325 Monsoon performance mods

[Andrew63]

That still seems like a low RPM and top speed for a Monsoon powered DD.

Agreed, but it is a slight improvement.

Forgot to mention I ski at near enough sea level on tidal rivers

I shall be watching this thread for developments as while it is an improvement, it still bugs me.

[OhTwoBu]

It'll be three weeks until I'm back home and can work on it but plan on hitting it heavy when I do, in between snowboarding days of course

I'll start with tune-up, and post back with my prop info and will likely end up with another. I want to post a video from my GoPro of my boat pulling from a dig, with wakeboarder, and five people, and let you guys see how you think it's running, but can't seem to figure out a way how.

[OhTwoBu]

Which version of MEFI would I be running? 2002 325 Monsoon.

[OhTwoBu]

Just posted to YouTube instead, please take a look and see if a properly running 325 pulls and sounds like this.

http://www.youtube.com/watch?v=mQ6lqrZJHjk

[edwin]

Agreed, but it is a slight improvement.

Forgot to mention I ski at near enough sea level on tidal rivers

I shall be watching this thread for developments as while it is an improvement, it still bugs me.

I personally think the improvement is bigger than you think. You're not comparing apples to apples with the prop change. You jumped from a 13x11.5 to a 13x12, yet gained 150 rpms at WOT. Assuming both props are the same cup / condition, the 13x12 will spin fewer rpms at WOT than the identical prop in 13x11.5. My testing over the years has shown apprx 50-75rpms diff't between the two pitches.

If the boat gets out of the hole good with the 13x12, holds speed well, etc., I'd stop looking for issues and just use/ enjoy it.

[dtm8119]

Which version of MEFI would I be running? 2002 325 Monsoon.

I have a 2002 and mine is MEFI 2. To confirm, I'd grab the Delphi number off of the ECM and double check with Bakes or Indmar.

Dan

[electricjohn]

My 2003 monsoon is running MEFI 4 version a. I doubt they skipped MEFI 3.

[justgary]

Which version of MEFI would I be running? 2002 325 Monsoon.

MEFITuning.com has a part number table that will tell you what version you have. I have no interest in changing tables, but getting data from the engine while it is running correctly can sure help diagnose problems later. I'm seriously considering getting a scan tool for my engine.

[OhTwoBu]

Well gents, the more time I have here to research, the more I think I would like to tackle a rebuild of my engine. With the exception of any machine work (which shouldn't be extensive on a 350 hour engine) I can do this myself. The vision is to build my own Hammerhead. Start with a 3.8 throw crank and 4.0 bore (383) or punch out to .030 over. Keep the 5.7 rods. The key here would be getting the right pistons for around 9.7 to 1, and the right cam for max low-end grunt. The Hammerhead uses Aluminum FastBurn Heads with larger valves and runners than the Vortecs on the Monsoon, but it seems the iron Vortecs are no slouch and are good for plenty of power so I'd prefer to keep those and just massage where appropriate. Not sure if the HH uses a different intake and TB, and it uses some pricy ETX aluminum exhaust manifolds. I think if I just stuck with a new rotating assembly and cam and worked the Vortec heads 375-400 horsepower should be attainable. Then, of course the computer… Flame on fellas!

[justgary]

What about picking up a crate or junk yard engine to work on so you can keep using your boat until you are ready to drop the new one in?

[WheelerWake]

Well gents, the more time I have here to research, the more I think I would like to tackle a rebuild of my engine. With the exception of any machine work (which shouldn't be extensive on a 350 hour engine) I can do this myself. The vision is to build my own Hammerhead. Start with a 3.8 throw crank and 4.0 bore (383) or punch out to .030 over. Keep the 5.7 rods. The key here would be getting the right pistons for around 9.7 to 1, and the right cam for max low-end grunt. The Hammerhead uses Aluminum FastBurn Heads with larger valves and runners than the Vortecs on the Monsoon, but it seems the iron Vortecs are no slouch and are good for plenty of power so I'd prefer to keep those and just massage where appropriate. Not sure if the HH uses a different intake and TB, and it uses some pricy ETX aluminum exhaust manifolds. I think if I just stuck with a new rotating assembly and cam and worked the Vortec heads 375-400 horsepower should be attainable. Then, of course the computer… Flame on fellas!

