What would be more reliable merc. 525sc or 502mag w/blower set up?
10-08-2014, 06:39 PM
#3
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Both would need a few things to be the most reliable that they can be.
The 525 sc should really have the cam and lifters changed to a hyd roller. It should also have the blower rebuilt if it has anywhere near 200 or so hours. DMPE can rebuild it with better seals so that the gearcase doesn't become as fuel diluted.
Adding a supercharger to a 502 Mag is an excellent idea, as long as it's done correctly. A Whipple is more upfront money than a Procharger, but there are less mods to do. If going with a Procharger, you will need to throw away their fuel system and replace it, as well as programming the ecm. Everything you need is included in a Whipple kit, including a pre programmed ecm. That's why it's more upfront money. You don't see that many used Whipple kits for sale, because most everyone loves them and doesn't want to get rid of them. Used Prochargers are not that hard to find. You can pick them up for around $2500-$3000. With either supercharger, there are still a few things that should be done to the 502 Mag. You should change the exhaust valves, springs, retainers, lock and seals. You should also change the head gasket to an MLS (Cometic) and install ARP head bolts. Another really good idea is to change the non adjustable valvetrain into an adjustable one. That requires changing the rocker arms and studs to make them adjustable. That also allows you to get rid of the stamped steel rockers and go to an aluminum roller rocker.
When done properly, either can be great setups. The 502 Mag with a supercharger will make from 600-650 hp very easily. That's quite a bit more than the 525 sc. It is also somewhat limited since it's only 454 ci. The 502 Mag can easily be upgraded along the way. With either supercharger, you can step up to a set of aluminum heads and make quite a bit more power later on when you are ready for more upgrades. The little blower on the 525 sc is the limiting factor. You will need to replace it at some point to make any substantial gains. Even then, you are still dealing with limited cubic inches.
Personally, I would go with the 502 Mag and upgrade it as money allows. You can continuously upgrade it as you go. We have made well over 900 hp with one with a Procharger, using the 502 Mag intake. Now, it was 547 ci with aluminum heads, extrude honed intake, larger injectors, etc. but it started life as a 502 mag. You can do the same thing as money allows. Let me know if I can help in any way.
Eddie
The 525 sc should really have the cam and lifters changed to a hyd roller. It should also have the blower rebuilt if it has anywhere near 200 or so hours. DMPE can rebuild it with better seals so that the gearcase doesn't become as fuel diluted.
Adding a supercharger to a 502 Mag is an excellent idea, as long as it's done correctly. A Whipple is more upfront money than a Procharger, but there are less mods to do. If going with a Procharger, you will need to throw away their fuel system and replace it, as well as programming the ecm. Everything you need is included in a Whipple kit, including a pre programmed ecm. That's why it's more upfront money. You don't see that many used Whipple kits for sale, because most everyone loves them and doesn't want to get rid of them. Used Prochargers are not that hard to find. You can pick them up for around $2500-$3000. With either supercharger, there are still a few things that should be done to the 502 Mag. You should change the exhaust valves, springs, retainers, lock and seals. You should also change the head gasket to an MLS (Cometic) and install ARP head bolts. Another really good idea is to change the non adjustable valvetrain into an adjustable one. That requires changing the rocker arms and studs to make them adjustable. That also allows you to get rid of the stamped steel rockers and go to an aluminum roller rocker.
When done properly, either can be great setups. The 502 Mag with a supercharger will make from 600-650 hp very easily. That's quite a bit more than the 525 sc. It is also somewhat limited since it's only 454 ci. The 502 Mag can easily be upgraded along the way. With either supercharger, you can step up to a set of aluminum heads and make quite a bit more power later on when you are ready for more upgrades. The little blower on the 525 sc is the limiting factor. You will need to replace it at some point to make any substantial gains. Even then, you are still dealing with limited cubic inches.
