Four stroke sport jet

Bluwrt · 09-12-2002, 03:09 PM

With all the talk about sport jets, some good some bad. They bad seems to be that they burn oil and alot of fuel because they're two stroke power heads.
Well with 200 and I think 250hp four stroke outboards, Why haven't they brought out a four stroke sport jet? And why is Mercury the only one making them. Do they have a patent on them?

Drachir · 09-12-2002, 03:19 PM

Sport Jets are notorious for poor fuel economy. I have a friend with a 19' NR w/ 175 S.Jet. It was suggested that we adjust the trim plate, to raise the bow a little, so we did. WOW, what a difference!! :grin: We fished three days @ Astoria in mid-August, and used only 17 gallons of fuel. Last year same number of days, and 25 gallons of fuel.

Some suggestions do help!!

FishinMission · 09-12-2002, 03:19 PM

I could be wrong here, but I don't think Merc is up to the bigger 200 /250 hp in the 4 strokes yet.

But driving by Clemens in Gladstone....I've seen some 225 Hondas hanging on the back of some Hewes boats.

Hmmmmm........If nothing else...that ought to hurry things along a bit for the other manufacturers.

Mark

Mark

Lured In · 09-12-2002, 03:57 PM

I am very pleased with the fuel economy I get on my 175SJ. I can usaully make 4-6 trips before I think about filling up again. (35 gal tank) That usually means I am slightly under half. My usual trip is around 45-60 (20-30 minutes each way) minutes of run time so that would put my fuel economy at somewhere around 6-8 gallons an hour.

As far as oil goes, I have a two gallon reserve tank that I usually will fill 2-3 times a year. That would be roughly every 7-8 gas tanks.

Doubletake · 09-12-2002, 04:34 PM

I checked the mileage on my Sportjet: @ 5,000 rpm it runs about 8 gal/hr less throttle better mileage tops out at 5400rpm. I'd say 6-8 is a pretty good average (19' sled). A four stroke would be nice (no oil or fumes) if the performance is there.

Doubletake

TheRogue · 09-12-2002, 05:11 PM

Nothing but good things I've heard about SJ fuel economy (in relation to other jets). I think it's because they're normally in boats that maybe you don't really need all that HP (Intruder, for one, hull design for a 80 outboard jet), which allows you turn plane nicely and run at lower RPM's

The gentleman at NR a few weeks ago was laying his bets on a Yamaha SJ, based on their 250hp 4stroke powerhead. ZOOOOOOMMMM goes the boat, and ZOOOOOOMMMM goes your paycheck as you try to pay for the boat motor!!

[ 09-12-2002, 06:12 PM: Message edited by: TheRogue ]

Thumper · 09-12-2002, 06:14 PM

I would be totally shocked if any jet consumes only 5-7 GPH. That is the economy range of some of the best IO's.

Lured In · 09-12-2002, 06:20 PM

Thumper...I can understand your sceptism, but it really does perform well. If you hammer the throttle and do the 'bass tournament' race around the river, you will not get that GPH. The only real way to know is to get a flow meter. Someday perhaps, but for now, I like it and get better performance than I could have hoped for.

On a side note, as we are talking about future generations of SJ's. I have two things I would like to see. Backward compatability (I can install a new model in my older boat) and some other performance options to add on.

I highly doubt that in another couple years I will be able to replace my Merc SJ with anything other than OEM replacement parts. Oh well, I knew that before I bought it.

Pete · 09-12-2002, 06:24 PM

Thumper, you'll have to come fish with me! I have the 175 SJ in my 20 footer ... If I run redline all day, I can get my economy down to 8 GPH, but if I stay under about 4500 RPM (which moves me about 30 MPH) I can keep economy to about 6 GPH.

I have never talked to anyone that has the SJ I/O option ... I know Alumaweld sells them. I wonder what economy is like with that.

Wright Angle · 09-12-2002, 06:50 PM

A friend of mine has a 19' North River SJ , 16 degree Vee. he just put a $200 fuel flow meter on it. He was a little surprised.

Wide open throttle (wot) 21 gph
Idling 2.5 gph

I don't remember what he told me about his cruise speed gph, but I know it wasn't near as good as he though it was.

[ 09-12-2002, 08:27 PM: Message edited by: Wright Angle ]

MX man · 09-12-2002, 06:54 PM

. I have a hard time forseing a compact 4stroke sportjet. One of the biggest reasons The 2stroke SJ is so popular is because it's an imbord that takes up half to minimal space compared to a bigblock. Although I would love to see a 4stroke application I just cant see it happening any time soon. But we can all hope!

brshooter · 09-12-2002, 07:19 PM

Drachir,
By raising the trim plate to raise the bow, what effect did it have on porpoising?

