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View Full Version : Smallblock I/O vs. BBC jet.......



Jim B.
07-25-2007, 05:11 PM
What would the pros and cons of a BBC jet drive vs. a smallblock I/O setup in a new 21 bowrider like an ultra or essex?? My wife and I are looking and i'm trying to decide what would be better.............I mean I know a jet drive is going to cost less vs. an i/o in the same boat and is going to be less maintenance and safer(for the kiddies) but would a smallblock I/O get better gas mileage??
How is towing a skier between the two? I've never owned an I/O only jets so those that have experienced both please chime in.
i'm looking for a good all around performance ski setup that gets descent gas mileage. Going fast is not a concern........this is going to be a family ski boat....What are your recommendations??? Thanks!
JiM

Run_em_Hard
07-25-2007, 05:20 PM
Where do you boat the most???

pw_Tony
07-25-2007, 05:23 PM
An I/O would whoop the Jets azz on gas mileage!
Have you ever driven a BB jet?
I/O small block is more practical, but if you're a real boater then you have enough money for more gas right?:D
BBC jet is probably more "fun"
and a small block I/O is more user friendly I suppose, get you to the sand bar, tueb, and go back

Boa1277
07-25-2007, 05:42 PM
Take it from a big block jet owner who is probably going to convert to a small block I/O because not only will you get much better gas mileage you will probably get 10 more mph. (Depending on how trick the Big Block is) You can get a little small block pushing out 350 hp and you will run 65+ all day long.

pw_Tony
07-25-2007, 05:46 PM
Take it from a big block jet owner who is probably going to convert to a small block I/O because not only will you get much better gas mileage you will probably get 10 more mph. (Depending on how trick the Big Block is) You can get a little small block pushing out 350 hp and you will run 65+ all day long.
Obviously I'm not sure what kind of boat you have, but one of my fathers boats has a small block I/O, it's a 20' and can get a max speed of 45mph, trim all up, and a couple passenegers with no cargo.
And my friend's other cheetah 21' has a small block I/O and runs 48mph all day, not quite 65.
As for the average jet BB boat under 22' will probably do a good 55mph, but that's with a lot more holeshot, and fun factor :D
And a jet can plane alot faster

77charger
07-25-2007, 05:46 PM
I use to have a 19ft jetboat did fine for a jet but like most used some gas.Needed a better family boat so i searched for a 21 ft open boaw and wanted a prop wheter it was a454 bravo or 350 alpha.Found a clean 21 w 350mag/alpha combo(93 eliminator).Top speed is around 58 and on agood day can barely hit 60.with 8 people in it it can still pull 54-55,has no prob pulling skiers and gets on plane pretty good even if loaded heavy.But does not use much gas at all 35 gallons gos a long way with alot of drivin.
It will take a strong big block/jet in the same size hull to match my speed and i see some of them struggling with full boat to get on plane if they are trying to go against a strong current plus use alot more gas

dicudmore
07-25-2007, 05:52 PM
I/O all the way :D jet-drives are for sea doos not family cruisers

Jim B.
07-25-2007, 06:06 PM
Where do you boat the most???
Here and there and alittle bit of everywhere:D .................CA lakes and the river (Parker,Needles)

Jim B.
07-25-2007, 06:08 PM
An I/O would whoop the Jets azz on gas mileage!
Have you ever driven a BB jet?
I/O small block is more practical, but if you're a real boater then you have enough money for more gas right?:D
BBC jet is probably more "fun"
and a small block I/O is more user friendly I suppose, get you to the sand bar, tueb, and go back
Yes I driven a jet.lots of them. My last boat was an 18 ft. eliminator bubble with 800hp:D .............................. it's hard to compare that with a stock BBC 21' ultra bowrider

pw_Tony
07-25-2007, 06:17 PM
Well then you know about what they're good at!:)

rlemn8r
07-25-2007, 06:33 PM
I have a eliminator 210 eagle with a 496, 450 hp with a legend pump. engine is totally stock, run's 63 mph with 2 people aboard, has great storage, holds 50 gal. of fuel and will go all weekend with no fill up. The I/O might get a little more speed, or a little better mileage, but the jet is safer and has a great rooster tail...

