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Old 05-14-2005, 07:07 PM   #1
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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?
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Old 05-14-2005, 07:19 PM   #2
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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 #'*?
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Old 05-14-2005, 08:28 PM   #3
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I think you mostly are dealing with heavier tires.
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Old 05-14-2005, 08:50 PM   #4
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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.
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Old 05-14-2005, 10:03 PM   #5
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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
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Old 05-14-2005, 10:51 PM   #6
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Quote:
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?
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Old 05-14-2005, 11:44 PM   #7
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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!
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Old 05-15-2005, 12:28 AM   #8
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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?
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Old 05-15-2005, 04:08 PM   #9
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Quote:
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.
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Old 05-15-2005, 07:42 PM   #10
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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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