Trouble with SCX -4 on 27 Daytona
 

I am currently working on a 2006 Daytona 27, which used to run 118mph @6000rpm vary consistently with driver, after breaking multiple vertical shafts on bravo units, my friend opted to buy and have a new Imco SCX-4 installed. He was told that the SCX -4 would be @ the correct prop shaft height to run a cleaver style surface piercing prop from Herring, so with the drive also purchased a 29p 18r 5blade 17inch Herring wheel to run with this setup . He had run some herring props before with no substantial results. His original setup was a Teauge platinum drive (AKA bravo) with a imco -2 lower /w/ 1:36 final drive and a bravo 32p lh 15 1/4 4 blade . After switching from the bravo to the imco SCX-4 we could never get the boat over 99 mph with the Herring prop (surface piercing) . After doing a little research some people said that the prop shaft height was to low and at the time was even with the bottom of both sponsons. In order to obtain original speed we decided to have a 1- 7/16" shaft installed into the SCX-4 to accommodate the old 32p lh 15 1/4 bravo prop. Well that didn't work the engine spun up to 6000 rpm and top speed was 99mph . Your'e gonna love this , then we put a 1-1/2 inch spacer on the lower and no BUENO ! same thing 99MPH 6000rpm. PLEEEEASE HHHHEEEELLLLPPPP MMMMEEE!!!!!!!!!!!!!!!!!

Were all of these speeds on a GPS ?

How much higher is the SCX-4 in conjunction with the outside sponsons now verses when you had the -2" imco SC on there.

maybe gear ratio is different ?

I would think this would make a sweet setup on a 26 Daytona. I does sound like it could be the gear ratio.

The prop shaft height with the SC lower is 2 inches below the sponsons and the SCX-4 is two inches (shorter) even with bottom edge of sponsons.

I verified with IMCO with the serial number that it has 1.36 final drive in the SCX-4 which was the same ratio as the Bravo drive he ran previously

Not sure if this helps. I went from a Bravo XR LWP to an Imco Xtreme SC (standard length to standard length) and lost 4 mph. 27 Daytona.

The SC lower was set at 2" inches below the outside sponsons and the boat ran 118, the SCX-4 was installed and it raised the lower even with the outside sponsons (less lower in water less drag) and the boat slowed down 18 mph. You did not mention how the boat handled with the SCX-4, I would think the boat would have felt a little looser at speed on the water. I know 26Redline on the Hotboat forums has one on his RPM26 and loves it. I would talk to Bob Leach at Eliminator.

I think the surface type cleavers like to run a couple inches above the bottom so yes it might be too deep. But at the same time, thats probably too high for the 32 Bravo since thats a 26% slip at 99mph 6000rpm. Actually, I would check out the speedo, running 99mph in 3 different configurations sounds weird. Are you sure that is correct? If not, get a gps app on your phone (free) and check that.

Dirt173,

Have you made any progress getting the speed back with the new setup, trying to understand why this setup would loose so much speed.

Send me a PM with your phone number.

Sonny

Dont feel like the lone ranger in all this.. I have a 26 Daytona with 525 and a stage two Whipple. About 850hp. I'm having same issue. I bought a scx with new scx lower after blowing xr upper and it slowed me down 20 mph. With drive heights the same as before running 110mph with bravo xr and sc platinum lower 1.34 gearing. I lost 20 mph with scx drive. My slip was only 10% with xr and sc lower and bravo prop. Now its 24%. I was told to take 2" spacer out and boat got real loose. Prop shaft center line is 2" above sponsons now. Im waiting on Teague to tell me what to do next. Just purchased all of this through Teague. PS i have two gps speedos. One on nav screen and the other is boat gps speedo.

Hi would you like to sell the Scx No 6 shaft?

anything ever come of this? I gained 10 mph with a 2' imco going from 1'' below to 1'' above sponsons

Where are you measuring on the bottom of the hull? I was told to measure about 12 inches forward of the transom. This is the lowest point. I am running a -3 IMCO on my 26 and the prop shaft is about 1 inch higher than that lowest point. I had to create more negative trim to get the boat on plane with the 28 Bravo 4 blade. The boat likes this prop as it handles well and has low slip numbers. I cut the bell off of the back of the prop and then had a hard time getting on plane but it settled the transom and the boat liked to fly with little effort.
I bought an IMCO neutral extension box this winter and intend to install it at least 1/2 higher than the drive is mounted now.

I just bought a scx4 for my 26 daytona. Wish I could have found more info about this before I pulled the trigger.

