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Why the stigma on Saabs "from a dig"...LONG Posted by David in Tallahassee [Email]  (#970) [Profile/Gallery]
(more from David in Tallahassee) on Mon, 20 Aug 2007 16:21:35
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I have been a drag racer of ALL types of cars for over 20 years. I have made hundreds of 1/4 mile passes at my local dragstrip and, as much as I hate to admit it, I've had inumerable "street races" WITH everything and IN everything imaginable. (I agree with the "No Fear" tee-shirt that says "Racing is a life sentence without the possibility of parole.")
The launch is certainly a factor of suspension, drivetrain layout, transmission design and gearing which all contribute to weight transfer etc. but let's look at this for a moment.
The Saab NG900 has a FWD layout which means that the heavier end of the car is planting the front wheels. It has very deep gearing suitable for getting the car quickly into the revs where it can make power. Factory stock it makes peak torque at, a super low for a 4 banger turbo, 2100 RPMs with a good spread of torque across the rev range still producing 90% of it's peak torque past 5500 RPMs.
Now let's look at the much hailed 5.0 Mustang with it's front engine driving it's rear wheels all conventional-like. It makes LOTS of torque VERY low down (300 FT LBS at 2400 RPMs) but has a much lower HP peak which is at a very low RPM. (225 HP at 4200 RPMs) So, in short, a very narrow spread of tapering power. Yes it's still making 90% of it's peak torque at it's peak power, but the peaks are only separated by 1800 RPMs not 3400 RPMS. Wind it out even to 5 grand and it's totally DONE. (Stock now. Mustang guys don't flame me I am...sort of...see below...one of you.) It's ALL about the launch for a stock 5.0. The car has nothing else, at least in stock or mildly modified form. A rear drive car has to try and transfer some of the weight from it's heavy front end to get some weight on it's rear wheels for traction. Independent suspension helps plant the power and on later Stangs that's been highly beneficial but for the purpose of this discussion we are working with the hairy old 5.0.
I guess my point is this: In the end, it's all going to come down to two basic functions: driver skill and power to weight ratio. (At least in a manual trans car.) With a manual trans, there's no excuse for a "bad" launch or being no good "from a dig". Practice makes perfect. Even though the balance between a crappy launch and a good one may seem elusive, it's a matter of skill. (Jump in anywhere here JOHN WILLIAMS) I say we stop blaming the cars. Going faster than another car is all about power to weight ratio and driver skill. If you have a faster car, it's faster because it has a superior power to weight and or you are a better driver. Certainly a good launch can allow an inferior power to weight vehicle to briefly triumph over the inevitable but in most cases, unless the power to weights are nearly identical, or the race VERY short, it should be, in fact, a brief triumph.
A couple of examples from my own stable: I owned a 1991 Jaguar XJ-S V-12. For a multitude of reasons, I refused to lose the extremely heavy 72 spoke Dayton wire wheels because they were too beautiful. No matter that they KILLED the unsprung weight to the tune of an equivalent 300 LBS of weight in the car. (On top of an already portly 4000 LB curb weight.) "That's just the way the cookie crumbles" I said as I spent $10K on modifications to build a 370 HP 400+TQ 5.3 Litre V12. The car had a stock 3 speed TH400 trans with a 2.88 gear. Talk about a recipe for the "dig" blues. Try launching 4400 LBS on 235/60 Vintage Pirellis with an 1800 RPM torque convertor and 2.88 gears. Well...I did. Over and OVER! Pass after pass. My first runs netted a painful string of high 14s and low 15s. Nice strong trap speeds near or at 100 MPH kept me from shooting innocent bystanders. I tried launching "on the stall". I tried launching "at idle". I tried launching this way and that. Never was I tapping my car's 100MPH trap speed. A car with a 100 MPH trap with the right launch has a power to weight ratio good for 13s. Gearing can get in the way too but for the most part, any trap over 100 MPH is a 13 second timeslip waiting for a driver to happen. Well, sad but true, I never hit the 13s. But one night while practicing at the old Bradenton Motorsports Park, I hit the "near 13s" jackpot. I knew it was different before I hit the 60' mark. It just "felt" right. BOOM! I ran a 14.2 at 100 MPH! The difference: a 2.1 short time instead of a 2.3-2.4. I picked up my timeslip and thought, "I wonder what I did. Can I repeat it?" Well with a little more practice it became repeatable and then I was in the zone! Now, mind you, I had made DOZENS of high 14 and low 15 passes looking for "the zone" to no avail. That's just the way it works.
I had a 1990 5.0 Mustang back in the day. With stock size tires, it spun hopelessly, at the strip or on the street. It was modified with a long list of bolt-ons including a 100 shot NOS kit. With larger than stock, sticky tires it would turn 2 flat short times with a good burnout and post low to mid 13 timeslips around 105 MPH. On street tires, with 2.3+ short times, it ran low 14s at 103 MPH VERY INconsistently. (It did post one 13.9 without the NOS at 98 MPH with a 1.98 short time which I wanted to frame because I was so proud.)
Here are some numbers for you math guys:
1996 Saab 900 SET
185 HP at 5500
194 FT LBS at 2100
Curb Weight: 3050 LBS
Power to weight: 1:16.46
1990 For Mustang GT
225 HP at 4200
300 FT LBS at 2400
Curb Weight: 3350 LBS
Power to weight: 1:14.88
Based on the above numbers, a 900 would need approximately 205 HP to match power to weight "wits" with a 5.0. Obviously the 900 lags in the torque department to the tune of more than 100 FT LBS. The question is, if his torque has him spinning the tires and your torque has you wishing you had his torque the result may not be as different as one would think. Take a look at my 5.0 times above. When I ran on street tires, I had a heck of a time getting it to hook and that was at a dragstrip with VHT on the line. On the street it was pedaling city.
A perfect "street" launch is a fantasy only to be enjoyed by AWD cars or cars with large drag radials and lots of suspension work. OR...guys who KNOW their cars and how to drive them. (Which CAN be us!!)
I most recently had a 1999 Pontiac Trans Am which ran mid 11s at over 122 MPH EXACTLY the way I drove it on the steet. Problem is, with cold tires and a street launch there was no way it was going to run as fast as it did at the track. Was it fast? Heck yeah! Did I win on the street? Yes! Was it great "from a dig"? NO! NO! NO! It took great skill to stay in my lane and get nearly 500whp to the ground. On the upside, I almost always ran down what I was chasing even if they were able to get me "from a dig".
I guess what I'm saying is, Saabs make a LOT of power over a VERY broad range. They ARE fast cars from a roll, on the highway AND (yes I'm saying it.) from a dig.
It's a matter of balance...
Wow...I feel SOOOOO much better!
D-
, Mon, 20 Aug 2007 16:21:35 <-- Viewing This Message, Wed, 29 Aug 2007 19:04:40, Fri, 31 Aug 2007 20:31:22, Mon, 20 Aug 2007 17:23:17, Mon, 20 Aug 2007 17:59:58, Mon, 27 Aug 2007 13:13:03, Thu, 23 Aug 2007 15:57:05
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