DFI or 4strk, best torque & acceleration

[billybob]

Am I wrong. All the 3.0litre Mercury OPTIMAX, Have more torque & acceleration than any of the newer 4strk's in the same size HP rating. Anyone have comparisons of the same boat with new 4strk. power. THANKS.

[Glastron1987]

Good question. Hope somebody can answer it. I've never heard anything negative about the "new" four-strokes. Can that be possible?

[David]

I think the 300R is faster and has better acceleration. That’s been discussed a bunch on the main board here.

[skialot2]

From what I have heard, it's not a one size fits all answer. The four strokes have the torque advantage. But on the small lightweight boats the 2 strokes are faster. But on the bigger heavier boats the fourstrokes are faster. Setup is also a huge factor. Setups that work great on a 2 stroke works like **** on a fout stroke. And vice versa.

[David - WI]

I think the 300R is faster and has better acceleration. That’s been discussed a bunch on the main board here.

A 300R is 4.6L versus 3.2L for the 300XS Opti. Liter per liter (or dollar for dollar, or pound to pound) the 4-jokes aren't even close... a 4.6L Opti would easily be up 100hp on the 300R. (Plus cheaper, lighter, probably cleaner, etc.)

[JPEROG]

I have not seen an instance where a (properly set up) 300R gets out run by any other 300 two stroke or 4 stroke unless they were modified or in a short drag spurt. We are discovering that you can really make a 300R run with some added compression and head work.

Joe

[David - WI]

Still, a "modern" two-stroke of the same displacement built using state-of-the-art design and manufacturing would humiliate them.

Example: all the modern 2-stroke kart & motorcycle engines use a different style bearing cage with a dramtically better lifespan. Modern = increased durability.

Example: CNC porting noticeably improves tuneabily and output; along with durability.

Example: modern engine management systems adjust fuel & timing on individual cylinders... increasing output and reliability.

I just keep taking my vitamins and hoping I live long enough to see the next two-stroke Renaissance!

[JPEROG]

Still, a "modern" two-stroke of the same displacement built using state-of-the-art design and manufacturing would humiliate them.

Example: all the modern 2-stroke kart & motorcycle engines use a different style bearing cage with a dramtically better lifespan. Modern = increased durability.

Example: CNC porting noticeably improves tuneabily and output; along with durability.

Example: modern engine management systems adjust fuel & timing on individual cylinders... increasing output and reliability.

I just keep taking my vitamins and hoping I live long enough to see the next two-stroke Renaissance!

There aren't enough vitamins; who is going to jump into the marine performance market against Mercury and then try to incorporate 2 emission requirements into their product line? 2 stroke performance outboards have sailed into the sunset unless you are at the drag races, Champ boat races, or vintage races. We ran over 80 miles today at a cruise of 90 to 115. These things just roll along at 5700 providing 111 mph on the dash. Fuel is a non-issue with low consumption and 87 octane available everywhere along our path on the St. Johns river between DeLand and Jacksonville.



Joe

[David - WI]

I'm guessing it will be Mercury... the tide will turn back at some point; it has (to a limited extent) in snowmobiles, dirt bikes, and ATVs. Once you get past the "hype" people realize that four-strokes are not inherently cleaner, cheaper, lighter, more powerful, or more reliable than two-strokes built with equivalent technology.

Maybe not until the next economic downturn... but the worm will probably turn again.

[powerabout]

how to put a 4stroke in a drag class?

[David - WI]

Also, 1970's era RAVE-style variable exhaust ports would add another 100hp to the top end and 50 lb-ft to the bottom end.

All it would take to shift the product line back toward 2-strokes is a couple retirements and the right replacements... maybe a former Polaris or Bombardier exec gets hired to a key position?

Maybe a couple board members at Brunswick age out and are replaced by a snowmobiler and a dirt bike rider who see through the 4-stroke hype?

[CRH1]

The RAVE system was proposed on the initial launch of the 3.4L 300 motor but never made it to production. To my knowledge, the only motor that had the RAVE system was the 3 cylinder 115-150 just before BRP pulled the plug on Evinrude. It would be nice to know why this system never made it to production, on-paper seemed a good option.

[wettek]

There aren't enough vitamins; who is going to jump into the marine performance market against Mercury and then try to incorporate 2 emission requirements into their product line? 2 stroke performance outboards have sailed into the sunset unless you are at the drag races, Champ boat races, or vintage races. We ran over 80 miles today at a cruise of 90 to 115. These things just roll along at 5700 providing 111 mph on the dash. Fuel is a non-issue with low consumption and 87 octane available everywhere along our path on the St. Johns river between DeLand and Jacksonville.



Joe

They might work great for big boats like yours, but for us small (16'-21' ft) guys that don't want a huge, heavy apartment block hanging off the back, bring back the 2-strokes. Just as clean, just as fuel efficient, but most importantly, smaller and lighter.

[powerabout]

There is some great data on Wildmans threads he has rigged them all new on same boats

[Glastron1987]

That would be great to see efficient 2-strokes, but I hope without adding too many parts and complications for things to go wrong.