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Discussion Starter #1
Just got the AP22, and have had a quick play...

Very limited by traction on the acceleration runs My Bridgestones are fairly worn.

Best 0-60 was 6.2s. 40-70 was slightly more encouraging at 3.2sec. Peak in gear acceleration recorded was 0.59G at about 40mph, which I think is fairly respectable

I did do slightly better on stopping though :

----------------------------Time-----Dist-----g Force
From 60 mph To 50 mph 0.55 s - 44 ft - 0.87 g
From 60 mph To 40 mph 1.08 s - 79 ft - 0.91 g
From 60 mph To 30 mph 1.59 s - 105 ft - 0.97 g
From 60 mph To 20 mph 2.11 s - 124 ft - 0.94 g

I didn't go to 0 as the brakes weren't fully warmed up and I didn't want to stop on a hot spot.

I actually managed a peak braking force of 1.1G on a later attempt


Car: 93 9000 CS2.3T. A lot of mods. Dynoed at 311bhp/347lbft at the flywheel.
 

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I think the figures are amazing. My feeble 205 bhp 9-3 Aero is an absolute pig to do standing starts with, but my best 0-60 (on a truly flat road) was 6.89secs, and max in-gear acceleration measured at 0.52g.

Haven't done any stopping measurements yet.

I'm pleased with these figures for a wholly unmodded car (engine & suspension).


I can see these performance meters taking off with Saabsceners - before anyone else buys one perhaps a group buy ought to be considered? Might be worth approaching Race-Technology to see if there's any potential discount? Too late for those of us who have already purchased though
 

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Hi Mark,

Quite interesting! Can't live with those acceleration figures, awesome dude.
To redeem myself, how about 60-20 in an average over seven runs of 1.95s, 1.0g, 114ft though!! (14deg C ambient)

Nick.
 

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Niiiice. I like the accellerationg figures there. That .59 g's though ... my Viggen needs some new rubber methinks. It won't even budge .54 without serious tire spin in 1st gear! As for the braking. Very nice as well. Though I think the tires were a hinderance there being so worn. I think car and driver rated the stock Viggen at 125 ft from 60 all the way down to a complete stop. So you're in the ball park with it. Which isn't bad for 1993 vs. 1999-2002!

Also, that accellerometer could have probably measured your hp pretty accurately. According to the .59 g-force in 2nd gear you were putting down to the ground 281 lb ft! (assuming the car weighed roughly 3320 lbs or so) That's still a 20% loss from the 347 lb ft at the crank on the dyno. But that's probably due to the really quick accelleration. When you're accellerating really quickly a lot of hp and torque is wasted spinning up the flywheel and wheels and transmission etc ... so 281 at the wheels sounds about dead on. Kudos!
 

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Discussion Starter #5
Originally posted by cdcarlsson:
[qb]To redeem myself, how about 60-20 in an average over seven runs of 1.95s, 1.0g, 114ft
[/qb][/b]
Chuff me Nick, that's incredible!!

What brakes have you got to better an AP 330mm set up? I don't know if /john has ever tried your brakes to the max for comparison (he has mine) but everyone who's experienced the APs on mine has been utterly gobsmacked by them.

I must admit I did have some doubts about the AP22 accuracy though, particularly the absolute speed.

When I did my runs, it didn't always register 70 in 2nd gear- despite the fact that the speedo was reading nearly 75, and I know from GPS readings that it's pretty spot on at that point. Ditto the 50-80 run I did.

The car certainly feels much quicker than the figures indicate.

A final note... I realised later that the accleration times are not my best
. I was experimenting with using a Dawes device as a max boost limiter. Peak boost on my runs was a little under 1.5 bar. Without the Dawes, I boost to about 1.65 bar. Not that that will help the lower speeds- more than likely it will make them worse. My worst ¼ mile time was after I'd taken the boost limit off and lit the tyres all the way to 60mph! (that's what an LSD and too much torque will do for you
)

Anyway, I'll try to get some more useful times in the not too distant. I'm going to forget 0-60 'cos that's not what my car is about. In gear acceleration is where is counts.
 

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Whoa! Your car may have more than 320 lb ft at the wheels then! I thought your second gear would have been somehwere near what the Viggen's was. (It'll go to about 62 before hitting the 6K rev limiter) If you can do 70-75 in 2nd that'd put the WHEEL torque much higher than I calculated before! Are you sure that wasn't just a momentary surge due to shifting out of first and into second?? If not then you've got a LOT more torque than the dyno was letting on.
Here's the math to back the figures up:

1. Convert any acc to hp: hp = weight x g-force x speed / 550

2. Convert hp at a given RPM to torque: torque = hp x 5250 / rpm

I assumed your car weighed at least 3320 with you in it, if it weighs more you have even MORE torque. I also assumed your 2nd gear went to 72 mph. Feel free to get more accurate figures and put them back into the equation to get more accurate results.

