Torquey Cars feel "slower" - perf. tidbits
#1
09-12-2006, 09:06 AM
Join Date: Jul 2005
Location: Central North Carolina
Posts: 2,105
Torquey Cars feel "slower" - perf. tidbits
This is long, but maybe worth it to real car nuts or anyone with a Supercharger.
As I reported earlier, I got my 'vette back after something like 10 weeks in the shop due to an unfortunate set of delays in parts, etc. It went in with 603 RWHP, hit the mid 600s during dyno testing and tuning, and came out with only 500 - my Procharger succumbing to a common problem with their design and twisting/warping its tensioner/idler pulley plate just enough to consistently throw the belt. Along with a reinforced plate (at least four weeks back order, they say, so I expect eight), I've ordered an upgraded intercooler which is supposed to be worth "2 lbs boost."
Anyone else with a Procharger might be interested: the bracket and intercooler are both included in the "Stage II kit" listed here.
https://www.aandacorvette.com/cart/s...p?MainCatID=18
I imagine there are similar kits for Vortech too, (I've been told there are).
I ordered this new intercooler & intake because of interesting fact #1: when the shop removed the SCr they intended to just to button up the car, put on a stock belt, and return it to me to drive it until the parts come in, with it breathing through the Procharger intake like it does when the SCr is not on boost. But they dynoed it first: , it would only produce 400 HP at the rear wheels: it was breathing "through a straw.". So they disconnected the intercoolers, etc., leaving them in place, and installed a so-so aftermarket intake that would fit. 500 RWHP. There is more there if I went to cold air intake, but I'd have to remove the intercoolers only to reinstall them in a couple of months, all for maybe 15 HP.
Anyway, as I reported earlier, SCr or not, the car drives like a dream - perfect tuning for the street now, behaving like it was when stock, but without the SCr it seemed way down on power. In fact, it didn't even seem "fast" (it felt a bit faster than the Porsche, but not power-to-weight-ratio-nearly-twice-as-good faster). So, with my son driving (faster shifts) we took it out this Sunday to the same spot we ran 0-150 in less than 14 seconds some months back and re-ran that test. 16.6 seconds. So while it's nearly 3 seconds down on what it did with the SC, (13.8) this test shows it has about 500 RWHP: that's somewhere around 565 at the flywheel: i.e., about 10% or so better than a stock C6 ZO6, which does 0-150 in 17.5 according to Car and Driver (with driver only though, I think). Incidently, it did a 0-60 of 3.5 (best ever with two on, less wheelspin at the top of first gear),
But again, it did not feel that fast when I drive it. On thinking it over, I recalled something Car and Driver said in a comparison test of small- versus big-block vettes back in the 70s: the big block was really much faster, but the small block felt faster: the small block had much less low end torque and built power in a rush as the revs increased -- power kept increasing and that felt fast. By contrast a torquey car squirts off the line hard with all that low-end grunt and keeps accelerating hard -- but the sense of power doesn't increase as it accelerates and the revs build, and thus it does not convey that same "rush" that you get with a car that builds power as it increases speed and revs, even if a bit less powerful.
Normally aspirated, my engine dynoed 500 RWHP and 508 rw torque at around 4000 RPM: equivalent to about 564 HP and 573 torque flywheel: with a very fat torque curve (I'll try to get a plot scanned and post it). With the SCr, the car had 100 extra RWHP, but almost all of that about 4500 RPM. So it felt A LOT faster because it not only did have more power, the power built in a rush.
This is interesting for several reasons. First, its fascinating that the body and its senses can be "tricked" like this: it shows the need to never trust "seat of the pants" feel and realy test everything quantitatively.
Second, it makes one appreciate the virtues of the centrifugal SCr, which builds power at the top only and thus delivers that "rush" -- making the car all that much more enjoyable.
Food for thought.
As I reported earlier, I got my 'vette back after something like 10 weeks in the shop due to an unfortunate set of delays in parts, etc. It went in with 603 RWHP, hit the mid 600s during dyno testing and tuning, and came out with only 500 - my Procharger succumbing to a common problem with their design and twisting/warping its tensioner/idler pulley plate just enough to consistently throw the belt. Along with a reinforced plate (at least four weeks back order, they say, so I expect eight), I've ordered an upgraded intercooler which is supposed to be worth "2 lbs boost."
Anyone else with a Procharger might be interested: the bracket and intercooler are both included in the "Stage II kit" listed here.
https://www.aandacorvette.com/cart/s...p?MainCatID=18
I imagine there are similar kits for Vortech too, (I've been told there are).
I ordered this new intercooler & intake because of interesting fact #1: when the shop removed the SCr they intended to just to button up the car, put on a stock belt, and return it to me to drive it until the parts come in, with it breathing through the Procharger intake like it does when the SCr is not on boost. But they dynoed it first: , it would only produce 400 HP at the rear wheels: it was breathing "through a straw.". So they disconnected the intercoolers, etc., leaving them in place, and installed a so-so aftermarket intake that would fit. 500 RWHP. There is more there if I went to cold air intake, but I'd have to remove the intercoolers only to reinstall them in a couple of months, all for maybe 15 HP.
