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408 power


zippy

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I've got an Avalanche with an LM7 (5.3L/325ci) motor, so I'll need new heads as well.

Yeah that would be a great upgrade, your Av probably has better gearing, too. Put a stump puller in that truck, shift just short of 6-grand; fun for the whole family! :D Does the 5.3 use the 6.0l intake?

 

Mr. P. :)

 

I've got the same gearing as you guys....a 4L65E tranny and 4.10's in the back (the only mod I wish I hadn't done....swapping out my 3.73's.....they had better mileage and better freeway behavior :( ).

 

I believe all the truck intakes are the same (4.8L, 5.3L, 6.0L).

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for your application kevin i'd recomend just going with a set of stock or very lightly ported heads. opening them up much is going to move the powerband up and may work into poor fuel milage as well as emissions issue's. you'll have the boost to force the air in there. with the 402/408 combo and a 2.8 pulley from LPE you'd have a great combo in your AV. just keep the cam small or the radix will be useless.

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I remember that Av on here awhile back

 

A 2003 Chevy Avalanche sporting a 540cid big block chevy

with twin supercharged water-to-air intercooled 4-wheel drive

that makes 890ftlbs of torque at 2300rpm.

 

that thing was Bad Arse!

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for your application kevin i'd recomend just going with a set of stock or very lightly ported heads. opening them up much is going to move the powerband up and may work into poor fuel milage as well as emissions issue's. you'll have the boost to force the air in there. with the 402/408 combo and a 2.8 pulley from LPE you'd have a great combo in your AV. just keep the cam small or the radix will be useless.

Cam small, as in..............???

 

Any suggestions as to where to get a set of stock heads?

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for your application kevin i'd recomend just going with a set of stock or very lightly ported heads. opening them up much is going to move the powerband up and may work into poor fuel milage as well as emissions issue's. you'll have the boost to force the air in there. with the 402/408 combo and a 2.8 pulley from LPE you'd have a great combo in your AV. just keep the cam small or the radix will be useless.

Cam small, as in..............???

 

Any suggestions as to where to get a set of stock heads?

here, LS1tech, ebay,......

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I remember that Av on here awhile back

 

A 2003 Chevy Avalanche sporting a 540cid big block chevy

with twin supercharged water-to-air intercooled 4-wheel drive

that makes 890ftlbs of torque at 2300rpm.

 

that thing was Bad Arse!

:lol::lol: That thing was a f-ing ANIMAL! :D

 

Mr. P. :)

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for your application kevin i'd recomend just going with a set of stock or very lightly ported heads. opening them up much is going to move the powerband up and may work into poor fuel milage as well as emissions issue's. you'll have the boost to force the air in there. with the 402/408 combo and a 2.8 pulley from LPE you'd have a great combo in your AV. just keep the cam small or the radix will be useless.

Cam small, as in..............???

 

Any suggestions as to where to get a set of stock heads?

 

 

i may have a set to sell here in the near future if the other set matt bought are ready to go. otherwise i'll be porting these and putting the patriot valve springs on myself.

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well, the trans is back in. the new vigilante converter and billet servo's were also put in with it. i'll probably drive this one tonight for a bit with the laptop to get some logging and tuning done. from what i understand there will be no open dyno at w2w next week so the odds of me getting it dyno'd then are slim. i'll have to pick another day in the future since i'll have to take a day off work just to go out there and dyno it.

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well, i've been out running the truck around. can't seem to get it to use any fuel. if i were to go by the reading on the cluster it's showing a 17.8mpg average even with tuning w.o.t. runs. if i had to guess i'd say it's real close to that. probably around 16mpg or better. there is a little bit of highway and backroad driving that helps the milage, but there is some wide open runs in there also. the power at low rpm is just outragous for something not running boost. up high it pulls well, but isn't showing impressive numbers through the maf considering how hard it pulls. it's very efficient on what it's doing with the air it's taking in. at this point i've only seen 37lbs min. at the maf, but as tuning goes on it keeps going up. it was only pulling 32 when i started. i'm expecting it'll pull around 42lbs min by the time it's broken in and fully tuned. there are some cammed 6.0L engines out there that have pulled that number, but this will pull that number by 4500rpm and hold it over 35lbsmin to the shift point. tomorrow i plan to put the wideband on it and get the a/f where it needs to be now that i've gotten it roughed in. hopefully wednesday i can make a pass with it at the local dragstrip for some early testing numbers. i'd guess that with ported heads and the bigger cam there would be a solid .7 sec gain to be had. on the other side though it has the powerband of a stock 6.0L, idles at any rpm you put it at smoothly, and wouldn't care how big of a trailer you hooked to it was. this is just how the SS should have came.

 

as for the dyno run, i'm still not sure when i'll be able to get time off to get back out there to dyno it. next week when i go to wheel 2 wheel there won't be an open dyno that i know of unless i can somehow bribe kurt to get me in. maybe if i showed a response on how many people wanted to see a dyno run (true awd dyno) of this 408... how about it guys, post away.

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