Pelican Parts
Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   Pelican Parts Forums > Porsche Forums > Porsche 911 Technical Forum


Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Registered User
 
Bill Douglas's Avatar
 
Join Date: Jun 2000
Location: bottom left corner of the world
Posts: 12,708
Big performance increase 911SC

I swapped out the heavy 17" Carrera Cup fakes for the factory fitted 16" wheels.

Wow, the car feels so much faster, responsive, snappier, the list goes on. I loved the look of the 17" wheels with big rubber, but all of that extra rotating mass was not good for the car.

911SC Sport with 930/10, cams and SSIs.
__________________
see www.lyallbaybeach.co.nz
Old 12-11-2018, 08:26 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #1 (permalink)
Banned but not out, yet..
 
RSBob's Avatar
 
Join Date: Jan 2003
Location: "Apple Maggot Quarantine Area', WA.
Posts: 5,595
Garage
That is so cool that you got that kind of gain.

Makes me wonder about my Linea Corsa 17” 7s and 9s.

Bill did you reduce the tire size as well or just the wheels?
__________________
Made of matter, but not that much
Old 12-11-2018, 09:02 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #2 (permalink)
Registered User
 
Join Date: Oct 2001
Location: Hotel California
Posts: 645
Garage
… having to install spacers to kick out those wide 17 wheels that the Carrera and 930 suspension design did not need to do to such a large extent I suppose that makes sense. Boy if you can feel the difference on your 930 motor then a non aspirated 3.0 SC stock with 17's /wide rubber must really be a slow boat in comparison. What particular stability and control issues has this move corrected ? also in what range does the 'much faster' factor come into play …. taking off or acceleration ?
__________________
antares
fatnwide - uncle dave

79 All steel wide body Targa / euro 915 oil cooled LSD / SSI's / RUF 8 & 10's / light flywheel plus lots other silly mods n upgrades
Old 12-11-2018, 09:13 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #3 (permalink)
Registered User
 
aircooled pegasus's Avatar
 
Join Date: Apr 2002
Location: Los Angeles
Posts: 909
Garage
The SC/Carrera looks so proper with 16s.

Those fake Carrera Cups are quite heavy also.
Old 12-11-2018, 09:44 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #4 (permalink)
Registered User
 
madcorgi's Avatar
 
Join Date: Nov 2005
Location: Seattle, WA
Posts: 13,740
Garage
I'm a fan of running stock-sized tires on my car (1985 Carrera--205 and 225s), though I have swapped out the original 6&7 x 16s for aftermarket Fuchs 7&8x16s with the stock rubber. Just because I like the looks . . .
__________________
IAMPARTOFTHERESISTANCE

https://forums.pelicanparts.com/porsche-911-technical-forum/1022378-yes-its-another-white-911-build.html
Old 12-11-2018, 10:31 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #5 (permalink)
Registered User
 
Bill Douglas's Avatar
 
Join Date: Jun 2000
Location: bottom left corner of the world
Posts: 12,708
Quote:
Originally Posted by RSBob View Post
Bill did you reduce the tire size as well or just the wheels?
The circumference is the same but the back ones went from being 245s down to the stock 225 in width. I just think the fake Carrera Cup wheels were SO heavy.

Quote:
Originally Posted by antares View Post
what range does the 'much faster' factor come into play …. taking off or acceleration ?
It might be placebo effect, but the car feels more lively, more responsive. More acceleration I would say. Haha, easier to park too instead of muscling the steering wheel around.
__________________
see www.lyallbaybeach.co.nz
Old 12-11-2018, 10:57 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #6 (permalink)
Registered User
 
Mike964_61's Avatar
 
Join Date: Apr 2018
Location: South Tampa
Posts: 280
Garage
You should have weighed the wheels so you would have an actual number. I would have like to known the difference.
Old 12-12-2018, 03:47 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #7 (permalink)
Behind the Sun
 
Join Date: Jul 2014
Location: Tejas
Posts: 122
Scrub Radius. The answer. No black magic, butt dyno or witchery
Old 12-12-2018, 03:59 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #8 (permalink)
Registered User
 
