Cybermerc150
Member
I heard a gt20 cant run over 100mph
Whats everyones thoughts?
Whats everyones thoughts?
Is an Allison GT-20 capable of 100mph?
- Thread starter Cybermerc150
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Cybermerc150
Member
The owner who had my gt20 originally ran 96mph with a promax in the early 2000s
Cybermerc150
Member
I have a ported 260 block im building carb...so ill have a ported 245 on mine
Im goaling to run 100mph with it
My gt20 weighed 1383lbs before i had to do a deck repair...and im setting it up lighter than previous owner had it
Im goaling to run 100mph with it
My gt20 weighed 1383lbs before i had to do a deck repair...and im setting it up lighter than previous owner had it
Cybermerc150
Member
Thank you sir
I had an original goal of 95mph until some said i couldnt do it in the gt20...so i upped my power, and im gonna get a lot of seat time and setup in and shoot for the BUCK!
I had a fuel restriction preventing me from turning anymore rpms on the 101mph run. I was running a 26p pro et also not an ideal topend prop. I’ve got a 30p coming and have fixed my fuel issue. I don’t personally know of anyone that has run a gt20 over 100mph.
chad202
Well-Known Member
Little advise. Shoot for 105 first. That boat requires different ballast the faster you go, every few mph takes different ballast, at least the ones I've setup did.
Freebird
Active Member
I'm guessing I may be the guy (or at least one of them) who said the GT20 will not run 100MPH. It's not about weight or horsepower, it's about aerodynamics. I was talking to Glenn Reynolds a year or so ago about this after drooling over a super nice 260 he has on his showroom floor. I talked about how it sure would look good on my GT20 but was probably more motor than it could use. That's when I asked him if he had ever heard of a GT20 (or an R for that matter) breaking into triple digits. The answer was, "no".
He told me that even Joe Burgess couldn't run 100 in a twin set-up because it just had too much lift. Said it would blow over if he stretched it out, so he had to pedal the twins racing roundy round. That really surprised me as I was sure Joe was running 100 or better when I used to watch him back in the day. That being said, I don't know if anybody has ever tried putting a lip on the pad or try any other mods to keep it more level. The bow on those boats is big and broad, and they catch a lot of air.
My advice to you is, BE CAREFUL and be prepared to get wet. You may be the first to break 100 in one, but I'd hate to see you die trying. May want to talk to Darris and see what he says.
He told me that even Joe Burgess couldn't run 100 in a twin set-up because it just had too much lift. Said it would blow over if he stretched it out, so he had to pedal the twins racing roundy round. That really surprised me as I was sure Joe was running 100 or better when I used to watch him back in the day. That being said, I don't know if anybody has ever tried putting a lip on the pad or try any other mods to keep it more level. The bow on those boats is big and broad, and they catch a lot of air.
My advice to you is, BE CAREFUL and be prepared to get wet. You may be the first to break 100 in one, but I'd hate to see you die trying. May want to talk to Darris and see what he says.
RedAllison
Well-Known Member
Be damned careful, the 20 was designed when power, gearcases and props were WAY behind the curve compared to what we have today! (And Darris was at the forefront of the development of all that as well.) Just because it runs "safely" at 95 doesn't mean it'll safely run 100! I know for a fact that more than one A-boaters have been KILLED running big numbers in the rare R-18 which was the predecessor of the 20. In fact I still have an 18 sitting in my tractor shed awaiting restoration. I used to have plans of some sort of massaged 2.5 based powerhead on it but as the guys blew them over and killed themselves in them, I said F' that and will likely find a mint tower of power or an ol 2.0 at the absolute most. The 20 wasn't designed to run the kinds of numbers you are trying to do. You'd be MUCH safer to try such in any of the XB, XR, SS 20ftrs.
Like Chad said, the 03 likewise becomes a different animal north of 100. Back in the day, Jerry Jaco told me "the wall" for the XB03 was 113! Now I have NO idea if he actually got one going that fast, if anyone could it would've been him and his guys back then. (And I'd like to see the motor they used, WOW whatta BEAST that had to have been!) He said the same thing many others that have tried have said, that console has it's limit and acts as a BIG wing pushing the nose down. The faster you go the harder it pushes down, the more you bump the trim the faster it goes, the more that nose pushes down, bump trim, go faster... UNTIL she lets go, then you are just along for the ride!!! Freebird likewise gave great advice, if Glenn Reynolds tells you something then you'll do yourself a great service by LISTENING to him. He's been there, done that about better and more times than anyone else in "Allisondom"...
Good luck and keep the wetside down!
Contractor
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...... No
SLOmofo
Well-Known Member
Why, tell me so I can agree.
Contractor
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.... In my Unprofessional opinion. Can't knock a Hole In That Density Altitude . 
allimax
Active Member
.......and as I recall that goal of busting 100 was when you were sporting a 225X, think you managed 96.3 if I recall right. Kinda like cheating with what’s hanging back there now ain’t it Jared?