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 > 911 / 930 Turbo & Super Charging Forum


Reply
 
LinkBack Thread Tools Rating: Thread Rating: 1 votes, 5.00 average.
Author
Thread Post New Thread    Reply
Registered User
 
Join Date: Jun 2008
Location: Connecticut
Posts: 121
Garage
Pretty cool car acceleration calculator

I stumbled across this car acceleration calculator the other day and I found it to be a pretty fascinating way to test how different variables will affect the acceleration of my car. Has inputs for pretty much all the important factors: weight, gear ratios, shift speeds, aero factors and most importantly it allows you to plot the exact rear wheel torque curve of your vehicle (just take your wheel dyno figures and plug them in by clicking and dragging the bubbles to the correct figures using say 200rpm increments).

I dont have access to a Vbox, nor do I really want to try testing say 60-120mph acceleration around where I live, so this is a great way to generate some theoretical numbers. I would think that if you input the data correctly the model comes pretty darn close because 60-120mph takes driver skill and launch technique out of the equation .....


Here is the link:


http://vlsicad.ucsd.edu/~sharma/Potpourri/perf_est.html

Old 11-21-2009, 08:27 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #1 (permalink)
Registered User
 
Join Date: Jun 2008
Location: Connecticut
Posts: 121
Garage
Just curious if anyone here has aero information on the factory 993 GT2 Evo? For this model I took the figures from a stock 993 and then made the frontal area and Cd figures slightly worse to account for the flares and large rear banana wing. Does anyone know the aero stats for a 80s 930?

Changing the aero figures desnt make much of a difference in terms of the 60-120mph times but changes the top speed a bit.
Old 11-22-2009, 07:36 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #2 (permalink)
Infidel
 
JBL930's Avatar
 
Join Date: May 2006
Location: UK
Posts: 1,172
The 930 has a Drag Coefficient of 0.4 according to this 1978 Porsche 930 Turbo - Porsche - Get Car Specs - Car specifications with thousands of models from all car makers

Frontal area is going to be between 15 and 20 sq ft, at a guess.

My 930 does 60-120mph in 6 seconds dead



The run was with stock wheels and stock 4 speed gearing, engine is roughly 500bhp, i weigh about 190lbs, and car weighs around 3000lbs with fuel. Does that add up with the calculator? I've tried playing with it but can't seam to get anything out of it.

Thought as i can give you some actual figures you may be able to test it
__________________
Jonathan.
87 930, 993 turbo engine, RS Tuning 520PS/515lbf-ft, Arrow Rods, ARP hardware, Solid lifters, G50-50, RS Flywheel, 890nm Sachs clutch, RSR coil overs all round, 993 C4 calipers front, 930 fronts on the rear, Ruf Speedlines.....
Old 540 BMW, XB12S Modified, for being a total hooligan
Old 11-22-2009, 10:47 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #3 (permalink)
Registered User
 
Join Date: Jun 2008
Location: Connecticut
Posts: 121
Garage
That sounds about right for a 500hp stock weight 930. Do you have a chassis dyno sheet to plug the exact power curve in? For my car - 2200lbs + me (200lbs) and 585rwhp with 345/30/18s and a 4 speed with shortened 2,3 and 4th gears the model spits out 4.25 seconds 60-120mph.
Old 11-22-2009, 12:18 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #4 (permalink)
Infidel
 
JBL930's Avatar
 
Join Date: May 2006
Location: UK
Posts: 1,172
Here is the dyno sheet, it doesn't have the blip in the boost between 3700 and 4500rpm when it's on the road, must be something to do with the load on the rollers?



No way you could do it in 4.25 seconds though, Dknebes with something like 780 rwhp managed 60-130 in 6.5 seconds, my 60-130 is 7.53 seconds, at a guess you'd be somewhere in the middle.
It takes me 1.5 seconds for that last 10mph, let's say you only need 1.25 seconds, and your 60-130 is 7 seconds, you're going to be at around 5.75 seconds to 120, nowhere near 4.25!! The calculations are unrealistic.
The only way to know for sure is get yourself a VBox or AX22 and do some runs, a nice level road and no obstructions!
__________________
Jonathan.
87 930, 993 turbo engine, RS Tuning 520PS/515lbf-ft, Arrow Rods, ARP hardware, Solid lifters, G50-50, RS Flywheel, 890nm Sachs clutch, RSR coil overs all round, 993 C4 calipers front, 930 fronts on the rear, Ruf Speedlines.....
Old 540 BMW, XB12S Modified, for being a total hooligan

Last edited by JBL930; 11-22-2009 at 01:22 PM..
Old 11-22-2009, 01:03 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #5 (permalink)
Registered User
 
Join Date: Jun 2008
Location: Connecticut
Posts: 121
Garage
Yeah it might be a bit optimistic. Does that 780whp car have stock weight and gearing? I guess the only way to find out is to borrow someone's Vbox. I have a buddy with a fast 996 Turbo who might lend me his...

