Allison GS, little more seat time today.

[200valeroyt]

I recently replaced the worn upper mounts and tried it out today, the mounts definitely improved the handling. The boat ran 88.8 @ 68-6,900 (on this tach), 225 PM, Performance Propeller 30 Drag, 1/4" over the pad. I assume im on the limiter and will be going with something larger shortly.
This Promax is pig rich at wot! The wash on the piston tops is nearly 1/3 across. Is this normal for a stock promax? I actually feel the speed increase with easing out of the throttle a touch.

[whipper]

I would try lower the prop shaft to 1/4 below the pad. i would say running above the pad your not getting max thrust with to little prop to move you. Your slip numbers are 14 and an Allison GS will normally run 6-8% 10 being high 14 no thrust prop to high or over trimmed. Judging buy your RPM with a 30 and knowing you were above the pad I would try lowing the prop shaft that will do two things. Bring down your RPM off the limiter of 6750 and reduce your slip enabling you to get the right angle of attach for max thrust = more speed.

There is no reason you shouldn't see 93 mph assuming you can get the 30 to the limiter again with the prop lowered more solo with 1/2 or less fuel. I wouldnt dare trim to those speeds were your prop shaft is now. But I would try and trim to there at 1/4 below.

Just remember if you hit the happy up button one more time and the rpm go up but your speed doesn't your at the edge of hooking and back that bump down again and come off slow and try again. At least your get bench mack speed doing this at different prop shaft heights. You need a GPS for the digital read out in 10ths of a MPH to do this the safest. That way you can see the slightest reduction in mph over the pedo and dial gage. They bounce over 65 to much for accurate readings.

Im saying all this because im pretty sure you don't need a 31 or 32 pitch prop yet until you reach the max speed that prop is capable of. Even then I wouldn't put a 32 pitch prop on a GS with a 225 anyway. I would spend that same amount on upping my limited to 7500 rpm and deep 6 the injecting oil and run a constant 40 or 50/1. I run 40/1 always because I enjoy extended runs in the high 80.s low 90,s with a 28 pitch prop. With a higher limiter you can get low 90,s with a 26 pitch prop and get there in hurry over lugging a 30 around with the stock limiter. Its night and day the difference having no rpm limiting you out. The proMax can handle 7300 all day at 40/1 mix with zero trouble. Ive been doing it with mine for 9 years on the same build with tighter heads.

[200valeroyt]

Thanks, I will give a lower prop height another try next time out. Before, with the motor flopping around, it was a hairy ride lower. However, this particular prop runs around 11% on my viper at a higher prop height. Of course, its a much lighter boat. Ill keep at it.:D

[200valeroyt]

Getting a bit more acquainted with the boat. Today it ran 94.5 with a friends 30 et copy around 6,500.

[njj502]

Running good. I've seen a best of 98.3. 28 knob cut, 1/4" above, 12" setback about 75-7600

[200valeroyt]

Good speed... I don't think ill get near that with this stock limiter, maybe close when cooler weather rolls around.

[njj502]

Ditch the limiter

[200valeroyt]

Maybe, I'm debating on whether I want to put any money into this pm or sell it and buy a 3.0.

[njj502]

Hard to beat the 2.5 combo but guys are sucsessful running a big block on the GS.

[JWTjr.]

Getting a bit more acquainted with the boat. Today it ran 94.5 with a friends 30 et copy around 6,500.

That's a good result. As Whipper noted, far better to turn more rpm with less pitch. More pitch = more torque on the engine mounts, skeg, gearcase and steering, and harder to control at speed. The best combo would be pitch in the 28-29 range with rpm ~ 7500. Less strain, easier to control, and engine not turning at life-limiting RPM levels.

[200valeroyt]

Hard to beat the 2.5 combo but guys are successful running a big block on the GS.Agree, hard to beat the combo. The lil Viper has pretty much ruined me with running anything less. The only reason I haven't already had the limiter raised and order a 12" plate is because i'm undecided on the 3.0.

