Oldsmobile Aurora: Acceleration

garnes

Well, I guess I'm the only one that thinks the C&D times posted way back for an autobahn are likely straight. I know this has been beat to death a long time ago.

Musclecar97 has a good point about 800's car not having the 3.71. The regular 3.48 is not that much different really, but I think the 3.71 would show up in the times. So 800, you are not comparing apples and apples there. Also, there are a lot of other factors with your results - namely no launch rpms and a hot summer day.

Is anybody going to parallel the "rolling" start times listed for cars by C&D??? I may very well be clueless as to what this means, but it seems to be a measure of the car's acceleration with no launch from a roll of 5 mph (at idle I'm sure). The time differences from a launch are large.

I still think 800's, Musclecar's, and RJS's times are great considering all the negative factors involved. Come on, you guys are about matching the "special juiced" car with some simple mods (come on the air box and a K&N adds 8 to 10 HP at the engine at the top rpms - that's not a whole lot but a nice start) and then running on bad tires or not launching, running a 3.48, and running on a hot day.

If you did everything right like the pro's, I'd expect some better times. I'd bet some major differences and lower times than that "mystery car from 94 - oooh". If it was truly different, you guys shouldn't even come close - let alone almost match it with all the compromises made at the track.

I don't know, I'm reading all the results and I'm thinking WOW, that's really good - when you look at the whole picture.

As for the "juiced car" thing well, the the classic weighs 160+ lbs more than the new Aurora, but has significantly more power throughout it's curve - especially torque. The new Aurora did have some more HP at the top of the curve though. All in all, I'd expect both cars equipped with a 3.71 to perform pretty darn near the same, and with C&D they did. Go ahead, beat me up for over simplifying, but I don't think there are a lot of differences between the two cars when you cut to the bottom line of power & weight with so much between the cars being the same.

rjs200240

Garnes: "Is anybody going to parallel the "rolling" start times listed for cars by C&D??? I may very well be clueless as to what this means, but it seems to be a measure of the car's acceleration with no launch from a roll of 5 mph (at idle I'm sure). The time differences from a launch are large."

Well, what was the time for the 5-60? I think they mainly use it as a measure of the car without the clutch-dumping advantage. I doubt the time varies as much from the 0-60 time for automatics as it does for manual cars. It's hard to imagine how they accurately time the 5-60 since it isn't like they can start once the car starts moving (as they can with the laser gun). I would think they'd have to signal the driver or something. I suppose there is some reaction time between starting the clock and hammering the throttle. At the track, this time is taken into the RT. I think pre-loading the engine mainly affects the RT at the track. If you just mash the throttle once the light turns, there will be a slight pause while the engine builds revs, but I doubt you'd pass the timing light. I'm sure pre-loading (revving) the engine has some benefit to the ET, but I would guess it would mainly affect the RT. But I could certainly be wrong.

For 1/4 mile times, the "wringer" argument doesn't really matter. Who cares (Ok, I know, I started the argument. But it's been argued. And it can't really be proved anyway since that car has probably long been crushed). It won't make your car any faster or slower no matter what magazine is right. Your car'll do what it'll do. We all think our car will be faster under better conditions, so let's all go back when it's better. It's a lot of fun and it's pretty cheap, so there's no reason not to. Even if I never get better than a 16.05 (although I hope like heck that's not the case!!) I still love the way my car drives, and I love the power when I punch it. If it's only 16 second power, well who cares. It feels good to me.

Taylor, I thought your car was an autobahn. No?

garnes

I guess I could dig up some other car's test times. I don't have that Aurora thing. I'd think they have some way of accurately measuring the 5 to ... thing.

I hear you about "it is what it is". Still, I'm impressed with what you guys have done.

rjs200240

I went and dug them up... I guess I should just have a drawer with Aurora articles so I don't have to keep pulling boxes out in the garage. The 2001 Aurora had a 0-60 time of 7.6 seconds and a 5-60 time of 7.7 seconds. For the classic, the 0-60 time was 7.4 seconds and the 5-60 time was also 7.4 seconds. These times are all from Car and Driver. So I don't think that there is much to make from them.

P.S. In one of the photo shots from the classic review, the engine cover says "Aurora V8 Wringed Exclusively for Oldsmobile" :P

fdion

Both auroras classic and S2 should pull at sea level a 7.4 consistantly, the weight offsetting the powerband advantage. I was under the impression that the classic would be slightly slower, but after calculating this again and again, they should be neck and neck.

