+1 for new boat.

I doubt the repower necessary would be cost effective for that size boat.

Doesn't the stinger hit a wall at 70mph. I've read there's not a whole lot you can do to get it up to 80. Even if you did, I've also heard that it doesn't handle the speed well at all. I know its all hearsay, but I would definitely research more on the hull.

If you want to go 80, I would buy a new boat.

I know of a early 80s 39FT stinger with 900's, ext boxes, the whole ball of wax. Runs 90.

Lots of guys write off the big boats as being slow, and that without twin 1200's you cant go fast. But sometimes its not the size, weights, etc.

For example. I had a 1982 40FT Excalibur Hawk. Big old heavy wave crusher. I had a pair of 420's with trs. My buddy has a 34ft scarab III, with 420's and trs. Boats ran within 1mph of each other at top speed. Excaliburhawk40 on the site took his 40 and installed 650's or 700's, and got the boat pretty close to 80 mph i believe.

I just bought a 1983 40ft Formula SR1. Stock with 330's they were 50-52mph boats. 420's maybe 56-59mph. Mine has twin blown 454's pushing 600hp each, and boat runs a honest 72-73mph on gps.

There is nothing wrong with blowers in a boat application. If you tried to build say a 454 n/a to make 550hp, its going to be unreliable, huge cams, compression, valve train will be the weak link. Now, you can take a 454, mild cam, low compression, strap on a small blower, and make 550hp, and built properly can go for hundreds of trouble free hours. The 525SC was one of mercs best performance engines many say. Hawk 525sc's were similiar, and also great engines.

If you are on a budget, I would recommend strapping on some 177CI blowers, and take the boat to 65mph, and keep it reliable. Most complain the small blowers make lots of heat, which they do, but regardless, they were reliable, many stories here of 525SC engines living 300-400 hours without taking a valve cover off, and they maed 525-540HP. HP500 502CI/465HP carb motors couldnt claim that, good engines but they had valve spring issues around 150-250 hours.

That was the point MT. He mentioned he wanted it to run in the 80's. If you run the numbers from where he is now (55mph) with the current hp, to 80mph, he was going to require a serious boost in hp. Not to mention, eating up drives, buying new props, upgrades to transmissions and adding complete hydraulic steering. Now, if he would be satisfied with something less, he's got a great boat to start with. However, I don't think bolting on a 177 is going to net him 10mph on that 41 Stinger either.

I got our old wave crushing Fountain deep into the 80's with a pair of 675hp motors and changing to Konrads. Was it worth the money? Hell no, I should have got a newer hull! But, I like the look, the feel and the drive of the old Fountain non-steps. I also like hot rodding and building something that nobody else has, it's got more dock appeal than a new boat. So I say as long as you know this makes very poor financial sense then go for it.

Oh, fyi, another friend of mine has a 1981 38 scarab with staggard 540's making 650HP. Boat runs 75-77mph after blueprinting the hull. Boat handles great at speed.

With that being said, redcorvetteman, as much as I have dealt with the big old 80's stuff, your boat is a bastard! I love the way it looks, but it bugs me that I have never seen one like it!

The 390 Stingers were flatdeck boats(miami vice), same hull as the excalibur 40. The 375/385 stinger from 1988-1989 were copied from a european design, no windshield, molded platforms, foam cored, 6' tall cabins.

The the 415 had a deck that sloped up before the actual glass of the windshield, so with that being said, you have a very unique boat. Very Cool.

I agree, to get into the 80's, he would need some serious engines, serious trannies, and konrads at a minimum. Obviously hydraulic steering is a must.

I know of a big old boats that responded well with more hp. I know a guy who went from stock 400HP merc in a 38KV scarab that did 61mph, to 550HP engines that now runs 73-74 on gps.

Heres a good thread, 38 stinger, twin 850's, 96mph.

http://www.offshoreonly.com/forums/s...d.php?t=176506

What RPM are you turning at 55? That seems slow for 23 pitch props.

On my 1983 39 Scorpion I took out the 420's and put in 540's dyno'd at 630hp at 6000 rpm. Took the boat from 57 to 73. Still run the TRS's. When I want to cruise fast, I put on bigger prop's and the boat will cruise at 60 at 4800 rpm, but only top out at about 66-67. One of the guys on here actually had a 100mph scorpion, but put in smaller motors to keep from breaking stuff. Then he got bored. 80 top end is tough. I think you would need to have blown motors for sure. The TRS's, in good shape, should live up to around 800hp if you don't do anything stupid, and 800hp should get you 80mph. I don't think you can make 454's live at 800hp without blowers and good intercoolers.

turbines.........