Anatomy of a 1.271 60 foot

[Alky V6]

Was it the wing that did it?


Sorry I had to...


Great 60'

Come on now.
I put the 91mm on the car and I get grief. I get grief over my torque converter. I get grief over my choice to use nitrous and methanol. Now, I get grief for a wing that I haven't even put on the car yet.

Aren't you even a bit curious as to how a wing might cut down on some of that tire spin on the top end? I sure am.

 

[Alky V6]

Hey, we have been telling you that for a long time
Congrats on the new best

What do you think? Is that big turbo slowing me down?

 

[John Wilde]

Congrats DW, you should try some DRs next.

 

[Otto J]

What do you think? Is that big turbo slowing me down?

I still say yes!!!!
definetly slowing down forward progress

 

[Alky V6]

I still say yes!!!!
definetly slowing down forward progress

Well, I guess I'm still trying to figure out how that's happening, when the darn thing keeps going faster.
Maybe it's the weight of the turbo so far forward that's causing my 13% tire slippage on the top end?

 

[Alky V6]

Bingo! That's why I need the wing! To counter the weight of the turbo in the front!

 

[Alky V6]

I just thought of something. If I'm seeing 13% of tire slippage at the 1/8, I wonder what my true TC slip numbers are?

 

[Alky V6]

I'm a little perplexed here. How does a car perform like this with the datalog showing 13% tire slip on the top end?
If this is true, and I can't see how it isn't with the datalog showing it plain as day, then my TC slip numbers are way off and my BHP numbers are way off. Only 27 psi boost???... only in by the last 2 seconds of the run? Yikes! What a freakin monster.

 

[turbocliff]

Reminds me of when I first broke an axle with a stock rear leaving off the footbrake going 1.52-1.53s... replaced with stock axle and went back to the track and in an effort to not hurt parts decided to lower my launch boost from 14-15psi to 10-12psi and went 1.47s. My theory off the top of my head at the time was that the converter put more power to the ground with the boost "ramping" at launch from 10-15 psi than it did holding the boost to 15psi then launching.

Congrats on the new best. Been 1.27s myself as well and don't know how my 10 bolt is still hanging in there..... lol

 

[Alky V6]

Here is a closer shot of the end of the pass. Some interesting things going on here.
This timeframe (34.22) is the one just before I begin to release the throttle. The cursor is pinpointing this spot on the GPIO7 trace (output speed sensor).
Rpm is 7,294, output speed sensor reading 121.

 

[Alky V6]

The next three timeframes, which encompass .16 second and is where I'm releasing the throttle, show a spike in output speed.
The height of the spike, timeframe 34.38 reads 6023 rpm, 128 output speed (mph). RPM is dropping, but output speed is increasing.

What is this trying to show me?

 

[Alky V6]

The very next timeframe (34.42) after the spike in the output speed reads 5187 rpm, 113 output speed (mph).
The next timeframe (34.48) reads 4846 rpm, 107 mph.
Next timeframe (34.54) reads 4722 rpm, 111 mph.

 

[Alky V6]

I picked 121 and 113 mph as conservative average numbers to use for figuring the mph at the end of WOT and the point where the throttle is fully released.
Using the above numbers calculates to about 7% of tire slippage.

 

[Alky V6]

The next three timeframes, which encompass .16 second and is where I'm releasing the throttle, show a spike in output speed.
The height of the spike, timeframe 34.38 reads 6023 rpm, 128 output speed (mph). RPM is dropping, but output speed is increasing.

What is this trying to show me?

Is this the chassis unloading the rear tires as I'm releasing the throttle?

 

[Alky V6]

Is this the chassis unloading the rear tires as I'm releasing the throttle?

If so, then it appears the chassis is doing some work at trying to keep the tires planted.

 

[Alky V6]

Cal once asked if that was all the parameters I could datalog. I replied that if I viewed all the available parameters at once, the screen would look like a garbled mess. Here's an example.

 

[Alky V6]

Here's the same datalog viewing selected parameters. This run was in February of this year. You can see the same output shaft speed spike at the end of the run. More boost was being used in this pass.

 

[turbocliff]

Are you having a conversation with yourself Don? lol

 

[Alky V6]

Are you having a conversation with yourself Don? lol

Yeah. Nothing new. :tongue:
Actually, I like to document my adventure.

Oh,... let me explain the questions. Often when a question about something pops into my head, I'll go ahead and put it down. I really don't expect someone else to answer it. I know I'll eventually get around to answering it myself anyway.

 

[Alky V6]

She is in dire need of a wing.