forester

Zuckerman, you've been through all what I'm just starting so I will ask the pro. Took the new boat out yesterday...42 sonic w/ 575's. With the stock 4" pulley's it was pulling 7 lbs at 5100! I thought stock was 4 lbs? I was going to remap and go with a smaller pulley but I can't if it is already there. Does cool air make that much difference? Thanks for the help.

Steve Zuckerman

Bob,
We are going to cryo treat my gears. So I may be down for a little while (a week or so). Thank you for the kind offer.
I will give you a shout when I'm back together. I still have your # on my cell. How is your motor coming? Sounds like you're getting close!
Regards,
Steve

Steve Zuckerman

Forester,
Cool air does help the boost level on the 575, but not 3 PSI, in my experience. Maybe 1 PSI.
Were both engines reading the same boost level? You can cross reference that way.
Here's my experience with the Weiand/Merc 256 on this motor.
stock 4" pulley at stock rev levels (5100/5200) = 4 PSI
3.5" pulley with revised ECU (5600 limited) = 6 PSI
3.5" pulley with Whipple intercooler = 4.5 PSI
3.25" pulley with " " = 5.5 PSI
3.0" pulley " " " = 6 PSI
3.0" pulley " " " @ 6000 RPM = 8PSI
Reprogramming the ECU to 5600 limit and an intercooler really helps these motors out. The low compression ratio (7.5 to 1) responds well to increased boost levels. Spinning the W256 to these boost levels unfortunately generates more boost heat, which makes the intercooler a nice addition. You should be able to pull a very reliable 700+HP out of your motors with these "bolt ons". Beyond that, gotta go to internal surgery !
Good luck. Keep us posted.
Regards,
Steve

bobl

I just haven't had time to work on it. I've got a couple of builds in front of it that I've got to finish first. The long block is assembled. Just need to bolt everything on and get it on the dyno.

forester

Steve, forgot to ask...Buddy has a new heat closed bow, went in the mold Thursday, with 525efi. We are @ 1300 ft with 80* air temps. What I'm I gonna be up against? And yes, both gauges were reading the same boost on the sonic. Thanks.

Steve Zuckerman

forester,
#1, I would advise your friend to have Nordic install his drive @ 18 1/4"s X-dimension. For some reason, they seem married to a generally too high 19 1/4"s. That's why so many of us have to use 1" spacers on our drives.
I'm not familiar with your altitude and the issues it causes. These boats run almost 80 at sea level and good conditions, to 75ish with 525s under hot humid summer conditions and lower altitudes. I don't think they've made any bottom changes with the new boats.
Regards,
Steve

Nordicflame

iTrader: (4)

Steve,
Do you have a Diacom?
I'd be interested in your intake air temps with that blower at 6000 rpm.
Thanks,
Dave

Steve Zuckerman

Hi Dave,
Unfortunately not, but I think I know where you are going with this train of thought. No doubt, I was spinning the hell out of it before @ 5500 with a 3" pulley. @ 6000 it's crazy fast, like 57% OD.
We are going to test a 3.5" pulley as soon as the drive is back together. I think the slower rotor speed will reduce my boost, but also reduce intake temps, hopefully offsetting each other.
Eric thinks I may lose some acelleration, but the top end #s will be similar, if not the same. And that hard working W256 may live longer too .........
What do you think?
I have a friend here who's putting Blower Shop 871s on his 575s/42' Fountain. We have before #s. Should be an interesting comparison vs the W256s. Wish I had the vertical room to do the same. I have another friend with the same space issue (29' Fountain/575) as I do who's replacing his W256 with a BS 250 low profile billet blower. Should also be an interesting comparison.
Regards,
Steve

bobl

Steve, just some food for thought. You really have no idea where your peak HP occurs(from dyno run). Something kept the dyno from reading torque above 570. My guess is something mechanical, like the torque arm hitting something that limited it's movement. So, all we know is the torque stayed above 570 up to 6500 RPM. The boost should stay fairly constant with a roots type SC. The fact that it started climbing at the upper RPM may be an indication something is not quite right. Your power may have started falling off as the boost was climbing.

Steve Zuckerman

Bob,
Thanks for your analysis. Something was definitely amiss with our dyno tests. All we can do at this point is test pulleys/boost, and A/F ratios/timing/etc and props. I think we're pretty close based on the way the boat is running. I figured boost normally climbed with RPM?
Hopefully we'll arrive at the right combination. How much horsepower can your propshaft dyno safely test?
Regards,
Steve