How much HP will MercTrans take?
 

Any one have any experience with loading the old MercTrans with some power? The trans are 78's with very low hours and and had 330's mounted to them. I am running out of time would chance it if there's a remote possibility they'll hold up due to the time of switching all the plumbing, oil coolers, lines, wiring, cables,moving the engines forward, etc. I have BW c72's ready to go but...
Thanks for the advice in advance from those who have tried this. I am looking at appx. 615 HP however plan to use the boat very little this season and would just like to get on the water. Even if I have to leave the throttle lube at the dock. lol... Also will ease on plane and take precaution on wave hopping. If it's NO WAY option I won't do it and take the winter and move forward as planned. Just really wanted to have a little time on the water this summer.

FYI This is for a 32 v bottom light layup.

Years ago I ran 550 to 600 horse twins in a 31 foot boat with merc trannies. This is what I learned

1. Keep the props in the lake.

2. Take it easy out of the hole.

3. If you blow a drive while running you will take out the tranny with it 99% of the time.

You should be able to enjoy your boat for a while.

Kris Vogt

go here

http://www.offshoreonly.com/forums/g...-trans-ii.html

I know a guy with 420hps with BM250 blowers 38TG, blows two a season every year.

If you plan on keeping the boat, better to find some 71C's BW. They fit in the same location as the merc trans and the engines don't need to be moved. You can have 71C's built and speced as Huber 925's. That's what I had built for the Cigarette Mistress that I used to own. They were mated to TRS and then Konrad Drives. good luck!

Thanks guys,
Just can't believe I let this slip by without giving it a thought over the past couple of years while working on the project. Kind of sucks as I just rebuilt two c72's and bought a couple more for spares that are being rebuilt. Hmmm. I guess I could move the #4 - c72's and go the 71 route if I can find a couple quickly. Do you still use the same bell housings and tail stocks or don't those require tailstocks? Hopefully at the very least I am able to use the housings as I bought all new 8 and 13 plate coolers and covers.... ?????


I should have researched this a bit before hand. All the years boating I didn't mess with the trs stuff much. When I was purchasing the BW's I was told (no problem or big deal) on the swapping out of such, just need a couple of bell housings.
Oh well. Just want to move forward and enjoy the summer. My 12' runabout with a 5hp just isn't cuttin it. LOL..

Thanks again for the help.

71's will not fit in place of the merc trans. Here are pics of the two. 72c is a 10-18 and a 71 is a 10-17.
Here's the 71
http://cgi.ebay.com/ebaymotors/Mercr...item2550cf4545
Here's the 72
http://cgi.ebay.com/ebaymotors/Mercr...item2562545bba
They are the same size. Remember you are also going to need B-W input shafts for your drives. I would go with the Merc Trans for now and make the swap this winter. Hell it's almost 4th of July. I believe they do use the same bellhousings and tailstocks. Stick with the 72's you got. They are suppose to be better that the 71's. Sounds like you got enough transmissions sitting around now.
Just don't be driving it like in your avitar!

Picklenjim is close, they are almost the same size, about an inch difference. Niether will fit in place of the Merctrans without moving the engine.

Sounds like a plan. It's just going to be difficult to stay out of the pins. I have the BW drive plates however any ideas of where to find the input shafts. I may just proceed as planned rather than wasting time and doing something half ass.

Doesn't look like the rear bulkhead is going to be an issue. My main concern is the moving the weight forward and just locating the proper shafts. I would think there should be some of those around yet.

Thanks again,
John

You can still get them new. Part #57749A 1
It's part 35 in the diagram. $257.42
http://www.perfprotech.com/store/ass....aspx#assembly

Thanks for the help. I'm pretty certain this is the way I am going to go. I've spent a lot of money and time on this project between the deck mods, new paint, interior, engines, rigging, accs. and so on. I really hate to take short cuts and have that on my mind that things aren't the way they should be and also finding the nearest port limping in on one engine. If anyone knows of or has any of those shafts I need and are willing to part with them please let me know. I have been spending more than I am earning lately. Just another expense I wasn't planning on.

Thanks again for your help and understanding.

John