OCMerrill
07-25-2007, 06:35 PM
I have a small block Merc Mag and an Alpha Drive. I have never owned a Jet Boat but have driven many. To compare is really difficult.
I can say for mileage my Lavey gets about 4 mpg average over a weekend on the Parker Strip verified by my totalizier on my hand held GPS. Two 20 gal tanks will last three days for me and thats driving not constant floating. I can run 70+ but I have a Tunnel Hull boat so small power works OK.

dicudmore
07-25-2007, 06:49 PM
the jet is safer? seriously?? just curious here...when not running how much friendlier is it to kick a jet pump than the gear case of a drive? they both hurt...

ChumpChange
07-25-2007, 06:52 PM
I/O all the way :D jet-drives are for sea doos not family cruisers
Wow, no comments from the Jetters on this? :eek:

bordsmnj
07-25-2007, 06:53 PM
I have a eliminator 210 eagle with a 496, 450 hp with a legend pump. engine is totally stock, run's 63 mph with 2 people aboard, has great storage, holds 50 gal. of fuel and will go all weekend with no fill up. The I/O might get a little more speed, or a little better mileage, but the jet is safer and has a great rooster tail...
don't put a gps in that boat you'll lose 10 mph. no bullshit.

ChumpChange
07-25-2007, 06:55 PM
don't put a gps in that boat you'll lose 10 mph. no bullshit.
Those GPS systems sure do weigh a lot. :D

pw_Tony
07-25-2007, 06:57 PM
the jet is safer? seriously?? just curious here...when not running how much friendlier is it to kick a jet pump than the gear case of a drive? they both hurt...
Sometimes when I want to get on the boat I'll stand on the jet pump...
But I can show you my scar on my hand from a prop

XtrmWakeborder
07-25-2007, 07:08 PM
Obviously I'm not sure what kind of boat you have, but one of my fathers boats has a small block I/O, it's a 20' and can get a max speed of 45mph, trim all up, and a couple passenegers with no cargo.
And my friend's other cheetah 21' has a small block I/O and runs 48mph all day, not quite 65.
As for the average jet BB boat under 22' will probably do a good 55mph, but that's with a lot more holeshot, and fun factor :D
And a jet can plane alot faster
Those must be horrible hulls because my 85 mini daycruiser does 53mph with a jet and and the original 350. Thats real world also, not one person and fuel vapors.

Jim B.
07-25-2007, 07:10 PM
Sometimes when I want to get on the boat I'll stand on the jet pump...
But I can show you my scar on my hand from a prop
I second that........
I'd much rather bang my leg on a jet pump rather than a prop!:D

Insurance God
07-25-2007, 07:22 PM
the jet is safer? seriously?? just curious here...when not running how much friendlier is it to kick a jet pump than the gear case of a drive? they both hurt...
Good point. :)

rodnjen
07-25-2007, 07:36 PM
I have owned both and I can tell you without hesitation the 21 Essex with a 6.2 Bravo III is a great all-around family boat. It actually planes faster than many jets with less effort. It is a little slow out of the hole with 250 lb. skier on a 69" 30-year old O'brian, but my brother weighs 80 lbs. more than when he bought the ski.
We run 2 1/2 to 3 days without refueling and the Sterling handles the chop better than any 21-22 (with average freeboard) than anything I have been in. Another thing I always mention, but take sh*t for it sometimes, is the reverse facing seats. It is very nice to have the option to face the other way. You will find few 21's with similar interior room.
I cannot say enough about the performance, versatility, docking or general handling of the Essex. PM me if you want to hear any more. I'll give you my number if you want to take the gloves off and have an honest discussion without the drama and I'll send pics of my boat.
Rodney

pw_Tony
07-25-2007, 07:55 PM
Those must be horrible hulls because my 85 mini daycruiser does 53mph with a jet and and the original 350. Thats real world also, not one person and fuel vapors.
Well I know for sure that my "mini daycruiser" spectra did 54mph G.P.S
53mph with a mini day and a jet is actually imressive, check out "just jets" section and I think there was a guy on there talkin bout his 350/jet combo doing bout 47mph

ahhell
07-25-2007, 08:30 PM
Well...I have a 21 foot 454 jet...It sucks the gas down, it does an honest 50mph with 4-6 aboard, I have never cut my foot or any other part on the pump or skag (bruised a shin though)...BUT.. I do travel the river between Laughlin and Havasu and have never torn up a prop:eek: ..OK i have busted a hydraulic ram for the diverter!
it fits my needs since I live near the River and love cruising it:D

yopengo
07-25-2007, 08:33 PM
BBC and a jet. More fun and better in the river any day. :D

