BBC Classic Scarab Speed
10-24-2016, 04:59 AM
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BBC Classic Scarab Speed
Anybody out there running 500+ hp on a panther or panther 2 through TRS drives? What prop are you turning and what speed are you seeing?
10-28-2016, 12:49 AM
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Just another set up on a classic 30 foot scarab.
I have a 1979 Scarab 300. Running twin 540 BBC that dyno 625 HP @ 5600 RPM and 635 lbs. Im running the TRS drive and Borg-Warner tranny combo. That set up has proven to be a built-proof combo for 17 seasons. I have a very deep X-dimension (as set up by the factory way back when) where the prop shaft is about 8.5 inches below the bottom of the boat. I run a 28 pitch Bravo One 4 blade prop (props have been turned, so its more like a 27 pitch) to a best of 83 MPH on GPS. The deep X-dimension is a killer on top speed...
I have a 1979 Scarab 300. Running twin 540 BBC that dyno 625 HP @ 5600 RPM and 635 lbs. Im running the TRS drive and Borg-Warner tranny combo. That set up has proven to be a built-proof combo for 17 seasons. I have a very deep X-dimension (as set up by the factory way back when) where the prop shaft is about 8.5 inches below the bottom of the boat. I run a 28 pitch Bravo One 4 blade prop (props have been turned, so its more like a 27 pitch) to a best of 83 MPH on GPS. The deep X-dimension is a killer on top speed...
10-28-2016, 06:18 AM
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Carcrazy, I'll be close to what you have, I'm going with 550-600 hp BBC but, like you, my X dimension was 8". I'm glassing the transom right now and raising the drives 6". I'm also running through merc trannies. Mine is a 77 which only came in small block configured, so gimbals had to be moved out 1 1/2" to allow big block clearance.
10-29-2016, 03:21 AM
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One thing I wanted to point out. There is a big difference between the Merc Trans and the Borg Warner trans (72C Velvet Drive). The Merc Trans you mentioned will not hold up to 600 HP. I made the switch for reliability. Of course that meant moving the engines forward a few inches to accommodate the stronger tranny, but it wasn't a huge deal, there is plenty of room in that engine compartment. Since it sounds like you are doing some re-rigging, it might be something to consider sooner than later.
I decided to not change the X-dimension, but I wish I had. At the time I figured since my hull didn't need any attention, I'd rather not take on that project. I also didn't want to add blower scoops to my hatch covers, which would be require if the engines were raised. Is that what you plan to do, or some kind of raised hatch?
A friend of mine did change the X on his 38 Larry Smith Scarab. Switched drives from #3 SSM to #3A SSM and still (despite the added bulk) yielded about 2MPH increase per inch up.
There are a lot of people with much more knowledge than me on X-dimensions, but your goal of raising your X dimension 6 inches sounds very aggressive. From what you mentioned (starting at 8 inches below the boat) it sounds like you'd result with a prop shaft 2 inches below the bottom of the boat. Modern hulls with step bottoms and pads work with high X dimensions, but conventional V bottoms like our old scarabs will have a definite limit with how high you can go. Sure bravos and speed masters and etc. can be spaced down, so starting hight is the right choice. But if you are using the TRS drives as your post suggests, those drives weren't really designed to work with spacers. The short of it is, that combo doesn't have adjustability without some serious re-rigging. Just my .02 cents ....it'd be a shame to do the first lake test and then discover you can't get on plane. Archer Marine in Costa Mesa, CA knows Scarabs well. Might be worth a call for some good set up info.
I decided to not change the X-dimension, but I wish I had. At the time I figured since my hull didn't need any attention, I'd rather not take on that project. I also didn't want to add blower scoops to my hatch covers, which would be require if the engines were raised. Is that what you plan to do, or some kind of raised hatch?
A friend of mine did change the X on his 38 Larry Smith Scarab. Switched drives from #3 SSM to #3A SSM and still (despite the added bulk) yielded about 2MPH increase per inch up.
There are a lot of people with much more knowledge than me on X-dimensions, but your goal of raising your X dimension 6 inches sounds very aggressive. From what you mentioned (starting at 8 inches below the boat) it sounds like you'd result with a prop shaft 2 inches below the bottom of the boat. Modern hulls with step bottoms and pads work with high X dimensions, but conventional V bottoms like our old scarabs will have a definite limit with how high you can go. Sure bravos and speed masters and etc. can be spaced down, so starting hight is the right choice. But if you are using the TRS drives as your post suggests, those drives weren't really designed to work with spacers. The short of it is, that combo doesn't have adjustability without some serious re-rigging. Just my .02 cents ....it'd be a shame to do the first lake test and then discover you can't get on plane. Archer Marine in Costa Mesa, CA knows Scarabs well. Might be worth a call for some good set up info.
