bowtieman81

iTrader: (35)

So if I am understanding things correctly, if you have a wideband O2 and the ability to log data you can tune your car without ever using a dyno. Is this correct? Would there be any advantages to using a dyno? Seems to me that the new LC-1 at $199 is a heck of a deal if you don't need a dyno, since most dynos rent for $75-$100/hour. Thanks.

slow

iTrader: (7)

You don't "need" a dyno, but given the crappy sample rate for GM scanners, you really can't get the data needed for tuning using a 1, or 2nd gear pull. 3rd and 4th gear pulls are not safe on a public highway, (however, that does not stop people from doing it)

Granted my opinions are a little biased, as i have access to a mustang dyno in the next room.

Ryan

pknowles

iTrader: (1)

Now that I've started nailing down my timing, I'm going to do 2nd gear pulls and look at the time it takes to go from a certain rpm to another rpm. The shorter the time, the more power I'm producing assuming the same conditions on the same road. If you don't log a lot of parameters (under 6 bytes) I can get data rates as high as 40 frames per second; that's high enough. So, I would log rpm, TPS, timing, mass airflow, and AFR on my wideband. I havn't tried it yet, but once I get rid of all of my knock then I will.

foff667

iTrader: (2)

I prefer not tuning on a dyno...in my case my origonal tune was less then desireable and so started tuning myself...also the last time i hit the dyno with my 00 gtp i was seeing a ton of KR at wot whereas on the street with the same tune i got 0-1* personally my feeling is like your on the street or at the track when you really get to use that tuning so why not do it there...99 % of tuning isnt about wot anywayz...shift points and idle are the first things to do which can be done on the street...wot shift points/fueling/timing should be done at the track imo. My tuner never took my car on the street at all to make sure part throttle, TC lockup, shift points were all kosher and trips 1/2 way across the state for the proper adjustments was getting old and in the end they couldnt fix the part throttle issues I was having nor the TC lockup points yet in 30 mins of tuning on the street i had both of those issues fixed :shrug:

bowtieman81

iTrader: (35)

slow, I am confused. How is sampling rate on a dyno different than sampling rate without? Is'nt the sampline rate based on the wideband used and the tuning program?

foff667

iTrader: (2)

with 3.42 gears you'll probably be in 3rd gear longer in the 1/4 mile then you would in 2nd....so you'll get alot more info frame by frame in 3rd yet third might run you to 100mph on the highway which obviously isnt legal. Basically if you do a first gear run you'll be in first for about 1.5 seconds lets say so you might get 15 frames of info total...2nd for lets say 3 seconds so you'd get about 30 frames...and 3rd for say 7 seconds so 70 frames...obviously the more frames the more accuratly you can tune at a specific rpm for a/f or what you want to tune at that point.

lata
Bill

Black02SS

iTrader: (36)

If you use a stand alone dataloging program that doesn't go through the PCM, the sampling rate will be faster as the PCM has a limit of how fast it transfers data.

slow

iTrader: (7)

a 4th gear pull on a loaded dyno will take a lot longer than a 2nd gear pull on the street. If your doing a 4th gear pull on the dyno it is similar to the street, but hitting 6,000 rpm's on a public highway isn't reccomended on a stock geared f-car

with my hp tuners on the street, I have maybe 10-20 frames to view for data on a 1 or 2 gear pull.

When I dyno other brand vehicles, I typically have 300-5000 frames of data to deal with.

Ryan

bowtieman81

iTrader: (35)

Understand now, thanks guys. It sounds like a dyno is convenient and the best way for tuning WOT, but for part throttle a dyno is not best nor most economical.

foff667

iTrader: (2)

i usually bring the car to the track and do a nice 3rd gear pull with minimal parameters <11 and use the internal timing system in hptuners to figure out what timing is best, never had a problem

slow

iTrader: (7)

track and 3rd gear pulls work great, when you can get some decent runs in.

locally, 2 runs is a good night at the ice rink, (orlando speedworld)

Ryan

Redline-Motorsports

iTrader: (3)

I agree if you are using a Dyno Jet 248! If you have access to a "steady state" dyno like a Dyno Dynamics or Dyna Pak you can tune a car in half the time with WAY more accuracy then on the street. Of course it may require so fine tuning for track conditions but you won't waste time and kill the motor.

seadoo

how do you use the HPTuners internal timing?? what does it actually do?
thanks, Im VERY new to tuning

thanks,
Jason

foff667

iTrader: (2)

hptuners has a timestamp...sorry wrong terminology.