If at 6K rpms you're at 72 mph, then at 40 mph you're at 3,333 rpms.

hp = 3320 x .59 x (40 mph x 1.466 fps/mph) / 550 = 208.8 hp @ 3,333 rpm!

torque = 208.8hp x 5250 / 3333 rpm = 329 lb ft!

Remember, this method is only as accurate as the acc, rpm and speed readings. But if the speed was accurately measured, and if it consistently puts down that kind of g-force this is potentially as accurate as a dyno! Maybe it was just a jolt from the shift out of first? Does your engine rev much past 6K rpms (that could affect the approximated gear ratio).

p.s. Always remember to use the appropriate conversions. g-force and weight cancell out the need to use mass and actual accelleration. But you need to multiply mph by 1.466 to get feet per second. Other than that it's a pretty straight forward calculation to perform.
 

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Discussion Starter #7
Nope, as I careful to emphasise earlier, the peak G force I was quoting was in gear. ISTR that I actually managed a peak of about 0.7-0.8G on a change.

I don't believe the rolling road gives an accurate representation of my torque because the entire run was over in about 8 sec, and the turbo would not have been fully spooled up at lower revs.

The 2.3 FPT 9000s have verrry long gearing. 3000rpm in 2nd is just a smidge over 35mph. Rev limiter comes in at about 6300.
 

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The Viggen has a 4.05 final drive ratio dunnit? And if your car does 35 mph at 3000 that would give even more torque.
According to the accellerometer I use with the Viggen the peak acc in 2nd is only about .45-.46 g's. It's been as high as .47 during very cold weather. That's only on 12 psi of boost though. With the full pressure of 15 psi in 3rd it's gone as high as .35 during very cold weather. That equates to about 275 lb ft at the wheels for that car. Not too far off what it seems for some of the 9000's it would seem. I think most of the people who put their Viggens on the dyno were running those shoddy PFR6-H10 plugs. Might have given them lower readings that the car is capable of? Gotta love those figures from your car though Mark.
Now just imagine if you had slicks and the 4.05 final drive ratio instead! If the Viggen didn't look so neat I'd have been tempted to buy a 9000 instead. But gotta love factory smoked side markers. They make all the difference.
 

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Now just imagine if you had slicks and the 4.05 final drive ratio instead!    [/b]
BillJ tried that ratio in his aero and has now gone for a 3.8:1 ish after stipping the Diff teeth with the torque...
 

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Discussion Starter #11
Originally posted by Adrian W:
[qb]With the full pressure of 15 psi in 3rd it's gone as high as .35 during very cold weather.   [/qb][/b]
My peak boost is circa 24psi... and up at 5500 or so rpm on the rolling road where turbo lag won't be an issue, the boost is still around 18psi. On the rolling road, which I reckon does give a reasonably accurate representation of power at that rev range, that equates to circa 310hp for me. Allowing a modest 17% or so for transmission loss, that's circa 250 hp at the wheels.

So, and here we get to the heart of the matter because there's a number of us who find the results from your performance meter questionable, I've got a 9000 with the same basic engine but gas flowed and ported head, upgraded intercooler, delivery pipe, water injection, bigger injectors, custom software, yadda yadda yadda... and it's making the same as a "stock" Viggen at the wheels(and pulling more G's despite being higher geared)? I don't think so. Even before the head, delivery pipe and higher state of tune software, it was outpulling a modded Viggen on the track.

Adrian, please, do us all a favour and get your car on the rolling road to back up you claims. Without it I'm afraid your arguments just don't hold water. Don't get me wrong, I'd love it if your car were a
"freak" but as things stand it flies in the face of a lot of combined Saab tuning knowledge and experience.

Come on, give it a go... we're all waiting with baited breath
 

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I intend to get it on a rolling road. Believe me I would have done so sooner had I not lived in a dang desert. lol! It's still 85 degrees here during the day. And hey, the car accerllerates as the car accellerates. I DO have another accellerometer that isn't designed to measure hp, which I've put next to the g-tech, and while the g-techs power figures look somewhat fishy, the accelleration readings come out the same for both. I may not have 252 horsepower, but if it accellerates as it says I do, the rest is just math. I even took .01 g's off the readings because of "tilt". The only way I could NOT have the torque I claim (at least on the street) is either I'm lying , or the laws of physics and motion are lying!
I blame physics! DIE PHYSICS DIE!!
 

