Which do you think would get better gas mileage?

[anon1]

Hello,

Either a 4.3l V-6 running near full throttle at about 40-45mph

or

the 350magnum V-8 running near 2/3 throttle (top speed 65) at same speed and same type boat.

Thanks.

 

[aerwin]

Re: Which do you think would get better gas mileage?

the v-8 will be better, althoght most of us dont care about the milage, its about fun. the v-6 at full throttle will pound its little heart out and you will be replacing it sooner. which in turn will cost a whole lot more than a few mesily gallons of gas you might save with it. get the 350 v-8 and enjoy it. if your worried about a few gallons then boating probably isn't for you. if its about the "earth thing" then get a canoe

 

[aerwin]

Re: Which do you think would get better gas mileage?

by the way Welcome to I-boats. I wasnt trying to be sarcastic or rude. Boating is about fun, enjoying life, a get away from life and most of us put lots of money in it to be able to do that. but you would be happier with more power. nothing worse than an underpowerd boat. you have power when you need it. the engine works less and you have better re-sale

 

[Mischief Managed]

Re: Which do you think would get better gas mileage?

To push the same boat at the same speed, they'll both use almost exactly the same amount of fuel. The V6 will have the advantage of slightly less pumping losses and less weight, but at WOT, will be operating well beyond it's peak volumetric efficiency and igntion advance RPM, so there will be some wasted energy going out the exhaust. The V8 will be closer to it's peak volumetric efficiency RPM (guessing 3500 RPM or so) and will convert more heat into power for a given amount of fuel by not operting at WOT.

 

[Mark42]

Re: Which do you think would get better gas mileage?

How far do you travel that you need to go that fast?

 

[QC]

Re: Which do you think would get better gas mileage?

What MM said ^^^^

I would add that the 4.3 might do slightly better due to weight benefits.

Also, I don't believe that the two examples you give would be 20 MPH apart at WOT, in exactly the same conditions, same boat. I could believe 10 MPH difference unless the 4.3 is a carbed 170 and the Mag is an MPI 300 . . . Currently they are 220 bhp and 300 bhp respectively. Tell us more about what the deal is, or maybe you have some good data to share . . . Hope so

 

[cmcpherson]

Re: Which do you think would get better gas mileage?

What MM said ^^^^

I would add that the 4.3 might do slightly better due to weight benefits.

Also, I don't believe that the two examples you give would be 20 MPH apart at WOT, in exactly the same conditions, same boat. I could believe 10 MPH difference unless the 4.3 is a carbed 170 and the Mag is an MPI 300 . . . Currently they are 220 bhp and 300 bhp respectively. Tell us more about what the deal is, or maybe you have some good data to share . . . Hope so

Good point, what is the boat that is getting 65 MPH from the 350, because I obviously have the wrong one!

 

[anon1]

Re: Which do you think would get better gas mileage?

What MM said ^^^^

I would add that the 4.3 might do slightly better due to weight benefits.

Also, I don't believe that the two examples you give would be 20 MPH apart at WOT, in exactly the same conditions, same boat. I could believe 10 MPH difference unless the 4.3 is a carbed 170 and the Mag is an MPI 300 . . . Currently they are 220 bhp and 300 bhp respectively. Tell us more about what the deal is, or maybe you have some good data to share . . . Hope so

I appreciate the replies so far.

I'm looking at used Baja cuddy cabins.

Boat A: Baja 216DVX w/ 4.3l V-6, topped out at about 45, NADA says weighs 2916

Boat B: Baja Force 216 w/ 350Mag V-8, topped out at about 63-65, NADA says weighs 2910

I will be using it for weekend long excursions where some speed will be nice to get were we're going but don't see going 60-65 often at all. But I don't want to be going 40-45 and staying at the top end of a V-6.

 

[cmcpherson]

Re: Which do you think would get better gas mileage?

According to the speedo?

 

[anon1]

Re: Which do you think would get better gas mileage?

