I'm sure many of your fellow California vette owners will chime in with recommendations, but I think the largest cam you can go with and still pass emissions is something like a 224"/224" .588"/.588" 114 LSA. It's a relatively small cam, but will still give you significant gains in horsepower and torque. A ported set of LS6 heads will provide sufficient flow to support a cam of this size.

 

Better heads will net some gain but whats the use if the stock cam profile can only support so much air. The cam and head must match up and compliment each other to get a serious gain for the coin you will be dropping in

 

243 heads will be a good upgrade over the 241's especially if you are doing a cam. And the 243's can be improved by polishing and or porting and need to be shaved to keep the DCR up when going with a bigger cam too. If you really want that little extra punch and can justify the exorbitant price the aftermarket heads are even better. Don't forget the little things like PP the throttle body and matching the intake manifold to the heads too. It's easy to get 430-450rwhp with a streetable cam and heads upgrade, that's a huge increase over a stock LS1 C5.

 

Sounds like everyone has given sound advice. It appears you are looking for throttle response since you don't track or course. If that is the case, i would go with gears and call it a day. If you opt for H/C, you can probably find a good deal on a set of stock 243's and a stock LS6 cam from someone looking to upgrade. Another good cam choice for CA is the stealth if you go that route.

 

They cant smog check gears either!!!!

 

Contact Tony Mamo at AFR (PM him here on the forum). The AFR's, milled for more compression, and the smaller AFR cam will pass CA emissions. The fact that the AFR's have a CARB number and have since day one is another factor in their favor. The smaller cam doesn't give much up to their larger 224/228 cam (although some do not consider that large). Correctly set up, this will pull from the bottom up with no problem. Tony is not too far north from you and can probably recommend someone that he trusts to do the work as well.

 

If you want power that's CARB certified, just get a blower. The procharger, vortechs and maggies are CARB certified. I'm pretty sure the Kenny Belle is too.

If you go with the procharger or the vortech, you don't need to pull apart your motor and you can make GOOD power without making your motor unreliable by pulling it apart.

That 224/228 will pass smog sniffers. The 243 heads are pointless without a cam to match. Personally, I'd just do a blower and call it a day.

 

Thanks for all of the input guys. I appreciate the replies since I'm sure the subject of H/C have been covered time and time again. Again thanks for the feedback.

Basically this idea started because I want LS6 performance from an LS1. This means upgraded heads. The simplest solution is to swap a set of 243 heads on. Since you're making the effort of changing the heads why not get a set of P&P 243 heads. With what we spend on bolt-on mods with these cars, the difference is a drop in the bucket for corvette enthusiasts.

When I implied that money was not a limiting factor. What I meant was I would be willing to spend the extra amount on aftermarket heads. No the ski is not the limit. This is what kills the idea of a supercharger. The cost is just too much (I've been told you're looking at $8K easily) right off the bat. I have also seen a post by Tony saying that boost applications feel sluggish when not under boost. Then he goes on to describe how H/C application have more torque at low rpms. This is what I am interested in.

AFR heads have a CARB number. This makes them very attractive. However, I have since learned that other well known manufacturers also have a CARB EO#. BTW, just to pass on the information Tony Mamo said that the tallest cam that would guarantee to pass smog would be 220/224 w/ 114 LSA. He went on to say that 224/228 could pass but you would have to have your A-game (fully heated cats) to assuredly pass.

 

So gears are part of the equation, realistically the bigger part?

Airflow & velocity in the lower lift area's regarding the cylinder heads is equal & more important than WOT.

 

Actually, not all supercharger setups are $8K. Actually, the A&A Corvette kit is $5,200 right now. With install, you're looking at about $6,000 to $6,500 total. It's a pretty easy install for the most part and a lot of shops do them all the time.

As for being sluggish, I've never really felt boost lag from a supercharger. Only turbos in my experience. Superchargers were designed for torque. They make power almost instantly because they're belt or gear driven off the motor. Turbos will lag a bit because they spool from exhaust gases. So I'm not sure what info you were given about the boost lag, but superchargers give you a very linear power band.

Heads and cam is nice to have, but harder to pass smog with. But it's all still personal preference. The good thing about superchargers is that many have a boost-bypass so that if you're not on the gas, it's not drinking your gas. If you go with a H/C package, it's a different story.

Of course, if you're going to go for the "always on" power, go with a torquer 2 cam and the 243 heads and that would be good enough to put a nice ear-to-ear grin on your face.

 

The issue then becomes do you add headers? Fool around with the O2 sensors??? All the other headaches of Cali emissions??? Supercharger is the easy and leaves ther car essentially stock.

