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Thread: Losing mph when racing 6litre l76

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    Losing mph when racing 6litre l76

    I need some help on why I seem to lose mph when racing, just recently I have dropped from 117mph doin 11.4s to 113/114mph doin 11.6s in a vz SS 6litre my 60 fts are 1.634, my reaction is around .040 running street ets on 15psi, I just seem to be going down in mph my engine sounds normal and not getting much wheel spin and launches well but I'm at loss on why my mph is dropping when I'm pretty much racing with the same setup, the only mods is a cam and stall with 3.9 gears any help would be appreciated, I'm thinking of doin a compression test but the motor was built early 2015 thanks.

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    SPECIAL DARK HOTCIVIC's Avatar

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    You log the density altitude difference between runs?

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    Registered Member Potent68's Avatar

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    As HOTCIVIC said, I'd definitely look at what the weather was doing on those days.

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    DANSBIRD's Avatar

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    Like Potent alluded to, the weather may play a factor in the performance.

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    LIFE IS GOOD HybridZ28's Avatar

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    Compression test and change spark plugs while you are there.

    How's the tune?

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    Registered Member zo6pilot's Avatar

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    Quote Originally Posted by CHASEVZSS View Post
    I need some help on why I seem to lose mph when racing, just recently I have dropped from 117mph doin 11.4s to 113/114mph doin 11.6s in a vz SS 6litre my 60 fts are 1.634, my reaction is around .040 running street ets on 15psi, I just seem to be going down in mph my engine sounds normal and not getting much wheel spin and launches well but I'm at loss on why my mph is dropping when I'm pretty much racing with the same setup, the only mods is a cam and stall with 3.9 gears any help would be appreciated, I'm thinking of doin a compression test but the motor was built early 2015 thanks.
    Quote Originally Posted by HybridZ28 View Post
    Compression test and change spark plugs while you are there.

    How's the tune?
    Nah...I'd go with what Potent and Dan said bro...

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    Registered Member speed_demon24's Avatar

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    How many miles are on the valvesprings?

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    The Sax of Cars Anewconvert's Avatar

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    Have you considered what hotcovic, potent, Dan and hybrid have suggested?

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    Thanks for the replies, I will look into the time slips next week as I fifo at the moment but if I recall the times when I was running 117mph was only a few months ago and was fairly consistent in August track temp was about 21' degrees, where as in November I'm running close to 113/114 maybe a 115 mph if I'm lucky were track temp is 38-42' degrees, so it's a lot hotter but have noticed other racers are still running same if not a little higher than usual also. My engine was rebuilt back in early 2015 which had around 112k on the clock to this date it's on 118k I don't drive to much just mainly race it but it's full street car. That gives an indication how many miles the new engine has done, I replaced with new oil and filter and regularly change plugs to a .040 gap setting and it runs fine throughout with max rev range to 7000rpm. I was just thinking I may have damaged the engine internally for the low mph I am doin so constantly?

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    Team Hobbit windham's Avatar

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    I would consider what anewconvert said.

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    SPECIAL DARK HOTCIVIC's Avatar

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    21 c = 70 f
    38 c = 100 f

    I'm surprised you only lost 3-4 mph.

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    Registered Member STANG KILLA SS's Avatar

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    fun fact: a stock LS(3) starts pulling timing (less HP) when coolant temps reach 212* or idle air temps reach 86*




    my fastest laps times (road racing) always happen on the first lap, before temps rise, and ecu pulls timing.

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    Registered Member Potent68's Avatar

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    *intake air temp

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    Registered Member STANG KILLA SS's Avatar

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    hahahahha yeah, thanks for that catch

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