I get 7.5 @up to 95 farenheit, consistantly in High Point, NC on my S2. I use a computer to calculate the exact time difference, not relying on a G tech (notoriously optimistic - once told me that my 205hp @ flywheel 505 turbo was putting out 215hp RWP!)

At about 80 farenheit, the 1/4 should be about 15.8@ 89 mph for the classic and 15.8@ 90mph for the S2, with a few gallons of gasoline, no spare/tools and a 150lbs driver. I haven't had the chance to do a 1/4 mile, but I'd expect 15.9-16.0 correcting for altitude. Ah, and my hitch, that will definitely keep me on the wrong side of 16

Are you guys logging your runs thru odb2? It would be really interesting to look at that since in mode 1 you get rpm vs pounds of air per minute getting metered by the MAF and other interesting stuff like that (even intake temperature). In fact, it's a more precise way to measure the effect of any mods than a dyno, and as long as you note also the barometric pressure, it's easy to calculate the correction.

All you need is a laptop that can run at least windows 95 and an odbc cable and software. You can get a cable and software for $120 without any GM specific codes to $289 for one with the extended code. Well worth it IMHO, much more than a gtech or the like.

Ciao,
Francois

800wattaurora

I still love my Aurora no matter what time it gets. I bought it for it's unique style and it's luxury ride, and the V8. I had alot of fun that night at the track, even with a 15.8. The Autobaun gearing makes me feel better though, my 96 is NOT autobaun equiped, 3.48 for me. So I guess my time could be lower if I only knew Autobaun packaged exisited when I bought it +2 years ago. If I only would of done my homework. Next auto purchase will be heavily pre-researched thru the net. Doesn't matter now. I like my Aurora and don't plan on getting ride of it any time soon. It's almost paid off, no car payment will be nice.

Do you guys think if my tranny ever goes, I could swap in the Autobaun? Probably could be done, don't see why it couldn't. Didnt the Autobaun option only cost like $350-400? Can't believe the previous owner didn't get it. I think my next ride will be a used STSi in 3-4 years. Hopefully the Aurora will run trouble-free till than. I've replaced most of the common diseases already, only have that AC-compressor-virus left to go.

Next track outing for me should be within a month or so. One of my friends just picked up a 91 Mitsu Galant VR4. For those who don't know, the VR4 is HIGH-performance Turbo, only offered 91-92, only 3,000 produced total. His came with the works down to it, stage 3 turbo up grade and much more. The previous owner blew something up, and sold it as is for $1,600. Turned out to be the just the Radiator. What a steal!!! He know engines though so he can work on it himself, I plan on picking his brain in the process. Well go to the track soon. My other buddy was made that I didn't tell him I was going, He recieved a FREE 69'Camero, built 350. Runs STRONG body is crying for rust-repair though.

Anyways next time, I'll Have my heat-shield up, maybe 100 Octane, and only 1/4 tank. Don't plan on taking the weight loss program either. Musclecar- didn't you also take some stuff out? Maybe I should, My luck, I'll get a flat on the way. Also think that the way I had my Cone resting on the bottom couldn't of helped either, whatever, I still love my car regardless!!!

800wattAURORA

musclecar97

Yes I had the spare tire and jack out and only 1/3 of a tank of gas. Also I skipped the donuts for breakfast that day. I was also worried about getting a flat on the way to the track since my tires at the time were on their last legs. I had everything in the car when I went, but the day I went there was a car show going on and people who entered their cars in the show got to run the track. I entered the show and actually got a trophy in the show and shine for 2nd place in the 1990 and newer class. I made a plaque to go in the front liscense plate out of the checkered flag aurora v8 logo and it looked sharp. Anyways I put the spare and jack in the car show area where I was parked.

Great info fdion....keep it coming

sbeaupre

Garnes - yes 21lbs is a lot for a street car...I ran 17-18 day in day out and 20 or so when I was felling "lucky"

The 5-60 C&D times really only apply much to manual transmissions. This basically takes out the big time advantages derived from "clever" clutching that the average driver may not be able to reproduce. That's why you don't see much (or any) time dif's with the automatic Aurora's

Taylor...your friend is VERY lucky to have a VR4. Have him check out www.buschurracing.com...unbelievable.

I'll ask one more time...same rules still, no laughing: Anyone have thoughts on the ERam????

garnes

fdion - perhaps I'm not at all a sophisticated car owner, but what you are saying about the OBDII and extracting that kind of information from it sounds incredible. Thanks. Can you explain "I get 7.5 @up to 95 farenheit, consistently in High Point, NC on my S2."? You've measured some runs? Calculated something?

