Looking for information for 572" twin turbo build

[Hipshot]

Hi ttmott, I don't think you are familiar with jet boats. In a jet boat the engine goes to maximum RPM almost instantly whether you are at idle when you hit it or you are at 3500rpm when you hit. The engine I am building will turn somewhere in the 6300-6600rpm range wide open, and it will see that a few times everytime I go to the lake/river. Normally I will be cruising at somewhere between 3200-4500rpm probably and I will have more power than I need in that range even if the turbos aren't doing much. A jet boat is a totally different deal than a prop boat or a street car. You just can't compare the two, it doesn't work. I will be running two GT-4780 turbos along with two HKS GT2 wastegates, two blow-off valves, billet throttle bodies, PT2400 intercooler, and FAST fuel injection.

[ttmott]

Hipshot, I do know something about jet boats and pumps; not to say I am an expert but I've been around the horn a couple of times. This is my NA jet boat. It is a 468 that turns an AT 9.25 SST impeller. Old tech turbocharging but the intent of the project was to take the wastegate-less turbochargers to the maximum capabilities with carbs. A challenge I wanted to do. The engine turns the big impeller right at 6200 RPM. The turbos are way over their max rated output. They are older Rajay's that have been heavily reworked. The turbine bypass has been machined and orifices installed to up the boost. Carbs are worked 660 center squirters. I have gernaded the setup several times getting every ounce of torque out of it. This is an older pic things are rearanged quite a bit now and the intercooler housing is several generations advanced. This boat hits so hard that the entire hull will leave the water; never does the pump allow the engine bang the rev limiter unless the pump aspirates air when leaving the water. When it comes up on boost at full throttle it will stick right at 6200, no supprises. Folks on the forum (BP and Unchained) have been a great help for me as well however, you need to validate what anyone says. I have three other significant turbocharged projects all of which are FI but not boats. Only one my Hemi is of significant displacement and FI; this one has the Turbonetics 62-1's. The big difference is (and it's my nature and profession) I validate these types of things using data and calculations; right or wrong. Input from everyone here is good information; good dialog.
Tom
http://www.***boat.com/image_center/...30DSC00368.JPG

[TurboNova]

Brian,
Don't know where you got it that I was recommending the 60-1 series compressors; no way, they are too small even for my Hemi. I am recommending either the 42 series Garretts or the Turbonetics 62 series in a duel setup configuration. Remember Hipshot stated he is building a recreation boat not a ski racer or drag boat (even though he has some nice parts) and was interested in some Turbonetics Super T series compressors. The Super T's will work but he will be in the Surge area of the map with possible damage to the units and the low end performance of the engine will suffer. The engine flow demand simply isn't there to stay within the higher compressor efficiencies of the map except for at the upper RPM limits. Cylinder heads and their flow characteristics are not as pronounced with forced induced engines; with that said, however, every little bit helps and the Profiler's will definately be better that stock oval port, for example. Also the A/R is a very nebulous term that there is little info to base sizing on; This value is based on low numbers= fast spool up but high exhaust restrictions at high RPM's and high numbers = slow spool up but low exhaust restrictions at high RPM's. Current thinking for large displacement engines (572 for example) that an A/R of .89 to 1.00 per turbine is adequate street or recreational use. Engines that live above 6000 RPM need bigger A/R's; Based on Hipshot's intro I don't think he is building something that he will keep at 6000 RPM.
So, with that said I'll continue to "crunch numbers" with streetable (boatable) success.
Tom
Believe me, Hipshot is looking for something with lots of power, I have talked with him on the phone. If you are going to build a street/weekend boating engine there is no reason to put a "Profiler" or "Big Cheif" head on it if you are looking for a little amount of horsepower. The only reason to use something like that is if you are looking at the 1000+ horsepower range. At that kind of power it becomes more of a drag race engine and less of a weekend boating engine. I just talked to a tuner friend of mine and he said they put together a 632ci big block with twin 101mm turbos 1.0 A/R and maxed out the engine dyno. He has also done a few of the 80mm and 88mm turbos like the GT47. All three of these setups went in offshore boats. A GT42 is borderline too small, yes it would work if you don't push it. Our boat is very clean and nice job on the install but we don't agree on turbo size. Your job? Some kind of engineer? I was a civil engineer with the State of Washington, I quit to open my own shop, tuning, turbo installs and dyno tuning full time. I too can crunch numbers but I also know what works, numbers on paper are just that numbers, real world tuning is something different. For example, we do alot of chassis dyno tuning, it works great to get a real close tune but when taking the car on the street/track the tune will change some. Theory, Testing and Actual Results may vary.