[200valeroyt]

That's a good result. As Whipper noted, far better to turn more rpm with less pitch. More pitch = more torque on the engine mounts, skeg, gearcase and steering, and harder to control at speed. The best combo would be pitch in the 28-29 range with rpm ~ 7500. Less strain, easier to control, and engine not turning at life-limiting RPM levels.I totally agree

[200valeroyt]

JWTjr, what's your take on running a 3.0 with a non-ratcheting gcase on a GS? I never gave it much thought on my old Checkmate, but i've been reading it can be a problem with the hooking prone Allisons.

[baja200merk]

U can make 3.0 cases ratchet. My brothers 3.0 sporty ratchets now.

[200valeroyt]

I've read that also. What's involved with doing one and cost?

[JWTjr.]

JWTjr, what's your take on running a 3.0 with a non-ratcheting gcase on a GS? I never gave it much thought on my old Checkmate, but i've been reading it can be a problem with the hooking prone Allisons.

I would not like to run a non-ratcheting case on a boat with a known hooking tendency. As baja200merk said, modify it to make it ratchet. As for the 3L, there are a lot of them running around on XS and XB models, and as long as the setup is right (less setback and rearranged boat balance) they seem to work just fine.

[200valeroyt]

Thanks, going to look into it.

[Mr. Demeanor]

You bringing it to the St. Johns this weekend?

[200valeroyt]

Yes, that's the plan. I think Damon is riding with me Saturday, i'm thinking about bringing the Viper down Friday if I take off work.

[Mr. Demeanor]

What, Damons boat isnt done yet? :D

[200valeroyt]

I keep asking him, he does use his Scout on occasion.

[Michael J Giesler]

I would find a new 200 xs and put that on if your looking for better mpg and still do 95. Just remember 100 mph is not worth spending a lot of money for in my opinion in a gs grandsports handle a lot different at 100 compared to in the 90's the main thing is enjoy it they are great lake boats

[200valeroyt]

True. The way I look at fuel mileage is that its a boat, none of them are really great. I do enjoy the GS as is, just thinking of other options.

[njj502]

A 200xs would get you probably 8-9mpg at cruise. I've thought of going that route many times.

[syclone01]

Wonder how many yrs you would have to use a new 200xs to even get near breaking even???? Just the taxes would take a couple yrs to pay back in gas. Put a 250 xb on it like you had on checkmate and run 103-105 easily, you know you wont be happy till its faster than ur viper.
Chris, i promise to have one of the boats ready by..........

[Ziemer]

Put a 250 xb on it like you had on checkmate and run 103-105 easily...

Not unless it's heavily modified. Not to mention they are gas hogs...my modified big block Pantera got better gas mileage then one of those turds. Lol...

[200valeroyt]

Not the best mileage, no doubt, but on my 21' Pulsare I got 3.2 - 3.5 every time out and it wasn't driven easy, no doubt. Not sure id call the xb's turds, my stock xb ran 92.7 on that boat.

[njj502]

Xb's are ok but the xs (of any size) is soooooo much better.

[200valeroyt]

Id agree, they're very nice motors, way more refined and better fuel mileage..... But HP is HP, no matter how ya put it.

[syclone01]

Your xb ran almost 93 on the checkmate and I'm sure would prob have got another mph if you had left more setback on it as you lost a mph when you went to less. Wildmans 300xs on a similiar 21 checkmate ran last i saw 96-97 (might be off a bit as he's always trying new setups/props etc). I wonder if anybody has a 300xs on a GS and what does it run?? Sean, your XB prob had over a 1000hrs on it without the heads ever been taken off and still oil injected, that's way user friendly than some of the other motors. I know the XB's don't sip gas at cruise like some of the newer $14-18k dollar motors, but they still perform pretty well for such a user friendly motor. I do think the 2.5 platform is a great setup for the GS but you know you won't be happy with the little viper being faster. Wonder what the fastest GS is and what motor out of curiosity?

[njj502]

Fastest I've seen is Todd's from Hydromotive. I think it runs 108 with a 260.

