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598 ENGINE, PUMP GAS MOTOR.AFR 385 CNC PORTED HEADS, SINGLE CARB. 10.1 COMPRESSION ON OUR DYNO ( SUPERFLOW 902) IN THE WINTER COOL AIR MADE 801 HP UNCORRECTED. SISTER ENGINE SAME EVERYTHING DYNOED SAT. ONLY MADE 701.....I KNOW THE AIR IS ALOT WARMER AND BAROMETRIC PRESSURE ETC. BUT 100 HP?????? i THINK I AM GOING TO PUT THE FIRST ENGINE BACK ON THE DYNO AND CHECK AND SEE IF IT CHANGED THIS MUCH ALSO .WHAT DO YOU THINK?
 

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598 ENGINE, PUMP GAS MOTOR.AFR 385 CNC PORTED HEADS, SINGLE CARB. 10.1 COMPRESSION ON OUR DYNO ( SUPERFLOW 902) IN THE WINTER COOL AIR MADE 801 HP UNCORRECTED. SISTER ENGINE SAME EVERYTHING DYNOED SAT. ONLY MADE 701.....I KNOW THE AIR IS ALOT WARMER AND BAROMETRIC PRESSURE ETC. BUT 100 HP?????? i THINK I AM GOING TO PUT THE FIRST ENGINE BACK ON THE DYNO AND CHECK AND SEE IF IT CHANGED THIS MUCH ALSO .WHAT DO YOU THINK?
What were the differences in DA? Anything different about the engines? Cold dense air to hot thin air on a 598 could net 100hp. You betcha.
 

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Jim, my guess is that you would not see the same percentage drop from a 350 with a 2.02 intake. When the engine gets that big, and the intake is that under sized, the smallest hinderance in air quality hits it hard. 385 may seem like a big head, but the things are probably still carrying a 2.30 valve and there is your choke. I don't think an engine with a better cid VS intake valve area would suffer as much. JMO

Steel should have said cool "DRY" dense air, VS warm "HUMID" thin air. Might as well make it ugly. And it doesn't have to be as bad as you might think. It it was as easy as "wow its a nice day" compared to "god its hot and sticky" we wouldn't need to carry weather stations.



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598 ENGINE, PUMP GAS MOTOR.AFR 385 CNC PORTED HEADS, SINGLE CARB. 10.1 COMPRESSION ON OUR DYNO ( SUPERFLOW 902) IN THE WINTER COOL AIR MADE 801 HP UNCORRECTED. SISTER ENGINE SAME EVERYTHING DYNOED SAT. ONLY MADE 701.....I KNOW THE AIR IS ALOT WARMER AND BAROMETRIC PRESSURE ETC. BUT 100 HP?????? i THINK I AM GOING TO PUT THE FIRST ENGINE BACK ON THE DYNO AND CHECK AND SEE IF IT CHANGED THIS MUCH ALSO .WHAT DO YOU THINK?

do you recall the temp change......the D/A would be great but just the air temp would be good to know.

After I dyno'd the engine in '07 two mid 80's temp ... 2 weeks later ran it at the river and it was 115* that weekend, I called my dyno guy and he figured I was down 75-80 hp observed.

I don't think 100 is out of the question from what I saw that weekend.

S CP
 

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Jim, my guess is that you would not see the same percentage drop from a 350 with a 2.02 intake. When the engine gets that big, and the intake is that under sized, the smallest hinderance in air quality hits it hard. 385 may seem like a big head, but the things are probably still carrying a 2.30 valve and there is your choke. I don't think an engine with a better cid VS intake valve area would suffer as much. JMO

Steel should have said cool "DRY" dense air, VS warm "HUMID" thin air. Might as well make it ugly. And it doesn't have to be as bad as you might think. It it was as easy as "wow its a nice day" compared to "god its hot and sticky" we wouldn't need to carry weather stations.
The AFR's have a 2.35 intake but your point is still valid. There really isn't a conventional off-the-shelf head available with a big enough intake valve for these 600" engines, evne with 10:1 and a single carb. At least not IMO.
 

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Discussion Starter #6 (Edited)
The AFR's have a 2.35 intake but your point is still valid. There really isn't a conventional off-the-shelf head available with a big enough intake valve for these 600" engines, evne with 10:1 and a single carb. At least not IMO.
yea they are 2.350 intake and the cfm of air were 1055 at 6100 both exactly the same the graf lay over exactly the same except down 100 hp motor are built with exact same parts , same carb too. i'll check the data for the temp. I just coulded believe that much on well.
 

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Discussion Starter #7
What were the differences in DA? Anything different about the engines? Cold dense air to hot thin air on a 598 could net 100hp. You betcha.
den alt feet first eng was -405 second engine 1,912 ????? AIR DEN .077 / ,073 HUMIDITY 40.7 / 47.3 AIR TEMP 50. DEGREES / 79.6 BARO P 29.81 / 29.68
 

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Just guessing. But if both dyno sheets lay over exactly the same, most likely the DA/weather that day. 100hp drop isnt out of the question as mentioned before here.
 

