Loss of 22.5% HP

tooohip · 08-14-2009, 03:10 PM

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

theDreamer · 08-14-2009, 03:12 PM

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

wstar · 08-14-2009, 04:02 PM

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.

Hi-TecDesigns · 08-14-2009, 05:50 PM

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.

kannibul · 08-15-2009, 10:34 AM

Quote:

Originally Posted by CBRich

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

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

lando76 · 08-15-2009, 01:27 PM

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.

tbss370z · 08-21-2009, 08:02 PM

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?

m4a1mustang · 08-21-2009, 09:26 PM

Quote:

Originally Posted by tbss370z

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.

MightyBobo · 08-22-2009, 12:02 AM

Quote:

Originally Posted by m4a1mustang

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.

DooDooBrown · 08-22-2009, 09:22 AM

Quote:

Originally Posted by Island_370

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-)

Word.

tbss370z · 08-22-2009, 09:54 PM

What gear should be used when dyno testing? Is there a formula that you can use to adjust for weather conditions such as temperature, humidity & atmosphere pressure?

theDreamer · 08-22-2009, 09:55 PM

Quote:

Originally Posted by tbss370z

What gear should be used when dyno testing? Is there a formula that you can use to adjusted for weather conditions such as temperature, humidity & atmosphere pressure?

Some allow for things like these, but the best thing to do is either a) do the dyno tests on the same day b) try to recreate the weather conditions as best as possible.

wstar · 08-24-2009, 09:24 AM

Quote:

Originally Posted by tbss370z

What gear should be used when dyno testing?

For your 6MT, do it in 5th, as this is the 1:1 ratio and it's what others have been using. 7AT guys have to do it 4th at the highest, as we hit the stock speed limiter before we hit redline in 5th and higher, even though 5 is also our 1:1 ratio (we have a different rear end ratio, that's what makes the difference).

tbss370z · 08-25-2009, 07:51 PM

I believe I was told the dyno was done on 3rd or 4th gear. How does that affect the results?

m4a1mustang · 08-25-2009, 07:55 PM

Quote:

Originally Posted by tbss370z

I believe I was told the dyno was done on 3rd or 4th gear. How does that affect the results?

If that's the case, the operator probably ran it in 4th, possibly under the assumption that it was a 5 speed. If it was run in 4th, you can probably add 5whp or so.

08-14-2009, 03:10 PM	#31 (permalink)
tooohip A True Z Fanatic Join Date: May 2009 Location: Columbia, MD Posts: 1,626 Drives: 09 370z CY To/Sp Rep Power: 269	I'm going to the dyno that gives my car the most HP! I'll feel better that way! __________________ Lance KW Variant 3 Coilovers \| Stillen Sways \| Stillen Gen III Intake \| AAM HFC \| AAM True Dual CBE \| AAM Comp Oil Cooler \| Hawk HPS Pads \| Volk TE-37 \| Hoser Keg Tap

08-14-2009, 03:12 PM	#32 (permalink)
theDreamer A True Z Fanatic Join Date: Feb 2009 Location: Texas Posts: 30,879 Drives: 370z Rep Power: 4210	Contact some of the board members, they have some great Paint dynos, best numbers yet. __________________ theDreamer's Z // Fast Intentions // Uprev // GTM // HKS // TEIN theDreamer's Silvia // URAS // GREDDY Houston Zs // Facebook // Twitter // Instagram

08-14-2009, 04:02 PM	#33 (permalink)
wstar A True Z Fanatic Join Date: Mar 2009 Location: Houston, TX Posts: 4,024 Drives: too slow Rep Power: 3594	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. __________________ 7AT Track Car! Journal thread / Car setup details

08-14-2009, 05:50 PM	#34 (permalink)
Hi-TecDesigns Base Member Join Date: Jul 2009 Location: Glenelg, MD Posts: 146 Drives: 370 Rdstr AT7 BkChry Rep Power: 15	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. __________________ http://hi-tecdesigns.com/images/pict...on%20Small.gif 2000 S2000 Brickyard Red Metallic w/ Romanesque Crimson Kandy, custom everything else

08-21-2009, 08:02 PM	#37 (permalink)
tbss370z Base Member Join Date: May 2009 Location: King of Prussia, PA Posts: 40 Drives: 09 Nissan GP 370Z M6 Rep Power: 15	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? __________________ 09 Nissan 370Z Base + Sport/Ichiban spacers/Takeda Intake with heat shields/HKS Exhaust/ 88 Porsche 944T, 06 Trailblazer SS/

08-15-2009, 01:27 PM	#36 (permalink)
lando76 Base Member Join Date: Jul 2009 Location: ca Posts: 107 Drives: N/A Rep Power: 15	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.

08-22-2009, 09:54 PM	#41 (permalink)
tbss370z Base Member Join Date: May 2009 Location: King of Prussia, PA Posts: 40 Drives: 09 Nissan GP 370Z M6 Rep Power: 15	What gear should be used when dyno testing? Is there a formula that you can use to adjust for weather conditions such as temperature, humidity & atmosphere pressure? __________________ 09 Nissan 370Z Base + Sport/Ichiban spacers/Takeda Intake with heat shields/HKS Exhaust/ 88 Porsche 944T, 06 Trailblazer SS/ Last edited by tbss370z; 08-22-2009 at 10:08 PM.

08-25-2009, 07:51 PM	#44 (permalink)
tbss370z Base Member Join Date: May 2009 Location: King of Prussia, PA Posts: 40 Drives: 09 Nissan GP 370Z M6 Rep Power: 15	I believe I was told the dyno was done on 3rd or 4th gear. How does that affect the results? __________________ 09 Nissan 370Z Base + Sport/Ichiban spacers/Takeda Intake with heat shields/HKS Exhaust/ 88 Porsche 944T, 06 Trailblazer SS/

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