docmanrich37

I was running 1.50 max machine drives and bought 1.30 bmax drives and lost 10 mph.was running 32 4blade stock mercs with the 1.50.Tried 26 4 blades stock mercs with the 1.30 but tried 28 4 blade stock mercs and gave me better cruz speed and ran 2 mph than the 26's.26's where turning 5400 and the 28's are turning 5100 rpms.The 1.50 i was turning 5800 with 32 blades at 100 mph.The bravo shop hasn't been any help to me in finding the solution to the lost of mph.I knew i would lose 2-4 mph with the 1.30's but 10 mph is way 2 much.The bmax lower has a 8" skeg verses the 6" skeg on the bravo lower but thats not 6-8 mph lost.I think i'm the only one having this much mph lost.

t500hps

Keep it up and you'll have to do the Hampton Poker run next year with the Cruiser group!!!!

Back4More

Try and prop it at the rpm you where running @ before the upgrade.
Also, did you re-check you drive alignment? If your spinning out... have your drives at about 1/8" toe out.

zt260

I've never ran a 1.5 XR long enough to compare to my 1.3 bmax. The last time I tried the XR blew before I could get close to top speed. As a general rule at speeds over 80mph a 1.5 will be 5mph faster than a 1.3, if you don't run out of pitch.

If you add in the 2-3 mph the bmax consumes and the HP loss at 400rpm down I can see a 10mph loss.

Are you at 90mph with the bmax at 5400rpm? If so your slip is only 8%, I'd try a shorty. That's what I run.

docmanrich37

If i try to prop it at the same rpms as my 1.50 i'll need a 24 pitch set of props.That won't work.26's only got me 400 rpms and no more speed.best props so far are 28 stock running about the same speed as the 26's with less rpms.
It looks like to me from talking to everyone that has these drives that i;m the only one having this problem.



2 slightly used bmaxs for sale with alittle over 20 hrs on them.$20,000 plus shipping.will not split them up.Better yet $UMTHING$ GOTTA GIVE IS FOR SALE in the swap shop.

Back4More

I run 26's

BillR

You're not gonna give up boating are ya?

What about putting your old drives back on? Bravo shop not willing to help you any more???

Back4More

That sure is a nice boat.
I would still try 24's and see what happens.
Hard to beleive XR's won't live on there....BTW, How much boost?

Strip Poker 388

iTrader: (6)

Rich
I was running the BMaxs with the 24pith 4blabd brave 1.30 gear with my stock 500efi truning the motor 5400 max which was about 82-84 MPH on my 388 Hustler..At 760 hp with the whipples I bought stock 28's and turned them 6100 on a lite load and cooler temps.in full load heat of the summer it would turn 5800-5900. Now I am at 848 HP and turning stock 30's 56-5800 at 98degrees and 91 degrees lake water temp at 57-5800 GPS was 99.8. on flat water!! Last year the best at 6100 I saw 100.4 GPS. The worst it will run is 97.5 flat river water no matter what.


Rich I can see maybe 1-3MPH loss but not anymore than that...there has to be something else.Did you ever get it to quit fouling plugs.You said you were getting a exhaust oxgyen meter from Dustin ,What did ya find out with it running so rich???? Maybe Tyler is way off on the map ????

Keep tunning it and playing with youll find out whats wrong.


Rob

docmanrich37

The ecu has been fixed.Dustin did good on it for me.I'm going to try 1.50 bravos maybe next week like what i had before just to see if anything has changed but i know it hasn't.It is the bmaxs robbing my mph but don't know why and don't think the bravo shop knows either.

BillR yes i'm thinking of going to a cruiser,just tired of all the b.s.
Back4 More i was told 24's wouldn't help to small.My boost should read 7-8 but only reading 5-6 lbs.I havn't broke any xr's with the whipples but wanted the so called better drives so i wouldn't brake drives.

I tried a set of 26's and it didn't do anything except 400 rpms more and lost 6 mph at cruise.Talked to Throttle up and she said with the 26's i was at 9% slip and 12 with the 28's.

Strip the boats been running great other than when i first start it up after setting for 4-5 days it will shut off if i try to take off with in the first 5 minutes of it idling.I havn't tried a o2 sencor reading on the new ecus cause its been running great since last month.At this point i just want to finish out the season unless someone brings me a check for the whole package.Boat,truck,golf cart and even the 42" r/c boat.I spent alot of $$ togo a 100 mph and got it until i installed the drives so if i could get some answers to why i lost 10 mph from the drive dealer that might help.Thanks Rich