[PRAY]

I noticed I gained tq and hp with the stock cam when I advanced it 2* or so and did some other custom cam timing tweeks. With the extra airflow it didn't need to "act" bigger than it was. The problem with just VVT is that the cam specs will always be what they are. You are just adjusting where the cam makes power. Notice also that the stock cam only has a 7* split.

[PRAY]

Originally Posted by DFW1LE

The Hot cam seems to have a very large duration split, low lift, and an overlap that is bordering on being able to pass emissions.
As I understand it, duration, lift and overlap are key factors to determine a cams power making potential, so if you were GM how would you have designed it?

On another point, and I am not speaking specifically about optimizing for best ET, and probably not so simple, but what does everyone think the overlap sweet spot is for achieving a balance of drivability, power, and being able to pass emissions for a street/strip car. I thought it might be about 3-4* of overlap.

Are you referring to a sniff test for emmissions? If so I have no opinion at all. I left a sniff test state 20 years ago. But I think you go to prison for a CAI in that state. You can also do up to a year in jail for miss naming your car a he or she since cars are gender neutral.

I have personally found the overlap sweet spot for engine displacements for power and being daily drivable are dependant on lobe sep as well. LS2 = 9*-11*, LS3 = 12*-15*, 416-427 19*-27*. I have never spec'd a cam with more than 113 lobe sep. EVER.

[DFW1LE]

Originally Posted by PRAY

Are you referring to a sniff test for emmissions? If so I have no opinion at all. I left a sniff test state 20 years ago. But I think you go to prison for a CAI in that state. You can also do up to a year in jail for miss naming your car a he or she since cars are gender neutral.

I have personally found the overlap sweet spot for engine displacements for power and being daily drivable are dependant on lobe sep as well. LS2 = 9*-11*, LS3 = 12*-15*, 416-427 19*-27*. I have never spec'd a cam with more than 113 lobe sep. EVER.

Yes, sniff test. I suspect the overlaps you indicated would not pass the sniff test, although with a catted car, I am not sure.

[PRAY]

Originally Posted by DFW1LE

Yes, sniff test. I suspect the overlaps you indicated would not pass the sniff test, although with a catted car, I am not sure.

I would guess only a couple degrees of overlap would pass. I am assuming you guys don't have visual then? No point in doing the cam if you don't do the intake and exhaust track as well. If you removed that stuff or wnt back to stock intake/exhaust the tune would need to be reworked.

[PRAY]

I am sure there are 10 good shops in DFW that could answer your question if they are dealing with emissions as well.

[DFW1LE]

Originally Posted by PRAY

I would guess only a couple degrees of overlap would pass. I am assuming you guys don't have visual then? No point in doing the cam if you don't do the intake and exhaust track as well. If you removed that stuff or wnt back to stock intake/exhaust the tune would need to be reworked.

No visual, just the sniffer in the exhaust pipe.

[PRAY]

And to your question of the cam determining the power potential of an engine. In a word, no. All a cam does is process air, that's it. There are a ton of other factors that come into play. Airflow in and out and displacement are huge ones. Let's deal with air flow. Volume, velocity, swirl, tumble are a few things to consider. Valve size and C/D are another. C/D being the determine of efficiency most of the time. Basically a head with the smallest runner for the displacement with the most flow wins. The more efficient the heads the less duration you need to make the same power. But flow efficiency goes from air filter to muffler. There is also the factor of the entire lift curves airflow number. That means all the way up and down the lift curve for the intake and exhaust runners. Those also need to be flowed with your IM/TB and a chunk of your exhaust pipe to get accurate numbers. Once I have all of those numbers along with all the specs on the total car and it's intended purposes, then I design the cam.

[PRAY]

Originally Posted by DFW1LE

No visual, just the sniffer in the exhaust pipe.

Hmm, that would be an interesting challenge. Kind of a cool way to do it. I would go heads, tiny blower cam and a F1.

