Another cam test and some adjustable gears
Two weeks ago I tested a new custom ground cam we had done. The results are not what I expected. Over that weekend I got to thinking about how the car was running and determined something was wrong with the car. The following Monday I came in and found that something was wrong with the COP. I fixed it by replacing everything and then took the car off the dyno.
I wanted to go back and test the cams again so today was the day. First thing was to determine what the original problem was and I found it. NOTE TO SELF: "Do NOT do your own wiring on a COP." I screwed up the harness on the COP and that's what was wrong. Fixed, put our production wiring kit on the car
Next up was to run our 272 cams in the car. I made a few pulls and then started moving the sprocket around. The first test was to advance the intake cam. I advance the cam by 4 degrees. The car's idle was noticably worse. The power did increase in the low/mid range by a nice portion.
Down low the gains in torque started at 3400 rpm and were up 2 ft lbs, at 3700 it was up to 27 ft lbs by 4800 rpm they peaked at 34 ft lbs and then slowly fell off until at 6000 rpm the torque was equal again. This slowly turned into a max loss of 7 ft lbs at 7200.
Down low the gains in whp started at 3100 rpm up 1 ft lbs, at 3700 it was up to 19 whp and by 4800 they gains peaked at 32 whp and then slowly fell off until they were even at about 6100 rpm and then slowly became losses with a peak loss at 7200 of 7 whp.
The next test was to put the intake cam back to 0 and then advance the exhaust cam 4 degrees. This resulted in nothing but losses.
Next up I retarded the exhaust cam 4 degrees, there were no gains/losses over running the exhaust cam at 0.
Here is the dyno sheet showing the cams run at 0, intake advance 4 degrees/exhaust 0 and intake 0/exhaust retarded 4 degrees.
This tell me that installing our cams advanced slightly on the intake side, if you can stand the idle being worse, is a good trade off for some additional low end/mid range with slight losses up top. This can be done by installing the cam a 1/2 tooth advanced on the intake cam if you don't want to buy sprockets.
Next I swapped the new custom grinds in the car.
The idle is very good on the custom cam. The power was also very good, compared to our cams the peak whp/torque were basically identical. There were some losses in the low/mid range.
Next was to try to advance the intake cam by 4 degrees, this brought the low/mid range up to match our BF272's, the charts like this are identical. I did a few more tests but the next one on this sheet is the intake cam advanced 4 degrees and the exhaust cam retarded 4 degrees. Retarding the exhaust cam made the car so it would barely run at idle. The power was identical with the exhaust cam retarded, just as I found it to be on the BF272's.
Here is the dyno graph comparing the large came set at 0, then set at 4 degrees advance on the intake, then 4 adv int/4 retard on the exhaust:
What did I gain from all this? Not much, just as I've found in the past. I spent 6 hours on the dyno today, put I-don't-know-how-many more runs on my car and beat the shit out of it for basically nothing.
Yes, the 30+whp/ft lbs on both cams in the low/mid range is a nice gain, I can't deny that. Simple enough to do, move the intake cam gear half a tooth.
The bottom line is for power over about 5800 rpm both our cams and these custom ground cams performed best set straight up on the stock cam gears...........intersting isn't it.
Enjoy the test.
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Originally Posted by warp9
