Weight of wheels-Impact on 1/4 mile times.

02LSE96LSC91SE84TC

02LSE96LSC91SE84TC

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I ran my 96LSC last summer and had terrible 60 foot times and weak end numbers too. I have 18x9.5 Y2k Cobra rims with 265/40 Bfg KDW tires. They don't stick that great but what really caught my attention was when I installed them, they weighed so much more than stockers. 60lbs vs. 45lbs for stock silver 10 spoke rims with mich. pilots. On the street I didn't notice a speed differance, just that big wheel feel thats normal. How much do they slow me down? BTW they look incredible, and now I'm so used to them the stockers look like temp spares to me.
 
Got any pics, that must look freakin great! Do you have mustang hubs, or did they come in the mark bolt pattern?
 
18" probably made your tires taller (literally, the height of the tire) which effectively raised your gearing. This makes your car slower.

15lb of extra weight on each wheel means a total of 60lb of unsprung weight added to your car!

Im not gonna talk out of my ass and throw you some number like the guy above me, but you can bet your ass your car with the new wheels is a dog compared to your old wheels.
 
PioneerCrazed said:
Got any pics, that must look freakin great! Do you have mustang hubs, or did they come in the mark bolt pattern?
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Sorry no pics to post. Its in the garage for winter and dirty, not exactly photo worthy. Winter came early this year. I intend to post many pics in the future as I do have some cool stuff. They're the Mark pattern and from what I have seen nobody seems to have them anymore. I chose the Y2K's to be alittle different from the normal Cobras. I think they look great also.
 
seanklsc said:
18" probably made your tires taller (literally, the height of the tire) which effectively raised your gearing. This makes your car slower.

15lb of extra weight on each wheel means a total of 60lb of unsprung weight added to your car!

Im not gonna talk out of my ass and throw you some number like the guy above me, but you can bet your ass your car with the new wheels is a dog compared to your old wheels.
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The tires are actually about 1/2 inch shorter than stock. Taller wheel, lower profile tire.
 
mespock said:
What I was told is the Mark VIII runs best on it's 16s and the snowflakes which are the lightest of the Mark VIII rims.

Correct me if I'm wrong....
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I can't disagree.
 
I love the Y2Ks! I wish they still made them, cause id probably buy some. When you can,.....Get some pics man!
 
60' 2.562
1/8 10.174@73.83
1/4 15.421@93.88
Spinning thru 60' at least. With the traction control on it was worse, it switchedfrom tire to tire real stupid like.
 
NYC LSC said:
Yeah, that 60 is horendous lol

Just wanted to see if this was yet another 14.6 stock Mark VIII :D
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I wish, If I practiced my launch, I think I could break 15.
Do have some basic mods. The reason I posted was to see if that kind of 60' and still a 15.4 shows potential for high 14s. Plus the wheel mass, how much drag are they?
 
I heard this a while back:

1/2 lbtires are about a 1 lb of extra rolling weight
1 Lb rims end up being 4lbs
1 Lb of driveline weight is like adding 30 Lbs to your car!

I know these are rough but it'll give you an idea...
 
Stack said:
I heard this a while back:

1/2 lbtires are about a 1 lb of extra rolling weight
1 Lb rims end up being 4lbs
1 Lb of driveline weight is like adding 30 Lbs to your car!

I know these are rough but it'll give you an idea...
Click to expand...
At first that sounded high, but if the tire is 7lbs of it, and the rim is 8lbs of the xtra wieght. Thats 184lbs. Could be close. Thats a tenth at least. Any other good imput?
 
02LSE96LSC91SE84TC said:
I wish, If I practiced my launch, I think I could break 15.
Do have some basic mods. The reason I posted was to see if that kind of 60' and still a 15.4 shows potential for high 14s. Plus the wheel mass, how much drag are they?
Click to expand...

Generally, every tenth you shave off the 60' you shave 2 tenths off at the big end. So if you were to cut a 2.0 short time, you'd be lookin' at a 1 second reduction in your ET. I don't think you're gonna get that 2.0 short time with a stock converter and gears though.
 