Thanks all for the 0-60 and 5-60 as it relates to manual and automatic transmissions. If "0 to" and "5 to" times are the same for an automatic, then there is certainly a little extra pop for bringing the rpm's up a little.

800 - We may be shopping for the same car in the future. I'm thinking more like 5 years from now. I just want to say this again - all things considered your times are great IMHO. I wouldn't worry about 3.71 vs 3.48. I think you are talking several thousand dollars to make changes. For comparison (I'm guessing here so don't pound on me if I'm off guys) I think the Caddies that don't have the 3.71 have something like a 3.11?? It seems to make a difference to 60 something like 7.4 vs 6.8??? Anybody with more/other info please share it.

fdion

If somebody can give me the gearing of the tranny on the non-autobahn version, I can calculate the estimated 1/4 mile time/speed.

Francois

fdion

I've measured the runs. You might remember me posting the details about a year ago. I used a compaq ipaq and a laptop to record the runs. It then involved using sound forge and matching the run to rpm data. I would now use obd2 instead of this much more complicated method (man, I spelled obd2 as odbc in my previous post! spending too much time with database programming...).

Francois

rjs200240

The non-autobahn Aurora is 3.48, the autobahn and new Aurora is 3.71. The non "T" caddies (as in not the STS, ETC, DTS) have 3.11 and the "T" caddies have a 3.71. The tranny gears are the same with 2.96, 1.63, 1.00, and 0.68.

garnes

Let's have that calculation for the 3.48. I'll bet 800wattaurora is most interested. You will be converting oranges back to apples for him/us.

I'll guess what the difference is just for fun -.2 seconds (to 60) and .3 seconds in the 1/4 mile. Just guessing.

Tell us how you do it. Also, an explanation of that efficiency calc thing would be neat.

Thanks.

fdion

My arms are tired from calculations, so I decided to write a little program. It'll make things a little easier on me as we test different conditions.

What are the dimensions of the tires on the non-autobahn? same as the 16" autobahn classic?

Francois

fdion

Calculating by hand I was taking a few shortcuts, however it is impresive how close I was from a computer iteration done to the 1/100th of a second.

The basic equations are of course F=ma and v=u+at. However, this is assuming constant acceleration. One can calculate this for 1st gear, 2nd gear, 3rd gear and so on or even for 1st gear up to 3K rpm, 1st gear above 3K etc and add it all up. This is basically what I was doing by hand. Takes forever.

So I wrote a few c++ objects, one for the engine, one for the transaxle, and made a loop that increases the time by 1/100th of a second. I calculated the instantaneous acceleration at that given time, given the rpm and gear selected. For example, calculating the torque at the differential, I multiply the engine torque by the ratios. With a few more terms and you calculate the acceleration:

engine northstar(3.995); // in liters, also possible to use CI: northstar(244);

northstar.setTorque(CLASSIC);

transaxle tranny(true); //is it autobahn?
                        //if different ratio, use:
                        //tranny.setFinalRatio(3.11);

acceleration = uc * factor * northstar.torque(rpm) * tranny.GearRatio(gear) * tranny.getFinalRatio()/(mass * tireRadius);

Notice the function of torque based on rpm. This was hard to do in particular to simulate the realistic slippage of the tranny as it goes from 1st gear disengaged to 1st gear engaged. I simulated that by starting the rpm at 0 and applying the torque in a particular way until 900 rpm which is idle speed.

In turn, I used the acceleration to calculate the speed increase during that timeslice, taking into account mechanical losses and aerodynamic drag (assuming a cx of .36). By calculating the number of revolutions the engine (a little tricky) did since last timeslice, one can calculate how far the car moved.

At 6200rpm, I automatically shifted to the next gear. Third gear in real life would not stay until 6200 and my simulation shows it barely makes it to 4th gear at that speed on the autobahn and S2 (both 3.71) and just stays in 3rd on the 3.48 transaxle (assuming a bypassed speed limiter).

Also, each time the tranny shifts, the rpm has to drop before the tranny reengage and there is slippage and that creates a lag in acceleration. It takes 0.6 seconds before torque is again fully applied. It might be 0.7 in real life, I dont have engineering specs on the transaxle and tranny computer.

Note: This is pretty much the real deal, as long as you truely have an engine putting out 260ftlbs @ 4.4K and 250hp @ 5600 rpm and it's reasonably close to the torque curves published by Oldsmobile, you are at sea level, normal atmospheric pressure and humidity and 20 degrees celcius (68 degrees farenheit).

