Dyno Day, 620whp

[Daijoubu]

A bunch of my BMW friends rented a dyno, so I thought I would tag along and put my car on the rollers if they had time. As you can tell, 620whp and 595ftlb of torque is pretty healthy for a car advertised at 668hp. I don't really think it was a happy dyno either, because a couple of the BWM guys were a little disappointed with their pulls. They were all modified though, so hard to compare. I tried to find someone with a stock Hellcat to come dyno the same day to compare, but to no avail.

 

[jbawden]

Solid baseline! Seems as though GM might be pulling a page from the BMW playbook and underrating these a bit.

 

[668LT4]

Solid baseline! Seems as though GM might be pulling a page from the BMW playbook and underrating these a bit.

BMW is off the charts. At least for the S58. I recall a dyno report on the manual M3 or 4 that had almost the entire listed HP at the wheels, and even more torque than listed. Still good numbers by the LT4 compared to how it is rated.

 

[565565]

The real question is, what did that X1 make?

 

[WONT TAP]

Great starting point! Do you plan to turn up the wick?

 

[jvp]

Solid baseline! Seems as though GM might be pulling a page from the BMW playbook and underrating these a bit.

Let's be clear: there's no underrating of GM engines since they started SAE ratings back during the LS7 days. Chassis dynos are not good ways to calculate your flywheel HP. Never have been, never will be. Their only proper use is to baseline the car, then do mods, and get another readout.

The engine is making 668HP +/- a very small percentage. Otherwise they can't claim SAE ratings.

 

[Exia]

M

BMW is off the charts. At least for the S58. I recall a dyno report on the manual M3 or 4 that had almost the entire listed HP at the wheels, and even more torque than listed. Still good numbers by the LT4 compared to how it is rated.

My S58 was awesome, I very much doubted it was putting out the 503hp they advertised. More like 550 at least.

It got great fuel economy as well, BMW can sure make a straight 6.

 

[Snowwolfe]

Let's be clear: there's no underrating of GM engines since they started SAE ratings back during the LS7 days. Chassis dynos are not good ways to calculate your flywheel HP. Never have been, never will be. Their only proper use is to baseline the car, then do mods, and get another readout.

The engine is making 668HP +/- a very small percentage. Otherwise they can't claim SAE ratings.

Can't they claim SAE ratings if they exceed them?

 

[MatthewAMEL]

Can't they claim SAE ratings if they exceed them?

No. If the number is stated in SAE, it must be that number. Also, it's required that a certain number of engines are randomly sampled during the production to ensure compliance.


In 2005, the SAE introduced "SAE Certified Power" with SAE J2723.[36] To attain certification the test must follow the SAE standard in question, take place in an ISO 9000/9002 certified facility and be witnessed by an SAE approved third party.

A few manufacturers such as Honda and Toyota switched to the new ratings immediately.[37] The rating for Toyota's Camry 3.0 L 1MZ-FE V6 fell from 210 to 190 hp (160 to 140 kW).[37] The company's Lexus ES 330 and Camry SE V6 (3.3 L V6) were previously rated at 225 hp (168 kW) but the ES 330 dropped to 218 hp (163 kW) while the Camry declined to 210 hp (160 kW). The first engine certified under the new program was the 7.0 L LS7 used in the 2006 Chevrolet Corvette Z06. Certified power rose slightly from 500 to 505 hp (373 to 377 kW).

While Toyota and Honda are retesting their entire vehicle lineups, other automakers generally are retesting only those with updated powertrains.[37] For example, the 2006 Ford Five Hundred is rated at 203 horsepower (151 kW), the same as that of 2005 model. However, the 2006 rating does not reflect the new SAE testing procedure, as Ford is not going to incur the extra expense of retesting its existing engines.[37] Over time, most automakers are expected to comply with the new guidelines.

SAE tightened its horsepower rules to eliminate the opportunity for engine manufacturers to manipulate factors affecting performance such as how much oil was in the crankcase, engine control system calibration, and whether an engine was tested with high octane fuel. In some cases, such can add up to a change in horsepower ratings.

 

[quikag]

Good numbers and I agree it technically needs to be right around 668hp flywheel to be SAE rated.

What I'm happy about is my 128mph trap speed earlier this year at Ennis, TX at the 1/4 mile strip there. A bone stock, stock tire pressures, six-speed manual with CC brakes, sunroof, etc. that weighs 4,400+lbs with me in it and over half a tank means the engine is healthy. Entry #14 on right of timeslip.

