How long to reach top speed

thebottomfish · #1 01-26-2016, 11:48 PM

I have a 140hp johnson on my v20, and also a lot of time on my hands since its winter and I've been thinking after riding in a friends Grady White that it takes way too long to reach my top speed.
I start trimmed all the way in, hammer the throttle and trim up...before I lead the horse to water..how long would you estimate your v20 takes to reach top speed?

bgreene · #2 01-27-2016, 04:56 PM

Do you believe your outboard is lugging?

With a 140, assuming it's still producing proper horse power, and assuming your hull isn't holding extra water weight, it should lift to plane, and top out within maybe 30 seconds give or take.......

Maybe take a compression check to confirm outboard power per cylinder.
Best of luck.

thebottomfish · #3 01-27-2016, 11:03 PM

Compression checks out, pulls strong for what it is, my rpms are low which is something I have to play with this year, it seems like props are not effecting my rpms can't get above 5200 even after bouncing around between 17, 15 and 13 pitch props
Takes about 30 seconds to top out so I guess I'm not doing too bad, just would like to see more than 32 mph out of her and get the rpms up

Destroyer · #4 01-28-2016, 02:27 AM

X2 what bGreene just said.

So many things can effect the not only the time it takes to get on plane but also the performance. Boat weight (a gallon of water weighs roughly 8 1/4 lbs). If the foam in your hull is saturated that can add hundreds of extra lbs of weight to the hulls weight.) Cooler filled with ice and soda and beer? Add up the weight from that. Tackle? Number of people, amount of fuel in the tank, extra fuel tank(s). Every pound equals a longer time and the harder your engine has to work. Even the distribution of the weight has an effect. Then there's the engine itself. Is your fuel/water filter clean? Are the carbs clean? Fresh plugs? Lower unit have the proper amount of clean oil? What about the prop? What pitch? cupped? material it's made from? Dents or dings? number of blades?

The point is that it's almost impossible to second guess what your particular boats' specs are. Give us some more info please.

mawshj · #5 01-28-2016, 09:15 AM

tell us about your friends G.W. 32mph is not shamefull with a 140. also the additude the boat goes thu while getting up can make the experience seem way different. ie the hull can rise gently straight up or it can nose up then slowly return to level. often depending on your trim of the motor

bgreene · #6 01-28-2016, 09:18 AM

Bottomfish.........I believe a strong 150hp on V20/21 runs top speed around 36-42 mph depending. The late 90's Evinrude 150 loopers were more like 165 hp at the prop, and I believe the Merc's also in that range.

I suggest you consult with a long time Evinrude dealer/mechanic to discuss how your year 140 performed and such. In my area, Eddie at J&J Boat is 2nd generation Evinrude master tech and I'm sure would be happy to speak with you on phone. 856-456-0102

32 mph may be close for the state of your outboard and hull, but the low rpm suggests other factor at play....

THEFERMANATOR · #7 01-28-2016, 09:40 AM

Try another tach. That engine NEEDS to reach 5600 rpms wot for it to perform properly. the 88 large bore is a bit more forgiving than the earlier small bore engine, but they're all sensitive to propping. I know my 86 with just a 2 inch pitch change in props could go from topping out at 5900 tpm's and 53 mph, to 5100 rpms and 40 mph on the bowrider i had it on. Propping is key for a big v4 looper to run properly.

thebottomfish · #8 01-28-2016, 08:51 PM

I'm using a brand new omc tach so I'm really hoping that's not it, I might get one of those tiny tachs as I hear they are pretty darn accurate just for testing purposes.
I have tried a 13.75x17 ss prop, 13 7/8x15 aluminum prop, 13.75x13 ss prop, all 3 blade props and they all read 5200/5100 rpms
I rebuilt The carbs at the beginning of the season, new spark plugs link and sync and fresh lower unit oil
The boat is not waterlogged as far as I can tell, this 32 top speed and top rpm is whether I have 4 people and a cooler and full tank or I have just myself and no gas, I might lose 1 mph or so but it's pretty dead on and that's according to gps i don't have a speedometer

The gw was a 21 walk around with a 175 johnson of a similar vintage...I just guess I didn't expect that much of a difference with 35 hp and a similar boat, he also tops out right at 40mph

Destroyer · #9 01-29-2016, 03:11 AM

Hmmm... I know this isn't scientific, but your 15 pitch alum prop and your 13 pitch SS prop are generally considered to be the same for ballpark numbers. Reason being the alum prop flexes more than the SS. A general rule of thumb is a SS 2 inches of pitch lower than an Aluminum will give the same performance. So you seeing nearly the same numbers between the two isn't that far off. But pay attention to what TheFermanator said about your engines power band. If you're actually that much lower in your rpm's then something isn't right.

Since your speed is about what I'd expect for a 140hp engine my first guess would be your tach is off. If you can, try a different one for a test without doing anything else to the engine and see what you come up with.

THEFERMANATOR · #10 01-29-2016, 09:40 AM

I will say of all the tachs I've had, my omc tach was off the furthest of any of them. I was propping my built 225, and it said I was turning 5500 or so, dead where I wanted to be, problem was it didnt sound right, then one day it bumped the limiter. I knew the limiter was 6700, so I hooked up my digital tach, and sure enough it was off almost 1200 rpms at wot. So dont assume it being a new factory tach makes it right. Also, theze tachs are driven off the charging system, so any charging issues can effect them as well. If you have the 35 amp charging system, it is common for the magnets to come loose in them, and cause tach issues.