Initial thoughts on Pete's Intake/Exhaust cam combo

[Paul Workman]

453sh at the wheels @6868 rpm...Extreamely NICE! There is tons of "meat" under that torque curve, to be sure. Congratz! Looking forward to how it runs at Monee next weekend!!

P.

[Karl]

Originally Posted by XfireZ51

Here's the compare between Intake/Exhaust cam combination vs. Intake only cams. Each has ported top end and heads.
Top line is current config but prior to tuning.





Here's where I started and ended the tuning session. This was all fuel. Timing really made little to no difference from previous.

How is the idle with the cams? Does it idle like stock, nice n smooth, or is it choppy, like a big cam race car?

Nice numbers too!

[XfireZ51]

Originally Posted by Paul Workman

453sh at the wheels @6868 rpm...Extreamely NICE! There is tons of "meat" under that torque curve, to be sure. Congratz! Looking forward to how it runs at Monee next weekend!!

P.

Yeah Paul. No less than 350rwtq from 3700 to 6700 rpm. Rather broad torque curve.

[XfireZ51]

Originally Posted by pushrod-v8

How is the idle with the cams? Does it idle like stock, nice n smooth, or is it choppy, like a big cam race car?

Nice numbers too!

No it doesn't idle quite like stock. Idle is somewhere around 875-925 at 52-54kPa or about 15"Hg. It has a deep bass note to it but the Z06 exhaust valves do a nice job. However, the car idles MUCH better than an OHV 5.7L would that puts out >530hp. Just think of the bumpstick you'd be using in order to reach a HP peak of 6800rpm!
More valves are better than 1.

[XfireZ51]

Once I got the vacuum leak issue resolved (loose fuel rails), I started datalogging again to refine the part throttle tune. I don't think the vacuum leak would affect WOT much due to equal pressure inside and outside the intake tract. Pretty much have it dialed in now ( famous last words, right Todd ,
with idle in the 875-925 range, and IACs at ~20. Had an opportunity to take a long drive w it and recorded 23mpg @ 75-80mph. After about 600miles, the tailpipes are not sooty but more of a golden color w the chrome visible under the slight film. WB registering 14.5-14.9, and BLMs ( running and idling in Closed Loop) avg. 127. Ran like a champ and blew off a few pretenders along the way at part throttle. So overall, the motor drives and runs well, idles and doesn't stall.

[ALZR1]

Originally Posted by XfireZ51

Once I got the vacuum leak issue resolved (loose fuel rails), I started datalogging again to refine the part throttle tune. I don't think the vacuum leak would affect WOT much due to equal pressure inside and outside the intake tract. Pretty much have it dialed in now ( famous last words, right Todd ,
with idle in the 875-925 range, and IACs at ~20. Had an opportunity to take a long drive w it and recorded 23mpg @ 75-80mph. After about 600miles, the tailpipes are not sooty but more of a golden color w the chrome visible under the slight film. WB registering 14.5-14.9, and BLMs ( running and idling in Closed Loop) avg. 127. Ran like a champ and blew off a few pretenders along the way at part throttle. So overall, the motor drives and runs well, idles and doesn't stall.

Good Job Dom.

AL.

[XfireZ51]

Al,

As usual, just one more tiny, little, itsy bitsy small tweak. Trying to see if I can get it to idle at 850 w IAC counts. Might try to do some "smoothing" next. Maybe. Or maybe I'll leave it alone and just drive it without a laptop on the passenger seat.

[XfireZ51]

After addressing the loose fuel rails and reading a bit more on the 3rd Gen forum, I started playing with timing at idle. Also continued to lower the IAC counts in the MAT table. Taking the car out for a drive in the lovely Chicago weather we are having my idle IAC counts were at 15. What's really nice is that the motor idles more smoothly and at ~ 850. I initially had idle timing set at 21d, now it's at 17.
So I am thinking that my IAC counts were disappearing because the timing was keeping the motor from idling down any further and as motor got hotter it was more difficult to bring down the idle. Another lesson learned. Thanks again RBob.

[cvette98pacecar]

Originally Posted by Pete

Hi Dom

I hear you need to give the car a push start from stop lights.

Pete

Pete, That is because he is trying to increase fuel economy by using nothing but 6th gear.