Which heads?
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Which heads? A 2004 5.3 with the 706 heads, stock bottom end with the stock slightly dished pistons. I have acces to some 799 heads which flow better but have a bigger chamber so the compression will be down to about 8.8-1. Will this work good for a turbo setup?
If you have the budget, take the 799s to a machine shop and have them milled. If I had thought of it when I put 243s (same as 799s) on my LS1, I would've had them milled some.
I know there are guys with 243s milled .030" on 5.7L or bigger. Should be fine on a 5.3.
The 5.3 heads flow like crap unless heavily ported. You'd have less money in having the 799s milled, and you'd still have room to have them ported in the future, if you desired.
I know there are guys with 243s milled .030" on 5.7L or bigger. Should be fine on a 5.3.
The 5.3 heads flow like crap unless heavily ported. You'd have less money in having the 799s milled, and you'd still have room to have them ported in the future, if you desired.
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My goals are to may as much power I can on a stock bottom end up to about 15 plus lbs of boost at the track and limit it to 8 around town. I'm pretty new to my area so I'll have to find a machine shop
I would definitely vote for the 799s. Making power is all about flowing efficiently and the 799s do that very well unported. Find a reputable shop in your area and take the heads to them. It can't give you an exact quote, but I'd guess a mill job would run about $150.
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Thanks. I'll look for one, I'm new to this whole turbo thing. I know an old school supercharged big blocks you wanted a lower compression ratio, is it different for turbo motors? Or is it for the overall drivability and electronics of the LS family of motors
It's the same idea for any forced induction motor, doesn't matter what is creating the boost. The lower your static compression before boost, the larger amount of boost you can squeeze in *safely* and still remain on a lower, less expensive fuel without detonation under boost. There are exceptions to this, but with you not going for an "all out race motor", no need to explain lol
If I were to build a turbo motor, I would aim for 9.5-10.0:1.
If I were to build a turbo motor, I would aim for 9.5-10.0:1.
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Haha I figured it was the same. Thanks for the info, I really appreciate it. Plans for the motor are a custom cam, head studs/good gaskets, a pair of 58-62mm turbos through an air to air intercooler. I haven't figured out what to use for an intake yet. Should be a fun car, hoping to go 10.0 Car weighed 3120 with me and big block in it
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On The Tree
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It's more of limiting to what the stock bottom end will handle at the track. I've been reading for months on doing this and finally pulled the trigger and picked up a complete motor. I'll check the ring gaps and open them up if needed I don't want to spend a ton of money on the bottom end till I have this turbo thing down and find a good tuner in the Maryland area
That's a great plan. Get all of the little bugs worked out before you rebuild the motor. Once you decide to do the bottom end work, you can always send those 799s off for CNC porting as well.
With SBE, I'd say 15 PSI is a good limit for now. Once built, the boost can go up and those heads will really show.
Not sure where you are in Maryland, but with MIR being such a popular track, I'm sure there are some reputable shops and tuners in the state.
With SBE, I'd say 15 PSI is a good limit for now. Once built, the boost can go up and those heads will really show.
Not sure where you are in Maryland, but with MIR being such a popular track, I'm sure there are some reputable shops and tuners in the state.
.030" is a very popular amount from what I've seen. 243/799s are around 64cc stock, and 5.3L heads are 61.1X cc. You shouldn't need to mill them .030" to get back to stock compression, but it is an option if you want to go closer to 10.0:1. Just search around a little about what people have milled their 243/799s to. I did a quick search and found a thread about a guy who milled his .075".
If you get the 799s milled to match stock compression or go a touch higher, I think it will be worth every penny. Stock 5.3 heads are crap, and you'll have room for port improvement in the future with the LS6 heads. In my mind, its no question. With a custom grind, your cam will outflow your stock 5.3 heads, rendering it pretty much useless. You gotta have the cam, heads, and intake to all match to get the best results possible. The custom grind will match the 799s much better.
Do you have flat top pistons or dished? 2004 5.3's came with both. If it has flat tops I'd go with the 799's personally. Much better head... Also how are you calculating compression? 8.8 doesn't sounds really low to me.
Are you planning on taking the heads off to replace gaskets or head fasteners? If so I'd run the better heads.
Compression does diddly IMO. I'd rather have the good head. I ran Gen3 dished pistons with the larger CC 317 heads was around 8.6:1. With the right converter/setup I didn't even notice the lack of power NA. That combo went 8's on a factory cam @ 3000lbs.
Are you planning on taking the heads off to replace gaskets or head fasteners? If so I'd run the better heads.
Compression does diddly IMO. I'd rather have the good head. I ran Gen3 dished pistons with the larger CC 317 heads was around 8.6:1. With the right converter/setup I didn't even notice the lack of power NA. That combo went 8's on a factory cam @ 3000lbs.
Last edited by Forcefed86; Jan 4, 2017 at 10:23 AM.
Turbo Head Flow Balance = 90% Hi Nova, your head choice should be MORE directed to the BEST exhaust flow.
I am not an expert on the 706/799 head, I would pick the one with greatest exhaust port.
I would install an exhaust valve that is larger and made of better material.
I would have the exhaust "ported" and the intake "blended" ONLY.
My best luck is a Z-06 OEM camshaft, Chev-Hi article, for your guessed requirement. (1220 HP @ 22 .lbs, Westec Benched)
I would fit a Truck Intake, a FelPro 1041, Chinese Studs, Camaro 2010 OP,
IwIs single chain, Denso injectors, Yellow springs.
These quality low cost items will save you money, money for Forged Pistons.
I found that you want to "open" the engine, if so, I would be able to supply a Ractac piston, rings, .927" pin. for $650.00 at your door.
Would you like more information ?
Lance
I am not an expert on the 706/799 head, I would pick the one with greatest exhaust port.
I would install an exhaust valve that is larger and made of better material.
I would have the exhaust "ported" and the intake "blended" ONLY.
My best luck is a Z-06 OEM camshaft, Chev-Hi article, for your guessed requirement. (1220 HP @ 22 .lbs, Westec Benched)
I would fit a Truck Intake, a FelPro 1041, Chinese Studs, Camaro 2010 OP,
IwIs single chain, Denso injectors, Yellow springs.
These quality low cost items will save you money, money for Forged Pistons.
I found that you want to "open" the engine, if so, I would be able to supply a Ractac piston, rings, .927" pin. for $650.00 at your door.
Would you like more information ?
Lance