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Thread: 300r vs 300xs on same boat
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01-29-2020, 08:15 AM #16
While that’s the prevailing argument it’s far too simplistic. Let’s not forget that the 2 stroke does not take advantage of its entire displacement with every power stroke. Once the exhaust and intake ports are opened by the downward piston stroke that cylinder is no longer making power, it’s converting power to the exhaust and intake function. A 4 stroke creates power throughout its entire combustion stroke.
Mark
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01-29-2020, 09:57 AM #17
A two-stroke has no pumping losses. The dwell time @ BDC and the aprox 60* each side of it are used for cylinder filling.
The only wasted effort is the 30* between the transfer ports closing and the exhaust port closing. Other than that, each mark along the way, either up or down serves a purpose. The party's over by 90 - 100* after TDC so the exhaust port opens.
A four-stroke will open the exhaust between 88-90* ( supercharged or nitrous cam) ATDC and the lamest stock cam @ 110-120 after. Again the party's over. Yet the four stroke has to leave the exhaust valve open around the bottom, 180* up the back side ( this is where they sling the piston off the rod with no load unless it turbocharged) and a few degrees ATDC to create a vacuum during overlap.
80+180+10=270* of wasted motion.
Where they shine is the 10* BTDC IVO 180 of intake stroke and the same 45-60* off of BDC before the valve closes. 10+180+45=235* to fill the chamber as opposed to 120* for the two-stroke.
When you put a degree wheel on both of them and roll em over, you'll be surprised at how close the timing events that matter, are to each other ...
Last Sunday, the air was -950 @ Daytona 8:00 am ... say what ya want, that's at least 3-4 MPH fast compared to sea level or the 10 more @ +3500' that's coming this summer. Can't beat Mother Nature ..
https://airdensityonline.com/track-h...ay/2020-01-26/
Nice whip ... supa-star, enjoy it !
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Markus thanked for this post
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01-29-2020, 10:50 AM #18
That's all great but it's a totally academic discussion, 2 strokes are gone and they aren't coming back. I was simply commenting on the "generic" argument that 2 strokes make more power because they fire on every stroke. While that's true it's not a one to one with regard to displacement and as the two motors here illustrate, there's no replacement for displacement.......
One could wonder that if it weren't for public sentiment could the engineers at any of the companies come up with improved, lighter weight 2 strokes than what they have been able to do with the new 4 strokes? When a 300 HP 4.6L V8 4 stroke weighs 40 lbs less than a 300 HP 3.4L V6 2 stroke and both are considered "state of the art" where's the value in the 2 stroke?Last edited by mjw930; 01-29-2020 at 10:56 AM.
Mark
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01-29-2020, 11:07 AM #19Member
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F1 is considering 2 stroke engines running on synthetic fuel !
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Instigator liked this post
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01-29-2020, 06:26 PM #20
If you look , you will see my response to you was only related to your statement
(you said it twice actually) ... >
Let’s not forget that the 2 stroke does not take advantage of its entire displacement with every power stroke.
A 4 stroke creates power throughout its entire combustion stroke.,
Which as I pointed out ... is not true. And I offered you a way to find out for yourself.
<strike></strike>
One could wonder that if it weren't for public sentiment could the engineers at any of the companies come up with improved, lighter weight 2 strokes than what they have been able to do with the new 4 strokes? When a 300 HP 4.6L V8 4 stroke weighs 40 lbs less than a 300 HP 3.4L V6 2 stroke and both are considered "state of the art" where's the value in the 2 stroke?
I broke my crystal ball, so I can no longer see into the future. But I would tend to agree that the "woke world" has tossed the ring-ding's to the side. My first clue was when they disappeared for the motorcycle showrooms in the mid-seventies. Honestly, I'm surprised the outboards held out this long. Maybe they were better than many "now" give them credit for. Considering the lack of any real R+D on them. The ignition and fuel injection up to the Opti was a series of archaic hold-me-overs, until the Opti hit the showrooms, and even then, compared to what's really out there, it's a model T.
Two-strokes will always make more power than a four-stroke. By your own admission, a four-stroke has to be half again to twice as big to produce equal power.
Be it moto-cross, road-racing, or even on the outboard showroom floor. Mercury does sell a brand new 3.4L four-stroke. It produces 150 Hp. They had to push their chips in and start fresh if they were going to get the 300+HP crowd to jump ship to the four-stroke. Would you be so enthused if their new big dog turned the pump to 225 HP ... I would guess not.
I do have to laugh a little when I put things in perspective. One of Gordon's carb V-8's on pump gas makes 380 HP on the pump, all day long. The race version, lets just call it 500 ish. Where's the value in a pair of outboards that cost what a duplex in an older neighborhood is worth, and can only muster 300 HP without being force fed.
Kinda lethargic when ya think that they made 2 HP / CI in the mid-sixties with 2 valves and pushrods ..
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Markus thanked for this post
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01-29-2020, 08:59 PM #21
My opinion, I don`t care what you do to that 300R it ain`t ever gonna run with a stock 300 Drag motor in a 1/8th mile drag race where no minimum weight is required.
