SOTP Feel - How much horsepower does it take?
07-11-2010, 12:23 PM
#21
Race Director
C4 tech has sure changed......back in the old days the mods would have locked or moved this to General........
The ac compressor may be installed for the factory rating but its not running....
As for the OP...butt dyno is inherently flawed and is more apt to notice low end torque changes than RWHP ....with a wide powerband and shifts at 7000rpm the car may feel slower while actually being faster than when the power falls off at 5K and one is rowing threw the gears.... the L98 torque monster myth is a great case in point. Even LTX guys fall for this, on another site I frequent ....folks often talk about riding in a LSX car and saying how much slower it feels than their stock LTX car, since the LSX doesn't have the LTX's torque..... (another bs statement)
JMHO BUTT DYNO = BS when it comes to HP
As already stated, New rear gearing will throw your Butt Dyno for a loop with zero change in horsepower.
Mike
As for the OP...butt dyno is inherently flawed and is more apt to notice low end torque changes than RWHP ....with a wide powerband and shifts at 7000rpm the car may feel slower while actually being faster than when the power falls off at 5K and one is rowing threw the gears.... the L98 torque monster myth is a great case in point. Even LTX guys fall for this, on another site I frequent ....folks often talk about riding in a LSX car and saying how much slower it feels than their stock LTX car, since the LSX doesn't have the LTX's torque..... (another bs statement)
JMHO BUTT DYNO = BS when it comes to HP
As already stated, New rear gearing will throw your Butt Dyno for a loop with zero change in horsepower.
Mike
Last edited by aboatguy; 07-11-2010 at 12:36 PM.
07-11-2010, 01:01 PM
#22
Melting Slicks
It depends on how much power the car is making. A friend of mine has a turbo charged LSX Camaro. It made 920 RWHP on it's last dyno trip. In his car, you can't feel a 100 HP change.
In a stock-ish HP C4, I would think 15 RWHP or more would be necessary in order to really feel it.
The placebo effect is also pretty powerful when it comes to how the acceleration of a car feels. I've felt the difference after an oil change, or two coats of wax, even though the car was obviously no faster after those things.
I did heads/cam on a 91 Fox body awhile back. It felt faster, but not tremendously so. It picked up about 1.5 seconds in the quarter mile though, which is signifcant (IMO). Later, I put cut-outs on it. The owner swore that the car picked up another full second, maybe more. It felt so much faster it was ridiculous. At the track, the car was no faster. It picked up nothing. The environment that you are in (much louder with the cutouts open in this case) affects the feel of the car as well.
In a stock-ish HP C4, I would think 15 RWHP or more would be necessary in order to really feel it.
The placebo effect is also pretty powerful when it comes to how the acceleration of a car feels. I've felt the difference after an oil change, or two coats of wax, even though the car was obviously no faster after those things.
I did heads/cam on a 91 Fox body awhile back. It felt faster, but not tremendously so. It picked up about 1.5 seconds in the quarter mile though, which is signifcant (IMO). Later, I put cut-outs on it. The owner swore that the car picked up another full second, maybe more. It felt so much faster it was ridiculous. At the track, the car was no faster. It picked up nothing. The environment that you are in (much louder with the cutouts open in this case) affects the feel of the car as well.
07-11-2010, 01:32 PM
#23
Safety Car
Another thought is weight... You can tell a difference in acceleration with a full gas tank and passenger compared to a 1/4 filled tank and no passenger...
07-12-2010, 11:51 AM
#24
Team Owner
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A 200lb passenger would be roughly 5% additional curb weight, so assuming that saps 5% of the hp, that would translate to 15hp?
07-12-2010, 01:15 PM
#25
Rob
07-12-2010, 02:03 PM
#26
Safety Car
There is a definite difference between a full tank of gas and passenger compared to no passenger and 1/4 tank!
They should make one of those warning stickers for the passenger sun visor:
"Fat chicks cause loss of 20rwhp, skinny chicks ONLY"
They should make one of those warning stickers for the passenger sun visor:
"Fat chicks cause loss of 20rwhp, skinny chicks ONLY"
07-13-2010, 08:17 AM
#27
Drifting
07-13-2010, 11:58 AM
#28
Race Director
With a gear change, there is a difference in torque multiplication getting to the ground. Think of it like the difference between starting in 1st vs 2nd. That's not a false difference.
07-13-2010, 02:17 PM
#29
Safety Car
07-13-2010, 02:53 PM
#30
Racer
Thread Starter
Thanks
Thanks for all the replies, I didn't expect this many responses. After reading all your posts I see there are other factors to consider. The butt dyno doesn't necessarily indicate increased horsepower and vice versa. So I suppose if someone just wanted to FEEL faster around town gears would be a good way to go (I also like the idea of applying a "no fat chicks sticker"). I don't have any goals in mind, I was just curious what your experience has been.
Thanks!
Ron
Thanks!
Ron
07-13-2010, 07:24 PM
#31
Race Director
However, my statement was no change in HORSEPOWER...along with the OPs question about HORSEPOWER~~
Mike
07-13-2010, 07:41 PM
#32
Team Owner
Pro Mechanic
07-13-2010, 09:22 PM
#33
07-14-2010, 12:38 AM
#34
Team Owner
Pro Mechanic
I know how it works. FYI, above 5252 if the tq "band" goes up, so does hp -they [still] have a [mathematical] relationship.
However, you could do mods that only increase high end breathing (such as certain cams and exhaust among others) and only increase tq (and hp) above the original hp peak. The SENSATION would be about the same; the engine wouldn't PULL any harder...just longer. It may make 25 more hp...but you won't feel it in the SOTP. Witness the L98 vs. LT1 endless comparo's.
However, you could do mods that only increase high end breathing (such as certain cams and exhaust among others) and only increase tq (and hp) above the original hp peak. The SENSATION would be about the same; the engine wouldn't PULL any harder...just longer. It may make 25 more hp...but you won't feel it in the SOTP. Witness the L98 vs. LT1 endless comparo's.
07-14-2010, 01:13 AM
#35
I know how it works. FYI, above 5252 if the tq "band" goes up, so does hp -they [still] have a [mathematical] relationship.
However, you could do mods that only increase high end breathing (such as certain cams and exhaust among others) and only increase tq (and hp) above the original hp peak. The SENSATION would be about the same; the engine wouldn't PULL any harder...just longer. It may make 25 more hp...but you won't feel it in the SOTP. Witness the L98 vs. LT1 endless comparo's.
However, you could do mods that only increase high end breathing (such as certain cams and exhaust among others) and only increase tq (and hp) above the original hp peak. The SENSATION would be about the same; the engine wouldn't PULL any harder...just longer. It may make 25 more hp...but you won't feel it in the SOTP. Witness the L98 vs. LT1 endless comparo's.
discounting such wonders as variable lift/duration cams, dual runner intake manifolds, or forced induction, a motor is designed to run best at a set rpm within it's power band, and all other rpms either side of that peak output are compromises in design, such as the L98's lower peak power point which allows for a stronger off idle characteristic vs the LT1's ability to spin quicker to it's redline .
rob
07-14-2010, 09:29 PM
#36
Drifting
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A lot of mods add 2-5 or a little more HP which can be measured on the dyno or track slip. But I'm curious how much horsepower does it take before you can feel it with the ol buttometer? I've done small things like catback and tossed the frisbee and don't know if I feel the difference or imagine the difference.
Ron
Ron
