quickWS6

What kind of improcement in E.T. and trap speed should a 15x3.5 skinny give over a 17x9" WS6 wheel with 275/40/17s on them? A good bit I would think. Thanks in advance.

zturbo

Not sure on the exact et diff but think of it this way..

17x9 with 275's weigh 47-50 lbs.. each

15x3.5 with tires around 20-24 depending.

Steven

bigSS

The faster you go, the more they help. <img src="gr_stretch.gif" border="0">

I think the norm for most cars is 1 tenth, a little more for modified (H/C) vehicles.

Ebbsnflows

iTrader: (15)

I added skinnies and an LS6 intake at the same time and saw .2 on my H/C combo. It's hard to say which gave me the most...but my bet is the skinnies gave me the majority.

Trevor @ Texas Speed & Perf.

iTrader: (3)

I can't believe nobody has done some back-to-back runs w/ 17's and then skinnies! SO many people are running skinnies. I guess I'll have to do it when I get them. <img src="gr_images/icons/cool.gif" border="0">

bigSS

Same here. <img src="gr_stretch.gif" border="0">

McRat

On a 12 sec car, about 0.10-0.15.

By switch to Skinnies and ET Streets, with the same 60' times my car picked up 0.25.

So let's say 0.12. That's equivalent to 12hp. Going by the "McRat Threshold of Pain" which equals $40/hp on LS1's, they come in at $350 with tires (VW Tires) so that's ~$30/hp. A good value relatively speaking.

MysticZ28

[quote]Originally posted by McRat:
<strong>On a 12 sec car, about 0.10-0.15.

By switch to Skinnies and ET Streets, with the same 60' times my car picked up 0.25.

So let's say 0.12. That's equivalent to 12hp. Going by the "McRat Threshold of Pain" which equals $40/hp on LS1's, they come in at $350 with tires (VW Tires) so that's ~$30/hp. A good value relatively speaking.</strong><hr></blockquote>

I'm confused ... if you switched to skinnies and ET Streets at the same time, but your 60' stayed the same (I'm assuming to the 60' prior to the ET Streets). Wouldn't that make the ET Streets essentailly a non-factor and the entire .25 gain would be attributed to the skinnies??

[ December 15, 2001: Message edited by: MysticZ28 ]</p>

McRat

No, there is a big weight savings on the ET Streets Convo combo as well. Believe it or not, the Convo Pro/VW steel belted tires up front weigh about the same as the ConvoPro ET streets out back.

It is possible I gained more from the skinnies than the Streets, but to be honest, I'm not sure.

Why didn't my 60's improve? They did. But I compared slips with the same 60's.

McRat

look here for weight of wheels and tires:

http://www.ls1.com/ls1forum/Forum32/HTML/000476.html

MysticZ28

My bad ... I assumed the ET Streets was just a tire change. If I undertand you went to a full 15" set up all round and all at the same time.

I'm considering the Convo Pro/165x15 set up in front. My understanding is that the Convo Pro 15x4 with a 1.75 off set will need no grinding and no spacer up front?

On the back did that require grinding and spacers?

Thanks, Mike

Terry Burger

iTrader: (4)

I think its .05 ths for most cars.

McRat

[quote]Originally posted by MysticZ28:
<strong>My bad ... I assumed the ET Streets was just a tire change. If I undertand you went to a full 15" set up all round and all at the same time.

I'm considering the Convo Pro/165x15 set up in front. My understanding is that the Convo Pro 15x4 with a 1.75 off set will need no grinding and no spacer up front?

On the back did that require grinding and spacers?

Thanks, Mike</strong><hr></blockquote>

No grinding or spacers needed. You do need different lug nuts though.

On an SS, you will save about 40lbs off the front. But since it is rotating mass, the gain is more than the weight would indicate.

If I had to do it again, I probably would have tried to find lighter front tires. But still, it's been one the better mod's I've done. It's like free HP without wrecking the car.

Terry Burger

iTrader: (4)

[quote]
On an SS, you will save about 40lbs off the front. But since it is rotating mass, the gain is more than the weight would indicate.
<hr></blockquote>

Pat, shame on you! The engine isn't accelerating the front wheels (like it does the rear), so front wheel weight is not included in what we consider "rotating mass".

40#s is a good amount of weight savings though. I ran a set of skinnies on my car for a week or two, I think it was worth ~.05th at LACR, but it made the car look like a race car. It is so much stealthier with the stock wheels on the front. My borrowed set saved around 30# over the stock 2001 Z28 rims.

Black LS1 T/A

Somebody tell me if I mis-percieve:

When I picked up my ET Streets Tire, they felt as if they weighed less than my stock tire.

MysticZ28

Thanks, McRat. As soon as the budget can absorb it, I'm going to go with the 15x4 Convo Pros up front. Then after I burn up my latest set of 16" QTPs, I'll probably go ahead and step up to some 15" out back since I don't have to grind.

We're working on putting together a GM event up at Fomaso in April. If it works out hope to see you there ... maybe we can give each other a run <img src="gr_images/icons/wink.gif" border="0">

McRat

[quote]Originally posted by Terry Burger:
<strong>

Pat, shame on you! The engine isn't accelerating the front wheels (like it does the rear), so front wheel weight is not included in what we consider "rotating mass".

....</strong><hr></blockquote>

Think about it Terry. You must not only carry the weight of the front tires all the way down the track, but you must accelerate them rotationally from 0mph to 110 in 12 sec (for me). It certainly DOES take alot of power to get 90lbs of SS wheels to accelerate to 110mph. Shave it down to 50, and it's much easier.

McRat

[quote]Originally posted by High Tenor:
<strong>Somebody tell me if I mis-percieve:

When I picked up my ET Streets Tire, they felt as if they weighed less than my stock tire.</strong><hr></blockquote>
They weigh MUCH less than 275/40-17 steel radials.
About 10lbs less each. An ET Street with ConvoPro weighs about the same as JUST AN EAGLE F1 tire alone <img src="gr_eek2.gif" border="0">

Nicest thing? They are much easier carry back to garage <img src="gr_images/icons/wink.gif" border="0">

McRat

[quote]Originally posted by MysticZ28:
<strong>...

We're working on putting together a GM event up at Fomaso in April. If it works out hope to see you there ... maybe we can give each other a run <img src="gr_images/icons/wink.gif" border="0"> </strong><hr></blockquote>

I'd like that! As soon as you firm up a date for Famoso, email me, and I'll try to get the LS1 Western guys to head up also!

I'm going to try to make it up to Sacramento in the next month or two, I'll drop you line and see if you can run me on your home turf.

Colonel

"The engine isn't accelerating the front wheels (like it does the rear), so front wheel weight is not included in what we consider "rotating mass"."

Surely you're kidding? If the engine isn't what's accelerating the front wheels I don't know what is. I know, you WERE kidding, but I had to make sure. <img src="gr_stretch.gif" border="0">