Interesting Twin Idea

[Joe Warren]

Power to weight the 67s have the upper hand, that's easy just weigh the engines and HP. as for the RR Joe its a dated design and glad to see its growing and maturing after all these years. as for weight well heavy boats seem to run well in race water and very very light (Marty) boats seem to be good for SAW unless you want to rebuild like Nascar all the time. Tested a different designed rear end yesterday on a rigger and found it worked as planed, we have been missing the boat just building the same thing that's been working for years. see ya at Brandon soon

I disagree , 80's are where its at on the power to weight deal imho , same case bearings , flywheel carb etc . Out of necessity I'm putting 90's in a boat designed for 80's , it won't be any faster but that's what i've got .

Marty , respectfully it's a waste of time , the two boat idea that is . just get both new motors running good and ride the platform for years . all good things unfortunately come to an end though .

Now Tom has touch on another Interesting Point. The Old Roadrunner 80 Twins ran a 3 inch center line shaft to shaft. Later on the 90 Xtreme twin was Built & Because of the engine spacing 2.050 the Drive line had to go to 3 1/4 center to center. If you run a 90 engine in a 90 Boat You will not experience any problems with the wider center line. However if you run 80`s on a 90 tub (3 1/4 centerline) you will prop down on cup. (meaning 80`s run best with a 3 inch center line Boat hull for max prop cup) the wider the prop center line is the less turbulent water gets throwed into the other prop making it harder to launch Big Cup Props & Run Fast..... Also the Wider the props center line is the More a Boat wants to run straight & Not Turn Well........ Now if you Glue 2 Very Modern boats (Singles) together that have a 4 inch tubs each (Most tubs are @ 4 inches today?) Your center line would be 4 inches. Not an Idea race boat for twin class ?? Todays Big Engine Demand More Fuel.. If your Going to launch early & mill 3-4 laps & Race 6 hard laps you need 20 Oz for the 91-VAC & Approx 25 oz ea for a Fuel Flowing RS101. Ralphs new 2010-2011 Nitro twin has a Wider Boom tube spread, A different Sponsons & Tube Geometry, Different & Longer sponsons, Higher sides on the tub, Really a Totally different boat than we raced just 2 years ago. Many of the improvements are to Haul More Fuel & Handle the Power of todays CMB BIG BLOCKS. Todays R/R Twin is A Totally Redesigned Boat that looks old school I will say the VAC 91 delivers more Bang for the buck than most engines. & Can be Raced pratically out of the box with no Paticular mods to do..... The CMB RS101`s delivers HUGE / MONSTER TYPE POWER... Soooooo what i am saying is... Sell the third car get a boat & Fuel & lets race......... B) B)

 

[Norm Doerr]

What about twin 21s?

 

[julianconde]

Norm I have a Twin 21 rigger run fast and turns very well ill show it to you when i go back to FL. Mike I did not say anything about racing it with 80 to 101 riggers that why I have my big Twin but i can race it with the 45 Hydros.

Julian

 

[Buckshot]

Julian,

I'd like to see some video of your twin 21. I have been thinking about building one for a while......just got too many toys right now.

Marty,

I agree with Joey’s last comments.



B

 

[julianconde]

PM sent Buck

julian

 

[julianconde]

Power to weight the 67s have the upper hand, that's easy just weigh the engines and HP. as for the RR Joe its a dated design and glad to see its growing and maturing after all these years. as for weight well heavy boats seem to run well in race water and very very light (Marty) boats seem to be good for SAW unless you want to rebuild like Nascar all the time. Tested a different designed rear end yesterday on a rigger and found it worked as planed, we have been missing the boat just building the same thing that's been working for years. see ya at Brandon soon

I disagree , 80's are where its at on the power to weight deal imho , same case bearings , flywheel carb etc . Out of necessity I'm putting 90's in a boat designed for 80's , it won't be any faster but that's what i've got .