I meant 10mph. I am measuring off the bottom.of the sponsons. Lowest point before the notch

Round one with scx4 did not work very good at all. Went from a great driving boat to a big pyle of ****. Trying another prop tomorrow!!!!!!!!!

How has this turned out, I need to replace the xr on my 26 Daytona

I have SCX UPPERS with 1400 lowers.

1) the helmet is longer, soooo the prop shaft is farther back. This changes setup

2)the front of part of my prop is blocked by the fat housing.

3)same gear from xr's to scx. I lost about 14 mph.

4)I went down in pitch to 33's but up one blade.
Lost 8 mph

I think no matter what it's going to take more hp to turn the scx.

Hi Dirt173, did you ever get the set up right with the SCX-4 and gain any top end speed back?
The few guys I know with 26', & 27' Daytona's who went with the SCX-4 have all had difficulty getting top end speed back with the 1400 lower using bravo props.
I have not heard of anybody having great success surfacing the SCX-4 on a 27' Daytona bottom. If anybody has, please fill the rest of us in on the secret.
If you are still having trouble, I would ask IMCO to get you in touch with Brad at E-Ticket boats. From what I was told by Eliminator, he re-designed the 1400 lower for IMCO. I also heard he has blue printed some lowers for other people and it has helped re-gain some top end speed.

Hope this helps,

Bo

My 1400's were blue printed from imco. The bullet will cut your finger. I think most of the speed loss is just the huge weight. I had to use a come along to lift them into place. I can pull a Xr/imco combo by myself.

CLA,
I am running what IMCO calls the SCX-3, I attached some photo's below. My drive looks identical to the SCX-4, but its not as short for lack of a better explanation. The standard SCX does not allow enough clearence to run a minus 3" lower unit, which I need. My new SCX-3 upper is way heavier than my old XR upper. I did not go with the 1400 lower for the exact reason of this thread, and I also wanted to keep my IMCO SC -3 short lowers due to X-deminsion/prop shaft height. The 1400 lower appears to have slowed most of the boats they have been placed on. I know the RPM boats really like the SCX-4 with 1400 lower in a surfacing application, but not 27' Eliminator Daytona's as far as I've heard. I have two -3 short SC lowers so I can switch in between rebuilds and incase one breaks. Sounds like you have done your research, and I agree with you that the 1400 lowers are just plane heavier. The gears in the upper of an SCX are massive compared to XR (bravo) style gears. I know the 1400 lower gears are the same way, massive in comparison. It only makes sense that it would take more HP to turn the bigger gears and drag a bigger lower unit along. I know E-ticket boats shaves down the cases and does some other stuff to create less drag, just like IMCO probably did to your lowers.

Cheers,
Bo

[ATTACH=CONFIG]547168[/ATTACH][ATTACH=CONFIG]547169[/ATTACH]

El Guapo, Love your boat,.. Just so I understand your current SCX setup, you have a regular SCX-4 Upper so to speak and are using a -3 SC imco lower making it a SCX-3? If so how much higher is your lower now verses your old setup with the B1XR and SC-3. And how does you boat perform with the new setup verses the old. I have a DCB M26 and I am just curious.

Thank you for the info you have aready posted.

Hi J.P.
Yes, my upper has a curved cavitation plate like the SCX4, only I am not sure mine curves up as much in a vertical direction as the SCX4. I need to ask IMCO.
I would have purchased the SCX4, but the SCX4 bolt pattern only allows for the 1400 lower, as far as I was told by IMCO.
I was using an XR upper with a -3SC lower and had to add a 1/2" spacer to get boat to plane out. With this set up, my prop shaft height was about level with the bottom of the out side sponsons. After installing the SCX3 with the -3 lower, I am 1/2" above the bottom of the outside sponsons. I think I can explain why I am able to plane out with a 1/2" higher x-demension now, as opposed to before.
The prop shaft is now further back when compared to the XR with SC Lower by about 3/4", this puts the prop deeper in the water during take off. The SCX upper weighs more than my XR upper too. With the extra weight, and prop further back, I am deeper in the water than before and I don't need a spacer.
The boat really likes the new drive. It actually handles better, and more of the boat is out of the water at higher speeds then compmared to the XR. This may be due to the 1/2" rise in prop shaft height, but I think the curved cavatation plate has helped too, feels like it carries the nose of the boat better. The boat seems to pack air quicker, and feels more responsive to trim. Handeling in turns did not chage at all, boat turns awesome.
The boat now takes more RPM's to plane out. With the XR/SC set-up, the boat would roll over at 2,800 RPM. With the new SCX3/SC set up, the boat will not roll over unless you hit 3,800 RPM. The prop never blows out, it just is not slipping untill you reach enough RPM's to create slip and get on plane. I am not sure if I lost any top end speed. We sold the motor that was in the boat after the Monster Bash poker run. We orderd a Teague Custom Marine 1025 last week. Unfortunatly, I will never know if I lost any top end speed, or maybe gained speed with the new SCX3.
Hope some of this informatin answered your questions.