 

While a supercharger system like A&A corvettes is attractive for the massive boost in power. But with such a great pro there is always a con. Largely the cliche I've heard, "after you get finished installing a supercharger, start saving for the engine rebuild after it blows". I would have to say once you go supercharger you can never go back. I would be reluctant to buy a car with an aftermarket supercharger. I know the engines days are numbers.

If we are talking about A&A corvettes system, then I assume we are talking about a centrifical supercharger? If so the engine won't see boost until the rpm are increased. You won't have full boost until peak rpms. At moderate sppeds you won't see the big power gain and the superchager will rob power from the engine (takes power to turn, just like the alternator). Supercharged engines also like lower compression, another hit to low rpm power. And I'll have to take the heads off to install thicker gaskets. Migiht as well put aftermarket heads then?

Now the above could all be solved with a magni supercharger with torque at low rpms. But then there is a new hood, new paint, yada, yada, yada.

Then there is the cost. While a base system is just over $5K other mods will be required. With boost comes heat and stress on the engine. Upgraded cooling system and lubrication parts. Adjustments to the fuel delivery system, tune. Then of course there will be the need for more traction, new rims, bigger brakes, don't forget the meth system to stabilize the intake temp. The people I have talked to generally have said it's about $8K by the time it's all over

 

HP is always sexy, Safety equipment not so.

Safety up grades are the upgrades you hope you NEVER have to use, until you do. Then your glad you did spend the money to put in the seats, harness system, BBKs and brake pads, Better tires, and in some cases fire suppresion.

 

^^Plenty of stock vettes running modest boost with impressive results. The thing is not to get too greedy.

The SC boost does take some rpm to reach full boost, but the power starts building around 2500 rpm. There are plenty of dyno charts out there comapring stock to boosted power curves. Lost fuel economy is small.

What hasn't been mentioned is the need to improve driveline to handle increased power. That will cost some $$$.

 

Running 500RWHP isn't that bad. The LSx motors can handle that just fine. Just because you have a blower doesn't mean you have to run the smallest pulley they've got. Getting greedy was the right way to put it. You can make 500RWHP with a stock motor on a large pulley and the motor will be OK.

As for boost, S/Cs make boost lower in the RPMs whether it's a root-style or centrifugal. The root-style DOES make more power at lower RPM, but it's not nearly as efficient as a centrifugal. The centrifugal will make plenty of power in the low end as well, though. Remember, they're BOTH belt driven. Even the root style isn't going to hit max boost until max RPM is reached. The centrifugal S/Cs hardly take any hit to the motor when not in boost. Equivalent to an alternator, the by-pass on the S/Cs spin almost completely free.

You're afraid you'll blow up the motor, which I can understand. But no matter how you make power, HP kills motors. LSx motors handle blowers just fine, though. There's a million guys on here that have FI LS1s and they're not blowing them up. It has a lot to do with the tune as well. A safe tune may not make a million HP but it will also keep your engine running.

Food for thought.

 

One minor correction. Roots style superchargers make max boost as soon as they are turning. Increased RPM's increase volume, not boost. Centrifugal superchargers increase boost with RPM, like a fan. This is why a Maggie has a bypass valve and Vortech and Procharger don't. They have a blow-off valve to release excess pressure when decelerating.

 

From what I understand (and I'll find the info site) one of the centrifugal S/C has a bypass so that it's not robbing the motor of power under no load.

 

Putting a bypass valve on a centrifugal supercharger would be like putting a set of wheelie bars on my car ........ there's just no need. Centrifugal superchargers don't make enough boost in the lower RPM range (below say 3000 RPM) to create enough drag on the engine to worry about. This is one of the reasons centrifugals are considered to be more efficient than roots type superchargers.

The purpose of the bypass valve on the Maggie is to relieve excess boost at lower RPM to make it more drivable. Can you imagine trying to take off from every stoplight at max boost?

 

X2. The AFR heads are most excellent but, you most certainly need a cam that takes advantage of the increased flow characteristics they offer. Your budget goes up considerably to R/R the cam as you will need to replace the cam chain/sprockets, underdrive pulley etc and pay for the labor. Since your 2004 already has an LS6 intake, with heads/cam the pinch point remaining will be your exhaust manifolds which further pushes up the cost and concerns for passing emissions tests.

Perhaps you should start modestly and have a tune done on your existing stock setup. A tune will help in the throttle response and you should see a modest but detectable increase in torque/HP. Your described current needs may best be met with a tune and you can continue to investigate future engine modifications which will no doubt be in your future. Good luck...

A1

 

Well, I'd still say either a CARB certified blower or if you're getting the heads/cam, go with the LS6 STG 2.5 heads with the 224R cam from TSP. It's about $1800 for the whole package with chromemolly pushrods and strong springs good for .650 lift (even though you're not going to go with that much lift). That valvetrain will last forever and the cam will give you a nice big grin.