[Michael J Giesler]

The fastest gs hands down I think is ziemers I think he went 107-108 that's real speed I heard another one that went 110 but no proof mine has been to 104-105 and it hit a brick wall I have tried about 30 different props same speed I remember Jeff Baker took a 260 off one and put a drag on it it went 1mph faster THESE boat are very scary 100+mph so be very careful they bit quick and hard

[200valeroyt]

Not that it really matters, but I thought I read ziemer corrected someone on that, I believe he said he ran 105?

[syclone01]

I know how they bite, i sold my ss2000 with a promax (ran 103gps) to one of my good friends who hooked it around 95-97mph with his gf riding. He sold it few weeks later! 105-108 surely is moving out, especially for such a larger, roomier boat as the GS.

[njj502]

98 is fast enough in a GS for me...

[Boomer 880]

Where in the set-up does the GS become unstable? Is it more from too much tilt, too high on the jack plate, prop selection, or a combination of all? I am thinking of a GS and wonder how much blowout/spin-out issues people have... does this happen to everyone eventually? I have been boating all my life, but the majority of my experience is with IOs on offshore boats. Looking to get a GS as a next boat, and have read a ton on the boat and the need for seat time and someone to show you how to drive.

[H20WKD]

Yep......GS's make great Lake Boats. Especially BIG Lakes.;)
http://i59.tinypic.com/24lonxz.jpg

Boomer...Welcome Aboard.

Don't get to worried...

With the proper set-up and careful seat time it shouldn't be a problem. I had no co-pilot up here to help the learning curve. But had no real problems after following Todd's, (Hydromotive Engineering), advice.

Setting prop shaft height....Twinsburg Ohio.
http://i58.tinypic.com/163pxe.jpg
Run two of Todd's props...
14 3/4'" X 26 R QIV OT
14 3/4" X 28 R QIV OT
And a 23p Trophy Plus for pull'n stuff.

12" setback on a CMC hydraulic Power Lift.
1/2" below, 1/4" above and even marked on the plate. Run even most of the time cruising, 2 up with a moderate load and at least 1/2 tank gas. Lower the plate and tuck it in when the Lake chops-up.
I just took my time and it went pretty darn well with only two major pucker's, and a few semi clinchers. It's all FUN now.

If you have any concerns give Todd a call at Hydromotive, he runs a GS and knows them inside out.

Stop by the Allison Boards, (http://forum.allisonowners.com) a lot of help there with some pretty nice people's.

Bob
:cool:

[JWTjr.]

I just bought another one. Looking forward to not hooking.

[200valeroyt]

I just bought another one. Looking forward to not hooking.Have you hooked a GS before?

[Boomer 880]

Thanks Bob. I have been to the Allison owners board and read through all the GS and SS postings I could find. It is a great help that so many Allison owners are willing to share and help others out. There are a few guys who post a ton of great information, and this will help. I did read about Todd at Hydromotive, so a trip to his shop might be in order one day.

[ZiemerSTV]

Ziemer, Jr's Grand Sport will definitely run 105++ but he has had it for over 10 years and has many hours of seat time. A very difficult boat to
drive. He makes it look very easy. Take this from his Dad. He has surprised many other fast boats.

[200valeroyt]

Ziemer, Jr's Grand Sport will definitely run 105++ but he has had it for over 10 years and has many hours of seat time. A very difficult boat to
drive. He makes it look very easy. Take this from his Dad. He has surprised many other fast boats.Im sure he has surprised many with it! Good speed

[JWTjr.]

Have you hooked a GS before?

more than a few times...

[200valeroyt]

I see

[David]

John, I thought you had an SS. Did you have a GS as well? If you've had both, what do you figure the speed difference is with the same power? Would it depend on the power? Claimed top speeds are a lot higher for the SS with big power, but with a 225, most SS and GS seem to run around the same. At least from what I've read. I've only seen one GS in my life and it was at a boat show.

[JWTjr.]

I had a GS in the early 90s. Fastest SS I've ever heard of with a 225PM was around 105. With the same engine, the GS is in the 95 range. With big power (drag or warmed up 260), the GS seems to stop at 110 (I've never heard of one going faster, no matter what power). The SS goes much faster (teens to 120+).

[Ziemer]

106 in mine...that's with a stock 260, no port work, nothing.

