350 mag mpi engine upgrade options?
 

I have a 2004 21 lightning with a 350 mag mpi & bravo 1 setup. I'm looking for options to get more speed out of the boat with possibly an engine upgrade. The current motor only has 200 or so hours on it and runs good but just not fast enough for me anymore. I played with alot of props with the help of Brian at Valley prop in Ventura and I'm where I need to be RPM wise (4800 - 5200) 17 - 19 pitch. The best I've seen out of the boat was 55mph with 3 people and low on fuel. Most of the time I run around with 5 people, somewhat loaded down, a big stereo system and hit about 51mph.

What are my options with wanting to stay turn key and reliable? I've heard some people mention whipples and prochargers and also had some people mention the 383 stroker upgrade engines? I'd love to see the boat run 65 - 70 or more.

My mechanic has looked over my current motor many times and says there is absolutely nothing wrong with it. I just need more horsepower I guess to turn a bigger prop to get more speed?

I talked to one of the builders of these boats (John West) and he said I should be able to run a Merc High Five 21p all day long at 60mph. I tried this prop first, could only pull 4200 RPM at 50mph and it was a dog out of the hole. Currently I'm running a 17p 4 blade Solas.

I have not had the engine put on a dyno, I don't know about place around me (Ventura County, CA) that has one.

Any advice without breaking the bank?

Sell the smallblock, and buy a bigger motor, it'll end up quicker, and a lot cheaper than trying to mod your current motor.

heads-cam-exhaust-intake. you will get about 100-150 hp. boat will do 10 to 12 mph faster. engine won't last 1 season. if u wanna go 70, get a big block...

[QUOTE=dereknkathy;3837900]engine won't last 1 season.QUOTE]

Can you explain this statement?

You need an additional 250-300 horsepower to reach your 70 m.p.h. goal. It would make better sense to me to look for another boat with the performance numbers you desire. A 27' Fountain with a big block would hit an easy 65-70 bone stock. While I'm sure you could build a 500-600 h.p. small block (454 stroker motor with supercharger) and reach your goal with your current boat I think the tab would be huge and the motor would need 92 octane fuel and lots of attention.

I was able to gain an additional 12 mph out of a modified small block (350 converted to a stroker) with a much slower and heavier hull. This motor is still going strong and for more than one season.

I don't think I can get much more unless I really get radical on the cam & compression which would then hamper driveablility.

To get to 70 you'd want to get a big block. This is probably your best route.

You have the Bravo so drive capacity is a non issue. Look for a 6.2 marine take out and tweak it to 450~500 horsepower and about the same torque numbers...and torque is where it's at in a boat.. You won't be adding any weight and will have tremendous potential. If you shop hard you can find one for $2K~$3K complete. You could put the same $ in that 350 and see 400+ # of torque but that's not enough to put you where you want to be.

A big block in a boat that size is always going to be ass heavy...period. I have seen it done in F3 Formulas with success but they won't run 70 and with the extra weight in the stern they become a handful. This is my suggestion if you want to keep the boat.

As Wes suggested...dollar for dollar you are better in the long run to sell your boat and buy something larger with twins or a stout big block.

like mentioned...pull yous and sell it complete...you cant tune the pcm on that engine to make it worth a chit! if you just want a reliable faster package look for a 496HO with lowe hours on it..that should put you at 65 mph..

I leaned on the 350s in my former ChrisCraft Stinger260. I got a 4-5 m.p.h. increase updating heads, intake, cam with roller rockers, and rejetting the Quadrajet carbs. I also added taller flame arresters and stepped up from 21" clever 3 blades to 23" clever 3 blades. It was expensive times two! (Not sure HOW Trash got a 12 mph increase w/his 350 hop-up...) I now have a 29' Fountain with twin 6.2s. To increase the output of these engines would require a "whole package" as the stock state of tune has a combination of well coordinated parts. This is not my opinion but the opinion of professionals who contribute to this site and build engines for a living. The 6.2s are 20 h.p. stronger than the 5.7 m.p.i. with about an equal increase in torque. They made a high output version of the 6.2s for a time. The rating was between 350 h.p. (probably VERY conservative) and 420 h.p. (a Mercruiser aftermarket build with CMI headers - required 92 octane). If I had a boat with a tired 350 I would not hesitate to replace the 350 with the 377. But the additional 20 or so h.p. is not going to make a huge difference in the performance of your current boat. A hop-up of the 6.2 would require at least 2k in parts (cam & kit, heads, intake, throttle body) plus the rebuild, machining, and labor. If someday I want more performance than my current 29' Fever I'll purchase a faster boat. JMO

i agree,a hp500 is a 200 hp increase and will net you at least 10 mph faster,and is a much better starting point if you want to go up above the 500 hp range,building the small block to produce over 500 hp is just not cost effactive.