Personally, I would go with the 502 Mag and upgrade it as money allows. You can continuously upgrade it as you go. We have made well over 900 hp with one with a Procharger, using the 502 Mag intake. Now, it was 547 ci with aluminum heads, extrude honed intake, larger injectors, etc. but it started life as a 502 mag. You can do the same thing as money allows. Let me know if I can help in any way.
Eddie
10-08-2014, 07:34 PM
#6
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The 525sc was a damn good motor for its time and still is, but times have changed. These days its pretty easy to get 525 hp out of a 454 with no blower reliably. With a 502 mag, you can get 525 with a modern roller cam and reflash, maybe exhaust. As mentioned the 525sc has a pretty small blower, you can get more out of it, but not much without significant changes. Age wise a 525sc will probably need freshening. Dollar for dollar you will get better gains from the 502 if its in decent shape to begin with. The other thought is that when you start getting up around 600 you start needing bravo upgrades, A good 502 mag wiith a cam/valvetrain upgrade will mke a bravo happier than a blower within reason
10-08-2014, 09:40 PM
#7
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I forgot to ask......how much power are you looking for? Do you have a number in mind? Do you have a certainl speed that you want to hit? What type of boat are we talking about? You may be able to make your power goal by staying NA with the 502 as Phragle mentioned.
Eddie
Eddie
10-08-2014, 10:07 PM
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Thanks everyone i really appreciate the info really helpful!
See right now i have a 23ft ultra1 with a stock carburated 330 bravo one drive runs 67-68mph not Gps but with this next upgrade i would really like to run in the 80's and want it to be reliable so Eddie i think will take your advice and get a 502mag and start from there! Thanks again!
See right now i have a 23ft ultra1 with a stock carburated 330 bravo one drive runs 67-68mph not Gps but with this next upgrade i would really like to run in the 80's and want it to be reliable so Eddie i think will take your advice and get a 502mag and start from there! Thanks again!
10-08-2014, 10:25 PM
#10
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If you are running 67-68 mph with 330 hp now, then 500 hp will get you to 80 mph. You need to figure somewhere around 13-15 hp per mph increase. That only works to a point though.
If you start with a 502 mag, then a few well placed mods will get you to 525 hp very easily. You will need to bump the compression, freshen up the heads to handle the larger camshaft that you will need, change the exhaust,etc. You may want to do a small amount of cleanup work to the heads while they are off. You can just clean up the bowls a little and clean up the chambers where the seats were cut. You can surface the heads and go to a thinner Cometic head gasket to bump the compression without going into the bottom end. If the bottom end needs to be done, then you can surface the block some since the piston is about .020 in the hole. Just by surfacing the heads and using a thinner gasket, you should be able to get close to 9:1. That along with the head work and cam change should get you to 500 hp. Don't forget that the ecm will need programming.
Eddie
edit: Just saw that it's NOT a GPS speedo. I saw GPS but didn't read carefully enough. That sounded pretty fast for that little bit of power but I'm not familiar with that particular boat. Anyway, my speed estimates are based on your current speedo (Dream meter) lol
If you start with a 502 mag, then a few well placed mods will get you to 525 hp very easily. You will need to bump the compression, freshen up the heads to handle the larger camshaft that you will need, change the exhaust,etc. You may want to do a small amount of cleanup work to the heads while they are off. You can just clean up the bowls a little and clean up the chambers where the seats were cut. You can surface the heads and go to a thinner Cometic head gasket to bump the compression without going into the bottom end. If the bottom end needs to be done, then you can surface the block some since the piston is about .020 in the hole. Just by surfacing the heads and using a thinner gasket, you should be able to get close to 9:1. That along with the head work and cam change should get you to 500 hp. Don't forget that the ecm will need programming.
Eddie
edit: Just saw that it's NOT a GPS speedo. I saw GPS but didn't read carefully enough. That sounded pretty fast for that little bit of power but I'm not familiar with that particular boat. Anyway, my speed estimates are based on your current speedo (Dream meter) lol
Last edited by Young Performance; 10-08-2014 at 10:29 PM.