The reason they won't go faster??? I think mainly, it's the overall size of the bow and the big hole you're punching thru the air with it.

I've hooked mine twice at around 70, and one was the prop and the other was the gearcase... The boat will tell you pretty quick if it doesn't like something in the setup. With mine now, it's fairly easy to drive and takes minimal input at speed. But, again I've had it for almost 13 years.

Maybe mine will run a tick or 2 faster, but I think it'll take a bigger prop and maybe even giving it more setback...I'm at 8 1/2". I run a 28" Hoss, and it'll spin 8100-8200. 100-102 happen pretty fast, but it takes a little to get it to pull the last few mph. Trim gets fun at 100, as the boat naturally wants to drop the bow. It's also critical to have the boat properly balanced, or it'll never fly straight.

As for the 250XB...I had a friend with one on a 21' Checkmate (not the pulsare) and he was lucky to get 1.5 mpg. And I really don't think you'd see much improvement over the Promax. I'd be willing to bet, with the right prop and setup, you could get one to run a 100. May take a bit to get there, but I'm sure it's possible.

As for the SS/GS comparison... The Excel and GS are probably 5 or so mph different (I've seen less in a certain red/white SS. :eek: :p :D :D). The big difference is between a GS and a comp SS...The speed increases by at least 10+ in that case. :thumbsup:

With a 2.5 260 or 280 the GS is a 104-105 mph boat with the right setup. You might see another mile or 2, but that's it. I've seen claims of 107-108, but you'd have to show me. ;) Promax is 97-98... I've heard the 110 claim with a drag and 300 Promax, but have never witnessed it.

At the end of the day, they are great boats and a blast to drive. A ton of storage, very user/family friendly and ride real well for a 20' boat. No wood in them and they still build the same boat almost 25 years later since the first one came out in 1991.

[200valeroyt]

A lot of good info:thumbsup: I have no explanation as to why his only saw 1.5mpg though? I know what mine got.

[200valeroyt]

I think there's some misconceptions about the xb to some, the motor actually puts out around 275 to the prop stock. Around 280 with a simple cowl mod.

[200valeroyt]

Actually, a shade more than the 250xs, which is around 270.

[JWTjr.]

Those numbers are accurate. I have seen 260-270 from the 250xs engines we've dynoed for BWB articles. The XBs we ran were 270+.

[JWTjr.]

106 in mine...that's with a stock 260, no port work, nothing.

The reason they won't go faster??? I think mainly, it's the overall size of the bow and the big hole you're punching thru the air with it.

I've hooked mine twice at around 70, and one was the prop and the other was the gearcase... The boat will tell you pretty quick if it doesn't like something in the setup. With mine now, it's fairly easy to drive and takes minimal input at speed. But, again I've had it for almost 13 years.

Maybe mine will run a tick or 2 faster, but I think it'll take a bigger prop and maybe even giving it more setback...I'm at 8 1/2". I run a 28" Hoss, and it'll spin 8100-8200. 100-102 happen pretty fast, but it takes a little to get it to pull the last few mph. Trim gets fun at 100, as the boat naturally wants to drop the bow. It's also critical to have the boat properly balanced, or it'll never fly straight.

As for the 250XB...I had a friend with one on a 21' Checkmate (not the pulsare) and he was lucky to get 1.5 mpg. And I really don't think you'd see much improvement over the Promax. I'd be willing to bet, with the right prop and setup, you could get one to run a 100. May take a bit to get there, but I'm sure it's possible.

As for the SS/GS comparison... The Excel and GS are probably 5 or so mph different (I've seen less in a certain red/white SS. :eek: :p :D :D). The big difference is between a GS and a comp SS...The speed increases by at least 10+ in that case. :thumbsup:

With a 2.5 260 or 280 the GS is a 104-105 mph boat with the right setup. You might see another mile or 2, but that's it. I've seen claims of 107-108, but you'd have to show me. ;) Promax is 97-98... I've heard the 110 claim with a drag and 300 Promax, but have never witnessed it.

