New Drivetrain: need help deciding on engine 950hp BBC vs 700sci
 

Hey guys, I have a 30' Eliminator Eagle (single engine). Currently has a 496HO/Bravo 1 installed from the factory. I have decided to repower her and have been going back and forth for days on which power-plant to choose.

I have already decided to go with the Arneson ASD7 kit to replace the drive so that is settled.

I am looking at a used and complete 700sci with low hours on it vs an all new hand built 632BBC with all top shelf components making 950hp. The cost is equal for both. The logical choice is to go with the new engine and more power. But then comes the question of which will be more reliable in the long run. The mercury is arguably the better choice here but then again it is a used engine. Being that I regularly tote my family around in the boat, reliability is a big deal to me (for their sake). For me to justify a complete repower however, it has to be louder and much faster!

I'd appreciate your thoughts on this topic.

I'd do the 700. Great engine, great upgrades out there from whipple for them, etc. Performance Boat Center has a brand new one with headers and all the warranty for $40k OBO.

700 sci, then you can always do the upgrades, stage 2, etc.

A 950HP 632cid is a beast of an I/O pleasure boat engine. Race gas ? How aggressive of a cam ? Valvetrain life ? Idle/docking characteristics ? Dry exhaust ? How much do you trust the builder ?

@ 950hp you'd need to have the builder on retainer.............I'd go Smurf power.......... What kind of power does it take to spin a Arneson ASD7 ?

I also vote for the 700.

Great motor, proven trustful, lots of upgrade options. Just a great power plant from Merc.

All things equal, I would rather own a Merc 700 SCI than a custom motor - the resale will be better and should be more reliable.

Having said that, boy you really have to be careful who you buy used engines from. How well do you know the seller?

If you want, you can follow along in this thread as this boat and engine are built. 665 inch custom big-block, you may or may not find it interesting. http://www.offshoreonly.com/forums/g...low-along.html

The 950hp 632 would be pump gas, good size cam, solid roller top end with isky and dry exhaust. Have not had an engine built by him before. Customers do have great feedback (even when something goes wrong).

All good info guys, thanks. Good point: 700sci now, stage 4 upgrade later if needed. What is the official rebuild period on the 700sci. I've searched on here and seen anything from 250hrs to 600hrs..

As mentioned we have one brand new, never fired HP700sci in stock with exhaust. I am asking $39950, Merc retail is 60k plus. Will entertain offers. Its blue in color. Full Warranties.

[email protected]

single Arneson on a V bottom ? You mite what to look into this , I think Weisman has a surface drive with a duo prop for single engine applications .

I'm eager to see how this setup works with the arneson. Are you going to run a cleaver or bravo style prop?

Contrary to my usual opinion, I'd say go with the 700sci. Easy to make into 900+ down the road. I'm usually all for aftermarket custom built motors (more so against merc racings prices) but a big NA motor with a solid roller cam presents its own issues. You'll be setting valve lash often which requires taking the headers off (unless you get 2 piece valve covers) so that's quite a job. Also, to make a big inch NA motor you can have water reversion issues from the cam, the pistons are weaker from the wrist pin being so high etc etc. those motors work well in cars where the load on them is significantly less, but a 30' heavy single engine boat is about the harshest environment you can put a motor in.

Any feedback in I/O boats ? A Chevelle or etc is a whole 'nother boat...pun intended.

YUP.

Car guys rarely get marine stuff right the first time. Especially I/O's.

We're on pins and needles wondering what Bups new guy is going to deliver on that project.

I got unlucky a few times having car guys build boat engines for me. They were all smart good builders - with little to no marine experience.

VERY cool project Im eager to see it unfold - congratulations Turbo Raven!

UD

Some random thoughts, worth exactly what you pay for them, and your mileage may vary.

I think the IDEA of dry (loud) exhaust is probably better than actually having dry exhaust, especially in a boat doing double duty as a family boat. Forget communication in the cockpit if the engine is running and I hope the area where you boat is a lot more lenient on noise than where we boat.

The Merc is undoubtedly going to be better for resale but I don't necessarily believe it's a given that it will be more reliable than some of the custom builders. I've lived on a lake all my life and have had my share of service headaches with stock power. Even wimpy stock power.

If you're going to do custom power, I'd stick with a "name" IE Boostpower, Teague, Pfaff, Carson, etc. Someone who specializes in marine applications, not the local drag race or toilet bowl racer hot rod shop.

We have a 600 CID / 900 HP BoostPower package and it's never so much a coughed wrong. It starts every time, idles, and pulls like a freight train. When I've had questions I can make a phone call and get Alexi on the phone. Try that with your Merc. It's also a much "cooler" package and if we're being honest, the cool factor is a huge part of performance boating. Nobody "needs" a performance boat. We want one. The custom engines are finished off so much nicer it isn't even funny.

