rhsj2006

Looking for some expertise here...I've been trying to find some ways to economically add HP (economical HP - is that an oxy-moron?) to my Formula 292. An inexpensive bolt-on route may be installing 1.6 ratio rocker arms in the heads (more valve lift) and Stainless Marine or other more free flowing exhaust manifolds.

Twin engines, so supercharging her would probably run me $25k including the SC, exhaust, gear change in the drive, labor, etc.

Am I being foolish, tinkering with these 6.2s? Would really like a little quicker plane, a few more MPH on the top end...Besides the mods I mentioned, other ways to get some extra juice out of the 377's?

spilman

I am trying to get some hp out of twin sb's also. 2 years ago I added the Stainless Marine exhaust systems & got a few more horses...maybe 15 each engine. I noticed an increase of 150 rpm's and then got new props and had them labbed. All-in-all, I saw 2-3mph and spent $6,500...but the props were nec. since the old ones were cracked(labbed too thin by previous owner).
I have to look @ my port engine; a valvetrain or head gasket problem so I am going to start going thru both motors soon. I hope to get them back to equal/tight compression and then add the Prochargers. The kits for our sb's are $4,500, I believe and I would install them myself. I'm looking to get into the low to mid 80's.....what speed are you seeing w/your current set-up in the Formula?

rhsj2006

On my stock setup I'm getting 70-72, depending on load and water conditions. Would love to see high 70's or even 80, but as we all know, speed costs $$...

If I'm going to supercharge I think I'd go with Whipple - Seems to be a cleaner package and provides more of the bottom end torque. Speaking with Whipple, those are about $7k per side, + you need oil coolers, so with exhaust and labor I estimated $25k. Would do the labor myself but store the boat an hour from home.

rvtransport

I have a 06 292 with same power. Mine ran 70 perfect conditions 68 most days with a load. I added revalution marine exhaust and 1.6 roller rockers and changed props from 28 labs to 30labs. The boat gained 2 mph and is a little better out of the hole. I have not had a chance to run the boat light with no people low on fuel yet. It my run 73 to 74 in those conditions. Best so far 72 at 5100rpm 3/4 fuel 2 passengers.

Whipple Charged

25k? Come on man, your killing me. Theres no better power vs. speed than the supercharger, especially with the EFI motors since were the only ones that do the computer. Keep your factory exhaust, keep your gear ratio unless you are running bravo 3 with 32 pitch props. Otherwise, SC, props, oil cooler and labor, then your ready for a big change in boating. You'll make 475hp with stock exhaust, which should be good for approx. 15mph in your v-bottom.

SC Kits $6799.99 each
Oil cooler $139.99 each
Bravo one props $449.99 each
Labor each $2000 each
= $9389.97 each.

There will be some small other charges, but you also can get a better deal on parts if you search, as this is MSRP. My labor quote maybe on the high side as well.

If you try different ratio rockers, which will do very little and exhaust, at best, you would get 4mph, but more than likely you'll be closer to 2mph. Depending on where your propped or geared, you may not have room to go faster if your close to rpm limit, therefore you may need more prop/gear, but won't have enough torque to get decent acceleration. Could lab the props, but there you go again.

Thanks,
Dustin

Whipple Charged

Try contacting Mark @ Semper Speed and Marine (559.436.1888), he's in Madera, just outside of Fresno. About 2.5 hours from you. He's done a bunch of our SC's, and since its local to me, if there are ever issues, I'm always going by there and can help out.

mama tryed

I'd like to hear a little more about that, all I can spin is labbed 24 Three blades with my Sun.

clpbs

I agree lab 30 is a big wheel for those speeds. I run lab 30's on my 35 ex with 525's running 86.

4mulafastech

Sounds easy enough Dustin, but do you have any examples demonstrating the long term reliabilty of a swap like this on stock 6.2's? I have the same boat as rhsj2006 (292 Fastech) and they are pretty heavy boats.

Couple questions. What boost and what octane is required in your example to get 15 mph? These engines only hold 4.5 qrts of oil. Is a $140 cooler enough, or should you try an increase the capacity? Does the SC kit come with larger fuel injectors or are the small stock ones enough with a recal? The stock exhaust on these 6.2's aren't much better than the old style logs (they aren't as nice as stock 496 manifolds). Wouldn't a free flowing exhaust offer a pretty good bang for the buck on a blown engine and also reduce combustion temps?

Don't get me wrong, I really would like to believe 15 mph can be this cheap and easy, but my concern is long term reliability. I want to hear from people that made this swap and have some run time!

4mulafastech

Anyone out there Whipple their 6.2 MPI's? If so, how was the conversion and are you happy with the performance and reliability?

Thanks,
Dave