How did i lose 5mph?
04-15-2004, 09:56 PM
#1
Staging Lane
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How did i lose 5mph? Ok heres the story, i recently had the car dynoed and it did 407 rwhp/387rwtq. I went to the track and it trapped 118 (on average). I was shifting at 6700 then. The dyno showed that my hp dropped off significantly after 6500 rpm so i now shift at 6500. I recently changed the springs and went to TR-6 plugs gapped at .035 from the TR-55's that i used on the 118 mph traps. I only trapped 113 today and 109 with the cutouts closed!! Car seems to run fine, no KR no nuthin.Any one got any ideas where my 5mph could have went? Could the plugs be costing me that much? thanks
04-15-2004, 10:31 PM
#2
where did your hp peak at? if it peaks at 6500 and drops off your not supposed to just shift at 6500 one way or the other you would "want" to shift at 6700-6800ish...i put want in parenthasis(sp?) because i dont think the stock rod bolts would hold for all that long lol. Hopefully that is the anwser to your woes other than that i dunno what to tell ya.
lata
Bill
lata
Bill
04-15-2004, 10:34 PM
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hmmm weird, first of all the plug gap at .035 seems kinda small for those plugs I would try them at .045-.050 and you usually want to shift 200-300 rpm's past your peak power, this puts you back into the sweet spot when you do shift. Still I wouldn't think that would affect you by 5mph, that's a pretty big diff.
-Sly
-Sly
04-15-2004, 10:36 PM
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Originally Posted by foff667
where did your hp peak at? if it peaks at 6500 and drops off your not supposed to just shift at 6500 one way or the other you would "want" to shift at 6700-6800ish...i put want in parenthasis(sp?) because i dont think the stock rod bolts would hold for all that long lol. Hopefully that is the anwser to your woes other than that i dunno what to tell ya.
lata
Bill
lata
Bill
-Sly
04-15-2004, 11:28 PM
#5
Staging Lane
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Originally Posted by foff667
where did your hp peak at? if it peaks at 6500 and drops off your not supposed to just shift at 6500 one way or the other you would "want" to shift at 6700-6800ish...i put want in parenthasis(sp?) because i dont think the stock rod bolts would hold for all that long lol. Hopefully that is the anwser to your woes other than that i dunno what to tell ya.
lata
Bill
lata
Bill
thats my dyno sheet. I have a forged bottom end so im not worried about 7k revs. I changed the springs because i thougth it could be vavle float because of how drastically the cam drops off. Its suppose to peak at 6700 but as you can tell it peaks around 6200. I figured id at least get the same mph not slower though? Any more ideas?
04-15-2004, 11:29 PM
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Originally Posted by slyws6
hmmm weird, first of all the plug gap at .035 seems kinda small for those plugs I would try them at .045-.050 and you usually want to shift 200-300 rpm's past your peak power, this puts you back into the sweet spot when you do shift. Still I wouldn't think that would affect you by 5mph, that's a pretty big diff.
-Sly
-Sly
