So I recently got a C5 and I love it. Want to add some power. Various online post says go with new heads and cam. But my local Corvette mechanic is saying dont touch the internals, that heads, an LS6 manifold and a cold air intake will be more than sufficient. Thoughts from the forum? Do I need a new mechanic?
Thanks to all.

 

Ur wallet will dictate ur hr power. Don't mess about. The best bang for the buck is heads cam headers and finally tune. .eazy 60hp. Don't worry about 15hr from intake for a bunch more money.

 

A few questions that need answering to advise well.

1. What year is the car?
2. Automatic or Manual Transmission?
3. Do you need to pass smog inspection?
4. How is the car used? Daily Driver, weekend cruiser, canyon runner, auto-x, HPDE, drag racing?
5. What's your budget?

 

My car is a 1999 manual transmission car. I live in NY and will have to pass smog inspection.
It is a weekend cruiser.
My budget is 6K, but I am flexible.
Thanks.

 

For $6kish put a supercharger on it and call it a day.

 

^ that's the real answer

I don't know how strict NY is, but you could do all OEM parts, mixing and matching to get a ton more power

Ported/Blended Gen 3 4.8/5.3 heads will bump compression
Gen 4 4.8/5.3 heads (799) are allegedly the same flow as the 243s LS6s had, just not equipped with lightweight valves
LS6 intake manifold
LS2 throttle body
LS6 or LS9 cam (LS9 cam needs supporting mods, like timing cover, cam sensor relocation and a 4x timing gear)
LS7 exhaust manifolds
LS6 or LS7 air intake and bridge

I'd say that with tuning- the above will net 100hp gain over what you have now. It'll probably
also cost a lot. Blower is the real answer

other things that pass inspection but bump hp- electric power steering conversion, electric water pump, larger alt pulley, underdrive crank pulley

All the above (sans mention of blower) will blow (giggity) your budget

find a used centrifugal blower and call it day. Stock drivability, with more power

 

I take it you will not be doing your own work?

 

I totally agree. A NA motor does have some pluses, but add a cam, heads, tune, etc, will not have the reliability of a FI motor, and probably wont have near the power. There's a reason the OEMs have gone FI on their highest hp performance cars.....

 

Mine has a Supercharger, ported 243 heads, larger injectors, cam and tuned (obviously). I just passed Mary-Land emissions. Maryland looks at 8 items but looking at NY's page, they only look for 7 items:
New York State Vehicle Safety/Emissions Inspection Program | NY DMV

• Catalytic converter (CAT)
• Exhaust gas recirculation valve (EGR)
• Positive crankcase ventilation system (PCV)
• Air injection system (AIS)
• Evaporative emissions control (EVAP)
• Fuel inlet restrictor (FIR)
• Thermostatic air cleaner (TAC)

Surprised O2's are not on the list of things they look at! That was the one that took the longest for mine to set after I put in a new battery prior to the emission testing. Dang, you guys have to do that yearly! Here in MD, our communism only requires it every 2 years. My point is, you can mod and still be emissions compliant, just make sure your tuner knows how you plan to use the car.

 

I'm 68. I replaced the exhaust system myself and was sore for a week. No, I will not be doing the work myself.

 

Very good mechanic. Don't mess with it. Don't open it. Leave it alone. Put a supercharger on it and pray you can get it tuned properly for minimum timing and safety with varying fuel and load quality. Correct plug heat range NGK iridium. Sterile plugs - dont touch them with skin contact. Oil temp monitoring/cooling. Intake air temp < 112*F on gasoline fuels. Intercooler with forced induction when using gasoline. etc

The less you do to an engine the more reliable it will stay from a factory.
The next level of reliability is learning to measure crankcase pressure which is an essential toolkit of forced induction tuning.

In other words, to mimic and improve on the factory PCV system during forced induction application additionals.

Examples in my build thread sig

 

Everyone here is on about the same page. Add a blower kit and a fuel pump, maybe valve springs, have it tuned by Trevor Timpone right out by you at Grizzly Tuning (one of the best in the country for LS and Corvettes).

The cool thing about blowers on stock engines? It drives like absolute normal around town and on the highway right? But once you put the spurs to it and it gets over 3k it slaps you in the butt nicely. Like having your cake and eating it too. An A&A V3Ti kit will fit your every need. ECS is based out of NJ down the way and they run comparable quality all the way using Novi blowers. You can't go wrong. Or you could get an ECS kit, pay them to install it, AND have Doug tune it for you. He is of course another pro with Corvettes and LSs.

 

Congrats on the C5! Your mechanic’s advice isn’t wrong — heads, LS6 intake, and CAI will give a nice bump in power. But if you want real gains, a cam with the heads is where it’s at. It just depends on how aggressive you want to go. You don’t need a new mechanic, just a clear goal for the build.