Francois

fdion

Volumetric efficiency is the ability of the engine to fill it's cylinders compared to it's capacity. Now strangely enough, with more recent designs such as 32 valves, it's actually possible to get a volumetric efficiency greater than 100% without turbo or supercharging.

It is roughly (slightly simplified, taking out stuff like temperature, barometric pressure etc) defined as (in the SI system):

Ve = 2* P / v * (60/r) * (afr/ad)
-----------------------------------
Ie x Me x fc

- P is the power in hp (250)
- v is the swept volume in liters (3.995)
- r is the rpm at which the power is generated and this Ve is calculated
- afr is the stochiometric air fuel ratio (14.1 to 1)
- ad is the air density (again we are talking at 20 celcius - 68 farenheit; sea level; normal pressure; normal humidity; it is 1.2)
-Ie is the actual "measured" efficiency (usually calculated as CR/20.1, where CR is compression ratio)
-Me is the mechanical efficiency (friction, heat transfer to coolant, heat loss through radiator etc)
-fc is the fuel net calorific value which in the US is 42.95

If we plug away the numbers:

Ve = 2 * 250 / 3.995 * 60/5600 * 14.1/1.2
-----------------------------------------
10.3/20.1 * 0.75 * 42.95

= 15.7563 / 16.5069

= 0.9545 which is 95.45%

Rounded to the first decimal, that's 95.5% as I posted earlier this week.

Francois

fdion

What you've been waiting for (assuming 16" 235mm wide and 60% profile tires on both classic and 17" 235mm wide and 55% profile tires on 2K1):

2K1 aurora v8:
--------------
1/4 mile: 15.6s @ 90.7 mph (4086 rpm in 3rd)
0-60: 7.36s, 374.4 ft (4409 rpm in 2nd)

aurora classic autobahn:
------------------------
1/4 mile: 15.7s @ 90.2 mph (4076 rpm in 3rd)
0-60: 7.48s, 379.6 ft (4419 rpm in 2nd)

aurora classic 3.48 (non autobahn):
-----------------------------------
1/4 mile: 15.85s @ 90.3 mph (3773 rpm in 3rd)
0-60: 7.84s, 396.5 ft (4085 rpm in 3rd)

Francois

homer2000ssei

Gentlemen - gentlemen

Am I glad I remembered Edmunds now. Ignore my screen name, i came up with it when i recieved my 2000 SSEi,back in - yup, you guessed it Oct 2000.
I hung around the SSEi forum for a while - then moved along - and it looks like I may be back with my second favorite car. I am a few hours from (likely) purchasing a 97 Aurora. I just had it at the dealership to be checked out mechanically etc - and they came back with an interesting report on the car. I have read through a few of the threads here, and it looks like I might be able to take advantage of your experiences. I wasnt so lucky with the last car, having one of the first - and one of the few that ever became modified, there wasnt a lot of knowledge around. I see you guys have been taking the Aurora to the right places - a 1/4 track. Ive been going all sumer with my '80 Z28 that has had some work done to it - and if i take the Aurora, Ill be looking to make some changes on it too. Nothing like a nice 4 door family car whippin' down the dragstrip (and with a decent time )

heres what Im looking at.
1997 - 180,000 KM (thats maybe 115,000Miles).
it has a cool green/blue tint paint, with blue leather, and all the usual interior options, including heated seats (im in canada) multi cd changer in the trunk.

I see it has a relatively new ac compressor, a new starter last week (i saw the repair bill $900). It had the 100,000M tune up a few months ago, plus some other maintenance items ($2000) - all GM parts , wires plugs etc etc.

heres some of my concerns, and you can help.

one rear shock is leaking (whats that gonna cost)
the steering rack is starting to show some wear(nothing serious yet)
there is eveidence of some oil leaking
it passed an emissions test with very flying colours (so i assume the engine is running well)

and some questions

what is an autobahn edition ( i see mention of it here)

suggest a good all season tire for it please

are cross-drilled rotors good on this heavy beast? any brand fav's

what about aftermarket exhausts (something cat-back with a little rubmle)

what can we do right away to the car to increase hp
the airbox has to go i assume - open cone anyone? or a thrasher kit?

Thats a good start - sorry about all the queations, but i can be certain Im going to buy the car (the price in amazing for it) $7500 Canadian. and i want to play with it some . . .

by the way, i got the Bonne into 14.5's at the track . . can i get there with this 2-ton cat?

cheers

Dennis

Henry

First let me say that considering your questions, this would have been better posted on the main board.

Can I get a amen KarenS?

