splashandburn

I am looking at buying a 358 Sonic but am not sure which engines to go with. I really like the idea of the speed that the 575's will give me but worry about maintenance, fuel economy and overall reliability. I currently own a 31 with 502 mag MPI's and these motors have been great. We do a fair number of hours per year (approx 75) and don't want to have to mess around with constant maintenance or rebuilds. Anyone out there that can help?

How about the 500 EFI's too. I've found a nuber of boats with these motors but performance wise will they be lacking??

splashandburn

Thanks for the info ....... how about the 500 EFI's vs the 575's? The 525 EFI's being so new are diffucult to find in any kind of used boat.

Turbojack

I would go the 575, but I love blowers. I think finding the boat you really like weather 500,525 or 575 would be the important thing. When you get tired all of these motors are good bases for building more HP.

splashandburn

I just checked Merc's website and they are calling for 91 octane int he 575's -- is that new??

TeamSonic42

Personal opinion from a guy who owns a big Sonic.....

I would go aftermarket... Cobra, etc. More Hp for the money. The price for the Merc power is rediculous. For the same money you can have bigger engines, with the close to if not the same reliability, depending on what you do. Build some N/A 540's with 600-650 + hp or some 572-750's.( A 38 with 900SC's went 106mph !) There are lots of builders whom have proven,reliable power plants.

Or just go with 500's and add a Vortech or similar supercharger....instant 700hp ! Very reliable and easy to maintain & use.

The only disadvantage is you dont have the Merc warranty on the aftermarket power, which would be nice. But in reality, how many people have you heard of, having to replace the power in a relatively new boat, that was taken care of ? Very few, I'm sure. If your building a new boat, Richard will put any kinda power in it you want. If I were to build a new Sonic, I would go with aftermarket power plants. I personally just cant justify the cost for the Merc power. It is proven designs, but the cost is out there for the upgrade packages.

Just my opinion........

nitro/max

Mercury 525 manual calls for 87 octane.

Von Bongo

It was origionally posted as 92 for both the 575sci and the old 525 supercharged. Sometime last year they changed that requirement. When I received my manual for the 575 it said 91 but the webpage still said 92.

When I finally received my shop manual it also said 91. The 525SC even said 92 on the flame arrestor. Come to think of it I think it said 92 somewhere on my 575.

Anyway it is now published at 91.

MIAMIBOYZ

CALL TOMMY AT CHIEFS ENGINES 954-587-3020
AND YOU CAN GET MUCH BETTER POWER FOR THE
PRICE AND RELIABILTY.

ALBERT

splashandburn

Thanks for all the input. I took a look at a bost today that has the 575 SCi's -- two year old boat with low hours and at a good price. I'm leaning towards this boat since the price is right and the power is already there. Just worry about reliability now and in the future. I'm starting to think that this is a fairly reliabe motor??