Supercharging question
 

Why do the likes of mercury use supercharging on their 600 and 700 hp engines. It would seem that there are plenty of engine builders making this sort of hp from na motors with ease and reliability. I would have thought the superchargers would just add to initial cost of production and lessen time between maintenance?
Have been doing plenty of research for my next build and had initially figured I would build na 650-750 hp for reliability but then every time I cross to the mercury racing website I doubt myself seeing they have always stuck a blower on anything over 600?
I guess the key for me is reliability/dollar. Do they even go together..... Probably not!

kurt,i think merc uses supercharger on 575&600hp engine is because to make power with na engine,it requires good cylinder heads,large cubic inch setup,and higher compression ratio,all these things cost money,after all,from a business standpoint,its all about making money.at one time merc had a 525sc,it used a 7.5 compression ratio,single 1050 dominator carb,mild hyd flat tappet cam,and gm rectangle iorn heads,454 cu in and was a good engine in its stock form,now the supercharger is gone,replaced with turbocharger.

By SCing you can run smaller cams and increase valve train reliabilty.

To make 700hp NA, you need big cubes, and a big cam or at least more rpm. All of these shorten valve train life.

So what is the maintenance schedule for a 600 sci (mercury) vs a 700na built by a reputable builder (best internals etc). A merc 600 isn't exactly cheap so I assume sc's aren't cheap? I figure cubes are a way cheaper alternative also. Tell me I'm wrong, just want to go down the right path. What would you guys do if you where after that hp? Na vs sc?

Don't remember the exact schedule, it was up in another thread in the fall and Mercs explanation was not very precise to say the least. I think it's about 200hrs for top end and 3-400 on bottom. I'll bet Eddie Young could build you a cheaper, better and more powerful motor for the same money than any of the Merc sc offerings are. If you want a "big" brand motor, look into the Ilmor 650 or 725. Better service, lighter motor, better rebuild times and cheaper, not to mention they sound A LOT cooler:) Better milage too and closed cooling:) The 650 has VVT, so it will have no problems with low end torque.

Just my o2.

this debate has been going on since they invented the chargers...no easy answer...i prefer sc,as you can take a mild engine and make a lot of (reliable?) power out of it,all the while keeping the non-stressed components...the 525sc is a good example...very reliable,even without an i/cooler.....jmo
jack

+blower whine gives me a boner!!

Also with the blower you can get better economy out of it as its not making much boost most of time making for better economy and when you want the extra H/P it's there...thats why you are seeing more and more smaller engines with blowers/turbos in cars/trucks now days...

So many people think superchargers=unreliable. This is probably mainly coming from info that friends of friends have passed on over the years, based on some guys Dad who installed a supercharger on his car in 1984 and couldnt keep the engine together because of lack of information.

Nowadays, the product is there, the information is there, why not use it. Theres a reason all the big name marine builders are building supercharged marine engines, with full warrantys and good results.

I have had little 460CI supercharged marine engines for several years now. They make just as much power if not more than some of my buddies N/A 540's, and lasted as long if not longer, and run just as good if not better around the docks and what not.

I thought super chargeing used alot more fuel is that not the case?

Well, yes and no. Sure supercharged engines are normally setup to run a bit richer than a N/A engine. But, at the end of the day it takes X amount of fuel to make X amount of HP. A750HP n/a engine should be close to a 750HP supercharged engine, fuel consumption wise. Of course modern day EFI systems help alot with that.

Alot of people think just because a blower engine might have a pair of 800 CFM carbs on it, that it just dumps gas in the engine that the engine doesnt need. Really not true. If that were the case the engines would have a crankcase full of gas and pour smoke out the exhaust.

A dyno can tell you alot of what the engine will consume as far as fuel goes. Mercurys supercharged engines were known to be gas guzzlers, but they were also set up to be very rich so they don't burn up under warranty.