been verified." I think I'd go with Mercruiser....

Ayuh,.... I'm gonna disagree, 'n say I think Merc allowed a misprint to slip through,...

Windin' a BBC to 5200 rpms, is windin' it Waayyy to tight for me to believe is correct,...

A motor from Mercury Racin', Maybe,...
A standard production BBC runs 4200/ 4600 rpms, wot,...

 

[Fun Times]

Re: RPM WOT information CONFUSED

The cyclone engine back around 1985 was one of Merc's hoped up versions of High performance at that time.

Jim says it best here, http://forums.iboats.com/mercruiser...400-engine-mercruiser-583511.html#post4021426

And here,

Cyclone's was just a series of engines merc came out with. They were 400,440,and 460 hp. They had 4 bolt main blocks,aluminum high rise intakes,rectangular port heads,forged crank-rods-pistons,and aluminum roller rockers.The 460 hp model was stroked .25" to give it 482 cu. in.'s and 9.2:1 compression. The others had 8.8:1 compression.

V8 Specifications

Setting you target for 4800 - 5000 would be a better/safer choice to make in my opinion.

 

[Tail_Gunner]

Re: RPM WOT information CONFUSED

The cyclone engine back around 1985 was one of Merc's hoped up versions of High performance at that time.

Jim says it best here, http://forums.iboats.com/mercruiser...400-engine-mercruiser-583511.html#post4021426

And here,

V8 Specifications

Setting you target for 4800 - 5000 would be a better/safer choice to make in my opinion.

bingo

 

[achris]

Re: RPM WOT information CONFUSED

Taking all the replies so far into consideration, I looked in some of the earlier manuals, to see if a misprint might account for the higher WOT, but no, all manuals with the hopped up 454 spec 400 to 800 more than a 'standard' 454. All things considered, I'd take the Merc spec as gospel. 1985 400 Cyclone, 4800 to 5200 rpm at wot. Interestingly the idle speed spec also seems quite high, (800-850 in gear)... I suspect there's probably a pretty mean cam in there.

Chris.....
BTW, for those concerned 5200 might be a little high. Merc spec for the Cyclone 460 is 4800-5400rpm...

 

[erick11s]

Re: RPM WOT information CONFUSED

Thanks a lot, for yours comments, I will take 4800-5200, ibelieve the information from mercury it is correct.

Regards

Erick