5.3 to 5.7L combo help
 

i have an 02 silverado z71 ext cab 4wd... i want to replace the 5.3 for more power and less mileage(175k). i was thinking LS1 shortblock with the 5.3L heads a 98-00 LS1 cam, stock truck intake... ive heard that the 5.3 heads flow as well as LS1 heads and add compression, is this true?? ive seen a few trucks with 4.8L use the LS6 cam and was wondering if that might fit my application and make more power then the ls1 cam. im doing this dirt cheap so used stock style cam is pretty much all i can afford unless i get lucky and find a deal on an aftermarket cam(not likely) i was hoping to reuse the stock converter to keep it simple and save cost as well, im hoping to get 350+ hp @ the crank after i get long tube headers/full exhaust and have it tuned, is this even possible with a combo like this?? any help and suggestions are greatly appreciated i wanna do my homework before i start buying parts

http://cgi.ebay.com/ebaymotors/LS1-C...item41583c71e5


just found this cam, good price, probably sucks though

don't the truck heads lower compression?

I know some of the truck heads flow well, but they need to be milled to get the compression back I believe

General rule is 5.3 heads bump comp and 6.0 heads drop it...

What wrong with the 5.3? High milage is nothing for these motors at all... I know, I had the heads off of a 206k motor and still has cross hatches in the cyl walls.


Reground cams... I wouldnt chance it. As far as use a "stock style cam" IE; Z06, they are very expensive as well... since they work well in an LS1 and are easy on springs and work well with boost.

Why not just swap a 6.0 in the truck? Much cheaper then an LS1...

mileage and cubic inches are the sole reasons for wanting to be rid of the 5.3, and i feel like if i do a head and cam swap, why not swap the shortblock as well... but yes id have np going with a 6.0L if i find one for a good price... if i get a 6.0L and use the stock heads and an LS6 cam would that be around 385hp with a proper tune, headers and exhaust? i really dont wanna buy a torque converter if i can help it as this thing isnt going to be doing much racing i just want more power (like alot more) and i want it to be more fun to drive, as well as be docile enough for everyone else who drives/borrows it(ie wife friends neighbors etc) thats why i wanted to use a stock style cam... maybe LS6 heads as well? wouldnt have to swap springs on the heads id just clean them up and bolt them on... thanks for the help

found through my other thread that the 5.3 isnt worth the time it will take to pull it out of the truck, so im thinking can i do anything with it to get close to 400hp while still being docile enough for the wife to drive?? without spending as much as a 6.0L really wish id have gotten a 6.0L from the factory :-?

Get the heads opened up (the valves are smaller than ls1 stock valves) and add a cam. Also, these trucks (silverado's, yukons, tahoes, etc..) respond very well to tunes. Have you added e-fans yet? You can get a set of efans from an 05+ 5.3 truck and they bolt right in. A few people make harnesses for them that work off the stock computer as long as it's tuned for it. The full exhaust will help as well. There's no reason you can't get close to 400 crank hp with a 5.3 and still be very driveable.

thanks silver, good info on the fans i was planning to use ls1 fans but if the trucks bolt in that sounds good to me i will go look it up now, if i can get 400 out of this thing ill be satifsfied, ill def be getting a custom tune when im done with mods i just didnt think it was economical to have it done x2... btw would a flex fan be of any significant help?

is it true i dont have to take off the intake to do a cam swap on this thing? this is the 2nd LS equipped vehicle ive owned but i only had the simple stuff on my z28 (headers, exhaust, airbox, underdrive pulley, torque converter, diablosport tuner, slicks etc)

i know its for a blower but the specs make it look ok, a little high on the exhuats duration and low on the intake but other then that... if i add a blower later itd work good right ?? lol for $125 if it gives a healthy increase its a steal i cant even find a used cam for that
http://sdparts.com/details/gm-factor...parts/12638427

NP bud. If you need any help or have any questions, shoot me a PM. I've done the upgrade on 3 trucks now and it really is a night and day difference.

getting an entire 6.0 long block would probably be cheaper than ls6 parts on the 5.3. What you are really after(even if you know it or not) is torque. the 6.0 is plenty powerful stock. and you dont really need to mess with converters unless you cam it up. the 6.0 can also run the larger style heads, the l92s or ls3 heads in the future. you should choose your cam after you find out what heads/block you are going with

your absolutely right norseman i am after torque to get the weight moving... but i havent found a longblock very cheap yet, and since the 5.3 isnt worth anything, i might as well mod it, then if i come across a deal on the 6.0 then i can use the heads on the new engine and drop the 5.3 in my firebird lol

found valves, springs, cam and converter from an 05 ls2 for 150... gotta find the gaskets and timing set the cheapest, and find a machine shop that can mill my heads a little, port them and assemble them with the ls2 valves, and i think ill be well under the cost of a 6.0L probably still wont make as much torque as a stock one though lol but like i said i can reuse the heads and all the bolt ons if i ever get one... will this thing run without a custom tune untill i get all my mods done?? or should i just hold the parts until i get everything(headers & exhaust, ud pulley, efans, heads and cam & converter) together and then bolt them on and take it for a tune?

guess ill update this... the cam deal turned out to be a ls1 cam lol... decided to do all the bolt ons sans cam... then build an "Iron LS1" from my block and LS1 pistons... im figuring ill get a higher stall converter now and wait on a cam until i build the 5.7... then everything should work well together and ill get a custom tune and be done, hopefully land solidly in the low 14s and be much more fun to drive... seems like the firebird is going to be jealous of the LS power :-?

CAI, magnaflow exhaust, efans=Check.
few more items in the mail and ill start installing everything... hopefully i can get a "before" track test soon