V-P 5.7 Gxi intake on 383 stroker?

[686SPORT]

My marina just inherited a Chaparral 265Ssi with a trashed V-P 5.7 GXI-G over 1.95 DP with F4 props. I am interested in buying this boat, since we previously owned the same model with V-P 8.1. Real world weight estimated at 5600#. I feel that the regular 5.7 would be underpowered when skiing or cruising this hull with 5-6 adults aboard. Not sure the 8.1 is a viable choice going forward, but a stouter SBC in there might perform close enough to make the boat enjoyable. Why not start with a new motor and remove doubt about buying somebody else's problems?

Online 383 offerings include, for example, an ATK HP 96 stroker with SCAT crank and rods and hyper pistons; 9.1 compression; 210/215 cam profile; and 1.5 rockers. This motor seems powerful enough for the job without risking water reversion or detonation.

The big question is, can the GXI intake manifold/FI be bolted to this [or other, similar] engine's Dart aluminum heads and be made to work?
tia, 686SPORT

 

[BRICH1260]

I don't think you can use the fuel injection system from the GXI on the stroker as the ECM is not compatible with the new engine. You may have to find a carb to put on it and I dont know if a 4 bbl carb will fit the GXI manifold. A few years back I considered the same process but ended up going back with the GXI.

 

[686SPORT]

I don't think you can use the fuel injection system from the GXI on the stroker as the ECM is not compatible with the new engine. You may have to find a carb to put on it and I dont know if a 4 bbl carb will fit the GXI manifold. A few years back I considered the same process but ended up going back with the GXI.

Yeah, but I seem to recall reading somewhere that the ECM can be reprogrammed to work with the stroker. I'm not too keen on buying a new engine when there are already doubts that it can do the job. Guessing that the 350 is a bit less than ideal since you were looking into this same upgrade. Sunesta may have the same hull as 265; they are both 22 degrees and about the same weight.

 

[alldodge]

The GXI-G had vortex heads so if the motor your buying has vortex heads the intake will bolt up (8 bolts)

The GXI-G comes with a 555 ECM, and if you can find someone which can reprogram it then you can use it, but that is the "if". Otherwise it's buying a used 555

 

[Scott Danforth]

go to 9.6:1 if you can while sticking with the vortec headed small block. I would run a 6.2 LS motor. Volvo was getting 430hp from them

 

[686SPORT]

The tow vehicle for our first Chaparral had a 6.0 LQ4 that made amazing power and would sustain 5000 rpm for as long as you asked it. LQ/S swap is probably beyond my abilities and budget, though. Trying to keep things simple by staying within the same general engine family as the 5.7 GXI.
Looking around the 'net at LS swap sites, one can find lots of links to places that can easily [they say] reprogram ECM's to account for the extra cubic inches. Was hoping someone on here had first-hand experience of that simpler swap.
Thanks for all replies, 686SPORT

 

[Scott Danforth]

I believe the dry weight is 5833# for your boat. which means the wet weight is close to 7K. thats almost needing twins weight category.

Not sure there is enough power in a small block for getting out of the hole quick enough to go skiing. with a change to the IPS drive, would make one heck of a wake surf boat.

I would swap to carb if you are dead set on building a SBC stroker for that heavy boat. go with an edelbrock air-gap intake and a 2" carb spacer to get plenum volume for mid-range torque.

the stock GM MPI intake is mediocre for building torque. you could swap to a 4150 style MPI intake with a carb spacer, then you are on your own for tuning unless you have the engine dyno tuned

there are also supercharger kits for the SBC. that would get you in the 450hp range. can get most of that torque where you need it if you are interested in water sports

 

[686SPORT]

We bought a 265Ssi new at Centerville Waterway in VA. V-P 8.1/375. After break-in she hit 56 statute mph on the gps both ways running the canal there. Real-world cruise at 2900 rpm [the sweet spot, to my ears] returned a shade over 3 mpg. She would pop up two adult slalom skiers with ease, with four other adults in the boat. I would be happy with 48 or so mph and easily getting up a solo slalom skier as performance standards for a replacement SBC in the 265 I'm looking at.

Previous boat was a SeaRay 230 cuddy with Merc 260 and Alpha One. She would pull up two slalom skiers, but it took a LONG time with everybody up forward to help lift the stern. Fuel mileage at cruise was closer to 2.0. Playing with different props - all aluminum - got a best of 44 mph. I guess a dp drive would help with skiing, but I agree overall performance with a 5.7 in a 265 would disappoint.

Scott Danforth, after reading the 4 pages of the 2012 SBC thread from your sig, I can safely observe that your power needs are greater than mine. Even with my lower performance standard, the most problematic part of your reply was the statement "stock GM MPI intake is mediocre for building torque." My bias against going to a carb on the stroker is based on expectation of mediocre mpg's and my not having any experience tuning 4-barrels. [Sidedraft SU's and Webers, no problem.]

Bottom line: it looks like the notion of using V-P 5.7/320 intake on a stroker is a bad idea. Thanks for saving me the trouble. Where I'm boating now, marinas selling gas other than 87 are few and far between. Hence my desire for a milder cam and lower compression. Not going back to using octane booster, either.

One final question: is your current engine based on a 496, and if so, do you find that parts for maintenance and repair are still readily available?
686SPORT

 

[Bt Doctur]

I have cast Dart heads

 

[Scott Danforth]

We bought a 265Ssi new at Centerville Waterway in VA. V-P 8.1/375. After

the 8.1 big block put out about 60% more torque than the 5.7 at 2000 RPM. 440 ft lb for the stock 8.1 and about 275 for the 5.7. the 375sp is a fueling cut-off rating. same block with a minor change to fuel map will do 475. More if you want to play with injectors and other bits from Raylar

. Where I'm boating now, marinas selling gas other than 87 are few and far between. Hence my desire for a milder cam and lower compression. Not going back to using octane booster, either.