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I think the fundamental flaw in your calculations from g's to hp is that you are not taking gearing into account. The mechanical advantage of the gearing will give you much larger torque, in the lower gears, to the wheels. Do the same tests in a higher gear and your numbers are pretty much bound to come down.

If I am incorrect, please explain it to me, oh great physics master!
 

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Certainly. I DO take gearing into account. In fact finding the rpm you're at when you do that accelleration is very very important. I calculate the RPM at the particular speed by knowing what the max rpm is in that gear @ 6000 rpms. OR whatever the given redline. This is how gearing affects the reading, higher gear, lower rpm and consequently lower acc. Remember I found that my car put roughly 211 hp in 3rd gear at 90+ mph with greatly increased wind resistance (wind resistance to the tune of 30-40 hp). ACtually, finding hp doesn't even require rpm. Just finding torque. Remember ...

hp = weight x g-force x speed (fps) / 550

You're welcome to research this equation, but nowhere in it is rpm or gearing required to find hp. RPM and gearing do have an effect on wheel hp ... but you don't need either to find hp. If your max hp is at 5500 rpm, then in every gear when you reach 5500 rpm IRRESPECTIVE of the exact gear ratio, you will see your highest hp. This just means in lower gears you get your hp sooner, and since hp is directly linked to accelleration, you typically see your best accelleration in those gears as well. Takes a little time to understand perhaps, I've been doing that stuff for a while. Just try putting some of your own numbers into the equations. Be suprised what sorts of patterns you find sometimes.
 

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LOL It's not contradictory. True that sometimes wind can cause the apparent peak hp to drop a few hundred rpm because the hp is no longer climbing, and the wind resistance still is. But that's not the point I was trying to make. Gear ratios do not affect your actual power output. They seem to, and in a sense they affect your total torque output. But I don't want to get TOO far into torque converting by gear down.
Suffice to say shorter gears will increase the "wheel" torque, but when you're on a Dynomometer they don't actually measure "wheel" torque. They measure torque as a function of hp and rpm. Which is actually DIFFERENT than the physical torque at your wheels. If you were in a ratio in your gearbox of exactly 1:1 ... then your crank torque and wheel torque would be exactly proportional. When I estimate torque with an accellerometer I use the same technique they do on a dyno. In order to measure the physical torque on your wheels I would have to know WHEEL rpm, and not engine rpm. Anyway, point to be made here. Wind resistance does mean that at 90 mph less hp sees its way into accellerating the car than at 55 mph. BUT this has nothing at all to do with gear ratios. Remember:

hp = weight x g-force x speed (fps) / 550

Nothing in there at all about gear ratios, rpm, or even wind resistance. You don't need it to just find hp. Though knowing how much hp it takes to keep a car moving CAN give you a good estimate on the wind resistance at a certain speed. Thus allowing for a rough approximation. But it's not necessary, and certainly not contradictory.
 

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Discussion Starter #19
Originally posted by Leon (9-5 stg2):
[qb]Can't see how wind will affect BHP persoanlly.. the engine will still chuck it out    [/qb][/b]
Indeed... but it will affect the Gs measured (and thus bhp calculated).

As far as I can see the equation:

hp = weight x g-force x speed (fps) / 550

only holds true in a frictionless environement... i.e. the g force it needs to use to be correct for hp measurements is the absolute acceleration g force imparted by the engine. What an accelerometer will measure is the g force modified by external factors such as wind.
 

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Quite true MarkE ... the g-force gives you a very conservative estimate on hp. In reality what you see in g-force calculated hp is much LESS than the actual "frictionless" hp would be. Not that there is a truly frictionless environment. Might remind you the only difference between the g-force measurement and a dynomometer is lack of wind resistance. The dynomometer just measures the rate of accelleration on a drum with a calibrated rotational inertia and friction coefficient. Other than that, hp STILL = weight x g-force x speed (fps) / 550 Just with the dyno it's hp = rotational mass x rotational accellertaion x rotating speed / 550 ... still same method, just calibrating the dyno roller, instead of the, wind resistance, weight and friction coefficient of your car. *shrugs* It's all the same to me.

I also hope you haven't mistaken it for some "hokey" method that someone dreamed up for calculating horsepower. This formula is not a method to find horsepower, it is the DEFINITION of horsepower. Irrespective of any, and I mean ANY, external forces, that equation will give you the delivered horsepower to the ground. Now estimating crank horsepower, estimating power lost due to friction or wind, and getting accurate readings are not part of the equation. But the equation itself is what horsepower is in the first place.
 
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