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-   -   Dyno Results: 502 w/ AFRs (https://www.offshoreonly.com/forums/do-yourself-boating-budget/312084-dyno-results-502-w-afrs.html)

242LS 05-12-2014 05:35 AM


Originally Posted by SB (Post 4120630)
I look at CFM #'s a lot. Of course I do. Ooops, forgot I'm SB here. Normal name is CFM.

Anyway - anyone notice this Motor could have used more carb ? Also, it looks like the carb had difficulties keep a half way linear A/F ratio.

The A/F ratio on the sheet appears not be to a wideband, but thru the fuel meter vs Air meter. So , the ratio is not what was actually used by engine but you can look at it to see peaks and valleys. Seems to flutter. Could be the carb itself, but I see the same sort of trends on carb's that aren't sized the way the motor wants.

Seems to be some power left in the carb dept. Not just WOT.

Just letting out some thoughts from my own couch / armchair on the internet. LOL.

Those at not the babblings of a mad man.... Bob Madara told me I'd need more carb. He suggested 950-1000 CFM. They were new last summer, so I didn't want to spend more money on a new set.

Unlimited jd 05-12-2014 06:00 AM

I had brought my 1000 cfm pro systems carb but since we made the power we were looking for and even if it picked up 30 hp new carbs aren't in the budget, we left it as is. Those are calculated air fuel numbers from the air and fuel flow data.
Rotating assembly is hp500.

tpabayflyer 05-14-2014 10:48 AM

I would say you hit your goals perfectly..... Any more power might work against you if you are using a Bravo 1! Decent dock manners, 600HP/TQ, I would say this is pretty much the default 502 upgrade!

242LS 05-14-2014 12:54 PM


Originally Posted by tpabayflyer (Post 4121883)
I would say you hit your goals perfectly..... Any more power might work against you if you are using a Bravo 1! Decent dock manners, 600HP/TQ, I would say this is pretty much the default 502 upgrade!

Yep. I'm happy with the results. I was hoping to keep it "Bravo 1 friendly"!!

ezstriper 05-15-2014 06:43 AM

Nice !

Rookie 05-15-2014 09:23 AM


Originally Posted by SB (Post 4120630)
I look at CFM #'s a lot. Of course I do. Ooops, forgot I'm SB here. Normal name is CFM.

Anyway - anyone notice this Motor could have used more carb ? Also, it looks like the carb had difficulties keep a half way linear A/F ratio.

Just letting out some thoughts from my own couch / armchair on the internet. LOL.

I by no means am an expert at reading dyno paperwork. But isn't the low (lean) 0.39-0.42 BSFC in the heart of the torque curve making anyone else a little nervous? Not an expert, but that is where I was told to be concerned.

MILD THUNDER 05-15-2014 09:33 AM

I think alot of guys today are still going off the carb sizing thought process from 1985. The modern high performance marine engine is a far cry from a 400hp mercury 454 cyclone or a hopped up 330. We are now seeing N/A engines making 600, 700, 800hp. A 465hp HP500 ran just fine with a 800 holley. That's 465hp at 5200rpm. A far cry from 600hp at 6000rpm.

Or there are guys running N/A 540's hoping to make 700hp but want to keep a stock 800 holley on it. I think it goes back to the days when everyone threw a dominator on a 400hp engine and wondered why is was a turd.

mike tkach 05-15-2014 09:44 AM

did he say TURD,lol.

MILD THUNDER 05-15-2014 09:49 AM

Was not insinuating this engine is undercarbed, just a statement regarding a trend I See on oso

Cole2534 05-15-2014 10:20 AM

I wonder if the the factory EFI from a '96 502 mag would support that HP?


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