pq 340 viper -99
 

anyone i need help whith top speed and rpm on this boat.my engines 2x502 mag mpi. how many hp has this engine and whith this egines top speed in this boat .micke

You have 425 hp Top speed will be 69 to 72

Aren't 502 mag mpi's 410 hp?

But I think your top speed prediction for a non stepped Vyper is dead on. :cool-smiley-011:

okej do you mean mph or nots beacose i read some where that it will go in 80 mph thanks for all help..

i am realy confused both my engine are fixed thea are like new . and i had them stroked to 540 and tok a test drive yesterday .hade problem left engine miss when we go 4800 rpm have order new cabels ingnition .right engine 5300 rpm i understand that left engine must go like right but we run only 60 gps nots .can left engine bring the right down so mutch. now after i hade them fixed and stroked hoping that my new rpm shuld be like 5600-5900:) hade hope i order new 30-32" propps at bblades :)

Mac, nice the hear from you. Thanks for the correction on the 502. However on the hull on my previous 1999 Viper was an early model and had the steped hull. Not the corrected step but the original. It had the HP 500'S and did 75 - 77 top end.

I would estimate mabey another 2 MPH if this 502 Viper had the newer hull but from what I know there were not many 1999's that had it.


Say I have seen a fe pictures of your new boat, looks fantastic!!!!! Did you ever find out if someome bought your Viper?

i dont no if you talk whit me ? or whit mac:) but i have a film on my boat www.bruket.nu/porsche911 then move the pointer over the picture then FILM com up chose the second film right click save as. i have steeps att my hull but maby you see it att the movie:)

I believe Merc listed them at 415 HP.

Micke,
You said the motors are stroked to 540 cubic inches? Is that correct?
And you are asking how much HP they have now?
The motors are Fuel injected (mpi)? IF yes then someone would have had to re-map the fuel injection for the larger displacement. This person should be able to tell you how much HP.
If the motors are not stock (Original). alot more information is needed to determine horse power. Any head work done, cam lift & duration specs, Fuel injection tuning? Who did the motor work?

5900 rpm sounds like alot. Usually stroked motors don't want to turn faster. Sounds like it needs more prop. 30-32 better.

As far as one motor turning 4800 and the other turning 5300 rpm, I would think that would cause a huge negative effect on your performance. 60 knots is 69 mph. using 1 knot is 1.15 mph.

just my opinions, I am NO expert

Get that thing dialed in, tell us how fast it goes.

hello shawn. i have big poblem to spell beacose i am from sweden but i gone do my best. i get the new parts tomorow
ACCELL SPARK PLUG WIRES etc.. new test run .and i gone check my engine spec and com back at this thanks for the help so far :)