Marty , respectfully it's a waste of time , the two boat idea that is . just get both new motors running good and ride the platform for years . all good things unfortunately come to an end though .

I have to agree with Tom i prefer the CMB 80 Hr's. Im currently running them on my 80 Twin the old tank and they are fast but im running them conservative. they still have alot more speed in them but i choose to run conservative why becsause i finish every heat.This time in brandon im going with the H667 instead of my small H48 with 6.9 pitch and going just a little bigger prop and taking the pipes from 12 " to 11 1/2 should give me all the power i need to be competative at brandon..

But Beware Tom New Extreme Bigg Block Big Bore is underway ummmm i smell more Twins lol

 

julian

 

[Joe Warren]

Power to weight the 67s have the upper hand, that's easy just weigh the engines and HP. as for the RR Joe its a dated design and glad to see its growing and maturing after all these years. as for weight well heavy boats seem to run well in race water and very very light (Marty) boats seem to be good for SAW unless you want to rebuild like Nascar all the time. Tested a different designed rear end yesterday on a rigger and found it worked as planed, we have been missing the boat just building the same thing that's been working for years. see ya at Brandon soon

I disagree , 80's are where its at on the power to weight deal imho , same case bearings , flywheel carb etc . Out of necessity I'm putting 90's in a boat designed for 80's , it won't be any faster but that's what i've got .

Marty , respectfully it's a waste of time , the two boat idea that is . just get both new motors running good and ride the platform for years . all good things unfortunately come to an end though .

I have to agree with Tom i prefer the CMB 80 Hr's. Im currently running them on my 80 Twin the old tank and they are fast but im running them conservative. they still have alot more speed in them but i choose to run conservative why becsause i finish every heat.This time in brandon im going with the H667 instead of my small H48 with 6.9 pitch and going just a little bigger prop and taking the pipes from 12 " to 11 1/2 should give me all the power i need to be competative at brandon..

But Beware Tom New Extreme Bigg Block Big Bore is underway ummmm i smell more Twins lol

 

julian

Julian You may want to move the pipe in 1/4 increments.12 is long pipe.. But as you shorten the pipe You may have to take shims out to keep the torque. a reduced set of dia H667 with a 11 3/4 pipe would be a good set up too. Your older boat is heavier So it is going to like a longer pipe to get up & going.

 

[julianconde]

Agreed with you on that i have the props already so when i get to FL im going in on the pipe and see what happens plus looking foward to the Extreme Twin ummmm ;-)

julian

 

[julianconde]

shims ???

 

[thomaselkins]

Julian

As much as your here in FL just move, as you know we live here on OJ and sunshine

 

[Joe Warren]

:angry:

Power to weight the 67s have the upper hand, that's easy just weigh the engines and HP. as for the RR Joe its a dated design and glad to see its growing and maturing after all these years. as for weight well heavy boats seem to run well in race water and very very light (Marty) boats seem to be good for SAW unless you want to rebuild like Nascar all the time. Tested a different designed rear end yesterday on a rigger and found it worked as planed, we have been missing the boat just building the same thing that's been working for years. see ya at Brandon soon

Well Thomas, There has been enough changes 2010-2011 in the RR XTREME that the rest of the Twins Look Dated to Me Now.......... :blink: So you either Stay on the Water race & learn or Get Passed by the Ones that DO........ :lol:

 

[Bob Koch]

I seriously thought about a triple 21, to meet the multiengine hydro displacement rules, but the 3 props would make the tub too wide. Anyone have ideas to make a legal boat without using big blocks?

My first thought was an inline triple, but the crank has me scratching my head. That, and all the bearings I would have to use to keep the crank volumes seperate. Maybe I could spline the cranks together on 3 seperate motors?

Marty's idea is one I'd be willing to try, 3 JAE tubs = 12 lb x 9.75" wide :huh:

could you not offset the props? 2 in front of the center that is further back?

 

[Scott Schneider]

Some of us on the DARK SIDE are doing In-Line gas twins ....