You did not mention price, but I have to believe that you are south of $6,000 in price. If you are going to do mods, I would suggest you go to either the 95 (its chipable) or to a 96, 98 or 99. The 97's are okay, but they have a suspension system that is unique to that year.

In relation to your other question, check the main board. We are currently rehassing the whole tire question now.

fdion

Did the 2000 bonneville ssei use the 2.97 final ratio like before? also are we talking bone stock ole buick 3.8 v6 w/ supercharger, 240hp?

If so, I'm not sure how you can achieve 14.5 with mild modifications.

The reason I'm saying this is that you need 325 hp and a torque of 340 ftlbs (if you keep the torque and hp curves shape similar to the stock ones) to move that car down the 1320 with a 14.5 s timeslip. You'd be right about 98mph too with that kind of power.

As for the Aurora, it'll be also quite a bit of work. NOS or a supercharger will get you there with your fingers in your nose, but that's not motor horsepower. All motor is much more interesting. At any rate, CDN$7500 is an incredible price for such a car. When I was in Montreal a few weeks back, I saw a 97 in the paper for CDN$14000. And a 98 for CDN$19000. Both are priced within market. Remember, that car sold for about CDN$55000 in 97.

Francois

fdion

If anybody wants me to calculate what they should get for their car weight (nhra scale or any other way you can figure that out), ambient temperature and elevation, let me know.

Either everybody is out of town, or? Not much reactions to my earlier posts...

Francois

Henry

I am just waiting for the video.

800wattaurora

Your numbers seem a little fast as posted before,

                         2K1 aurora v8:

                          --------------

                          1/4 mile: 15.6s @ 90.7 mph (4086 rpm in 3rd)

                          0-60: 7.36s, 374.4 ft (4409 rpm in 2nd)

                          aurora classic autobahn:

                          ------------------------

                          1/4 mile: 15.7s @ 90.2 mph (4076 rpm in 3rd)

                          0-60: 7.48s, 379.6 ft (4419 rpm in 2nd)

                          aurora classic 3.48 (non autobahn):

                          -----------------------------------

                          1/4 mile: 15.85s @ 90.3 mph (3773 rpm in 3rd)

                          0-60: 7.84s, 396.5 ft (4085 rpm in 3rd)

What temps did you calculate @ for this? Maybe you could run it again @ 90+F.

I'd be courious to see what you #'s you'd get for me.

Non-autobaun 3.48

weight est. 3909 car+195lb driver+say 40lbs for my stereo & spare tire/jack left in+ 3/4 tank of gas don't know how much that weighs.

For HP #'s use 270hp/280tq

Temp @ 90 Alt. @ 800ft

With this conditions, Flat footed w/ shifter in 2nd (no rpm launch). I ran a 15.858@87.20 curious what your calulations come up with.

Next time I go I'll have 1/4 tank of 100 octane and launch around 1500-2000 RPMS. Hopefully it will be cooler, and I'll have my heat-shield and fender scoop in place. Maybe even my Corsa Exhaust.

 

Fdion, If you feel up to the calulations, I'm interested in seeing what I would run (with same specs as above) when it's much cooler out say 50-60, except less weigh for an extra 1/2 tank gas. Also maybe raise the HP/TQ #'s. With low-restriction exhaust maybe raise both by 10, being conservative. 280HP/290TQ. Than with some polish&ported heads add another say 20= 300HP/310TQ. With these #'s, I'm interested in seeing the time shaved.

It would be great if your up for it.

Thanks

800wattAURORA

ps- Did you check out my pics yet?

http://www.cardomain.com/id/800wattaurora

fdion

Huh?

These are just simulations, not actual runs.

Francois

fdion

I calculated at sea level and 68 farenheit. 800 feet will change things. It's amazing just how much is lost at altitude and higher temps.

How do you come up with 3909 for dry weight? They didn't have a scale at the track to get total weight? That would have been even more precise...

Also, I'll change the driver weight to 195. 150lbs is wishfull thinking on my part, I'm 180... And 3/4 of a tank, that adds a nice 6.1 lbs per gallon. How many gallons in your non autobahn classic?

Francois

Henry

It wasn't a joke.

I know they are computer simulations.

Henri

Henry

It wasn't a joke.

I know they are computer simulations.

Henri

garnes

Wow. Where did you get this stuff and learn this? Thanks.

Your calculations seem to indicate (just initial thoughts) that the 3.71 autobahn certainly pulls harder from the start, but gives back a lot of those gains after 60 mph (yes I know to 60 mph and to the 1/4 are measuring different things, but the final speed at the 1/4 is close enough to make this comparison). That was always what I initially suspected - the 3.48 being stronger at the higher speeds.