At the end of the day, they are great boats and a blast to drive. A ton of storage, very user/family friendly and ride real well for a 20' boat. No wood in them and they still build the same boat almost 25 years later since the first one came out in 1991.


Good stuff Ziemer. Very good info, I have seen pretty much the same. But, I'm not so sure about the reason for the 110 mph wall. The Triad V21, for example, will easily run 110. I had one a few years back that had nothing more than a 280SS with 260 ignition and electrical system and a Brucato PCU tuned properly. It ran 110 with no odd performance issues, even loaded with gear--wakeboard, anchor, stereo, life vests, ski pole, etc. I never even tried to get more. With a little setup and testing, I'm sure there was a few more there. Who knows with a Drag or a big-block OMC or Merc? The GS swaps ends so quickly with just the slightest wrong setup or bump to the trim, it may be that we haven't seen anything over 110 because no one wants to go there!

[Ziemer]

I think the Triad overall is just a faster boat, and size wise is somewhere between an SS and GS. It's not quite as big or deep.


Good stuff Ziemer. Very good info, I have seen pretty much the same. But, I'm not so sure about the reason for the 110 mph wall. The Triad V21, for example, will easily run 110. I had one a few years back that had nothing more than a 280SS with 260 ignition and electrical system and a Brucato PCU tuned properly. It ran 110 with no odd performance issues, even loaded with gear--wakeboard, anchor, stereo, life vests, ski pole, etc. I never even tried to get more. With a little setup and testing, I'm sure there was a few more there. Who knows with a Drag or a big-block OMC or Merc? The GS swaps ends so quickly with just the slightest wrong setup or bump to the trim, it may be that we haven't seen anything over 110 because no one wants to go there!

[JWTjr.]

It's shallower, no doubt, but the same size length x beam. And it is a faster boat--but most don't want to admit it, especially since ironically, it's been denigrated as nothing more than a R20/GT20 copy, which it is not.

[Boomer 880]

What do you guys do, when coming off a high-speed run, as it relates to engine height? I have read to never cut the throttle or bad things can happen. With that said, do you tuck the engine slowly and/or drop the jack plate while letting up on the gas?

[Ziemer]

What do you guys do, when coming off a high-speed run, as it relates to engine height? I have read to never cut the throttle or bad things can happen. With that said, do you tuck the engine slowly and/or drop the jack plate while letting up on the gas?

Whatever you do, don't do more than one thing at a time. I have a static plate so my height doesn't change. I very slowly and carefully back out of the gas and then bump the trim a little. Don't down trim and let off at the same time. One or the other.

[JWTjr.]

I bump the trim down one bit at a time. With the Triad, I could pull my foot off the gas at 110 and it would bow steer a little when the keel hit the water, but nothing dramatic. I even experimented by raising the hydraulic jack at 100+ to the point where I was running out of water pressure, and nothing violent...again, bow dropped, steered, came to a soft landing. I would not try that in a GS without some bottom changes first.

[syclone01]

106 in mine...that's with a stock 260, no port work, nothing.

The reason they won't go faster??? I think mainly, it's the overall size of the bow and the big hole you're punching thru the air with it.

I've hooked mine twice at around 70, and one was the prop and the other was the gearcase... The boat will tell you pretty quick if it doesn't like something in the setup. With mine now, it's fairly easy to drive and takes minimal input at speed. But, again I've had it for almost 13 years.

Maybe mine will run a tick or 2 faster, but I think it'll take a bigger prop and maybe even giving it more setback...I'm at 8 1/2". I run a 28" Hoss, and it'll spin 8100-8200. 100-102 happen pretty fast, but it takes a little to get it to pull the last few mph. Trim gets fun at 100, as the boat naturally wants to drop the bow. It's also critical to have the boat properly balanced, or it'll never fly straight.

As for the 250XB...I had a friend with one on a 21' Checkmate (not the pulsare) and he was lucky to get 1.5 mpg. And I really don't think you'd see much improvement over the Promax. I'd be willing to bet, with the right prop and setup, you could get one to run a 100. May take a bit to get there, but I'm sure it's possible.

