S1 vs S2 Debate (SPLIT FROM INTERCOOLER THREAD) - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


Performance, Brainstorming & Tuning Talk about modifications, or anything else associated with performance enhancements. Have a new idea for performance/reliability? Post it here. No idea is stupid! (please use Detailing and Appearance for cosmetic ideas)

Reply
 
 
 
Thread Tools Search this Thread
Old 03-27-2008, 09:10 AM   #1
Junior Member
Posts like a Ricer Type-R
Thread Starter
 
Join Date: Aug 2002
Posts: 10
Thanks: 0
Thanked 0 Times in 0 Posts
willwren is on a distinguished road
Default S1 vs S2 Debate (SPLIT FROM INTERCOOLER THREAD)

Quote:
Originally Posted by GonneVille
Quote:
Originally Posted by willwren
Bill, what the H*** is your gearing? That thing shifts to 2nd at 40?! Crapsake, I'm not hitting the 1-2 till just over 50mph...
2.97. But you're forgetting the S1 is more of a low-end torquer than the S2.

I don't rev as high, I don't shift as high, and my hp and tq peaks are at lower rpm'* than yours.

In a nutshell, this is why I need the biggest jump to the 1/8 mile I can get to keep my lead by the 1/4 when racing S2'*.
willwren is offline   Reply With Quote
Old 03-27-2008, 11:05 AM   #2
Senior Member
Posts like a Turbo
 
Join Date: Aug 2005
Location: Grand Rapids,MI
Posts: 226
Thanks: 0
Thanked 0 Times in 0 Posts
Dirthead Racing is on a distinguished road
Default

Dirthead Racing is offline   Reply With Quote
Old 03-27-2008, 11:36 AM   #3
Junior Member
Posts like a Ricer Type-R
Thread Starter
 
Join Date: Aug 2002
Posts: 10
Thanks: 0
Thanked 0 Times in 0 Posts
willwren is on a distinguished road
Default

GM used to have both graphs on their drivetrain site, but I haven't seen them in awhile. I do recall very vividly how much flatter the Tq curve is on the S1 though. And for good reason.

The M62 rotors are much smaller in diameter. Same length, 3 lobes, 60 helical twist, but smaller in diameter and lighter. This means they spin up quicker. Anyone that'* driven both cars stock for stock or similar mods knows how quickly the S1 SNAPS into full boost. There'* a profound difference. This gets the S1 into boost and it'* tq peak at a much lower RPM:

92/93 = 260 @ 2600
94/95 = 275 @ 3200
96-03 = 280 @ 3600

Now imagine how this plays out at the track. The S1 will get off the line quicker, but then the S2 hits it'* tq peak, pulls, then gets into the hp peak at a higher rpm, making more out of each gear with nearly identical gearing. Holding a gear longer at higher rpm'* is a function of lighter rotating internals in the motor design (very much different than the S1). Another odd factor that most people don't know about is the 94/95 L67 actually has a SLIGHTLY larger throttle plate when compared to the Series 2 L67.

This is why the 94/95 L67'* will typically match or slightly edge the S2 L67 in stock form (particularly the heavier 2000'*). Into the boost and tq quicker but with almost the same torque peak (only 5ft/lbs off between the two, but the S1 is into the peak 400 rpm'* sooner), and still producing 225hp in stock form. Only a 15hp difference, but they got the jump off the line due to the tq. Nearly equal on the quarter, S1 advantage at the 1/8, and the race would be owned by the S2 if it went to the half mile. Trap speeds would be killer too.

The long and short of it is the two motors were designed very differently for two different effects. The differences are PRIMARILY the mass of the rotating internals and the mass of the rotors in the SC. They both produce the same CFM at a given RPM, but only because the 62 is spinning faster to do it. But the 62 requires less hp to drive the smaller 'charger.

The M62 robs 8hp at 4000 rpm'* to produce 10psi, and about 5hp to produce 5psi at 4000 rpm'*.

The M90 takes an even 10hp (2 more) to produce 10psi at 4000 rpm'*, and about 6hp (1 more) to produce 5psi at 4000 rpm'*.

