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Tire weight? #218762
02/09/09 01:54 PM 02/09/09 01:54 PM
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emarine01 Offline OP
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How much diff in et could you expect in a tire weight change of 34lbs total, traction being close to equell?
Re: Tire weight? [Re: emarine01] #218763
02/09/09 02:35 PM 02/09/09 02:35 PM
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Romeo MI
MR_P_BODY Offline
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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
Re: Tire weight? [Re: MR_P_BODY] #218764
02/09/09 02:41 PM 02/09/09 02:41 PM
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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.
Re: Tire weight? [Re: BobR] #218765
02/09/09 04:41 PM 02/09/09 04:41 PM
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emarine01 Offline OP
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Its the rorating weight that I am more intrested in , trying to figure in rotating weight and high rpm , IE / how much slower is a heavey tire to turm up in high gear than light tire , all our tires are pretty heavy tire & rim combos are over 100lbs each
Re: Tire weight? [Re: emarine01] #218766
02/09/09 04:48 PM 02/09/09 04:48 PM
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BROOK PARK, OH
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Back when I had my 66 ply I swapped out the 4 wheel drums for wilwood discs and the sure grip for a spool and IIRC dropped .3 off my 1/4 et. I was amazed till one of the old timers told me that I had dropped a ton of rotational weight and what he said was every 10#'s of rotational weight was equal to 100#'s of static weight.

Re: Tire weight? [Re: WILD BILL] #218767
02/09/09 05:19 PM 02/09/09 05:19 PM
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emarine01 Offline OP
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Well that might make sence , with the heavy tires we lost 2.5 tenths and been trying to recover it with tuning, most of the big tire rigs are running over 100+ cubes more than us.
Re: Tire weight? [Re: emarine01] #218768
02/09/09 08:08 PM 02/09/09 08:08 PM
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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.
Re: Tire weight? [Re: forphorty] #218769
02/09/09 09:37 PM 02/09/09 09:37 PM
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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 ?
Re: Tire weight? [Re: emarine01] #218770
02/09/09 09:49 PM 02/09/09 09:49 PM
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Grand Haven, MI
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1976 Spinnaker White Plymouth Duster, /6 A833OD
1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!***
2011 Toxic Orange Dodge Charger R/T
2017 Grand Cherokee Overland
2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
Re: Tire weight? [Re: emarine01] #218771
02/09/09 09:54 PM 02/09/09 09:54 PM
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Romeo MI
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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
Re: Tire weight? [Re: MR_P_BODY] #218772
02/09/09 10:02 PM 02/09/09 10:02 PM
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emarine01 Offline OP
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Thats exactly what it feels like, we turn the piss out of the light tires , same dia & 4" narrower, On paper my small block is still maken hp to 7k but the torque is long gone, thats why weve been looking at cams with wider lsa to see if we could move the torque up higher
Re: Tire weight? [Re: emarine01] #218773
02/09/09 10:11 PM 02/09/09 10:11 PM
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Left Coast
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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.
Re: Tire weight? [Re: BobR] #218774
02/09/09 11:00 PM 02/09/09 11:00 PM
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The problem starts 500 rpm after the 2-3 shift , we shift @ 6k trying to keep the wheel speed up and spinning ,Mud racing , we run around twice the wheel speed <120mph> than the truck is going <60>
Re: Tire weight? [Re: emarine01] #218775
02/09/09 11:25 PM 02/09/09 11:25 PM
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On the south side of Nowhere
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S/ST 3040 Offline
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IIRC, you run W-5s on a 3.79" shortblock. How about a complete
run-down on the engine and vehicle?

I'd have to guess, you're running out of engine in high gear.
You are probably getting the tires up to a speed where they
are cleaning themselves pretty good and the added 4" width
per tire is getting more traction than the engine can pull the
truck.

We need a mud-slingin' smiley.
Re: Tire weight? [Re: emarine01] #218776
02/09/09 11:49 PM 02/09/09 11:49 PM
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Canton, Ohio
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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.
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 Offline OP
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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
Re: Tire weight? [Re: emarine01] #218778
02/10/09 11:15 AM 02/10/09 11:15 AM
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On the south side of Nowhere
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S/ST 3040 Offline
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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?
Re: Tire weight? [Re: S/ST 3040] #218779
02/10/09 12:25 PM 02/10/09 12:25 PM
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emarine01 Offline OP
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We have a plate system with a 150 shot installed but havent sprayed yet , we used it on our old engine, havent realy needed it with new eng, if we run mod class we can spray with the cut tires, we run 3.90x2 to 1 gearing just under 8 t 1 in high gear , you may be right the engine cant pull the extra traction & weight with current set up , my torque is good up to 6k 550lbs than realy dumps by 7k 470lbs on paper ,
Re: Tire weight? [Re: emarine01] #218780
02/10/09 12:50 PM 02/10/09 12:50 PM
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S/ST 3040 Offline
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"270º/274º @ .050" .704"/.660" 108º LSA/ installed 104º"

I remembered discussing cams one other time so, I searched for my
recommendation. I'll stick to it but add 4º to exhaust lobe if you're
going to put the N2o to it.

I'd also use a header with 1 7/8" primaries.

Let's see a picture of that thing.
Re: Tire weight? [Re: S/ST 3040] #218781
02/10/09 01:08 PM 02/10/09 01:08 PM
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emarine01 Offline OP
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The cam sounds about right , Ive been holding back on the cam cause same specs as yours but on a 110 installed on a 106 keeps coming up and I havent figured it out yet, Ill try some pics but thier not too good
Re: Tire weight? [Re: emarine01] #218782
02/10/09 01:11 PM 02/10/09 01:11 PM
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emarine01 Offline OP
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Another bad pic

5014817-12-29-08_1515.jpg (106 downloads)
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