Stingy74

Edited for multiple spelling misatkes. Bet I still missed some.





[Modified by Stingy74, 7:26 PM 6/20/2004]

Sandra Bigwoode

[b]did you know that the throttle is controlled-by-WIRE-from-the-pcm and you can floor the gas pedal all you want but the pcm will not command the throttle butter-fly fully open until all other conditons are met for WOT?

did you really think that doing a cam change with stock heads was really going to make a big difference? what's the point of ripping out the cats and keeping the stock cat backs?

have you considered posting a before and after dyno run to show us all this new 'power' you have uncovered?

427CPE

stock cat backs are fine and removal only creates a loud obnoxious sound gaining very little if any power.

Stingy74

Of course. Those conditions are being met alot faster now.

It really did make a difference. What was greater than the power gains was the complete drivability of the car. A cam that size in my 74 small bloclk with a carburetor isn't going to come close to acting as well. The main cats were determined to be a restriction as was the throttle body. Just look at your manifold vacuum as you change these parts. The stock cat back will stay in place because it's light and quiet, and the gains from going to something loud and obnoxious from any of the good suppliers isn't what the owner wants. It's a compromise.
We don't have a dyno close by. Nearest is 6.5 hours west in another province. The car isn't some fire breathing monster with all this "new power" as you say. It runs and drives great and was relatively easy for the owner to tune. That's all I was trying to get by.


[Modified by Stingy74, 10:22 AM 6/9/2004]

itsonlyairandfuel

Interesting post. Someone else posted about a company takinge off the MAF and going speed density. I believe they were in Australia. And they were having great success with some very radical cams. I didn't know about the default mode to speed density. Is tuning done with the same tables, with the two different systems? Speed density worked great on my 91 corvette. My bet they switched to a maf system for emissions. Thanks for the info. Ron B.

Stingy74

Anyone have a copy of what I had posted here? I lost it a few weeks ago when fixing spelling mistakes. The car did make it to a dyno. Made 404rwhp with mild cam, no cats, 1 3/4 tpis headers and bigger throttle body. Still more power to be made as there's still 3 percent positive fuel trim to correct. Going by the usual 16-17 percent drivetrain loss this makes 470 flywheel hp. Just a little more tuning and 500 will be real close. I still can't get over how mild it is at idle. Most wouldn't know it has a larger than stock cam in it. Dyno sheet available if you want...just have to get the owner to scan it in.

nuke61

Going to Speed Density was done long ago by the LT1 crowd. All accounts said it worked great after tuning.

Got uid0

[Modified by knowledgefreak, 4:57 AM 7/8/2004]

nuke61

It's been this way since 1997 when the LS1 was put into the Corvette. "By wire" commonly means that its controlled electically. For instance, the F16 was often described as a "fly by wire" jet. It is highly unbalanced and I read articles that said if not controlled by a computer, a pilot would quickly lose control of the jet. It's instability also makes it highly maneuverable. So "by wire" has come to mean that there's no direct mechanical control.

Got uid0

i know it is electrical wire and not physical cable that was my point

maybe i misunderstood

chuckster

No worries... Drive "BY WIRE" is the terminology for electronic.. A throwback from the jet fighter world where they have "Fly-By-Wire"