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408 power


zippy

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well i finally got to drive an SS with a 408 in it. i must say it was a damn nice driving setup. me and a couple buddies drove down south and picked up another members truck to finish some work on it. the truck has a fresh 408 in it that hadn't even been on the road yet. i only got to put about 200 miles on it before the damn trans let go. :banghead::banghead::banghead: oddly enough i hadn't even been runnning it hard and on top of it when the trans broke it did so with the cruise set at 70mph. i must say the fuel milage was extremely impressive. i'd have to guess at this point without having been able to run a full tank through it that the 408 was getting better fuel milage than a stock SS. the fuel milage was just outstanding to say the least with the small cam in it. the extra stroke certainly shined in low end torque. i couldn't run it hard at low speed because the bed was loaded, but even with the bed of the truck loaded enough that the truck was hitting the bump stops over even mild bumps, it had more than enough torque to pull up some serious hills in overdrive with the converter locked in. i think someone at gm needs to take a drive in one with a mild built 6.7L and they'd see that it's just how the truck should come...

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a 402 or a 408 has always been in my plans for my C3. The wait is tough though :D

I'm thinking a 409 myself. Or at the last moment I might just say f-it and do a 434. To Rev or Not To Rev, That Is The Question... :jester:

 

oh why stop there? be a trendsetter with something nobody else has done? :jester:

 

me, I'm only looking for 450hp/500tq normally aspirated. lots of grunt and all done by 6k rpm. :lol:

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The mileage on my first go around on a 408 was much better than stock. Even with the condition of tune, I was getting in the very low 20s on the highway with cruise set at 70. Don't think that will be the case with my new setup.

 

The setup you were running has the stock intake and exhaust valves, w/p&p heads, right?

 

Low-end torque is awesome. What CR is it at?

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oh why stop there? be a trendsetter with something nobody else has done?  :jester:

 

me, I'm only looking for 450hp/500tq normally aspirated. lots of grunt and all done by 6k rpm.  :lol:

You want the big-arm then (408), stock-length rods, LOTS of port, and moderate cam. :D I'm thinking of shifting somewhere around 6600 (wahahahaha) in first but I need to ask Joe how much RPM his tranny can take.

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... I was getting in the very low 20s on the highway with cruise set at 70.  ...

Holy cow, I'd have never guessed the mileage would be that good.

That was even with what comes out to be 72lb injectors with my increased fuel pressure and running an excessively rich tune.

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the truck is matt's truck (mwalls54). if i recall the compression is around 11.7:1. the heads are stock with 918 springs and the cam is the same as he used with the 6.0L. if i recall it's 212/218 and .522/.529. once i get it dialed in the new heads and bigger cam will go in. even with the stock heads and very mild cam it didn't seem to lack power anywhere.

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the truck is matt's truck (mwalls54). if i recall the compression is around 11.7:1. the heads are stock with 918 springs and the cam is the same as he used with the 6.0L. if i recall it's 212/218 and .522/.529. once i get it dialed in the new heads and bigger cam will go in. even with the stock heads and very mild cam it didn't seem to lack power anywhere.

 

The cam is actually a little bigger than that. I dont have the cam card with me right now. The cam that is going in is a very healthy size. I am glad it runs good :tear::tear: I just wished i got to drive it :tear::tear:

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i would have to say the cam and heads will be the biggest difference in fuel milage. i'd really like to try to get the trans fixed next week and run it on the dyno with the stock heads and this mild cam.

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