Offshoreonly.com - low compression 548 dyno testing has begun!!

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No big deal.Just making sure. I haven't sent the final ones yet due to a scanner issue. Save time if you want and just look at these final ones and just refer to the earlier ones if you feel the need.

Quote:

Originally Posted by articfriends (Post 4542143)

so a 700 hp motor at 1.05 cf has a friction factor of 5.25 hp added to cf vs observed? sounds about right compared to depac
I think the depac friction factor is slightly more generous or motor doesnt have quite 15% friction as at 2.8% CF am gaining 28 hp from CF at 663 observed when it would be 18.56 actually.
What this means to all the normal guys reading this who are scratching there heads: the higher your CF is on dyno, the less accurate your numbers are PERIOD. At one point Roccard came on here showing a 454 or 502 making 710 + hp w edelbrock 9-1 290 cc heads on 91 octane for sale, problem is he showed bsfc and lbs hr fuel used, motor used like 290 lbs per hr fuel at hp peak at .5 bsfc, he did NOT show CF used. So doing some real easy math, 290 x 2 (being bsfc was .5) is 580, thats how much hp worth of fuel he used at .5 bsfc, the numbers dont lie, so motor made 580 observed hp and was corrected 22.4 %, you would have to be dynoing in a monsoon at 5000 feet elevation to have a 22.4% CF, totally lies and BS, he quickly got ran off this board. You will ALSO notice that some very good looking dyno sheets from well known builders have been posted on OSO thru the years and you will OFTEN see BSFC and lbs per hr whited or blackened out, why, whats to hide??

Sounds like we need a thread devoted just to dynos and correction factors. So if you know the weather conditions you should be able to tell what the correction factor should have been? With the understanding that there are a couple acceptable standards they could be corrected to.

Quote:

Originally Posted by bck (Post 4542239)

Yes I actually started a thread a long time ago on Dyno correction factors and we had quite a discussion I also have went on Weather Underground for a location when somebody published a bogus dyno sheet, looked up all of the weather data looked up the altitude calculated the station pressure calculated the observe air density went on Wallace racing and we calculated what the dyno correction factor should have been. When I called out the very well known engine builder at that time and asked why he had a 16% correction factor instead of the 5% it should have been his answer was they were using very hot attic air to feed the motor

I'm glad I'm not the only dickhead here. :) :lolhit:

my correction factors always seem to be .96-.99.:party-smiley-004:

Quote:

Originally Posted by sutphen 30 (Post 4542583)

my correction factors always seem to be .96-.99.:party-smiley-004:

Ive dynoed with .97 cf before, made best power at about .380 bsfc too, anybody have a idea what it was? (SB, YOUR NOT ALLOWED TO ANSWER)

Quote:

Originally Posted by articfriends (Post 4542101)

You would think yes BUT with depac they read about 9% higher because of this k factor/friction factor

So lets say the HP was 753 corrected on sheet, and 685hp observed. The correction factor listed 1.0736 on sheet.

685 x 1.0736 = 735hp
685 x 1.0836 = 742hp
685 x 1.0936 = 749hp
685 x 1.1035 = 755hp

Seems like while the correction factor was 1.0736, it actually added about 9% to the observed number with Depac. Air Temp listed at 84.6 F, 29.211 baro, SG .751,

:throw: Lets go :boat:

Quote:

Originally Posted by getrdunn (Post 4542610)

:throw: Lets go :boat:

Would be cool, but Braap is still in the air. 8"-12" tonight. Bay ice has thinned down, but still plenty thick for a car at 16".

Quote:

Originally Posted by articfriends (Post 4542586)

Ive dynoed with .97 cf before, made best power at about .380 bsfc too, anybody have a idea what it was? (SB, YOUR NOT ALLOWED TO ANSWER)

rc motor