sandeggo

I'm looking for some suggestions on a turbo.
My expectations:
Roughly 700 hp
E-85 blow through carb
Id like boost to come on at about 4000 rpms. Right now the motor sees 6k max.
I have been running this gen 4 5.3l for 2 boating seasons now.
It's out of an 07 yukon.
Vic jr. intake
Stock cam, springs and everything.
This winter I'm deleting the DOD and putting in a z06 cam.
I'd like to do a single turbo or twins, Doesn't really matter.
I do all my own fab including the headers in the pic.
I'll be fabbing up water jacketed exhaust for the hotside as I'm not too big of a fan of glowing headers in a boat.
This will be my first turbo setup and have been researching a lot. There is just too many variables and not enough turbo boat guys. So if you were to pick a turbo what size would it be?
I was given a pair of T04B25 turbos, but I doubt they'll work. A/R.60 compressor and A/R 1.52 turbine

9sectruck

iTrader: (9)

A single 76 will be more then enough for you hp goal. depending on budget a master power would be a good cheaper start, and a single would be less tubing cramed into the boat. less oil lines to worry about failing and catching the boat on fire. you will have to up your pitch on the prop alot to keep the boat to 6k range

pnykillerz28ls1

iTrader: (1)

Twins might actually be easier to do because it dosent look like you have much room front to back for a cross over plus twins would look alot cooler. And i get why you would want water jacketed exhaust but the cooling would make you loose alot of velocity, not that you would worry about spool time in a boat as much as you do in a car but still just my .02. I know way more about boats then i do turbos haha

sandeggo

Yeah twins look badass on a boat, I'm not too worried about the loss of velocity, the water for the exhaust is 85* and I assume will heat up quickly. About 8" away from the headers is the gas tanks. Just confined areas and don't want the glowing headers. I also know way more about boats than turbos. I'd actually like it to be laggy so I'm in boost on the top end, not necessarily while cruising. I'm going 70 now. Other similar boats are doing 100+ with bbc 700 horse. I figure that's where I wanna be

slow67

iTrader: (2)

I've always wanted to put the turbo where the scoop is, on top of the carb/intake, with the downpipe sticking straight out the back.

slow67

iTrader: (2)

Like this (only one I've seen).

a4ls2goat

**** that! I drove a boat going 45mph and it felt like I was flying. I can not imagine 100+ mph. !

sandeggo

It's very addicting. And a rush you just can't get in a car. Looks like I'll be shopping for a single this go around.
Is the 76 a t4 or t6?
What a/r ratios am I looking for?
Thanks for the suggestions
Oh and one last thing, my 700hp mark I want to hit is at the flywheel.

DavidPHumes

iTrader: (1)

A T4 flange 76mm with a .96a/r is probably a good place to look. It will easily hit 700 at the flywheel on 10-12PSI.

sandeggo

Thanks for the replies

2nd Gen Fl 'bird

iTrader: (13)

Been 92mph in a Allison and it is veeeeery addicting. After the rush I wondered what 100 would feel like. The OP's boat looks like a surf board with a V-8 hanging off of the back. Now turbo? I like.

slow67

iTrader: (2)

If your on a tight budget, the Ebay GT45 turbo seems to be reliable and cheap (should be good for 750-800 fwhp, and its got a nice big 87mm turbine with a 1.05 A/R housing), or if you want a name brand, get a BW S400 75mm turbo (good for 1050ish fwhp) in a T6 configuration (again, nice large 1.32 A/R 96mm turbine side).

sandeggo

Lol, you should see the same boat with blown alky big blocks in them. my hull weighs in at roughly 450-475lbs so it should scoot ok with a turbo.

sandeggo

Not really on a tight budget, more into reliability. I'll be using this thing every-every other weekend at the river during the six month summer. I don't want to do a max effort setup. just looking for a reliable boost system.

2nd Gen Fl 'bird

iTrader: (13)

My buddy has a similar boat as yours with a blown big block. After explaining what these 5.3's can do with a simple turbo, he's a little "ill" about comparable power numbers. He has some serious cash in his when he could've made the same for peanuts with an LS motor. We need video when the turbo goes on. Hell, I wish I was close enough for a ride when it's done! LOL

slow67

iTrader: (2)

Then I would go for an S400, they seem to be tough as nails. Hass828 is running them, and Mark55 was running them (he is up to an S480 now I think). It should spool around 3500-4000 no problem.

Also you can buy water jacketed manifolds for around $425, and you won't need the risers (you can build water jacketed hot pipes too off the manifolds if you want).

The T04B25s would likely work as twins, but not sure if you would be in boost when you are cruising (they will come in MUCH quicker than 4000 rpms).

OkieDave

I'm putting one together now. a 430 pound Cheyenne with a 76mm on3 turbo. intercooled and water/meth injected and just ordered Megasquirt for it. I know I'm at the point where I need some help and I've been on another project lately but I'm about ready to get back on it and finish it. I have a friend running a blow thru on a 5.3 in a jet boat. mild boost, 7 pounds, around 600 hp. hoping mine will eventually go to 800 or so with stock LS1.

sandeggo

The blue and white one? Is it one of the new Cheyennes? The Cheyennes are nice hulls

sandeggo

I'll probably end up building my own exhaust. I teach welding for a living so I have the right tools and know how. Thanks for the help!

sandeggo

I picked up a gt45 on eBay. Piecing together the parts to get rid of the DOD and trying to locate a stock piston. I am trying to figure out some cam specs. It's hard to judge because this is in a jetboat with no transmission. I spend most of the time past 3000 rpms. Any recommendations?
I'll be using this thread a a build thread once I start doing the hot side and buildup.