I'm betting that downshifts observations are correct and the car is only around 270HP so your loss is only 12.5%. Technically right on the money.

Jeff

 

Only 12.5% drivetrain loss is unheard of....I will stick by my claim that the Z makes the power that is advertised.
I made 243rwhp which is only 15% drivetrain loss...still a low loss for a RWD car.

17%-18% loss for a manual tranny car is pretty normal...and the AVERAGE Z dyno's around low to mid 230s...sounds right to me...

 

wait, you dynoed at 240 with all the mods that you have in your sig? something can't be right.

I'll let you know my tq figures when i get home, off the top of my head i can't remember.

 

So........ your saying that a chassis dyno is more accurate than an engine dyno???????????

Can you qualify this?

Jeff

 

Say BJ, I'm curious. If you can say, how much hp does your race car produce?

 

Did I say that?? Because I don't remember saying that. Find an engine dyno of a STOCK Z's motor and I will say that it is a better indicator of actual power. The problem is...you won't find one.

Based on what people here are saying a chassis dyno is completely useless which I disagree with. You can take a LARGE pool of numbers from many different chassis dyno's (since so many people use them) and the avearge will lessen the margin of error a great deal.

That is how I qualify my previous statement.

Furthermore...use a mathmatical HP calculator for 1/4 mile time and trap...punch in a Z's weight and 287hp and you get right around low 100mph trap speed...ironically just about exactly what most Z's are running.

I don't see any evidence that the Z is overrated...

 

Dude read the thread. downshift has confirmed 268-270hp on an ENGINE dyno. I have seen three. So now that makes four other VQ motors that have ENGINE dynos within 2% of downshifts claims thus fully backing up his claims.

If it makes you feel better to pad the numbers to your liking by all means go for it. The thing is you can perform all the mathematics, 1/4 mile, & hoodoo voodoo BS you want on the numbers based on chassis dynos but facts is facts.

I know people want feel good about their HP #s but it is time to live in reality. We got what we got from Nissan AND NO MORE.

Like downshift says there may be 1 in 1000 or 10000 or more motors that actually put out the rated 287 hp but that is all Nissan needs by law to advertise that claim.

This situation is no different than what the audio industry did years ago and still does to some extent today. The audio industry got away for years advertising rated RMS power based on a single bench test with hand picked components into resistor. Advertised power ratings were always substantially less from the same product coming off an assembly line hooked up under real world applications.

People are naive if they believe HP ratings on cars are real. Advertised HP is there to sell cars and give the consumer a base line NOT gospel. Even all of the engine dynos are not exactly the same.

Jeff

 

SHOW ME AN ENGINE DYNO OF A VQ35DE PLEASE.

Dwnshift never said that they got a STOCK VQ motor on an engine dyno...simply that they have had their RACE motor on an engine dyno. Read...it's very useful.

Furthermore, you know what...screw it...my car has exceeded all my expectations power wise on the road coures, drag strip and street. Plus I have some pretty good dyno numbers. That to me is much more important that how much ACTUAL power my motor would make on an engine dyno.

Besides...hp sells cars...a good torque curve wins races.

I'm done arguing. I've show my FACTS...now where are yours?

 

Except for the flywheel.

And I know mine is behind becuase another Z on the same day dynoed at 248 with just a Japtrix y-pipe and mid pipe Compared to that one I was expecting around 250 as I had the intake. I am tempted to try the TS ECU.

 

BriGuyMax: "mathmatical HP calculator for 1/4 mile time and trap...etc" Can you explain more about calculating hp this way.

 

No, because timing chain loss would be accounted for in crank HP. In reality, the engine itself experiences like 50% loss before even getting to the crank.

That said, my MR2 Spyder was chain driven had had a ridiculously low drivetrain loss. It has more to do with mass of transmission, drive shafts, diffs, and axles.

 

go to www.google.com and search "1/4 mile calculator"

 

I second that. I believe Nissan is over rating the car. I take my hat off to Mazda fo admitting their mistake and doing what it can to compensate these effected. I expect the same from Nissan. I like the car, but can't help feeling disapointed. When I purchase something, I expect to get at least what is promissed. Why should I have to spend $2k to get what was supposed to already be there.

