S1 vs S2 Debate (SPLIT FROM INTERCOOLER THREAD)
 

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's 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's.

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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's driven both cars stock for stock or similar mods knows how quickly the S1 SNAPS into full boost. There's a profound difference. This gets the S1 into boost and it's 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's 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's 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's will typically match or slightly edge the S2 L67 in stock form (particularly the heavier 2000's). 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's 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's to produce 10psi, and about 5hp to produce 5psi at 4000 rpm's.

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

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

What's 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's boost without using as much hp to drive the supercharger as the M90, but at a cost. It's 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.

Please explain.

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

Attachment 33669

Aren't we getting off topic?

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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's produce the same PSI at 12000 rpm.

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This'll probably get split out, but I figured you guys (including dirthead) would appreciate a little demonstration of how the M62 can creat boost.

Cruising at 65, having a little fun. Audio selected to PROVE time-scale. Careful you don't get whiplash watching the needle.

https://i14.photobucket.com/albums/a...h_MOV01162.jpg
(Check out that oil pressure :D )
EDIT:

On a side note, I've been noticing with the IC running, my coolant temps stay a bit lower (noticable, but not significant), and my fuel mileage has improved, especially around town where it was really starting to suffer from the mods.

How can that be Bill :?:

Mine makes boost proportional to the rpm of the engine and my engine doesn't spin up that fast. :?

Must be the special programming. ;)

Paul, it's simple gear ratio and rotating mass. My ratio is more extreme than yours (same crank pulley, far smaller SC pulley) and my SC spins up quicker due to it's smaller mass on the rotors.

My SC has ALWAYS spooled into boost quicker than yours, going all the way back to WCBF 04, when we were both mostly stock. That's what I was trying to explain to Dirthead. And it costs me less HP than it does you to drive the SC as well.

Well yes I under stand that but honestly I have always thought your gauge sensitivity was too high. :P

Think about it. The SC rotors will not spin up any faster than your engine since it's direct coupled....unlike a turbo.
Boost builds linearly with rotor rpm. 8)

When you stab your throttle you are maybe seeing 3000 rpm and your boost gauge is reading 10 psi like right now :twisted:
You have a loose torque converter. ;)

So at 5000 rpm you would be at about 15 psi..............hey wait a minute that about right isn't it. :lol:

I rest your case..

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Paul, my boost gauge, as well as John's (the two you're most familiar with) have always SNAPPED into boost. Even Pdad was stunned in 2004. I have no loose TC. Trust me, I'd know. There are two important notes to make here:

1. Mine snaps into boost more quickly than any other Series 1 partially due to the extra idler. I gained much better power through the midrange. I was getting belt slip during accelleration (not at WOT, but on the way there). I get much better boost response during accelleration now, simply because of the improved belt wrap. This is true with both Gates and GoodYear belts. Please note that ALL Series 1's have belt slip with a 2.2" pulley and a brand new tensioner and either brand of belt. I can link you to the topic if you like. The belt path is very different on the S2, and it was re-engineered for this reason. I gaurantee it.

2. Let's also remember that my intercooler design is quite different than the commercial offerings. I RETAIN my boost/vacuum source inside the manifold, and it doesn't have to go through the core of the intercooler. It bypases it altogether. In addition, my core has greater flow area (less restriction) as it's wider and a little longer than a S2, but not as thick. I also have 'overflow' protection at each end so that if the boost builds quickly or is affected by the core, it will simply bypass the core altogether to keep pressures in line.


Dirthead, if you think this is some kind of tag-team scam, you're a fool. Too many people here know and drive my car personally several times a year, and all of them are familiar with other Series 1's on the West Coast. God knows I have a reputation for lying and faking shit on my cars. That whole thing last year at Woodburn dragstrip where I was ripping 1.9 sixty-foots side-by-side with a 12-second GTP? Faked, obviously. PDXGTP is in on the scam also. Yes, my car freaked him out as well. Why? He wasn't familiar with how different of a beast the S1 really is. Those unfamiliar with them simply classify them in their minds as 'inferior and the older type' when in reality, they just shine in a different way. The two types were designed for two very different reasons.

This isn't some kind of scam. It's an answer to the question you asked about why the S1 has stronger bottom end grunt than the S2 (and falls on it's face at the top end). I suggest you go drive one for yourself.

As I stated before, I used to have the curves, as we all did 'back in the day' here, but they are no longer posted on GM's drivetrain site. Rather than calling this a tag-team scam, maybe you should spend the time to find the curves for yourself.

Have you got proof to show otherwise?

Dirthead.... This wasn't even a series I vs Series II debate till you came along and made it that....

And at the same time... The HP peak of the Series I 91.5-93 L67 is lower than the rest of the years... And the PCM will force a shift before the engine ever sees red line.... Stock for stock a series I 92-93 will force a shift at 5200 Rpms and even that is with a 5600 red line... Even with Bills Jet Chip the shifts are only a couple hundred RPM's higher...

When you can shift Bone stock at 5900-6000 and or 5200 on the 92-93 L67 there is going to be a decent difference in shift points... Forcing a series I to shift at 6000 on a stock Cam will push the motor way out of its power band... Even with the Rockers by the time he shifts he is out of his power band... The series I does not have Legs like the 3800 II....


This is not a debate.... The two engines are very different in the way they produce power

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Have you ever noticed that it's the MANNER in which you ask the questions that the problem comes from?

What you intend and what we percieve are two different things. If you'd like to discuss this offline, feel free to PM me.

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Do you have anything worthwhile to add to this thread?

I know exactly how to interpret dynographs, thank you very much.

Perhaps you didn't read. "S1 dynos are going to be damn near impossible to find, so we have to go by vehicle performance."

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It's not a cop out at all. One car out performing a similar weighted and geared car in the 1/8th is a pretty good indicator of more low end grunt. Dyno charts aren't the only things that speak, you know.

Dirthead, I pulled that 1.9 sixty with FAR fewer mods than you, BadSSEi or Rogue. If you want to skew the samples to make the data go in your favor, pick another topic to do it in.

here is a STOCK GTP that Intense/DynoTune MS strapped on less than a few weeks ago


http://24.26.129.28:50001/Dyno%20Gra...20Baseline.jpg

and the thread that everyone can read...... stock as stock can be
http://www.3800pro.com/forum/round-t...ke-wheels.html

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Dirthead, the only power adders on my car when I pulled that last year were a ported SC, mildly ported heads, and rockers. I launched with the cutout closed for two of my 1.9's.

All the rest are tuning or gauges. The S1 is far more difficult to tune than the S2. That's why my list is long.

I figured you would have the experience to see a mod list and actually determine which mods add power, and which mods are used to tune it afterwards.

I'm really sick of arguing stupid crap in this topic, which had to be split from my other topic due to your off-topic posting. I suggest you drop the issue or post a topic of your own, or even better yet, do the research on your own. Nobody wants to argue with a brick wall, and this should be a DISCUSSION, not an argument or debate. Your MANNER of posting invites argument.

I'm not familiar, is a GTP geared the same as a Bonneville? Just want to make sure, if we ever find a S1 dyno, that we compare apples to apples. If you can even manage to record a run far enough below 3k rpm to capture its peak reliably for either motor.

Yes a GTP is geared the same as a bonneville.

Debates such as this lead to nowhere but more negativity. I have asked that this stop and the parties have agreed. It is wonderful to have a difference of opinion - that is how we learn from each other. But sometimes it is better to agree to disagree, or at least take a break, think about the situation, and then re-address it at another time.

Thank you all for your cooperation.
Tracy