Upgrading Gen 5 VP V8-300 (300HP) to a V8-350 (350 HP)

[gerryvz]

From everything I've read, including the technical manuals and specifications, the current "Gen 5" Volvo Penta 5.3-liter V8-300 and V8-350 engines and all accessories are EXACTLY the same, save for a different computer control unit that "de-powers" the base engine to 300 HP.

If this is indeed the case, as a V8-300HP owner, would it just be a matter of replacing the ECU to up-power the engine by 50 HP? It would I'm sure make a noticeable difference on my boat, a 2019 Regal 28 Express.

Has anyone done this and/or know about doing this? Literally I cannot find a single different part between the physical engines.

Any help or advice is welcomed!

Cheers,
Gerry

 

[jimmbo]

Have you checked all the parts in the Valve Train?
Are the Heads the same?
What about Induction System?
Do the 2 engines have the same WOT Rpm range?

 

[flashback]

I can't imagine that just changing the spark advance curve would buy 50hp. But I've been wrong more than right..

 

[jimmbo]

To get more HP, either Rpms and/or, Volumetric Efficiency has to increase, in most cases, both. There might be a Timing change, but these engines can only handle so much advance before they start Detonating. If more fuel is added, then the Injectors may be different. It is so much easier to get more power out of Carbed Engine, than these pesky EFI systems

 

[gerryvz]

Have you checked all the parts in the Valve Train?
Are the Heads the same?
What about Induction System?
Do the 2 engines have the same WOT Rpm range?

Attaching the VP spec sheet for both engines. The HP and torque curves appear to be identical until around 4,500 RPM, and then diverge a bit. I believe this is just a different ECU program to deliver more fuel at the higher RPM ranges.
Heads, induction and exhaust manifolds/risers are identical between the two engines.

 

[Scott Danforth]

its a different fuel map

you will need to provide your serial number to buy a new ECM, and they will flash it with the same program you have.

a few years back, the marine industry clamped down on reflashing

 

[gerryvz]

its a different fuel map

you will need to provide your serial number to buy a new ECM, and they will flash it with the same program you have.

a few years back, the marine industry clamped down on reflashing

You mean it wouldn't be possible to buy an ECU with the higher power rating / remapped fuel and ignition curve, separately? They would only sell it as a package with a complete engine?

My bet is that it's probably an EPROM inside the ECU case that has all of the maps programmed in it.

 

[Scott Danforth]

You mean it wouldn't be possible to buy an ECU with the higher power rating / remapped fuel and ignition curve, separately? They would only sell it as a package with a complete engine?

correct. just like you can not have your 4.3 250hp reflashed to 280hp. even though the whole engine is the same, only a fuel mapping difference.

unless you find a dealer willing to reflash your ECM without documenting it (good luck)

 

[gerryvz]

One question - are the ECUs for these VP engines computer-coded directly to the individual HINs / engine serial numbers, or could you take a used ECU from another boat and install it with no issue?

 

[gerryvz]

I came across a similar thread on a Cobalt forum, except for the V-6 variant of these Gen V motors:

Flash VP240 to 280? - Cobaltchat.com

A Forum for Cobalt Boats. The Cobaltchat.com web forum provides an active community for owners of Cobalt Boats to share advice on using, buying, servicing, and enjoying Cobalt boats.

www.cobaltchat.com

 

[tpenfield]

The PCM will have the engine serial number 'flashed' into it. You'd have to get a stand-alone PCM for the 350 HP. Not sure you could get that though . . .

Does the Regal 28 have just a single engine? If so, I don't think 50 extra HP is going to be much of a solution.

 

[gerryvz]

The PCM will have the engine serial number 'flashed' into it. You'd have to get a stand-alone PCM for the 350 HP. Not sure you could get that though . . .

Does the Regal 28 have just a single engine? If so, I don't think 50 extra HP is going to be much of a solution.

Yes, the Regal 28 Express is a single VP with DPS outdrive. I agree that for most cruising, it will not be a major upgrade given the similarity of the HP and torque curves. A 6.2L repower at 380 or 430HP would be more effective. It just seemed like low-hanging fruit given that the hardware is 100% identical......

 

[tpenfield]

Surprising that Regal puts the 300 (or even the 350) HP engine in that boat. Definitely could use 400+ HP. Many 28 footers have twins for good reason.