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den alt feet first eng was -405 second engine 1,912 ????? AIR DEN .077 / ,073 HUMIDITY 40.7 / 47.3 AIR TEMP 50. DEGREES / 79.6 BARO P 29.81 / 29.68
2300' swing in DA, but mineshaft air on the first one. :D
Have you done the corrected on both engines? How close are they? That should give you some of your answer.
 

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Discussion Starter #10 (Edited)
2300' swing in DA, but mineshaft air on the first one. :D
Have you done the corrected on both engines? How close are they? That should give you some of your answer.
corrected first one 801.1 to 800.8 hp nothing really second engine 670 hp to corrected 718 hp little more ( Dave Blackburn at superflow said the same thing but did not correct that much to make up the difference , sent him a fash drive of both pulls and he says the first one does not look right to him... I guess I,ll just have to put the orginial engine back on the dyno and see maybe he's right. it doesn.t make much sense to me but I want both of them to be the same when they go into the boat. it,s only my pleasure boat anyway. we had a pair of 600 hp engines in it before. wanted to bump it up a notch. but if all that expense for 100 hp ( 200 total ) it wasn.t worth it. except the piece of mine that they are all new. ( this was the last pull that we did today..) 718 corrected
 

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Discussion Starter #11 (Edited)
2300' swing in DA, but mineshaft air on the first one. :D
Have you done the corrected on both engines? How close are they? That should give you some of your answer.
why is that DA -405??? backburn says the .44 on the BSFC DOESN'T LOOK RIGHT TO HIM ON THE FIRST ENGINE??
 

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why is that DA -405???
That's called "mineshaft air" meaning it's well below sea level conditions (really good air for making power). With that DA I would have expected a little more correction on the first run. Maybe that's what Dave was referring to, but that wouls also increase the difference between the two engines.
I'm a little confused though...your first post said the 701 and 801 numbers were un-corrected. I could see that 100 hp difference in uncorrected numbers, but corrected numbers should take into account the different weather conditions and should be very close if the engines are truly identical (as possible).
 

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I would do a leak down test

And recheck all the valve and timing settings

just to be sure

I love to boat the Delta, cold sea level air in the summer and damm cold in the winter

Mark Twain once said the coldest winter I spent was the summer in San Francisco
 

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corrected first one 801.1 to 800.8 hp nothing really second engine 670 hp to corrected 718 hp little more ( Dave Blackburn at superflow said the same thing but did not correct that much to make up the difference , sent him a fash drive of both pulls and he says the first one does not look right to him... I guess I,ll just have to put the orginial engine back on the dyno and see maybe he's right. it doesn.t make much sense to me but I want both of them to be the same when they go into the boat. it,s only my pleasure boat anyway. we had a pair of 600 hp engines in it before. wanted to bump it up a notch. but if all that expense for 100 hp ( 200 total ) it wasn.t worth it. except the piece of mine that they are all new. ( this was the last pull that we did today..) 718 corrected
what's the altitude where the dyno sits? also, do you know what the dewpoint was during the two tests??
 

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Discussion Starter #16
I would do a leak down test

And recheck all the valve and timing settings

just to be sure

I love to boat the Delta, cold sea level air in the summer and damm cold in the winter

Mark Twain once said the coldest winter I spent was the summer in San Francisco
did that everything good
 

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Discussion Starter #17 (Edited)
Were the 2 engines jetted the same? Because if they were, and the jetting on the first was dead on, the second would rich.
Or was the second engine jetted to best power while strapped to the dyno?
If you ran the jetting/timing loop on the first engine and just duplicted on the second, you could be less the "best" for the conditions for the second engine.
was the same and then changed it not much difference leaned it out did help a little
 

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Discussion Starter #18
That's called "mineshaft air" meaning it's well below sea level conditions (really good air for making power). With that DA I would have expected a little more correction on the first run. Maybe that's what Dave was referring to, but that wouls also increase the difference between the two engines.
I'm a little confused though...your first post said the 701 and 801 numbers were un-corrected. I could see that 100 hp difference in uncorrected numbers, but corrected numbers should take into account the different weather conditions and should be very close if the engines are truly identical (as possible).
my fault that 701 was on the corrected sheet.. 801 was uncorrected/ 800 corrected
 

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the cfm of air were 1055 at 6100 both exactly the same .
Good info.

Therefore we know nothing was botched like inadvertently installing different cam, heads, wrong motor, LOL. Carbs where opening the same, etc,etc.

How about the fuel flow figures between the two ? If it has A + B figures, please include both seperated.

Wideband readings ?
 
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