Re: Tire weight?
[Re: emarine01]
#218763
02/09/09 02:35 PM
02/09/09 02:35 PM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
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Romeo MI
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Quote:
How much diff in et could you expect in a tire weight change of 34lbs total, traction being close to equell?
I believe the old rule of thumb is 100 lbs is equal to .1 in the 1/4... based on a 10 or 11 second car. I could be wrong on this
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Re: Tire weight?
[Re: MR_P_BODY]
#218764
02/09/09 02:41 PM
02/09/09 02:41 PM
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Joined: Oct 2004
Posts: 8,165 Left Coast
BobR
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Quote:
Quote:
How much diff in et could you expect in a tire weight change of 34lbs total, traction being close to equell?
I believe the old rule of thumb is 100 lbs is equal to .1 in the 1/4... based on a 10 or 11 second car. I could be wrong on this
You may see a slightly better gain than this since it's rotating weight.
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Re: Tire weight?
[Re: forphorty]
#218769
02/09/09 09:37 PM
02/09/09 09:37 PM
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Joined: Jan 2007
Posts: 3,695 nc
emarine01
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Quote:
with weight loss ,i believe the greater the distance from the axis of a rotating part , the more benefit. meaning, weight removal at the tire will make more difference than an equal amount at the spool, brakes or axles.
So it could be possible that the tire weight is part of the reason were having a slow to rev problem in high gear between 6500 & 7000 rpm with the 34lbs heavyer tire ?
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Re: Tire weight?
[Re: emarine01]
#218771
02/09/09 09:54 PM
02/09/09 09:54 PM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
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Quote:
Quote:
with weight loss ,i believe the greater the distance from the axis of a rotating part , the more benefit. meaning, weight removal at the tire will make more difference than an equal amount at the spool, brakes or axles.
So it could be possible that the tire weight is part of the reason were having a slow to rev problem in high gear between 6500 & 7000 rpm with the 34lbs heavyer tire ?
It is true that the farther out the weight is the more it hurts. Possibly you are just running out of torque to move the weight that far out
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Re: Tire weight?
[Re: emarine01]
#218773
02/09/09 10:11 PM
02/09/09 10:11 PM
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Joined: Oct 2004
Posts: 8,165 Left Coast
BobR
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Quote:
Quote:
with weight loss ,i believe the greater the distance from the axis of a rotating part , the more benefit. meaning, weight removal at the tire will make more difference than an equal amount at the spool, brakes or axles.
So it could be possible that the tire weight is part of the reason were having a slow to rev problem in high gear between 6500 & 7000 rpm with the 34lbs heavyer tire ?
Not likely. I'd look for another cause. Once you get the tires turning they actually act like flywheels between gear changes. The momentum of the tires actually helps get you through the change. Your biggest gain will be in the first part of the track when switching to lighter tires/wheels.
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Re: Tire weight?
[Re: emarine01]
#218776
02/09/09 11:49 PM
02/09/09 11:49 PM
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Joined: Jan 2003
Posts: 6,591 Canton, Ohio
Sport440
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In a Drag race car 1/4 mile tire weight will have less effect. As you are slowly rotating that tire speed from 0 mph to a 120 mph [Example] over the course of 1320' ft.
You on the other hand are mud racing and rotating that tire rather quickly to 120 mph. Once there rotating at about 120 MPH against the resistance of the mud. The extra 34# can add a significant torque resistant in rotation in addition to the mud its trying to rotate in at that tire RPM.
Also At what Diameter are you talking about??
As far as torque goes wider lobe seps reduce the torque peak but will broaden the range of the torque. So you will see Less torque but with the broader range of the torque RPM band you will see more HP. RPM dictates the HP. At 7000+ rpm you are not wrong in adding LS mike
Last edited by Sport440; 02/10/09 12:00 AM.
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Re: Tire weight?
[Re: S/ST 3040]
#218777
02/10/09 10:02 AM
02/10/09 10:02 AM
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emarine01
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We run 414ci 4.060x4" ,1973 59 drgree with steel center caps with studs,12/1 flat tops with W5s 325I@.650 /235E light steel crank with bme 6.123 rod , 58 quench ,1 3/4 schoenfield fenderwells with 3.5 collectors current cam is comp solid roller 260@.050/262 , .630/.631@ 106 on 106 with 1.5s with a BG 850 M1 intake with 1" hollow spacer & 1/2 No2 plate, 727 w/5k conv old cam & carb were cam motion 280/284 -.660/.659 @ .050 107 @103 holley 1050 w/2" adapter the truck is toyota weighs 3500 w/me . with the big cam & light tires we pulled to 7800 with heavy tires 6500 w/small cam pull to 7200 light tires /6500 heavy/tires light 38.5x11.5/ heavy 38.5x 15 / 39.5x16/ we run light 40x17 cut tires but are working on a spring bind problem thats real bad with the cuts , the big cam runs better ets with the light tires / the small cam runs better ets with heavys than the big cam , I know there is a better choise in cams just havent got it right yet
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Re: Tire weight?
[Re: emarine01]
#218778
02/10/09 11:15 AM
02/10/09 11:15 AM
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Joined: Jul 2006
Posts: 4,595 On the south side of Nowhere
S/ST 3040
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Am I reading that right......1/2" nitrous plate? Or 1/2" #2 plate? If you're running nitrous, I'm going to be a little "iffy" on cam selection. I never used it and have limited undersanding as to the changes that optimize the use of the N2o. I do know N2o cams usually have wider LSA and use more exhaust duration because of the extra spent gasses. If you are using N2o, how much? What your changes tell me is, it likes the extra traction of the wider tire, even though the engine won't turn 7800 with them. What gears are you running?
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