Remember if you're dealing with a custom builder, it probably has to go back to them for service, and you can make a dyno show some really impressive numbers without it being realistic useable HP. See my comments about a reputable shop who specializes in marine power.

At the end of the day it's about what you want & can afford, and makes you and the family feel good at the lake. Or the show & shine. Or wherever.

Between the choices you've floated out there, I'd probably go with the Merc for all the convenience reasons.

Throw (for me) BoostPower into the mix and that would be my choice because I've dealt with them.

Good luck & whichever way you go post lots of pics and have fun.

Cheers

email sent

Thanks Brett! Email sent.

Have done quite a bit of research as well as talked with owners and Rik. Should be a clean, fast and most importantly-indestructible setup.

Will be an offshore cleaver or hering prop. I'm no stranger to setting valve lash as I have a 950hp n/a LSX (solid roller) in my street rod currently. I hear ya though, def more maintenance required.

Thanks for the input. Yeah, I fully agree: good auto engine builder X= good marine engine builder.

Thanks for the input! Yeah, no noise complaints to worry about here in Hawaii. Glad you have had good luck with your NA BBC and I agree with you: all depends on the builder and their marine experience. I'll give Boostpower a ring to review options. I'm also that guy who always likes to have something a little different that everybody else. However being in Hawaii, I don't want to be shipping a custom engine back and forth across the pond..that adds up quick and too much downtime..

If you're in Hawaii and using it in saltwater all the time is another plus for the 700 with closed cooling. still needs to be flushed good after each use but you won't have to worry about the heads rotting away.

Dito. A friend of mine rigged his Batboat 28 with ASD - did not work well. Went to SSM6. Turbo Raven - take A look att SCX insted.

Either engine choice would definitely have a closed cooling system. Open cooling is not an option out here if you want to be on the water and not rebuilding engines each year..

Thanks for the advice Mange. I originally was going to run an SCX. In speaking with the manufacturer, I didn't like that there is no warranty and also that they require regular maintenance (bearing and gear inspection and replacement) when running moderate to big power. I have read every thread on the site about the arnesons on single setups (both V and cat). Seems like they can be very picky on what prop you are spinning and there is trial and error involved in finding the right one for the boat. As far as a #6, my short engine bay in the eagle 30 doesn't allow for moving the engine forward to fit a trans for a #6 drive.

Also, I spend a lot of time out at our sandbar here with the boat backed up to the sand to allow for passengers to easily get in and out. This has caused the demise of the bravo gimbal ring as the leg sometimes bumps the sandbar. With the arneson, I wouldn't have a "leg" hanging down as low to worry about. I am building a large swim platform that extends past the arneson drive and also running the arneson prop guard.

Just because a builder claims to be a marine engine builder means nothing not one ounce. IMO many engine builders including marine engine builders are not all of that in a nutshell. I am not refering to anyone in particular here but will add there is combo builders out there for auto and marine that some are very good. Boostpower, Paul Phaff, Reyer & Morrison build other stuff beside marine engines.

Reyer & Morrison inwhich you think drag racing only but could and would hang with any builder listed in this thread very easily without breaking a sweat thinking about it. Evan Dart could build you a very great marine set up if you wanted to throw down the cash.

I do know Boostpower, TCM, Reyer Morrison and Throttles Performance are not using Holley EFI set ups on any builds like many others because of its limitations.

I am using Throttles Performance in Fargo North Dakota area for the 665 CID build, no super charger or turbo for the build, Do not want it.

Without a doubt I have 110 % confidence that Mark at Throttles Performance can handle this without any problems, again without one doubt. We have him as well for tuning and his tuner friend. An FYI he tunes or has tuned for everything with a big name on it.

I am going full custom with all of it. Can have it built stronger and better and alot cheaper than any marine OEM plus tuned without all those OEM limitations from Merc.

Take that SC off the merc 700 SCi and you got not much, Most can add an instant 125 to 175 hp by adding a SC to the build mix but have them do it without and see where you end up.

Im going to say the opposite or everyone else....go the custom BBC route.

There are 2 guys local to me, one with 600SCi's and another with 700SCi's and both are having issues with going into guardian mode. Both of them have whipple upgrades and both have the updated water line routing done and still have issues.

Some people may have them or have had them and theyve been great, but to me, unless you keep them 100% stock then they arent reliable anymore. Any what fun is stock after a while?

I agree that the resale may be better with the blue motor, but if you think about it, after you change it to surface drive, change the engine/rigging, etc etc, how much is it really going to matter if it has a blue motor or not at that point?

Good luck, sounds like a cool toy

You Throttle's Performance ?

I recognize the 900HP forum member name from other places.

Make sure you get a really long dock pole. That should be hell around the marinas with a hugeblock. Get it pointed in the right direction and start it.