Taking it out farther, the M90 requires 42hp to spin 12000 rpm'* at 10psi, where the M62 only requires 35 to do the same.

What'* the difference? Both were intended for our displacement. They just overlap for the application. The M62 was designed for 2.0-4.0 liter displacement engines, where the M90 was designed for 3.0-5.7 liters. Both work, you just pulley them differently.

The M62 makes it'* boost without using as much hp to drive the supercharger as the M90, but at a cost. It'* smaller, spins faster, and produces more heat in doing so, causing efficiency to drop off at the top end a little quicker.

I could go on for another hour here, but I think I'd lose the audience. These are just some explanations for why the Series 1 performs so well at the bottom end, and the Series 2 is a little better from mid-trap.
willwren is offline   Reply With Quote
Old 03-27-2008, 12:32 PM   #4
Senior Member
Posts like a Northstar
 
Join Date: Oct 2004
Location: Purgatory
Posts: 533
Thanks: 0
Thanked 0 Times in 0 Posts
Greyhare is on a distinguished road
Default

Quote:
Originally Posted by Dirthead Racing
last time I checked rockers shift powerband up with higher lifts.
Please explain.
Greyhare is offline   Reply With Quote
Old 03-27-2008, 12:41 PM   #5
Junior Member
Posts like a Ricer Type-R
Thread Starter
 
Join Date: Aug 2002
Posts: 10
Thanks: 0
Thanked 0 Times in 0 Posts
willwren is on a distinguished road
Default

Last time I checked, increasing rocker ratio shifts the peak up, but not the rpm delivered. It takes a cam (in general) to shift the powerband itself.

Here'* a different way of looking at my sermon a couple posts up:

Name:  L67comparison.jpg
Views: 0
Size:  107.6 KB
willwren is offline   Reply With Quote
Old 03-27-2008, 12:50 PM   #6
Senior Member
Certified Car Nut
 
Join Date: Mar 2003
Posts: 12,432
Thanks: 0
Thanked 0 Times in 0 Posts
J Wikoff is on a distinguished road
Default

Aren't we getting off topic?
J Wikoff is offline   Reply With Quote
Old 03-27-2008, 12:55 PM   #7
Senior Member
Posts like a Turbo
 
Join Date: Aug 2005
Location: Grand Rapids,MI
Posts: 226
Thanks: 0
Thanked 0 Times in 0 Posts
Dirthead Racing is on a distinguished road
Default

Dirthead Racing is offline   Reply With Quote
Old 03-27-2008, 12:58 PM   #8
Senior Member
Posts like a Turbo
 
Join Date: Aug 2005
Location: Grand Rapids,MI
Posts: 226
Thanks: 0
Thanked 0 Times in 0 Posts
Dirthead Racing is on a distinguished road
Default

Dirthead Racing is offline   Reply With Quote
Old 03-27-2008, 01:07 PM   #9
Senior Member
Certified Car Nut
 
Join Date: Mar 2003
Posts: 12,432
Thanks: 0
Thanked 0 Times in 0 Posts
J Wikoff is on a distinguished road
Default

Why is this becoming a S1 S2 discussion?

S1 stock dynos are gonna be damn near impossible to find, so we gotta go by vehicle performance.

Bill didn't say the SC'* produce the same PSI at 12000 rpm.
J Wikoff is offline   Reply With Quote
Old 03-27-2008, 02:34 PM   #10
Senior Member
Posts like a Turbo
 
Join Date: Aug 2005
Location: Grand Rapids,MI
Posts: 226
Thanks: 0
Thanked 0 Times in 0 Posts
Dirthead Racing is on a distinguished road
Default

Dirthead Racing is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
The Debate about Overfilling a transmission? Which is true? h1081dan General GM Chat 53 09-14-2005 05:11 PM
need support for me V.S. parents "debate" corvettecrazy 1992-1999 34 02-25-2005 11:34 AM
The Great Bonneville Debate Jim W 1987-1991 20 03-17-2003 03:17 AM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 07:54 AM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.