Did you use the HP and torque graphs from GM for the new aurora and the classic? For the new Aurora, I hope you at least used the graphs posted (link posted) by RJS, as they are not readily available. He had to dig to get them. The power curves for each is quite different.

homer2000ssei

Yes = point taken about posting on the main board. Im squeezed for internet time, and this forum was the last i was in when i decide dto post.

Also, i thought since I am interested in improving the acceleration etc, this was OK.

Re: mid 14 SSEi. I dont recall the gearing. it came to me running mid 15's (factory freak) and i changed the supercharger pulley and put an open cone - and voila - mid 14's . .

I have bought the 97 - a unique suspension?

Now, Ill go spend some time in the general forum

thanks

Henry

When I got work done on my 95 the guy at the dealership explained to me that Olds made a modification to the suspension system in 97. However, whatever they did, they changed their minds and changd it again for 98-99. I dont know exactly what the difference is but I am sure someone with a 97 can tell you.

rjs200240

Same guy that told you about the pivoting wheels?

fdion

Let's start with what you ran vs what I come up under simulation. Assuming normal atmospheric pressure of 1013 mBar adjusted for 800ft elevation (if you have barometric pressure in mbar or kpa it's even more precise, and you dont need to know the altitude) which would be 983.4 mBar. I also used 20 gallon as capacity x 3/4 x 6.1lbs = 91.5lbs of fuel.

>What temps did you calculate @ for this? Maybe you could run it again @ 90+F.

Under the conditions you mention:
-aurora classic
-3.48 final ratio
-temperature of 90 farenheit
-pressure 983.4 mBar (assuming normal barometric pressure for 800 ft)
-270hp/280ftlbs
-mass = 3909+195+40+91.5

As you will notice, my speed is a little off compared to what you are getting. I'm pretty sure I know why. When crossing the 1320, your 3.48 ratio is such that you just shifted in 3rd and your tranny is still in the process of reengaging, not applying 100% power. It seems that the shift to 3rd is much more lossy than the shift to 2nd as far as torque conversion goes. Since you haven't shifted yet to third for 0-60, it doesn't impact that run. A run with an obd2 log would confirm or show where/when it happens.

1/4 mile: 15.88s @ 90.4 mph (3773 rpm in 3rd) (would have been 15.73 with the autobahn diff)
0-60: 7.88s, 398.1 ft (4089 rpm in 2nd)

So, you are definitely in or around 270hp/280ftlbs. If we had a more precise mass and a true tire circumference (not calculated, measured - each brand vary ever so slightly - btw, you do have 235-60-r16 right?) we'd have a 100% reliable model of your car.

And as far as temperature goes, yes, 90 farenheit/800 feet/lots of gas, robs you of 20 hp.

So the good news is that at 68 farenheit (20 celcius) and only 4 gallons of gas you would run:
1/4 mile: 15.4 @ 91.5 (15.25! with the autobahn)

Continuing at 68 farenheit (this is the temperature the factory used to rate the aurora 4.0), but this time with the corsa and a conservative +10 hp and torque:

1/4 mile: 15.2s @ 92.7mph
0-60: 7.0s, 357.7 ft

Nice! Now let's add your last factor, the port and polish, your estimate of +20 hp and ftlbs:

1/4 mile: 14.85s @ 95mph (14.7@96.2mph with the autobahn - it's roughly good for .15s across the board)
0-60: 6.6s, 336.6 ft

Note, this is assuming you can keep your traction (you might need wider/grippier tires to do these times - plus by reducing radius by going to a lower sidewall you'd simulate the autobahn gearing and you'd run even lower times), as I do a poor job of simulating loss of traction right now. It's actually pretty complicated to do it right with Pacejka curves (I have the equations, but getting the numbers from a tire manufacturer is next to impossible unless you are a scholar with a corporate grant) and the like. You'll probably need wider/grippier tires to do these times.

Francois

rjs200240

Doesn't the curb weight of 3967lbs (where is 3909 from?) include a full tank of gas? I think the curb weight includes all fluids but no driver. So I would think you'd subtract weight if there was less fuel (a lot if the fuel is way down).

Francois, those are some impressive calculations. If you're curious on how your calcs hold up for the new car, I ran a 16.056 @ 85.77 mph on a 100 degree day with about 7 gallons used up from a full tank (according to the DIC) and I'm about 140 lbs (want me to run your car, guys?). The elevation was 500'. Traction was not a problem on a 100 degree day. The car peeled a bit for about 5-10 feet max, but didn't spin wildly at all. However, don't crunch it if you aren't interested (don't know if it's a pain or anything). I already know what it'll do given those conditions...

