So it's time for some upgrades.
 

i have had my boat for a year and its fast and no issues, but i think some performance goodies are in order. except for supercharging what are ya'll doin on N/A boats. I would suspect cam and heads, but thats why i'm here to find out

:cool:

Probably going to need to know what you're looking to upgrade.

If you have Sterling 1200's, you're probably good to go. If you have Merc 330's, you need to start from scratch.

If it's something in between, common upgrades are heads, cams, manifolds/carbs and the typical biggest bang for the buck, exhaust. Each thing you do can cause a ripple effect downstream- big cams need more intake, heads and exhaust. The also strain the bottom end more- sometimes you need stronger components altogether, sometimes just bigger coolers and oiling system mods. That same big cam may necessitate roller rockers & girdles- and probably stronger pushrods. Then you have transmission and outdrive issues- if your Merc 330 is on an Alpha, you have real problems. If the Sterlings are on 6's... ;)

What engine do you have right now and what is your budget?

sorry thats important its 502mag 415hp mpi stock bravo 1 25p prop. the engine is completely stock from flame arrester to exh manifolds. i was thinking exhaust, but wanted to make sure thats a good starting point. also do you have to reflash ecm after exhaust?:cool:

Budget?

Exhaust
Cam
Aluminum heads - AFR315's would be nice
Re-program ecm, possibly larger injectors, bigger fuel pump, etc.

i get this right sooner or later bout 6500.00 for now :cool:

How many hours on the bottom? If it's in the 300-400 range, adding a bunch of power may drastically shorten it's life.

In that cost range, I'd add a cam, manifold, carb and exhaust. You can probably find a nice set of exhausts on the used market. Cam- probably a Crane 731 or something thereabouts- with Morel hydraulic rollers. A good cleanup on your heads with better valves will give you plenty of flow- aluminum heads will give you a few ponies more but not the best return for your buck.

Save some money for a good engine oil cooler, a drive shower (assuming you have a Bravo) and a new prop to take advantage of your bump in power.

bout 450 hours or so, got a drive shower tell me about oil coolers dont have one of those. i would like to make 80-82 mph by the gps

At 450 hours, I'd want to pull the engine and freshen it up. You're doing a good sized chunk of it anyway- another grand for pistons and a bore is a very worthwhile investment. Have the rods rebuilt with a high-quality rod bolt.

Oil coolers- you'll need a remote adapter to take the oil out of your block and thru the cooler. You might as well add in a remote mount pad for the filter- makes changes so much easier when it's right up top. The oil cooler will go between your water in and the engine and route oil through it. With these mods, you'll need to add an oil temp gauge and a water pressure gauge. No sense smoking your new motor.

Here's all you'll need to know...
http://www.offshoreonly.com/forums/s...3&page=1&pp=20

i have a factory remote oil filter already on the boat. that thread is money, thanks dude. so just build it like you would a street car, heads cam etc. what am i looking for in camshafts?

First, I can't emphasize enough that you should read that thread on oiling and follow everything in it. It'll mean your motor will live much longer.

On building the engine, it's nothing like a street car engine. The loads on a marine engine are constant and non-stop. Think NASCAR with the addition of continual loading & unloading of the driveline. Any and every thing you can afford to do to bulletproof things will make your engine live. At a bare minimum I'd use an SRP piston. TRW's and pistons like them just won't last they way you'd want them to. KB's and other hyper-casts are a waste of money here. Prep and blueprint makes a world of difference. Clearances are critical. Depending on your cooling system, your cylinder clearances are going to be 1.5 to 3 thousandths larger- or possibly more. Valve clearance is critical too. Street clearances will cause your exhausts to hang and hit the pistons. That's a bad thing. Stainless valves are the minimum. On cams, it depends on your exhaust. Do a search on "reversion" This is a phenomenon that pulls water back into your exhaust ports due to cam overlap. if your exhaust mixes water too close to the heads, you need a fairly mild cam. If you want horsepower, you need dry tails or at least tails that mix very far out. in case you didn't catch it, reversion is a motor-killer. Cold water on hot exhaust valve heads causes them to pop off and put holes in your pistons. Don't get crazy with heads. Big rectangular ports that flow big on top have lousy mid lift velocities, especially at low and mid rpm. Your boat won't be much fun if you have to change the plugs every time you hit a no-wake zone. Also, if you're realistic, you'll recognize that you spend your time at max RPM a very small amount of the time you're out boating. You need that midrange- don't give it away thinking you'll be going mega-fast all the time. I've seen motors that dyno'ed big that didn't have enough low-mid to pull the boat on plane.

:D
If it aint broke dont fix it!!!! If its fast and has no issues thats the best kind!!:D

i know but the hot rodder in me is wanting more and few bolt-ons for now can't be all bad. besides as i found out in this thread its gonna take rebuilding soon(as she does puff "chevy smoke" first start of the day) before any serious upgrades are made. i do see your point:cool:

chris

thats kinda the answer i was looking for clearences, reversion and all that type stuff that is boat related. i have built engines for years for all my toys but this is all new different principles apply. thanks for help:cool: the oil cooler thread was eye opening

luke

Just keep in mind you're building a completely different type of engine. Take a look in the general tech thread at some of the recent oil pressure discussions. There have been alot on HV, HP HV/HP vs. stock oil pumps and the upsides/downsides.

