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What a 258 can handle (soon to turbo) |
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farna
Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19686 |
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Mid 70s 258s were 8:1 compression -- 72-78. 71 models had 8.5:1.
I found one article with a 71 Gremlin with a 258 running 8 psi. I wouldn't run that much, only 5-6 with stock pistons and trans, but he's been running fine for years (and states that the trans is a weak point, but uses a BW M4x that was made for a 304). States he has no spark control, but runs premium fuel and a Holley 500 2V carb. This is a "semi remote" mount (turbo on right side with pipe run from exhaust manifold under engine) blow-through setup and what I'd recommend -- has to be the easiest way to do it. http://gremlinx.com/1971-turbo-gremlin/ Found a "Hot Rod" magazine article on the 1977 Randal AMX turbo six. They test drove the prototype 10 psi boost car. They state the stock trans wasn't up to 10 psi boost, so Randall dialed the "production" setup down to 5 psi -- 3 psi was in by 1800 rpm, all five by 2500. Randall modified the end of the stock exhaust manifold to mount the turbo flange on the left side, and a draw-through Motorcraft 2V (370 cfm -- 1.23 venturi is 356 cfm, closest, next larger size is 1.33, rated at 424 cfm). The article does say the carb was modified, but a 356 cfm should do the trick. Seems the 77 kit is the only Randal turbo six offering, 1977 only. http://clubs.hemmings.com/classicamx/turbo-hornet/turbo-hornet.htm |
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Frank Swygert
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DaemonForce
AMC Addicted Joined: Jul/05/2012 Location: Olympia, WA Status: Offline Points: 1070 |
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That actually sounds more than reasonable for daily use. The way my
stroker is setup, it uses the factory 258 crank so it shares the same
rev behavior as that engine. My tall gearing with the Chrysler automatic
and mild cam would be fine. Those 2.72 to 1.55 ratios has me looking at
my first shift around 2625 and 2-3 shift at 2325. Since my T-5 has been
swapped in with a wide spread arrangement, those steps are 4.03 to 2.37
which puts me in exactly the same range as the auto. 1-2@2550,
2-3@2375, 3-4@2250. These figures would be much higher when doing a
launch but you get the idea.
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1971 Javelin SST
American 304 2v | FMX | AM20-3.31 1983 American Limited Jeep 4(.7)L S-MPFI | 1982 NWC T-5M (4.03/.76) | Dana30IFS/35-2.72 |
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