SandbarScot
07-25-2007, 09:45 PM
Quote:
Originally Posted by rlemn8r
I have a eliminator 210 eagle with a 496, 450 hp with a legend pump. engine is totally stock, run's 63 mph with 2 people aboard, has great storage, holds 50 gal. of fuel and will go all weekend with no fill up. The I/O might get a little more speed, or a little better mileage, but the jet is safer and has a great rooster tail...
don't put a gps in that boat you'll lose 10 mph. no bullshit.
Jay, I can get over 60 in my Ultra with just 2 on board. I'm guessing she has about 425 HP

pw_Tony
07-25-2007, 10:10 PM
My other buddys got the 20somethin Carrerra, with a 502. It's a bitchin boat, but we couldn't get faster than 56gps :(

Ziggy
07-25-2007, 10:30 PM
I went from a 454 jet to a 6.2(377) I/O.
Jet would do 50-55 with major concentration on water conditions and boat attitude.
I/O will do me 55-62 depending on loads with a single hand on steering if I want.
Jet was 20'
I/O is 23'
Got pounded in the kidneys and back in the jet.
I/O ride quality is thousand times better.
.
As a comparison: I ran from Cottonwood cove to Hoover dam with a friend who's boat is a 21' Jet(496 I believe)...we didn't race around much and water conditions perfect midweek. On the way back down we stopped at a beach for a while and I took the kids tubing for a good 1/2 hr.
By the time we got back to Cottonwood he was on fumes, I had almost 1 1/3 tanks left(roughly an 84 mile roundtrip). Tanks in the boats are comparible in size. Hull designs comparible as well sans the 2 foot length difference..
.
I miss the fun factor in the jet for spinning or sliding the boat and certain low water level operation....oh and the rooster, but the fuel savings, and ride quality overshadow these small losses 10 fold.

Legal Chemistry
07-26-2007, 10:00 AM
I have a HUGE jet... 24' (or 25'???). With a 454 and full gas/people it will run 50 all day, and about 1.5 mpg for the most part. A similar boat w/bbc and Bravo 1 runs ~60/63. I don't think for my particular boat a small block would get the 10mph that some claim.

rivercrazy
07-26-2007, 11:04 AM
I've also had both types of propulsion. For purposes of comparision, take a 21' 18 degree bottom that just about every builder uses with a 496HO 425hp engine.
* A jet drive will do between 55-58mph with a very light load.
* An outdrive will do at least 73-75mph.
* A jet drive will be screaming at 4K rpm to go 37-40mph.
* An outdrive will be loafing at 2,800-3,200 rpm to go 40mph. 55mph+ at 4K rpm is easily doable.
* A jet drive will burn through tons of fuel. 1-2mpg is about the best you can expect if you keep rpm's below 3,500.
* An outdrive in a boat that size should break the 3.5-4mpg barrier at similar rpms.
* Load a jet driven boat with 5-8 people and watch performance in all areas nose dive (i.e. top speed, handing in chop, etc)
* An outdrive will not be anywhere near as impacted by a similar load.
* A jet drive in 2' chop will bruise your kidney's. Jet's just don't have the dynamics to carry the bow.
* An outdrive will ride OK in 2' chop. Outdrives carry the bow very well.

98 Vector 21
07-26-2007, 11:12 AM
Bbc....

beaverretriever
07-26-2007, 11:22 AM
A friend of mine here on the boards has a 21' Ultra with a 502 Indmar with Lightning Headers, that is also a Jet.
I had a 23xs Lightning I/O with the Merc 6.2 MPI.
No matter the load, no matter the conditions our boat would always slowly pull on him. Our boat ran 61.8 on GPS. I was guessing he ran around the high 50s.
His boat pulls slightly harder at start but within about a 100 yards I was leaving him.

spectras only
07-26-2007, 01:13 PM
Get an Ultra 23 with the 6.2 MX . Ask John to install the Bravo1 X drive with 1.65 ratio , so you could spin a B1 26 P prop .