Cheers,
Bo

El Guapo,
That is good info that with the drive 3/4" further back due to the helmet length you are able to run the lower higher due to the boat setting lower in the water at take off. That little bit makes difference I guess. Thanks for the clarification on the SCX-3 and good luck with your new motor.

Joel

My boat gets on plane easier also.

Guapo you own "The Sizzle"? I saw your boat at MB. I had the 36 coupe " Paper Chaser"

The Sizzle ...
[ATTACH=CONFIG]547489[/ATTACH]

Paper Chaser ...
[ATTACH=CONFIG]547496[/ATTACH]

Yes that is my boat, thanks for posting picks Gary :-) I love your boat, simply bad ass. I think we spoke in passing in the cove. I bet you were glad to have that cock pit cover when it was raining on us during the poker run. Hope to see you guys at D.S.

Cheers,

Bo

Just saw this thread. My RPM 26 came with the SCX-4 and is still on it. It ran 123 mph with a 760hp 598. A 35 pitch Herring #6 spline is the only prop I have used. The boat was pretty well dialed in from Steve at RPM.

I have since added a 4.5L Whipple. It can now run about 130, but I usually back off around 128. I did have Brad at E ticket blueprint the lower. I think he originally solved IMCO's problem with this drive and they have now incorporated these changes into their designs.

The main advantage to this drive, IMHO, is the strength to handle 1000+HP which the Bravo cannot. I also think the Bravo gearcase is faster than even the SCX-4 with a surface drive prop.

It was the potential to support high HP that convinced me to be the first RPM build with the SCX-4. It's great to go boating and not have to worry about blowing an outdrive.

Since you have a -3, your issues may be different. You could contact E Ticket in havasua, since they were the first to tame the -4 version. Other than that. call Junior at IMCO. He is pretty much running it as he dad ages.

Hi bultmand

Thanks for the info you posted about your RPM and SCX-4 surface set up. I spoke to another Gentelman that has a 26' RPM Steve built with the SCX-4, surfaced, and his boat is very fast like yours. He said he did some modifications to the lower unit to eliminate the tourque steer and he is very happy with the drive. Do you, or did you ever experience any torque steer and if so, what did you do to correct it? I have seen some really neat viedos of the RMP boats done by Steve, R.I.P, and they all seem to work very well with the SCX-4 surface application.
I heard Brad at E Ticket is the man, I also heard how he fixed the SCX lower by redesigning the leading edge for IMCO.

I am still in search of someone who has successfully surfaced the SCX-4 on a 27' Eliminator Speedster like mine. Talked to two guys who tried with 26' Eliminator Daytona's and they both said it was not worth it.

Happy New Year!

think its the shape of the drive...had a friend with a 36 specre switch to these and also lost over 10 mph

Yea crazy crazy speed kill!!! We spend so so much money to go fast! Just to spent a ton to lose like 10 MPH i will never do it!!! Been watching this drive and post with the same out come over and over it crazy!! Just so happy my Drive has been perfect for 5 years!! But i dont boat in big water....This day and age i just cant get over why this is so hard..... Good luck guys!!

Skydog

Skydog, you ended up keeping it and not selling.

Yea sure did man!!:party-smiley-048::party-smiley-048: I made it threw the big D!! I just love it so much man!!!! How you been? Great to hear from you.

I plan on doing the SCX -3 upper with the -3 IMCO lower.

I'm good, took my DCB M26 to an engine builder out of Oklahoma City named Keith Scroggins. He built the engine back in 2000 when the boat was built new for the original owner and shipped it to DCB and they installed it. To my knowledge it has never been freshened up so it was time. Hoping to get it back in the next week or two, this is the time of year I like to boat. The engine is similar to yours only a roots 14-71 and around 900hp.

Sweet what drive is on it?

So far I have been happy with the SCX-3 with -3 SC lower. It was usually my XR upper that broke or had chipped/pitted gears. I have only had trouble with one SC lower. Keep us posted on your results and speed changes.

Cheers