HP Upgrade, Shaft & Prop Sizes

Post by **dougl33** » Mon Aug 21, 2006 7:28 am

Mike, What size shafts are you running? Since your boat's an 81, I know the 320's are not original. Regards, Doug L. 1986 33 Bertram FBC Queen Elizabeth Marblehead, MA [img]http://www.bertram33.com/photogallery/p ... sabeth.jpg[/img]

sbeer · Post by **sbeer** » Tue Aug 22, 2006 12:55 am

Doug, they are 1 3/8. Been like that since 1986 when it was converted. Don't know the shaft material, but knock on wood, havent had any problems. Mike

buzzk · Post by **buzzk** » Tue Aug 22, 2006 3:08 am

I have a 1988 FBC gas boat converted to Cummins 330 diesels. My shafts are 1.5" and I am running a three blade 23x25 Prop. slight cup. My transmissions are ZF gears, ratio 1.750:1. I have had no problems. Thanks Buzz 1988 Bertram 33 FBC Buzz Off Morehead City, NC

sbeer · Post by **sbeer** » Tue Aug 22, 2006 3:34 am

Buzz, Those are some monster props. What kind of cruise speed do you pull with them.My props are 21 x 23 with a #5 cup. Arent those 23's alittle tight to the hull? How do you like those cummins. If I ever need to repower and can't rebuild my cats, I would consider the cummins first. Mike

IRGuy · Post by **IRGuy** » Tue Aug 22, 2006 4:45 am

Interesting prop/trannie comparison: My '83 FBC has Cummins 315 HP 6B's, 1.5: 1 gears.. with 21"D X 23"P props, no cup.. Buzz's '88 FBC has Cummins 330 HP 6B's, 1.75:1 gears, and 23"D x 25"P propps with a slight cup.. Both have 1 1/5" D shafts. I suspect we would both cruise at near the same speeds.. but my engineering logic tells me if I had a choice I would go for the higher gear ratio with larger props that Buzz has. It seems to me that a larger slower turning prop would be somewhat more efficient. But, as in so many other issues.. I could be completely wrong! Frank B - IRGuy@aol.com "Phoenix" 1983 FBC

Post by **dougl33** » Tue Aug 22, 2006 5:00 am

Mike, When Bertram changed the shaft size on the gas boats back in late 1986/1987, they were all running 23 inch props because the gear ratio changed from 1.9:1 to 2.5:1. Also, its good to see that the 1.375 shafts with the 320hp Cats have given no problems in 20 years. Even if one snapped tomorrow, I'd still say it was a safe bet not to change the size. Regards, Doug L. 1986 33 Bertram FBC Queen Elizabeth Marblehead, MA [img]http://www.bertram33.com/photogallery/p ... sabeth.jpg[/img]

buzzk · Post by **buzzk** » Tue Aug 22, 2006 7:36 am

I like the Cummins. When I was looking for a boat I looked at several boats with Cats and one with Yanmars. But I really wanted the Cummins and waited until I found one that I liked with Cummins. As far as speeds go, here's the numbers 2200 21-22.5 kts 2300 22-24 kts 2400 24-25.2 kts 2500 25.1-26 kts 2600 26.8 kts 2700 27.6 kts 2800 28.8 kts 2950 29-30.2 kts The differences in the speed depends on the current. I don't have any numbers on the fuel burn numbers. Thanks Buzz Buzzk 1988 Bertram 33 FBC Buzz Off Morehead City, NC

BECCA ROSE · Post by **BECCA ROSE** » Tue Aug 22, 2006 10:41 am

23x26 props with 1 and half inch shaft, Borg 2.5 to 1 tranny. 88 FBC. Bill 33 FBC Ipswich, Ma. [img]http://www.bertram33.com/photogallery/p ... a_Rose.jpg[/img]

sbeer · Post by **sbeer** » Wed Aug 23, 2006 7:09 am

Bill, what kind of power? If Dave ever gets the spec sheet up this would all be known,lol. Mike

Post by **dougl33** » Wed Aug 23, 2006 7:46 am

Mike, Bill is running Mercs just like me. Regards, Doug L. 1986 33 Bertram FBC Queen Elizabeth Marblehead, MA [img]http://www.bertram33.com/photogallery/p ... sabeth.jpg[/img]

smanni · Post by **smanni** » Tue Oct 17, 2006 3:58 pm

I have been looking into this again- changing the HP on the 3208 cats. I spoke with a guy today that is extremely well respected as a Cat 3208 guy and he was familiar with the situation of our boats being "DETUNED". He said that it is extremely easy to re-adjust them from 270 to 300 or 320 and that mu shafts, although marginal. SHOULD be ok. So the last question is the Transmission. Can the tranny handle another 30 HP. He will do the tuning for 300.00 through the Canyon CLub in Cape May NJ. I think I might do it!

