Virage Turbo/Merc 2.5 260

Randy -

I have a 1989 Virage turbo that needs help getting "over the hump". The boat is pristine with not even a scratch on the bottom.  I'm running a '94 2.5 260 with 7 1/2" of setback.

The motor has 34cc heads, three way rod slots, Hogged exhaust, Ducas reeds, bored horn, and a A-48 Digital box (set at 100%).  The motor is all nicasil and has new Shin sing?? two ring pistons from Merc. (not Weisco's).  I'm running a four hole CLE with a 30" Merc labbed Cleaver to 101 mph on GPS @ 7900 rpms.   I also have a 32" Mazco Cleaver to try.

Some fellow Virage owners with similar power / set-back are getting higher numbers. We're all running at sea level and in similar temps.

I feel the four hole CLE (stock) is what's holding me back.  I recently traded my CLE case for a SportMaster.  The case is still in the shop getting assembled so I don't have any speed numbers yet.

A friend in NY has a 225 PM W/ a SM (stock) and is getting 99.8 mph on GPS.  This is discouraging as I'm running more hp and only getting 1.2 mph more.

Was my CLE holding me back??  Is the SM going to get me into the 110 mph range?? Would it be wise to get the rpm's down a bit with the 32"?  (Holeshot isn't that important)

Sincerely,

Ron Pratt

 

Ron,

Sounds like your Virage is running pretty good already! My reply is going to be filled with my opinion so don't take anything personal if it sounds that way. Now, for what I think. I'll do this in two parts, first the stuff I've found over the years and then how we could go faster.

I used to have a Virage Turbo and have had my hands on a half dozen more. The Virage is a fairly heavy boat but it does have tunnel compression, so that helps. I've heard of these big speed numbers and have to believe they are only obtained by super high gearcases. Big props and several miles to get it there. to me that last part sucks. Why would I want a boat that takes miles to go fast? With 260 2.5's the speeds you are running is about what I found with a set-up that takes a half-mile to do. If that is the way your boat is performing now thatís good. If it takes a long time to get to 100 then we have some work to do. The CLE gearcase runs fast if it is above the bottom. Roark Summerford found at Lake X that if you fill the outside water inlets they were worth 1 mph each. If you close off the center on the sportmaster, the same 1 mph appears. On my old STV Euro I put a sportmaster on (had a CLE) and lost 2 to 3 mph. I did some creative grinding and I got them back luckily. On set-ups with the gearcase above the bottom you probably won't see much. But I could be wrong! Your set back is what I ran and I tried them all. Your motor has mods in it that like to run 8000 plus to get the maximum effect so I'd keep the R's up. The Japanese pistons you mention should be for the 225X. I'm not aware of any new 2.5 casting not made by Wieseco. If the part number ends in T6 then you have the new Malhe replacement. If T9, that is the 280 piston. Both are Wieseco. No matter as long as they work. Me and several other people have found the bored airhorn does nothing to speak of; unless you are in the 10,000 rpm plus club. Just about any airhorn mod is for naught as the drag guys found out. (Removing the front of the hood for "ram" air) It makes more noise but thatís about it. Everybody thinks that the air flow thru the airhorn is supersonic or something. It is pathetically slow.

Where am I going with this? If the sportmaster change works I would expect the rpm to go down and the speed to go up. If not much change then the Cle was ok. I'll admit I'm leaning to the first scenario. Next I think you need to get the rpm to the mid 8's to take advantage of all that motor work. Bad news is usually when you go down in pitch efficiency suffers. If we're lucky the added speed will compensate and give us our rpm back but it will most likely take a good 28 to turn 8500 and have a good performing boat overall. A 28 at 85 would put you in the low 100's and I think you punch would scare the "big mph" Virages.

Hope this helps. Feel free to contact me if you think this is making sense. Sometimes I can be kind of winded. 

 Randy

 

Please submit whatever questions you have to IHRTechTalk@yahoo.com.  All questions and answers selected will be displayed on this page as they come in.  Note: though all boaters are welcome, priority may be given to I.H.R. members.  Randy can not be held responsible for any advice given.  Though his information and expertise is second to none, he has no control over what you do with your boat.  It is up to you to boat safely and act responsibly, and his advice is only to be used as a guidance for your high performance boat/motor of which you are the one responsible for the risks involved.

Thanks,
Mark C.

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