Small Block rebuild
 

OK....I need to go 80+mph; should I:
a. Rebuild my 99'350MagMPI's into 383's NA?
b. Rebuild same into 383's w/superchargers?
c. Sell current power & purchase 383's complete(less exhaust)?

I wish $$money$$ was no object, but the whole reason I want to keep the boat is I love the fuel eff. of the twin small blocks. Also, the 28AT is big enough for ocean, it destroys the rough stuff and small enough to trailer anywhere w/o much stress on truck or wife.

If I decide to rebuild:
a. who to use?
b.Who to AVOID?
c. Who makes the best rotating assembly for small blocks?

Thanks in advance!
Spil

Chris,
I pm'd you my opinion. Leave the engines alone and install the sc.
In order to make over 400 hp with a 383 ci, you will not reuse the vast majority of your parts. You could certainly make over 400 hp with a 383 ci, thats not the problem. The problem is, you will need to replace the crank, rods, pistons,cam, valves,gaskets, oil pump, oil pan,timing set,rings, bearings, springs, retainers, keepers, rockers, injectors, possibly the heads, etc..plus all of the machine work.
You would do much better to start over from scratch and sell what you have. You will only reuse maybe a thousand or two dollars worth of parts. They are worth more than that if you sell them. I don't ever recommend messing with stock Merc engines except for installing an sc. They bring good money in stock trim. If you modify the engine and try to sell it, you will have trouble selling it. If you install the sc and want to sell, you can always remove it and return it to stock.
The sc will give you the most bang for the buck. I have done several and they are dynamite.(both the Procharger and Whipple) I like the Whpple a little better, but the Procharger system is very good to. The Procharger is cheaper, but the Whipple looks nicer. Either system will get you 450+ hp.
Let me know if I can help you. Thanks, Eddie.

More HP is going to burn more fuel...period.

I bored and stroked a set of 500's and agree with the above statement. For just a little more money I could have started over from scratch and sold the stock motors. Keeping the fuel injection looks cool (to me), but I could have made more power ditching all that stuff.

OK. How much are my engines worth? I know; they're worth what someone is willing to pay. So where do I start? Is $4,000 each, $7,500 pair about right?
They have 400hrs.....

I only have one question:eek:

How much HP is it going to take to get that boat into the 80MPH range you are looking for:grinser010:?

Sell your engines and get a pair of Raylar's LSM 550's!:evilb:

Oh, wait... you said money IS an object...:p

I just would like to get a report on how those things run. That would be one hell of a combination in your boat.:cool:

Seriously, I would opt to build engines from scratch and pull your stock engines untouched. You can sell them or keep them as back-up, and if you decide to sell your boat, put them back in and keep your high performance powerplants. You can take your time and build (or have built) from scratch naturally aspirated big inch small blocks that would easily get you over the 80mph mark. Why settle for 383ci? Done right, 400ci+ torque monsters would be the way to go.

$RaylarLSM550$
 

No Doubt, That would be AWESOME! However, not realistic...I would guess the 550's would put my wot speed close to 100.
My current motors are stock(300hp @ prop) except for exhaust and I can see 72mph in ideal, fresh water....salt might get 73.5-74mph. So with 400 hp per side I'm @ 82+/- 1.5mph, all things considered...every 20hp = 1mph, (except for the most important fact-it's a boat & you just never know!)
With 425-450 per side, upper 80's seem realistic; but we will find out when we get there.

Now, After a few quotes for 383's, natural asp. I am back to sc's and top end freshen up.....wtf!@#$%%$!?
BTW, What are a pair of 350magMPI's w/400hrs worth???....

With 400 hours... not much.
Just slam some blowers on there and have fun!

Put these in! 820hp and the best of everything. 80mph will be no problem.
http://www.offshoreonlyclassifieds.c...o26350-en.html

Now that's taking it up a notch!! :evilb:

I always thought a pair of big inch N/A small blocks in a 28' would be very cool. IMHO, Ralar 550's in a Pantera or Active Thunder would be quite the setup. Even a single would be no slouch. Doug

Just slam some blowers on there and have fun!:ernaehrung004::ernaehrung004:

If you go with blowers on the 350's, don't forget a good oil cooler. My 6.2's only hold 4.5 quarts!:eek:

Don't know what your 350magMPI's could be worth.

