Perfect dyno weather today in East County.....
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Perfect dyno weather today in East County.....

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    Resident Ford Nut Sleeper CP's Avatar
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    Default Perfect dyno weather today in East County.....

    Perfect dyno weather for a boat engine that gets used in the middle of the Summer in the desert: 105* @ 82 % humidity.

    If given the choice would you rather dyno your boat engine at 105* @ 82% humidity or 80* @ 70% humidity ?

    S CP
    Last edited by Sleeper CP; 07-19-2010 at 01:04 PM.

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    cfm
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    I'd rather dyno in as close conditions as the engine is going to typically be run in (elevation included) and see the real life operating numbers so we can tune/rig the vehicle to that. That's why I prefer using as local as a dyno as possible while making sure they give me the info I'm looking for. IE: correct info. Motors are to be enjoyed by using them.

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    It didn't take me to long to figure out if you dyno your when it's 78* but run it at the river where it's 108* you just might be off on the tune up.

    I'd rather have lower observed numbers ( the computer can do the correcting) and have the jetting and maybe the timing a bit closer.

    S CP

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    gn7
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    screw dynoing under the conditions your going to run in. You need to built to the conditions your going to run in. Would you really built a 9.5/10.0 to 1 motor if you ran at 7500' physical, and 10,000+ calculated, all summer long.



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    steelcomp was here
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    Quote Originally Posted by Sleeper CP View Post
    It didn't take me to long to figure out if you dyno your when it's 78* but run it at the river where it's 108* you just might be off on the tune up.

    I'd rather have lower observed numbers ( the computer can do the correcting) and have the jetting and maybe the timing a bit closer.

    S CP
    You seldom have the choice as to the dyno conditions, unless you're just going to sit around and wait for that perfect scenario. That's why there are correction factors...so guy at 6500' can build an engine and be able to test it and compare the results with a guy at 500'. (I know you know that...I'm just sayin...)You should be able to reverse the weather info and correct the "corrected" numbers in the same manner to get what your actual HP might be in a given condition, on a given day.

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    Yes you can, when you know where the numbers come from.

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    ^^^

    In 2007 when I dyno'd the C A T was 84* two weeks later when I went to Aha Quin it was 118* and the DA was something like 6,000 + maybe 7,000.

    On the dyno I was already down to 80 pv / 86 jets with A/F of 12.2's. How much more jet would you have pulled out of it?

    The exhaust temps were starting to climb on the dyno.

    S CP
    Last edited by Sleeper CP; 07-18-2010 at 08:57 PM.

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    Quote Originally Posted by Sleeper CP View Post

    In 2007 when I dyno'd the C A T was 84* two weeks later when I went to Aha Quin it was 118* and the DA was something like 6,000 + maybe 7,000.
    are you sure about that? what was the da in the dyno cell? elevation? baro pressure? dew point?
    what's the elevation at aha? and the other readings?

    there's more to da than heat. i remember it being 119 at chow one year, but the da didn't get over 4900. and i've seen over 3000' da with temps in the mid 80s. point is, you're not really gonna know without calc'n it out, or a weather station.

    Quote Originally Posted by Sleeper CP View Post
    On the dyno I was already down to 80 pv / 86 jets with A/F of 12.2's. How much more jet would you have pulled out of it?
    i wouldn't change anything, but that's just me. maybe one number if you just can't stand not changing something.

    that same year at chow, a friend of mine would come back to the pits, pull his plugs. they were dark, so he started downsizing. came back the next time, kept downsizing. i'm like, "dude..." "i know what i'm doin here..." . of course, it was his midrange and idle circuits that he didn't touch all weekend that colored his plugs. fortunately, he didn't kill it in one weekend, but when he got home and told his engine guy what he did, he needed a new ass...

    Quote Originally Posted by Sleeper CP View Post
    The exhaust temps were starting to climb on the dyno.
    just curious, but do you make any full power runs for extended time on the dyno? like, 15-30 seconds at full power?
    Last edited by bp298; 07-18-2010 at 09:38 PM.

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    Hi Bob,



    The dyno corrected max hp to 935 @ 7,000 and 765 lbs ft @ 6,000.

    The air at Aha is horrible, maybe one of the regulars can tell us how bad it is. If I remember correctly Greg Shoe pulled out his air station Sunday morning when I was talking to him and it was over 5,800 I think. He told me the air on the lagoon is worse than out on the river. Actuallelevation is somewhere around 550' I think. It's been 3 yrs, my memory isn't what it used to be.

    I can tell you this, when I got home I called my dyno guy and told him the conditions of Aha and the the engine didn't pull the impeller as well as I thought it might. I aksed him what he thought the observered numbers were that I was seeing at 116-118*. After looking at it he told me I was dealing with a 7% power loss in the those condidtions. Down 56 hp at 6,000.

    I just left the jetting alone, but with the old engine I used to pull 1 jet size for every 10*. But I had a lot more to play with, that engine dyno'd with 92 pv / 96 jets. This engine I pulled 12 jet sizes out, it made 80 more hp using less fuel than on the old 565 set-up.

    No I have not made any prolonged dyno passes, just sweep passes? Have you ever made a 10 second max power dyno pull?

    S CP
    Last edited by Sleeper CP; 07-18-2010 at 11:27 PM.

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    cfm
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    Quote Originally Posted by gn7 View Post
    You need to built to the conditions your going to run in. Would you really built a 9.5/10.0 to 1 motor if you ran at 7500' physical, and 10,000+ calculated, all summer long.
    x2. I agree 100%.

    Just like building a higher compression for altitude motor all to have it used at sea level especially when half the racing or use season is during the fall when there is real good air.

