454 to 502 repower suggestions
 

Though the 454 in my Rinker 236 runs well, I'm trying to get my ducks in a row for when it comes time to repower. Probably going to go with a new base 502 engine (435hp) from 1800runsnew.com. I need suggestions for an intake manifold, carb, electric fuel pump and headers if you guys feel aftermarket headers will benefit the 502 compared to the stock 454 manifolds. The boat also has Captain's Choice exhaust. The boat runs an easy 60mph with the stock 454 and Mirage 23p prop with 4 adults and a full tank of gas. Any guesses on what top speed would be with the 502?

I have a question. If your going to spend $6K on a long block why not get one from one of the builders on here that can get you an extra 200HP for roughly the same investment? I recently rebuilt a 454 for a customer that made 40 more HP than thier base 502 still using penut port heads.

If 502 is what you want go for it. I'm just curious.

Why dump the money into a block where life ends at about 500 inches compared to one where life begins at 500 inches? The 502 gives me room to grow if I so choose. I'd rather pull my original Merc 454 out as a running mill and stick it on the side and start fresh with a 502 that has a forged rotating assembly right from the get go.

I am guessing 3mph. You better plan close to $8k after you buy manifold, carb and what ever else you may need. Most new 502's come with a fuel pump boss, but no lobe on the cam. I took brand new 502's apart and put Bob Mandra cams in with lobes for the fuel pump. Been there done that times 2.:eek:

If the block has a mechanical pump provision, it would definitely make sense to go with a cam from Bob with a mechanical pump lobe.

Can Bob M. build it , yes he can !!! Take all the worries out of it and give him a call , you'll be pleasantly surprised and money ahead !

I would ask Gordon (smokin gun) about 1800runs new. He had a horror story about them and I would believe every word he says about the experience.

OK, that's what I was looking for. I hear people wanting to upgrade to a 502 because they think that is the only way to get more power.

Your chances of getting a long lasting, trouble free reliable engine from 1800runs new is probably 50/50 from what I have read.
Lots of threads on here about them

Is that in regards to their rebuilt engines? If I bought an engine from them, it would be the new base GM engine. I should be fine with a new engine since they are the supplier, not the builder of the GM 502s, correct?

I did exactly this because I didn't listen to the advice given on this board, I gained a few MPH and have zero hours but that's it. If I could do it over again I would purchase a 500 hp custom motor from a builder on here.
The small jump in horsepower from a stock 454 to a stock 502 is not worth the money or effort.
If you have a chance to work with a reputable builder (not an internet engine company) you will be building a relationship going forward which can be very valuable for the long term

Depends... Warranty is only a word unless they are willing to stand behind it

This is why I'm researching repowering now. So when it comes time, I'll know which way to go.

I went with Reher-Morrison power in my race car (980hp 565 BBC). Did it right the first time with the race car. Doing my research now in order to get it right the first time with my boat as well. I appreciate all the input, guys. Thank you!

Yup. A good amount of other people have too. On new motors 'GM Marine' engines also.Check here and other offshore forums. You'll find the crap.

Its not a small jump in CID first of all. If you have a Gen v or 6 454 and its a mag. take the 4.000 stroke crank, 7/16 rods, oil pan and get a 502 block. build a 510-515 CID engine, put some Dart Iron Eagles on it or buy some AFRs and a cam from Madara. New pistons, resize rods new bolts and build a 630 hp package with a carb or EFI. You just have to do it with the correct parts and the right person doing it for you.
I took some 502 500 HPs that were shot!! Lifters had wheels falling out as they came out, intake off a car that was at a angle, threw the heads away and used a set of Iron Eagles, that were new, that someone else completely cobbed up and had to install new valves, valve job and spent time working the chambers and bowls. Called my cam Guru, Madara up and we set up a hydraulic roller. These engines were put in a 41" Sonic, 606 lbs torque@ 4400 / 631 hp@ 6000, think I used a Holley 900 cfm, Daytona Sensors control box and the Thunderbolt distributor. Real simple and cost effective.

[ATTACH=CONFIG]528088[/ATTACH]

This is a dyno sheet from the build.

Great info and got damn great sheet !

Power is obviously great for what the motor comprises of, but, more importantly to me is.....

You know how long it's been since I've seen and honest and 'stingy' dyno sheet posted on the internet ?

You gave the customer what they deserve - a good motor for their $$$$ and the truth of what it will do for them.

Thanks and keep doing what you are doing.

SB, I really appreciate; your comment.
I myself; would always like to build a package with high quality, top shelf parts, who doesn't? It's like Christmas, opening up boxes, not having to deal with dirt, rust and the clean-up. It comes down to the experience level, what will work and what parts will jeopardize dependability. There's something nobody wants to hear; hey your stuff is junk and you need to throw it in the trash. Some clients want everything brand new as long as it's not a waste of money, peace of mind along with some type of warranty. All of us work hard, for money and gratification of accomplishment, if it wasn't for the accomplishment, aspect I would probably be out of this business.
This includes customer relations, mostly which I refer to as friends. Guys like; Madara and Haxby which we speak almost on a daily basis. Some of the OSO members have called me on the phone for help at times. Borgie and I have conversed numerous times. You kind of get to know people, even if you have never met face to face. Just think if it wasn't for the internet, what would we be doing today discussing boats?