Last edited by GT2EvoGuy; 11-22-2009 at 02:31 PM..
Old 11-22-2009, 02:25 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #6 (permalink)
Infidel
 
JBL930's Avatar
 
Join Date: May 2006
Location: UK
Posts: 1,172
I don't know what Dknebes' car weighs, or what gearing he runs, your car should be a lot LOT quicker than mine with your power and weight. Borrow your mates VBox and do some runs, would be great to see some more 60-130mph runs on our modded 930's, it only seams to be the 993, 996 and 997 crowd that are interested in this test.
Dyno figures are all well and good, but real world performance is where it's at, and this is the best test, it even shows if you're slow with the gear changes, my gear changes take over half a second which is snail pace
I'll be doing some 0-300kph runs soon, looking forward to that
__________________
Jonathan.
87 930, 993 turbo engine, RS Tuning 520PS/515lbf-ft, Arrow Rods, ARP hardware, Solid lifters, G50-50, RS Flywheel, 890nm Sachs clutch, RSR coil overs all round, 993 C4 calipers front, 930 fronts on the rear, Ruf Speedlines.....
Old 540 BMW, XB12S Modified, for being a total hooligan
Old 11-22-2009, 02:34 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #7 (permalink)
Infidel
 
JBL930's Avatar
 
Join Date: May 2006
Location: UK
Posts: 1,172
A bit of info on his car here Dyno pull 733rwhp 89 930 - Rennlist Discussion Forums
I got the power figure wrong, actually 733rwhp. Although i believe he's over 800hp now if you look at his sig No idea what boost level?
Two shifts would mean he has to be running a G50 not a 4 speed, no mention of weight though
It's a seriously quick car, as i said these 60-130+ runs really show what you have, would love to know what Bello's car does it in
__________________
Jonathan.
87 930, 993 turbo engine, RS Tuning 520PS/515lbf-ft, Arrow Rods, ARP hardware, Solid lifters, G50-50, RS Flywheel, 890nm Sachs clutch, RSR coil overs all round, 993 C4 calipers front, 930 fronts on the rear, Ruf Speedlines.....
Old 540 BMW, XB12S Modified, for being a total hooligan
Old 11-22-2009, 04:38 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #8 (permalink)
Blackbird Pilot
 
Reaper930's Avatar
 
Join Date: Jul 2007
Location: The OC
Posts: 2,112
When my motor is retuned in Feb I'm going to be doing some 60-130 and 0-150mph runs with a databox. Geez I can't wait until then...
__________________
Reaper | The Outlaw 930 Hotrod Gruppe Fünf Gruppen.com | The Baddest 934/5 Parts for the 911/930 D-Zug.us
Old 11-22-2009, 04:53 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #9 (permalink)
Infidel
 
JBL930's Avatar
 
Join Date: May 2006
Location: UK
Posts: 1,172
Gabe, would love to see what your times are!! We will have to start a thread on here dedicated to it. The problem is when some people are told by their tuner that they have 400-500-600-700 whatever hp, then they do a 60-130 run and it's clear that something doesn't add up, they very rarely, if ever, post their results!
It happend to me, i was told my old engine was 497bhp, my 60-130 runs were about 10.5 seconds which would point to near 400bhp, which it turned out was closer to the truth, i didn't mind sharing the info though.
If you can get a 0-300kph done somewhere that would be awesome, are you planning on doing any Texas Mile style events with your car?
__________________
Jonathan.
87 930, 993 turbo engine, RS Tuning 520PS/515lbf-ft, Arrow Rods, ARP hardware, Solid lifters, G50-50, RS Flywheel, 890nm Sachs clutch, RSR coil overs all round, 993 C4 calipers front, 930 fronts on the rear, Ruf Speedlines.....
Old 540 BMW, XB12S Modified, for being a total hooligan
Old 11-22-2009, 05:19 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #10 (permalink)
Blackbird Pilot
 
Reaper930's Avatar
 
Join Date: Jul 2007
Location: The OC
Posts: 2,112
I'll see what's availible in Feb, but most likely i'll be able to get some kind of number up to 150, the goal would be to do a mile event but we'll see.