Spil,don't know what whipple's cost,but can't say enough good about them.240k miles on my yukonxl 5.3 and not one problem and get 17-18 mpg .I would think marine are just as reliable,major hp improvement. 55-60 is fine for me,if I needed more I would consider a pair of whipple's though. There my .02cent's

Thanks all, I am considering doing the Whipples, oil coolers & a top end freshen up....Like to hear from anyone else w/sc small blocks and their experiences.....good & bad

My $.02........At 400 hrs I would really consider re-freshing the bottom end before putting Whipples those motors.

Some good advice
 

I've Been playing with blown small blocks for a decade.

I wouldnt consider "bolting" on a blower to a stock engine after doing it myself. Your 400 hour small blocks probably wont make it to 420 hours if you do this.

Young is right on, you need to go through the engine completely to do it and have it live more than a little while. My experience bears this out.

The guy that said remove your engines and save them and build a whole separate pair is giving you really really good advice- its the most flexible way to sell and own your boat- but this costs money.

After a lifetime of doing projects like this the only way to do it is to be really honest with yourself about your budget lock and realize- everything works backwards from this number.

#1 determine how much money you have
#2 determine what you can actually do yourself so you can stretch the dough

Budget determines EVERYTHING-

Hand selected parts vs. parts kits (this also answers another question of yours) , a 383 rebuild vs say a world products 454 short block. With VERY few exceptions go as large as you can with the cubes for the money you've got.

You can get a pair of 425HP 383's long blocks from Scoggin Dickey for 4995 Each- or you can buy a set of AFR' heads and an intake combo and wait till next year- pick up some ponies this year a few HP and finish in a year.....(this is brutal on the labor but a reality)

Without locking down a # you're pizzing up a rope and will get "analysis paralysis" with all the possibilities you cant afford.

I run a 500hp 406(brodix heads/demon carb) in my 21 foot tunnel hull- its a wicked choice as well.


Uncle Dave

Laveycraft 2750 -710
Laveycraft 20.8 Sebring

Spil,
I have been thinking of doing the same thing with my 28 challenger, with 350 Mags and 200 hours. The question I have is, is it worth it to install a Pro Charger on these and how long will they last before a major overhaul is warranted. I also want to keep the small blocks because of ease of working on them. More space to work with, etc. Mercury now has 383 engines, but I understand they are like $23k/each. Ouch!
Let us know what you decide. Ken

Spil,remeber the 4 t'2(if it's got t%t's,tires,transum's,tracks it's goin to give you problems)if you are going to run the dog **** out of it then start fresh. If you have a solid sbc and has been will taken care of talk to whipple and see what they would advise you to do..(thats .04`cents now)

Spilman,
I have a 21 ft Checkmate with a forged 383, AFR (180 Eliminator) heads, Bob Madera cam, and full roller valvetrain. So far I have picked up 21mph from the 350 that was in it when I bought it. If you repower for big hp NA motors, you will spend a significant amount of cash to build 2 stout motors to handle big power. If you want to build blower motors, again you will have to spend some big cash to build motors that can handle boost and HP reliably. Blowers will add complexity and time to the repower. How much time do you plan to spend at 80mph? I built my boat to go 80, but I find that I still drive it like I did when it had the 350 in it, which is mainly cruising. Most people I take out in don't get the same big kick out of going stupid fast that I do, so the boat spends 93% of its life running between 1200-3500rpm. What I am trying to say is that I wanted nothing more than a really fast, loud boat. Now I have a really fast, loud boat, but I am not getting $15000 more fun out of it. Yes I am really proud of my work, proud of how the boat looks, and I like how it turns heads, but having $10,000 more than I have now in the bank would be pretty cool too...

93% running 1200-3500 WOW how true that is.......