 

Well, first off how many dynos were done in 5th gear, to get the lowest drive train losses, the car has to be in 1:1 in the transmission. I see many posts that they dyno'd in 4th because 5th was too fast. 2nd as some one on this post said, the dyno's are not that accurate on back to back runs. Within 5-10 hp, same car same everything. Also what TIRE pressure are you running on the dyno, I would love to see some make 4 or 5 runs going from say 20 PSI in the drive tires to the Max COLD allowed pressure allowed by the sidewall and see how much difference that makes on the HP produced. Also the VQ seems to take quite a while to fully break in and that might account for some of the differences in stock cars.

 

Lets see...you're disappointed yet a 350Z will keep up with a $70K+ Porsche 911 Carrera (297hp version weighs near the same as the Z) in any measure of acceleration. I guess Porsche overrated the Carrera in HP too...

Comparing the Z to the RX-8 is outragous....the RX-8 has underperformed for it's rated HP and weight...the Z HASN'T...

 

Boo hoo.

 

A Z will not keep up with a Carrera. Most magazines can only squeeze 5.8 0-60 out of the Z. Yes i'm sure someone knows someone who did it faster, but to be consistent while comparing the acceleration times of different vehicles, you have to use the same source for all of them. 5.8 seconds is equal to the new 6-speed accord, WRX, and a SRT-4 neon. All of these cars are rated for far less horsepower, while weighting about the same. I'm not comparing the RX-8 weight/horsepower to the Z. I'm listing it as an example of over rating. It is my opinion, but I believe the Z underperformed for a 287 hp car.

 

But if you were on 2 different dynos on 2 different days, it bears little resembleance to one another. Some read high some read low, some eople get the car that just won't die and runs insane number, some people's will let go in 100% stock form.

As for the 0-60 numbers, let's try to compare apples to apples here. The Z weighs more than any WRX or SRT4, and is geared differently as well....gearing has everything to do with the 0-60 numbers we get. A WRX runs a 3.9 final drive, a Z (with LSD) runs a 3.357 - put a 3.9 in a Z and watch 0-60 absolutely plummet......

I am sorry, but the car runs exactly the numbers it should quite frankly. Typical tuning mentality always factors drivetrain loss for most cars at around 20% give or take. Accounting for some differences from the factory of a reasonable 0%-5% power diferences (which again are 100% normal depending on the type of gas used, break in, type of oil used, wheels tires, etc etc etc.), i becomes clear that a car that weighs what the Z weighs, can reasonably be expected to run a high 5 second 0-60 and a low 14 second 1/4 mile give its gearing, weight and power. On a dyno, I would expect a range from around 220's on the low side, to 230's on the high side. most stock cars dynoed in exactly that range..ony a few exceptiosn were high or lower. such higher or lower readings can be explained a number of ways - from improper setup of the dyno, larger wheels and tires than stock, weather, and a myriad of other factors. The car has shown itself to be consistent; it's the typical intenet mentality to make a mountain out of a molehill though.

 

0-60 times??? I didn't know we were magazine racing here.

A friend of mine has a 2001 Carrera 2 6-speed and we are dead even from ANY speed...BTW 6-speed Carreras (297hp version) run low 14s to high 13s @99-102mph...right in the range of a stock Z.

Futhermore the 6 speed accord, WRX and SRT-4 (which weighs 300lbs less than a Z and is underrated) all trap lower than a 350Z in the 1/4 mile. 1/4 mile trap is a MUCH better indicator of horsepower than 0-60time.

 

It's glaringly obvious that there is too much variation in all our "dyno" tests to establish the exact drivetrain loss and, thus, verify the factory's claim with mathematical precision. The only thing more plentiful here than the hp numbers is the opinions. A little bit of dyno testing -- like a little bit of knowledge -- is a dangerous thing. Variation is normal.

When I had my SVT Cobra, the forums were filled with commentary and 'signatures' demonstrating that variation is the rule.

Despite ideas like this:

"Like downshift says there may be 1 in 1000 or 10000 or more motors that actually put out the rated 287 hp but that is all Nissan needs by law to advertise that claim."

-- there is no conspiracy.

As previously stated, front-drive has less loss than rear (if you are intent on getting bummed, the new Mini has a paltry 7% loss). Considering all the variables, I believe dyno numbers aren't even as valuable for bragging-rights as 0-60 times, which I consider practically useless.