T77911S's Avatar
 
Join Date: Oct 2006
Location: MYR S.C.
Posts: 11,618
my 930 has 18's. I sometimes wish it had the 16's for performance but the 18's look awesome
__________________
86 930 42kmiles [__] RUNNING:[__] NOT RUNNING: ____77 911S widebody: SOLD
88 BMW 325is 200K+ SOLD
05 BMW 330CI 130K:: [__] RUNNING: [__] NOT RUNNING:
08 VOLVO V70 190K:: [__] RUNNING: [__] NOT RUNNING:
90 B2200[__] RUNNING:[] NOT RUNNING:__2000 MER E320 WAGON [] WRECKED:[]RUNNING:
Old 12-12-2018, 04:07 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #9 (permalink)
Moderator
 
Bill Verburg's Avatar
 
Join Date: Dec 2000
Posts: 23,338
Garage
Just changing from 17 to 16 is no guarantee that you will experience and improvements

It's all about tire OD and the weight of the rotating assembly, tire OD is potentially the most significant and tire weight is more significant than wheel weight which is more significant than rotor weight which is more significant than hub weight.

Judicious choices can make a big difference

here's on example using only 1 tie line, Bridgestone RE71, 16s vs 17s. No change in scrub radius

Here the 17s are going to be ~1.7lb-ft better, for acceleration ~.6 lb-ft worse for braking and also provide better grip in the corners
__________________
Bill Verburg
'76 Carrera 3.6RS(nee C3/hotrod), '95 993RS/CS(clone)
| Pelican Home |Rennlist Wheels |Rennlist Brakes |
Old 12-12-2018, 04:32 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #10 (permalink)
Get off my lawn!
 
GH85Carrera's Avatar
 
Join Date: Nov 2007
Location: Oklahoma
Posts: 52,986
Garage
It is strange you can feel in in the seat of your pants.

My 85 came with 15 inch Fuchs, 7s and 8s. It is pretty much impossible to find good performance summer tires that can be used on the highway for long road trips in the 15 inch size. I finally gave up and bought some Euromiester wheels. Pilot Sport tires have orders of magnitude more grip for cornering, and work great in the rain. I did not notice any set of the pants difference in acceleration.

For sure the 15s are lighter that the 17s I have now, but I sure like the driving feel of the 17s.
__________________
Glen
42 Year member of the Porsche Club of America
1985 911 Carrera; 2017 Macan
1986 El Camino with Fuel Injected 350 Crate Engine
My Motto: I will never be too old to have a happy childhood!
Old 12-12-2018, 06:03 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #11 (permalink)
Moderator
 
Bill Verburg's Avatar
 
Join Date: Dec 2000
Posts: 23,338
Garage
Quote:
Originally Posted by GH85Carrera View Post
It is strange you can feel in in the seat of your pants.

My 85 came with 15 inch Fuchs, 7s and 8s. It is pretty much impossible to find good performance summer tires that can be used on the highway for long road trips in the 15 inch size. I finally gave up and bought some Euromiester wheels. Pilot Sport tires have orders of magnitude more grip for cornering, and work great in the rain. I did not notice any set of the pants difference in acceleration.

For sure the 15s are lighter that the 17s I have now, but I sure like the driving feel of the 17s.
W/o knowing details of you specific case I can only guess, but here goes
stock 7 & 8 x15 Fuchs w/ 185/70 & 215/60 tires changed to Michelin PS2(no data on PS) on Euromeister 7 & 8 x17

There would be only a small ~4.6 lb-ft difference, every one is different but that's likely to be not very noticable. But on others changes i've seen far larger differences up to ~45lb-ft


__________________
Bill Verburg
'76 Carrera 3.6RS(nee C3/hotrod), '95 993RS/CS(clone)
| Pelican Home |Rennlist Wheels |Rennlist Brakes |
Old 12-12-2018, 06:31 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #12 (permalink)
 
Turbo Powered Snow Blower
 
Join Date: Mar 2016
Location: Rocklin, CA .... Galveston, TX
Posts: 3,214
Garage
Based on the title I was sure you added a turbo.
__________________
Derrick
Old 12-12-2018, 07:38 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #13 (permalink)
Registered User
 
Join Date: Jul 2001
Location: Portland Oregon
Posts: 6,992
Quote:
Originally Posted by 2.7RS View Post
Scrub Radius. The answer. No black magic, butt dyno or witchery
Nossir.

Moment of inertia (and weight)!

