2010 VLX- 350 to 383..

[mgb1974]

I purchased a 2010 VLX in the spring to replace my 2002 VLX. The 2010 has 1860 hours on it and lower/uneven compression. I bought it at a good price with the intention of rebuilding or replacing the motor in the fall. 

Boat has been good this year (put 25 hours on it so far) but for sure under powered even with the 2249 prop on it. 

Id like to put a 383 cubic inch marine long block in it to replace the 350 monsoon long block. Question is will the computer handle the increase in cubic inch? I know tunes really dont exist for marine motors. My experience with car engine seems to lead me to say yeah it shouldn't be a problem but wanted to see if anybody on here has any insight. Didn't find much with the search function. 

Plan would be to replace the engine mid to end of September.

 

Matt

[23LSVOwner]

You would probably have to get the ECM reflashed or even get a new one.

[mgb1974]

Still researching for information. Surprisingly not alot out there on this subject.

I emailed http://mefiburn.com/mefiecms.asp and asked them the question. I have the E-Control MEFI on my boat.

If it is to much cost or possible problems ill just do the 350 rebuild. 

[shawndoggy]

I think you are on the right track with contacting MEFIBurn. IIRC didn’t the hammerhead motor of that vintage also use different intake and exhaust manifolds?

Edited August 14, 2019 by shawndoggy

[mgb1974]

46 minutes ago, shawndoggy said:

I think you are on the right track with contacting MEFIBurn. IIRC didn’t the hammerhead motor of that vintage also use different intake and exhaust manifolds?

Bob at MEFIBurn said he can not flash that EFI (E-Control) and doesn't know anybody that can.... More digging to do. 

[shawndoggy]

Just now, mgb1974 said:

Bob at MEFIBurn said he can not flash that EFI (E-Control) and doesn't know anybody that can.... More digging to do. 

Oh bummer.  I'd bet your are SOL then.

[Eagleboy99]

2 hours ago, mgb1974 said:

E-Control MEFI

https://azspeed.com/product/mefi-2-ecus-for-marine-engines/

[mgb1974]

14 minutes ago, Eagleboy99 said:

https://azspeed.com/product/mefi-2-ecus-for-marine-engines/

Sent them a email, everything on there site is for MEFI 1 to 4. The E-Control MEFI is different from what I gather. 

[Eagleboy99]

Apparently you can get the Indmar "e-control" boxes  for like a grand or so.  

[Brap20]

mgb1974,

Going from the 350 to 383 is possible, I am just finishing up doing this with a 2009 VLX. I also have the single plug E-Controls ECM. Any Malibu dealership can reflash the 383 tune onto the ECM. My local dealer has been less than even slightly helpful and refused to reflash it stating "too much liability." I ended up sending mine back to Indmar and they flashed it for me. 

shawndoggy

No, the intake and exhaust manifolds are the same. Everything is the same except for the heads (which are the Chevy Fastburn aluminum heads) and internal components. 

Hope this helps

[mgb1974]

1 hour ago, Brap20 said:

mgb1974,

Going from the 350 to 383 is possible, I am just finishing up doing this with a 2009 VLX. I also have the single plug E-Controls ECM. Any Malibu dealership can reflash the 383 tune onto the ECM. My local dealer has been less than even slightly helpful and refused to reflash it stating "too much liability." I ended up sending mine back to Indmar and they flashed it for me. 

shawndoggy

No, the intake and exhaust manifolds are the same. Everything is the same except for the heads (which are the Chevy Fastburn aluminum heads) and internal components. 

Hope this helps

Awesome! Thanks for information.

 

mind saying how much Indmar is charging to reflash?

[Brap20]

PM sent

[MadMan]

I did the 350 to 383 swap with my '00 monsoon 7 years ago.  I wasn't looking for more power, just moving the power down to a lower RPM, more inline with what a towboat needs.  I didn't change anything on the engine except the stroke (stock heads, cam, etc).

My plan was not to reflash the MEFI, but tune using the old school method of increasing the fuel pressure such that the injectors squirt out 10% more fuel, since the engine is 10% bigger.  I installed a wide band o2 sensor and it showed I actually need to decrease the fuel pressure.  I think GM/Indmar were super conservative with their fuel map because it's a non-feedback (no o2) system.  I have hundreds of hours on it, still running great.

[23LSVOwner]

17 minutes ago, MadMan said:

I did the 350 to 383 swap with my '00 monsoon 7 years ago.  I wasn't looking for more power, just moving the power down to a lower RPM, more inline with what a towboat needs.  I didn't change anything on the engine except the stroke (stock heads, cam, etc).

My plan was not to reflash the MEFI, but tune using the old school method of increasing the fuel pressure such that the injectors squirt out 10% more fuel, since the engine is 10% bigger.  I installed a wide band o2 sensor and it showed I actually need to decrease the fuel pressure.  I think GM/Indmar were super conservative with their fuel map because it's a non-feedback (no o2) system.  I have hundreds of hours on it, still running great.

If you only increased the stroke it would have been a 377.