As for the SS/GS comparison... The Excel and GS are probably 5 or so mph different (I've seen less in a certain red/white SS. :eek: :p :D :D). The big difference is between a GS and a comp SS...The speed increases by at least 10+ in that case. :thumbsup:

With a 2.5 260 or 280 the GS is a 104-105 mph boat with the right setup. You might see another mile or 2, but that's it. I've seen claims of 107-108, but you'd have to show me. ;) Promax is 97-98... I've heard the 110 claim with a drag and 300 Promax, but have never witnessed it.

At the end of the day, they are great boats and a blast to drive. A ton of storage, very user/family friendly and ride real well for a 20' boat. No wood in them and they still build the same boat almost 25 years later since the first one came out in 1991.

I would really like to see what Seans boat would do with the xb250 like he had on prior boat, so user friendly and puts out great power. I know most people see the "fishing motor" cowl and just think it's a turd but in reality its a 300promax with a "fishing motor cowl" and different ecu (slightly less timing than the 300PM) and richer fuel computer. A lot of the 300PM guys were blowing powerheads and they went to the 250xb fuel computer to richen it up some.The boat would have to run faster than a 225promax like he has, and that's the name of the game as far as Sean goes.

[whipper]

As much as I would like to put a 300xs on my GS I think the best all around motor for these boats is the 260 or any 2.5. Its all about power to weight. The extra weight and low rpm of the 300xs wont make it accelerate as fast. There for not as fun though fun in there own right off course. Harrells loves his with the 250xs and has no trouble into the 90,s. Put 4 in his GS and the big block still pulls hard. But a 260/280 will get you as mentioned into the low 10,s in a hurry! The 260 even quicker because its lighter. As todd and others have done even with 4 in the GS with a 260 103 mph is possible.
The highest speeds in a GS were from a guy in Alberta who boated on Skaha Lake down buy me. He had a 300 PM with Simon motor sports mods. In the neighborhood of 335 HP. He ran 110 with 4 in the boat. He said his GS ran better with people in her with that motor over solo trying to reach those speeds. I can see this being the case. As guys with 260,s will tell you the boats gets a little flighty with the big bow area over 104 at times so having the weight and setup seemed to make the GS feel more {planted}. The lip on the pad has an effect at higher speeds also. Ive done extensive pad work to mine. I have no lip on the pad. Letting off from 85 mph with mine is easier since I done this. I can turn the key off at 85 and she just settles down. Into the 90,s i can take my hands off the wheel. But that would be really dumb so only tried it once for a sec.Theres a video on Youtube were I took one hand off and adjusted my visor to show i could going 93.
Its all relative, speed. Going 90,s with a 225 is stinging her out on a thread! Its maxing out the trim and motor. Were 106 with a 260 is the same, your maxing out the trim and the motor. Your one more bump from loosing forward momentum. But a 335 hp big block back there with 7000rpm and a 32 pitch prop 118 is the theoretical speed with 1.62 gears at a conservative 10% slip. The velocity at those speeds is punching a hole that takes the shape of the hulls frontal area of a GS to whole different level. Not to mention the cock pit area. I feel a race hatch would be necessary to go past 110. The air that passes over the wind screen deflects up then down into the back seat area creating a parachute effect against the rear bench. If you stream lined that area to allow the air to pass on a deck and out the aft portion of the hull better this would help I feel. The nose and deck on the GS is well shaped to handle the velocity. On step the strakes have an ero design that progressively create lift aft and out at the transom. thats why at over 100 with a light motor the bow wants to drop. the effect of the air passing into the cockpit creates a down draft greater than the lift crated buy the hull forward of the stern. In other words they work against each other. Then theres the lip that also makes these forces amplified buy having less running surface area to control. Thats why the 335 hp promax GS could get 110 with people in the boat. The passengers displaced the down draft in the cockpit and aided in the over all down force buy off setting the pads tendency to want to drop the bow because it was deeper in the water.