On your engine- if it were mine, I'd bore the block 30 over and put SRP flat-tops in it with the JE rings. If you compare, you can get SCAT rods with good bolts and bused small ends for about what it'll cost you to rebuild your stock rods- that's the way I'd go. I just bought Manley's on Ebay for under $400 a set so watch there too. Since you're probably aiming at about 550 horse and a broad torque curve in the 575 range and a max RPM of about 5600 or so, I'd stay close to stock bearing clearances on the mains & rods and a blueprinted standard-volume pump. That should gove you 60 PSI running. On top, I'd do a bowl cleanup on your heads and install manley severe duty's in them. On cam, I'd talk to Bob Madara (RMBUILDER on the board) and have him grind to your application. It won't cost you more and will probably save you a few bucks. The can he gives you will probably look very similar to a Crane 731, but it'll be better. Morel roller lifters are a necessity. Bob will send you the right springs. Roller rockers are a must. I like the Comp Cams stainless for the RPM range were talking about. Depending on your hull, you may want to stick with a good dual-plane. A light boat could be tolerant of a single-plane a bit more. Top it with a Holley HP 950. Buy it from Nickerson and they'll send it to you tuned, tweaked and jetted- ready to bolt on. On exhaust, you're going to be hard-pressed to be the Stainless Marine for price/performance. Eickerts are excellent as well but more expensive. If you can find a nice set of Gils you'd be OK there too. On ignition, you probably have something you're comfortable with but I'd look at either the marine versions of the MSD 6 and the Crane Hi6.

yeah 550 is about the number. i think i will keep the mefi, of course with the correct injectors fuel map etc. its a little bit expensive to keep but if i want a cheap sport this ain't the place to be. i will start my search for engine hard parts and get ready to pull her this winter. i am going to upgrade oil cooling system before summer is out...

Yeah, I missed the MPI. Can't help you on that one- I'm a carburetor guy. There's lots of tips to be had on injection- I'm sure someone will weigh in.

well mpi i got handled except for the marine aspect of it. so those 502mag heads will do the job with some work that will save some money.

Those heads should be 088 or 990 castings- both will do very well with some mild bowl work and a 3-angle valve job. Make sure to magnaflux them- they can develop cracks between the valve seats.

all right moving on, what about installing livorsi depth gauge shoot thru style. is this a do it yourself thing ( no laughing if its real easy)




:cool:

OK. No laughing.

Glue it to the hull bottom in the bilge.
Connect the wires.
Use.

Don't glue it next to your bilge pump. Bilge pumps are typically screwed to a piece of plywood laminated into the bottom of the bilge. Don't use it on a cored-bottom hull. The signal won't cleanly penetrate wood.

Relax, this one's easy.

thanks dude, your a ton of help



:cool:

What about the intake? ANy suggestions there? Also if he is replacing pistons how about stroking the engine?

Another thought will be to replace the prop and have it labbed. It will get you another 2 mph on the top end. If you into water sprots the current prop will be a good spare and give you a lot of low end for skis and tubes etc

Question, Can I mount my remote oil filter head upside down so the filter can is up?

coolhand, if the engine has been maintained(oil changes reguarly, the bottom end of your 502 is still solid and you should not have to rebuild the whole thing . Your heads need to be rebuilt with springs, keepers, valves, guides, etc with top of the line stuff. Add roller rockers, then put on Gil exhaust and new risers. You can do this for 4000 to 5000. I did this two years ago and it has been good. The key is to have a good marine shop rebuild the heads with the best parts.

she seems tight i have noticed "chevy smoke" on start up and she uses a little during the summer. the valve guides are probably the start up puff so if the cylinders look good i will just upgrade the heads.

BBC's are known to use a little oil. I have had brand new 396 and 454 Chevelles that used to burn the top 1/2 quart within a day of an oil change. I have also had good 454's and 502 marine engines do the same. Unless you want to be a world beater just do some bolt on mod's with exhaust and maybe consider an ignition upgrade, next lo to propping the boat correctly. I think you would be very happy with it after that.

Anybody know if I need anything special? Can I mount my standard filter head upsidedown with a standard filter?

I believe it depends on the filter, some have an anti-siphon valve some do not. Do a search on filters on OSO. I found more info then I was looking for.
jim

hey if you want the boat to run right sell it and by a real boat FIRST ha!ha!
I new you could not handle it. bring it up and I will make it run like a fountain:rolleyes:

here is my suggestion. Sell your running 502mag for 4-6k. Then pick up a good used 500efi or 525efi for 10-15k. You will be in it for 5-9k plus labor. You will gain 75-100 hp, won't grenade your drive and will have the resale value and reliability of factory power . Good luck mike

If your looking for an exhaust upgrade I have a set of stellings (green) 89 bbc 454 502 572 should bolt right up they came off of a 454 running 550hp.