SB
07-26-2007, 01:37 PM
I went from a 454 jet to a 6.2(377) I/O.
Jet would do 50-55 with major concentration on water conditions and boat attitude.
I/O will do me 55-62 depending on loads with a single hand on steering if I want.
Jet was 20'
I/O is 23'
Got pounded in the kidneys and back in the jet.
I/O ride quality is thousand times better.
I'm not disputing your conclusions, but that wasn't his exact question.
Make sure you define "small block" in your comparison. Your basic 5.7 engine is 260-300 hp. The scorpion is a lot more $.
The jet with the BB should pull a fat skier out faster.
The base small block should be about 5 mph faster top end, but there is prop selection as a factor.
The jet, with an A2 impeller, and stock BB, could get comparable gas mileage at skiing speeds. Mine does. Overall, the small block should get better mileage.
The outdrive boats seem to ride a little better. Can't say exactly why, the drive is like a fixed point that steadies the boat, while the jet follows the contours of the water.
If buying the boat for towing kids on water toys, get the jet. Someday your kid will want to take his friends on the boat without you.
I'd rather have an outboard than an I/O.

OverKill
07-26-2007, 01:56 PM
the jet is safer? seriously?? just curious here...when not running how much friendlier is it to kick a jet pump than the gear case of a drive? they both hurt...
It's not about KICKING the pump or gear case. It's safety for the kids and other peeps in the water. Perhaps some idiot forgets to put the prop drive in neutral and comes to close to a skier. Yep in the hospital for sure. A jet drive you can leave the engine running all day long with people all around the boat. Most that's going to happen is the thrust is going to blow off your swim trunks. And if its' gas your worried about, WHO CARES about a few mpg. You can't put a price on your kids safety.
Anoter example. A friend of mine was boating in Parker and hit a sandbar with his Out Drive. He has the whole thing ripped off the transom and to fix it was $7,000. Another buddy of mine ( a Jet Owner ). Did the same thing on the lower river. All it cost him was time to pull the motor flip the boat and reglass the damaged areas. I'm guessing here but the damages were probably no more than $500, and thats on the high side..
So if gas milage is all these guys can come up with then I wouldn't think to much more of the I/O. In fact Im running 72mph with a BBC, 19' hull loaded with 4 people, a dog, and a huge ice chest full. If you want to come out my way some time, I will take you for a ride and show you all the percs of a Jet Boat.

BarryMac
07-26-2007, 02:01 PM
I went from a 454 jet to a 6.2(377) I/O.
Jet would do 50-55 with major concentration on water conditions and boat attitude.
I/O will do me 55-62 depending on loads with a single hand on steering if I want.
Jet was 20'
I/O is 23'
Got pounded in the kidneys and back in the jet.
I/O ride quality is thousand times better.
.
As a comparison: I ran from Cottonwood cove to Hoover dam with a friend who's boat is a 21' Jet(496 I believe)...we didn't race around much and water conditions perfect midweek. On the way back down we stopped at a beach for a while and I took the kids tubing for a good 1/2 hr.
By the time we got back to Cottonwood he was on fumes, I had almost 1 1/3 tanks left(roughly an 84 mile roundtrip). Tanks in the boats are comparible in size. Hull designs comparible as well sans the 2 foot length difference..
.
I miss the fun factor in the jet for spinning or sliding the boat and certain low water level operation....oh and the rooster, but the fuel savings, and ride quality overshadow these small losses 10 fold.
That was a great focking day... :D :D Oh yeah, it's a 454 390hp... ;)

Legal Chemistry
07-26-2007, 02:03 PM
Get an Ultra 23 with the 6.2 MX . Ask John to install the Bravo1 X drive with 1.65 ratio , so you could spin a B1 26 P prop .
Yes, those 377's are great! But then one can argue a 502/500...
in the 5mph zones a jet sucks... my buddies 27' 502 B1 gets around the bend to the sandbar at a tick over 1k, mines running 1800rpm... that sucks. Then again I just point and shoot at speed because I could don't give a crap that it's a "bit shallow" on the way there! :D

jbtrailerjim
07-26-2007, 02:18 PM
My last boat was a 22' Essex with a 5.7LX (260hp) with a Alpha One drive. It pulled skiers and wake boarders great. Topped out at about 57 mph. I could fill it up (50 gal.) and run the hell out of it all weekend on that tank. It gave me zero mechanical problems the eight seasons I boated with it. If I boated on the lower river I could see buying a jet. But If you boat on lakes, I can't understand why anybody would want a jet in a 21' or bigger boat.

