dyno of before/after 3" cats
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From: Knoxville, TN
dyno of before/after 3" cats First time I ever dynod the car with no other changes then removing the cats. I was surprised that my car ran only about .1 and 1mph quicker in better much weather after a cam swap - went from a 216/220 525/535 114 to a 222/224 566/568 112 comp. Also added a pair of 3" catco cats when I swapped cams to quiet the car down and make it smell better, Tuned it on the dyno and made a respectable 417/385 a couple months ago so I was happy..
Went to the same track I ran the 11.86@117 (1.727 2800' DA) at with the smaller cam in the summer last friday and the best I could do was 11.77 @ 118 (1.720 900' DA) so I'm like wtf. Dynod the car saturday and it did 408/380 which isnt horrible, I had since added a steel driveshaft and some heavier wheels/tires on the rear + diferent day dyno error so I didnt think it was too far off. Decided to pull the cats and see how much they were costing me, no changes on the car at all, all I did was take the Y-pipe off and punch the cats out Sunday then dynod it yesterday. Similar temp in the shop, identical a/f.
I'd say they were costing me a bunch, not so much peak but under the curve. I went the cheap route with the cats but I may try some of those metallic cats if the price gets more realistic..
Went to the same track I ran the 11.86@117 (1.727 2800' DA) at with the smaller cam in the summer last friday and the best I could do was 11.77 @ 118 (1.720 900' DA) so I'm like wtf. Dynod the car saturday and it did 408/380 which isnt horrible, I had since added a steel driveshaft and some heavier wheels/tires on the rear + diferent day dyno error so I didnt think it was too far off. Decided to pull the cats and see how much they were costing me, no changes on the car at all, all I did was take the Y-pipe off and punch the cats out Sunday then dynod it yesterday. Similar temp in the shop, identical a/f.
I'd say they were costing me a bunch, not so much peak but under the curve. I went the cheap route with the cats but I may try some of those metallic cats if the price gets more realistic..
Last edited by kp; Oct 29, 2003 at 12:40 PM.
