Indmar 340 vs 350?

[LateNightSalami]

My boat has an Indmar 340 engine in it. I have heard through some conversations that the main difference between the 340 and 350 is the way the computer controls the engines. The implication was that a simple firmware change could be the main component in getting a little more out of your 340 engine. Is there any truth to this? Don't get me wrong, I am perfectly happy with the performance but half of the fun of these boats in having a little something to tinker with.

[Chaabo]

Makes sense to me, but don’t expect too much out of an 10hp increase.

I had two Responses with the 320LCR engine prior to my current one which has the 330LCR. The engine (and all of it’s components) are identical, except for the fuel pump that is now in the tank.

Honestly I couldn’t feel any increase in performance when upgrading from a 320 to the 330 back in 2010.

[LateNightSalami]

4 minutes ago, Chaabo said:

Makes sense to me, but don’t expect too much out of an 10hp increase.

Gotta have the NUMBERS BABY!!....jk

 

Yeah I wouldn't expect much out of it at all. I was wondering if it was even possible. Might be something I want to play with 5 years down the line with all of that free time I don't have (2 kids).

[shawndoggy]

IIRC there's a thread on here from @Engine Nut confirming that Indmar doesn't set HP numbers, and that the mystery HP bump was done by the marketing department.

[kerpluxal]

Not sure if you are comparing values of the same year or different years. They are all 350 blocks. My 2000 Lx was 3?0 hp  and my 2010 lsv is claimed 350....

I disagree a bit with @shawndoggy a bit  as I can see a 10 hp gain.. not really all on ECU but also the boltons used. 2000 was multiport with the Throttle body on a manifold as in a TBI system. It used a restrictive spark arrestor. The 2010 is also multiport, with a Plenum and TB mounted at end of Plenum and a high flow air filter on it. Not sure if they have the same cam in them and injectors, and exhaust manifolds. Better engine management will also increase HP... ie the ECU (probably not the same on boats as they use MEFI). The ECU controls timing, when and how long injectors open, air intake.. etc... etc...

The only issue I see is that there is no easy chip flash systems on the market for boats, specialized software to read MEFI systems, and not sure the software can write change changes to timing and other variables as well.. IMO it would be a heavy investment for 10hp. 

[shawndoggy]

5 minutes ago, kerpluxal said:

Not sure if you are comparing values of the same year or different years. They are all 350 blocks. My 2000 Lx was 3?0 hp  and my 2010 lsv is claimed 350....

I disagree a bit with @shawndoggy a bit  as I can see a 10 hp gain.. not really all on ECU but also the boltons used. 2000 was multiport with the Throttle body on a manifold as in a TBI system. It used a restrictive spark arrestor. The 2010 is also multiport, with a Plenum and TB mounted at end of Plenum and a high flow air filter on it. Not sure if they have the same cam in them and injectors, and exhaust manifolds. Better engine management will also increase HP... ie the ECU (probably not the same on boats as they use MEFI). The ECU controls timing, when and how long injectors open, air intake.. etc... etc...

The only issue I see is that there is no easy chip flash systems on the market for boats, specialized software to read MEFI systems, and not sure the software can write change changes to timing and other variables as well.. IMO it would be a heavy investment for 10hp. 

I'm talking about the HP "increase" that occurred after 2006, when the SBC Gen 1 went to the HFS distributor.

http://www.themalibucrew.com/index.php?/forums/topic/51649-indmar-new-hp-marketing-s/&tab=comments#comment-752122

http://www.themalibucrew.com/index.php?/forums/topic/30583-solve-a-mystery/

 

[justgary]

And those 320, 330, 340, and 350 ratings are almost assuredly peak torque, not HP anyway.  It's not terribly likely you will notice 10 Ft-Lbs of torque added to your upper mid RPM range where the peak torque lives, simply because you don't really have a benchmark for how far you push the throttle.

[LateNightSalami]

13 hours ago, justgary said:

And those 320, 330, 340, and 350 ratings are almost assuredly peak torque, not HP anyway.  It's not terribly likely you will notice 10 Ft-Lbs of torque added to your upper mid RPM range where the peak torque lives, simply because you don't really have a benchmark for how far you push the throttle.

Pretty sure the peak torque rating on the Monsoon 340 is 397ft lbs. They used to label these engines in HP but lately with all the surfing people wanted the torque numbers instead. This allowed marketing to give big bumps in numbers with the latest engines even though the performance isn't really all that different: https://www.indmar.com/engines/

The Raptor 400:

350hp

404 ft lbs

Monsoon 340:

340 hp

397 ft lbs 

 

Edit: The above numbers for the monsoon 340 are the most often quoted ones that I see on forums. At one point I did have some website links to back it up but for the life of me I cannot find them now. They seem elusive for some reason.

Edited October 19, 2018 by LateNightSalami
Elaborate

[formulaben]

16 hours ago, kerpluxal said:

...IMO it would be a heavy investment for 10hp. 

This.  Unless you're trying to both slalom ski and surf, I think you're much better off investing in a propeller upgrade for your core activities if you're trying to improve performance.