1997 Ski Centurion ski/wakeboard boat with 5.3liter EFI power
06-26-2012, 05:18 PM
#1
1997 Ski Centurion ski/wakeboard boat with 5.3liter EFI power Thought I'd make my own thread as I've posted this boat up in a few other peoples:
One of the most difficult parts of the swap was to find exhaust manifolds on a budget that still flowed well. Only answer I found was the ones we used.
Bought this boat over a year ago with a buddy and it had no engine, a crusty interior/carpet, and a family of racoons living in the large rear storage locker of the boat. Supposedly belonged to the owner of Ski Centurion at one point and had a 502ci carb setup in it. Had already a barefoot practice boom, nice stereo, hydraulic steering, and trim plates custom installed before we got it.
Fast forward a year and this 21' ski boat now has new interior/carpet, new rear modern swim platform (2x larger than the original teak deck), completely rebuilt trailer brakes which were toast, 5.3 EFi motor with a used Z06 cam/springs, ported TB, Fbody oil pan, SD tune by Nick @ Newtech using laptop/WBO2 (thanks a ton for going out on the boat and doing a real tune). Guessing it makes 325-350hp which is 75-100hp more than stock. Goes pretty good... hull design seems to limit it to about 45mph.
Justin @ Samberg Fabrication in Pleasanton, CA co-owns it with me and did a sh*t ton of work on it and all the custom fab. Thanks man!
Hats off to Sip at Ski Centurion for knocking out the interior in under a week! Looks great!
Custom features are an "H" pipe aluminum crossover on the exhaust which required 15% more fuel in the tune and really woke it up from a stop, Marine Power exhaust manifolds (most expensive part of the swap aside from interior), custom closed loop cooling radiator system with fresh water heat exchanger, boomin' stereo install with (14) 6x9 speakers, (2) 12" subs, 2000+ watts power. The radiator system was needed as we couldn't get the engine warm enuf with a fresh water open system... was staying only around 80-90* F. Now with a 160* Tstat it never gets hotter than 190* under any conditions.
We are into it for over $10K but it is better than paying $20-50K for some of those other wakeboard boats. Does a GPS verified 45mph in just about any water conditions.
Justin complains of poor fuel economy..... maybe he shouldn't drive at 4,000+rpm/40mph+ all day the entire time around the Delta
In the 2nd picture that is when you run an engine around for a few hours without a dipstick tube! Luckily that was the old interior. We were so excited to get it out on the water we overlooked it! yikes....
Last picture shows the custom H pipe. Works really well!
One of the most difficult parts of the swap was to find exhaust manifolds on a budget that still flowed well. Only answer I found was the ones we used.
Bought this boat over a year ago with a buddy and it had no engine, a crusty interior/carpet, and a family of racoons living in the large rear storage locker of the boat. Supposedly belonged to the owner of Ski Centurion at one point and had a 502ci carb setup in it. Had already a barefoot practice boom, nice stereo, hydraulic steering, and trim plates custom installed before we got it.
Fast forward a year and this 21' ski boat now has new interior/carpet, new rear modern swim platform (2x larger than the original teak deck), completely rebuilt trailer brakes which were toast, 5.3 EFi motor with a used Z06 cam/springs, ported TB, Fbody oil pan, SD tune by Nick @ Newtech using laptop/WBO2 (thanks a ton for going out on the boat and doing a real tune). Guessing it makes 325-350hp which is 75-100hp more than stock. Goes pretty good... hull design seems to limit it to about 45mph.
Justin @ Samberg Fabrication in Pleasanton, CA co-owns it with me and did a sh*t ton of work on it and all the custom fab. Thanks man!
Hats off to Sip at Ski Centurion for knocking out the interior in under a week! Looks great!
Custom features are an "H" pipe aluminum crossover on the exhaust which required 15% more fuel in the tune and really woke it up from a stop, Marine Power exhaust manifolds (most expensive part of the swap aside from interior), custom closed loop cooling radiator system with fresh water heat exchanger, boomin' stereo install with (14) 6x9 speakers, (2) 12" subs, 2000+ watts power. The radiator system was needed as we couldn't get the engine warm enuf with a fresh water open system... was staying only around 80-90* F. Now with a 160* Tstat it never gets hotter than 190* under any conditions.