Look at the fastest Allisons. They have shallower cockpit area, less wind screen effect or smaller better shaped rear bench like the SS and shorter narrower cockpit for instance. The 02 has a just a small wind deflector like a motor bike and air can pass on both sides of it and a much shallower cockpit lessing the parachute effect out the back of the cockpit. The RR stream lines speed machines like no other vee bottom. Tinny single slide your but in and go!:D
Next time your going down the lake at 90mph with a passenger in the back seat of your GS ask them how there breathing is. the air is smacking them in the face pretty hard. I remember my wife asking me to slow down because she couldn't catch her breath.
These are just my observations of trying to get every last mph out of my GS and what I would try if I had a 300XS DBR modded motor.:reddevil:

[200valeroyt]

I haven't been fast enough in the GS to really notice any bow drop, but id guess its similar to my wedged padded Viper? I'm sure in the Viper the windshield is playing some part with this also. 99% of the time it will nose down around 97-98 and run there until another bump or two with the trim. As you stated, there's also drag in the cockpit going on with these boats, ive tried more than once to run the viper without the rear seat only to lose 1-2mph and shixxx handling.

[200valeroyt]

Im not a believer in that a GS would be a slouch in the acceleration dept with a 250xb, they have plenty of torque to get a sub #1,000 hull moving.

[Ziemer]

Weight makes all the difference with acceleration. Weight and motor being equal these boats will run with any of them in a 1/4. Surprised a bunch of guys in mine. ;)

[200valeroyt]

I'm sure you have:thumbsup: nothing wrong with drag racing, ive done my share of it with cars and bikes. Thats not really a concern with me regarding boats, im just a recreational boater that's always trying to better MY last speed. Thats my race:)

[H20WKD]

:thumbsup:Acceleration is good....hence the name.;)
http://i60.tinypic.com/5l9b0p.jpg

Bob

[ZiemerSTV]

Ziemer can really drive that Allison in a 1/4 mile or top end. It is not as easy as he makes it look. I had to have an STV with training wheels
to keep up with him. Daddy "Z"

[Boomer 880]

I read about people doing an Allison-cut skeg... where on the skeg is the 'cut' and what is the theory behind this?

[whipper]

Its a swept skeg a little more cutting the leading edge back more. Or more swept back is the out come. Though most guys say now the SM can be left stock with no problem. The Allison mod for a skeg goes way back in years. I cant remember at what speed the stock SM is capable off on an Allison but theres guys that can chime in that go 110+ that would know that answer. lighter hulls and faster boat guys try many things for safety and just experimenting seeing what works and what doesn't.

[Ziemer]

On a GS, no need to do a allison cut skeg. ;)

[Michael J Giesler]

As far as mpg I can run my gs all day on 20-25 gallons of gas I even have a 280 get good mpg as long as it's not on the rev limiter I am actually pulling mine out of mouth balls in the next two weeks

[props4u2]

What do you guys do, when coming off a high-speed run, as it relates to engine height? I have read to never cut the throttle or bad things can happen. With that said, do you tuck the engine slowly and/or drop the jack plate while letting up on the gas?

There are two major mistakes people make when letting off after a high speed run.
Number one is, they a have over trimmed and chop the throttle which turns in to an instant bow steer situation. In this instance it's best to bump the trim down first then get out of the throttle.
The number two mistake is to chop the throttle and jerk the wheel to the right which is a natural reaction since the steering wheel will want to turn to the left as the torque is released from the prop. The thing to do is to actually steer to the left slightly at the same time you drop the throttle. Once the boat makes that initial move, you can steer it anywhere you want. Once you learn this move, dropping the throttle on any 20' Allison is no problem.
On a side note, the 21' bass boats are the only Allison's that I will adjust a hydroulic plate while running at high speed and it is also the only model that I will lower the jack plate as I am coming out of the throttle.

[ZiemerSTV]

I agree trim down gradually and then come off throttle gently. It works even in an STV.

[Boomer 880]

Any thoughts on running 3-blade versus 4-blade props on the GS? Is handling any different, or is it more a factor of the blade shape?

