312?
 

what are the speeds outta 312 with 454/310's mpi's 454/mags 385 efi's i believe and with 502's?

I had a 312 with 502's. Saw 74 GPS a couple times but 71-72 most any day. 454/385's should be 2 mph slower while the 454/310's will likely be 65 under the best of conditions (probably a little slower).

fixx
 

a friend just traded his in at shoegrens,the boat did like stated with the 310 efi's 65mph,,saw 67 once with no fuel..with the 5 blade maximus props the fastest was 62 mph but would plane out and stay at 2100 rpm's at 20 mph..

what else can you tell me about this one, thats the one I'm looking at

Is that the one on Shogren's website now? Thought those were the 385HP mags.

Mercury made 454 MPI's and 454 Magnums. Those are MPI motors......completely different and not suited for upgrades either. They make 310hp.

I have the 454mag mpi's 385 hp, 70mph on the GPS. Great boat but does not like to go slow. If you want to go 25 mph, drives must be tucked in and you must use some tabs. My only suggestion is to look for a boat with full hydraulic steering and the big merc tabs. You will have no regrets.

good numbers I'd like to have

Fixx
 

the boat was lift kept,,stayed in the water only on the weekends thenput up in a warehouse..winter it was kept in the same warehouse and is heated...the 5 blade props that were on the boat are available..the guy that owned it changed the oil in the engines every 30 hours with mobile one 15w50. the drives were just servised,,he also still has the silent thunder platform which he wants to sell...

I have a 97 312 with 454 mag mpi's I added offshore exhaust ditched the silent thunder, and added a vortech breather.. I run 72-73 on GPS.. however my prop slip on my Bravo-1 30's are at 17% I think if I could get the slip down may paick up a mph or 2. RPM is 5100-5200 ( had the ECU bumped a little too)

I have the 310 HP 7.4 MPIs with 28P 4 blade merc props and 1:65 drive ratio. Low 60s is consistent. 64-65 when the stars align just right. Ditto on the "does not like to go slow comment" It does not really get on top until 45+. It will run all day in the 50 to 55 range.

As mentioned by others, you have to use tabs and trim in in the 30 to 40 MPH range our it will tend to get unsettled easily and porpoise. The throttle is your friend on this boat - use it to drop and lift the bow to run smooth in chop or swells/wakes. A well timed blip of the throttle makes all the difference when riding the rough stuff. I think prop selection could help a lot with the ride issues, but I have not played around with that.

Am I happy with it? Yes. It has been rock solid & reliable. Would I like more power? Who doesn't - :drink:

Had a 97 with 502s and she went low 70s pretty much how she was loaded, good boat, just need a few more feet, you know what I'm talking about.

Since we are talking about 312's and speed, I have a question. On another site someone asked about the speed and desirability of a 312 with 496's and Duoprop Volvos.

My understanding is that any dual prop design is slower on top end than a single prop and that the Volvo Duoprop drive, in particular, has a poor underwater profile and is less fast than a Merc Bravo3. Is that correct?

I believe so, who's running a 312 with 496's what do you get?

Not sure about hydro-dynamics but some of those VP duo-prop drives are damn near bullet-proof. There is a guy in the upper bay running a pair of Volvo (Innovation) 600's with duo-props on a 382 and absolutely loves the set-up. I think he claims about 80 in it and a number of local verify it.