Loss of 22.5% HP
 

Can this be right



Ok say a stock 370Z puts down 258 hp to the wheels, and its rated at 332 hp to the flywheel. Easy math says thats a 74 hp loss which is 22.5%. That seems like alot for a rear wheel drive car to lose that much through the drivetrain. Now if it were AWD then I would believe it. Is Nissan fudging there numbers HMMMMMMMMM.:shakes head:

I know when there are 90deg turns involved, there is a power loss - so, most of that is accounted for in the rear diff as it goes from the driveshaft to the rear axles.

I don't remember the percentages though - it's somewhere around 15-25%, so 22.5 isn't out of the norm, I'd think...

My bike is that way - it has a 90 for the drive shaft from the engine, and another in the final drive for about a 30% loss.

258 seems low...unless my Z had amazing numbers to begin with. My first dyno pure stock:

http://i302.photobucket.com/albums/n...est-09370Z.jpg

258 is low, dyno avg is between 270-280

My dyno numbers were the same as this...

http://i298.photobucket.com/albums/m...t/Dyno_273.jpg

1 of 3 reasons......

It is a heartbreaker dyno
the correction factors are wrong on the dyno or (the most likely)

The dyno is at a shop that is going to sell you mods and then re-dyno. They want to get a low baseline number so that $1000 pulley gets you 25 hp and you will pay another $2000 for a high flow Kuhneutson valve or a good set of high precision muffler bearings. 8-)

http://i302.photobucket.com/albums/n...est-09370Z.jpg

And the cool thing about this? Mine is a 7AT and zZSportZz is a 6MT. Shows how darn close they are. ;)

guys, different dynos read lower and higher on the same exact car. Im sorry to say but this thread was doomed before it started.

It depends on the dyno, most low low reading dynos like a mustandyne or a dyno dynamics will read around 260 for a stock Z. A normal reading dyno like a dynojet will run around 270 and a high reader like the dynapaks will run 280 stock.

This is not a rule, its just ranges. There are ringers out there.

what......urs is a 7AT.....i thought it was a 6MT all this time

The 7AT near his avatar didn't give it away? :happydance:

Nope....7AT......good thing actually since I broke my left foot back in March! :p

#4 nissan over rates thier engines :D...i heard

:iagree:

LOL
Replacement : KaleCoAuto, Hard to find automotive items!

+1. I'm going to get a baseline on a dyno-dynamics tomorrow. Yeah, it sucks that I'm not going to see DynoJet numbers, but I just want to track the improvements my intake and exhaust will provide... so no big deal. If I want some big numbers to advertise in my sig I will go all the way out to Altered and run on their DynoJet. :icon18:

Anyhow, this serves as another The370Z.com Learning Lesson (TM) that when we try to compare dyno numbers we should disclose the type of dyno used.

My :icon23: dyno reads really high.

^ +1. theDreamer just did a DD baseline at 243rwhp on a 6MT car. I know that sounds low, but (a) this is DD, which reads lower than most, and (b) even among the same mfg, every Dyno is set up a little different, and runs in different conditions, etc. Apparently EngineLogics is our local super-heartbreaker. It's kinda nice knowing that your numbers can't possibly be interpreted as inflated though :)

You know removing the a/c frees up HP.

What I am interested in, then, is how gains are going to compare across dynos. I'm going to go back after I install my Injen intakes, which Injen claims gains 15whp. Their test was on a DynoJet and the gain amounted for about a 5.3% gain with a 279whp baseline.

If I baseline at 243 whp, I wonder if I could use that 5.3% and estimate a gain of 12whp. I think there are too many variables so I doubt I can do a linear comparison but it will be interesting to see what comes of it.

Am really looking forward to your dyno with the intakes... am waiting to pull the trigger on the Injen but would like some more real world numbers.

I will post up a detailed thread. Install pics, dyno vids, and all. I should have the intakes next week and will install them over the weekend. I'm planning to drive the car for a week before a dyno just to give everything time to adjust.

I would recomend doing a baseline dyno first, then do one with mods. This is the only way to truly know what gains you are getting

That's what I'm doing. Baseline tomorrow, dyno after intakes in 2 weeks, and then again after FI CBE. :hello:

And of course the baseline dyno and subsequent dynos must be performed on the same machine. Otherwise it's totally pointless.

