Quote:
Originally Posted by 392cobra
Stock/standard exhausts will drive the losses up that high.
You can't expect to get good rwhp numbers with low losses from the crank without a special effort put into the exhaust.
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If you don't dyno with the equivalent or entire vehicle exhaust system you are not going to get accurate in-car results and a correct tune. I know that is difficult but not impossible especially with the outside systems used. I have dynoed all my engines this way and it translates well to rear wheel numbers IE 15 to 17% loss. The fuel air ratios, cam timing and ignition timing are also much closer to ideal. You could also do most of the tuning on a chassis dyno but changing cam timing can be a challenge in the chassis.