John ,

It was a pleasure talking to you this afternoon, I felt like we could talk for hours non stop. Nice to share our experiences,
By the way,as I said earlier,need to find a dyno around here,if anybody knows someone reliable, please let me know.

I am glad this is helping you, believe me, my whole set up was developed by just reading and learning from this fabulous site! And of course by a very patient builder who listened to all my requests.

Same here my friend. I will keep my ear to the ground on the Dyno...I know Tommy over at Powerboat Nation/Chief in 'Lauderdale has one and I think Cobra in North Miami has one as well. I'll make some calls next week...how close are you to a run?

John ,

Thank you,

I think by October 15th it should all be ready to go. I heard about Tommy ! Let me know If you hear something.

Hey Sprink58 ,,,, did you have any reversion problems ,, what boat are they in ,, how deep does it sit in the water

Question

Do reversion and/or water ingestion problems get resolved by closed cooling(half syst) ??


http://www.perfprotech.com/store/App...-half-flow.jpg

No problems...stock ride height...Formula 255 Liberator.

[IMG]http://i705.photobucket.com/albums/w...9/79-255-2.jpg[/IMG]

http://i705.photobucket.com/albums/w...g_edited-1.jpg

Makes no difference...the factor is the overlap between the point where the exhaust valve is still open while the intake valve is beginning to open....creating a negative pull on the exhaust system. I think any thing beyond 275* of duration w/112* lobe centers becomes a problem. If it's marginal then it can be overcome with longer risers.

Reversion happens usually when you back-down suddenly and the following wave pushes sea water into the exhaust system. It can also happen with a sudden reverse in a marina. Even though it's not performance oriented...the stock Y pipe set up with the flappers does a great job of preventing this. FYI...according to Dennis Moore in his SBC Chevy Marine book...the stock thru prop system does a superior job of exhaust scavenging at low and mid RPMs as opposed to thru hull. This is due to the negative pressure created by the prop spinning thru the water...the tipping point where the thru hull gains an advantage is beyond 4000 RPM. Interesting point to consider when dialing in a Cam/Exhaust combo. You have to ask yourself...what RPM is the point where you run most of the time?

Since I had water ingestion in my previous 454's as I mentioned to you, I will have internal flappers in the tips as well as external(under swim platform)

Got my FWC kits today, engines should be ready next week and ,we agreed with my builder to dyno test both engines,(as recommended by Uncle Dave and other members)he would get me a quote on that next week.
Getting closer...

The cooling kits are black,should I paint them blue like the block? the exhaust manifolds from SM are already black as you see in the pic,any opinions?I am also considering painting the the covers in blue.any thoughts ?

Reversion probs dont get solved with closed cooling.

The closed system still dumps water into the header/manifold rails which (unless you run a dry tail) still mix at the collar or at the back of the tail.

The further back you mix the better off you will be as far as reversion goes.

I suspect with Madera picking your sticks you'll be fine unless the exhaust is already underwater and you back up a lot.

Looking good sir!

Uncle Dave

I would call SM before I did anything.

They design those manifolds to wear in a way that when they ultimately leak (They will give you excellent life) they leak on the outside not the inside. This means the outer walls are thinner than the inner walls.

This would make me weary about sanding them down, but maybe if you just paint over the outside you'll be ok.

I think their product looks like crap - but they work very well no doubt.

Like I said- call SM.

UD

Yeah they look terrible ;) Ok Ok I'll admit, they are a little plain, but that's the look I went for. I almost went with blue paint but decided with these manifold to go more understated. Though I really like the blue look too.

What are ugly, are my connectors...

http://i1268.photobucket.com/albums/...ps95144561.jpg

http://i1268.photobucket.com/albums/...ps31d2f248.jpg

BBC lib- do you boat in salt water?

Uncle Dave

Nope. Why?

EDIT: I know the boat was used in salt for some of it's life, that was evident when I rebuilt it, and the boat and trailer have flush system installed, which I eliminated from the block when the engine was out. The fitting is still on the swim platform in case I ever end up there for some reason...I can install the rest of it pretty easy.

The joker I bought it from used to run it on the hose with just the flush, moron, you would not believe the amount of impeller carnage I pulled out of it... He did tell me it seemed to eat impellers and I figured that out why when he started it for me. Some people just aren't that bright. That's part of the reason I got it so cheap I think.

Wasn't sure if there were a heat exchanger hiding under there somewhere for closed cooling.

If you aren't running closed cooling why run a recirculating pump at all?

You can pull a bunch of weight off, simplify the plumbing gain room to work on stuff, and put about 10-14 HP back to your mill by pulling of the recirc pump.

