Guess my horsepower
 

So I recently did a tranny swap from a m6 to a 4l80e with a 3200 stall. At the same time I also did some prc cnc heads milled .20. Originally with the m6 the car made 725 rwhp. On the same dyno with the new setup it made 640. Does this sound right? Do u lose that much thru an auto? Any comments welcome! Thanks

Yup especially with that trans

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Surprised u didnt do a 6l80e

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you swapped from a M6 to an auto on purpose? Did you lose a foot in a freak accident (if so, my apologies) if not................ :/

Which is better, auto or manual? :iono:

It would depend on what a person intents to use the car for. If you`re a serious drag racer then you probably should be using an auto that`s set up and modified for the strip, if it`s a daily driver then it really doesn`t matter what your preference is.

I love my 850hp auto

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And I love my 400HP auto. Beats the hell out of every factory auto I owned prior. Love is subjective.

6L80 loses about 22% from crank to rear wheel. Not sure on the accepted numbers on a TH400.

22% is inaccurate, more like 15 to 18

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A th400 is more than a 6l80 and heavier and on avg is 100hp less than a 6l80

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The L99 was rated at 400 crank hp and most of baseline dyno pulls show 307-315rwhp. 22% loss would be 312rwhp. I’ve been told 20-22% by many on here with the 6L80. “Common knowledge” guesstimate used to be 15%, but that seems generous by the graphs I’ve seen.


Edit- I can’t find the post, but I believe Ted Janetty said he was getting 460-ish rwhp from a stock auto ZL-1. While not quite the same trans as the SS, it’s still in that 20-22% band. Using 15% would put my car at 455hp, which is extremely hard to believe based on mods and seeing other cars run on that same exact dyno.

Wow, cant argued there, i took my l99 out and went 408 stroker iron block with 10 rib maggie

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That’s a great place to go with a L99!!! :)

I hoping to do a cam next.