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    Quote Originally Posted by Sleeper CP View Post
    Hi Bob,

    The dyno corrected max hp to 935 @ 7,000 and 765 lbs ft @ 6,000.

    The air at Aha is horrible, maybe one of the regulars can tell us how bad it is. If I remember correctly Greg Shoe pulled out his air station Sunday morning when I was talking to him and it was over 5,800 I think. He told me the air on the lagoon is worse than out on the river. Actuallelevation is somewhere around 550' I think. It's been 3 yrs, my memory isn't what it used to be.
    hi jon. elevation at the airport in havasu is 840, so 550 would probably be very close.
    over the last week, monsoon type weather has been coming up from the south. haven't had any rain or t-storms, but for the last week, humidity has been rising with no drop in air temp. if the air temp is high and dew point starts rising, it drives d/a through the roof. the air temp doesn't have to change much at all to get a significant increase in da.
    in texas, you'd see >70% in the morning, but temps will be down, and as temps rise, humidity drops to the 50% range by noon. tuning in those conditions would bend your mind. these are two significantly different scenarios.

    for a quick and dirty idea of what d/a might be, i use this. http://wahiduddin.net/calc/calc_da.htm
    you can get fairly close data to plug in from weather underground, or combination of weather sites.

    Quote Originally Posted by Sleeper CP View Post
    I can tell you this, when I got home I called my dyno guy and told him the conditions of Aha and the the engine didn't pull the impeller as well as I thought it might. I aksed him what he thought the observered numbers were that I was seeing at 116-118*. After looking at it he told me I was dealing with a 7% power loss in the those condidtions. Down 56 hp at 6,000.
    sorry, that doesn't make any sense to me at all, especially looking at your dyno sheet. how much rpm did you lose, compared to say 3000' da? if your engine dropped from 6300 to 5800 at wot, then it makes sense.

    Quote Originally Posted by Sleeper CP View Post
    I just left the jetting alone, but with the old engine I used to pull 1 jet size for every 10*. But I had a lot more to play with, that engine dyno'd with 92 pv / 96 jets. This engine I pulled 12 jet sizes out, it made 80 more hp using less fuel than on the old 565 set-up.
    so, when you were downsizing every 10 degrees, what did that do to your a/f ratio, before and after? how did that affect performance?

    if i really and truly saw >6000', i'd make a change, but it wouldn't be drastic. really, you have to hunt for conditions like that, and it's usually not going to be at an elevation of 550'.

    Quote Originally Posted by Sleeper CP View Post
    No I have not made any prolonged dyno passes, just sweep passes? Have you ever made a 10 second max power dyno pull?

    S CP
    pretty much every time on the dyno - usually one 13-15 second pull, slightly above the rpm i expect to run.

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    [QUOTE]
    Quote Originally Posted by bp298 View Post
    hi jon.


    sorry, that doesn't make any sense to me at all, especially looking at your dyno sheet. how much rpm did you lose, compared to say 3000' da? if your engine dropped from 6300 to 5800 at wot, then it makes sense.
    I made this 3 yrs ago...


    If I remember correctly I expected the engine to turn 5,800 with Jack's "A" impeller, he told me it would be real close to a AA on this chart ( + a little) So I was expecting 5,800 off the bottle, if the conditions lost 56 hp that put me at 5,700.

    I ran that impeller cut one more weekend and decided I didn't like the 5,800 rpms, so I had Jack cut it so it would rev to 6,200 off the bottle. Lots more fun that way and it changed the high speed cruise rpm by maybe 150 rpm. I sent Jack the dyno sheet above to Jack along with the impeller and what do you know, it pulls to 6,200.

    so, when you were downsizing every 10 degrees, what did that do to your a/f ratio, before and after? how did that affect performance?
    Lord only knows But the plugs looked good. The performance was the same. That engine ran 13.0- 13.5 air fuels on the dyno.

    if i really and truly saw >6000', i'd make a change, but it wouldn't be drastic. really, you have to hunt for conditions like that, and it's usually not going to be at an elevation of 550'.
    If I recall that weekend was extremely hot and extremely humid. Bad weather for HP that weekend.


    pretty much every time on the dyno - usually one 13-15 second pull, slightly above the rpm i expect to run
    Got video

    S CP
    Last edited by Sleeper CP; 07-19-2010 at 11:25 AM.

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    fast is the other half.
    " A Government big enough to give you everything you want is big enough to take away everything you have"

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    cfm
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    Quote Originally Posted by Sleeper CP View Post
    It didn't take me to long to figure out if you dyno your when it's 78* but run it at the river where it's 108* you just might be off on the tune up.

    I'd rather have lower observed numbers ( the computer can do the correcting) and have the jetting and maybe the timing a bit closer.

    S CP
    A little extreme example, but here we snowmobile. Problem is, is that if you build a motor you do so before the season starts of course. Nothing like dynoing middle to end of summer (or real wamr fall) all to try to get #'s and tune for our normal -20°F to +20°F winter riding conditions.

    And then, of course, the correct #'s are calculated to the same weather specs as our auto/boat engines. -20°F is just a tad different than +77°F.

    Makes it tough for engine and clutch tuning from dyno info.

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    Yeah there is a fair interest in snowmobiling up in the higher country where they regularly run into conditions of 11,500'MSL and temps of way low, but most of the more serious folks use inlet heat at the lower temps.

    If you know where the numbers come from and can get pretty good estimations of where the engine is going one can make some very good estimations on tuning from the differential in the weather. Assuming the fuel in a known issue.

    Sleds with EFI are certainly more forgiving than the carbureted rigs of old.

    With boats that fuel thing is also problematical as "marina fuel" is all over the map for carbon and water content.

    Regards,
    IG

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