power in a 38 stepped fever
 

just redid my motors and dynoed them . They made 642hp at 5300 and 720ftlbs. I am a little unhappy with the hp # what can I expect for speeds. motors are 588 talldecks. I was hoping to get to 90mph but Idk. the torque is all there and then some but will that lower hp do the job? boat is a 98 stepped fever with -2 shorties side by side. last year with the 540 talldecks spun 30p5xs to about 5000 and ran 84gps what do u guys with think??

Need more info. Show or post dyno #'s. Need to see #'s thru all rpms tested.

What cam, cid, heads, compression ?

I think you should be close, what rpm was your peak torque

What did the 540s make? You'll probably be in the upper 80s. 90 will be a stretch with only 640 a side.

My 38 Fever took 720hp a side to run 92mph, Re degree the cams ,turn the RPM'S UP & let her eat . The boat could run low 90's with 588 inch motors easy!

I would guess the 540s with a reasonable build would make 620-650 hp.

Peak torque was at 4500 I will get the sheets today

Racn fever how much torque did u have with that 725 hp I guess I tryn to find out if I need to go back in and change cams intakes and carbs to dominators. U think my big torque # will carry this boat

Need cam specs , intake & carb info, cyl head info, & header type . Looking at your dyno # you may not have enough cam to make HP in the higher RPMs, Somethime Engine Builders are not able to run the big cams to make power in large CID motors due to inadequate exhaust headers.Best to keep CID around 540 unless you have $$$ for BIG TUBE HEADERS.

TQ peak at 4500 and HP peak at 5300 rpm ?

Somethings off big time. Peak hp is typically 1200-1400 rpm higher than peak tq.

Still haven't answered parts used. Will be helpful to see if it;s a problem there or in tuning/rigging.

Got dyno sheets so we can see fuel flow #'s, intake cfm, A/F ratio's, etc,etc ?

cam 110 cent line 246 duration int and exh 630 lift int and exh. bb2 extra heads cncd chambers 9.35-1 comp, 588 inch tall deck merlin intakes 4150 100cfm carbs peak torque at 4400 and peak hp at 5300rpm. air fuel at 12.8-1 don't have the sheets motor still there awaiting my changes as soon as I decide what they are going to be. dyno guy said the cam is way to small for the motor. said it flatlines at 5300 im thinking I need cam intale and a big dominator

Was the air fuel ratio calculated or measured in the exhaust?

in exhaust with a sensor

Although your cam is not ideal, I have not seen a camshaft be responsible for a 800-900rpm spread between Pk Tq and Peak Hp.

Induction / exhaust / fuel supply or metering / ignition / valvetrain ...yup, seen those cause it.

Who's 1000cfm carb ?

What ignition ?

Your fuel pump or dyno's - and what is it ?

What's your minmum fuel supply/feed orifice size ?

What's the actual valvespring rate as installed - not stated.

You need a good Marine cam 250- 260 degrees@50 on a 114 LS, I will call you today.

dynos fuel pump dui ignitions pro system carb re done 2 weeks ago by aed -8 fuel line spring are 140 at 1.94 installed height 425 at 1.250

The BB-2Xtra come with 2.300 intake valves. The 140/425 springs may be a little on the light side for controlling them #1. #2, many shops do not test the springs on purchased 'assembled heads' and therefore improperly set up springs can be missed. IE: the springs may have even less psi than stated.

My IMHO is that 140/425 springs are even on the 'light side' for 2.25 intake valves reving to mid to upper 5k's.

Not saying this is your issue, but saying that it is very suspect as 1 issue. Not comfortable area for me and probably others. 170-180 seat is more the norm for performance HR's now-a-days.450-480+lbs open. For instance Many HP500 (222 at .050" HR) /500EFI's (230 at .050"HR) being retrofitted with 155-165 seat psi springs.

Call experienced cam guys with what they'd run for psi's with your set up.

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Another IMHO is anything 650hp or more will make more power with a Dominator.

A 1000HP carb make a motor 'flat line' - not unless it's F*ked up.

Valvetrain, fuel supply, and ignition are biggest causes for a motor to 'flatline' - especially if it's before the where Hp peak shou;d be - again 1200 or so rpm past Torque peak.

those heads are too big for a natural aspirated motor I think the runners are something like 385 motor is lacking air velocity with that big runner

Gotta spin it up then!

720ft/lbs at 4500rpm out of a low compression motor is not lacking low speed torque. He's not carrying torque to a higher rpm. Known as HP.

Right now it's making power for a Hatteras (maybe slight exxageration), not a High Speed Performance Boat.

Copied and Pasted from Brodix's site: http://www.brodix.com/heads/big-bloc...-bb-3-series26

The BB-2 X head works well with a light car or large engine (509-555 cu in). It has a 340 cc intake port and flows over 360 cfm with only the bowls blended and the intake ports matched to the gasket. The BB-2 X may be purchased angle milled to 110 cc or angle machined to 98 cc.The BB-2 XTRA head works well on a 540 cu in or larger engine. It has a 365 cc intake port and flows over 375 cfm with only the bowls blended and the intake ports matched to the gasket. The BB-3 works well on a 540-605 cu in engine. It has a 370 cc intake port and flows over 370 cfm,

these are the 365 runner heads with 126cc chambers I swapped out the cam over the weekend and we r trying again. should be dynoing today or tomorrow