P.S. I suck at drag racing. I'm a road course guy and get to the 1/4 mile strip maybe once every several years. It's fun, so I may try to do it a bit more often though in the future.

 

[Ergoc5]

@quikag was that with no lift shifting?

 

[jbawden]

Fair point on SAE. I actually found an earlier edit (not current) version of the SAE J1349 standard and read through it. There is a section that describes how to determine the certified results and it's average of the runs, but the published number needs to occur at least twice in the series. It's interesting to see how comprehensive the testing and reporting standard is.

With that said, it is interesting how BMW in particular seems to outperform expectations of the published numbers. Also, collective pool dyno data seems to support underrating which perpetuates this myth. While the intent of the J1349 is to prevent overrating, it would seem to eliminate underrating simultaneously. At least in the edit I read, I didn't see anything about period sampling of production engines.

 

[quikag]

@quikag was that with no lift shifting?

No, and no launch control either. Just quick, decisive shifts between gears. Been banging gears since I was 15 with a learner's permit (45 now). I can't trigger my brain consistently enough to not do a momentary throttle lift between shifts.

I did practice it at Spring Mountain earlier this month with their 5BW six-speed cars, but couldn't get very comfortable with no-lift shift. It did work quite nicely though, so maybe just need to practice more. It's very well developed.

 

[NightBlueTTS]

No, and no launch control either. Just quick, decisive shifts between gears. Been banging gears since I was 15 with a learner's permit (45 now). I can't trigger my brain consistently enough to not do a momentary throttle lift between shifts.

I did practice it at Spring Mountain earlier this month with their 5BW six-speed cars, but couldn't get very comfortable with no-lift shift. It did work quite nicely though, so maybe just need to practice more. It's very well developed.

I was in the same boat; I never got comfortable with it on my c7 z06. But I forced myself to keep practicing on the 5BW, and I am now a convert! The shifts are just soooo good and sound so nice. Worth it just for the sound

 

[Exia]

Fair point on SAE. I actually found an earlier edit (not current) version of the SAE J1349 standard and read through it. There is a section that describes how to determine the certified results and it's average of the runs, but the published number needs to occur at least twice in the series. It's interesting to see how comprehensive the testing and reporting standard is.

With that said, it is interesting how BMW in particular seems to outperform expectations of the published numbers. Also, collective pool dyno data seems to support underrating which perpetuates this myth. While the intent of the J1349 is to prevent overrating, it would seem to eliminate underrating simultaneously. At least in the edit I read, I didn't see anything about period sampling of production engines.

This a German thing, but McLaren also does it. Why? Because they know that advertised horsepower the way everyone else does it only guarantee's that in ideal conditions. They want to advertise their horsepower in the worst possible situation so that you are guaranteed that number even if you were at the bottom of the ocean or on top of Mount Everest. This is why they are underrated, because in the worst possible situation you would get their advertised horsepower but in ideal conditions you get much more.

Basically they want to ensure nobody will complain about what they've purchased and they don't want owners to say the car has 600hp when in adverse conditions it produces less and they get flak for it.

I believe they also do not do SAE but they've done this long enough that everyone knows the numbers these manufacturers give are in reality much higher.

Its the same with their 0-60 times, they are incredibly conservative because they don't want to advertise a number that an owner can't achieve unless they went a drag strip. They want you to achieve that number easily, because the product you bought should perform as advertised no matter what.

Its basically under promise and over deliver and it works.

 

[burn813]

View attachment 15504
View attachment 15503
View attachment 15502A bunch of my BMW friends rented a dyno, so I thought I would tag along and put my car on the rollers if they had time. As you can tell, 620whp and 595ftlb of torque is pretty healthy for a car advertised at 668hp. I don't really think it was a happy dyno either, because a couple of the BWM guys were a little disappointed with their pulls. They were all modified though, so hard to compare. I tried to find someone with a stock Hellcat to come dyno the same day to compare, but to no avail.

@Daijoubu I made 621hp and 598tq on a hub dyno, so I would not think that the dyno you were on is "happy" it seems pretty on par with what I have seen for manual bw5's stock

 

[Daijoubu]

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Didn't realize they posted this until now. First pull, the guy actually let off right after the hit, and I thought something was up. He told me later, "I was not expecting that!!!"