Search for the ZZ502 threads on here. Good quality motor that needs very little to go boating. Long block from about $7600

That is definitely a good option.

Eddie, you have been given some very good advice from some guys who know their stuff so far. I too have talked to Mark on the phone, and he is an extremely knowledgeable guy who is generous with his time, even if he has nothing to gain financially from it. I can speak highly of Bob Madara as well - another respected guru who is generous with his time and info. There are quite a few "good guys" who post pretty regularly on here. Maybe you can find one who is convenient to you geographically to build something that will suit your needs. Also, look into what shipping would cost - some of these guys might be able to build you a turn-key long block or complete engine that has been dialed in on the dyno and is ready to drop in.

Before doing this, step back and assess your situation with your current boat. What are your goals with it, how much do you want to spend on it, and how will you use it? On an older boat like that, you can pretty much figure on not getting much if any of your investment back if you were to sell it. My situation is the same - I would have to part the boat out or put stock running gear back into it to recoup any of my investment. Keep in mind that 600+ HP is going to tax the limits of your drive, and hitting speeds like that would make hyd steering a wise investment.

If you are just looking for 8-10 MPH improvement on the top end, why not consider building a stroker 454 (489 - 496 cid)? That's what I did. Good Gen VI 454 cores are easy to find and relatively cheap. MK IV blocks are plentiful too. You can get pretty decent quality complete stroker reciprocating assemblies with good forged pistons, crank, and good rods for less than 2K. Or you could find a good used 454/502 steel crank here on OSO in the Swap Shop and stay with a 454 cid. You could easily top 500 HP with the right combination of heads and cam. Bob is definitely a good guy to talk to about cam/head selection. Once again, you have to decide what you want to do with the boat/motor going forward. I'll warn you that it's a slippery financial slope - you can get caught up in the horsepower hysteria and find yourself spend 2 or 3 times your original budget if you are not careful. And above all, listen to the guys you talk to and spend a little up front to put the best parts into your build - especially the valvetrain. You DON'T want to do this twice - trust me, I know!

This is good advice. Regardless what a vendors intentions are, the fact is a lot of things start changing as you near and surpass the 500 hp level. After you spend $ after $ on nice lifters, springs, etc. and enough exhaust to run it all, now you have to treat the drive like its a stock motor and you will still be fixing them. Even with a well thought out motor, your chances of issues rise considerably over say a stock 502 mag that will run for a decade + with just oil changes.

Thanks again for all the input, guys. Truly appreciated!

I primarily use this boat on a 5,700 acre lake here in the Pocono Mountains. The lake is only 15 minutes from my house, so I use the boat often. I also would like to do a few poker runs next year. As stated earlier, the boat easily runs 60mph with several adults on board and a full tank of gas. I believe there may be a couple more MPH in her if I took the time to play with weight distribution and trim positions. The engine runs flawlessly. I'd like to pull it out and build another engine versus building this one. While I plan on keeping the boat for the foreseeable future, if I do end up selling it, I'd like to keep the built engine to possibly use in a different project/boat and stick the stock Merc 454 back in the boat to sell. That gives me the option of reusing my investment instead of selling it with the boat and losing more money.

I am open to having a custom engine built, perhaps a 540. I'm not dead set on a GM crate engine. Trying to weigh all options. Though older, the boat is in very good shape and doesn't owe me a dime, so putting a few bucks in her doesn't hurt me. Yes, I have also thought about drive limitations if I choose to go with big power. I've read of some guys getting their Bravo 1 drives to live under big power by eliminating air time and holeshots, etc. I've also read of other guys killing their drives with stock 454s. While I do enjoy the occasional 60mph blast, I don't beat on the boat. If I do go with a custom 540, I'll do what I can to extend the life of the drive and take the necessary precautions.

This leads me to another question. What do you guys feel the boat should do, top speed wise, with a 600-650hp 540 assuming it has the right prop?

Bumping this one. Would a 15mph increase seem reasonable given the right prop?

I want to repower a Formula 400SS from 502MPI to .8.2L or 8.1... one of my quotes said the following:

Things to keep in mind, I have been told by Mercury Tech Support (on another boat) that the entire package (engine, transom assem, and stern drive) must be seacore to get the 4 yr corrosion warranty, so only having the engine be seacore you wouldn't get the extra corrosion warranty. This option is for a non DTS (digital throttle and shift) package. Also a non ECT (emission control technology) which means you must send back the engines being removed in a complete form.
There is a 430hp option in an HO (high output), which adds about $13k extra horse power is expensive. In this option we would need to look into upgrading the out-drives as your current models will not take over 400hp. There are also options to install smart-craft gauges, DTS controls, ECT (if you don't want to send back the old engines) shoot, we could install Axis with joystick piloting if you want. Many things to consider.

any thoughts on the above..?

Thank you ..