350 Mag performance upgrade suggestions
 

I own a 02' 29 foot lightning with twin 350 mags (300 horse). Are there any reliable bolt on accessories to boost horsepower and keep reliability?

Re: 350 Mag performance upgrade suggestions
 

Unless you consider heads etc. bolt on, or if SC is an option, the 350 MAG is the same as any 5.7 but with a better fuel system which gives it the extra HP.

My guess is to get anything substantial you'll have to tear it down to some degree and at least do some head work, new cam etc.

Re: 350 Mag performance upgrade suggestions
 

If you're willing to ditch the factory EFI and go with an aftermarket system or carb you can get another 75 HP (per engine) or so naturally aspirated. Otherwise leave it alone. More than that, put a pair of Whipples on it.

Re: 350 Mag performance upgrade suggestions
 

Whipples and headers.

Re: 350 Mag performance upgrade suggestions
 

Start by doing yourself a favor and replacing your stock exhaust with Stainless Marine. I just put some on my 28 Cig and I really like it. It's lighter, looks better, sounds better, and makes more horsepower. They have a 5 year warranty and it will cost you less than 4g's

Re: 350 Mag performance upgrade suggestions
 

sc's, cmi"s :D

Re: 350 Mag performance upgrade suggestions
 

Agree with everything said above or you might consider swapping for a pair of 496 HO's if your wallet will allow it... Then you'd have big block torque, a lot more hp and excellent dependability... :D

Re: 350 Mag performance upgrade suggestions
 

I would do some checking with Mercury because I was told by a boat builder that the 350 MPI's were listed at 300 but are actually 275 and that Mercury has upgraded it's brain on the new engines so they are 300 HP. May be worth checking into nay be a cheap 50 HP.

Re: 350 Mag performance upgrade suggestions
 

Where would you check into this extra 50 HP from the 'brain box'. I know that snowmobiles are totally different, but you can have the ECU reprogrammed by racers(who send them to the manufacturer) for an extra 15hp or so. On a sled, this is a huge difference. The problem that you run into on a sled, is that by reproming the ECU, you also are running a risk of less engine life, or restricted to diff. fuel, or just making the motor good for short runs/bursts. I would think that if it was that easy, to just send in the ECU(or whatever it's called in a boat), and gain 50 HP, everyone would be doing it. Someone please prove me wrong...I would do this in a heartbeat if it was possible! Someone on here has to know where or if something like this can be done, and if it is safe. Thanks, J.

Re: 350 Mag performance upgrade suggestions
 

I just got off the phone with a large aftermarket retailer in CA, and he said that you could gain about 15% more HP by remaping a stock ECM on a 2003 350 mag mpi. He made it sound like it there was really no big gain to be had by just doing that. I think he was contradicting himself because to me, 45HP for $400 is pretty cheap??? Is he blowing smoke?

Re: 350 Mag performance upgrade suggestions
 

Prochargers..... I am installing a set on a twin 350 mag mpi motor now, should have some numbers in early march.

Re: 350 Mag performance upgrade suggestions
 

Does that mean your not selling it anymore? though I just say a post saying you were?

Re: 350 Mag performance upgrade suggestions
 

I don't care either way. I have the boat and the prochargers, gauges, props etc. I love the boat and it could not be replaced with anything else for the money I would sell it for. The chargers are still boxed up (since christmas). I am finishing up a 57 vette job before I tear into the boat. Hopefully in the next couple weeks. We have been looking at guns and hustlers here lately.

Re: 350 Mag performance upgrade suggestions
 

I made more calls this afternoon and can't get a straight answer about remapping a stock ECM for a 350 mag mpi as mentioned above. Does anyone have any suggestions?

Re: 350 Mag performance upgrade suggestions
 

Tyler Crockett in Michigan does ECU upgrades for 454/502mpi's maybe he does something for the 350s.....just a thought...............doug

Re: 350 Mag performance upgrade suggestions
 

Talked to my dealer today and they called mercury. Nothing is offered from merc for reprogramming. Aftermarket would be the only option.

Re: 350 Mag performance upgrade suggestions
 

How do you get ahold of Tyler Crockett in Michigan? Thanks

Re: 350 Mag performance upgrade suggestions
 

I put a 5psi Procharger on my 99 350 Mag last fall. So far I picked up 13mph but ran out of warm weather before I finished tuning. Sent the ECU off to ASM to remove the rev limiter and set up for a 2 bar map sensor. Now just waiting on the weather.

Re: 350 Mag performance upgrade suggestions
 

What boat? what speeds prior to installation? what prop befor an after? sounds impressive.

Brian

Re: 350 Mag performance upgrade suggestions
 

It's a 22 1/2' Crownline bow rider. Ran just over 50 mph gps with a 19p Mirage Plus and now run a 23p at just over 63. Still had some issuse with timing and rev limitter last time out, should be able to get 65mph with a little more tuning. I have plans for manifolds and higher boost this summer, shooting for 70mph.

Re: 350 Mag performance upgrade suggestions
 

Is this Tom? :D

Re: 350 Mag performance upgrade suggestions
 

Justin- For just about anything you need go to google.com search and type in what it is you're looking for... :D

Re: 350 Mag performance upgrade suggestions
 

It is :D

Re: 350 Mag performance upgrade suggestions
 

Justin: I went through that with my '03 350 mag. before I upgraded to a 496HO. The '03 ecm is the 555 ecu that no one other than Whipple presently has the ability to reprogram. There were rumours, though, that other shops were working together on "cracking?" the code. Maybe Dustin at Whipple can help you; they do offer ECM reprogramming on the 555 ecu on the 496s.

