Re: rev limter
 

not certain what i said that implied any and all advice not appreciated. any and all advice IS appreciated. was trying to offer more detailed infomation that might assist those more knowledgable than myself in coming to a conclusion.

suggestion was made that boxes may not be correct and is, of course a possibility.... was just pointing out that llikelyhood of that , given the physical evidence, less likely than more and that problem , if any, may be elsewhere.

for the record you are talking to someone here that has , essentially zero experience in the marine industry but 30 yrs experience in the race car engineering and manufacturing industry.... am asking questions and posing problem in a technical scenario/forum and simply applying my own engineering logic to any proposed solutions.... thats what discussion and problem solving in an engineering sense are all about....

i thought.

Re: rev limter
 

Take a look at your hull. Using a 4-5' straight edge, make sure there is no hook or rocker in your hull. I have seen the exact same thing when a rocker developed in the hull about 4' forward of the transome. Right where Myco left a space for lifting straps.

Re: rev limter
 

The info provided was to eliminate one possible cause and to address your title and problem as stated of hitting the rev limiter. Nothing but the ecm controls the rev limiter.

You can eliminate that from your list of potential issues 100%by following the suggestion.

Another way is to do as another suggested by putting smaller props on and seeing if it revs more.

Look on the drives and see what gear ratio is stamped on it and then turn the engine over and check it.

Re: rev limter
 

Did you ask what props to run over on the Cig. forum or at Prop talk?

I'd try a set of 23p Mirage or Mirage+.
Spin then out, then try spinning them in.
I realy don't think a 38' Cig is much more than a 60mph boat with twin 415HP/502s

Re: rev limter
 

lets talk about the props for a minute..... people keep saying " less prop"
and that was the first thing the local guru here said as well and im not argueing.... im looking to understand this at a basic level. now on the cars that is analagous to shorter gears... which will improve acceleration but not necessarilly add more top speed ( unless you were geared very bady to start with) . now a 22 prop is about 8 % less prop than a 24 which means i would need 8 % more revs to break even... which for the sake of this discussion is about 375 revs.... so that gets me to 4900 give or take for the exact same speed. question... has anyone actually see a dyno sheet for one of these motors ? is there so much more power at 4900 to then allow the boat to get thru the drag limitation then there was at 4500 ? serious question does anyone know what this power curve really looks like ?

Re: rev limter
 

Don't compare your 11,000+lbs boat to a car. Compare it to a tractor-tailor going up hill.
Yes, dyno testing would indicate that a stock 415HP/502MagMPI makes about 400HP at 5000rpm...
Yes, assuming your engines are 100%, you absolutely need smaller props!
Prop the boat to max out at 4800-5000rpm; at 4500rpm the engines are lugging.
If you want to stay with 4 blade props then try 22p Bravos; you will get the motor to 5000rpm and gain 1-2mph.
If you want to go 3-4mph faster on top, then run 23p 3 blade Mirage or Mirage +.
And like I said in my earlier post, test spinning them out and spinning them in.
You may loose some mid range speed with 3 blades, but the boat will go faster.

Re: rev limter
 

i am sure i can get my hands on some 22 x 4 to try and will do that for sure. please educate me on the rotation issue.... whats the concept about spinning them to center or away ?

Re: rev limter
 

update.... prob was pilot error. due to inexperience was running with drives full down. cig forum members suggested trimming drives out and that was the magic trick. boat now has lots of revs and 62 mph at first go at dialing it in.

learning more by the minute... and thx