Fuel Injected vs Cabureated

[backlash]

I'm debating on going carb, throttle body inj., or port injection. I've heard good cases for all. The motor will be a 350 Chevy, the horsepower gains seem substantial but will the benefit outweigh the cost. What about dependability. What's the straight scoop?

[Deleted User]

They both sound painful BL http://www.ifish.net/forum/images/graemlins/smile.gif. ... Actually, I've had the TBI 350 in a car and they work great for that application. Should for a boat too, but listen to the boat experts. - RT

[boater]

in my opinion the only thing you are saving when going to the tpi is some fuel, the tourqe rating is the same, the max rpm is the same, ive wondered how they can rate it as having more hp when everything is the same. it even says so on marine powers website under engine specs. if someone could explain this i would like to hear it.

[Fish4Fun]

I went with the Carb. on my 350, reason being if something were to go wrong out on the water you can tinker with it to get back in. When a F.I. unit goes down there is no way to mess with it. The only big advantage that I have found out between them is that on cold mornings the F.I. will fire up and run better. I didn't think the price upgrade was really worth it for no more H.P.

Fish 4 Fun

[Rippenlips]

Here it goes, if I can remeber all the reasons. Fuel injection may have the same max output but the torque and horse power curve will be better because the engine is getting the perfect fuel ratio. I do think the ported fuel injection will have a slight H.P. increase over the others due to the better atomization(sp?). TBI is very dependable but it is still like a carb when it comes to introducing fuel at the top of the manifold. Fuel has a hard time staying in a mist form. In terms of dependability, I would go with the Fuel injection. It is true that you can mess with a carb. when they fail, so that is a consideration. I have run a fuel inj. car on a can of brake clean and was able to drive it a small distance. I'm sure a drip bottle of fuel would start and run any engine. Cold and hot start ups will be better with fuel injection. I have a carb on my N.R. that I still don't have the choke set properly. Engine life will be longer with Fuel inj. due to not washing the cyl. walls with excessive fuel. There are probably more reasons but it is to early in the A.M. Hope this helps. Oh Ya better MPG.

[Salmonator]

My biggest reason for TBI was the ability to fire up and nail the throttle (hot or cold) in emergency situations. I don't think I could do a whole heck of a lot with a malfunctioning carb out on the water anyways (I never could get my 74 pinto tuned if that tells you anything) lol

[boater]

i would say go for a ride in some boats, some with carbs and some with tpi and see if you can tell the dif., i couldnt.

[nwjetboat]

The F.I will provide instant starts, hot or cold. It won't load up warming up when cold, it won't load up if you are idling for an extended period of time. It won't load up on steep ramps. I believe that at cruise, there is a fuel usage benefit also. I have a 454 F.I with a 212. My friend has a 454 carb with a 212. Same size boat, running same rpm, on the same river, one behind the other. I burn 8.5 gal hour, and he burns 10.
The TBI and the F.I. both use a computer to determine air temp, density, set fuel flow rates, etc.. So as far as easy to work on its carb or hi-tech. They do have a "limp home mode" like the automobiles, it think the rpm is 1800 or so.
Also check out features, some motor supliers don't include goodies like oil coolers, dual filtration on the carb motors but do on the F.I. modles. I've had them both and I would go with F.I. IMHO.

[boater]

hey northwest, is there any significant difrence in the power of your boat and the one with the carb, thanks..

[nwjetboat]

Not in top end, exactly the same. Mine is a little more snappy in throttle response, especially off idle.

[Deleted User]

Sal, a 74 Pinto. Interesting. We had a '75 Pinto wagon and luckly sold the thing before the public became aware that is was actually a large Presto Log on wheels. It even had the fake wood sides. If I coudn't have sold it after the news came out about them bursting on fire in rear end accidents, I would have put big hot rod type flame decals along the wood siding. Maybe driven it around some Ford dealerships until they bought it from me http://www.ifish.net/forum/images/graemlins/grin.gif . - RT

[Salmonator]

LOL RT, mine was actually pretty cool for what it was. Root beer brown, three coats of wax and slotted aluminum mags. The old Kraco had Hagar and Ratt blarin' out of the 6X9's It had the bigger 4 popper (2.4 I believe?) and I could acutally get it to 105 on a speedo that went to 110. We drove that car to bakersfield after graduation and at one point on I-5 the motor died. After it cooled awhile we inspected the motor and found that we had run it completely out of water AND oil. Two hours later we were able to replace both and actually fired her back up and made the trip down to Bakersfield and got another 3 or 4 thousand miles out of her before the head gasket finally blew. Memories.....

[onstep]

The advantages of fuel injection in the marine environment are the turn key start and smooth running performance. You also have the benefit of more horsepower. However, they burn more fuel than a carb motor according to tests done by manufactures. I think the benefit to the carb is the simplicity of the design and the cost of repair. The carb motors can be tempermental in starting, no question in that regard. For the money though I would go with the carb.

[Pilar]

Just a question. What does the CG approved spark arrestor look like on the FI and TBI models? I have never run either and only know about the DEVO hat, filter looking gizmo they put on the carburetor fed motors.

BTW the best mod on an older engine is the electronic ignition. Way better than points, more power, better starting, better reliability. Mallory makes one for almost any I/O motor on a boat.

The bend is your friend!

[nwjetboat]

The flame arrestors come in a couple of styles. I have seen the multi-layer screen volvo-penta uses, but marine power uses a K&N that is CG approved. Looks just like a K&N cone style filter.
Anything I read on carb vs. Inj. for same motor is that at cruise, the Inj motor gets slightly better mileage, at WOT they numbers are nearly identical.
By the way, the guy I know with a Carb 454 has a Flowscan on the fuel line. VERY accurate gauge, if it says he burned 45 gals, then the fill up will be between 44-46. It has a totalizer and current fuel burned. At WOT the 454 burns 28 gals an hour. These flowscans are not available for Inj. motors because the unused fuel goes back into the tank. They can't seem to make it work.

[Pilar]

Dang! My little 4 cyl 181 CID Iron Duke Chevy burns 7.5 gallons an hour at 4400 rpm WOT, 2600lb boat going 33mph. Now why were you wanting to go just a little faster?
It hardly seems worth it.

The sled heads really suck it down!!!!!!!!

The bend is your friend!

[boater]

anuone seen the new 496ci 8.1 450 horse engine in a sled yet ??

[Beer Waggin]

The new 496 has 425hp and the option is 475hp. Wow! I saw the 425hp model in a new 22 footer, I need not mention the model cause you know I'd never look at the competition. I'd like to drive one, but I know what I would do if I did and my checkbook wouldn't like it! Besides that, I think I'd rather tear the bottom up on my 20 footer learning the rivers before I step up.