I did a similar thing with a similar boat (reply 353):

http://www.themalibucrew.com/forums/index.php?/topic/46372-what-engine-would-you-put-in-your-boat/page-18

[OhTwoBu]

Wheeler,

Thanks for the info, can you share any specs? 3.8 or 3.75 throw? 5.7 or 6.0 rods? The work you did to your vortec heads? How does the factory cam handle it? I'm liking the idea of a zz4 cam (208/221 @ .050) with my vortec 64cc's. My thoughts are:

383 crank with 3.8" throw

stock 5.7 rods

still unsure of the pistons to get the right quench

zz4 with factory vortec heads and 1.5s

factory exhaust and intake manifolds

Thoughts?

[WheelerWake]

Wheeler,

Thanks for the info, can you share any specs? 3.8 or 3.75 throw? 5.7 or 6.0 rods? The work you did to your vortec heads? How does the factory cam handle it? I'm liking the idea of a zz4 cam (208/221 @ .050) with my vortec 64cc's. My thoughts are:

383 crank with 3.8" throw

stock 5.7 rods

still unsure of the pistons to get the right quench

zz4 with factory vortec heads and 1.5s

factory exhaust and intake manifolds

Thoughts?

My rotating assembly was an Eagle kit with 5.7 rods, 3.75 stroke crank .030 over Keith Black hypereutectic d-cup pistons. I kept the stock cam (with the 1.6's on the intake) because I was not really after max hp, it will rarely see 5000 rpm. I was trying to make a good, low rpm, combo for use with ballast. The stroker crank should help this. My quench ended up at .051 with the stock deck height and a .039 stainless gasket. The d-cup (reverse dome) pistons make full use of the quench.

I think stock rods have clearance issues with the block and camshaft so I went with eagle SIR's. You still have to clearance the block though. I also had to clearance the block and oil pan for the rear counter weight near the oil filter. And used washers to space down the windage tray.

Stock intake and exhaust.

The crank was an internal balance version. Since I used the stock, eternal balance flywheel, the machine shop had to drill a couple of deep holes in the rear counterweight. This doesn't really effect anything though. Eagle didn't have a front internal/ rear external crank, I think Scat does though.

The porting I did on my heads was all within .75" of the valve seat , removing/smoothing the lip left from the factory machining. Each head is a little different because of core shift. And didn't touch the short side radius.

Because of the low rpm (<5500) nature of this engine, I think the Vortecs flow plenty.

Only have about an hour run time on the lake so far, haven't really tested loaded yet.

Edited December 30, 2013 by WheelerWake

[OhTwoBu]

Good deal, what engine and cam spec was factory for your 2000? The cam is tough to figure out, and the vortecs can only handle limited lift anyway. I'd like to run a zz4 or zz383 (Hammerhead) cam. I'm like you, looking for better deep water digs and mid-range power.

[Woodski]

@OhTwoBu: I put this combo together and really like it, difference being I was targeting slalom and barefoot applications so one item that is very important to me was lightweight parts, thus an abundance of aluminum for my build:

Standard bottom end as engine only had ~50 hours when I started (it's now ~900), Fast Burn 385 cylinder heads (mine started as a pre Vortec engine thus heads were a must), ZZ4 cam, performer RPM intake, recalibration of the carb (yes, it came with a carb and for the application the carb works just fine and calibration is very easy, only drawback are cold starts), 11 deg BTC timing > 33 deg BTC @ 3500+ RPM, Stainless Marine exhaust manifolds and a home made 4" diameter exhaust system w/ H pipe and 4" stainless tips.

Results: significant power bump, much improved holeshot, acceleration (particularly 2-4,500 rpm) and big bump in top end. Great idle with the ZZ4 cam with excellent out of the hole performance. I had to change the prop as it cavitated after the updates were made. With all that, one thing to remember as I was building my setup, the boat was getting lighter and lighter along the process so it does not take that much grunt to launch it so my cam choice may not be ideal for you if you ballast your boat. If I think about the contributions - heads #1, exhaust #2, cam #3, calibration #4. I would certainly consider the standard GM marine cam (what you have now) with some 1.6 rockers as an option.

