Fastest Vee Bottom

[propmanjay]

DBR are making some big power out of the 3L 300x but far from green. Wish I had the $ so I could play instead of dreaming. A DBR 300x on 21' Eliminator was running in the 120s at the Parker 300 until it blew over. I'm sure an Ally would run that with some skill.

 

[Lotus 50]

The SnF debate was/is about direct injected motors. I don't doubt an EFI motor would have more potential.

The Triad and SRVs are different hulls. I have heard there were only 6 of the original SRVs. RBT brought it back. His was Gray (sold), there was a yellow one, a black hull, and the 114 mph white boat. RBT may know of more. The white one went 104 with a carbed 2.5.

Fastest hull with low HP doesn't have to be the fastest with big power.

 

[xb03fs]

1.62 gears +7000 rpm 300xs plus smaller more efficient prop advantage mercury.

I'll take one if they are being given away

 

[whipper]

1.62 gears +7000 rpm 300xs plus smaller more efficient prop advantage mercury.

I'll take one if they are being given away

Yep Ill take one two. Yes even with 1.62 at only 6100 rpm its going to take a special 36 pitch prop to reach 120 without more revs. With 7000 rpm it could be done with a 31 or 32 pitch prop. Thats more like it!! Probably dont even need more HP than stock. Just enough to turn a 32 to 7000. On an Allison you probably wouldn't need more HP than 330 its the torque that needs to be sustained to pull the wheel to the 7000 range.:beer:

 

[Darth VMAX]

Ok, green motors

Unless I read the DBR chart wrong, the mod 300xs HP and torque fall off pretty drastically after 6200. Does 7000 get you much except more fuel burn? Not sure what advantage that brings over the Yamaha.

Wayne has told me the HP and torque is still holding peak at 6150 but again, I don't know if he has them able to go higher or not. Its an interesting debate on top of the v-hull debate and would really enjoy seeing a head to head.

The Torque and HP will go to the Yammie and Revs to the Merc. But not sure if those extra R's do much if the HP/torque fall off.

 

[whipper]

Ok, green motors

Unless I read the DBR chart wrong, the mod 300xs HP and torque fall off pretty drastically after 6200. Does 7000 get you much except more fuel burn? Not sure what advantage that brings over the Yamaha.

Wayne has told me the HP and torque is still holding peak at 6150 but again, I don't know if he has them able to go higher or not. Its an interesting debate on top of the v-hull debate and would really enjoy seeing a head to head.

The Torque and HP will go to the Yammie and Revs to the Merc. But not sure if those extra R's do much if the HP/torque fall off.

Yep all of the above. That motor you posted for sale is the ticket!! Wayne has done some real nice work over the years and Im a big fan of his expertise. That motor for 15500 is the same price as a 300xs only way more motor. All the goodies to get er done!. Is anyone working on the new etechs yet. My guess is they will make torque easier past the stock limiter than the XS? Those guys on the S&F thread are turning the 34+ wheels. Thats not really an option on a light hull especially a 36 pitch.:shock: My guess is even just past 100 it would be very hard to control the rotation out back. It would crab so bad the cast from the deadlies catch would hear about it.:laughing

 

[Darth VMAX]

My guess is even just past 100 it would be very hard to control the rotation out back. It would crab so bad the cast from the deadlies catch would hear about it.:laughing

Good point.

I have a solution. My TRP lower-unit. Wayne just needs to figure out how to replace the 2.0 gear ratio with 1.62's and someone needs to custom build some 34" counter rotating props for it! Whew! I think it would be easier just to mount twins LOL At least there would be no crabbing and the deadliest catch boys can stay in Alaska!

 

[Kcraft]

Hey Allison Owners & Fans, I come in peace:blah blah blah LoL

Great read so far

 

[Darth VMAX]

What the.......... (?!?)

 

[whipper]

Holly mosses wheelie any one.:big grin
Hey craft and RBT your dialing in those big bad motors on 21fters and thats awsome. Im a big fan of what your doing. Theres no doubt this the start of a new era in our type of speed thrills. Its no different than when the 2.5 first came out. Guys like you were seeing what can be done safely and what props and mods work best. What you guys are doing will help a lot of others in setting up there boats to run proper. I have the ut most respect for anyone who is trying to maximise there setup. It takes alot of thought and time to do it right and safely. The coment out of respect to you and the other guys running the big greenys about an Allison strapping on some power and claiming the crown was to get the thread going. I know and we all do that our fastest hulls dont like the weight out back. But there are other options that need to be explored. Theres a setup on an Allison that surly will surprise alot of boaters. Thats just what Allisons do. In the mean time there's no disputing the SRV,s speed capability with big power regardless of weight. Keep up the good work!
So whats on the drawing board for setup and power lately for your setup? What mods and motor do you feel will make your SRV reach the elusive 120 mph mark?

 

[RBT]

To be clear, I have no part in what he has done. It is all him, credit where credit is due. I still have my money on xr2002 or a 2001 with a 200xs

 

[whipper]

Me two.:beer:

 

[Kcraft]

So whats on the drawing board for setup and power lately for your setup? What mods and motor do you feel will make your SRV reach the elusive 120 mph mark?

A ported 300X powerhead that I don't have LoL :very happy
But I think the DBR 300xs will come close, with a little more work :wink, a race hatch for some areo and if I have too, centre steer her to get a little better balance

 

[whipper]

A ported 300X powerhead that I don't have LoL :very happy
But I think the DBR 300xs will come close, with a little more work :wink, a race hatch for some areo and if I have too, centre steer her to get a little better balance

 

[Kcraft]

To be clear, I have no part in what he has done. It is all him, credit where credit is due. I still have my money on xr2002 or a 2001 with a 200xs

Thanks RBT but you and John Speith can take the credit for building the SRV's up here...:big grin …Smart money and my money is on the Allison's as well…
Maybe RBT can elaborate a little more about the aero stuff that Boris used…:cool

 

[RBT]

I want that boat!

 

[Dave Hensley]

Dang.... That rear fairing was a tall boy. Were the through transom ducts for stability or the result of finding some high pressure areas around the inlets?

 

[RBT]

Too bad that Owen is gone, but I seem to recall that Owen said 3 mph and easier to drive. It helped with the swirling air in the cockpit and from behind the motor. If you see any runs of it running it has no water swirling behind the motor.

 

[whipper]

That is a very ingenious idea. Probably would have help that problem the 3lts had for ingesting water from the back of the cowl also.:beer: Porsche has used similar ducting for some of there race cars also in the past. As aerodynamic as Allisons are for the more passenger oriented boats running past there design limits one needs to think outside the box for sure. Those XR,s sure have a flat pad compared to my GS,s stock pad. What did those hulls weigh,sub 800?

 

[RBT]

I would say that boat is 600 ish. There are lots lighter than that