Re: 350 Mag performance upgrade suggestions
 

Air-Gap intake , 600cfm carb, Crane 104224 cam = apprx.360-375hp...

Re: 350 Mag performance upgrade suggestions
 

thanks everyone for your answers to my questions. My boat would need some serious upgrades to be able to put on a Procharger. I have the 350 Mag Mpi, but only the Alpha outdrive. It is a 2102 VIP Victory bowrider. It is a very deep and extra wide boat. It does pretty well for its size I think though. Right now I run about 59 GPS 63 speedo. (I like to go by the speedo number, it makes me feel better :) ) I should probably just get a labbed prop. I am running about 4850-4900 RPM. Right now I have a Ballistic prop. It seems to work well with this boat though. My boat is a little bow heavy. It seems hard to get the lift that I need. Here's a couple pics.

Re: 350 Mag performance upgrade suggestions
 

justin- did you have any luck talking to Tyler Crockett??......I forgot , he is a member here.....If its bow lift your looking for try a Mercury Mirage or Mirage Plus prop.....they offer tons of lift and will fit on your Alpha, though because of the increased diameter of the prop you will have to ditch the stock trim tab (at the end of the cavitation plate) and go with a flush one (its a Merc part)......and you should be putting a Simrek drive shower on that Alpha too if you are up on plane for long periods of time......the increased dia of the Mirage will load the drive more and the Alpha runs hot as it is........I have twin alphas and smallblocks on my boat.......been there.........doug

Re: 350 Mag performance upgrade suggestions
 

Doug, could you elaborate on the trim tab you are talking about behind the cavitation plate? I've been told to go with a mirage plus before, and possibly have it labbed. (Houston Prop possibly) What I don't understand is how you can just order a labbed prop without knowing how it is going to respond to your boat? I suppose I would need to test a Mirage prop, and then try and figure out how much RPM I would gain by labbing a prop. This part you are talking about. Where exactly is this, and how much is it about? I was deifinitely going to go with Simrek drive shower as well. Cheap insurance I guess. We do run wide open on the river quite a bit.
Thanks for your help. BTW, I haven't talked to Tyler yet.

Re: 350 Mag performance upgrade suggestions
 

I had a brain fart. sorry. I think you are talking about the round disk on the bottom of the cav plate. Mine has the flush one already. Thanks, J.

Re: 350 Mag performance upgrade suggestions
 

talk to mark boos from precision marine he did an awsome job of reprogramming my ecu for my 1998 502 efi !!

Re: 350 Mag performance upgrade suggestions
 

Did you get my e-mail Brian?

Re: 350 Mag performance upgrade suggestions
 

Yea I did, I sent you one back this morning.

Re: 350 Mag performance upgrade suggestions
 

blown crown, do you think my boat would work with a procharger? I don't want crazy horsepower, but it sounds like the minimum HP would be about 430-450 and 3.5 lbs of boost. I'm sure my Alpha wouldn't last long, but maybe it would if I took it easy. I prob. wouldn't use the power most of the time. I usually have kids etc. in the boat, but it would be awesome for the quick joy rides! I emailed you also to see what you have invested.

Re: 350 Mag performance upgrade suggestions
 

Justin, I would be very careful with the Alpha, Procharger claims 490hp on the 350MAG MPI with 3.5psi of boost (I think thats very generous).

The kit is around $3500 so you can figure on $4000 as a minimum just to get things running. I've got around $5000 in mine which includes: oil cooler, MSD ignition, fuel press & boost gauges, reprogrammed ECU, drive shower and a hand full of misc. stuff.

I too have a boat with a limited hull, so I know what you are going through.

Re: 350 Mag performance upgrade suggestions
 

Did you have to reprogram your ECU because of the RPM you were running? What problems did you have on installation or anything else? How was tech support? It sounds like Procharger is a little misleading on some things, like no ECU reprograming, no oil cooler needed, etc... for a stock 350 MPI. I just wish there was something with 1/2 the power for 1/2 the money...How did yours handle at top speed last fall?

Re: 350 Mag performance upgrade suggestions
 

From everything I have read you do not HAVE to have the ecm reprogrammed. The difference is that it will run really rich with a black transom if you don't and may not perform as well. You should already have a stock oil cooler. Most people have the ecm programmed for rev limiter reasons.

Re: 350 Mag performance upgrade suggestions
 

You do not have to get the ECU reprogrammed. I plan on running mine at a higher rpm than stock so that was my reason, it ran fine before. Also I do a lot of long high speed runs so thats why I installed an oil cooler.

Installation of the Procharger was very easy, the only problem I had was the inter-cooler flange that mounts to the throttle body was wrong due to the build date of my boat. Procharger got me the correct one in just a few days. I felt like the kit was very complete and instructions were well written.

One of my concerns was that with a centrifugal supercharger you need rpm before you make boost and would not be able to prop the boat for top speed and still get out of the hole reasonable. That has not been a problem with my boat. It takes off like a sling shot and still runs on the top end.

Re: 350 Mag performance upgrade suggestions
 

Thanks for your help. Everyone seems concerned that my hull won't handle the HP. Also my drive is an Alpha, and there is mixed opinion on the strenght of this drive for this application. I am really torn on what to do for now. I do know that I will be keeping this boat for atleast 5 more seasons, and it would be fun to try something like this. Thanks again. Justin

Re: 350 Mag performance upgrade suggestions
 

490 HORSE!!!! I do like the sound of that. Blown crown, what did you do with your drive?

Re: 350 Mag performance upgrade suggestions
 

My drive is a stock Bravo I with a 23p Mirage Plus. The only thing I have done to it is install a drive shower. I may upgrade some of the internals when I up the power over 550?