UD

Because if it ain't broke don't fix it. If I was worried about 10 horse, I would've put some rebuild the top end every 200 hours cam in it ;)

And more honestly, with an OMC drive I couldn't get a good answer if it worked ok.

yeahh.. I totally get the aint broke dont fix it...
...but youve fixed a good amount that wasnt broke already..

exhaust, Intake manifold, ignition, carb

OMC eh? ..uh yeah.... agreed there!

UD

I only fixed it since one of those silly main bearings failed, and I couldn't call myself a man if I didn't do something while it was out :)

In fact the OMC impellers are so hard to come by most people are putting engine driven pumps on. I'm not changing anything until I run out of parts, 72 mph is fast enough in the old girl!

This is what it looked like when I bought it. Not a whole lot of these got made :thankyouthankyou:

http://i1268.photobucket.com/albums/...pse2c4b203.jpg

Manifolds were on it.
Spitfire ignition was acting up, had to go, went MSD which lasted about a month, then DUI ever since.

Do you guys think i could reach 80mph with my Nova? With the stock 454's i was doing 70mph without opening it completely , too bad they got water in and had to get rid of them.

Rule of thumb is 20HP for 1 MPH- and you are asking for 10 MPH.

You're probably picking up close to 200 HP in total (assuming each side can deliver about 450 HP..actually youd be better if you can deliver 450lb/ft) and pulling weight of the rear so you are in the ballpark.

That rule "holding" or not will be very dependent on your hull. It may be fairly straight and youll be able to push it to 80, or it may be loaded with hook and or rocker to keep it on plane at a low speed and even an anti matter reactor wouldn't push it there - I just dont know.

You'll have to do some prop work as well.

Uncle Dave

80 isn't out of the question, but you'll need the right props. Get something on there close and then you can talk labbing etc. I didn't think that Nova had a hook, have you ever checked it? If it does, then I say no...

Diego...hook or no hook...when you're past 60~65 that hook if you have it isn't in the water. I know with my 272 LS with 640 Horse Power (Twin 320 EFI SBC's) I could squeeze 75 from it running 23" Cleavers at close to 6000 RPM. I chased my boat a few times with a friends 35 Cigarette Mistress....the 272 hull was barely in the water at 70 in 2~3' seas. I had the trim tabs in the factory location outside next to the chine and they became useless at that speed because they weren't in the water.

I think 80 is possible with the right props...but you will have your hands full. Chine walking is some scary $hit the first time you feel it and takes some practice to trim your boat to minimize it.

For my money...your best focus isn't on what it will do as an absolute top speed but rather propping it to run long distances at 50~60 MPH. The beauty of the torque and power your building is to reliably be able to run 50~60 MPH.... hours at a time with out straining the equipment...or your peace of mind.

When I get you running with me across 60~70 miles of open ocean in a bit over an hour you will come to appreciate what I'm talking about. I used to run that '86 272 from the Ft. Lauderdale/Port Everglades Sea Buoy to Bimini Harbor in 45 minutes...we had a group of Formulas, Donzi's, Novas and Scarabs called the "Bimini for Lunch Bunch":evilb:

I have to say...running a sweet running sport boat across the Gulf Stream between Florida and the Bahamas at 60 MPH is one of the best feelings you can have...with your pants on:evilb:

I would think that would depend on where the hook is.

I would agree that above 60 "hook" on the mid to forward 3rd of the boat is meaningless.

If the hook is on the rearmost 1/4 of the boat then it can be quite meaningful on some boats- others not so much.

One story...

http://www.offshoreonly.com/forums/b...29-outlaw.html

Sprinks description of the tabs being useless at speed is the reason I mounted mine the way I did.



UD

Mill before and after crossover installation...

Much simpler but a freshwater only deal for sure.

Uncle Dave

Agreed, generally I refer to a typical hook as one on/near the transom. Very boat dependent. I've seen boats with enough hook to stay on plane at so so low of a speed it's ridiculous. Getting to 80 would be near impossible on something like that

i like the way it looks , how much $$$ for a set of those tabs?

John,

I would love to see that happening , will go see the boat , i have no clue if it has a hook or not , excuse my ignorance.

i agree with you on the cruising speeds !!! that is the best part of it.

Nice job. Can't wait to see final numbers both dyno and water. Some good ideas for when I redo my 272. Still undecided between 383s and 355s. Will definitely do bravos and completely redo bilge area.

If anyone has pros an cons between the 2. Love to hear it. 383s obviously more power and my guess is slightly less in the longevity dept.

Diego and I have talked about this. Either is going to be strong with the 383 inherently able to produce higher torque numbers due to the stroke. The slight advantage that the 355 has is the ability to rev more quickly and produce less wear due to the shorter stroke and less piston travel.