[BlackbeastSS2]

Originally Posted by PRAY

And to your question of the cam determining the power potential of an engine. In a word, no. All a cam does is process air, that's it. There are a ton of other factors that come into play. Airflow in and out and displacement are huge ones. Let's deal with air flow. Volume, velocity, swirl, tumble are a few things to consider. Valve size and C/D are another. C/D being the determine of efficiency most of the time. Basically a head with the smallest runner for the displacement with the most flow wins. The more efficient the heads the less duration you need to make the same power. But flow efficiency goes from air filter to muffler. There is also the factor of the entire lift curves airflow number. That means all the way up and down the lift curve for the intake and exhaust runners. Those also need to be flowed with your IM/TB and a chunk of your exhaust pipe to get accurate numbers. Once I have all of those numbers along with all the specs on the total car and it's intended purposes, then I design the cam.

Yup, on the above comments. Air flow is what I want more of, next project to tweak my motor is larger TB. I made the mistake of ordering a 92 mm top on my tunnel ram. Ordering the 105 mm top with a 105mm Holley TB with mechanical attachment and will at some point change to cable throttle because I do not like the Camaro lag off the line even with a tune.

After I get TB worked out with tune and is running right it wil be time to test out a NOS bracket in the tunnel ram for a max 150 shot. Looking to start that project late September. Then a meth/water injection and I think that pretty much completes my build.

[PRAY]

Originally Posted by BlackbeastSS2

Yup, on the above comments. Air flow is what I want more of, next project to tweak my motor is larger TB. I made the mistake of ordering a 92 mm top on my tunnel ram. Ordering the 105 mm top with a 105mm Holley TB with mechanical attachment and will at some point change to cable throttle because I do not like the Camaro lag off the line even with a tune.

After I get TB worked out with tune and is running right it wil be time to test out a NOS bracket in the tunnel ram for a max 150 shot. Looking to start that project late September. Then a meth/water injection and I think that pretty much completes my build.

That cam and exhaust port will roll on the bottle. I am sure you are limiting the shot due to the stock pistons but you could get away with a lot more than a 150 shot with your combo.

If you tweak your driver demand and torque coefficient tables and your TB is ported correctly there shouldn't be any real noticeable lag. My honest opinion is that this combo is just going to be soft on the bottom no matter what you do. It should scream up top though. Launching from a roll at 5K should be a blast in 2nd and 3rd.

When you switch to cable driven you are going to have to do a write up on everything that was needed. I am sure there are a lot of people that want to ditch the DBW.

[drivingagain]

I wonder if this every got to a dyno? Really would like to see if the cnc heads and cams are worth the change?

[BlackbeastSS2]

Originally Posted by drivingagain

I wonder if this every got to a dyno? Really would like to see if the cnc heads and cams are worth the change?

In my case it's all about the build. I don't want a slap on supercharger and then that's it, done with build. So far I love it, cruising listening to my engine fully natural aspirated. with the tunnel Ram on in my opinion it gives a better sound then the 2015 Z28 which I could listen all day to.

It's not all about numbers, it's the complete package. I will base my build on final track numbers on the line, not a dyno .

[PRAY]

Originally Posted by BlackbeastSS2

It's not all about numbers, it's the complete package. I will base my build on final track numbers on the line, not a dyno .

With that in mind, will you be doing a converter and drag pack?

[PRAY]

Here is what they flowed on my bench. The intake port flowed identical to stock. It must need more velocity to show out. Hopefully at 28" of depression they do a bit better. The exhaust port did pretty well at .4-.6.

http://www.camaro6.com/forums/showthread.php?t=503689

Here is the stock head vs. my head on my bench.

http://www.camaro6.com/forums/showthread.php?t=483048

And my head vs. stock at 28".

http://www.camaro6.com/forums/showthread.php?t=492595

As you can see there is a large jump from my bench to a 28" bench. So the GM head should do a bit better at 28". I just didn't have time to test it at that depression.