performance with 150 etec on 20' SF

[htillman]

I've got 150 ETEC on 20 CC and only get 5000rpm. It's a viper 143/4 X 16. Was a 17 but took 1" off - maybe I need to go one more?

[Bushwacker]

Originally Posted by htillman

I've got 150 ETEC on 20 CC and only get 5000rpm. It's a viper 143/4 X 16. Was a 17 but took 1" off - maybe I need to go one more?

The OPTIMUM RPM on all 150 E-TECs except the 2007 and 2017 models is 5500-5600 RPM with a full load and your motor isn't even developing peak HP till about 5300, so I suspect you may actually get more speed with less pitch, plus it will be easier on the motor! (These 2-strokes love to rev!) But before you start screwing around with props, make sure your motor is mounted high enough; most dealers mount them too low! (see my sticky post on this subject)

The Viper is BRP's speed prop, but in my experience it's not very good at hanging on plane at low speed, which is important in a 20 if you run offshore very much or if you run in high traffic areas where you can't always be running 25+ mph! In my experience BRP's 4B Cyclone is a more efficient prop with a great hole shot that will hang on plane down around 12 mph, so it's real nice to be able to run virtually any speed you want with a throttle that isn't too sensitive. I can only turn the 14.5 x 15P version up to 5400 on my Seafari but it's fine since the optimum range on my 2007 model is 5300-5500. You might be able to turn it faster on a lighter CC model.

[kevin.ri]

Originally Posted by htillman

I've got 150 ETEC on 20 CC and only get 5000rpm. It's a viper 143/4 X 16. Was a 17 but took 1" off - maybe I need to go one more?

I Just put on a Brand new 150 Etec on my '73 20sf and I too am having trouble getting past 5100 but I took the prop off my old 150Di which is 14.5x19... I plan on pitching down. Quiet honesty I'm torn between which prop to get.

[Bushwacker]

Originally Posted by kevin.ri

I Just put on a Brand new 150 Etec on my '73 20sf and I too am having trouble getting past 5100 but I took the prop off my old 150Di which is 14.5x19... I plan on pitching down. Quiet honesty I'm torn between which prop to get.

Most dealers seem to mount motors too low, so before you change props check height of AV plate above bottom. Capt. Terry is running a 150 HO E-TEC on his Seafari with AV Plate at 1.5" above bottom and that puts it on top of water where it should be when he's up on plane. If motor is too low, the extra drag will cost you some rpm.

However I think 19" pitch is still too much for a 3B prop. If it's an aluminum prop, a good shop could repitch it get more rpm. What specific prop are you currently running, and what is the most important characteristic you want in a new prop? (i.e., bow lift for maximum WOT speed, stern lift to be able to hang on plane at lowest possible speed in rough conditions, hole shot for maximum acceleration when pulling skiers or carrying a heavy load, or maximum mpg at cruise?) There are different types of props that are optimized for a specific purpose, so you need to figure out what characteristic is most important to you. The Viper is BRP's bow lifting speed prop, but you may have trouble planing below 20 mph with it. The 3B Rebel has very large blades and is normally used on the bigger 3.3-3.4L motors; the 2.6L motor typically can't spin it fast enough on a 20' hull. The 4B Cyclone has lots of stern lift and should let you plane at ~12 mph, has a good hole shot and very good cruise mpg but may give up 2-3 mph on top end speed to the Viper. Both the Cyclone and Rebel are very heavily cupped so act like their pitch is much higher than advertised. I can only spin the 15P Cyclone to ~5400, but that's perfect for my motor which has an optimum RPM of 5300-5500. Optimum rpm on the newer 150's is more like 5500-5750.

[kevin.ri]

I curently have a standard Aluminum prop... I ideally would like a little more stern lift as I fish new england waters when its can get sloppy quick... the better on plane at lower speed seems ideal to me, since I fish a lot of reefs where I need quick planing bouncing between spots. Im thinking the 17in pitch but at the same time wonder if I should just drop to the 15in pitch. Either would be better just have to pull the trigger. What I really want is a 23ft Seacraft to come up for sale with an outboard that I can afford to go up for sale locally. Wishful thinking.

thanks for the insight.

