hurray for independant cam timing testing!

 

Thanks Andrew...btw, everyone who drives my car is blown away, as well as is everyone who gets left in the dust.

 

How did the -3-3 compare to the -2-2 set up?

 

I didn't run the -2/-2, but it would tend to build torque just a shade earlier and sign off a shade earlier as well.

 

Here is the graph. The red curve is the -3/-3, the blue is the -4/-1.5.

As you can see, the peak power numbers with the latter cam timing are slightly better, however, there is too much lag and torque lost below 4000rpm, which makes it not as quick to respond on the street. At 4000rpm, the -4/-1.5 is down some 40ft/lbs of torque. When it catches up and passes the -3/-3 combo, the difference in both hp and torque hovers only around 5 ft/lbs (and hp).
Essentially what this illustrates is that where changes in cam timing are concerned, you usually give up something to gain something else. As to which is preferrable depends on the intended use of the car. For street applications, I chose to stay with the -3/-3.

 

Hmm.. very interesting.. I like the earlier gains for the -3/-3 Did you find the idle was still degraded with this timing? Since you basically are retaining the same cam overlap..

Too bad you couldn't overlay a baseline (no cams) run on that same graph..

I have to agree, I'd take the gain in torque at lower RPM over the slight loss in upper RPM power..

 

The car has only a slight 'rump' in the idle with the -3/-3.

I couldn't overlay a baseline with no cams because we installed the Vishnu Stg 1+++ setup at once, and therefore we have no means of isolating gains attributable solely to the cams.

 

Interesting results! For 1/4 mile track outings -4 /-1.5 would be better since once your out of 1st you'd be on the powa all the time. I wonder how would that setting would work on a 264/272 setup?...

I tried -3/-1 and it idled like stock and all my vacuum came back. I'm back at -3/-3. Suxors not having a reputable AWD dyno in town.

 

Does anyone have any comments on going 272/264 over 264/264?

Lac

 

Heh. After looking at that graph, I might rethink my stance on this. I like hyperkinetic power delivery. For a racing application, the superiority of the -4/-1 can't be ignored.

 

Rethink is right. Even for racing, torque will get you out of the hole or the corner. The -4/-1 was not best all along. See? Even the dynobutt lies.

 

That might be true for autocross tracks that require more low speed first gear, but in road racing or on the dragstrip, every upshift from ~7200rpm is going to land you in a spot with more power.

 

We could go on and on...I don't have the energy right now. You're right and so the he!! am I.

 

I'm with Noize on this one, I'd take the power over spoolup (plus the smoother idle). However, I seem to spool up just as fast with my 272's at -4/-1 as I did with the stock cams. I don't have a comparison on the same dyno/octane, though

Thanks for posting the charts, TB

l8r)

 

thats a good point......im never under 4000rpm while 1/4 racing..other than my launch ofcourse....so then why would i need the torque at lower rpm points which are never going to be used at the strip except for that first gear.......anyways on the street i usually start from a 4krpm roll in first or second......
so basically that torque wont be used unless your autocrossing or racing from street light to street light.....hmmmmmmm what to do is a good question here...