500hps rebuild

[rssteiny]

My 2000 500 hps carb motors have 430 hrs , still run flawless and strong but i want to refresh and power up a bit. what would be the best way to go.

[HolyMoses]

I had the same motors in my 36OL. As long as you keep the valve train fresh every 300hrs. and maintain the motors you should see 800 plus hours with no problems to the internals of the motors. If your looking to refresh them you could do new bearing upgrade the rods, heads and cam and make an easy 550hp to 600hp.

[Griff]

Bump comp ratio up to about 9.25, aluminum AFR heads and a cam change. I would guess about 575hp.

[rssteiny]

What about the bottom end

[Griff]

The rods and crank are fine to handle the HP increase. Just have them polished and reconditioned as needed. The comp ratio increase would be achieved with new pistons.

[Thunderstruck]

Deck the block or mill the heads to increase compression ratio with the stock pistons, rods and crank. Up the compression with your iron heads will gain some hp with little $. I think .01" off of the heads or the block will raise the compression by .1. Also, port and polish heads with new cams can help without expensive aluminum heads.

More $ but AFR heads and RMBuilder cams can make 600+ hp. I made 595 hp with stock rotating assembly. Need to bump compression to 9.6 with aluminum heads. The best I have heard with AFR heads and RMBuilder cams is 640 hp. Need to turn up to 5800 rpm to get >600 hp so you will need new ignitions due to the 500 hp rev limiter. I went with Crane that will work with the stock Merc hall effect distributor. Need to seriously consider closed loop cooling if you boat in brackish or salt water with aluminum heads.

My 1998 AT runs 91 with Gil Exhausts.

Basic freshen job would be new springs, lifters, rings, hone block and crank, new bearings, valve job. New roller rockers may be a good idea also.

We can discuss live if desired. Let me know.

[Offshoredrillin]

I have a set of heads off of my 500 efi that have already been milled to bump the compression up to 9.25. one set is fresh 0 hours, the other has 45 hours....1800.00 for both.

[Griff]

His boat is 100% dialed in with props and carb tweaks and ignition already. The valve springs were done about 200hrs ago.

[rssteiny]

His boat is 100% dialed in with props and carb tweaks and ignition already. The valve springs were done about 200hrs ago.

Yes as griff said it already has msd to override limiter, carbs have been worked, and with labbed 30 props i run 5500 at 84mph. would like to refresh due to hrs being 430 and would like to run 90 mph, and yes springs were done about 250 hrs ago so also time to renew them as well.

[Thunderstruck]

Yes as griff said it already has msd to override limiter, carbs have been worked, and with labbed 30 props i run 5500 at 84mph. would like to refresh due to hrs being 430 and would like to run 90 mph, and yes springs were done about 250 hrs ago so also time to renew them as well.

Your theoretical speed is 101.5 mph which makes your slip 17.3%. That is high. You could get more bang for the buck going after the slip ie making the hull/drives more efficient, than adding hp. I added nose cones to go from 87 to 91 mph. My stock 500 HPs pushed me to 82 mph best. Motor mods got me to 87 (5500 rpm) with 16% slip. Now I'm at 5450 rpm with labbed 30" props at 91 mph which is 9.5% slip with the nose cones. Big difference.

One guy with a 32 AT I talked to had his hull straightened and gained 3-4 mph. Have you checked your hull with a long straight edge to make sure you do not have a hook?

In my opinion, the more hp you throw at your hull/drives, the more slip you will get since you are already at 17%. My problem was that at 87 mph the pressure wave on the front of the nose of the drive case was pushing the water away from the props to the point that the slip went up and killed my hp increase. The faster you go the worse it will get with the Bravo outdrives. Nose cones fixed my issue. The hp to make 90 is therefore a moving target with a situation like you have. I will take much more hp to produce 90 mph at >20% slip than at 10% so take the easy speed and improve your efficiency before turning the hp up.

