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View Full Version : BBC- What RPM?



TuxedoPk
07-14-2004, 12:07 AM
When running WOT the 454 overbored to 468BBC in the GT is pushing about 5500 rpm. The speedo (non GPS) reads about 1% the tach from 4k-5500rmp.

Without putting my engine on a dyno, where should my peak torque and hp be on this engine? Gut tells me that I need a bigger prop and want to be running in the 4000s. What's my goal rpm for cruise and WOT?

Bill-Do you know how that other Vdrive GT was propped to be hitting 60?

smoothie
07-14-2004, 08:26 AM
Tux,buy a copy of DESKTOP DYNO or post your motor specs (cam,heads,CR)and have your hp and torx curves caluated to within 10% of a real dyno test.

MOP
07-14-2004, 08:51 AM
I know some will not agree but I do not like seeing them twisted over 5K, I would prop it down and let it live longer.

Phil

GKricheldorf
07-14-2004, 09:09 AM
When i repowered recently my 454's wot is said to be 4800 rpm. I have not yet gone wot - 4.5hrs left onn break in.

TuxedoPk
07-14-2004, 09:11 AM
Tux,buy a copy of DESKTOP DYNO or post your motor specs (cam,heads,CR)and have your hp and torx curves caluated to within 10% of a real dyno test.

Bought the boat last year and don't know this info. How important is having this/dyno test before buying a new prop? Is it worth the time/expense of having the engine pulled and dynoed just for this purpose?

smoothie
07-14-2004, 10:21 AM
Bought the boat last year and don't know this info. How important is having this/dyno test before buying a new prop? Is it worth the time/expense of having the engine pulled and dynoed just for this purpose?

It would be good to know but not a show stopper,Just go with a prop dealer thats willing to let you try before you buy,most will do it,just pay for the shipping.

BUIZILLA
07-14-2004, 12:18 PM
What size prop ya running now? :lobster:

TuxedoPk
07-14-2004, 02:18 PM
What size prop ya running now? :lobster:

I'll be damned if I can figure it out. There are 3 blades with markings

Blade 1 S
688
MENKENS

Blade 2 1215

Blade 3 P8 519