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Overgeared?

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Old 05-14-2005, 06:07 PM
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Default Overgeared?

Ok I think I'm overgeared. Car is not getting decent E.T.'* at all....well not compared to what I should be getting. I've added a lot to the car since my best run, which should have lowered my E.T.'*. However, one thing I did change that could have a negative effect are the Nitto 245/50/16 tires. Is it possible that these small little guys are spinning way too fast and overworking the engine...kinda like overgearing it.

I suspect I should go back to stock 225/60/16 tires on these rims. Anyone?
Old 05-14-2005, 06:19 PM
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I don't think those will hurt you. You have MORE then enough power to push a 2.97 Gear ratio IMO, a 245, 50 series is decently close to the 225 60. What where the differences in conditions, etc?

Got your Previous PB and the new run slips or #'*?
Old 05-14-2005, 07:28 PM
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I think you mostly are dealing with heavier tires.
Old 05-14-2005, 07:50 PM
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Do OBD2 computers shift according to engine speed or actual speed(mph)? If it'* actual speed then your shifting sooner due to the smaller wheel/tire. That might slow you down.
Old 05-14-2005, 09:03 PM
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The tire size will not effect shift points, this is done with load and engine speed (rpm).

Hows your torque convertor feeling any slip or vibration?

I swear after I got the cai and high ratio rockers that my time fell off even though I was making more power? I was blaming wheel spin but now think the tranny was on the way out even then and it was just a mater of time?
I'm heading to the track in the next few weeks with the only upgrade from last summer being the new tranny, I'll see soon enough
Old 05-14-2005, 09:51 PM
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Originally Posted by PontiacDad
The tire size will not effect shift points, this is done with load and engine speed (rpm).
I'm under the impression (atleast for the 90'* generation) that throttle position and vehicle speed equate to shifting? I've heard it is possible to go WOT and bounce off redline with a different enough gearing?
Old 05-14-2005, 10:44 PM
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This might be a combination of the tires and maybe my headers hitting the firewall...even tho I pounded the firewall some before putting them on...

Guess what we get to do at the MN meet?! HAHAHA!
Old 05-14-2005, 11:28 PM
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The throttle posistion should play a role but where I was thinking the Intense pcm upgrade raises the shift points based on rpm?
If the headers are hitting could this be causing false knock? Have you scanned for knock?
Old 05-15-2005, 03:08 PM
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Originally Posted by PontiacDad
The throttle posistion should play a role but where I was thinking the Intense pcm upgrade raises the shift points based on rpm?
I know that my shift points were changed according to vehicle speed. But i'm not OBD2.
Old 05-15-2005, 06:42 PM
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Ya I get knock, sometimes upwards of 4. However, when I put 104 octane in at the track its gone within a few passes with the exception of maybe a blip of .1 or .3 here or there.

Something it hitting...cause under hard acceleration I get quite a bit of KR. I blame the headers maybe hitting the firewall and my motor mounts. We Bonnies need poly motor mounts...someone needs to market them.



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