I am a newbie to vetted having lusted for one for57 years to finally get mine, a 2003 coupe with an LS1 and auto trans.

I would like boost the performance a bit without going wild but I am on a reasonable budget. I expect to drive primarily on the street. What I would like to get your input on is regarding which upgrades you suggest to add, and the sequence they should be done in. The would like to add about 75 horses.

Thanks,

Gary

 

Depends on what gears you have. If 2.73 I'd switch a 3.42 rear (any manual tranny C5) before any other mods. While you're back there maybe a slightly higher stall converter.
Otherwise, specifically for 75HP... hmm... headers, CAI, cam (pick a vendor, tell them your goal), used 243 heads. Easy 425.
Hard to pick tho without some idea of your budget.

 

75HP is easy. If you do all the mods at once there will be less redundancy in labor. It is more cost effective with less down time.

The 243 heads and the 799 heads are the same casting. The 799 heads are rough cast in Mexico and don't have the sodium valves. They are more available and less expensive.

I would go with a LS6 or better cam with new lifters and the recommended valve springs.

A cold air intake and a freer flowing exhaust and a tune. A tune will really wake up your car (especially the automatic trans).

If you have 3.15 gears you should be fine depending on your goals.

 

CAI, LS6 intake, Hinson longtubes with a stock TI exhaust and a tune.

For a feel of the seat of your pants I'd consider adding a stall.

Also not all the 243s have sodium valves so if you were going to go to a heads and cam setup the 243s found on the newer 5.3s can also be sourced for cheap. $375-400.

I suggest doing the bolt ons first that will of course cost less and have less labor involved and will give you an idea of the new found power. The jump to heads and cam even stock stuff will jump the cost double fold

 

The OP has a 2003 so he already has the LS6 intake set up. If he can do the work himself then the cam and heads can be done for around $1,200 Using the LS6 cam. That includes lifters, springs and gaskets. You can go with .040" head gaskets for higher compression and better quench (good for a few HP). It is a good Idea to replace the harmonic balancer at this time as the stock ones are known to fail. While the heads are off you may as well add headers if you are going to because it would be a lot easier with heads off. You can go with OBX headers if you are on a budget for less than $500.

I agree with the above poster about using the Z06 titanium exhaust. You can get low mileage ones for less than $500. The exhaust has to come off to replace the torque converter or diff. Torque converters are highly subjective. A higher stall converter will cause the trans to run hotter so it is a good idea to use a trans cooler. I would add the trans cooler while the radiator is out (when you do the cam). Higher stall converters are good for straight line performance but not so much for road racing. They allow you to get up to a higher HP range for launch. If you do get a converter get the best one you can. This is not a place to try to save money.

The CIA can be as simple as the zip tie mod and K&N filter.

You can send your PCM for a mail order tune to get all of this to work (about $150).

I think this would make closer to a 90HP+ gain with no downside. Near perfect street manners.

 

If you just bought the car I would drive it for about 2-3 months before I spent any money on mods. The reason I say that is you don't know the car that we'll yet and you never know what you will find out. You may find that there are a few maintenance items that need attention or maybe you decide you are happy with the power output but you want it to handle better.

 

It's a good idea to completely check out the condition of the car so that you get a good idea of what may be needed to better handle the HP increase you want.

Brakes and suspension are two areas that really have to be in good shape once you start to up the power levels. Tires are another thing to consider. How old are the tires and how much tread is left? What's the mileage on the car now? High mileage may cause you to look at doing a complete rebuild rather than just cam and heads

You said it will be "primarily" for street use; what other types of activities are you interested in just "spirited" driving, autocross, track days, drag racing??

 

Other than street driving I might be doing grudge drag runs, or beating those smart as- little Mustang kids. Nothing sustained hard type driving. In the future I may get into other things but not for a while.

 

I tore my engine down after 130,000 miles and all of the wear surfaces were near perfect. Others have had similar results. These engines were engineered well. I wouldn't sweat the engine internals much unless it is super high mileage.

If you replace the cam I would replace the timing set, balancer and oil pump. If you replace the heads I would replace the lifters, push rods and rockers.

A tune alone will really wake that A4 trans up.

 

Mine has 84k and so far runs and sounds great.

Thanks

Gary

 

Very good information by all. Going to keep this in a Word document for future reference.

 

Please send me a copy of the Word doc when you have finished.

Thanks

 

2002-2004 LS6 cam

243 or 799 heads

Z06 or truck 85MM MAF

Air intake(Vararam, Blackwing or the like)

1 3/4 headers

Catless X pipe

Z06 Ti catback

Tune

Car will drive like stock and make 100 more HP than stock.

