1978 85hp fuel consumption

[iwombat]

Re: 1978 85hp fuel consumption

FWIW I think the seller just didn't quite understand the question, and averaged out fuel over a day's usage instead of estimating consumption at WOT. At least, that's what we seem to be arriving at.

 

[Texasmark]

Re: 1978 85hp fuel consumption

Gotta get back in one more time and I'm gone.

Silvertip.

I hear you on the hull and lower unit designs being improved and agree that it muddies the water trying to figure the engine burn rate.

But I just can't buy what you said about consumption being pretty much equal. I know that you have said it several times on the site. You just can't feed me that cookie that says that all the technology we have experienced since the early days bought you nothing when you compare apples to apples.

I have BTDT and even though I haven't been there with calibrated instruments, I can tell. You can get the feeling after so many outings in different rigs when there is a differerence. I explained that in my comments on the first reply.

If all the technology bought us nothing, why do engine mfgrs spend all that time and money in making new engines? Yeah I realize some of it is sales hype, to garnish more market share, but still.

Just take engine smoke on 2 cycles for example. Back in the '50's you couldn't see behind you for the cloud and today you can't even see it. When you would hammer out of the hole there would be this humoungus fog. Now you look back and if you didn't see the swirls in the wake where you started, you'd never know you were stopped. Obviously the fog is unburned fuel and that's consumption that isn't occurring now.

Nuf said. We're going to believe what we want to, facts or not. Just human nature. d

Mark

 

[Silvertip]

Re: 1978 85hp fuel consumption

Since everyone seems to be too lazy to go to Yamahas web site themselves, I'll did it for you. I own an Alumacraft Navigator 165CS and its powered by a carbed 75 HP Merc. I've given you my fuel flow rate numbers. 7.5 GPH @ wide open throttle and 5.0 GPH at 4000 - 4200. Write those down.

Yamaha tested the same boat with a 75 HP FOUR STROKE. WOT (5500 RPM) and that engine burned 7.7 gph. At 4000 - 4500 it burned 3.8 - 4.7 gph. The same boat in tiller form with a TWO STROKE 90 HP (no 75 HP test) burned 8.6 GPH at WOT (5500 RPM). If burned 5.0 - 5.7 GPH at 4000 - 4500 RPM. These are Yamaha numbers not mine. Now do you agree the 10% rule applies whether you have two-stroke or four-stroke at wide open throttle. And do you now agree that the fuel saving is in the mid range and lower RPM. A four stroke sips fuel at idle. What more do I need to do to prove this and to dispell all the hype about fuel savings claims. If you troll -- buy a four stroke. If you run consistantly at higher RPMs it makes nearly squat of a difference.

 

[Silvertip]

Re: 1978 85hp fuel consumption

Just re-read my post and Geez was I crabby this morning. Sorry folks. I had two computers going and was having a problem getting to an "ftp" site with some important stuff. Nothing personal here folks -- just firm in my position.

 

[iwombat]

Re: 1978 85hp fuel consumption

Sometimes posts just come across with an underlying tone that's not exactly intended. Happens to us all.

Hope your day is going better now.

 

[rickdb1boat]

Re: 1978 85hp fuel consumption

While I agree that GPH is the best way to calculate how long you can go before running out, there is still a big difference on how far you can get depending on the type of hull the motor is attached to. But yes, they would both use 10 GPH if both had 100 HP engines and distance was not a factor regardless of the engine.

 

[Texasmark]

Re: 1978 85hp fuel consumption

I lied. Gotta hit once more. No. No. No. on the direction this is heading. Today's 2 cycle is the perfected engine; not the engine of yesteryear that is the basis for my original position. I have to agree with Silvertip's facts cause they are facts, but I also believe that they are accurate and the reason is that the 2 cycle has come so far in the last 50 years.......as have the craft they power. Not the same critters.

Now, go and get yourself a early 4 cyl Sportifour or other cross flowed beast, built back in the early 4 cyl days (not prehistoric, early days....late '60's), or early 2 cyl days for that matter and run the test again. Guarantee you that you will not get the same results. Course if you did go prehistoric (old opposed 2 and 4 cyl.) then the answer would be worse.

Mark