Greg5OH

First off let me introduce myself, all I know are ford engines, idi, psd, sbf.

completely new to working on chev engines. Not new to building fords.
That said, I know the LS are the best bang for the buck.

Picked up an 07 5.3 LS complete with ECU for $350 off a coworker from a 1500. They pulled it because it was "ticking" replaced rockers but its still there. Plan on opening it up anyway.

This will be going in my 1993 foxbody backed by a t56.

Goal is 400-450 rwhp, 6500-7000 rpm, great throttle response, mid to hi rpm range hp peak. This is is a street/track car.

I love lumpy, snotty, gnarly sounding camshafts. Will be doing alot of research, but as a ball park/general info looking for a quick breakdown what I need to reach my goal?

valve springs-z06 or some comps?
What type of cam? Will hydraulic cam and stock style valvetrain support what I want? Seems alot of people go with Texas speed cams?
better pushrods?
better rod bolts/studs?
long tube headers are a must,
what intake?
TB?
and a tune for sure.

Thanks for bearing with me.

Mercier

iTrader: (15)

That's the upper end of potential for a 5.3. Consider that the 5.3 can be bored right out to 5.7 with used LS1(5.7) pistons and I think you are in a more comfortable pistion to reach your RWHP goal.

Probably just a sticky/clogged lifter. LS7 lifters are $100/set.

What heads do you have? If 243/799 you might be able to make it.

Seems like I post this once a week..going to have to send Car Craft a bill for the marketing..

http://www.hotrod.com/how-to/engine/...st-comparison/

That will give you an idea of what an early-ish 5.3 can do with various factory and a couple of aftermarket cams.

Let us know what heads you have and we can go from there.

Greg5OH

Thanks Mercier. TBH id like to keep it stock bore just to keep the cost down. As for the heads, the two numbers you provided, are those two different heads, or is that one part number? is this something that will be stamped in the back or rear side of the heads?

Also I am mistaken, it is an 06 engine. 70k miles on it. I too think it is a lifter.

question regarding that hotrod article. There are a bunch of different engines wqith larger displacements shown. in the comments, for example ;
Despite similar specs to the LS2 (increased intake lift), low-speed power production with the LS3 cam was down compared with the LS2. This was evident from the fact that the LM7 offered more torque up to 4,200 rpm. As expected, the LS3 offered plenty of power, producing 405 hp and 398 lb-ft of torque. This represented a peak gain of 91 hp over the LM7 at 6,500 rpm. We expected the additional lift offered by the LS3 grind to increase power over the LS2, but that was not the case on this application.

does this mean the used the LS3 cam in the 5.3 LM7?

Mercier

iTrader: (15)

The article mentions the displacements of the engines that originally came with those cams but all cams and power numbers mentioned are with the same LM7(5.3) engine. Also the numbers are at the crank and not wheels so keep in mind wheel numbers are lower.

799 or 243 would be found on certain heads but not both on the same head. Have heard stories of mismatched heads from the factory. 799 and 243 on a truck are basically the same casting so this really isn't a big problem. See below for a picture of the stamping you need to find on yours:

http://www.ls1truck.com/forums/sale-...eads-sale.html

The "243" on the end of the head is what you are looking for. You also might see 862, 706, and several others.

Greg5OH

I got 706 heads

Mercier

iTrader: (15)

706 is practically identical to the 862 used in the article. 862/706 have a slightly smaller intake valve(1.89" I believe) and a smaller combustion chamber than typical LS1 heads. If you will have the heads off, you could mill them to bump compression and then get some LS1 valves(2"). I priced milling and having the seat opened up on a pair of 862s and it was about $75/head.

Info on stock heads:

http://houstonperformancetrucks.com/...h-flow-numbers

There is also some evidence of 706 heads by Castech having cracking problems. I think this was gone before 06 and I have no hands on experience. Google "castech 706 crack" or similar and judge for yourself.

Greg5OH

thanks. I figured its a lo-po engine compared ot LS1 stuff. I just dont want to get into resurfacing heads, rocker sweep patterns, cutting new vlave seats, new vlaves etc. Usually money and time ahead buying better heads-but again, dont necessarly want to do that as Im trying to keep this a budget build. But I am open to ideas.

If a head swap to LS1 heads is budget friendly (i see 706 heads for 150 a pair all day, can i get ls1 heads for aroudn 300 a pair?). Better heads = better cam than can take advantage of the flow, and a nice intake and exhaust.
Would I be money ahead by buying complete ls1 heads? or can I get some decent power numbers using my stock 706 heads just cam intake, exhaust and porting by a pro? (coworker does great porting work for a friend price)

I guess I should tame down my power goals too, 450 horse at the wheels would be like 500-520 with 15-20%driveline loss. I guess 400-450 at the CRANK might be more realistic?

Mercier

iTrader: (15)

Stock LS1 heads will cost you in compression so those would need milling. We're talking .030" or so and I don't think you'll have to worry about wipe patterns. 243s are the best factory cathedral port heads and can be had for $400-$450. They have smaller combustion chambers than the LS1 heads but larger than 706 so would still want a slight mill. Outside of the 243s, the port design of the 862, 706, 853, 241 are similar so short of valve and combustion chamber differences, have the same potential. Ported 243s are still said to be worth 5%-10% over the other heads ported but that's about it. They are probably 20% better in stock form.

LS1 and 5.3 heads are maybe worth $150 for a nice set.
Basically you've got small chambers and 1.89" intake valve. 243/LS6 heads, larger chambers, 2" valves, better port design. LS1 heads, largest chambers and 2" valve and same basic port design you already have. 400-450 crank is still on the big end for a 5.3 so you are squarely in 2" valve territory IMO.

Porting 706s will produce nice flow numbers but you'll want to go with bigger valves at the same time. Keep in mind you are bore-limited to 2" intake valve on a 5.3. You'll start with the smallest combustion chambers and could mill a little yet and get your compression up even more.

redtan

iTrader: (5)

400 to 450 is a huge range for a 5.3 and will require significantly different levels of parts.

400rwhp can be attained with some milled 243 heads and a decent cam plus an LS6 intake.

450rwhp is going to require a much more radiacal cam, ported 243s or aftermarket heads and most likely a FAST intake and bigger injectors.

Mercier

iTrader: (15)

I think OP has reset expectations to 400-450 crank. You are right, 450 @ wheels is pushing it for a 5.3.

redtan

iTrader: (5)

Ah sorry missed that last edit by him.

360rwhp should be easily attainable with a cam in the low 220s and some basic 243 heads with an LS6 intake. You need the basic cam kit, oil pump, timing chain, lifters, headgaskets along with the usual exhaust and air intake mods.