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Stingray 230 LX Engine Swap & Whipple

Old 02-07-2020, 10:03 AM
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Default Stingray 230 LX Engine Swap & Whipple

Hi all,

Just wanted to share details of a project that I have been working on with my 2007 Stingray 230 LX Bowrider. Two winters ago I had a boat with a dead 350 mag mpi and elected to move forward with a new engine in the existing boat. I swapped the old engine for a new Mercury Remanufactured 385 performance tuned with headers. The engine is rated 350hp stock and 370hp with headers. I also have captains choice exhaust. Over the last two summers I put about 80 hours on the new engine and found that it improved my top speed by about 5mph. I swapped the original speedo for a GPS so it is hard to get exact improvement numbers but that is about right. The old speedo was more than 10% high based on rpm - WOW. I can now hit 60 on GPS with a light load and some light chop and 57 or 58 regularly.

Now that we are broken in it is time to take advantage of the beefed up internals in this engine. This winter I am adding a whipple supercharger, dual hydraulic steering and trim tabs. I am also swapping the drive for a Bravo XR since my steering was shot and my old drive was approaching 500 hrs and had some wear. I went Bravo XR and not a shortie after all of the good advice I got on this forum and some other searches. The boat is just not fast enough to really benefit from the shortie and planing and turning will be too compromised for the small added benefit. And ... my kids are going to be driving this thing in a few years. My marina found me a refurbished for close to 1/2 price so easy choice.

I have thought a lot about swapping to a different cam but want to run it for a summer and see what it is like first. I also love the sound of this engine and am reluctant to change it too much. That being said, the Seven Marine supercharged 627hp outboards use the LS9 cam and from what I hear they sound very good. It is 211/230/122 vs the stock one in the 385pt which I believe is more like 214/218. With the supercharger the additional exhaust duration should be very meaningful and the 122 LSA would hopefully keep idle reasonable. Any thoughts on cam are welcome as it may be next winter's project. I will also have to get my ECM custom tuned too which I know is riskier than the proven Whipple tune I am getting now. Lots to think about.

Thanks to everyone for posting so much great info on this board. Will post speed and driving characteristics when I get it in the water.






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Old 06-08-2020, 09:14 AM
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Hi all,

The supercharger is now installed but we are running into what appear to be fuel issues. Huge thanks to Whipple and BBlades who have been great to work with along the way. After installing the supercharger we could not start the motor at all. Turned over but would not catch. With 10 degrees of mechanical advance it fired up but would only get to 3,000 rpm or so before losing fuel pressure. With some tweaking on advance and fuel pressure we were able to get it to 4,000 but same thing. Then we changed the pickup from the tank and hardwired the low pressure pump. We have reached 5,000 rpm but only with 26gpm fuel burn and with speed of 64mph vs. 60mph pre-supercharger. I have not driven it yet to see firsthand and confirm tach/burn numbers but hope to later today. Has anyone had any fuel issues like this when adding a supercharger to an EFI motor?

Some additional data points:
1) the prop slip seems way too high here so I wonder if the marina had it trimmed too high. The 21 mirage plus I used to run went 60 at 5000 rpm same GPS speedo. Now I am running a 4 blade 24 pitch BBlades. Should go at least 69 with same slip and it feels like it hooks up better than the Mirage did.
2) The 385 performance tuned with the whipple is supposed to be 515hp. With my headers/thru hull exhaust it could be slightly higher as the motor is rated at 370 with headers by Mercury. 515hp should be around 40gph. Much higher than 26.
3) Based on speeds and associated hp from other Stingray bowrider owners 64mph is probably achieved with 400 - 425hp - although an 8.2 burns over 30gph at 425hp so that is a headscratcher too.

Any thoughts or advice are welcome. Hope to have more info to add here in a day or two.