We are into it for over $10K but it is better than paying $20-50K for some of those other wakeboard boats. Does a GPS verified 45mph in just about any water conditions.
Justin complains of poor fuel economy..... maybe he shouldn't drive at 4,000+rpm/40mph+ all day the entire time around the Delta
In the 2nd picture that is when you run an engine around for a few hours without a dipstick tube! Luckily that was the old interior. We were so excited to get it out on the water we overlooked it! yikes....
Last picture shows the custom H pipe. Works really well!
Last edited by gnx7; 06-27-2012 at 04:42 PM.
06-27-2012, 01:26 PM
#2
Nice, looks like I might be doing a LS swap on my boat soon. I think it spun a bearing on the 400sbc last weekend
.
I picked up a set of marine power manifolds off e-bay a year ago but I don`t have the risers and can`t seem to find anyone who sells them. Oh well time to grab the welder.
Where did you stick the wideband in the exhaust while you were tuning? Your running speed density without o2`s normally right?
What about a fuel pump/lines? I had been thinking of running a low pressure pump and then a high pressure efi pump in a surge tank mounted to the motor since I can`t seem to find marine EFI rated rubber hose. But the last few days I`ve been thinking I will just run a high pressure efi pump in the main tank and plumb all the way back to the motor in stainless hardline.
.I picked up a set of marine power manifolds off e-bay a year ago but I don`t have the risers and can`t seem to find anyone who sells them. Oh well time to grab the welder.
Where did you stick the wideband in the exhaust while you were tuning? Your running speed density without o2`s normally right?
What about a fuel pump/lines? I had been thinking of running a low pressure pump and then a high pressure efi pump in a surge tank mounted to the motor since I can`t seem to find marine EFI rated rubber hose. But the last few days I`ve been thinking I will just run a high pressure efi pump in the main tank and plumb all the way back to the motor in stainless hardline.
06-27-2012, 04:01 PM
#3
I opened an account with Marine Power and can get them. PM me.
We are running an external inline Walbro pump with hi pressure rubber lines and a Corvette FPR.
A 1.5" thick open center block/spacer was waterjetted and sits between the lower and upper manifolds with a drilled/tapped hole for production O2 sensors and another one for a WB02 for tuning. I believe we are running it without O2s as they got fouled by water; however it as tuned with a WB02. The PCM I had for it was an unknown and the timing was super low and tune pretty far off. It could barely get out of its own way and was super down on power. Very rich too!
The engine is a pretty tight fit under our engine cover. I say go for it! Just takes time
We are running an external inline Walbro pump with hi pressure rubber lines and a Corvette FPR.
A 1.5" thick open center block/spacer was waterjetted and sits between the lower and upper manifolds with a drilled/tapped hole for production O2 sensors and another one for a WB02 for tuning. I believe we are running it without O2s as they got fouled by water; however it as tuned with a WB02. The PCM I had for it was an unknown and the timing was super low and tune pretty far off. It could barely get out of its own way and was super down on power. Very rich too!
The engine is a pretty tight fit under our engine cover. I say go for it! Just takes time
Last edited by gnx7; 06-29-2012 at 04:25 PM.
09-04-2012, 10:43 AM
#6
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That's awesome! I have a 99 Supra that I almost converted, but I decided to just rebuild the old small block vortec motor instead. Very nicely done! I had a mastercraft that I put a built ford 351 in that made over 400hp, and anything over 45 the hull would start to porpose, so I know what you're talking about with the hull design. Just slap a big four blade prop on there to dial in your RPM's where you want them at 45 and enjoy all the torque you're gonna gain in the hole shot!
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09-22-2012, 07:55 PM
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I saw another LS boat where the guy did some kind of dry pipe for the wideband tuning - his was in OL, so no O2 sensors after the tuning... Did you have to put in some sort of pipe for the wideband during tuning?
10-02-2012, 02:28 AM
#10
In one of the aluminum spacers we had machined between the bottom part and the riser there was a hole tapped for WB02 sensor. We just run a plug in it normally. That was how the tuner got it to where it is now.
Been using it a ton this summer. Pretty much every weekend it gets taken out.
Got the trim tabs to work and it doesn't porpoise as badly at top speed now.
Been using it a ton this summer. Pretty much every weekend it gets taken out.
Got the trim tabs to work and it doesn't porpoise as badly at top speed now.
