300xs on a Grand Sport Darris said NO!

[micker54]

Good Morning,

I have a friend with an Allison GS. He has a merc.280 on it . Unfortunately, %$#&*% , He put a connecting rod through the block last week.

He would like to know if anyone out there has any experience with an Optimax 300 on the GS. He is worried about the extra weight and lower RPM's. He wonders how it would affect his performance compared to the 280. He takes a lot of River trips and is looking for something to get him there and back at a high rate of speed. Is it a more reliable engine??

Any help or advise will be appreciated. I'll pass it on !!

PS. He talked with Darris. Darris told him it would be a mistake. ( to heavy )
Darris is the guru, but he was the last to come around on the power
seering thing too. Will the GS handle the weight???

 

[RedAllison]

Darris is NEVER going to promote 3.0s on 02s and 03. That being said, can the hull handle it? Yep. Will it be a different animal? Yep. Will the setup require change? MOST definately.

BUT from a safety point of view, make sure he knows about the "recall" on certain year GS boats:

http://forum.allisonowners.com/showthread.php?t=1976

That would be a REAL concern and "must do" were I hangin da biggest merky onda menu!!!
RA

 

[Tray Archer]

I have seen 250 xs on a grand sport in a pict dont ko=noe about set up but they weigh about the same so why not.......you may have to put some weight in the bow for set up reasons.
Tray

 

[K.Kiser]

I would do the transom stud upgrade for sure, and maybe go to about a 6"-7" jackplate to equilize the fore/aft balance of the rig...

 

[whipper]

rc211v AKA Greg from around my neck of the woods had a 300 on his GS and loved her with the 300X. She would do 110 in a hurry!!!!!! He talked about her on hear a month or so ago and I posted some pics with him and a bigger buddy on board and she never looked to low even with the two heavy weights on board. From what I understand she is still running strong. he sold her for a 1300hp HTM!!:gasp :big grin . He will most likely chime in hear soon as he checks out the board once and a while. Im not sure what his set back was and all. Ill look threw my posts tomorrow and see if I can find it. Its late just drove 800miles today with some new wheelsbanghead James

 

[TBuck2003]

Stick with the 2.5 the 300x is too much motor for that combo not because of the power but the torque and weight.Running a 32p wheel or higher at 6500-7000 revs is a lot different than 26-28p at 8000-8500 with a 2.5.Not saying it couldnt be done but would require all sorts of set up changes and bottom work.I would not base my decision off of one person that says its fine and went 110 mph(James not you you were just stating what you heard) Have logged many an hour in a GSE and at any speed over 103-106 the boat simply pushes a poor hole thru the air and gets QUIRKY.At 110 mph with that weight and torque it would almost be a certain nightmare.Not calling anyone out and everything is possible but like I said I have been thru the 90-95 mph range,95-100 range,and now 105plus range,and it is not safe period in that boat.Bottom line would highly recommend sticking with the 2.5.My .02

Todd

 

[badbait]

Todd is absolutely right when he says (Not saying it couldn’t be done but would require all sorts of set up changes and bottom work.) I have done it and can attest to that statement. Mine drives very well and is as fast as it was when I had a 280 on it but it was not a bolt on and go by any means. I don’t think there are any shortcuts. The motor can’t have more than 3” of setback and forget having a hydraulic jack plate. Even with 3” of setback the holeshot was not good until I came up with a ride plate that looks a little like what Darris put on the 21s. My plate is achored to the manual jackplate instead of being screwed to the bottom of the boat. The boat will now keep up with the 280s out of the hole even when their running 24 drags and have 8200 limiters. Todd mentioned bottom work. Yes you loose all your bow lift when you bring the motor into 3” and you have to get that back with some bottom work.
I love the motor It will run 100 on top and stay on plain at 16mph on the bottom end. Uses a lot less gas than my 280 did. Does not smoke and will idle all day like a sewing machine. I recently fished for two days with a couple of guys that had a Bullet and a Stroker and both ran 300X motors I asked one of them how much gas he had used for the two days and he estimated he had used 40 gallons. When I filled mine up it took 19 gallons.

 

[whipper]

 

[whipper]

I found the link if anyone is interested in what Greg had to say about his 300 GS. http://forum.allisonowners.com/showthread.php?t=3342

 

[2fast4mom]

Darris Allison phoned me and amongst other things, the topic of the 3-liter motors on 20-ft hulls came up.

In the most emphatic way possible, Darris is completely against the use of these motors on 20-ft hulls (2002, 2003, GS). He told me several horror stories and I will leave it at that, except to say that if you get into trouble at high speed with a 3 liter hanging on the back, some of the features of the Allison hulls that can keep you in a bat-turn instead of an over-and-over barrel roll, are largely negated. At best, you are going to get wet. At worst...:cuss

It is a matter of weight distribution and center of gravity.

