Jason, was that thing in the .43 range on top too? How high does he spin that?

http://www.compfuelsystems.com/
Hes old school, wealth of knowledge, you need to come over some time and meet him.
On another thread, mild thunder made statement that he wouldnt pay a premium price for a all out one of a kind custom carb , even if there was a guaranteed 20 hp (and theres no guarantee). Myself, as a BLOWER motor guy would completely agree. If i have a boosted motor, its making 1050hp on 92, i put some 93 in, bump timing one degree and make 1080, or i throw my full kill pulleys on, turn fuel press to efi up 3 lbs. You will NOTICE (and i do it myself), when blower motor guys talk about hp, for most part its"my motor makes 900 hp, makes, 1050 hp, makes 1100 hp". When NA guys talk about hp its, my motor makes 637.8 or 691 or what ever!
As a NA guy, HOWEVER, people fight, scratch and kill to find tiny ,incremental gains. This motor is sitting on dyno right now, when i walked away from it the other day it was making 691 corrected hp. Aside from the tb spacer im going to try today, unless i change cam, compression, something major its about maxed out. If a guy said he could rework my tb and drop it back on here and get me 705 or 710, id be all for it!!

Its both really, we all hear "you dont tune for bsfcs". No, you DONT, BUT, I will say THIS, having unlimited dyno time WITH a bsfc/flow meter sitting here I have started to see a few things more CLEARLY. Ok, sure, we dont tune for bsfcs, its strictly a measurement of fuel used and shows how efficient motor really is. Not completely true, mostly true but not completely.
Started out with this dyno project tuning for max hp, until im done and motors going in boat, i dont really care about "fuel safe" afrs, i strictly am tunig for max hp. Think like a drag tune. So I mentioned this previously, motor was tuned in, afrs at wot might be 13.6 or 14, its just a 10 second dyno pull, wont hurt anything. Soooo, we have bsfcs in lower to mid .5s, ooh, wow, motors somewhat efficient . Now lets say we bolt Tims 1050 QF carb on, AS JETTED, afrs are mid 12's (10%richer), wot bsfc climbs to .67 from .57, using 10% more fuel. Damn, motors a piece of inefficient crap right, carbs JUNK, bsfcs just went in trash can. NO, we just drove them up by adding jet to have target afrs that wont melt pistons and drop valve heads. So, NOW to be fair in hp comparison, we start adding jet to norms carb to get SAME target afrs. Now, bsfc with HIS carb goes up to .62, pos needs to go in trash too, its a pig right, NO, we just tuned afrs safe. NOW, lets say i bolt efi on, making pulls, bsfc is .70, motors chuggy, afrs look like crap, YES, i know at that point they need to come down, when i start seeing something in the .6 range on top i know im getting close to before.
Now, lets go BACK to the two carbs, lets say bsfc with carb A is .67 and AFR is at 12.5, with carb B bsfc is .62 at same exact AFRS's, NOW we are seeing a difference in efficiency, something about carb b atomizes the fuel more effectively OR it makes measurably more hp with same amount of fuel for other reasons which says we are making x #of hp per lb of fuel, now we are looking at bsfc's at true efficency

For what it's worth (may not really add anything to what's being learned here) here's a sheet from my 512.
I have a Dale Cubic custom 4150 that wet flows around 870cfm.

When we were on the dyno I called Dale and one of his first questions was "what are the bsfc numbers"? We took several looks at the spark plugs and adjusted the timing and crankcase vacuum, but that was it.

We decided to leave the carb tune be and fine tune it once in the boat with the dual channel O2 sensors hooked up.

Perfect example, your at .51 bsfc at 13.5 at 6300, lets say you decide your target afr in boat should be 12.5 at wot so you add 8% more fuel, your new afr should be about 12.5 and your bsfc would change theoretically 8% to .55, if you went to 12.15 at wot, would be .56/.57 BUT lets ALSO say going to 12.15 from 13.5 kills 5%hp, approx 38, BUT your still using the same 292 lbs per hr PLUS the extra 10% you added, (another 29). Now we take that new minus 38 hp into acct on the bsfc and we now jump from that .57 to just under .600 (remember we lost 5%hp from adding that extra fuel).

So going to start more testing in a little while, disappointing news from norm on rons throttle body and adapter, its 102 mm, not 105. He flowed throttle body at around 900 cfm, not 1500 or 2000 we were led to believe it was. After some grinding and wide open adjustments he got it to flow 1070. Once he bolted it on 4500 90 degree adapter flow dropped under 900 cfm. After doing some clean up on adapter he got flow just over 900. Still going to test it, any guesses as what it will do to hp and tq?

and mefiburn should change the base tune they give out so this doesn't happen to others out there.

also comes down to how accurately your measuring fuel flow.just another measurement that can be fcked w/ to say I have the most efficient porting,,even better than a nascar team.

Been reading up on how the drag guys tune. Doesn't sound particularly applicable to a boat.

The real obsessive NA looking for every HP tune lean and start their Dyno pulls above peak torque to avoid the chance of detonation. They start on C16 then once the tune is close switch to C45 which is only 100 octane!

Their tunes are banking on never being at WOT at or below peak torque!

I actually never started w a tune that came directly from mefiburn, i have tuned stuff on the water that had dtarting tunes from other people that i have kept final copys of afterwards, i have unlocked stock 502, 500efi tunes, i have unlocked ram jet 502 tunes, copys of tunes of my stuff that got dynoed at crocketts etc.
Made some more incremental progress on dyno today too, once i digest and review the data i will post results, i will say the 1"spacer under TB had small positive gains everwhere.