NYC LSC said:
Generally, every tenth you shave off the 60' you shave 2 tenths off at the big end. So if you were to cut a 2.0 short time, you'd be lookin' at a 1 second reduction in your ET. I don't think you're gonna get that 2.0 short time with a stock converter and gears though.
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I agree, but a 2.2 is common for a stock but well tuned Mark. Yet many do only a 15.4. My 1st Mark for instance I hit a 2.3 yet a 15.5. So if I hit a 2.2 with this one, 14.8-14.9 should be possible. Thats what I'm trying to confirm to myself, that my mods, only being minor, are paying off. And my wheels, are part of the poor numbers.
 
Pulling this up from the past as I'm going to start to race it soon, well after my LSE breaks into the 14s. Throwing the stock wheels on may be the only thing I do before the first run and I'm looking for imput on what I can expect with just the wheel change. Gears and chip are next on the list, then shift kit and 255 fuel pump, pullies and better exhuast will probably follow, etc...
 
I've heard 1lb of wheel weight ends up being worth around 6lbs on the car. So 60*5 would be around 200, which should be worth about 3 tenths.

In your case I also blame the tire. A taller sidewall will hook better. If 15s would clear the brakes I would consider running them for that reason, since they won't I'm sticking to snowflakes.

My experiance was adding about 5lbs per wheel/tire on my ETC, and having it run the same 16.4 time. At the time I had shorter tires that effectively increased the final drive ratio from 3.71 to 4.22. The better gearing but higher weight seemed to cancel each other out. BTW both days the density altitude hung around 9000ft.
 
The 18's are slowing you down by about 2 tenths compared to the stock wheels. Why don't you throw the stock wheels/tires on there and see how it runs if you are so concerned about it.
 
This combo...
mini-100_1617.jpg

weighs in at 35lbs per wheel compared to 50lbs per wheel with the chrome 10 spokes and Nitto drag radials or Michelin Pilots.

Due to other mods during/after, it was difficult to ascertain a definite quantitative improvement in ET attributed solely to lighter rotating stock.

But believe in physics. It works everyday. ;)
 
do you just run those on the back, with 18's in the front too, or do you run 16's all around when you go to the track?
 
Oh BTW here are some figures on the rotational weight versus static weight conversion.






When converting rotational weight into static weight multiply times 8.

When converting back then just divide by 8.

Rotational weight affects a vehicle 8 times more then the same amount of weight just having to be lugged down the 1/4 mile (static weight).

Now this can never be perfectly accurate because it would have to take into account how far away from the point of rotation that the majority of the weight is, but it can be used as an accurate rule of thumb.

So, if we used 5 lbs difference per rim/tire as an example then it would be (5 x 4) x 8 = X

X = 160 pounds in this case.

Going off the old adage of 100 static lbs = .10 seconds in the 1/4, this would be a diff of .16 seconds with an average vehicle.

Now, the faster your vehicle is the less difference (proportionally) of ET that weight saving makes. This is why the 100=.10 rule works more accurately with 13-15 second cars, but not so much with 9-11 second cars.

Hope this helps anyone whom may be curious.
 
rocket5979 said:
When converting rotational weight into static weight multiply times 8.

When converting back then just divide by 8.

Rotational weight affects a vehicle 8 times more then the same amount of weight just having to be lugged down the 1/4 mile (static weight).

Now this can never be perfectly accurate because it would have to take into account how far away from the point of rotation that the majority of the weight is, but it can be used as an accurate rule of thumb.

...

Now, the faster your vehicle is the less difference (proportionally) of ET that weight saving makes. This is why the 100=.10 rule works more accurately with 13-15 second cars, but not so much with 9-11 second cars.
Click to expand...

In my case, 15 pounds x 2 = 30 pounds rotational weight
30 x 8 = 240 lbs static weight
240 / 100 = 0.24 seconds ET reduction

That would've been nice, but I doubt I actually achieved that. I suppose it might have been a tenth or so. But I figure my worn suspension is costing me in the launch so much it possibly negates the theoretical weight savings. :rolleyes:
 
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