[Hipshot]

Hey Brian, what's up? As soon as I get through this week and Christmas we will be ordering the rest of my parts so get your pencils out and sharpen them up! I got pistons yesterday and they are the same as the CP gold coated pistons I had but lower compression. We'll be at 8:1.1 with the new pistons, and my rods will be here sometime next week as well. Steve Schmidt made me a killer deal on a set of Oliver rods he had in-house so that is what I went with. Schmidt has my heads and is giving them a once over and doing a couple of things to them while he has them. I am getting really excited about this turbo motor build and I still haven't found a 21'Daytona or Edge Phantom that I want to buy. I am thinking about calling to see what a new Edge would run just to see if I have the dough to go that route.
Nice looking set up on your boat ttmott.

[Unchained]

TurboNova,
I didn't see the GT 47 on the www.turbobygarrett.com website.
Where did you find it?
In the catalog they went right from a GT 42 to a GT60.
From what I saw the ball bearing turbos cost 2.5 times the price of the plain bearing models. How much quicker is the spool up time for that much more cost?

[TurboNova]

TurboNova,
I didn't see the GT 47 on the www.turbobygarrett.com website.
Where did you find it?
In the catalog they went right from a GT 42 to a GT60.
From what I saw the ball bearing turbos cost 2.5 times the price of the plain bearing models. How much quicker is the spool up time for that much more cost?
This is a turbo that Precision Turbo and Engine builds. There is a GT45 and GT55 also available. You are right, the ball bearing turbos do cost alot more, the spool up time is usually quite a bit quicker. I think 2.5 times is more than what they cost in my catalog. Usually the ball bearing upgrade is around $800 more but sometimes less. I know some of the import stuff that we have tuned lately have had ball bearing turbos and they will spin alot faster even at idle. The GT42 that we put in the drag boat last year was ball bearing and it would see full boost at 2500 rpms. Now that was also with a set of carbs and locked out timing. We could have made it even better with EFI.

[ttmott]

Believe me, Hipshot is looking for something with lots of power, I have talked with him on the phone. If you are going to build a street/weekend boating engine there is no reason to put a "Profiler" or "Big Cheif" head on it if you are looking for a little amount of horsepower. The only reason to use something like that is if you are looking at the 1000+ horsepower range. At that kind of power it becomes more of a drag race engine and less of a weekend boating engine. I just talked to a tuner friend of mine and he said they put together a 632ci big block with twin 101mm turbos 1.0 A/R and maxed out the engine dyno. He has also done a few of the 80mm and 88mm turbos like the GT47. All three of these setups went in offshore boats. A GT42 is borderline too small, yes it would work if you don't push it. Our boat is very clean and nice job on the install but we don't agree on turbo size. Your job? Some kind of engineer? I was a civil engineer with the State of Washington, I quit to open my own shop, tuning, turbo installs and dyno tuning full time. I too can crunch numbers but I also know what works, numbers on paper are just that numbers, real world tuning is something different. For example, we do alot of chassis dyno tuning, it works great to get a real close tune but when taking the car on the street/track the tune will change some. Theory, Testing and Actual Results may vary.
Yea I'm a Mech. Engineer working proplusion systems in the aerospace ind. at KSC. Mainly I work in cryogenic propellants and vehicle systems including engine turbomachinery and propellant transfer. Hence my dependency on numbers and testing. Your last sentence says it all but it all starts as a baseline with the numbers......

[MikeF]

Tmott, So what you're really saying is that you can design and make an impeller to move more fluid as efficiently as possible(for the jetboaters....of course)! :rollside:

[Tunnel 23]

I just brought this beast home.

[Marlin455]

Tunnel- Can you post some more pics of that 70's turbo setup?
Thanks, Stan