question for 3barboost

[macster]

quote:Originally posted by 3BarBoost



One other thing for macster. The torque converter isn't locked up at WOT, ever. So the torque multiplication happens a lot of the time when you stand on it. In fact, it is probably biasing your dyno readings (power down and torque up).

I also liked this video http://auto.howstuffworks.com/mpeg/torque.mpg

Okay, dammnit now I gotta say it. What was your take on the dyno info that I posted? I've been waiting for your comments, hell that's why I posted all that #$%^&* it was to get your comments. <---- He busted me out.

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Re: "biasing down" Yeah after that first run, I was suprised how much the puter pulled the torque. (It's almost as if it was an "AI" type of device) Anyway after the first run, my torque values were models of consistency. Unlike my HP readings, which I was able to manipulate. It was also the reason that I kept on with the "the rational" that I was espousing. I seen the damn computer lower the torque 21ftlbs to compensate for an over torque condition. At least that what I assumed it did.

I'm going to do S2 and stop with the engine stuff and just drive the damn thing some. The car runs great, especially with the Brand-X up pipe, I highly recommend it. It will interesting to see if the performance gains will still be there when I dyno it again.

Thanks for the comments.

I will look at the video.

macster

[3BarBoost]

Um, well your dyno results are like the only ones I have seen for an ATX.... Otherwise, looks like normal response. Sorry if I didn't respond, I think I was in a quiet period [B)]

You are clear that I am saying the torque converter as well as the PCM are moving your dyno numbers around? With the mods you have made, crank torque should not be 280 ft-lb. I have probably a bit more top end with my race pipe on - but my car doesn't clear 270 ft-lb on a Dynojet. So the difference is the torque converter multiplication (primarily), because the ATX sucks a bit out of the power stream.

Also, anything after the turbo the PCM doesn't care about, and won't dial boost up or down to compensate - which is why I recommend to everybody and their brother to get a better exhaust.

[macster]

quote:Originally posted by 3BarBoost

Um, well your dyno results are like the only ones I have seen for an ATX.... Otherwise, looks like normal response. Sorry if I didn't respond, I think I was in a quiet period [B)]

Yes I am clear on the fact that the PCM and the torque converter moved the numbers around. But it was interesting that I made that kind of torque by running leaner than normal.

Re:"normal" Thats good, because now I can build a model, and use that data as a reliable baseline for some fine tuning.


done

macster

[hyracer]

Thanks 3BarBoost,

I probably won't go to S3 anytime soon anyway as my GT is my Cruiser and I'm not looking for drivetrain/engine problems when I'm 2,000 miles from home on vacation somewhere. I'm currently redoing my Vette with a larger blower and stroking the block so my drag-strip activities with the GT is just for one or two "fun-weekends" for the year and to give me a baseline on how fast the car actually is.

On the other-hand S1 and hopefully S2 gives me great pleasure on the street or freeway when our "slow" Cruisers blow the doors off most of the other factory cars out there. Even my younger brother, who has no interest in racing or fast cars, called me the other day and was wondering about a PT that had tail-gated him around a freeway on-ramp
(he has a Honda sports car)and then passed him at 80 MPH once he had gotten on the freeway. He now wants a ride in my GT when I come to visit this May. It's this kind of "fun" that guarantees me plunking down my hard-earned dollars for S2!

Deen

[Big Al]

quote:Originally posted by 3BarBoost
...Anything after the turbo the PCM doesn't care about, and won't dial boost up or down to compensate - which is why I recommend to everybody and their brother to get a better exhaust.

The PCM won't care as long as the 2nd O2 sensor suggests the presense of a healthy catylitic converter.

How much can one affect the volumetric efficiency when adjusting the exhaust? I assume it is well within the bounds of adaptive control, but your experience would be enlightening.

What would you recommend for an emissions friendly (pass sniffer test), cost effective exhaust setup for an ideal "stage 1" exhaust system?

[macster]

[quote]quote:Originally posted by Big Al

[i]

What would you recommend for an emissions friendly (pass sniffer test), cost effective exhaust setup for an ideal "stage 1" exhaust system?

Al

I'm not 3Bar, but I live in Southern Cal. I went through the initial smog check with S1 and stock exhaust with no problems. Now I have a 2.5" Cat to muffler exhaust pipe which provides me a better topend.

macster

[3BarBoost]

Volumetric efficiency isn't impacted much by backpressure in four-strokes. That's why you can put a lower restriction exhaust on a modern car and it'll fuel just fine. Same goes for turbos. It is the power-robbing effects of pushing all that pressure out on the exhaust stroke that a better exhaust helps with. Somewhere, I went into this deeper.

Anything with straighter pipes, larger diameter pipes, and generally noisier is better.