Also, if you want to see the torque curves as Garnes mentioned, they are here. There is a bit of a difference between them at the lower end. The classic has a bit more meat down low. The new car appears to pick up a tiny bit after the power peak over the classic.

Bob

P.S. Why the heck aren't the apostrophes (') showing up in my second paragraph?

fdion

Optional equipment will change the weight of the car too. Only an NHRA scale right after the run would tell us exactly what the weight of the car was for that 1/4 mile run. 100lbs will make a good difference, right about the same as the autobahn vs non autobahn!

That is also why I dont trust the G-tech results people post on the internet. They are worthless because people dont even know the exact weight of their car, nor if they are running on a level road (tarmacs are great). Just a 0.5% (yes, half of 1%) grade will mess up the results bad.

Regarding the curves, I use the one from the press kit I got on ebay. It's also in the nice pamphlet I got from the dealer when I bought my car, but it's smaller. I'll check but I think it's the same as the graphic you got from GM Powertrain.

As for your calculation, 16s flat sounds about right at 100 farenheit. You are only at 500 ft tough. Do you have barometric pressure printed out on your timeslip?

fdion

My simulation shows you'd get 15.99@88.3

2/100 of a second is not a big difference and just the tire pressure and true weight and barometric pressure will fluctuate the result by more than that. As for top speed, I have to go one day and run it on the 1/4 and log with my laptop the obd2 and see what is going on.

Oh, and on a 68 farenheit day you'd run:
15.66@90.2 (more than likely 88mph)

And at the freezing point, assuming no traction problems, you'd get 15.26, altough I think the mechanical efficiency would drop a bit. I haven't modeled that part yet, but is not an issue until you drop below 40.

Still, I'm happy with my simulation overall

I think at 68 farenheit, using a TB, better intake and corsa will get you south of 15s.

Francois

800wattaurora

Fdion-Thanks a lot for running the #'s. Your simulation vs. my 90 F run, close enough for me. I like those numbers. Now if I could only run on a 68 F day.

As for weight, 3909 came from left field somewhere, it's listed at 3967, don't know if that includes full fluids or what. Don't think a difference of 58lbs would cut a tenth.Close enough. Yes tires are 235-60-16, Dunlop Sport A2's. As for the 3rd gear, I shifts around the 78mph I believe. It definitly shifted before the finish line at 87.2mph.

Hum, 1/4 mile @ 15.2s with Corsa(conservitive +10) in 68F. Cait wait, that's caddyinfo material. Maybe by next year I might have the port & polish too, 1/4 mile@ 14.85s sounds even better. I'd be VERY happy to break 15. Considering getting the TPS enhancer too?

Checking the dates for TestNTune at Joliet, there last listed night is Sep. 17th. I've got a free run card, so another night at the strip is in my future. Doubt I'll have the Corsa on by then, but I'll have the heat shield in place, and probably use some 100 octane. Fdion- can you adjust for 100 back down to 93?

One of these days I'll get my Dyno graphs on disk, you guys can knock yourselves out.
Thanks again Fdion.

800wattAURORA

fdion

Taylor, you are welcome.

As far as precision of the simulation, I've added another factor. Maybe this is getting anal but I've added humidity correction.

And according to the info on the NASA site, the more humid, the higher the constant. This in turn lowers the effective air density, which in turn will make for higher 1/4 mile time, not the opposite as the old wives tale goes. It might have an impact on turbo engines with knock sensor if they are at the limit of knocking, since water will cool the cylinders, but that would not be enough to compensate for the loss of power due to lower air density.

TPS enhancer: I dont see how this would help in any way. TPS is the throttle position sensor. It might make the car feel more reponsive, but in reality this can only affect your performance and fuel economy.

Francois

garnes

Very cool. I'd say your time estimates are more than close enough. They are essentially dead on. The speeds seem a little higher though, but still really close. Incredible.

I'd sure use the graph RJS is linking to (if you aren't already) as the one in the new aurora brochure is OK for what is generally going on (although the graph from about 4000 rpm is goofed up) but is of no use for precise numbers.

Where did you get the formulas for calculating this?

Also, for estimates of time when there is a mod, you seem to be going with peak numbers. Would the actual power curves make much difference? I think they could. For example, my air box mod did not add any peak HP because all it's gains were essentially below 5000 rpm. But it added more HP than a K&N filter most of the way up to 5000.