^^^^ 100 % wrong if you have a tuner who knows how to tune for all of that no problem - no matter of CID plus cammed correctly. Certain current stand alone ECM's its all possible to tune for whatever but and the but is again the tuner needs to know what in the hell they are doing plus set it up on the dyno then finalize it on the water testing with fine tuning. So many marine tuners still using MEFI 3 and 4 and a few MEFI 5's out there - such outdated, 10 to 15 years behind the times.

Boostpower is using AEM and has never looked back.

We are going to use MS3 PRO. If wanted to, we can idle the 665 at 750 rpm's. Prob 900 rpm's is most likely to have better oil flow and better water flow thru the engine.

And I agree with closed cooling hugely for marine engines no matter of CID.

Well the search is over for now! After speaking with Brett, I ended up picking up his new 700sci.

With several inter-island trips per year (open ocean navigation), reliability is #1 especially with a single engine setup. So I will sacrifice some power for this peace of mind...for now.

Appreciate everyone's input!

Congrats and keep us posted on the progress!

Large cubic inch motors require cams with a wide LSA. This really helps with idle. We have no problems getting big motors to idle under 500 Rpms in and out of gear with a carburetor. You can really turn the idle down so low the motor hardly runs. Couple that with a big arm spinning around and the motor doesn't even flinch when you drop it in gear.

There is no peace of mind with a boat only a lighter wallet. A well built 632 with a carburetor or two on top is a much more reliable peace than a fuel injected motor especially a Mercury fuel injected motor. Sounds like you spoke with a good salesman.

The guys made his choice, why people get all offended when they don't do your route is beyond me.

Good luck with the build, sounds really cool, I'll be in Hawaii in February :)

+1

I should keep my mouth shut, but I've never been good at that…

I've run carbed motors, both on gas and on alcohol, and yup, they were dependable.

But to say a carbed motor - even a well set up one - is "much more reliable peace" than a fuel injected motor ?

I think that's a "bit of a stretch" and will admit that isn't the first phrase that came to mind.

Carbed motors have to be set up correctly to be dependable.

Injected motors have to be set up correctly to be dependable.

Either is a piece of **** when it's broke.

But, in my opinion, the biggest difference is this: carbed motors have to be tuned for the area and conditions they're going to be run in.
We aren't talking about some wimpy stock motor in an 18' family bowrider tuned so wide it doesn't matter where in the country it's being run.

We're talking about substantial cubes and relatively high performance. If you have a dual carbed, 600+ CID motor tuned so it can be run in any conditions regardless of altitude, temp, or humidity, it aint "set up right". That's just the math, and math isn't an opinion.

I've got a 600 CID, compound blown, electronic efi Boostpower engine that doesn't so much as hiccup. It can be run anywhere in the country, and if I do have an issue, if I've got wireless access Alexi can tune it remotely from his laptop. I'll put that reliability up against any carbed motor any day of the week in any conditions. And it's no trailer queen, it gets run weekly and hard enough that I have a spare outdrive because that's the weak link, not the motor.

I'm not trying to start a pissin' contest, but why are you trying to rain on the OP's parade?

He asked for advice, made a decision, and is obviously excited.

"Sounds like you spoke with a good salesman"

That sounds like a disgruntled salesman that lost a deal. You the guy trying to sell him the carbed motor?

I'm sorry for the rant, but WTF ? This kind of BS is exactly why OSO has people defecting to other forums…

Looks like I'll be following them…haters just gotta hate, i guess

I just wish my big problem was deciding between a stock 700hp or a 900+hp engine. That is one problem I could deal with!!!

Someone (me) needs a bigger boat budget :)

Yup. busted. lol.

Although I would have gone custom (on my last build I went to Boostpower like slippery) there simply were no bad choices here.

The Merc 700 is a great package and what foibles it may have are well known and with a few changes it can become a fire breather.
The poster should rightfully be very happy especially if he got a clean low hour unit.

UD

New, with a warranty even. I think...

Congrats Turbo,

Here is what a merc 700 sounds like - its nasty.

The vid kept changing aspect ratio, but you can get a good idea of how raspy and mean the merc 700 is.

The blue 39 with windshield has 2 of them and goes like a bat out of hell with cleavers.
The boat on the left a Lavey 29 has a teague 800 in it thats been sweetened a bit and is nasty as hell
Im in the middle with an Ilmor 710 on 2" CMI's with Gatlins.

Bup is sitting on my left.


https://www.youtube.com/watch?v=LUOM...ature=youtu.be


UD

[QUOTE=Uncle Dave;4474548]Although I would have gone custom (on my last build I went to Boostpower like slippery) there simply were no bad choices here.


Correct; a new, never fired unit complete with headers and warranty. Couldn't be happier.

Sweet sound clips! Thx for sharing. Getting excited to get the new powerplant in there to hear the same music!!

All I will say, for what little it might be worth, seems that more often than not the aftermarket big gun builders come up with some numbers to make your sticker peck up, put the biotches in the boat and they fall on their face. I know of a couple of my own brand that have run better numbers with stock Merc Perf motors than they run with the other guys monster chit.