Serious Dyno Pull Question !! Read !!

[siman]

Hey guys,

This is a question from ME and MY benefit ( my supra) as well...I am dyno'ing my car this weekend!!!

My father took his 350Z roadster ( auto/manual) in for the dyno this morning....we were figuring about 270ish whp because of the auto/manual tranny....20% drivetrain loss....that makes the motor roughly 315-320 at the motor off my head....

well, he is on his way home right now but he dropped off the video camera and told me to watch all 6 of his runs. ( note that the 350 auto's are 5speed, not 6 speed like the manuals)....they were ALL in 5th gear...and ALL of them were pulls to TOP END ( 167mph @ 7000rpm, he really cuts of at 7600..??).

He only pulled 254whp and 266lbs/tq....weird.....very weird. The first thing I saw on the video was camaro's and corvettes...and the import biased thoughts begin to play in my mind.

This was my fathers FIRST ever dyno pull and he did what the guys told him to do...I think they ran him out the door and took his $100...ugh.

I was reading MULTIPLE web page documentary's about dyno pull tech ( like 4 of them, I forwarded them to my father to prove my theory and point that they dyno'd him wrong). All of them noted ( as I have been tought all my car life) to pull in 2nd or 3rd gear....being 3rd is on the 1:1 ratio, my father did not know this. I was not able to be present at the dyno this morning because of my work schedule.

He is wanting to get ACCURATE numbers for a Z car show this saturday!

What do you guys think about hp difference in 5th gear top end pulls? Much less on an automatic....5th gear internal rotational masses are far more than that of 3rd gear ( 1:1)....I think he may of lost 10whp because of this!!!!


what are you guy's thoughts?

reguards,

Jonathan Mann

PS: this was on a brand new Dyno Jet chassis dyno model #224X
http://www.dynojet.com/automotive_dyno/224x_dyno/index.php

 

[glntom]

I thought 4th was 1:1 in the 350Z auto tranny......but your are right, pulls in overdrive will show lower hp&torque unless I am badly mistaken.

 

[kwnate]

350z comes with 270 or 280hp doesnt it??? If so with an auto tranny that would be some good numbers I would think... Experts chime in anytime :icon_bigg

 

[siman]

3rd gear in every car ever made is 1:1 ( well I cant say EVERY...but you get the jist'). On every run they put him in 5th.....and on the dyno chart, you could planely see that the cams ( JWT stage 3) still were pulling past 7K rpm.....when they cut him off...his ECU ( technosquare) puts the rev limit at 7600!!!)....I have a STRONG feeling those guys running the dyno had not a clue what they heck they were doing.

Second, I know something is wrong when a 3.5ltr V6 makes more hp than tq....( 254whp/ 266tq)....that just does not supposed to happen on N/A cars....that was another red light to think something was a-miss.

Stuff like this just makes me so angry. :nono:

-Jonathan

 

[kwnate]

4th gear in your supra is 1:1... But anyway can you post the dyno sheet?

This shows a dyno from a stock 350z 229rwhp so he did gain...
http://dynoperformance.com/search_details.php?ID=408&safeid=408

 

[glntom]

just checked Nissan site, 4th in auto is 1:1, only 5th is overdriven(just as in supra 5spd manual) They did shortchange him pulling in 5th, and they should be/are well aware of it I am sure

 

[siman]

4th gear in your supra is 1:1

Last time I looked ( long time ago..memory may be off) at the speedo accelerating in 3rd, the rpm and speedo gauge rose together, signifying a 1:1 ratio in 3rd.....where did you find that info from?

