340 w/7.4 mags.....speed?
 

Hey guys, can anyone tell me the speed of a 34 vyper with 7.4 efi mags? Thanks

Re: 340 w/7.4 mags.....speed?
 

need mor info to help.

props?
gear ratio?
RPM's?

Re: 340 w/7.4 mags.....speed?
 

NO, I'm looking at buying one and I wanted someone that owns one now to tell me what they are running(speed wise with these motors)

Re: 340 w/7.4 mags.....speed?
 

what year? makes a big difference on year

Re: 340 w/7.4 mags.....speed?
 

looking at a '99 and a '2000

Re: 340 w/7.4 mags.....speed?
 

I was looking at some pics of '95 and up and they put the steps in and back cut the pad is the differences that I see. At least on '99 and newer had the cut back.

Re: 340 w/7.4 mags.....speed?
 

The boat was originally built as a straight vee from 1996CY to 1998CY. In 1998CY it was stepped. Then in the first half of 2000CY the running surface was modified again. The 2001MY and newer boats should be the best running of the step hulls.

That boat with 454 Mag MPIs (385hp) should run solidly in mid 70's.

Marc

Re: 340 w/7.4 mags.....speed?
 

thanks, I do like the '99 a little better, but I guess that is a little slower hull. Thanks for the info

Re: 340 w/7.4 mags.....speed?
 

So a 496 mags should hit 70 on 2001 vyper?
 

Im looking at a twin 496 mag 2001 vyper will it hit 70? It currently has 28 b4s

An 01 340 will hit 74-75 reliably with the 496 mag (Non-HO) motors at 375 hp. That hull runs 78-82 with HO's at 425 hp. Pretty good hull actually.

One I'm looking at has 28 B4 props 496 mags
 

Is that too much prop? I Heard mention of turning out props out helps especially on 2001+ hull?

The drives are set fairly high on the big PQ's so they have quite a bit of prop slip, therefore can turn a larger pitch prop. My 200 year hull with 502MPI's came with 28p that I could bounce off the rev limiters at WOT, so I went up to 30p. Boat still gets on plane and isn't doggy accelerating and stays barely off the limiters so that seems to be the happy pitch for me.

I did swap my props to spin out and the hull loved it. Easy to try with Bravo drives since they don't care which rotation direction power is applied unlike transmission boats. Just swap side to side and put shifters in reverse to try it. If you like it, just a matter of changing cable pull direction on shifters.

Hows it plane
 

With the props turning out? The one I'm getting has 496mags, also wondering how bad the raw water pumps are too access. Id like to upgrade to harden or something better.

Yes I am now turning my 30p Bravo props outwards vs. factory inward rotation.

on a 380 they are quite easy to access, I imagine a 340 would be a bigger PITA as their engine compartment is much tighter to the front of the engines. One of the main reasons I opted to go 380 instead of 340 when I was shopping. There also seemed to be more 380's available at that time.

I looked at a 340 before i bought my 380. I do my own maintenance and to be honest, don't know how one could physically access sea pumps, or even get to the plugs to winterize a 340. There is no room between the back seat bulkhead and front of the engines to stand like there is on a 380

Just great
 

Sounds like working on it will be fun :(

Well took it out
 

We took it out full load of fuel 160+ gallons and four adults. Did 67. Not sure what it will do with just me the wife and 500lbs less fuel

Well she's pretty slow 63-67. Was doing the iac replacement and discovered flame arrestors were really dirty and throttle linkage binding on starboard, only allowed 3/4 throttle maybe this is why it would not turn 4800 only 4400.

Was able to get 70gps out of her. After adjusting trim limits, replaced both IAC, cleaning throttle bodys, flame arrestors and adjusting linkage on throttles. Rpm increased about 150 so im still 200-250 rpm below 4800. Thinking these 28 bravo s are just a hair too much prop. I would rather have it plane quicker. Maybe some labbing.