Dynamometer Results & Comparisons - Very interesting Cam Degree dyno results

I'll try to keep this as short as possible.

This is a 346cid TFS CNC headed Z06 with a low-mid 230's duration cam with a 112 LSA. When degreeing the cam we found that it was 3 degrees more advanced than we ordered it as. So we used a Hex adjust timing set from Comp Cams and rolled it back -3 degrees.

The car made good power and flat torque however I felt like it was missing a little down low. I didn't go up much at all in cam size but the car felt less torquey and snappy than with the cam only/stock head setup it had before. I wrote off the sloppy feeling to maybe the heads just being a little lazy on the street.

Since that time I began to think about how we degreed the cam in. We used the traditional .050+ and .050- within max valve lift to find the lobe center but this leads to some questions. Does max valve lift really constitute the lobe center? Well, I'm beginning to think with the modern high lift lobe cam lobe designers are having to push the lobe to a more asymmetrical design to keep the valve train alive. This cam uses LSK lobes which if that theory is true it would be true with these lobes and this cam. If I had it over again I would have checked it at .050, .100, .300, etc just to see if I was coming up with the same number. BTW. We did reverify cam timing after setting the hex adjust timing set and it was coming right on the money.


4.20.2008

Ran the car a couple of times to work out some bugs and collect data in anticipation of this experiment.

6.3.2008

Installed the cam straight up and dynoed the car again. The car has been driven less than 10 miles since dyno runs on 4.20.2008


For the data I used the average of 4 best runs from 4.20.2008 in RPM iterations of 50 RPM and likewise for the 4 best runs from 6.3.2008. So what your seeing is not one run compared against another but 4 with the average power in 4 runs at 2700, 2750, ect. Correction method was SAE. Dyno used was a DJ 224xLC. No other changes than camshaft timing. AFR was reverified and it was exactly where I left it.


I'm honestly surprised that horsepower/torque peaks didn't change and also there was not much change in power and torque even thoguh the car feels a good bit better on the street.


Horsepower Graph (http://www.pcmforless.com/images/dynosheets/Cam%20advance/horsepower.jpg)
Torque Graph (http://www.pcmforless.com/images/dynosheets/Cam%20advance/torque.jpg)
Change in Horsepower (http://www.pcmforless.com/images/dynosheets/Cam%20advance/horsepowerdiff.jpg)
Change in Torque (http://www.pcmforless.com/images/dynosheets/Cam%20advance/torquediff.jpg)

Pretty interesting. Looking close at the graph there is surprisingly little change. Nice post, and thanks for the good read.

How about posting your complete setup ?? 494 rwhp and emissions legal sounds good brother. These are SAE corrected numbers too right ??

Alvin, I've seen the same issue with comp lobes. They almost always have 1.5-2.5 more advance in them than I ordered. No big deal with those of us that are checking them, but the guys that are dot-to-dot' ing the install could run into some issues if they are close.

Interesting point on these larger lobes and the .050-.050 routine. I'm degreeing one today on XER lobes and I'll check it at .050, .150, and .300 just for shits and grins and see if the lobe center remains as it was calculated on the .050 number.

How about posting your complete setup ?? 494 rwhp and emissions legal sounds good brother. These are SAE corrected numbers too right ??


Sure

Miezer EWP
SLP Underdrive
Kook 1 7/8 with emmissions fittins and cats
3 inch X with cats
Mid 230's duration lift
Stock Z06 Catback (not sure if thats holdingme back a bit or not)
Vararam
Fast 90
LS2 Throttle body
Trick flow 215's. Compression should be right at 11.2

Is the FAST ported ? As far as your catback, it may be holding you back a bit. LG Motorsports makes a rear section called the big3. Gives you a true 3 inch system. No more necking down to 2 1/2 at the x pipe where it connects to the rear section. Another question, are you still running stock rear end and stock clutch ?? Have changed your flywheel to a lighter weight one ?? Last question, how about a graph, and could you post it. You got one hell of a setup.

If your fast is unported, I think porting it could get you over the 500 rwhp hump, and then some.

Thanks for sharing bro.

Good read. The cam's being off definitely explains why some cars make alot more power than others with very similar setups.

Is the FAST ported ? As far as your catback, it may be holding you back a bit. LG Motorsports makes a rear section called the big3. Gives you a true 3 inch system. No more necking down to 2 1/2 at the x pipe where it connects to the rear section. Another question, are you still running stock rear end and stock clutch ?? Have changed your flywheel to a lighter weight one ?? Last question, how about a graph, and could you post it. You got one hell of a setup.

If your fast is unported, I think porting it could get you over the 500 rwhp hump, and then some.

Thanks for sharing bro.

Its a stock rear end and clutch. It is also the stock flywheel. Back in December this car made 494 rwhp but in the warmer months the best power has been 488rwhp. The fast has been ported.

I think i'd like to try it with a off road H pipe next with a catback exhaust and see what happens. You'll probally never believe me but I have one of the stingiest dynos in this area. This car stock only dynoed 335.

Good read. The cam's being off definitely explains why some cars make alot more power than others with very similar setups.


That was the whole point of this thread. I don't believe the cams are off as much as the old school method of checking for lobe center does not apply with these lobes. I feel like the lobes must be asymetrical to keep the valve train alive.

I honestly believe this cam was very close to right on the money installed straight up even though checking lobe centers using the .050 method said it was 3 degrees too far advanced.

Heres the link to the orginal graph and numbers.

http://www.ls1tech.com/forums/showthread.php?t=854880&highlight=

Really the best thing to do is just check the centerlines and adjust. No need really to degree. 99.9% of cams are correct on the lobes unless you get some junky xxx motorsports cam

All the big engine builders have always said that the Intake/Heads are more than 50% of your HP.

Nice job Alvin. I would rather look at threads like these, instead of hp/trq battles all the time. Good way to show on how cam timing can effect the engines trq/hp curve thru the rpm band.:thumb:

Alvin, I've seen the same issue with comp lobes. They almost always have 1.5-2.5 more advance in them than I ordered. No big deal with those of us that are checking them, but the guys that are dot-to-dot' ing the install could run into some issues if they are close.

Interesting point on these larger lobes and the .050-.050 routine. I'm degreeing one today on XER lobes and I'll check it at .050, .150, and .300 just for shits and grins and see if the lobe center remains as it was calculated on the .050 number.

I would be very interested if you can report back your findings.

Nice job Alvin. I would rather look at threads like these, instead of hp/trq battles all the time. Good way to show on how cam timing can effect the engines trq/hp curve thru the rpm band.:thumb:



No problem. I was interested in seeing the results myself.

Interesting read, thank you.

Surprising results!