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3.8 vs 3.6

 
Old 11-24-2018, 11:45 AM
  #31  
Bill Verburg
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First your '97 comapares well w/ another 3.6 vram i have data for, the torque boost compared to a 3.6 non vram is obvious, and peak is a bit better than my 3.6RS


Here's what yours looks like compared to my 3.8RS w/ g50/30, the obvious thing is the missing 500rpm

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Old 11-25-2018, 06:38 PM
  #32  
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Got ShiftRPM on iPhone - entered my data, and this is the output - interesting -Thanks Pete
Now need to try and figure out what I am looking at. As for a Varioram engine it appears I am in the higher RPM too much. But on some tracks it works well - asTurn 7 Road Atlanta and Oak Tree VIR. Running the S's at RA in 4th and works well.
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Old 11-25-2018, 06:47 PM
  #33  
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Hmmm - try this -
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Old 11-25-2018, 08:07 PM
  #34  
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Great thread. Anybody have any thoughts on a 964 having a 996 Cup Clutch? I raced my RSA for years and putting it back to street duty. Between the light weight flywheel and the 996 Cup clutch it's just about impossible to have a smooth take off or have the car stall when I come to a stop. I'm assuming that a clutch swap out to stock (or is there a better alternative?) and going to the heavier flywheel are in order. I feel like I'm highjacking the thread but it seems many that are chiming in my have some thoughts.
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Old 11-26-2018, 11:58 AM
  #35  
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Originally Posted by Gus View Post
Got ShiftRPM on iPhone - entered my data, and this is the output - interesting -Thanks Pete
Now need to try and figure out what I am looking at. As for a Varioram engine it appears I am in the higher RPM too much. But on some tracks it works well - asTurn 7 Road Atlanta and Oak Tree VIR. Running the S's at RA in 4th and works well.
First, your motor is quite strong compared to the ones I see. This could be because it is or because of different dynos. All the ones I've posted here were done on a Dyna Pak.

The main unusual feature is the big step from 4 to 5. This is often done to provide a more reasonable cruise rpm

Here's is what I get for the base configuration of your trans, I used a 255/40 x17 tire w/ a 24.1" loaded height based on 836 revs/mi


If you can provide the rear tire details, make & size(Hoosier R7 255/40 x17 ?) and the car aero features, 964 base or RSA or?? I'll run the #s for you and post later

I don't know if you realized it or not but the charts you did are rear wheel torque, this is no the same as the thrust charts I posted, Also aero effects reshape the thrust curves and need to be included.
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Old 11-26-2018, 12:40 PM
  #36  
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Bill - thanks for the feed back - The tires I run on the rear are Nitto NT01's 275/30 x18 25.5 diameter. I will include 2 pictures of car to show front spoiler with winglets (?) and then an over all pic of the car so you can see rear wing. I noticed a 2-4 MPH drop on top speed on the Road Atlanta back straight after I added the rear spoiler, then a little additional drop with addition of the winglets on the front. The traid off is acceptable as the car feels much stabler at top speed as I use to have a very light feeling front at high speeds - So I can live with the extra drag. The top gear was held at the 0.92 ration as I did want to have a little savings at cruise speed on the hwy. Right now I am 70 at 3000 RPM in 5th.
As to the dyno numbers realize that all are a little different and numbers change on any given day. But I have used the same dyno - DynoResearch -for the last 15 years - A few quick samples are:
2003 - Stock set up - 241 hp with 220 Torque
2008 - intake and stock exhaust mods - 258 HP with 234 Torque
2011 - major mods all external, new ECU (stand alone) - 275 HP with 256 Torque
2015 - Varioram added new direct coil packs/ no distrib - 286 HP with 265 Torque
2018 - Motec M84, coil n plug, major rebuild (P & C) 993 valves, dif exhaust - 294 HP with 270 Torque ( Not as much as I thought which started this post)
So the readings seem to follow the improvements from the time I got the car to the current status.
What is not reflected is the reduction in weight of the car over the same period of time as i have pulled some 800lbs off the car.
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Old 11-26-2018, 03:48 PM
  #37  
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NT-01275/35 x18 is the same tire I use, the loaded rolling diameter effectively is 24.8"

By raised the Cd of an RSA +.01 to apx your drag

Yours is the yellow plot, the other 2 are a stock 964RSA w/ g50/03 and a stock 993 nvr w/ g50/30


The thing that jumps out at me is that you probably could us a few more revs, the tails never quite meet the next curve on yours
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Old 11-26-2018, 04:44 PM
  #38  
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Bill - thanks for putting graphs together. Greatly appreciate you taking time to do. Iím running the stock 964 cams - so getting more RPM isnít there. Guess switching to a more aggressive cam is the only way to get there. Not sure what cam will work with the stock 993 piston and 993 valves to get max HP at around 7000 - 7200. Will have to start looking - want something that will still be streetable though.

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Old 11-26-2018, 04:58 PM
  #39  
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Bill, thanks for making those charts with my gears. I'm in need of some topend which will be addressed in the form of heads/cams this winter.

