DataLog Quiz *** Low or High Gear

final5-0 · Nov 9, 2006

This stuff came from a thought I had over in the tech section where we were talking about how things work such as the load on the fuel pump in a low or high gear.

This be it if you wanna see it

http://forums.stangnet.com/showthread.php?t=670432

anyway ..............

A little bit different topic to make you think a bit
but
The low/high gear thing comes into play here as well

Say you wanna use your Tweecer & wide band, and your intent is to tweec the upper end of the maf curve to dial in your final wot af ratio.

Do you wanna use 1st, 2nd, 3rd, or 4th gear to make your test & tune runs

btw ... traction will NOT be an issue in this little discussion

Nobody has a reason to feel like they can't get involved
even
if they don't know the answer
heck
You don't have to know anything about tuning either

I just thought it might be fun
to
kick around something ....... a bit different

Lets hear it my SN Friends

What are your thoughts

Grady

Guero · Nov 9, 2006

Would 1st and 2nd happen to quick to make any good adjustments??? When i took my car to get dynoed a while back. I asked him what for, and he said it gave more accurate results

final5-0 · Nov 9, 2006

Guero said:
Would 1st and 2nd happen to quick to make any good adjustments??? When i took my car to get dynoed a while back. I asked him what for, and he said it gave more accurate results

For a while in this discussion .......

I'm not gonna offer any of my thoughts

however

Would you care to expound on those .................

"More Accurate Results"

Grady

WhiteDevil · Nov 9, 2006

I usually use 3rd for MPH reasons but if i had it my way i would use 4th. The RPMs rise slower and you can get more information in your datalog if you were able to use a fourth pull. For my 4th goes like 125mph which im not really comfortable hitting on San Diegos traffic freeways.

69clark · Nov 9, 2006

Just a guess- I would say that in order to be accurate you would want to test in each gear being the load at a give rpm is different in each gear.

69clark · Nov 9, 2006

WhiteDevil- That is exactly what I have alway done when gathering datalogs and for the same reason.

blksn955.o · Nov 9, 2006

I have always thought the highest gear or gears (remember the log will catch the WOT if you hit it in a couple diff. gears).

I would also like to log at least one higher gear that would keep me WOT for the longest amount of RPM range...like say 3rd or 4th. That way you have more data points in the log.

In the end I would say the highest gear you can saftly drive the car while at WOT. I like my loop its a good bit of stop and go lights and then a 4lane hwy with long exit/merge lanes that is close to another 4lane hwy that meets up with a "back way" home that has stops on hills and a good bit of 35-45mph driving takes 20min. to do with 3 places to "get on it" and I can even quickly pull a Uturn after getting on the 2nd hwy and make the reverse trip and that Utrun is at the exact 1/2 point.

In the end more is better.

final5-0 · Nov 9, 2006

Well Guys

Thats kinda how I see it

You can only get in so many data samples in a second

Soooooooo

The higher gear gives you more data which is always good
but
The speed can get outta hand in a hurry which is bad

also

In this case ... you have put yourself in a max load condition so that is gonna work the entire fuel system to its maximum. If something is gonna be weak here, this gives it the best chance to make itself known to you.

Grady

cbarr300 · Nov 9, 2006

I use third going onto the highway to get my wot points. Fourth is just a tad bit faster than I care to go.

I got the points......now I just need to fully learn how to use them lol.

Killercanary · Nov 10, 2006

I'd use 4th if I were able to datalog in my car. It would offer the greatest load and time for datalogging as you all said.

You have my mind going Grady thinking about even more than was mentioned here already, such as how much does air resistance effect load (going further, should this test be done at certain MPH or a certain gear; those with stock gears can go nearly as fast in 3rd as I top out in 4th with my 4.10's so is the MPH versus air resistance something that should be concidered here as well versus just picking 3rd or 4th gear), does air resistance lead to a slightly leaner condition on the street/track than it did on a dyno due to air resistance creating more of a load on the car during acceleration, how does heat soak/increased heat due to a longer WOT period of a higher gear effect the load and therefore fuel and timing tables?

I'll be thinking about this all day now as I drive around for work. Thanks!

69clark · Nov 10, 2006

Good thinking Paul! Now I will be thinking at work about this! I know air resistance applies to those handhelp performance meters as compared to dyno when measuring HP and torque, why wouldn't it affect the load. Good thought!

final5-0 · Nov 10, 2006

Here is something to think about based upon my observations.

When me and all my gearhead buds were just starting to be exposed to all this hot rod stuff ......................

We spent many, many hours at our local 1320 strip.

For a good while back then .......................

It was a mystery to us why a lot of those really fast cars would break on the big end in 4th gear.

Hummmmmmmm

Grady

DataLog Quiz *** Low or High Gear

final5-0

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Guero

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final5-0

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WhiteDevil

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69clark

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blksn955.o

final5-0

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cbarr300

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Killercanary

The car that set the bar.

69clark

final5-0

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DataLog Quiz *** Low or High Gear

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