Yes, by speedo not gps.

I think that Boat A was kind of slow and I could tell that the engine was a little tired, so maybe it was unusually slow when you consider that I'm aslo looking at a

Boat C: Baja Hotshot w/ 4.3l V-6. It is same hull and design as the 216's but it is lighter as some of the "frills" are left off. NADA says weight of 2,400 and I've had it to 51-53, by speedo.

 

[cmcpherson]

Re: Which do you think would get better gas mileage?

Yes, by speedo not gps.

I think that Boat A was kind of slow and I could tell that the engine was a little tired, so maybe it was unusually slow when you consider that I'm aslo looking at a

Boat C: Baja Hotshot w/ 4.3l V-6. It is same hull and design as the 216's but it is lighter as some of the "frills" are left off. NADA says weight of 2,400 and I've had it to 51-53, by speedo.

Yep, one time I had my boat doing 80 on the Speedo, the fuel gauge said it was completely out of fuel too! Don't believe the advertising, it is never right!

 

[bekosh]

Re: Which do you think would get better gas mileage?

Good point, what is the boat that is getting 65 MPH from the 350, because I obviously have the wrong one!

How much do you want to mod the engine & drive??
http://www.rlcpe.com/images/projects/tripple_digits/project_trippledigits.html
These guys hit 70mph with a 1989 Sting Ray Maxxim II SVS-220 and a stock 350/Alpha. Then hit 91mph with it using a SBC stroked & bored to a 434cid.

How fast do you want to go? How much money do you have?

 

[John_S]

Re: Which do you think would get better gas mileage?

A 21' boat, go with a V8. With a V6 you will be thinking of upgrading by the end of your first season.

 

[QC]

Re: Which do you think would get better gas mileage?

Cool stuff bekosh. I wonder why there was no speed number from his new HD drive . . . I can't help but poke fun at the chiMe walk (maybe bells go off in his head) and his misunerstanding of X dimension, but OK, very good info . . .

 

[Mischief Managed]

Re: Which do you think would get better gas mileage?

Cool stuff bekosh. I wonder why there was no speed number from his new HD drive . . . I can't help but poke fun at the chiMe walk (maybe bells go off in his head) and his misunerstanding of X dimension, but OK, very good info . . .

That was cool.

Made up for any mistakes (IMO) by successfully cutting up the Alpha, welding it back together and getting it to work. Impressed me.

The 61 MPH with 270 HP and 91 MPH with 637 HP are almost exactly what one would expect for a given amount of drag. With the reduced drag, it should easily top 100 with that much power on hand. I bet it would top 120 with a surface drive...

 

[QC]

Re: Which do you think would get better gas mileage?

Made up for any mistakes (IMO) by successfully cutting up the Alpha, welding it back together and getting it to work. Impressed me.

I totally agree!! Don't show this to kyle in I/O ^^^^ Out the torch would come . . .

 

[erikgreen]

Re: Which do you think would get better gas mileage?

Did anyone else think that his heavily modified alpha drive looked a lot like a bravo?

Erik

 

[bekosh]

Re: Which do you think would get better gas mileage?

Over on the Speedwake board, he was claiming 98mph, but was having handling issues.
I can't imagine 100mph in a 22ft boat. I'll be happy if I can get mine up over 60mph. I need a higher pitch prop. 21p gives a great hole shot, but runs out of steam at 58mph.

 

[John_S]

Re: Which do you think would get better gas mileage?

My favorite:
For equal comparison in all of our test will be conducted using standard 89 octane pump gas, with a 1/4 tank (about 10.5 gallons) using champion spark plugs gaped at .035


I couldn't find the test where they replaced the ACs or NGKs.

Overall, that hull must be quick and light. The weight posted is 500lb lighter than my 20fter. A very good baseline mph number. 70mph with a SBC, probably pushing close to 350hp. Basicly 100hp and 10mph.

Bekosh, I'm with you, don't think I will quite hit 60. There is always next season and a few tweaks.