Tell me about it...we passed out lots of 215-220whp'ish dyno charts to stock 350Z's, and G's. But most people in the know, understand that the DD reads lower. The weird thing is, when we did our same day independent tests at the local dynojet, the numbers were somewhere between 7% higher, and 14% higher. So far, we have taken Alberto's and BamBam's car over there...and one other customer that I cannot remember. All I know, is that they are higher on the DJ, but its just too difficult to narrow it down to a correction number.

 

the thing about any sort of correction (like adding 13%) is misleading in how to factor that in. What you need to do is add correction to the tq curve, then recalculate hp with the hp formula by hand

If you take a graph, you can't just go and add 13% to both the torque and hp graph because the numbers won't work themselves out for the hp=(tq x rpm)/5252

so if you make 240whp on a DD, and you're told to add 13% (which I think is actually closer to 6% IMO), you can't take 240 x 1.13 and think you get 271whp

240whp at 6600 rpms = 190 tq at 6600 rpms

so you take 190 x 1.13 = 214
214whp x 6600rpm/5252 = 268whp, not 271

I really don't believe in the 13% figure, but just using it for this example



the reason this is so important to just look at tq and not hp is because of how hp tilts around 5252 rpms. So you can't just add a correction % across the board for hp. But you can for torque and then recalculate hp with the hp forumula

for example:
At 2000 rpms, you might make 60whp and 157tq. Adding 13% to that would make it 76whp and 177tq which are incompatible

177tq @2000 rpms DOES NOT = 76whp @2000 rpms (177tq x 2000rpms/5252)
it equals 67whp
which in the end is about 11.5% difference, not 13%

 

IMHO I think that some people are just a little scared of Functioned Tuned and the information that Dave seems to have. Both Sharif and Dave are always messing around with the VQ and the Z platform, breaking down motors, pushing the limits of the stock block, and making an AWD Z to name a few of their most recent adventures into our cars. This is why, when my Vortech goes on, my car will very likely be in the hands of Dave or Sharif.
Audible, I understand that you want the car to go ***** out at WOT down the 1/4, but you also have to realize that not everyone lives for the 1/4 and even those who do, want a car that can haul *ss on the street/corners. Not trying to start sh*t just giving you my opinion/insight into what potential customers such as myself look for.

 

as i have said before, you dont race at 50% throttle ever. all my cars run just fine at any throttle position, thats not even the issue. BUT all my customers would like to have ALL that they can safely get out of what they bring me. i just know that trap speeds dont lie and there are NO corrections you can do to them so it is the only real proof of how fast your car is that is not debatable...

 

i think you're missing the point... not everyone builds their cars to "race"... keeping a smooth idle, smooth powerband and having it feel as close to stock as possible when not at WOT is what he's speaking about... i think dave was trying to express that DD's are better tools for tuning a car this way than the DJ... i'm sure your cars are wonderful...i don't think anyone is calling out your tuning prowess... but, most guys here who have gone FI or are considering FI are not in it for trackability, but quite the opposite...streetability...

 

I think what Jeremy is trying to say is all this Hp talk is just BS, and just going down the strip if your a drag racer or not will help you understand how fast your car really is with you driving it. I have ran the Greddy EU, Utec, and now have a Fcon, and I never had a problem with tuning at part throttle, but I have had small easily fixed issues at full throttle. I am now going on trap speed instead of HP becuase this Hp thing had me chasing my own tail. I have dyno everywhere from 410 to 470 on diffrent dynoes with my current set up, but trap 116.7 to 119 on cold days. Bottom line traps dont lie, all you guys with 500+ Hp traping under 120... Well geuss what!! You dont have a 500hp car.

 

i understand the point, i am just saying, we all want our cars driveable and streetable, all my cars run very very smooth with no issues, i wont let them leave my shop with issues. this all can be done on a dynojet and this is what started the arguement. if you would like tons of examples, come down to florida tomorrow and drive around in ALL my cars, you wont be disappointed they all are smooth idling, smooth powerband and track proven!! if you want your car setup not to go fast, thats even easier to do...

 

i think this whole thread has become the flogging of a dead horse... in my opinion, it all boils down to this: you can remove a phillips head screw with a flat head screwdriver...but, it's not the best tool to do it with...

again, i'm sure your cars are superb... i've never heard of a single complaint stemming from your work... so, i don't need to come to florida for examples... though, i do appreciate the offer...

and if i do ever find myself in need of setting my car up to go slower, i'll be sure to drop it off at your shop... *haha* j/k...couldn't resist, bro...

 

Just a few corrections to the first post:

1) Horsepower is not an "averaging number". It is an instantaneous value at a specific RPM just like torque. Quoting horsepower is useful because increased horsepower is an indicator of increased high rpm torque, which pushes your shift points higher in the RPM range and let's you take advantage of gearing to increase the force to the ground that is accelerating the vehicle.

2) An inertial roller is a very good simulator of a particular vehicle mass accelerating. What it does not take in to account however is drag force and variances in vehicle mass from vehicle to vehicle (while a load-generating dyno can). Much like a real car, it does not get easier to accelerate the rollers once they are moving (neglecting rolling resistances).

3) Tuning a motor at constant speed is clearly not representative of the load in the real world. For one, you eliminate all inertial losses from angular accelerating components (wheels, driveshafts, flywheels, etc). Clearly there are dynamic aspects to the tune that need to be verified separately from a constant speed environment.

 

HAHA, when will the name calling start? I think this is a very informative thread and thanks to all involved for there info... BOTTEM line...i know the shops around me that i can and cant take my car to Dyno on from other customers who have had there cars totally ****ed up from a bad TUNER... so lets all just agree that all those bastards should burn in hell who don't know what they are doing and take your money all the same... right? good we all agree on something... and we all hate Carrot Top too

 

is this bump old threads week??

 

Opposed to the never ending thread bump week? Yes it is.

 

haha..you guys are both hilarious!

 

ooooooooo, sick burn!!

 

See, you just bumped it again!!

 

then again... carrot cake is delicious... so maybe we just dont like carrot top by association...?

 

 

Wouldnt putting in higher or lower temp and humidity numbers in alter the numbers ????????

 

You just made me go thru part of this thread again you nooooooooob ***.

 

Wow! thanks! Not only do I understand it a bit better now (I will need to read it at least 3 times!) but not my I.Q. has shot up at least 12 points!!!!
Nice write up!