On the power figures, i'm not worried about it, we were seeing 576 ft lbs of tq at the rear wheels with a fcuked up fuel map and lean spots on 1.2 bar at 4,400 rpm. I can light up my rear tires (345 Comp slicks) in 3rd gear on full boost when warm...so power isn't going to be an issue.

With the MOTEC tuning we're going to do gear dependant boost so we'll net the fastest times as traction will not be an issue any longer. I really, really want to rival the factory's numbers of the 935/76 with a 0-150 of 11 seconds. I figure with a extra .6 liters of discplacement and the advantage of EFI and a modern setup we can do it.

Regardless of the numbers and output we get i'll post it along with video and pix - we can't truly appreciate the early factory efforts and what they did until we take an "ultimate" modern motor and see how it stacks up against the "out of date" stuff done way back when. I for one think the factory was way ahead in terms of what they were able to accomplish...
__________________
Reaper | The Outlaw 930 Hotrod Gruppe Fünf Gruppen.com | The Baddest 934/5 Parts for the 911/930 D-Zug.us
Old 11-22-2009, 07:03 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #11 (permalink)
Registered User
 
Join Date: Jun 2008
Location: Connecticut
Posts: 121
Garage
Hi JBL,

So out of curiosity I inputed your car's values into the calculator as best as I could. The output the calculator came up with was 60-120mph in 6.25 seconds. Not that far off your actual time of 6.0 seconds on the Vbox.

To get this output I used the values you gave me:

Weight 3000lbs
Drag Coefficient 0.4
Frontal area 20ft

I plotted your rear wheel torque curve into the chart section at 500rpm increments just eyeballing your sheet as closely as I could (I had to guess at the 7000 figure but im thinking you shifted around 6500 max anyway):

3000 - 327
3500 - 433
4000 - 490
4500 - 528
5000 - 520
5500 - 471
6000 - 431
6500 - 401
7000 - 350

Stock 4 speed so gearing is:

2.25
1.304
.892
.625
4.22 final drive

245/45/16 tires

190lb driver
600ms shift time (you said just over half second)

I wish I had more actual Vbox results to compare to the calculated results but in this case the calculator comes pretty close.
Old 11-22-2009, 08:36 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #12 (permalink)
 
Infidel
 
JBL930's Avatar
 
Join Date: May 2006
Location: UK
Posts: 1,172
You're right, it does come close! I reduced the frontal area to 15 sq ft and it comes out at 6 seconds. Even the HP graph comes out close!! Remember my dyno sheet shows calculated FWHP numbers, not rear wheel, i assume that is what it is asking for?
Most chassis dyno's read over so i would bs shocked if my actual power was really as high as the graphs show. But for this excersise it certainly looks close!!

Gabe, i'm not questioning the power of your car, the point i was making was that we will get very few people stepping forward with their findings, as a lot will realise they do not have the power they are told they have. But hopefully we can get plently of people to properly test their cars and get a database going, will be a great comparisson tool for those going up the power ladder, and also a great tool between mods to see if you are moving in the right direction


EvoGuy, here's the data from that calculator, i've put the same ratio's in as you said, and as close to the torque figures as you. Will be interesting to see what it's going to do with the new wheels. It says my top speed with the old wheels was 186, i actually managed 187.4mph, i'm not sure if was at the rev limit but i knew i was close



__________________
Jonathan.
87 930, 993 turbo engine, RS Tuning 520PS/515lbf-ft, Arrow Rods, ARP hardware, Solid lifters, G50-50, RS Flywheel, 890nm Sachs clutch, RSR coil overs all round, 993 C4 calipers front, 930 fronts on the rear, Ruf Speedlines.....
Old 540 BMW, XB12S Modified, for being a total hooligan
Old 11-23-2009, 02:01 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #13 (permalink)
Infidel
 
JBL930's Avatar
 
Join Date: May 2006
Location: UK
Posts: 1,172
Just done one with the new rear tire sizes 285/40/17, top speed should now be a possible 205mph (given enough power and long enough road)!
What is interesting is that my 60-120 time has gone up! I actually suspected this from driving it, it doesn't pick up as quickly with the bigger wheels, i will do some runs when i can and check against it.



__________________
Jonathan.
87 930, 993 turbo engine, RS Tuning 520PS/515lbf-ft, Arrow Rods, ARP hardware, Solid lifters, G50-50, RS Flywheel, 890nm Sachs clutch, RSR coil overs all round, 993 C4 calipers front, 930 fronts on the rear, Ruf Speedlines.....
Old 540 BMW, XB12S Modified, for being a total hooligan

Last edited by JBL930; 11-23-2009 at 04:57 AM..
Old 11-23-2009, 04:52 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #14 (permalink)
Large Member
 
krasuskyp's Avatar
 
Join Date: Nov 2001
Location: top of 3rd
Posts: 4,244
Garage
Quote:
Originally Posted by GT2EvoGuy View Post
Yeah it might be a bit optimistic. Does that 780whp car have stock weight and gearing? I guess the only way to find out is to borrow someone's Vbox. I have a buddy with a fast 996 Turbo who might lend me his...