It's funny because I wasn't really sure how much extra performance I was going to get since I never got a chance to dyno the motor (lack of $$$). My initial reaction was that of mild disappointment but I've come to realize it was a pretty descent increase in performance.

I'm running a single application (21' production bowrider) and not a twin so it is difficult to make a similar comparison to your setup. Original motor was a 1995 350 Mag EFI/MP rated at 265 hp at the prop. New motor is a standard bore (brand new block) stroker yielding 377 cid. Kept same fuel injection system but installed bigger injectors, new heads, cam and tuned the EFI myself. Looks IDENTICAL to the stock motor but is far from stock. Runs like a charm and lights off immediately. PM me if you want more details.

A supercharger and Imco exhaust will net 500hp, if you make it into a 383 stroker, with small cam change, it would net 600hp.

Dustin,

How much static compression can you utilize on a Whippled SBC?

:hijack:
Sorry for the hijack....

does the 350 mag have cast,or forged pistons?

dustin,i agree but if he went with a hp500,and wanted to upgrade ,by adding one of your kits he would be in the 750 hp range,if he sold his 350 mag,he would not have to spend a ton of money difference for a hp500,and it has much more potential for upgrades down the road.then he would have some leftover money to upgrade the drive after it ****s the bed.:lolhit:

And how much would that cost?

I can't speak for all Merc 350 Mags, but my 1995 EFI/MP motor had a cast crank, and hypereutectic pistons but a roller cam (GM"395" cam 196/206 duration @ .050" ,.394” / .403” 109 LSA). Stock compression was 9.35:1.

My initial impression was that all Mag motors had forged internals except the pistons. Some may have, mine did not and I believe that is the case for most Mag motors.

if you wanna stay with a light weight motor, to keep your hull balanced, check out my roller 383 stroker in the swap shop. it's 450hp, built right, tons of torque, and also available is a real nice Gil Offshore aluminum exhaust system with long tails. real good price and fresh, runs perfect all around. I'm starting a new project with a blower motor and starting fresh, to be honest, I'm surprised I still have it! It's alot of power cheap... not sure if pointing out for-sale items is frowned upon in this section, just thought it was a good fit for what you're trying to do.

With the exception of the Mercury Remanufactured 383 cu in that is no longer for sale (9.6:1 with Forged Pistons) all the 350s and 377" did not have forged pistons. I could not find any specs on the cranks as to whether they were cast or forged. Cam specs for the 6.2 is: .452/.465 lift, 214/220 @.050 duration (Same as CRANE 2032)
Rpm range 2000-5500

There is your easiest solution. Keep your original engine when you go to sell the boat or use it to finance the new motor. With that size hull You should see about 8-10 mph per 100 hp

This is the stock bottom end of 350 MPI after four seasons and about 350 hours running a Whipple with 4.5lbs boost with LOTS of continuos WOT and higher rpm cruising under boost. Rich enough to be safe but not so rich that it's washing the cylinders down. No signs of detonation either. Stock Hyperucrackedit's are doing fine at this power level with a safe tune from Whipple.

what kind of hp did it make and what was max rpm

What Dustin said, I had Bob @ Full Throttle Marine rework my Merc 6.2 a couple years ago
Aluminum 2.02/1.60 heads, dropped compression down with fordged dished JE pistons, a slightly larger cam/ 1.6 full roller rockers, Stainless Marine Exhaust and 6 PSI from a 2.3 liter Whipple dyno'd at 600 HP @ 6,000 rpms and 575 TQ starting at 3,000 RPM, cheap? No, but I picked up a solid 20 MPH to 90 MPH in a Donzi Classic 18 and the acceleration and looks on people's faces when we go by is priceless, I cruise at or around 3,000-3,200 RPM's and it quit efficient actually. Get with a good builder and they can hook you up on a conservative build that will make your boating experience nite and day different if you choose to go with a little boost, I'm glad I did its been a complete blast!
I believe the SB mag motors are cast pistons and cranks, the 6.2's had the forged cranks and cast hyper pistons least that's what mine had, we reused the crank, I wanted to get away from the hyper pistons and go with the forged while we where in there we went .030 over so it's a 383 now
Steve

What was your static compression and cam specs?

