outlawinil

I have an Baja outlaw with twin 7.4L's. Wanting more speed. Everybody says no blowers on these motors but companies are making them anyway. Anybody got any experience? Leaning toward dropping in 502's, any suggestion on where to buy? Motors have less than 40 hours on them and still under warranty, I hate the thought of practially giving them away.

KCHOTBOAT

Best bag for the buck blowers. I ran a 7.4 carb motor with a ProCharger and 9 pound pulley for three summers hard before I blew the motor. Once you add the a blower your motors will not be under warranty. Buy whipple or procharger run low boost and should last for sometime. You can always add the blowers to the 502s when you blow the the 7.4s.

Brad Perry

There are several here on the board that have made reliable power with those motors. Some good heads, cam change and exhaust will work wonders. Just don't spin them past 5200 or so. You can always take those components on to the next engines if you change later.

Audiofn

Are these 300-330hp motors, or Mag motors? What you need to do is give Dustin Whipple a call. Just remember this is the time of year all those guys are gearing up for boat shows so you may have to be a little patient. I know that he has said on the board that they have had very good luck running low boost through 330hp motors, you just have to keep the boost and the RPMs lower then what you would with a MAG motor.

kook

Repower.

Your profile says you run a 2000 boat, so we must be talking about the 7.4 MPI here? That is what I have in my boat, and I did some research on the subject - no expert, but I thought I'd share my though process.

I wanted at least 500hp out of the motor. Putting a Whipple on it would have gotten me close, but I'd be running the snot out of the thing to get that hp.... There's nothing hi-po about the standard 7.4MPI motor - so many differences between this motor and the Mag motor - crank, heads, rods, pistons, etc, etc, etc... The 7.4MPI belongs in a truck, or left stock if in a boat, IMHO.

I decided to go with a large CID n/a motor - (much) more power than I could have gotten out of a huff'd 7.4MPI, and more reliable for the type of running I plan on doing with the boat.

It will be tough getting 500hp long block for the same INITIAL cost as adding a blower to your existing motors, but look at it this way: the LONG TERM cost will be cheaper going with the bigger n/a hi-po motors - grenade one of your blown 7.4's, and what 'ya gonna do? Buy another 7.4 long block? bam! Your total cost is now about the same as it were if you had bought 2 hi-po n/a motors. Blow the other motor? BAM! Your total cost is now more than it would have been if you went for n/a hi-po motors. Not to mention the price for peace of mind (or lack of it, if running blowers on the 7.4MPI)

You'll have to go carb'd motors to keep costs reasonable, unless you can find a good deal on a PAIR of used 502 MPI mags - still then, you are only talking 415 prop hp.

It gets interesting when you think about what you can do with your 7.4's if you replace them with hi-po carb'd motors. You could sell both this summer, get at least $7k for the pair... or keep them when you re-sell the boat, and sell the hi-po motors seperately at that time.... If you thought that re-sale would be hurt if the boat was rigg'd with non-Merc motors, you could intially sell your 7.4's, then when you were ready to sell the boat, find some good used 7.4 Mags, drop them in, and sell the hi-po motors seperate from the boat, or use them in your next boat, if you ever think you will get another boat.

You should be able to get a 550hp 502 motor, including carb and intake, for around $7000 or so, I would think. Talk to Bruce, and see what he can put together for you.

Play with the numbers, and see what you come up with. There's more to the equation than the initial cost.

[ 01-12-2002: Message edited by: kook ]

turbo2256

I have two boats with the 7.4 one is carb the other is EFI. the EFI is stock for now but the point is I have found its cheeper to upgrade the 7.4 intrenals than it is to purchase the bigger motors. The oval port after market heads produce more torque and ported more flow than the square ports. The carb motor is currently a 7.4 stock bottom end with mildly ported Edelbrock oval ports 750 Holley and Edelbrock dual plane needs some better manifolds for maybe another 60 to 80hp but in curent form I went from a 23 to a 26 pitch prop. Heads with inconel exhaust valves for about 2000 forged crank rods and pistons for about another 2000 non roller cam and lifters under 200. If your runing saltwater add enclosed cooling you will out perform a 502 andhave better gutts sell off old pars from 7.4.Get the idea. About 550 hp or better can be had.