 

4.0 x pi x 3.75 = 47.12389 x 8 = 376.9911(377cid)

 

Most still call it a 383 because of the stroker crank.

[MadMan]

I thought I would mention the one thing I'd do different in my swap (it really has nothing to do with going to a 383 though).  I'd install an oil pan with the sump on the correct end for a v-drive.  The stock one's great for an I/O or direct drive, but on a vdrive, with ballast for wakeboarding or surfing, it will get sucked dry.  The result is falling oil pressure when accelerating.  I currently overfill the oil ~2 quarts to overcome this.

[Brap20]

When I built mine I used all Indmar 383 specs so I just went ahead and had my ECM reflashed. It's based off of the Chevy SP383 which replaced the zz383. This setup still uses a 4" bore but uses a 3.8" stroke to get to about 382cid, which is close enough. The block does have to be clearanced to use this stroke though, otherwise the rod bolts will hit. 

MadMan,

Do they make a reverse oil pan? I figured the sump was fixed towards the rear of the engine as that's where the oil pump pick up is. 

[Steve B.]

13 hours ago, MadMan said:

I did the 350 to 383 swap with my '00 monsoon 7 years ago.  I wasn't looking for more power, just moving the power down to a lower RPM, more inline with what a towboat needs.  I didn't change anything on the engine except the stroke (stock heads, cam, etc).

My plan was not to reflash the MEFI, but tune using the old school method of increasing the fuel pressure such that the injectors squirt out 10% more fuel, since the engine is 10% bigger.  I installed a wide band o2 sensor and it showed I actually need to decrease the fuel pressure.  I think GM/Indmar were super conservative with their fuel map because it's a non-feedback (no o2) system.  I have hundreds of hours on it, still running great.

Wow. Wish I had that knowledge !

[23LSVOwner]

On 8/16/2019 at 8:57 PM, Brap20 said:

When I built mine I used all Indmar 383 specs so I just went ahead and had my ECM reflashed. It's based off of the Chevy SP383 which replaced the zz383. This setup still uses a 4" bore but uses a 3.8" stroke to get to about 382cid, which is close enough. The block does have to be clearanced to use this stroke though, otherwise the rod bolts will hit. 

MadMan,

Do they make a reverse oil pan? I figured the sump was fixed towards the rear of the engine as that's where the oil pump pick up is. 

Might be a possibility with a little work?

 

https://www.modernperformanceclassics.net/ShowItem/101370 62-67 Chevy II 2 Small Block V8 Oil Pan.aspx

 

[Brap20]

Interesting! I bet it would fit as the SBC platform has not changed much over the years. The only issue I can see is that is a left side dipstick oil pan and mine is on the right side. 

[MadMan]

15 hours ago, Brap20 said:

Interesting! I bet it would fit as the SBC platform has not changed much over the years. The only issue I can see is that is a left side dipstick oil pan and mine is on the right side. 

There was a difference made to sbc oil pans in the mid 80's, they changed the shape to accommodate the single piece rear seal.

I bought either a Mercruiser  or OMC pan form the 90's that has an extended rear sump, it comes to within a few inches of the front.  My plan was to use it along with a Chevy II oil pump and pickup.

Haven't done the swap yet.

[Brap20]

Ah, yes. Forgot about that. I believe that switch was made on the rear main seal in '86 or so. 

[mgb1974]

On 8/16/2019 at 8:09 AM, MadMan said:

I did the 350 to 383 swap with my '00 monsoon 7 years ago.  I wasn't looking for more power, just moving the power down to a lower RPM, more inline with what a towboat needs.  I didn't change anything on the engine except the stroke (stock heads, cam, etc).

My plan was not to reflash the MEFI, but tune using the old school method of increasing the fuel pressure such that the injectors squirt out 10% more fuel, since the engine is 10% bigger.  I installed a wide band o2 sensor and it showed I actually need to decrease the fuel pressure.  I think GM/Indmar were super conservative with their fuel map because it's a non-feedback (no o2) system.  I have hundreds of hours on it, still running great.

Appreciate the feedback. I’m going to order the marine 383 from Raptor Engines. Greg @raptor said he has had customers do the swap with out changing anything on the tune with success.

 

[LXRBarefooter]

On 8/22/2019 at 11:21 AM, mgb1974 said:

Appreciate the feedback. I’m going to order the marine 383 from Raptor Engines. Greg @raptor said he has had customers do the swap with out changing anything on the tune with success.

 

Digging up an old post here, did you have any luck with this 383 change out using the existing Monsoon 350 marinisation kit and ecu? 
 

Did it end up being a drop on replacement or did you need to get a 383 ecu tune for it?

[mgb1974]

Check out my thread, 3 seasons later no issues. I probably should send the ecu in to get flashed, might be leaving some power on the table.

 

 

 

[justgary]

It isn't lost power you should worry about.  I would think that running lean would risk burning a piston or rubbing it dry against a cylinder wall.  If you are running lean and getting away with it, maybe it is only in a part of the throttle range where you just don't run the engine much. 

I would think it is worth either flashing the ECM or raising the fuel pressure to make sure you aren't lean.