I run pump swill from everywhere. I dont use octane booster. Im currently running ~ 9.5:1 on the 468. the previous SBC was 9.4:1 (stock bore/pistons)

Previous boat was a SeaRay 230 cuddy with Merc 260 and Alpha One. She would pull up two slalom skiers, but it took a LONG time with everybody up forward to help lift the stern. Fuel mileage at cruise was closer to 2.0. Playing with different props - all aluminum - got a best of 44 mph. I guess a dp drive would help with skiing, but I agree overall performance with a 5.7 in a 265 would disappoint.

your searay 230 cuddy was 4200#. however the SBC in the Chap 265 will be similar performance

One final question: is your current engine based on a 496, and if so, do you find that parts for maintenance and repair are still readily available?
686SPORT

No, I built my 468 out of a gen VI 7.4 liter pulled from a 1 ton work truck. with a low mileage forged crank, new rods, and .060 over pistons and a set of merlin heads. I build my own motors and do my own repair...... because there is NOTHING on my motor that the average marine mechanic would have a clue about, and because I have been spinning wrenches since I was 3

 

[686SPORT]

Mercruiser has made a 383 that comes complete with intake and ignition; this is the one with the flame graphics on the spark arrester [!]. There are reman versions of this engine for sale out there. Anyone know of a successful mating of this engine to a V-P leg and electronics? The 555 controller seems to be common to both Merc and V-P.
For example: https://www.mercruiserparts.com/mercury-mercruiser-8m0188296-reman-383-mag-bravo-engine?srsltid=AfmBOoqmcq03gdpRkYMHYu8_hJDchhC76_0i0rskNrkaS_uHS3QWBy43

 

[Scott Danforth]

You have to throw the accessories , raw water pump, exhaust and coupler away as they are different than the VP stuff. The block is the same.

Additionally the Mercruiser fueling is a bit lower than what VP does, so you're giving up some performance

And they come with the block-busting single point drain system which I would remove.

The reman Mercruiser is not a good deal from a financial side . But they have flames on the vanity cover.

You would be money ahead to get a reman from Michigan Motorz and get EFI Bob to reprogram yours

 

[686SPORT]

Thank you.

 

[686SPORT]

Reached out to Michigan Motorz. Here is part of their reply: "At this time, we do not offer a 6.2L Volvo replacement." Near as I can tell, V-P never offered the 6.2 - at least in the years around 2005-6, which is when this Chap was built.
Anyone know of an online resource that could help with putting together a good hybrid Merc/Volvo powerplant? The suggestion of an LQ/S/T long block is starting to look better - IF a good fit can be found for fueling and ignition that will talk to the V-P ECM. This would involve working with a marine shop that is willing to take on such a project. All my old racing engine builder buddies are either retired or pushing up daisies.
One more potential showstopper that needs to be addressed: how to assess the condition of the sterndrive. I guess popping the lower drain to see what comes out is a first step; then seeing if the props can be removed comes next. Or can you just take a sample from the drive's reservoir up top?

 

[Scott Danforth]

VP never used the Gen 1 motor at 6.2 liters. They used the 8.1 until 2014 (6 years after GM quit making them)

They adopted the LS Gen 3 and Gen 4 motors

Going 6.2 is easy
Get a 6.2 long block (no stuff bolted to it)

Such as this one. https://michiganmotorz.com/6-2l-377ci-stroker-base-marine-engine-2002-2009/

Use your GXI intake
Use all your VP accessories
Buy new VP exhaust manifolds
Use your VP flywheel and coupling
Use your GXI wiring and ECM, however send your ECM in to MEFI Bob. Make sure you talk to him. The guy knows his stuff

You really need a VP manual for your drive. The upper and lower have one fill, one drain and a gear oil pump on the vertical drive shaft

 

[686SPORT]

aka Bob Madera?

 

[Scott Danforth]

OBD Diagnostics

obd2allinone.com

 

[686SPORT]

As luck would have it, Gxi-G is the first V-P offering that doesn't use the 555 engine management system.

Per Bob: "We do not deal with that E-controls Volvo EGC ecm at all, so I can not help you. See: http://mefiburn.com/ecmrepair.asp"
A look at that link shows that all V-P's up through "Gxi-F" have 555 ecm's that Bob can retool, but not Gxi-G.

A conversation with my one remaining race engine expert confirms that virtually all racers have stopped using local engine builders in favor of buying from one of the many crate engine resources in our great country. That is not a bad thing because there are enough crate suppliers out there that one can buy a well-machined product that includes just the right mix of cam, compression, and so forth. For instance numerous sources offer cams with the 114 degree lobe separation angle that is recommended to avoid water reversion.

Thanks to all for sharing your knowledge and experience. Unless one of you can suggest how to get the 2006+ V-P ecm reprogrammed, I will be looking in other directions for a good deal on my next boat.

 

[Scott Danforth]

You could swap to a Duramax diesel, or a Big Block or simply go to a carb on an SBC stroker

 

[Lou C]

The right size carb with the correct jetting will give you what you want and will be easy to maintain with widely available Holley or Edelbrock parts. If not used to starting a carbed engine with a choke that’s just a little learning curve. Best part of this way is you will be free of Volvo’s 2 bad habits when it comes to parts:
Very high parts cost
Parts get discontinued
I can find any part I need for a Quadrajet that has not been made in 30 years.
Thank the auto resto hobby for keeping the carb alive.
Meanwhile EFI parts for older Volvos are to find and for OMC/Volvo products nearly impossible.