Turbo sizing please help... Single vs twin
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Turbo sizing please help... Single vs twin

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    Default Turbo sizing please help... Single vs twin

    Ok guys....
    i have built a few turbo setups for cars and bikes but never a boat. I have been reading and reading and see many different things. I would like a single turbo but not sure if I need twins because of lag. Or does a jet boat spool real quick? I was told with a single I need to spray nitrous to get it out of the hole. It is a lake boat and not a all out drag boat. It will be a 500 ish big Chevy. I am doing the c&s blowthru on av gas. Boat went 84 mph with 700 hp. I am trying to go 100 to 110. My buddy has a precision pt101 with a 1.00 a/r for sale. Is that turbo completely wrong? I have made some calls but nobody seems to have much info. I can do 2 smaller twins if 100% needed, just like the single deal for some reason. Please give me some of your help if you have been through this.

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    Senior Member Hass828's Avatar
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    Quote Originally Posted by pigpenracing View Post
    Ok guys....
    i have built a few turbo setups for cars and bikes but never a boat. I have been reading and reading and see many different things. I would like a single turbo but not sure if I need twins because of lag. Or does a jet boat spool real quick? I was told with a single I need to spray nitrous to get it out of the hole. It is a lake boat and not a all out drag boat. It will be a 500 ish big Chevy. I am doing the c&s blowthru on av gas. Boat went 84 mph with 700 hp. I am trying to go 100 to 110. My buddy has a precision pt101 with a 1.00 a/r for sale. Is that turbo completely wrong? I have made some calls but nobody seems to have much info. I can do 2 smaller twins if 100% needed, just like the single deal for some reason. Please give me some of your help if you have been through this.
    With 500+ cid you will find that you will be better off with twins. Packaging reasons as well.
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    guys in the jet boat world are kindof like cavemen. (no offense cavemen) they dont really understand turbos and fuel injection and sensors and electronical mysteries... so when a small boat with a big hair dryer blows away their blown BB, they just add nitrous.

    that's why you see so many dual turbo BBs and other weird creations. they work, but only under certain parameters.

    why not build a compound dual or VVT EFI setup? best of both worlds, spray it out of the hole if you're racing it.

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    mo balls than $cents$ IMPATIENT 1's Avatar
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    Im with hass, run twins and forget about nitrous. If the turbos are sized right it wont need it. I dont

    Dare to be different, if it turns out great you can claim you planned it that way.

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    Interesting analogy there vspeed. I always thought boat guys did 2 turbos so there was less hot exhaust to deal with.
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    Quote Originally Posted by vintagespeed View Post
    guys in the jet boat world are kindof like cavemen. (no offense cavemen) they dont really understand turbos and fuel injection and sensors and electronical mysteries... so when a small boat with a big hair dryer blows away their blown BB, they just add nitrous.

    that's why you see so many dual turbo BBs and other weird creations. they work, but only under certain parameters.

    why not build a compound dual or VVT EFI setup? best of both worlds, spray it out of the hole if you're racing it.
    Im a general motors/john deere/ase mastertech i think i know alil more than the average guy about turbos and fuel injection lol caveman my ass

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    Default Turbo's

    Roger at C&S talked me into twin 76's. He sells the turbo's pretty cheap. 2 small ones is way cheaper than one big one.

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    mo balls than $cents$ IMPATIENT 1's Avatar
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    Quote Originally Posted by pigpenracing View Post
    Roger at C&S talked me into twin 76's. He sells the turbo's pretty cheap. 2 small ones is way cheaper than one big one.
    Roger will steer ya right. did ya go with name brand turbos or cheap omes?

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    Default turbo

    He just said they were custom from CRT. Didn't buy them yet, getting everything lined out right now.

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    Quote Originally Posted by pigpenracing View Post
    He just said they were custom from CRT. Didn't buy them yet, getting everything lined out right now.
    Do yourself a favor and run a good ignition system(d.i.s. or c.o.p. )so you can taylor timing to help spool.it makes a huge difference in spooltime. when fuel enrichens for boost and timing is where ive made the most strides in making mine leave out with nitrous big ci deals.

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    Quote Originally Posted by pigpenracing View Post
    I would like a single turbo but not sure if I need twins because of lag. Or does a jet boat spool real quick? I was told with a single I need to spray nitrous to get it out of the hole. My buddy has a precision pt101 with a 1.00 a/r for sale. Is that turbo completely wrong? .
    That big single turbo would do great on a small block but those can cost more than two smaller diesel turbos.
    How much can you buy it for ?
    Several of us run 2 Borg Warner S475 turbo's (75mm) on big cube big blocks and it makes for a 2000 hp package that can be a vast overkill.
    They are only around $ 625. each.
    Also with 2 turbo's the back pressure is so low that efficiency is great but boost control becomes a challenge.

    With turbo's you don't want to take everything you hear as fact.
    Only those with turbocharging experience may have anything valid to add.
    Kind of like opinions on E85 from those who never ran it.
    It's all, "I read" or "I heard"

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    mo balls than $cents$ IMPATIENT 1's Avatar
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    No boost control issues for me i can run down to 3lbs if i wanna or crank on the voodoo till its where i want.on mine each turn of the knob is a lb more and it only spikes a lb above my level.i love the lil bastards, best 25bucks ive spent. Gates are 60mm with 12lbs springs.gates dont crack open till boost level is met.
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    Quote Originally Posted by IMPATIENT 1 View Post
    Im a general motors/john deere/ase mastertech i think i know alil more than the average guy about turbos and fuel injection lol caveman my ass
    see now calm down there, i said "no offense"...

    so if we know that a pair of duals will only be 'perfect' under a given load/boost level/flow, then why is that the best choice? anytime you're outside of that sweet spot, the performance is less than perfect.

    big single VVT, why no? or dual mid-sized VVT if it makes you feel better...

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    Quote Originally Posted by vintagespeed View Post
    see now calm down there, i said "no offense"...

    so if we know that a pair of duals will only be 'perfect' under a given load/boost level/flow, then why is that the best choice? anytime you're outside of that sweet spot, the performance is less than perfect.

    big single VVT, why no? or dual mid-sized VVT if it makes you feel better...
    I dont think thats what was said. Large turbos are expensive. Depending how big you need 1250.00 doesnt buy much. For 1250.00 two bw475 will make 2000hp. As an example, a single at 2k hp are like 3000.00+
    Single turbo packages have lots of hot sibe piping. Not something most people would like in a small boat. Twins eliminate lots of pipe.
    Thats how l read it. Nothing more?

    Are you building or have you built an turbo engine?

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