This is what Bill felt when he switched from his heavy 17" wheels to the original 16" ones.
__________________
Steve Weiner
Rennsport Systems
Portland Oregon
(503) 244-0990
porsche@rennsportsystems.com
www.rennsportsystems.com
Old 12-12-2018, 07:41 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #14 (permalink)
Registered User
 
Join Date: Oct 2016
Location: PNW
Posts: 517
Quote:
Originally Posted by antares View Post
having to install spacers to kick out those wide 17 wheels that the Carrera and 930 suspension design did not need to do to such a large extent I suppose that makes sense. Boy if you can feel the difference on your 930 motor then a non aspirated 3.0 SC stock with 17's /wide rubber must really be a slow boat in comparison. What particular stability and control issues has this move corrected ? also in what range does the 'much faster' factor come into play . taking off or acceleration ?
He has a non aspirated stock 3.0. I think the engine code is confusing you 930/10 simply denotes a ROW 911SC engine.
__________________
_______________________________
1982 911 SC 230,000mi and counting
Old 12-12-2018, 08:02 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #15 (permalink)
Registered User
 
Join Date: Apr 2006
Posts: 811
Quote:
Originally Posted by QueWhy View Post
He has a non aspirated stock 3.0. I think the engine code is confusing you 930/10 simply denotes a ROW 911SC engine.
This
__________________
Ass-engine Nazi slot car -- PJ O'Rourke
Old 12-12-2018, 08:31 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #16 (permalink)
Registered User
 
john walker's workshop's Avatar
 
Join Date: Mar 2001
Location: Marysville Wa.
Posts: 17,661
My77 930 felt more nimble when I lost the Ruf 17X9/10s and put the fuchs 16X7/8s back on. Lot less railroading too.
__________________
8009 103rd pl ne Marysville Wa 98270
206 637 4071
Old 12-12-2018, 08:45 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #17 (permalink)
Registered User
 
GaryR's Avatar
 
Join Date: Mar 2005
Location: Valencia, Spain
Posts: 4,597
Garage
Send a message via ICQ to GaryR
Read the OP and then scanned down to see (I KNEW he would respond!) Bill V's input on this. He was of great help when many of us switched our SC race cars from 18" (very light) CCW wheels with 275/35 Hoosiers to 15" Jongbloeds with 275/35 15's.. We did the same with our E class 3.2 cars, the gearing is changed across the board, similar to running a 7:31 R&P. Acceleration out of corners was improved and it changed our cars from virtual 4 speeds (on all tracks I frequented) into 5 speeds..There was a substantial running diameter difference in these two tires, doubt if going 17" to 16" on a similar tire would have the same or even similar effect?
__________________
Gary R.

Last edited by GaryR; 12-12-2018 at 08:57 AM..
Old 12-12-2018, 08:54 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #18 (permalink)
Registered User
 
T77911S's Avatar
 
Join Date: Oct 2006
Location: MYR S.C.
Posts: 11,618
my brothers 930 still have 16's, we have not raced much but I think he is quicker.

also, my car sits much higher than his, especially in the rear.
I have 285-35-18 in the rear.
__________________
86 930 42kmiles [__] RUNNING:[__] NOT RUNNING: ____77 911S widebody: SOLD
88 BMW 325is 200K+ SOLD
05 BMW 330CI 130K:: [__] RUNNING: [__] NOT RUNNING:
08 VOLVO V70 190K:: [__] RUNNING: [__] NOT RUNNING:
90 B2200[__] RUNNING:[] NOT RUNNING:__2000 MER E320 WAGON [] WRECKED:[]RUNNING:
Old 12-12-2018, 08:57 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #19 (permalink)
Moderator
 
Bill Verburg's Avatar
 
Join Date: Dec 2000
Posts: 23,338
Garage
Quote:
Originally Posted by T77911S View Post
my brothers 930 still have 16's, we have not raced much but I think he is quicker.

also, my car sits much higher than his, especially in the rear.
I have 285-35-18 in the rear.
Hopefully that is a 285/40 x18, @24.8" OD that is a sweat rear tire only ~.1" taller than a 245/45 x16 and w/ roughly equal inertial cost, hopefully w/ 245/35 or 255/35 fronts for matching balance.
__________________
Bill Verburg
'76 Carrera 3.6RS(nee C3/hotrod), '95 993RS/CS(clone)
| Pelican Home |Rennlist Wheels |Rennlist Brakes |
Old 12-12-2018, 09:11 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #20 (permalink)
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 11:40 PM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page
 

DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.