What size injectors did you run?

I believe the compression with the dished pistons was 8.8:1 if I recall might have been 8.6:1 think final was around 12.4:1, as far as the cam I believe it's a mid 230 duration low .500 lift don't have the card on it, injectors? It was a standard 6.2 kit with 2 additional injectors added. Give Bob a shout at Full Throttle, I've been very pleased with it. Forgot to mention the 350's and 6.2's don't come with any oil cooler and a small 4 qt pan, so we also added a 7qt pan and medium size cooler.
I've got around 130 hrs with the blower and last scan less than an hr was above 5,500 it mostly sees 3,000-4,000 when not idling in and out of no wake zones, I can tell you full boost comes in at 4,800 cuz it feels like it shifts into high gear and its off 50-85 happens in a matter of a couple seconds, literally pins you back in the seat, it's a hoot, the fit and finish of the Whipple is really a very nice piece, in my application I had to stay Smallblock and I wanted something that didn't require a scoop and there was no room for the procharger, and personally I love the polished rooter sittin on top of the engine, let alone the whine it gives off under boost. :)
Ill add this mine has the Merc ECM555 and I wanted to stay with the computer, some will say no one can tune them, that's simply not true Dustin did mine and its a special tune for what changed on my engine.

I have 6.2s and down the line I could see myself wanting to push them a bit. If you don't mind me asking, how much did that setup run you? Everyone always says BBC is cheaper but I would like to compare numbers.

Trying to keep all the upgrades mentioned straight. I have a 2010 Nordic 22' EVO that I want to keep SBC and MPI so I'm trying to search out my options.
Of course Whipple is one but they are upwards of $7000! I'd think heads, cam, exhaust and re-flash can be done for much less $$

I did the upgrades and unless you do the work yourself....Whipple is cheaper

If you want a big change go with boost. I went with bigger cam XM270HR better flowing stainless Manley race valves, Vortec head port clean up and new tune. Gained 200rpm at WOT. I had to go into one motor so modifying made sense, but don't expect big results without boost.

1999 350mag mpi looks to have forged rods, cast pistons and crank.

zoom in on crank
[ATTACH=CONFIG]526568[/ATTACH]

[ATTACH=CONFIG]526569[/ATTACH]

That's very interesting to hear actually.
I added CMI's but didn't net any speed gains. (Yes I tried a bunch of different props)
Looks & sounds great, but I was very disappointed that I didn't pick anything up performance wise.

Now I'm looking to take advantage of the less restrictive exhaust and was guessing head and intake work would be way less than the cost of a Whipple

Look up my 383 build thread. There's just a ton that goes in to a good build. Things you wouldn't expect. You having exhaust saves you a lot, so yes you might be able to get a lot more in your budget.

In doing some reseach I came across Raytek Marine who has a 400 HP Vortec for $3000, a 383 stroker for $5000 and a 500HP hotrod called the Barracuda for $5600. With the Vortek and a ECM re-flash I'd be under $4000...BUT does anyone have any experiance with Raytek?
I did a search on here and there are NO topics mentioning them...I just at that point a guy could simply buy a create engine and swap everything over, thoughts???

There is a difference between 400 hp advertised (crank) and 400 hp with accessories on the dyno. Where things got expensive for me was buying the best internals to make the power and insure it would keep living. Going cheap gets expensive.

Your from Milwaukeish, have Mell from C&S build you the motor you want. Before you do any mods, put a A/F gauge in and take a video of your tach and A/F gauge to get your current tune. Plan on buying MEFIBurn and spend a few days playing.

If you are serious-
383 H-beam, forged piston and crank kit - $1800
Big aluminum heads - $1200 (more if you get anodized)
Roller cam - $300 (should be able to reuse your roller lifters)
misc - $600
balance, assemble and machine -? $1200??
Mefiburn - $600

Total $5700.

You ABSOLUTELY need a new intake if you want to make power. My next mod is probably a bigger throttle body too, losing at least 15 HP and a few hundred RPM with the stock one.

All this said, I love my 383s, they pull like crazy up to red line. Totally new boat after the build. I would do it again in the same situation. Unless someone had some semi-fresh 496 HOs sitting around for 20k.

osur866 - What brand is your 7 quart pan for your 6.2? Source?