Run_em_hard

5,200 rpm.

scarabman

iTrader: (1)

Not trying to be an A$$, but you realize that isnt feasible? You would have to have only 6% slip to hit 80 much less 5% to hit 81. As a reference, a 33 AVS which is essentiallty the same weight as your boat, with HP 500s will only run 81-82. It will have a significantly better hull efficiency, so you see where I am going with this?

dandercam1

iTrader: (1)

Acording to Wellcraft 1992 Scarab 31 is 7300 lbs dry

2000 Scarab 33 AVS is 8400 lbs dry

1100 lbs makes a BIG difference possibly could offset the difference in the AVS stepped hull, but I would think 6% slip is hard to believe.

I have heard of 33 AVS's hitting 80 with 502 mag's IMCO exhaust and labbed props

Rookie

iTrader: (4)

It is 14% with 1.36 gears.

scarabman

iTrader: (1)

True, but under the assumption that the boat is basically stock, which I really dont know, it is highly unlikely he would have 1.36 gears with HP500s. I think it also arguable that a stock, again assuming, HP500 could turn a 26 pitch prop with a 1.36 ratio to 5200 rpm?

scarabman

iTrader: (1)

As I recall, the 31 Thunders were mid to late 90s boats, which puts their weight much closer to 8000 lbs and close to the AVS. If you figure the AVS is 8-10% more efficient, it at least gives you a benchmark. Regardless, 5 & 6% slip are unattainable in a heavy Bravo driven v-bottom.

As for a 502 powered 33 AVS hitting 80, maybe hitting on rare occassion as a split second best, but running, no. I have owned a 502 powered boat with SM exhaust and running labbed 28 props and the boat would run around 78 fairly consistently. I owned an HP500 33 AVS and the boat would run a consistent 81 with labbed 30s. I now own a Volvo 600 33 AVS and it is a whole different animal

dandercam1

iTrader: (1)

Scarabman I agree with you 100% the 31's grew from 7300 lbs in 1990 to 7900 lbs 1995-98 wich probably explains the range of speeds in what is essentially the same hull but like you are saying its the prop pitch and slip numbers that are confusing me.

Both run em hard at 81 with 26p bravo's and indysupra at 86-87 with 28p bravo's are getting amazing speed numbers with those props. I was on the same page thinking 1.36 gear. I also noticed there slip numbers are about the same.

I have read that the 33 AVS with the 600 DPX's is one of the most impressive setups scarab ever built.

indysupra

iTrader: (3)

I am running 1.50's. Are all of the 31's kevlar?

MILD THUNDER

iTrader: (3)

Keep in mind when doing prop slip calculations with a bravo 4 blade, you cant use their stamped pitch number. They may be stamped 26" of pitch, but actually measure out to about 25.2''. They're almost a full inch of pitch less than stamped.


Either way, 82mph with 465HP per side in a old 31 Scarab, is tough to believe. My buddies late 80's 34 scarab is lucky to see 65mph with that power. I cant see the 31 being 17mph faster and only 3ft shorter. My buddy has a 2000 33AVS, turns 28p bravos. Its about a 80mph boat. A pad bottom 33/35 Fountain of that era with 500's wouldn't hit 80.

Either way the 31 Excel's are cool. Always loved the early 90's ones, they had awesome cabins! Pretty pimped out, then later they kinda cheapened the cabins up imo.

MILD THUNDER

iTrader: (3)

Those 33AVS 600/Volvo package always intrigued me. I heard they ran fantastic!