Gentlemen... I am not a noob. :icon18::driving:

Sigh. Different dyno's read different numbers - ESPECIALLY if a load is put onto it! A Mustang or Dyno-Dynamics dyno will generally read low. Altered Atmosphere's dyno is a Dynojet dyno, which doesnt put a load on the motor. They always read higher than others. I will put money that the OP's dyno was a dyno of the type that puts a load on the driveline.

And that would be an excellent bet. 258whp is exactly what our bone stock 370Z made on our Dyno Dynamics. :)

http://www.injectedperformance.com/h...-258whp+tq.jpg

[YOUTUBEHQ]X8iLCR-Yqo8[/YOUTUBEHQ]

Well Hell
 

So basically most of you agree that not one dyno is accurate. One thread said " A normal dyno" which to me sounds a little broad. How about this I will go to three different dyno shops and pay three times what I want to pay and take the average. I do believe that most dyno shops have to have their machines calibrated by the state of some sort to charge customers money and be considered a business.

The best thing you can do is pick a shop/dyno and stick with it for the life of the car. I did my baseline with a dyno dynamics at a certain shop and will be going whenever I feel I need to re-dyno my car after an upgrade or need a tune from them.

All dynos are accurate on their own scale, as long as they are well maintained (ours is). Even car manufacturers can't always agree on what to accurately rate engine power at. What you also have to consider is the formulas behind each dyno and how the numbers are determined. It is a fairly complicated process that takes in a scary amount of values to determine what numbers to output on the screen. As a previous poster pointed out, some dynos are load bearing; others are not. Some, like a Dynapack, measure from the hubs rather than the mounted wheels and tires.

There is no such thing as a "normal" dyno or a right vs. wrong dyno. We have our reasons for choosing a Dyno Dynamics over the other choices, but that does not mean that we feel DynoJet numbers are irrelevant. They are simply using a different scale than ours. The important thing is that you remain consistent on the brand of dyno that you go to. A DD's numbers will be comparable to just about any other DD's numbers, but directly comparing a DD result to a DynoJet gets a little more fuzzy. The only *true* way to measure horsepower output is through an engine dyno, not a chassis dyno. All we can realistically do is measure gains from our baseline on X dyno to the results on the same type of dyno.

I'm going to the dyno that gives my car the most HP! I'll feel better that way! :rofl2:

Contact some of the board members, they have some great Paint dynos, best numbers yet. ;)

Well, in *theory*, the value of a a ft/lb of torque is based on international standards. Therefore any machine reading ft/lbs of torque from the spinning wheels of a car under the same loading conditions (meaning, some standardized approximate simulation of the weight of the car and aerodynamic load), with the same (hopefully minimal) wheel-slip error on the rollers, should read the same value.

I understand, to some degree, why the situation is as it is, but I think there is a "right answer" as to how much rwhp is actually being put out of the car, and I think the dyno mfgs could be doing a better job than they are of getting their results in line.

To add to Ryan's reply...

Hub dynos, such as the DynaPack, will be more consistent from test to test than roller dynos. With roller dynos, you can have differing air pressures in the tires, the dyno monkey can strap a car down harder one day and lighter the next, etc. Hub dynos remove at least that portion of the variability. What's left is a solid drive train that should give you results well within the statistical error range of the dyno itself (0.5-1%ish range). A roller dyno can easily give you errors in the 5% range if not set up consistently.

Whatever style you choose to take a baseline on, stay with it after modding to see what gains you achieved. If it's a roller dyno, I suggest 2-3 different days (with hopefully different guys setting it up) to average out inconsistencies in setup. Yes, this obviously gets expensive on a roller dyno, but if you want solid numbers you can either do it that way or go with a hub dyno. The same thing should be done after the mods are in place to see what was gained. If you go from one style to another, you need to take another baseline. Mustang dynos are notoriously low in numbers, but that doesn't mean they're wrong, and hub dynos are typically the highest values. You cannot compare one person's Mustang dyno to another's hub dyno run and expect to compare apples to apples.

Even then, taken the same day, within the same part of the day if possible.

thanks fellas for all your input. This is why I asked the question because I really didnt believe the loss myself. I will stick with one dyno the whole way through.

I dynoed my car on a Dynojet today and the weather conditions were 90 F 29.91 Hg. I don't think they used fans. My best run was 272.17HP and 221.93 Torque. Despite the weather conditions, doesn't that seem awful low?

No. That's in the range of stock whp on a DynoJet. It's not the highest but that could definitely be a result of the conditions.

And the mere variance of different dyno's, naturally.

:tup: Word.