Gus, you're motor is making some great torque to the wheels starting at 3,000rpm. Nice. Did you use 964 or 993 cylinder heads. I'm curious what size intake/exh valves? Love the livery btw. Very cool.
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Old 11-26-2018, 05:14 PM
  #40  
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Sanders, I used the 964 cylinder heads, but machined to match the 993 cylinders with gaskets. I rebuilt with 993 pistons and cylinders, Carrolla Rods, and stronger valve springs, 993 valves which are just a little larger. Cleaned/ polished intake ports but minor removal. Running stock 964 cams. Already had light weight fly and turbo clutch. Running a Motec M84 ECU with cool on plugs - custom exhaust.
Guess I should changed cams
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Old 11-26-2018, 05:19 PM
  #41  
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Originally Posted by Gus View Post
Bill - thanks for putting graphs together. Greatly appreciate you taking time to do. Iím running the stock 964 cams - so getting more RPM isnít there. Guess switching to a more aggressive cam is the only way to get there. Not sure what cam will work with the stock 993 piston and 993 valves to get max HP at around 7000 - 7200. Will have to start looking - want something that will still be streetable though.

Theses work great!ELGIN SUPER C-2
Seat timing 280 270
@.05lift 242 230

lift 0.475 .455

lobe centers 113 113
lift @overlap w/ std lash 2.2-2.4 mm
1 step up for 911C2 works well in stock engine. Hot cam for 911SC w/ 10-1 c/r
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Old 11-26-2018, 09:06 PM
  #42  
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Originally Posted by RSA964993 View Post
Great thread. Anybody have any thoughts on a 964 having a 996 Cup Clutch? I raced my RSA for years and putting it back to street duty. Between the light weight flywheel and the 996 Cup clutch it's just about impossible to have a smooth take off or have the car stall when I come to a stop. I'm assuming that a clutch swap out to stock (or is there a better alternative?) and going to the heavier flywheel are in order. I feel like I'm highjacking the thread but it seems many that are chiming in my have some thoughts.

What are the differences? I just helped drop an engine from a 996 Cup car with over 350 original hours on it. Yes I know.

The pressure plate looks the same as on my 964 turbo the flywheel is RS lightweight as i am using on my 993 engine build. I have a similar setup in my 964 C2 and it doesn't stall but I have a chip.
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Old 11-26-2018, 09:55 PM
  #43  
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The transition is instant, as in an on/off switch. There is no slow, smooth take off. If you attempt to do a slow take off that the car just shudders. Very much a race clutch. I think I was told it's a triple disc Sachs clutch. It came off of a 996 Cup. Once I'm rolling it's incredibly quick and deliberate. Great for a race track. The chip is supposedly a custom chip which I'm thinking is pretty old and never really suited the car unless it was on a race track. I think I'm going to get a chip from 911chips because it seems to address the light weight fly wheel issue and it's papencity to stall when I come to a stop or the engine RPMs being low.
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Old 11-26-2018, 10:57 PM
  #44  
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Originally Posted by RSA964993 View Post
The transition is instant, as in an on/off switch. There is no slow, smooth take off. If you attempt to do a slow take off that the car just shudders. Very much a race clutch. I think I was told it's a triple disc Sachs clutch. It came off of a 996 Cup. Once I'm rolling it's incredibly quick and deliberate. Great for a race track. The chip is supposedly a custom chip which I'm thinking is pretty old and never really suited the car unless it was on a race track. I think I'm going to get a chip from 911chips because it seems to address the light weight fly wheel issue and it's papencity to stall when I come to a stop or the engine RPMs being low.
I think you are talking about the multi disc Tilton Carbon clutch they also used in the CGT. Didn't realize Aasco owned them along with Carillo and others. http://www.aascomotorsports.com/tilton/clutches.html measures about 5.5" across. The one we just opened up has the stock turbo clutch it must have been switched on the Cup car. The Tilton's like most race clutches need to be engaged and driven hard. You don't want to slip them or you will destroy them quickly. I was looking at one for my track build but decided it wasn't worth it. The kit is expensive the replacement discs cheap but I don't need the headaches. I will try to take pictures tomorrow and see if it is the same you are talking about. As far as I can tell the mounting to the crank is identical.
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Old 11-27-2018, 11:46 AM
  #45  
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Originally Posted by Bill Verburg View Post
What am I, chopped liver? if you guys don't care for my input I'd be happy to stop posting
No, just pate :-) Thanks for all the posts. Gear ratios, while not permanent, are expensive changes :-) Hence my over analyzing. I literally have a dozen charts printed out. What I need to do is go drive a car that has the gears I think I want in it. I think I'm most concerned on 3-4 on the street, are they still in the 'fun zone' - not luggy, not too revvy.

These are the ratios I'm considering:
Tire diameter 25.8"
Final: 3.444
1st - 3.154
2nd - 2.176
3rd - 1.526
4th - 1.174
5th - .868 (stock)
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