Sean B · Post by **Sean B** » Tue Oct 17, 2006 9:44 pm

I got a little different story: new (or re-worked original) injector pumps needed. If you can, get exact technical details from the guy about what he is proposing. If all he is changing is the max fuel setting on the governor, be cautious. In my engines' case I was told that the injector pumps simply will not feed more fuel to get more power, hence the required rework of those. Also been told that a lot of guys are out there offering to change that max fuel governor setting - but without the corresponding injector pump changes - it really doesn't do anything except raise your WOT no-load RPM. In my case there were also some governor spring changes required as well. If I were to change those too, but not do the bigger injector pumps, the engines would be constantly starved for fuel while under load at all RPM ranges. So be careful. The injector pump is like a little gear-driven mini-V8 engine itself, with each pump piston pumping fuel for each engine cylinder injector. They need physically bigger parts to put out more fuel. There are a lot of different 3208 setups. If he didn't research the differences between your setup (through your engine arrangement number) and the setup/arrangement numbers of a similiar 3208 block but with a 320 HP setup, I'd be leery. My CAT guy did all that and came upon the differences in the injector pumps. On the other hand, if your guy does seem to know what he is doing, I'd be happy to pay for his time to have him research my engine arrangement numbers and give me a bullet list of what he thinks needs to be done to increase to 320 HP. I want more than one concurring opinion before I start dicking around with my engines anyway. As for the tranny, you may have MG502-1 gears as I do. Gears also have a "build sheet number" (I think that's what they call it anyway) like the engines, and you can call Twin Disk with that number and get your rating. My particular gears are rated at 250 HP, as it is common to rate them 10 HP less than the engine HP rating as ordered from the boat manufacturer. Most of these TD MG502-1 gears are rated at 275-300 HP, and it seems that the difference between those and mine are the serial number plate on them. I talked with and got sort of cryptic answers from a Twin Disk factory guy who seemed very knowledgeable and experienced. I got the impression that he had been there forever. At first he didn't want to say anything about going over rated HP, so I kept bugging him, a lot. He eventually told me they were all built the same despite whatever HP the plate said, although 320 HP certainly exceeds the max factory rating, but also there is a safety factor. He said he personally thought it would be okay, but he can't tell me the gear safety factor as that is secret info, and it depends on how my gears were taken care of, and also that he can't officially promise anything about going over published ratings except it is officially not recommended (read all that as: "afraid of lawyers"). But basically he said the 502-1 was a "tough old gear" and that he had never seen one fail except through abuse, so with increased HP don't run all day at WOT and don't shift above idle and they should be fine. I was surprised he felt the need to tell anybody those things, but there are all types of boaters out there I guess. Let me know about what your CAT guy wants to do - more details please! Sean Burlingham "Island Time" 1987 Bertram 33 SF Melbourne, FL SBurlingham@cfl.rr.com [img]http://www.bertram33.com/photogallery/p ... d_Time.jpg[/img]

smanni · Post by **smanni** » Wed Oct 18, 2006 2:54 am

Sean - I will let you know what happens. This guy is the CAT service manager at the Canyon Club and I have heard from 10 different people over the years that he is the best around. He said it will take 2 hours and will be no problem. I will, just to be cautious, ask him to double check the engine configuration. He is advancing the max fuel setting on the governor - but that isn't where the HP is coming from. He said the HP comes from something else that he is advancing (but I forget exactly what). As far as the injector pump - he said they are all the same from 260-320 and will not need to be changed - but, I'll have him run the numbers to be safe! I will update after I speak with him again later today! I hope this works.

mikecobos · Post by **mikecobos** » Tue Mar 13, 2007 2:29 am

quote:Originally posted by Sean Burlingham I have a 33B SF that has 260 HP 3208T Cats, 1.375" Aquamet 22 shafts, Model MG502-1 twin-disk 1.54:1 trannys, and 3-blade 20x22 props. All this is stock on my 1987 model. I've found that to cruise at optimum 20-21 knots I have to keep the motors at ~2600 RPM, which is a little higher than they should run at. I've researched and learned than I can boost the engine output to 320 HP by changing some things about the injection pump and governor. My question is to those who have this boat and 320 HP engines: what size shaft and prop do you have? I know that my shafts are marginal and I intend to upgrade in the future, but want to do engine upgrade now and keep existing shafts for the time being. If anybody has stock Bertram 33 with 320 HP I'd be really appreciative to know what size shaft, prop and tranny ratio the boat came with. Thanks!

mikecobos · Post by **mikecobos** » Tue Mar 13, 2007 2:31 am

i have 87 s.f.with 370 cummins ans 1 1/2 shafts. i broke 1 just behind strut last year. i thinking i need 1 3/4