71gibby Posted September 21, 2017 Share Posted September 21, 2017 Looking for some input on the 8.2" rear end currently in my 72 MC. My plans are to build nothing more than a street car with some "get up and go". It will never be on a drag strip or race track. The plan is to install an engine within the 400hp range and 200-4r/700-r4 overdrive transmission with a limited slip differential. The question is: Will this 8.2 hold up or am I needing to source an 8.5"? Been to a few swap meets/Craig's List etc. and have run in to problems finding an 8.5" and am kinda running out of energy and want to get something back under my chassis. Thanks for any and all input! Jim Quote Link to comment Share on other sites More sharing options...
Leghome Posted September 21, 2017 Share Posted September 21, 2017 I have an 8.2 in my 72 but I am only running about 330 horse. It is Richmond 3:73 posi geared and works great with my 700r4. Quote Link to comment Share on other sites More sharing options...
Trueblue Posted September 21, 2017 Share Posted September 21, 2017 Tagging in for future reference Quote Link to comment Share on other sites More sharing options...
cbolt Posted September 21, 2017 Share Posted September 21, 2017 My 8.2" setup is dyno-d at 300 to the wheels and I am running an Auburn gear limited slip and 3.73 Richmonds behind a 200-4r without issues. Quote Link to comment Share on other sites More sharing options...
71gibby Posted September 22, 2017 Author Share Posted September 22, 2017 My 8.2" setup is dyno-d at 300 to the wheels and I am running an Auburn gear limited slip and 3.73 Richmonds behind a 200-4r without issues. Thanks for the reply. Sorry to ask this but, if you are 300 at the wheels what are you out of the crankshaft? I know there are losses but do not understand how much is lost through the drive train. On another note, did you upgrade your axles or are they stock? Thanks! Quote Link to comment Share on other sites More sharing options...
cbolt Posted September 22, 2017 Share Posted September 22, 2017 I have no idea what my motor is rated at the crank. I have a buddy with a dyno shop, so we ran it 7 times to get it properly dialed in. I did put new axles in, but nothing fancy. Just new axles because my original ones were pitted in the seal area. To be fair I didn't build a race car so I don't test the setup too often. Quote Link to comment Share on other sites More sharing options...
GatorDog72 Posted September 22, 2017 Share Posted September 22, 2017 I usually figure about 15-20% drive train loss with an automatic transmission. 300HP at the wheels would be about 345-360HP at the flywheel. Quote Link to comment Share on other sites More sharing options...
71gibby Posted September 28, 2017 Author Share Posted September 28, 2017 Thank you for all of your input! Jim Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.