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Instigator liked this post
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01-29-2020, 09:52 PM #226000 RPM
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Going out 7.30 am got all the little things fixed will try 2 sets of wheels 15.25 x 35 5 bl through hubbers and 15.25 x 36 5bl hill props over hubbers will b testing with scawd the dawg brent.cant wait 2 c difference on top end from x.s 117.5 was best ever turning in . Know its faster in .but gonna try out tomorrow.IM A 2 STROKE LOVER 280.S ALL THE WAY HATED 300X.S DIDNT WORK 4 ME THESE R.S R JUST GREAT MOTORS
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01-29-2020, 10:34 PM #23
Same set back and jack plates as XS combo?
I CAN ALWAYS MAKE ANOTHER DOLLAR, BUT I CANNOT MAKE ANOTHER DAY
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01-29-2020, 10:35 PM #24
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any pics to share, would love to see the rig!
.
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01-30-2020, 03:53 AM #25
The Orbital technology created quite some excitement in the automotive industry, but no-one could make it work well enough, so they went back to four-strokes.
Here is one example:
https://apnews.com/548abcf6270aa0b4fef14f4a5f4ba565
<object id="__symantecPKIClientMessenger" data-supports-flavor-configuration="true" data-extension-version="1.0.1" style="display: none;"></object>__PRESENTMarkus' Performance Boating Links:
www.toastedmarshmallow.com/performance
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01-30-2020, 03:57 AM #26
See Chaz comments below.
In most applications, what practically limits 2 stroke power output is the temperature of the piston crown on the exhaust side.<object id="__symantecPKIClientMessenger" data-supports-flavor-configuration="true" data-extension-version="1.0.1" style="display: none;"></object>__PRESENTMarkus' Performance Boating Links:
www.toastedmarshmallow.com/performance
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01-30-2020, 08:29 AM #27
Sorry guys, I didn’t mean to turn this into an academic discussion of 2 vs. 4 stroke design but I did learn something so it’s all good.
Regardless, for whatever the reason, 2 strokes are done aside from a very small community of racers, enthusiasts and historians. This thread is a perfect example of why. Virtually every instance where the new Mercury V8’s replace the outgoing V6 2 strokes performance has increased. If you distill it down that’s what really matters to the vast majority of consumers.Mark
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JPEROG thanked for this post
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01-30-2020, 10:01 AM #28Supporting Member
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"Regardless, for whatever the reason, 2 strokes are done aside from a very small community of racers, enthusiasts and historians. This thread is a perfect example of why. Virtually every instance where the new Mercury V8’s replace the outgoing V6 2 strokes performance has increased. If you distill it down that’s what really matters to the vast majority of consumers."
The drive ability factor, convenience, no smoke, no noise, all of the torque, stronger case, higher height capability, 87 octane, the list goes on and on. Wait until these motors are out there with all of these benefits and making 400 hp and turning a higher rpm then current. The only guys that won't jump over are the same old schoolers that still think cast iron big blocks with carburetors are fast when in fact we are in an LS world. A lot of the past is cool and I love a bunch of it but its still the past and you will get just that "past" in most cases if you aren't willing to adapt. The only downside to the latest and greatest is $$ and its becoming unattainable for more and more enthusiast as things continue to evolve.
Bottom line is that we need to be thankful that this new product was created and that we are all present to watch it mature. Whether as an owner of them or spectator "this is a great time to be an enthusiast of performance outboards".
Joe
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Tango thanked for this post
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01-30-2020, 10:14 AM #29
No need to be sorry, it's an open discussion forum. Beside's the thread's title ... opens the door to a bit of "academia" seeping out ...
I certainly don't want to change plugs in my truck because I was stuck in "rush-hour" traffic, and fouled a couple. It's mindless, generic surface transportation that we all take for granted. No pumping of the pedal to keep it from spitting back. No waiting 3-4 minutes for it to warm up before dropping it in gear. Just turn the key and go. I certainly understand the boating market moving in that direction.
Just as I have an "enthusiast" car that has "antique idiosyncrasies"about it, I don't mind being part of the small segment of boaters that has to put up with minor nuances to be a bit different than the "new norm".
I have more than enough 3.0 / 3.2L stuff to last @ least my lifetime. And although I'm probably 10 years late on getting my **** in one pile. I have big-bore piston and sleeve kits. I'm on the final stages of getting rods built that will live @ 8000+ RPM and I was intrigued by seeing a MS-3 ECU sitting in a fish aquarium, that was happy to run a set of injectors and sparkplugs from underwater @ the PRI ( SEMA) show. BTW, you can tune those on the fly with a cell phone ..
Like they say, different strokes for different folks. And now you'll have to excuse me, but one of the So. American drivers backed one of the Porsche's into the fence at Sebring or Daytona last week, and crushed one of the headers.
And as my dad beat into my head .. son, go make hey while the sun shines ..
PS .. having Brent H. just walk around a boat .. is worth @ least 5 mph to the good ...
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JLanier571, Instigator liked this post
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01-30-2020, 10:37 AM #30
Well Joe, you make it painfully obvious that you have never plugged a 700 to 900 ci "ALUMINUM BIG BLOCK" into high gear .. with 2 or 3 guns on ... makes a LS look like the starter motor that should be hangin off the side of the block ..
http://donovanengines.com/donovan-en...num-big-block/
The thing I like about a drag strip is ..... the scoreboards !
No BS , well if I had this prop , if my aunt was my uncle ... pppffftttt
Nothing is ever finished. It comes down ta two things:
How hard your willing to work...
And, what you can hang on the board that counts ...
yea man , I went 220
Survey seyz ....
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