The Right Prop?

[Span 24]

Re: The Right Prop?

Yes and his v6 is out performing the v8 coupled with 600lbs or more weight..Opp's drop a hun for the 6..

TG: I don't know about 'outperforming' the test vehicle, perhaps. But I do know these facts:

The boat is an 03 Starcraft Aurora 2000
The engine is an 02 Volvo-Penta 4.3GL
The prop is a Volvo-Penta 15x17 (aluminum)
My test was with 45(+) gallons of 89 octane 10% ethanol fuel (I actually overfilled the fuel tank the morning of the test) and the fuel guage read 'full'
I had myself and 4 passengers onboard (averaging 210Lbs each)
I was carrying an extra battery (not listed on the test vehicle), a complete toolkit, spare prop, required USCG gear (including ~three~ extinguishers), ropes, anchor, and ~three~ tubes
The 38MPH was shown on both the Speedo ~and~ the GPS
The throttle was wide opened
The boat was on plane when I recorded the data

What I cannot confirm is the tach reading. I can tell you that I verified that the tach was set for 6 cylinder engine. I will try to get ahold of a test tach to verify these readings this weekend. If I ~am~ able to confirm the tach readings how might we explain my boat outperforming the test vehicle?

Thanx for your interest in my question!

Michael

 

[MikDee]

Re: The Right Prop?

I know from experience, a 4bbl Vortec headed 4.3 V6 180-220hp, is very close to, if not at times exceeding a stock 4bbl 5.0 V8 without Vortec heads 180-230hp.

Years ago a Vortec headed 4.3V6 200hp Astrovan, gave my 88' Monte Carlo with the HO Non-Vortec 5.0 180hp motor, a good run,,, I think the only advantage I had was the 3:73 rear.

You hafta remember both engines have the same stroke, but the 4.3 has bigger (5.7) 4" pistons, as opposed to the (5.0's) 3-3/4" pistons and has less internal friction due to 2 less cylinders, so it's torquey, & peppy!

Of course the Vortec heads on the new 5.0 4bbl engines help it develop 260hp nowadays, but only 230hp in 2bbl form.

 

[Tail_Gunner]

Re: The Right Prop?

http://www.go-fast.com/Prop_Slip_Calculator.htm

Enter your numbers and you will also be confused..Your gear ratio is posted on the drive, it would be intresting to know that value.Since you have used gps to determine the speed little is left other than the tach or maybe the wrong pitch...​