[fishstu]

Originally Posted by kevin.ri

I curently have a standard Aluminum prop... I ideally would like a little more stern lift as I fish new england waters when its can get sloppy quick... the better on plane at lower speed seems ideal to me, since I fish a lot of reefs where I need quick planing bouncing between spots. Im thinking the 17in pitch but at the same time wonder if I should just drop to the 15in pitch. Either would be better just have to pull the trigger. What I really want is a 23ft Seacraft to come up for sale with an outboard that I can afford to go up for sale locally. Wishful thinking.

thanks for the insight.

Hi Kevin

I fish the same waters and and probably will be fitting fitting a Etec 150 to my 2001 SC 20 MA.
I sent you a PM - not sure if it got to you ( no record of being it being sent in my records)

Can you PM me either way - I would like to chat with you about your experiences with the Etec 150.


Thanks
Stewart

[Bushwacker]

Originally Posted by kevin.ri

I curently have a standard Aluminum prop... I ideally would like a little more stern lift as I fish new england waters when its can get sloppy quick... the better on plane at lower speed seems ideal to me, since I fish a lot of reefs where I need quick planing bouncing between spots. Im thinking the 17in pitch but at the same time wonder if I should just drop to the 15in pitch. Either would be better just have to pull the trigger. What I really want is a 23ft Seacraft to come up for sale with an outboard that I can afford to go up for sale locally. Wishful thinking.

thanks for the insight.

It sounds to me like a good stern lifting 4B prop is what you want, probably a 15" pitch. (With the extra blade, prop slippage will be less, so you don't need as much pitch.) After you confirm motor height is correct, I'd contact a good prop shop to see what they recommend and how much they'd want to repitch your current 19" prop to 17", as that's a cheap way to get it dialed in. Once you get the WOT revs up to at least 5500 with the max load you plan to carry (check my sticky post on prop testing), then you can keep it for a spare, and the WOT speed/rpm info will help you pick the right size 4B prop.

For reference, Capt. Terry has tested several props on his transom-mounted 150 HO E-TEC on his 20' Seafari and got the following WOT digital rpm/GPS speed numbers (with AV plate on top of water, mounted 1.5" above keel):

4B SS PowerTech OFS4, 15x15: 5340/38 mph
4B SS BRP Cyclone, 14.5x15"P: 5280/40.8 mph
Michigan Vortex 4B Al, 14.0x18"P: 5390/38.3 mph
Merc Black Diamond 3B Al, 14.5x17"P: 5420/41.1 mph
Merc Enertia 3B SS, 14.5x17P: 5530/42.4

Terry's Seafari is heavier than your cc model and he carries about 50 gal of gas, so you should be to at least match his numbers or spin the same props a bit faster, depending on your fuel load and weight of crew and gear. Note: when running Merc props on an E-TEC, make sure you run the correct spacer or it may damage the prop shaft!

[htillman]

Installed a 14.5x15 cyclone and only saw a 100rpm (now 5200rpm) increase and at most 2 mph (39mph). Now I'm going to raise the engine to second hole from bottom. It's a150 exec on a 20'. I've tried a Rebel - terrible performance and a Viper (14 3/4 x 16)

Any other recommendations?

[Capt Terry]

Originally Posted by htillman

Installed a 14.5x15 cyclone and only saw a 100rpm (now 5200rpm) increase and at most 2 mph (39mph). Now I'm going to raise the engine to second hole from bottom. It's a150 exec on a 20'. I've tried a Rebel - terrible performance and a Viper (14 3/4 x 16)

Any other recommendations?

My ETEC 150 HO on my '76 20' Seafari is mounted on hole 4, the bottom one.
The AV plate to keel is 1.5", but hard to measure precisely on my trailer. From the top of the aluminum cap on the transom it is 2.0" to the lower portion of the engine mount. Skippertee observed my AV plate underway and said it was good. My normal watersports running is with a 17"P High Five. I think the only cavitation experienced on any of the tested props that Bushwacker mentioned was with a 3B Merc Black Dismond during a hot hole shot.

[htillman]

Thanks for the reply. That's where I'll be next. I raised it one hole and got a little over a 100 turns more and 2mph speed. I'm going to bottom hole this week and giving it another shot.