carb question
 

if the bsfc is supposed to be around .465 and an engine is dynoed at .745 what could be the problem, the air flow ratio is 12.6 is all the extra fuel going to go in the crank case or will it burn it, ive talked to some guys and they say theres a problem and the builder of course says its ok im at three to one odds, 3 who say theres a prob and one who says its ok.i would like to know what you guys think.i do not want to install these just to have to pull them back out cause theres a problem and washed out the bearings.

N/a sounds like a pretty inefficient motor. What's the specs?

Since the A/F is correct, you would tend to believe the fuel is being burned. In my experience A bad BSFC really points to something in the setup of the engine, cam timing, ign timing, severely mismatched components, etc. something way off in the engine build. It also could be a calibration issue with the dyno or fuel flow meter. Fuel burned is usually a very good indicator of the power the engine is really making. If the dyno was reading low it would make the BSFC incorrect. What was your observed HP reading on the dyno and what correction factor? BSFC is based on raw power, not corrected.

Bob Lloyd
Full Throttle Marine

the engines are talldeck 540s, brodix heads, 10.2.1 compresson, hyd roller 611,631 lift, 1050 dominator, the builder said i should quit worrying about it and install it in the boat. the engine was supposed to make 700hp but only made 620hp, had lots of carb problems at first couldnt get the engine to pull any fuel had to choke the 1150s down. im not going to lie, i can do almost anything to the boat myself but when it comes down to this im LOST!!

I'm not a carb guy, but that sounds like a lot of carb for a 620 hp motor.

Scan your dyno sheets and let us see your actual fuel used numbers/un-corrected hp. IF base hp ISN'T shown we can calculate observed hp from your fuel numbers. Yoou don't tune motor for BSFC, you tune it for egt/afr/knock/plug color/egt's and hp/tq. BSFC's in the mid 7's tells me either the data is all screwed up/un-reliable or your motors are terribly in-effiecient, post your dyno shets, Smitty

What do you mean by "choke the 1150s down"?

was told they converted them to 1050s

I don't see the BSFC or correction factor on the dyno sheet. However, it appears to be burning around 290 lbs/hr of fuel at peak HP. If you divide that by the .745 BSFC you mention it comes out to around 390 uncorrected HP(not very likely). But, if you use .48 BSFC which is in the area it should be it comes out to 600 uncorrected HP. I'm thinking they just have the formula messed up for the calculation in the dyno program. Fuel consumption looks pretty reasonable. If you don't have the correction or observed data, post the location it was dyno'd at and I can look up weather data and altitude for that date and get a pretty good idea of what it should have been.

Bob Lloyd
Full Throttle Marine

Do you have the cam card? At 10.2:1 and with todays heads and cams it is kinda hard not to accidentally make more than 617HP with a 540 (1.14HP/cu.in.) Was this dyno'd with full accessories and wet marine exhaust? That can make a huge difference compared to no accessories and dyno headers.

Am I wrong for thinking this??

cam card
 

i think its to small myself, if you look at teagues site this is a stageII they should had went with a stage III or something closer to that, ive spent a ton of money and was told these engine would make 700hp more or a little less, not alot less. and the bad thing is all he says is my brodix alum heads are old tech, if i put on new heads it would make more power,hell these came off of 580ci motors i think if they made power there they should make power here. i havent put them in the boat they sounded good on the dyno just wasnt happy with the hp and the numbers on the dyno really pissed me off, was told with what i had and the cam he chose that they should make more power, the builder blames everything but his choice of cam. if you were charged 16.000.00 to build to 540s and was told 700hp was no prob then they made 620hp and all they had to buy was the cam, intake, and normal crap as rings, bearings and gaskets.

fixx
 

have bob madara build you a cam and re dyno the engine..if anyone can find the 80 hp its him..they look like blower cams

I think they are but i didnt order those i wanted something that sounded nasty and made some power.

fixx
 

cam card reads crower cams...dod uses bullett or cam motion i think..

no i meant i think they are blower cams, i should had called bob first.

You need to ask how the compression ratio was calculated then check it yourself. Checks out right then the rings didn't seat. Diamond pistons has a comp ratio calculator on their website. Good Luck

I just finished up a pair of 572's and both motors made just over 740hp and a little over 760trq. This was with dyno headers. Garry Williams did the carbs and Danny at cam motion ground the cams for me. Mine have the old style dart 360 heads that we cleaned up in the grinding room. I really think you should be making more power than you are. Brodix makes great heads so I wouldn't blame them just yet. If you'd like you can give me a call and I can tell you a little more about what we did. 985-981-7491. Good luck. Michael

Ive said it before with this build, those cams are not ideal for a 540CI N/A. Bolt a blower on them and it will make some power. 114LSA with the duration numbers is not gonna be '''nasty'' sounding cam in a 540. Nor is it gonna make the power you're looking for. It peaked at 5600RPM. To get 700+ your gonna need to spin that 540 faster.

Keep in mind your gonna want dry exhaust if you step it up to a 700hp cam. Theres nothing wrong with the Dominator carb on that engine. However, your not taking advantage of a dominator carb at only 5500RPM. Don't believe what they tell you the compression was. Unless the heads were cc'd, and proper measurements taken of deck height, head gaskets used, etc, its just a guess. For all you know you might be 9.5:1.

Need to know which Brodix head your running and what was done to them. A BB2xtra will support almost 800hp.

Just for giggles, I put your specs into the desktop dyno program. Used your cam spec's off your card you posted.

Using all that, and the Brodix BB2, and BB2 Plus flow files I had, I came up with 595HP@5500. With no other changes, but switching to a Dart 310 Pro 1 CNC file, power jumped to 644HP@5500. Dart 325CC pro 1 was 643HP@5500.

Switching to this cam with the dart 310 pro 1, 698HP@6000. http://www.race-mart.com/Crane_Cams-416455.html

That cam with the BB2 brodies 650HP@6000. still a 55HP gain over the cam you have with the bb2 profile. granted its a bs computer program, but still fun.