Edited December 30, 2013 by Woodski

[OhTwoBu]

I think you're right, maybe stock with 1.6s would help. Are you concerned about water reversion with the zz4?

[OhTwoBu]

Looks like just 1.6s on the intake side without machining down the vortecs like Wheeler said. .287x 1.6=.459 but .300x 1.6=.48 on the exhaust which looks to be too much lift in stock form. This is assuming the Monsoon factory grind is a .287"/.300" with a 196/205 @.050 and an LSA of 109? Check? Any more and the seals will have to be ground, not a big deal for a machine shop. I guess the question here becomes what is the ideal grind to make a 383 dig in the low-and mid range, with a wide enough LSA to prevent reversion, and how to mod the vortecs to run it. Anyone know what the HH grind is? Same as an off-the-shelf zz383 from GM?

[Woodski]

@OhTwoBu: Cam assumption is correct for the GM Marine cam, and no I have not had any reversion issues with the ZZ4 cam. I did a fair amount of checking before buying as the elbows are a separate part and you can get/specify what you want for the location of the water inlet on the elbow. The guys that make the exhaust manifolds, if you choose an aftermarket supplier such as Hardin / Stainless Marine / Imco, etc. have a fair amount of experience setting them up. Much more big block experience than small block although there are a lot more options now compared to when I did the upgrade several years back.

[WheelerWake]

I used the 1.6's on the intake only because this was a low buck build, didn't want to change valve springs/machine the heads. Used stock stamped type rockers. I went through all the same decisions you are going through, aluminum heads, bigger cam, even a 454, but in the end less $ won out.

This was my 1st Chevy build, didn't have any spare hot-rod parts laying around.

[OhTwoBu]

I gotcha. I really feel that my vortec heads with the little 170cc runners combined with a 383 short block would make one heck of a stump-puller. It seems with just some simple machining to the seats with stronger springs is all it would take to run a little more cam. I'll probably keep the exhaust manifolds, so need to nail down a cam with no overlap but enough lift and duration to make the project worthwhile.

[WheelerWake]

I gotcha. I really feel that my vortec heads with the little 170cc runners combined with a 383 short block would make one heck of a stump-puller. It seems with just some simple machining to the seats with stronger springs is all it would take to run a little more cam. I'll probably keep the exhaust manifolds, so need to nail down a cam with no overlap but enough lift and duration to make the project worthwhile.

Yep, the cam really defines how the engine will behave, cubes define torque, heads define hp.

[OhTwoBu]

This all sounds like a good plan, the issue once its all together is making it run correctly. Two glaring issues: MEFI tuning and fuel delivery. Does the HH use the same type fuel rail/injector setup as the Monsoon with heavier injectors? I wonder if I were to get the tools from mefiburn.com and burn a stock HH tune if it would be close? Sigh, this sure is stacking up…

[WheelerWake]

This all sounds like a good plan, the issue once its all together is making it run correctly. Two glaring issues: MEFI tuning and fuel delivery. Does the HH use the same type fuel rail/injector setup as the Monsoon with heavier injectors? I wonder if I were to get the tools from mefiburn.com and burn a stock HH tune if it would be close? Sigh, this sure is stacking up…

You could go the way I went, boost the fuel pressure and fine tune it with a wide band O2. My initial testing looks like its going to work.

[OhTwoBu]

What do you think about this?

Comp HR206 cam

206/214 at .05, 112 LSA, .479/.498 gross lift.

The vortecs would need the seats taken down, and better springs, but this seems to be the perfect marine stroker cam

[justgary]

Will the injectors spray properly at higher pressure? Is it better to just get higher flow injectors to make sure the spray pattern is good? MEFITuning.com also has a reference page for those, ranging from 30 to 96 lbs/hr. Oops, I just read the rest of the page, and it looks like a 33% increase in pressure (to 58 PSI) gets a 15% increase in flow (to 57.7 lbs/hr) on a 50 lb/hr injector. I guess it depends on just how much flow you need.

- Just Gary

P.S. At the same RPM as the stock engine, HP is essentially torque since HP = RPM * torque (plus a few pesky unit conversions). For this application, maximizing low-end to midrange torque makes a lot of sense. Forget about peak HP. You'll rarely want to run it at WOT anyway.