All this considered....if you're starting with a clean slate and moving to Bravo anyway...you must take a look at building twin LS motors from 6.0/6.2 truck base engines. They are becoming more plentiful having been in production for ten years and are far superior in all respects to Vortecs. These engines can easily produce 500+ horsepower reliably due in no small part to the 6: bolt "splayed" main bearing caps. Parts to marinize these engines are available from Marine Power, Indmar, Crusader and others.

The source vehicles for these are Cadillac Escalade 2002~2013, GMC Yukon Denali 2002~2013, Chevy Silvarado with the High Performance option and of course Corvettes and Camaro's.

I am an old school Drag Racer and keep an eye on what the kids that run the streets are doing. The trend is to find an old "Box" Impala or Malibu rear wheel drive and transplant one of these LS engines complete with the computer and transmission. I occasionally go to Moroso Drag Strip here in West Palm to stay in touch and I have seen several of these rigs running high 10's with near stock motors!! I asked what their parts sources were to build these cars and was told to check craigslist.

So....
http://miami.craigslist.org/pbc/pts/3331374533.:evilb:

About $2000 puts you in business.

I will build a pair these for my next project without a question.

I like the ls series. Going back to the smaller in the camaros an firebirds. They were a vast improvement over the lt1 which I had and was near and dear to my heart. Lol.

I don't figure try are built to run with carbs. I don't wanna add anymore under the hatch. Like the simplicity of carbs. Don't wanna switch to fuel injection. Thinking of some nice 400ish or more 355s with bravos. Like you got. Not doing the motors anytime soon. Mine run strong right now an she's clocked a best of 63 on GPS. Avg 58-60. Right now it's about cosmetics. Interior. Gonna redo some stuff on transom to clean it up from removing silent thunder box and o with a teak platform.

Sorry to go on. Back to your thread Diego!! Lets see some numbers!!

PM to you...

Hate to cop out here, but I cant really say as I had them and billett tab pump housings put in at the time of the build.
I remember wincing at the checkbox on the order form though.

As for building engines for boats there are so many great combos its hard to wrong these days.

Whatever gives you the most torque from idle at 800 RPM to 5500-6 RPM for the least amount of money is what I go for.

Guys get way to caught up in the HP# when they should be working on the torque curve.

That usually means the most cubes I can get for my dollar - the smaller engines almost (not always) have to spin faster to make the power , and to get to high rpm you have to work all the way through the curve. Its just easier to go as big as you can when it comes to boats.

My "old fashioned" 23 degree 406 with a carb was built for cheap (for sure with good parts) and blasts my 21ft tunnel to 90. A rare plateau for a pump gas n/a small block boat.

I agree with Sprink- there nothing like effortless cruising. having a bunch left under the stick while sailing along is an amazing feeling.

I PREDICT YOU ARE GOING TO LOVE YOUR 383'S!

Cant wait to hear how she runs - give us some sugar buddy!

Uncle Dave

I will check tomorrow with my builder , we should be ready to dyno them by Friday , we'll see !

Hopefully you are right about these 383's , It has been a tough road with lots of changes and decisions $$$$ which at the end we will see if it was all worth it.

If your engine guy held up his end of the bargain, I would say you won't be disappointed. You've done everything right, it's not often you say that this "deep" into a build thread.

Lot's of people are waiting to hear how this turns out, it's like you have your own cheering section :D

Do you know how to check? If not, a typical transom hook literally "loops" down near the transom, the easy way to check is to take a straight edge (I use a yard-stick) and at the transom lay it flat on the bottom of the boat. If the yard stick touches the hull the whole way, it's flat (no hook), if you have a space between the transom and the forward end of the yard stick, it's hooked. The hook may not be easily seen until you hold something up to it, then it will become VERY obvious once you have a point of reference.

This hook acts like a trim tab, and allows heavier underpowered boat to get on plane easier. Some manufacturer's will have a very SLIGHT amount of Hook or Rocker (this is a whole different discussion) designed into their hull to emphasize certain performance aspects, or more commonly as a band-aid to try to save a bad hull design. Many older boats have them, I do not recall if your does or not 100%, but I do not THINK that it does. Sitting on a trailer without the transom supported and all sort of things can cause a hook that was also not originally there.

Here is a good picture I found a while back.

https://www.dropbox.com/s/2icg9wjm5cp9cic/hook2.jpg

I tried my best, invested lots of time,money and energy into this project. I am really getting anxious now...

As far as the hook, I will get that stik and check if there is a hook or not.

Thanks for the support.

fixx
 

i take a string and duct tape...tape the string the the front pull it tight on the transom and tape it their and look for the hollow spot..