10-29-2016, 05:29 AM
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I'll give them a call this morning if they're open, or Monday if they're not. Currently I've got the merc trannies, I do know where two 72c are and can still do the swap if needed. Does adding the BW require adding in a support for the tranny....currently the merctrans just hang off the motor and slip into the gimbal housing. As far as the hatch goes, my wife and girlfriends would kill me if I were to chop up their tanning deck, so I'll probably end up just raising it and putting intake and exhaust vents on the front and back.
My plan wasn't to re-rig the entire boat, but every time I take something out to replace it, my OCD kicks in and I have to go a little further to change that one little thing, and then the process repeats itself. This all started as a simple repower and has turned into me having gutted the entire boat, complete new interior and custom "race style" backseat, stereo etc etc
The group of guys I run with are all newer hulls (2000) single prochargers engines, 80ish is top speed.....I'd like to be able to run with and past them
My plan wasn't to re-rig the entire boat, but every time I take something out to replace it, my OCD kicks in and I have to go a little further to change that one little thing, and then the process repeats itself. This all started as a simple repower and has turned into me having gutted the entire boat, complete new interior and custom "race style" backseat, stereo etc etc
The group of guys I run with are all newer hulls (2000) single prochargers engines, 80ish is top speed.....I'd like to be able to run with and past them
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11-03-2016, 02:34 PM
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One thing I wanted to point out. There is a big difference between the Merc Trans and the Borg Warner trans (72C Velvet Drive). The Merc Trans you mentioned will not hold up to 600 HP. I made the switch for reliability. Of course that meant moving the engines forward a few inches to accommodate the stronger tranny, but it wasn't a huge deal, there is plenty of room in that engine compartment. Since it sounds like you are doing some re-rigging, it might be something to consider sooner than later.
I decided to not change the X-dimension, but I wish I had. At the time I figured since my hull didn't need any attention, I'd rather not take on that project. I also didn't want to add blower scoops to my hatch covers, which would be require if the engines were raised. Is that what you plan to do, or some kind of raised hatch?
A friend of mine did change the X on his 38 Larry Smith Scarab. Switched drives from #3 SSM to #3A SSM and still (despite the added bulk) yielded about 2MPH increase per inch up.
There are a lot of people with much more knowledge than me on X-dimensions, but your goal of raising your X dimension 6 inches sounds very aggressive. From what you mentioned (starting at 8 inches below the boat) it sounds like you'd result with a prop shaft 2 inches below the bottom of the boat. Modern hulls with step bottoms and pads work with high X dimensions, but conventional V bottoms like our old scarabs will have a definite limit with how high you can go. Sure bravos and speed masters and etc. can be spaced down, so starting hight is the right choice. But if you are using the TRS drives as your post suggests, those drives weren't really designed to work with spacers. The short of it is, that combo doesn't have adjustability without some serious re-rigging. Just my .02 cents ....it'd be a shame to do the first lake test and then discover you can't get on plane. Archer Marine in Costa Mesa, CA knows Scarabs well. Might be worth a call for some good set up info.
I decided to not change the X-dimension, but I wish I had. At the time I figured since my hull didn't need any attention, I'd rather not take on that project. I also didn't want to add blower scoops to my hatch covers, which would be require if the engines were raised. Is that what you plan to do, or some kind of raised hatch?
A friend of mine did change the X on his 38 Larry Smith Scarab. Switched drives from #3 SSM to #3A SSM and still (despite the added bulk) yielded about 2MPH increase per inch up.
There are a lot of people with much more knowledge than me on X-dimensions, but your goal of raising your X dimension 6 inches sounds very aggressive. From what you mentioned (starting at 8 inches below the boat) it sounds like you'd result with a prop shaft 2 inches below the bottom of the boat. Modern hulls with step bottoms and pads work with high X dimensions, but conventional V bottoms like our old scarabs will have a definite limit with how high you can go. Sure bravos and speed masters and etc. can be spaced down, so starting hight is the right choice. But if you are using the TRS drives as your post suggests, those drives weren't really designed to work with spacers. The short of it is, that combo doesn't have adjustability without some serious re-rigging. Just my .02 cents ....it'd be a shame to do the first lake test and then discover you can't get on plane. Archer Marine in Costa Mesa, CA knows Scarabs well. Might be worth a call for some good set up info.
