Dyno graphs vs. felt power

[92saturnsl2]

Shortly after I bought my used Regal Tour-X, I purchased the Trifecta canned tune which claims to add ~40 hp / 40 tq at the wheels. The dyno sheet is attached, and for clarity, I removed the stock graph.

I compare this to a vehicle I used to own (sedan) that I had custom tuned at a shop after installing some very inexpensive mods. Both weigh within 100lb of each other, and in my experience, within 1-2 mpg of each other.

I know there's a hundred variables like gear ratios and such, but for fun's sake the Tour-X is AWD and an 8-speed transmission, the latter dyno graph is an older (early 00's) FWD with a 4-speed auto.

Which would be faster? Bonus to whoever can guess the powertrain of the older car.

 

[ctechbob]

The older car looks like it might be one of the supercharged 3.8 GM's that were available around that time. Grand Prix?

 

[SubieRubyRoo]

The older car looks like it might be one of the supercharged 3.8 GM's that were available around that time. Grand Prix?

Too much torque… 345 ft-lbs and 242HP. If it wasn’t a Buick that would be a stock Syclone or Typhoon power curve… so I’m going with a Regal T-Type with 3.8 turbo

 

[SubieRubyRoo]

Shortly after I bought my used Regal Tour-X, I purchased the Trifecta canned tune which claims to add ~40 hp / 40 tq at the wheels. The dyno sheet is attached, and for clarity, I removed the stock graph.

I compare this to a vehicle I used to own (sedan) that I had custom tuned at a shop after installing some very inexpensive mods. Both weigh within 100lb of each other, and in my experience, within 1-2 mpg of each other.

I know there's a hundred variables like gear ratios and such, but for fun's sake the Tour-X is AWD and an 8-speed transmission, the latter dyno graph is an older (early 00's) FWD with a 4-speed auto.

Which would be faster? Bonus to whoever can guess the powertrain of the older car.

The one with higher torque should be quicker thru the 1/4, but at a lower trap speed IMO.

 

[clinebarger]

Thinking Supercharged Buick 3800 also....What else could put down torque like that in a early 2000's FWD?

 

[SubieRubyRoo]

Thinking Supercharged Buick 3800 also....What else could put down torque like that in a early 2000's FWD?

Yeah I missed the FWD comment in there… has to be 3.8 Super, but 345lb-ft is pretty stout for that!

 

[ctechbob]

"I compare this to a vehicle I used to own (sedan) that I had custom tuned at a shop after installing some very inexpensive mods. Both weigh within 100lb of each other, and in my experience, within 1-2 mpg of each other."

Inexpensive mod - smaller pulley. That should get you a big low-end bump and start running out of steam quicker.

 

[UG_Passat]

Older cars, despite the big numbers they may pull on the dyno, tend to be slower than today's cars. So, the Haldex AWD car my pick for the faster accelerating car.

An early 2000's Pontiac Bonneville SSEi with the L67 motor, gets the 0-60 in 7.7 seconds. That's bordering on slow by today's standards.

A stock TourX AWD already does the deed in 6.3 seconds.

 

[Fish Fry]

Felt power is mostly in the torque numbers, not HP.

 

[SubieRubyRoo]

Felt power is mostly in the torque numbers, not HP.

Americans buy HP but drive torque, if that makes sense. People want a “fast” car so we have HP wars even though peak HP is rarely the most satisfying to drive.

I’d take 90% of 500 ft-lbs torque from 2000-6000 long before I’d ever take 500HP peak from an N/A engine like the LS7.

 

[Skippy722]

Americans buy HP but drive torque, if that makes sense. People want a “fast” car so we have HP wars even though peak HP is rarely the most satisfying to drive.

I’d take 90% of 500 ft-lbs torque from 2000-6000 long before I’d ever take 500HP peak from an N/A engine like the LS7.

Yep. I read a thing that when the guys at SRT were developing the 6.4 HEMI they found in testing that while it made great peak power it didn’t “feel” as powerful as the numbers were showing, so they redesigned the intake (or rather took inspiration from the short/long runner intake in the trucks) which lowered peak HP a bit but really helped the low end torque.

That Buick with the 8 speed should be faster than what I also assume is a supercharged 3800. When Dodge added the 8 speeds to the Grand Cherokee/Durango twins in 2014 V8 models dropped about 1 second 0-60 and 1/4 despite making identical HP and torque and going from a 3.45:1 axle to a 3.09.

 

[Trav]

3800 FWD cars can be really quick with a little (a lot in this one) of trickery, not bad for 3800 grocery getter. Notice how the GMPP Torsen diff hooks up.

 

[MattPersman]

That’s a pretty mild looking tune for a 2.0 turbo car unless they are aggressive from GM stock

 

[92saturnsl2]

Older cars, despite the big numbers they may pull on the dyno, tend to be slower than today's cars. So, the Haldex AWD car my pick for the faster accelerating car.

An early 2000's Pontiac Bonneville SSEi with the L67 motor, gets the 0-60 in 7.7 seconds. That's bordering on slow by today's standards.

A stock TourX AWD already does the deed in 6.3 seconds.

I shouldn't have made it so easy by mentioning FWD, but most guessed correctly. The mystery car in question is a 2000 Bonneville SSEi w/ L67 3.8L.

The Bonneville was a normal L67 with these mods when I had it dyno tuned: 1.9 ratio rocker arms, 3.3" pulley, E-bay stainless tube headers, high flow cat with Flowmaster super 44 mufflers (OEM exhaust otherwise). When they were dyno tuning it, they determined my knock retard (which I knew was excessive from my own scanning) was from a faulty fuel pump and replaced it with a Walbro high flow unit. Total cost of mods, I'd be surprised if it surpassed $1K.

The Buick is seriously handicapped by some electronic wizardry which I'm convinced limits torque in the first couple gears, even with the Trifecta tune. As such, it can't really take advantage of AWD in a 0-60 or stoplight race. Despite the Bonneville being seriously traction handicapped where it would roast tires well into 2nd gear (if you weren't careful), it sure felt a LOT faster from a stop. Even from a 20-70mph roll, I don't think the Buick could keep up.

(Bonneville video: )

These two cars have comparable weight, wheel horsepower (if you trust the Trifecta tune dyno graph)-- the differing factor is that torque comes at wildly different places between the two. But given the advertised power specs with the Trifecta tune on my current car, I can't help but be disappointed in its off the line performance, especially given it has an 8-speed which should keep it in the prime powerband (where torque is less important) once you hit 10-15mph or so. Rather, it spins up to 6K RPM or so in the first couple gears like it's a N/A car. Don't take this as complaining, I didn't buy a racecar nor did I want one, but I believe published hp/tq specs on newer cars are likely valid only under certain conditions because of all the computer control.

All that said, mash the throttle at 45mph and the Buick is a whole different animal (especially with the tune) and I'm convinced it would dust the Pontiac hands down at higher speeds. 100mph+ comes in a hurry and it drives better than the Pontiac ever could.

 

[Cujet]

After a lifetime of tuning turbocharged engines, I despise holding boost at a set level, but instead like to manage boost as RPM's increase. Given properly sized components, I would much rather tune for as flat torque level as possible, with the avoidance of sudden boost onset, which is generally peak torque, and the inevitable torque decline as RPM's increase.

For the few that have their vehicles tuned this way, they sure are fun to drive, as each gear pulls hard to redline.