Bertram33 User Forum

Gents 250 hrs each engine 0.7 mi/gal cruise @4250 RPM/23-25kt WOT 0.5 mi/gal @5650 RPM/32-34kt Garmin speed, Maretron Fuel burn Props 21 x 25 Nibral Med Cup. JUMPS on plane Only problem so far was both low pressure fuel pumps replace on warr.

Replaced 454's in a 33SF with MarinePower 6.2 LS3's (425HP)cruise at 25kt WOT is 32-33kt. Cruise 0.7gpmile WOT-0.5 gpm. Was ablt to keep orig running gear. Eng/Trans combo ~$20K ea (need new trannys as the LS3 not available in counter ROT)

not sure how to post pics, but I have them if you want

Tom, Sorry for the VERY late response but here is what I know for what it's worth. Only had to move between 6-10 inches. As I replaced the B.W 72 trannys with the ZF All worked out well as the ZF's are shorter by almost that amount. A bigger problem was that I had to raise the engines almost 2-3 inc...

quote:Originally posted by h2ojst Hi Tom, I'm the one with the down angle trany's. I moved the engines back almost a full foot & yes, I needed new shafts. The plus side of this is you get lots more room in the front of the engines to work & the boat tends to sit better in the water. (SF's ar...

DougL33: Correct, the available added RPM's is 200-400! Will do burn tests through the cruise range (~3000-4500 RPM =~18-28 knots) when I have enough time and weather conditions to go thru a range of sea conditions. The numbers reported earlier are indeed in nmpg...the main 12" display is all i...

Still working on props as there is another 2000-4000 RPM available without stressing the engines per Marine Power!

Cruise at 4000RPM, 33 mph, 0.7 mpg WOT 5050RPM, 38 MPH, 0.45 MPG Both number fully loaded...water, fuel, ice (no fish though, 30 gal bait tank, 6 good size POB plus all the crap that accumulates in storage!

gents, Maybe I'm lucky, but my 33sf has an aluminum tank! Fuel burn TBD next two weeks with full instrumentation.

Gentlemen, Thanks for all the info. As far as definitive info MarinePower (MP) in writing advised me to prop out the engines at 5200+/- 100 RPM. MP's spec for the engine (GM's spec doesn't count as it is fully marinized using MP's MEFI 6B program for the ECM). The stbd tach is within 50-100 rpm and ...

Thanks for the suggestion. I do need however to correct a typo...the current prop is the Nibral but it is a 21 x 25p speed and RPM are correct. Not sure how to move the post over so I will try contacting by email if possible.

FINALLY!!!! After 7 months and ~75K it's back in the water. Propping has been brutal(ly expensive). Been thru 3 sets so far and even Mich Wheel's recommendation (20 x 20 Nibral) was way off. The results are as follows" Fully loaded (23,600#) 23 x 25p Bronze 4500 rpm/33 mph 20 x 20 Bronze 5400 r...

The original sensors are NOT thermistors (change resistance with temp) they ARE what is know as snap switches they are normally OPEN when cool and "snap" closed at 190F. They may or may not reset depending on any fire damage. A low buzzing is indicative of less than 12V reaching the bell. Al

The mfg specs for WOT (max) are 5600 rpm, but that is derived from the GM specs (which is max rpm of 6600!) for the LS3. Since they are not avail in reverse rotation, we needed to change from Velvet Drive to ZF trannys, which will run one fwd and one rev. I think 5600 is too high. Based on additiona...

Hi I'm new to the forum Have had my '88 33SF for 2 years and are replacing the original 454 (340HP) with the 420 HP 6.2L Injected V8 (Gas). Torque is rated at 4600RPM and HP is rated at 5600RPM. Any suggestions for WOT target RPM for propping. Currently have 23 x 25 and 23 x 26 props available. Al W...