[200valeroyt]

Slight increase yesterday, ran 95 flat. As some have stated, I think a 225 could get very close to 100 in good air, more setback, higher rev limiter, etc... I have my eye out for a clean 3.0 if anyone knows of one? Could be a 250xb, 300pm or 300x. Also, this 2000 Promax will be listed soon, less than 100 hrs on Jay Smith rebuild, top pinned pistons, small shaft Sportmaster, stock ecu. Thanks

[syclone01]

Slight increase yesterday, ran 95 flat. As some have stated, I think a 225 could get very close to 100 in good air, more setback, higher rev limiter, etc... I have my eye out for a clean 3.0 if anyone knows of one? Could be a 250xb, 300pm or 300x. Also, this 2000 Promax will be listed soon, less than 100 hrs on Jay Smith rebuild, top pinned pistons, small shaft Sportmaster, stock ecu. Thanks
Sean, that's what you need, a motor that will get you triple digits every time out like your little viper. You know you will not be happy until you have that. (hard to be happy with a slower boat) I'm sure you could get your gs close to 100 with the 225 but it would have to be perfect weather, prop, setback, weight, wind, tide etc...now if that ally just drove on a string like the viper.....

[200valeroyt]

I agree. I'm getting a bit more use to the Allison. It definitely requires port side weight, I forgot to put it in yesterday and it was quite a handful! The 2 boats feel alot different, no doubt.

[Mr. Demeanor]

Sean, that's what you need, a motor that will get you triple digits every time out like your little viper. You know you will not be happy until you have that. (hard to be happy with a slower boat) I'm sure you could get your gs close to 100 with the 225 but it would have to be perfect weather, prop, setback, weight, wind, tide etc...now if that ally just drove on a string like the viper.....

He needs HP and you need to finish a boat! :D

[200valeroyt]

A lil more, just ran 96.2. I put weight back in today, around 45#. Still leaning to starboard most of the time, I weigh around 195. Needs more weight on port I guess.

[200valeroyt]

302755Last pass for today, 96.7. If I keep this motor, I believe it could run 100 in better air and more setup.

[Boomer 880]

What is the set-up? Prop, set-back, engine height? Very impressive results in a short timeframe. Good luck with it.

[200valeroyt]

30et copy, 9.5" setback, 1/4" over pad. I'm thinking another 1-2" may help.

[njj502]

You need more setback and a big limiter. I run low 90's all the time. 98.3 for me and I ran out of nuts. I think 100 is going to be tough with a stock promax.

[200valeroyt]

You may be right, I'm thinking with more setback, cooler air along with lower humidity it would be close though. It ran 96.7 in 94 degress and 84% humidity, stays muggy down here.

[Ziemer]

A lil more, just ran 96.2. I put weight back in today, around 45#. Still leaning to starboard most of the time, I weigh around 195. Needs more weight on port I guess.

Get it more forward. ;)

[200valeroyt]

Yes, I have shoved the lead all forward as far as it will go, maybe 2ft further forward. Should have a lil more leverage effect, although its only a couple feet further. Haven't tried it yet.

[njj502]

You may be right, I'm thinking with more setback, cooler air along with lower humidity it would be close though. It ran 96.7 in 94 degress and 84% humidity, stays muggy down here.

Youre damn close then. I ran my big number on a warm October day. Dry and prob 65-70 out.

[200valeroyt]

I don't have any pics of the boat running, but it feels like I have the bow up too high to get the hull to really free up. If that's what is truly happening it should run flatter with more setback and less wind drag.

[njj502]

Ding ding you win! Mine felt nose high with 8". Once I put the 12" on it freed right up. Runs flat as he'll now.

[200valeroyt]

Along with being a bit squirrelly from too much trim.

[200valeroyt]

Well, I decided that I'm going to try a Mercury 3.0 on the GS. I will have to wait a bit to find a Sportmaster for it, but should be fun!

[whipper]

300xs? Be way better with a load. i just got in from a 60mile + trip with a passenger this morning. A 300xs would have been the ticket for fuel and torque. Not to mention pulling skiers and tubes.

[200valeroyt]

A 250XB, like I had on my old Pulsare. Should do ok I'd think.

[200valeroyt]

It's going to be a bit longer before i get to try out the 250, I ordered a 1.62 SM for it, with an expected delivery around the 19th of Sept. I'm really curious to see how it runs, should be different.