 

I just purchased a Vararam intake, but my questions right now are:

1 - Should the LS6 cam be installed with different lifters, rods, etc?

2 - Should I wait to install the new 85mm MAF until I change the heads and cam, or is it ok to install these items as I can obtain them?

3 - I know a tune is very important but are there any of you suggested items not dependent on a tune after installation.

I look forward to your response.

Thanks

 

1. The new lifters with trays are not expensive, an improvement, and good insurance. The little bearing on the lifter goes through a lot in its life and need to mate up with the new cam. They are called LS7 lifters. ~$100.5

The LS6 cam has a .025 undercut base circle and this will need to be compensated for with longer push rods or LS6 valves. A lot of times rebuilt heads are resurfaced .0035" or more and valves resurfaced. Mine were planed .007", Valves reseated triple grind, and I used a thinner gasket .040 so I didn't need to change rod size. It is just math.

The LS7 lifters allow a wider range in preload.

I highly recommend Oil pump, Timing chain, and an upgraded aftermarket balancer.


2. I depends on how many times you want to remove and replace the MAF. I don't see any gain in using it at this point in the build.

3. Anything that affects flow will benefit from a tune. The cam is the most critical in terms of being tuned. After the cam you can tell the tuner what future mods you will be adding. I used ECS for a mail order tune and Highly recommend them. They are $150 and awesome.


You know that you will need new head bolts as the stock ones can only be used once. They are called torque to yield bolts. The harmonic balancer bolt is the same way.

 

The reason I raised my compression ratio is for the HP and fuel economy. It raises torque across the entire rpm range. I used a 160 degree thermostat and the ECS tune makes the fans com on sooner. I live in the south so it is not an issue. The cooler temps help reduce detonation. You will want to run 93auctane fuel or at least 91. Only use 87-89 in emergency's with higher compression.

Cams with longer duration loose a bit of dynamic compression and tend to like higher compression ratios. I recommend against raising compression this much if you are ever going to add boost or live in a hot dry desert.

 

If you're gonna cam it, a LS6 cam is too small, especially if you going to have 3.42s and a stall. Something around 228-232@113 will drive stock, give you a small lope, and about +20HP over a LS6.

 

Agreed to the above. If going through all the hassle of a cam swap, putting a ls6 in there will net you some gains but the time and cost to put such a small cam in vs waiting and putting a little bigger cam in would make it worth while. And if your pulling the heads to change the lifters and treys (which at 80k miles I wouldn't do) that just adds the cost to put your stock heads back on (given you don't get new heads). Just IMO and what I did was all the external bolt ons to help the engine breathe better and a good tune will surprise you how much the car wakes up. Then if it's still not enough then look into doing the heads and cam and even an intake manifold swap. That's just me though because I prefer to buy good parts and not have it break my bank all at once.

Also like mentioned above everything everyone said really depends on if your doing the work yourself or paying a shop on the cost vs reward factor

 

I would do it all at once, you "can" install the Vararam now but it causes check engine lights for some people on the stock tune. The 85MM maf will need a tune as will all the other stuff.

If your lifters in your car now are low mileage, use them. Even if they have 50,000-60,000 miles and pass inspection...use them. Thousands of high mile cam swaps have been done on stock high mile lifters with no issue.

I have seen cars with crate GM LS6 replacement engines, they are basically the engine I told you to build. They have LS1 block with 243 heads, LS6 cam and intake. They use the same 7.400 length pushrod pretty much all LS cars do. But I would check length regardless, it's easy to do.

What I described to you is a very cheap way to get 100hp.

243 heads-$400 all day long

LS6 Cam-$100 all day long

85MM MAF-No idea, but can be bought out of junk yards on LS equipped 5.3 and 6.0 liter trucks.

GM Performance sells this kit that should work for most of your gaskets Part #12499217

If you decide to change the oil pump, put a Melling stock replacement pump part # M295. You don't need a high pressure this or high volume that.

Leave the 190 degree thermostat in the car, it will be fine. It will improve engine life and gas mileage. Your heater works better also.

For a timing chain the LS2 chain only will work fine.

The recipe I described above makes about 440-450hp at the crank and drives like stock.

 

^I agree with just about everything FASTFATBOY says. I have done this build and like it. The reason I like it is for it's street manners. Mine is a street cruiser that may rarely if ever be raced. Just a fun car. If I was racing things would be different.

Our opinions vary slightly. I'm using the 160 deg stat but I live in Florida where heat is an issue and cold weather isn't. I also opted for higher compression.