26 Daytona 1000HP, IMCO Ext Box..going with a IMCO SCX..but what lower & gear ratio?

[mgh]

Going to be going with the IMCO SCX Upper, but not sure what lower and gear ratio? Boat dyno'd at 1000hp/1000tq

IMCO Neutral Extension Box

1) IMCO SCX Upper, SCX Lower (heard SCX Lower scrubs speed, maybe changes boat handling?)

2) IMCO SCX Upper, SC Lower (basically same setup as a BMAX...larger upper gear set, XR lower gear set)...

3) IMCO SCX Upper, Dual Downshaft Lower

Going to do the 1 7/16 propshaft upgrade...unless anyone says not too?

Thanks for all the help

 

[Racey]

IMCO will probably give you some solid advice if you call and talk with them. They have excellent customer service.

 

[HALLETT BOY]

I’m guessing SCX upper with new dual shaft lower

 

[Water rod]

The set-up is huge. If your gonna run an SCX lower you will need to surface it. If not the boat will slow down. Where is your X dimension? The SCX upper with downshaft lower is a good solid option. Stay away from the SC lower. They don't take 1000+ hp and torque well. Gear ratio generally want 1.34 with bigger HP so you don't run out of props.

 

[mgh]

IMCO will probably give you some solid advice if you call and talk with them. They have excellent customer service.

Spoke to fred @ imco the other day , said scx/sc combo.Going to call again tomorrow to double check before ordering. Would like to find someone who has a combo they are happy with

 

[mgh]

The set-up is huge. If your gonna run an SCX lower you will need to surface it. If not the boat will slow down. Where is your X dimension? The SCX upper with downshaft lower is a good solid option. Stay away from the SC lower. They don't take 1000+ hp and torque well. Gear ratio generally want 1.34 with bigger HP so you don't run out of props.

right now my Bmax is 1/2 inch @ prop shaft center lower than hull

 

[zx14]

I have about 40 hours on Sc lower scx upper, about a inch above the sponsons. ITS standoff.

 

[mgh]

I have about 40 hours on Sc lower scx upper, about a inch above the sponsons. ITS standoff.

what hp, gear ratio, lower is -2? Prop? Thnx

 

[ToMorrow44]

If you haven’t already, ask this question on the Eliminator Boat Owners Facebook group. There’s a wealth of info there

 

[zx14]

what hp, gear ratio, lower is -2? Prop? Thnx

1.34 hp close to yours, heavily worked BBlades 28” bravo, at 29” now. Gets me to 6300 rpm. With the XR, I’d run my 32” bravo, BBlades brought down to 31”. The XR was a inch below. The scx upper did take some mph, even with the higher X.

 

[Blackmagic94]

Merc #6 or bust

 

[mgh]

1.34 hp close to yours, heavily worked BBlades 28” bravo, at 29” now. Gets me to 6300 rpm. With the XR, I’d run my 32” bravo, BBlades brought down to 31”. The XR was a inch below. The scx upper did take some mph, even with the higher X.

Curious if anyone is running the 1.24 imco ratio overall?

seems like majority is 1.34

 

[mgh]

Merc #6 or bust

on the next boat for sure

 

[Boat 405]

1.34 gear ratio. Scx upper sc lower.

 

[mgh]

1.34 gear ratio. Scx upper sc lower.

is that what your running? What prop, hp, and mph/slip do you see..thanks

 

[ONE-A-DAY]

1.34, with 975 hp i ran out of props with a 1.50

 

[Boat 405]

is that what your running? What prop, hp, and mph/slip do you see..thanks

No. I’m running 860 hp. 800 ft lbs normally aspirated 582. 1.5 ratio scx upper. Sc lower -2. Stock 30 p bravo spins 6300 rpm. 109 mph in a 25 daytona. Imco extension neutral box.
You’ll be in the upper teens with 1000 hp/ft lbs. tried the DD. Boat didn’t like it. Went back to the SC. I’m assuming blown deal. 1.34 ratio with a 30 or 32 will probably be your go to

 

[mgh]

1.34, with 975 hp i ran out of props with a 1.50

what is your setup?

 

[mgh]

No. I’m running 860 hp. 800 ft lbs normally aspirated 582. 1.5 ratio scx upper. Sc lower -2. Stock 30 p bravo spins 6300 rpm. 109 mph in a 25 daytona. Imco extension neutral box.
You’ll be in the upper teens with 1000 hp/ft lbs. tried the DD. Boat didn’t like it. Went back to the SC. I’m assuming blown deal. 1.34 ratio with a 30 or 32 will probably be your go to

yes, blown 565, 14-71 blower tuned for 93 octane ...thinking 1.34 is what I’m leaning towards. the 30p

assume the 1 7/16 prop shaft? Any reason not to do this and go 1 1/4 prop shaft? Thanks

 

[ONE-A-DAY]

what is your setup?

02 Daytona 26 ICC, 32 in winter 30 in summer, 900 hp, max machine xr, -2 imco, best was 117 on Christmas day

 

[mgh]

02 Daytona 26 ICC, 32 in winter 30 in summer, 900 hp, max machine xr, -2 imco, best was 117 on Christmas day

1.5 gear ratio?

 

[She's Mine]

I'm running the SCX upper and SCX blueprinted lower. I went with dependability over speed. Yes, at times I wish I had the SC lower but I've been running this setup for a few years without issue. 1100HP 1.34 gears and a worked Bravo 35p. To be honest it all depends on what you want to do. I know plenty of people that run the SCX/ SC setup and have broken and I know people that run the same setup and it holds together. Just depends on how hard you are on the throttle.

 

[mgh]

I'm running the SCX upper and SCX blueprinted lower. I went with dependability over speed. Yes, at times I wish I had the SC lower but I've been running this setup for a few years without issue. 1100HP 1.34 gears and a worked Bravo 35p. To be honest it all depends on what you want to do. I know plenty of people that run the SCX/ SC setup and have broken and I know people that run the same setup and it holds together. Just depends on how hard you are on the throttle.

i would say i am a sensible driver, has anyone used the 1.25 gear ratio and had success?

 

[ONE-A-DAY]

1.5 gear ratio?

1.35, with the 1.50 we were hitting the rev limiter with a 34 in the winter time

 

[mgh]

1.35, with the 1.50 we were hitting the rev limiter with a 34 in the winter time

i see the 1.25 gear ratio as an option? would this help...what would the trade off be? i see imco offers 1.25, 1.34, 1.5

 

[ONE-A-DAY]

i see the 1.25 gear ratio as an option? would this help...what would the trade off be? i see imco offers 1.25, 1.34, 1.5

the 1.34 allowed us to go down a prop size, i considered things resolved

 

[mgh]

the 1.34 allowed us to go down a prop size, i considered things resolved

Going to get 1.34

 

[Boat 405]

yes, blown 565, 14-71 blower tuned for 93 octane ...thinking 1.34 is what I’m leaning towards. the 30p

assume the 1 7/16 prop shaft? Any reason not to do this and go 1 1/4 prop shaft? Thanks

I’d get the 1 7/16 shaft. Opens up availability to props