Mr. EvoGuy...

Where in CT you at? I've got an AC-22 you can use anytime. Similar to AX-22 but prehistoric and no where near as shmancy but it effectively measures all parameters, just can't dump them (AP-22 could, it's prehistoric sibling).

LMK, happy to help and it'd be cool to meet. Love to see that car, sounds astounding. I'm 2mi off 84 near UCONN in the NE corner here...
__________________
Paul... CT | '87 930 | '08 M3 6gang vert |
past:

| '07 S6 | '98 M3 vert | '01 M5 | '96 993 C2 cab | '05 S600 Sport - biturbo V12@Just Not Right 495rwhp / 612rwtq |
| '58 TR3A | '01 S8 | '95 S6 6gang | '88 M5 | '87 190E 2.3-16 |
Old 11-23-2009, 05:14 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #15 (permalink)
Registered User
 
Join Date: Jun 2008
Location: Connecticut
Posts: 121
Garage
JBL,

Yes the calculator requires that you input the rear wheel torque curve. The Dyno Dynamics power curve for your car showes rear wheel figures correct? - ie peak rear wheel HP of about 500 and about 530lbs of peak wheel torque?
Old 11-23-2009, 05:15 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #16 (permalink)
Registered User
 
Join Date: Jun 2008
Location: Connecticut
Posts: 121
Garage
Hi Paul,

Im in the Stamford area. I just asked my buddy in Stratford with the 996 turbo and he thinks he can get his hands on a Vbox for us to do some testing with. His 2004 996T now makes 720hp and 780tq to the wheels! Now to scope out flat locations where one can prudently do the test.....
Old 11-23-2009, 05:19 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #17 (permalink)
Infidel
 
JBL930's Avatar
 
Join Date: May 2006
Location: UK
Posts: 1,172
Quote:
Originally Posted by GT2EvoGuy View Post
JBL,

Yes the calculator requires that you input the rear wheel torque curve. The Dyno Dynamics power curve for your car showes rear wheel figures correct? - ie peak rear wheel HP of about 500 and about 530lbs of peak wheel torque?
No mate, my graph shows corrected flywheel HP, it says so on the graph! If that was my actual rear wheel torque i'd be at nearly 600 ft lb's at the flywheel (which would be over 810nm), which simply isn't possible with my set up and boost level. I'm only at a little below 1.1bar with twin K16/24's. I'd need to be at 1.3 bar and running very special K24/26's, plus twin plug and race cats to get anywhere near those numbers.

If i've input my figures correctly and it's given a time of what i can actually prove, then i can only assume it is asking for flywheel HP. Otherwise it really is miles off
__________________
Jonathan.
87 930, 993 turbo engine, RS Tuning 520PS/515lbf-ft, Arrow Rods, ARP hardware, Solid lifters, G50-50, RS Flywheel, 890nm Sachs clutch, RSR coil overs all round, 993 C4 calipers front, 930 fronts on the rear, Ruf Speedlines.....
Old 540 BMW, XB12S Modified, for being a total hooligan
Old 11-23-2009, 05:37 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #18 (permalink)
Blackbird Pilot
 
Reaper930's Avatar
 
Join Date: Jul 2007
Location: The OC
Posts: 2,112
Okay so here's my info based upon my RWTQ numbers run at 1 bar at 605 hp & tq:






__________________
Reaper | The Outlaw 930 Hotrod Gruppe Fünf Gruppen.com | The Baddest 934/5 Parts for the 911/930 D-Zug.us
Old 11-23-2009, 07:26 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #19 (permalink)
Blackbird Pilot
 
Reaper930's Avatar
 
Join Date: Jul 2007
Location: The OC
Posts: 2,112
Here's the input theoretically with 880hp...when we retune with MOTEC and run it to 8,000 RPM and have ultimate in traction control, i'm highly skeptical of the numbers listed, but it would be nice to see 71 mph in 1st gear with an 8k rev limit.

So when we retune that will be the goal:






__________________
Reaper | The Outlaw 930 Hotrod Gruppe Fünf Gruppen.com | The Baddest 934/5 Parts for the 911/930 D-Zug.us
Old 11-23-2009, 08:06 PM
  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 04:33 AM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2020 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.