Last edited by StingrayBR; 06-08-2020 at 09:28 AM.
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Old 03-22-2021, 12:09 PM
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Hi all,

Update that the boat has spent the winter in the highly competent hands of Saris Racing for some additional engine work and tuning. New higher CFM heads with larger chambers to reduce compression to about 8:1, cam, intake, ECM, higher boost pulley (targeting 8psi), and a few other things. The boat ran between 66-68 mph GPS last summer with a high of a hair over 70 on a sub 40F morning in September exhaust closed - too early to make that kind of noise. I tried a number of props from Bblades who was also great to work with. The 4 blade OB/FX labbed to reduce diameter was probably my favorite prop although I have not yet labbed the Mirage 25 which was about the same speed stock with more bow lift. Both props would cause chining if over trimmed but reducing the diameter of the Bblades prop reduced the stern lift and helped tremendously. The boat was definitely running a little rich with the tune so I enthusiastically am taking Jason's recommendation to change and custom tune it. CID will be slightly higher with the new heads - 391 now I believe. Objective is to see what the potential horsepower is here without going so far as to require mid-summer adjustments of valves or making the idle too choppy with too much cam.

Will post more when the ice thaws and I can try it out
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Old 03-22-2021, 12:37 PM
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Just trying to follow along.
This is the engine ?
C&M Marine Distributing - Remanufactured 385 Performance Tune Engine 8M0064807

If so, not sure why reference on LS9 cam. Totally different engine. Most regular sbc use a 112-114 lsa cam when supercharged.
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Old 03-22-2021, 01:38 PM
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Originally Posted by StingrayBR View Post
CID will be slightly higher with the new heads - 391 now I believe.
Engine displacement being calculated with chamber volume as a factor is a new one to me.
I guess technically, but I've never seen it done customarily.
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Old 03-22-2021, 04:32 PM
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Yes, it started with the 385 PT from Merc Reman. I got the idea for the LS9 cam from the Seven Marine 627 outboard which is a 9psi supercharged similarly sized engine. A friend of mine has 3 of them on his boat and raves about the performance and idle quality. You are right about the LSA - super high
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Old 03-22-2021, 04:53 PM
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I think you are right Cheech and I misspoke there. Displacement is borexstroke so head volume is not in the calc. I was factoring the increase in total volume with the new 72cc heads necessary to get from a 9:1 closer to an 8:1. Going aluminum on the heads to squeeze a bit more PSI in there and lose a little weight.
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Old 03-22-2021, 05:22 PM
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Okay. On same page now. That LS9 cam is quite unique, Nothing iíve ever remotely seen on normal 23 degree small block.

Your in good hands at Sarisís shop.

Did you figure out your fuel supply issue or waiting for lake to be usable until you know ?
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Old 03-22-2021, 07:30 PM
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Fuel issue is solved with an upgrade and definitely ahead of water test. Not sure exactly what Saris is doing but I know it needs attention. I definitely feel in good hands. This is my first custom engine build so I don't have a lot to compare with but I could not feel more comfortable.

I think I was running closer to 470hp based on calculating horsepower and speed from the original engine (300hp/~56mph), New 385pt (350hp/~60mph), Others experience with the 425hp in a 230sx (65ish mph) Whipple added (?hp/68 - 69mph). I cannot really count the 70 because it was in the 30s and super dry. These are ideal condition speeds all around. The shorter intake manifold that comes with the Whipple is great for fit and is very compatible with the tune but it compromises evenness of air/fuel distribution. By replacing with a taller one with better mixing they can custom tune a leaner mix adding power.
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Old 03-22-2021, 10:20 PM
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If it is of any help, I had a 496 Mag (375HP) 230SX closed deck, with a 25"P Mirage prop and it ran around 67 mph GPS, I think if i kept trying and was in the boat alone I could coax 68 mph out of it. I had that 25P Mirage labbed by BBlades and it ran the exact same mph but with a bit more bow lift. I sold the boat due to the poor performance, but the boat itself was fine. From reading the internet it appears the same boat with a 496 HO ran more like 70 - 72 mph.
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