Thanks for sharing all this.

fdion

Greg,

There is no single equation. Well, there is F=ma, but you need some meat around it. And to think that somehow car performance is in relation with an apple falling on someone's head... Sir Isaac Newton would outshine Seinfeld if he were alive.

Since there is no solution in a box, I just went with what I knew of physics and math and read a bit more on the areas I was weak in, such as meteorology (pressure, humidity, temperature and their relation with air density). Over the years I've been able to gather some info left and right, and at some point all the physics classes I took finally made sense. I dont know if this is more detail than you want, but here we go:

For some reason, manufacturers insist on pushing HP as the be all, end all figure to determine the performance of a car. Peak torque is more of a factor if you have to choose between the two, with peak HP only giving an idea of the width of the powerband.

For 0-60, 1/4 mile and the like, torque is the only way to calculate directly acceleration. So to compare apples to apples, we need to convert everything to the same thing.

If you have an HP value, you have to convert it to torque first anyway. Now all the explanations that I've seen of how you convert between torque and HP, altough come up with the right answer, seem shaky or imcomplete. I've even seen people saying "this is what it is, if you dont like it, tough!". Hopefully my explanation doesn't fall into that category!

From my physics classes in college (anybody remembers the right hand rule to determine the
direction of torque in relation to force and moment arm?):

Torque is defined as a measure of how much a force acting on a object makes it turn around a pivot. It is represented mathematically as:

t = l x F x sin (a) (1)

l is the moment arm (lenght)
F is the force
a is the angle between F and l

We also know that F = power / speed (2)

Equations 1 and 2 are simply mathematical definitions of these abstract concepts. We will come back to them later.

Now horsepower (HP) is another abstract concept that dates back to the time horses did the work (no kidding). It was officially defined as raising by 1 foot 33000 lbs in one minute. Not exactly obvious, right.

HP = 33,000 ft lbs / m

So what is the relation between HP and torque? From (1) and (2) we know that (replacing F in equation 1 with equation 2 right hand side):

t = l x power/speed x sin (a)

We can also simplify this knowing that l = 1 foot and a = 90 (sin(90)=1), because the force is applied tangentially, with no radial component. Simple trigonometry, but I can explain this further if need be.

t = 1 x power/speed x 1 or

t = power/speed (3)

Power, if expressed as 1 HP, we know is 33,000 ftlbs/m.
Speed is going to be circumference x rpm which comes out as 2 x PI x rpm.

t = 33,000/(2xPIxrpm) = 5252.11 / rpm

This is for 1 HP (33,000 ftlbs/m). It's easy to see that for rpm = 5252.11, torque and HP are equal, while for rpm < 5252 the torque will be greater than HP and for rpm > 5252 the HP will be greater than the torque.

Now, let's figure out this equation for P HP:

t = (5252.11/rpm) * P or

t = P x 5252.11
-----------
rpm

or flipping torque and hp:

P = t * rpm
-------
5252.11

Since the two are interchangeable when you know the rpm, we might as well only use torque from now on, that will save us from multiplying by the rpm and dividing by 5252.11.

We are now ready to go to part 2, F = ma

Henry

How many feet are in a mile??

garnes

5280 feet in a mile.

garnes

Thanks. I'm listening. I have to print it out and digest it though.

I actually had a ton of this stuff in college with lots of statics dynamics and loads of structural classes. I hate to say it but that stuff is way back in the dusty parts of the old bean. Funny, but the stuff I studied least is what I ended up using at work - the hydraulic stuff.

Henry

Why get so pissy over 3 feet?

800wattaurora

Found a Dragstrip reaction time tester, check it out:

http://www.greatlakesdragaway.com/sportsman.htm

800wattAURORA

http://www.cardomain.com/id/800wattaurora

garnes

I'm still waiting for part 2.

Thanks.

garnes

Man, that toupee is going to have to come off again.

Henry

Just remember to float like a butterfly and sting like a bee.

fdion

I'm working crazy hours. Going live with new B2B (ecommerce) functionality next wednesday and it's burning my spare time at night and this weekend

Francois

Henry

During this intermission I would like to point out that refreshments, T-shirts and souviner journals are available in the lobby.

You can also can also sign up to receive a personalized autographed copy of the video. You can also order a video and transcript over the internet at www.fdion.com. Visa and Mastercard accepted. Sorry, like the Olympics we do not accept American Express.

Please remember you get to keep the Ginsue as a free gift

musclecar97

lol, lol, lol....your killing me