Based on my 1998 32' AT that runs 91, you will need 585 crankshaft hp on a dyno with no accessories, using dyno exhausts to make 90 mph low on fuel by yourself in the boat. (That assumes 10% slip.) Adding water pumps, power steering, alternator, marine exhausts and the drives consumes hp but my dyno did not have the capability to dyno a fully dressed marine motor. I would shoot for 93/94 to make 90 with a tank of gas, people and gear.

Ambusher, the guy on BoatFreaks has a set of stroked 454's, 496 ci motors that runs 92 or so. He probably has a good bit of hp than me but close so there you have two references with the same boat that indicates you will need close to 600 hp which will be difficult without some head work or new heads and new camshafts and some dyno time.

Nose cones were <$500 doing the work myself. Cheapest speed I ever got.

Once again, PM me and we can talk live. I've been there done that.

[Thunderstruck]

BTW call RMBuilder for the HP possibilities, he is the 502 NA guru for cam shaft/valve train improvements.

If you are interested in aluminum heads, my experience with AFR was/is great. They are some of the best heads out of the box to build a torque monster combined with RMBuilders cams. My acceleration is amazing, ask Clarkstar.

[rssteiny]

BTW call RMBuilder for the HP possibilities, he is the 502 NA guru for cam shaft/valve train improvements.

If you are interested in aluminum heads, my experience with AFR was/is great. They are some of the best heads out of the box to build a torque monster combined with RMBuilders cams. My acceleration is amazing, ask Clarkstar.

Is there a difference in the 1998 32 and the 2000 32 hull. nose cones that is interesting and makes me wonder if that would help me. thanks rick

[Thunderstruck]

Is there a difference in the 1998 32 and the 2000 32 hull. nose cones that is interesting and makes me wonder if that would help me. thanks rick

I don't know if there is any difference in the year models. I do have a notched transom with fairly high drive heights which I would imagine you have also.

Tom

[rssteiny]

I don't know if there is any difference in the year models. I do have a notched transom with fairly high drive heights which I would imagine you have also.

Tom

Yes i do as well, im just asking because if you have the same hull then i may want to try the nose cones, i was thinking that 1999 or 2000 there was a change in the hull but im not sure.

[Griff]

I don't think they ever changed the 32 bottom other than the notch. My '97 does not have a notch, but I have boxes instead. My slip is right around 12% and I do have nose cones as well. The only other difference I have seen in 32's is the slant on the deck at the stern that started in '98, I think.

[Thunderman98]

Tom,
What nose cones did you use. Right now my best speed is 93 radar and that's with 700hp dyno 572 motors at 6000 rpm. I was spinning 30's at 6000 which put me around 18% slip. I did try a set of stock 32's, but popped a drive at 3800 and roughly 70 mph. Im hoping to retry again this spring with the 32's to see what my top speed and slip is. I know we have talked before, but cant remember what you had said.

[Thunderstruck]

thunderman, guess I haven't been watching this board enough and missed your question. SORRY!

Background, I have LWP Bravos with a notched transom and fairly high drive height. In fact my 32 was supposedly the first 32 with the notch. Anyway I called Teague who recommended the "Leading Edge" nose cone that fit the LWP drive. It is pointy, not crescent shaped like a hydromotive cone. Look in the teague online catalog for the model. The drive height has a lot to do with the type of nose cone you need so ask around before plunging in. The sales person at Teague was very knowledgeable regarding nose cones and they let me talk to a shop guy who helped me with the installation issues.

[Thunderstruck]

I couldn't post a pic of my drives with the cones on but look on OSO or boatfreaks. Must have to pay to get pics on on SO or am I missing something?

OK I got it. Didn't scroll down far enough.

[Chris]

No- costs nothing to post pics. You do it exactly the same way as OSO or BF.

[Chris]

On this rebuild project, you can get SCAT kits for under $1800 that will turn those engines into 540's. ATECO is running a sale right now.

There's no substitute for cubic inches and in a boat, there's absolutely no substitute for the additional torque you get with a longer stroke. Stick a set of Dart 320's on them and the Dart manifold and you're set. I'll second calling Madara for the cam.