Boater,
How long can you stay quiet on this topic?

:grin: :grin: :grin:

Flatfish · 09-12-2002, 08:59 PM

I don't understand why you would pay the big bucks for a 200-225 4 cycle SJ when you could buy a big block with a 212 on it instead.The only reasons I can think of to buy a 2 stroke SJ are price,performance and size(compared to a full sized Chev or Ford).The 2 strokes gain RPMs at probably twice the rate of a big block.To me at least,acceleration at mid range speeds is much more important than absolute top speed capabilities.
As far as burning oil,yeah they do. Thats the tradeoff.But i kinda like the smell of 2 stroke exhaust.The smell of it usually means I am not the power plant for the boat today.
But then again,I buy lottery tickets so I can buy that Motion Marine with twin 240s.Or maybe a Predator with a 250 on it Now all I gotta do is pick the right numbers.
Mark and the dog.

John · 09-12-2002, 10:21 PM

Merc is coming out with a neew 225HP fourstroke. It is a joint venture with Yamaha, at least that is what I read in a recent article.

Drachir · 09-12-2002, 10:32 PM

No affect on porposing. The boat just runs great, at 4400 rpm, with the bow slightly elevated. Just the way it should be!!

WaterDog · 09-13-2002, 07:11 AM

I calc my fuel consumption at every fill up. I write the reading on the hour meter on the dash when I fill and then do the math. Best was 3.5 gal/hr @ 4000 rpm (24mph). 7 gal/hr @ 4500rpm (34mph). I usually run around at 4200 rpms. Seems to me that is pretty good economy. Believe it or not. :tongue:

Take Down · 09-13-2002, 08:30 AM

My experience with my 19' NR is very similar to Waterdog's.

TD

Herring Impaired · 09-13-2002, 09:04 AM

I have a 175 SJ on my 19' NR, and when i got it, I was told that two stroke engines are designed to run optimally at either IDLE or WIDE-OPEN. Supposedly the SJ will burn 10 GPH at WOT.

I now punch it, get it on plane and then cut it back to about 4400-4600 RPM, and cruise at about 35 MPH. I have noticed a decrease in consumption. Probably similar to Lured In's figures, maybe 5-6 GPH.

The boat uses gas, but I had a Blue Water 18' I/O boat that used about the same rate.

The Blue Water wouldn't go through 4" of water! :grin: At least very far....

boater · 09-13-2002, 03:20 PM

Quote:

Originally posted by brshooter:

Boater,
How long can you stay quiet on this topic?

:grin: :grin: :grin:

<font size="2" face="verdana,arial,helv">i was told when i rejoined to be nice, so you will not read anywhere about me bashing what i consider to be junk, have a nice day :smile:

Doubletake · 09-13-2002, 06:11 PM

LOL!!!! Thanks Boater

Wright Angle · 09-16-2002, 04:48 PM

I started thinking about all the above claims of great GPH (gallons per hour) rates with the Sports jets, after my friend had told me of his experience with his fuel flow meter on his 175 SJ. (above post) I was wondering who is right? why all the dealers had told me when I was shopping for a new boat that the 175 Sports Jet would burn 17 to 18 GPH (WOT) most all motors burn about 1 GPH for every 10 HP at WOT, and At cruise speed you should expect to burn one to two GPH less than one-half your maximum consumption rate. This is why I bought the boat with the Honda motor, dealer told me the Honda would burn 7 to 8 GPH (WOT) and something less then half of that at cruise speed. Is this all true??

So with all the information that I have collected on my own boat with the Honda 90 HP, I started doing the math to see what is really going on.

From day one I've kept track of every mile down to the foot (GPS) every gallon of fuel to the 1/10 and every hour to the 1/10 (Honda gauge hour meter) on my new boat.

My boat is one year old ( took delivery on 9-11-01

) I don't have a kicker so all the miles are attributed to the 90 HP Honda

Total Hours 68.3
Total Miles 580.55
Total Gallon of fuel 113.05

This is what it looks like when I average!

Average MPG 5.13
Average GPH 1.65

The manufacture Of my Honda tells me 7 to 8 GPH (WOT) 90HP@5500rpm, I assume that they have checked this pretty close.

My average looks pretty good, But I know it still burns 7 to 8 GPH (WOT) because Honda tells me it does.
I guess Im lucky I don't have to run it WOT....

(WOT) about 1 GPH for every 10 HP give or take, and At cruise speed I should expect to burn one to two GPH less than one-half my maximum consumption rate ,lets look at that, new motor very efficient, best numbers.
7 gph divided by 2 is 3.5 less the 2 gallons per hour is 1.5 GPH and that is what I'm getting.

[ 09-16-2002, 08:08 PM: Message edited by: Wright Angle ]