Having said that, can it be done? YES!! Badbait and others have done it but these gentlemen have spent a LOT of time testing, re-testing, tweaking and tuning the set-up. It's not a "drop-on-and-go" matter.

Personally I will never do it. When the man who designed the boats tells me with such adamant objection to a particular thing, I'm inclined to listen to that. He told me he was even considering pulling the 20-foot boats from the market if the use of 3 liter motors on the back of them "caught on". That's a statement in itself.

Now everybody can get on here and tell me how full of crap I am, I don't care. :beating dead horse

 

[GotMyAlly]

He told me he was even considering pulling the 20-foot boats from the market if the use of 3 liter motors on the back of them "caught on".

I would sure hate to see that happen.....but you are definitely going to see more and more 3.0L motors on the 20 footers. There ain't much left for power options if you are buying new....

 

[ALLISONMAN]

i with ya lou lou!!!! a far more research has been done on allison boats than most anyone realizes and more time has been spent on other "hidden" features than just going down the lake fast!!!!

 

[TBuck2003]

OK let me be the first LOU YOU ARE FULL OF CRAP!!!!!! Lol .

Todd

 

[whipper]

I agree also. I just was pointing out a set up that worked for someone and cant emagine what that beast would be like to drive! Im sure it would be a blast but like you said lou what about saftey. At 94 in my GS any little wisp of air or over correction and she feels on the edge at 100+ I cant emagine in our light vee hulls. The intended use of the boat is a major factor in power choice I believe. Personally the lighter the better! I would look for a new rebuilt 2.5L before I spent money on a new 3L anyday! Its the power to wieght ratio that helps with performance. These boats were designed to have a 2.5 on the transom not a 3L. Im sure theres arguments on both sides of this but bottom line is if the man maken them says no way then as lou pointed out one should listen! If the builder of STV says dont put a paticular motor on this hull because you increase your chances signifigantly of blowing over what would you do. James

 

[RedAllison]

Just because it planes off and runs 90-100+ doesn't mean it's working properly! Call Darris and ask him (just be sure you're schedule is free for the next couple of hours! :laughing ) he'll explain the whole "pushing the azzend down, having to over trim to get the nose up etc etc...". The possibility of a barrel roll and having to cut the bottom to make it work is reason enough I said, "Screw dat"! I don't know whether or not anyone heard or remembers, but "OZ" (Ricky) got chunked OUT of Lundys 03/300HPDI at this years rally! Previously about the only way to get slung outta 03 with a smallblock was if you had the motor jacked much above 1/2"-3/4"+...

Since Todd tabled it, I'll second the motion... LOU IS FULLA BOOSHEUT!!! :big grin :razz
RA

ps
And DURN RIGHT Lou AINT puttin no big blocks on his 20'ers, da man got a dozen 2.5s and Drags to go through first!!! lmao

 

[ally2dextreme]

lets see 2.5 400lbs hydrojack plate 89= 489lbs 300x 497lbs 4inch jack plate 30 lbs=527 move battss from back= doable. did i ever tell you about the stry of me telling darris hydro sterring was not the devil.lol times they are a change -n

 

[Darth VMAX]

Thanks for the post Lou. I would love for the man himself to post his thoughts and reasons on this. I find this very interesting and reassuring as to my decision to go with the 2.6L Yamaha instead of the 3.1L on my 02.

 

[mikesufka]

Just curious, but what's a 1992ish ProV 200 Yamaha weigh, as compared to a 2.5 EFI or 280 Merc?

Mike Sufka
St. Cloud, MN

 

[badbait]

Now this is starting to get interesting. I’m not an engineer but I don’t think it takes one to figure out which motor is putting more stress and has more leverage on the transom of a XB2003. Is it a 400 pound 2.5 at 14.5" of setback or is it a 510 pound 3-liter at 3” of setback. I have a single axle trailer and with the 280 on the boat at 14.5 inches of setback (which has the blessings of all the right people) my tongue weight was 60 pounds. With the 3-liter on the same boat at 3” of setback my tongue is 234 pounds. I don’t think it takes an engineer to figure out which setup is putting the most stress on the transom and has the most leverage to raise the bow. Are there any engineers in the house that could actually calculate this. I think you engineers will find out that you have to bring your 2.5 into 8" to equal mine at 3".

 

[Darth VMAX]

Mike,

According to Yamaha the 2.6L 200 ProV/VMAX Carb motors weigh 415 lbs (thats probably not a user weight, prop, fluids etc.). I think the biggest (heaviest) motors Darris will "bless" on his 20' boats are the small-block Yamaha Vmax HPDI's and they are pretty stout listed at 468 lbs (this came from a dealer not Darris himself). I think the Mercs are next at 450 lbs and the ETEC's are 419. Don't know what some of the smaller 4-strokes weigh (except I think the 4 cyl Verados are 510 lbs).