But thats besides the fact anyways...they dyno'd him in TOP gear...WTF! :icon_surp


-Jonathan

 

[kwnate]

Is your supra an auto? cuz 3rd in an auto is 1:1, but who the hell wants an auto anyway...

http://www.geocities.com/ma71supraturbo/
click the mk3 tech link

 

[siman]

The 6spd manual:

Transmission

Gear Type 6 Speed Manual
Final Drive 3.54:1
1st Gear Ratio 3.79:1
2nd Gear Ratio 2.32:1
3rd Gear Ratio 1.62:1
4th Gear Ratio 1.27:1
5th Gear Ratio 1.00:1
6th Gear Ratio 0.79:1

Now the auto from what you say is 4th that is 1:1. ( father just checked in owners manual as well).

-Jonathan

PS: I am a R154 5 speed ( turbo )

 

[siman]

Is your supra an auto? cuz 3rd in an auto is 1:1, but who the hell wants an auto anyway...

http://www.geocities.com/ma71supraturbo/
click the mk3 tech link

Holy shizz! My car is on that website! Hahahha

LOL.....that made my day!

-Jonathan

 

[IJ.]

99.9% of 5 speeds 4th is 1:1

Only exception I can think of off the top of my head were early 180B SSS they had a 1:1 5th gear.
(and I was taught dyno pulls were done in the 1:1 gear to cancel out any torque multiplication/division from the trans)

 

[siman]

99.9% of 5 speeds 4th is 1:1

Only exception I can think of off the top of my head were early 180B SSS they had a 1:1 5th gear.
(and I was taught dyno pulls were done in the 1:1 gear to cancel out any torque multiplication/division from the trans)

I was waiting for your input!!! LOL...

Thats what I was tought....and it was my misunderstanding that all 5speeds usually had 1:1 ratio in 3rd! Tells me not everything is set in stone!

But still. They did the dyno pull wrong.....LOL

-Jonathan

 

[IJ.]

LOL just stopped for lunch !

Anything other than 1:1 will give a different reading that you need to factor in.

 

[kwnate]

LOL just stopped for lunch !

Anything other than 1:1 will give a different reading that you need to factor in.

Just finished dinner myself :naughty: Take the car back and havem dyno it in 4th gear, ask them y they did that and get it dynoed for free, unless for some unknown reason the did it on purpose??

 

[IJ.]

Another horrible thing I've seen some Dyno operators do is do a pull then shut the motor off right away.......

 

[siman]

Well after reviewing the video it is infact that most of the dyno pulls were in 4th....with my FATHER at the wheel.

Now the dyno operator did the last 2 ( and the highest HP/Tq numbers out of the 7 pulls they did) pulls in an UNKNOWN gear.....but by the dyno litteral sounds...he was in 5th pulling to TOP END. :nono:

I can boot up the dyno graph tonight somehow of all the pulls....

And after reviewing the 350z car sites out there, it seems he is right on the money with his dyno chart.
Though 37% humidity and 85 degrees in the building does not do much for the car! YIKES!!!!

and I was reviewing the A/F ratios through the Rpm that the dynographer jotted down...

2000 rpm = 14.4
4000 rpm = 13.0
5500 rpm = 12.2
6000 rpm = 11.7
7000 rpm = 11.4 ( IS THIS NOT RICH???!!!??? ) < someone explain this reading!!!

But I do believe the difference in his car vs. other Z cars is that his cams are really good on low end torque..being that the car idles like a BEAST and he had MORE tq than hp???

someone tell me what you make of those readings as well!

-Jonathan

 

[siman]

http://autospeed.drive.com.au/cms/article.html?&A=1595

I was just reading this....between 4500rpm and 7000rpm the ratio varies from 12.8 ( I guess thats a pretty good a/f ratio given the above documentary) and then richens to 11.4 at 7000rpm.

Now I am guessing if he leaned the curve of a/f out right at 6500rpm up to 12.5 maybe even 13 ( experimenting) he should see a steady plateu or just climb on the curve!

EDIT: I cannot at this moment display the dynograph....LOL

-Jonathan

 

[Blue87T(Dan)]

Sounds like a slow 30K+ car.

He should have gotten a Supra or at least a G35 since those look much nicer than the Nissan.

Why didn't he know what gear he should be in to dyno?

Was he listening to you?