Anyway, as I reported earlier, SCr or not, the car drives like a dream - perfect tuning for the street now, behaving like it was when stock, but without the SCr it seemed way down on power. In fact, it didn't even seem "fast" (it felt a bit faster than the Porsche, but not power-to-weight-ratio-nearly-twice-as-good faster). So, with my son driving (faster shifts) we took it out this Sunday to the same spot we ran 0-150 in less than 14 seconds some months back and re-ran that test. 16.6 seconds. So while it's nearly 3 seconds down on what it did with the SC, (13.8) this test shows it has about 500 RWHP: that's somewhere around 565 at the flywheel: i.e., about 10% or so better than a stock C6 ZO6, which does 0-150 in 17.5 according to Car and Driver (with driver only though, I think). Incidently, it did a 0-60 of 3.5 (best ever with two on, less wheelspin at the top of first gear),
But again, it did not feel that fast when I drive it. On thinking it over, I recalled something Car and Driver said in a comparison test of small- versus big-block vettes back in the 70s: the big block was really much faster, but the small block felt faster: the small block had much less low end torque and built power in a rush as the revs increased -- power kept increasing and that felt fast. By contrast a torquey car squirts off the line hard with all that low-end grunt and keeps accelerating hard -- but the sense of power doesn't increase as it accelerates and the revs build, and thus it does not convey that same "rush" that you get with a car that builds power as it increases speed and revs, even if a bit less powerful.
Normally aspirated, my engine dynoed 500 RWHP and 508 rw torque at around 4000 RPM: equivalent to about 564 HP and 573 torque flywheel: with a very fat torque curve (I'll try to get a plot scanned and post it). With the SCr, the car had 100 extra RWHP, but almost all of that about 4500 RPM. So it felt A LOT faster because it not only did have more power, the power built in a rush.
This is interesting for several reasons. First, its fascinating that the body and its senses can be "tricked" like this: it shows the need to never trust "seat of the pants" feel and realy test everything quantitatively.
Second, it makes one appreciate the virtues of the centrifugal SCr, which builds power at the top only and thus delivers that "rush" -- making the car all that much more enjoyable.
Food for thought.
#2
09-12-2006, 11:04 AM
RE: Torquey Cars feel "slower" - perf. tidbits
That was definitely an interesting find, but I thought you said you enjoyed driving your car more when you had the Maggie installed because of the power it made down low as opposed to the ProCharger taking longer to gain power?
#3
09-12-2006, 12:55 PM
Join Date: Jul 2005
Location: Central North Carolina
Posts: 2,105
RE: Torquey Cars feel "slower" - perf. tidbits
Yes, you are right. And I still consider the setup I had with the stock LS6, 1 3/4 inch headers, and the magnusen supercharger to be among the sweetest set ups I ever had. I recommend it to anyone.
Part of it is that it is fun to drive a torquey car, and that setup gave me enough of a rush: the car had 470 torque, 465 HP (both at the rear wheels) but the torque peak was up near 4900 - higher than you would expect. It built plenty of boost down low but added more up top, so it gave you a bit of a "rush" -- not as much as a centrifugal, but enough to be fun.
Mainly though, what I remember with the Maggie was the complete reliability and perfection of it. We installed it and it never gave a minute's problem in two years, and ran as sweet as stock under all conditions. It was just a delight to own as well as good to drive. I've had continuous nuisance problems with my Procharger since day one: squeaky pulleys, alignment headaches, and now, of course, my $7000 polished-aluminum P.O.S. is sitting on a bench at the shop because it was not designed well and I have to buy more parts from a different company to fix the damn thing (I'm not a happy camper here).
Part of it is that it is fun to drive a torquey car, and that setup gave me enough of a rush: the car had 470 torque, 465 HP (both at the rear wheels) but the torque peak was up near 4900 - higher than you would expect. It built plenty of boost down low but added more up top, so it gave you a bit of a "rush" -- not as much as a centrifugal, but enough to be fun.
Mainly though, what I remember with the Maggie was the complete reliability and perfection of it. We installed it and it never gave a minute's problem in two years, and ran as sweet as stock under all conditions. It was just a delight to own as well as good to drive. I've had continuous nuisance problems with my Procharger since day one: squeaky pulleys, alignment headaches, and now, of course, my $7000 polished-aluminum P.O.S. is sitting on a bench at the shop because it was not designed well and I have to buy more parts from a different company to fix the damn thing (I'm not a happy camper here).
#4
09-12-2006, 02:44 PM
RE: Torquey Cars feel "slower" - perf. tidbits
GREAT thread, Lee! I have wondered about this for many years, and your post here very eloquently outlines why. Even though our Vette is bone stock with the L98, she's got gobs of low-end torque for an ol' guy like me. Our last Mustang we had was very "pipey" in the top-end like what you describe... and you got a good "rush" over 3,500 rpm or so... but the Vette has TONS more torque... and from what I "feel", the Mustang "felt" faster, but I have NO doubt our Vette is, in actuality, a much faster car.
Great thread, my friend.
Great thread, my friend.
#5
09-12-2006, 05:51 PM
RE: Torquey Cars feel "slower" - perf. tidbits
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