pw_Tony
07-26-2007, 02:20 PM
OMG this argument will go on FOREVER.
It's simple, if you plan on doing boating in shallow waters, then go with a jet! Otherwise it's not a question of IF you're going to replace pump, hydraulics, or a skeg..... its WHEN, cause you will
But if you're going to be doing some deep river, or lake boating than the I/O is probably the way to go, they don't get suck to the waves like a jet does, and doesn't risk as much.
Because gas can be argued over and over but if worrying about $20-$30 extra a day from one to another then you should be saving your money instead of boating

OverKill
07-26-2007, 02:38 PM
OMG this argument will go on FOREVER.
It's simple, if you plan on doing boating in shallow waters, then go with a jet! Otherwise it's not a question of IF you're going to replace pump, hydraulics, or a skeg..... its WHEN, cause you will
But if you're going to be doing some deep river, or lake boating than the I/O is probably the way to go, they don't get suck to the waves like a jet does, and doesn't risk as much.
Because gas can be argued over and over but if worrying about $20-$30 extra a day from one to another then you should be saving your money instead of boating
And the overhand right for the Knock Out!!!:D. Good call, it's all about what you want to do..

77charger
07-26-2007, 02:39 PM
I've also had both types of propulsion. For purposes of comparision, take a 21' 18 degree bottom that just about every builder uses with a 496HO 425hp engine.
* A jet drive will do between 55-58mph with a very light load.
* An outdrive will do at least 73-75mph.
* A jet drive will be screaming at 4K rpm to go 37-40mph.
* An outdrive will be loafing at 2,800-3,200 rpm to go 40mph. 55mph+ at 4K rpm is easily doable.
* A jet drive will burn through tons of fuel. 1-2mpg is about the best you can expect if you keep rpm's below 3,500.
* An outdrive in a boat that size should break the 3.5-4mpg barrier at similar rpms.
* Load a jet driven boat with 5-8 people and watch performance in all areas nose dive (i.e. top speed, handing in chop, etc)
* An outdrive will not be anywhere near as impacted by a similar load.
* A jet drive in 2' chop will bruise your kidney's. Jet's just don't have the dynamics to carry the bow.
* An outdrive will ride OK in 2' chop. Outdrives carry the bow very well.
Hey dave you are one who can give a good caomparison with the bbc jet and the small block i/o since you rode in mine.They arent the same brand boats but similar bottoms.

squirt'nmyload
07-26-2007, 02:43 PM
just buy both....end of story :D :D

455Rocket
07-26-2007, 03:18 PM
OMG this argument will go on FOREVER.
It's simple, if you plan on doing boating in shallow waters, then go with a jet! Otherwise it's not a question of IF you're going to replace pump, hydraulics, or a skeg..... its WHEN, cause you will
But if you're going to be doing some deep river, or lake boating than the I/O is probably the way to go, they don't get suck to the waves like a jet does, and doesn't risk as much.
Because gas can be argued over and over but if worrying about $20-$30 extra a day from one to another then you should be saving your money instead of boating
Well said...
In my opinion... get a bbc AND I/O if you got the cash. It's a freakin' BOAT!
You need cash to buy and to maintain an I/O. The bi-annual maintance bill on these things will eat up anything you saved over the same time period in fuel. Rebulid a jet for well under a grand... rebuild an I/O for :jawdrop:
If you like the river and love seat-of-your-pants type driving... get a jet.
And who the hell cares about gas?! You're gonna pay up the ass anyway! Put your foot in the throttle and enjoy the water.

pw_Tony
08-10-2007, 11:23 PM
:D
http://www.***boat.com/forums/showthread.php?t=160254

Redneck
08-11-2007, 03:35 AM
I have a 21 ultra IO with a small block get great gas mileage dont know much about jets so cant compare. Hit me up if you get to looking mine is for sale in the spam section.