F8 DUO PROPS ON 8.1L 375HP????

[TG10]

I HAVE F7'S ON MY 2004 COBALT 250 RIGHT NOW BUT AM WANTING TO TRY AND GET MORE SPEED. DOES ANYONE KNOW IF I COULD GAIN ANYTHING WITH F8'S. AT 30MPH IT IS TURNING 2700 RPMS.

[JTinMO]

on my 2010 232 with the 8.1L Gi, I run F8s (came with them), but have no info on top end for you. I would guess you can run them just fine. your RPM and speed looks fine at 30MPH though. That big of a boat I would guess your top end is low 50MPH range though. Which is plenty fast.

[TG10]

It will run about 57 like it is now on GPS. I am just trying to get a little more to run with my buddies 242 with the 8.1 GXI.

[Big Block Power]

It's not about what rpm your running at 30. What are you running at WOT?
The gi I think max rom is 4600 rpm. It might actually run slower with a f8. Your hole shot will suffer. Ive ran f8 on my 8.1 gi and it just hit max rpm. Actually I wonder if you have a different ratio that you are not already running f8?

[TG10]

Honestly I don’t know what the ratio is but I do know that I am running F7s now

[Big Block Power]

Honestly I don’t know what the ratio is but I do know that I am running F7s now

Do you know your wot rom?
I think my 8.i gi ran 4600. My gxi f6 ran 5000 I run 30 and 3000 rpm now.

[TG10]

I will have to check next time I am up there never really payed much attention to it.

[Silverbullet555]

Get max RPM and max speed by GPS. It might be hard to run with your buddies 242. How do the weights compare.

To help you in your quest, remove all extra weight except for bikini clad models. It helps if the bikini clad model is your wife , otherwise your wife might get pissed when you leave her at the dock and take a bikini clad model.

On my 226 with an 8.1gi I run f9 st sea level and get into the low 60s. I've been running f9s at 2500 feet and get to about 59. I bought f7s to try, but haven't been out enough to give them a good shakedown.

Your max rpms with your current prop will help you determine if there is room to move either way.

[TG10]

Thanks. SB555. Next time I am out in it, I will check it out and let you know how it does.

[Driller]

I'm running the same props as factory which I think are F7s. WOT just shy of 4600 and GPS around 55-57 depending on the weather. 2011 242 w/ 8.1 Gi.

[TG10]

WOT my boat runs 4500 RPM. F7 props.

[cmattj]

WOT my boat runs 4500 RPM. F7 props.

Go shine those F7 props up!

That’s the correct prop . Any more ( F8) she won’t pull it. It will run hotter as result of strain.

[mdadgar]

To help you in your quest, remove all extra weight except for bikini clad models. It helps if the bikini clad model is your wife , otherwise your wife might get pissed when you leave her at the dock and take a bikini clad model.

This is the best advice I've seen on this board yet.

- Mark