 

Having done the argument in the past, if you dive into heads/cam and do all the right "while I'm in there" upgrades, parts for parts, you end up in the same supercharger territory or higher. Add labor if not doing it yourself. And then add the trust factor or lack thereof of your mechanic.

Heads and a small cam are still a viable and great way to go. It is just a different driving experience to have in the end.

 

So, I am leaning towards the supercharger route. My car is stock and has 40K original miles. Can I seriously add a supercharger to an otherwise stock engine and not have it blow up on me? An engine rebuild is NOT in the budget. Thoughts? Experiences?

 

I may be in the minority but I'm not a fan of a S/C on a stock bottom end. A good friend of mine put an LSA unit on his low mile LS3 powered Camaro and had a catastrophic failure. https://www.camaro5.com/forums/showthread.php?t=613116
I say keep it simple. A set of quality headers, 3.90 gears (since you currently have 3.42s) and a good tune from a reputable shop or individual. .

 

Better have a good tuner, if not no, if you do you'll enjoy the car for many yrs. But again ur going to add minimum off 150hp with low 7ish lbs boost. So who says if it was you that blew the engine or tuner. But if you have the 7k to 8kish go for it. If you can find a used one u can save 1000's.
Just add the kit. The engine can easy hand 500hp to 550.

 

Oh man. Here come the boomer repeaters. Unless someone has had DIRECT experience, don't listen to their so called experiences through others. That often only spreads false information in the community.

LS1 / 2 / 6 / 7, L33 and all the others etc.... are now almost a 30 year proven product which has seen every level of development and abuse. These are STRONG engines. While I would not recommend 800rw (1000 crank) on a stock bottom end with boost for longevity..... it is ENTIRELY COMMON among swappers and racers to do exactly that and run a full season with hundreds of drag passes on same setting. Gap the rings and send it basically.

So a mere 600rw is well within the comfort envelope. Therefore the more common 500 to 550rw is even moreso. It is also that happy level where you are not going to be breaking the rest of the drivetrain or other parts at all. Caveat: this does not apply to anyone with a 4L60E.... those can be stock and eat themselves.

If one goes SC'd there are some addons to consider:

Fuel pump - for approximately $100 a Walbro 255 or 430 will power your ride and is an easy install. I don't subscribe to voltage boosters, but I do like them for the fact that a layman ends up with a relay powered straight off the alternator/battery which is a safe/wise thing since fuel keeps the engine alive.

Valve Springs - not required, but cheap insurance and a mild performance booster. The ancient valve springs are designs for the stock cam and power level. They can sometimes float slightly at high rpm under boost which does not hurt the car but does reduce power slightly. Small expense to keep the valves closing fully.

Rocker bushings - very not required, definitely a "while I'm in there" topic, but replacing the factory needle bearings on the rockers with solid bushings provides a level of safety since a needle bearing letting go shuts the engine down until you tear it down and remove every last one. A bushing.... might wear slightly over 100k but will not affect the engine in the same way if there is ever damage. This is purely a safety upgrade independent of any SC / cam etc.

Trans mount - even on stock power you might think you feel wheel hop. That is actually drivetrain hop. The transmission is suspended mid-drivetrain and can wobble. This can be amplified with more power on the car and the wobble can cause failures such as the case splitting. An upgraded transmission mount reduces this risk greatly.

Diff brace - similar to above. For $400 some say it helps prevent failure by keeping the diff and trans mated firmly. Others say it just keeps the pieces together if you nuke it. At 600rw the risk of this is very low unless you are slapping slicks on the car at the drag strip and doing superstar 4500rpm launches. The key being how hard the tires may bite which send shockwaves into the drivetrain. If your tires peel out you're fine because there is no load. If you straight hook like slicks on a prepped track, every bit of force goes into the drivetrain like loading up a spring. It can flex, it can also snap. Slicks have the benefit of wrapping the sidewall which helps safely load the drivetrain. I think it may be DRs which negate that and are the ones which do more damage if straight hooking. On the street? You will basically not have to worry about this. But most of us do the diff brace anyway.

Clutch / Flywheel - no need to go diving in to change this with the blower install, but when the factory stuff wears out is a great time to upgrade. I highly suggest a twin disk clutch setup. For 600 and below, the RST is lighter foot than factory and fully comfortable as a daily. Many say to go RXT since most people get a taste for power and then want more. I have owned both. Both are fine for daily. The RST is still a bit easier and so I suggest it for weekend cars unless they are doing the Mexico thing or track days. Flywheel..... I have been using lightweight flywheels for two decades. The boomer repeaters will say "you have to learn how to drive it," "you can't launch with it," and other complete nonsense which almost always comes from someone who has only ever driven stock or near stock drivetrains. I've driven them all. The Corvette being a sports car, the lightweight flywheel makes those aggressive backroad hills and country rips where you're shifting frequently and pushing the car extremely easy to rev match and shift on a dime. Even on a factory cam this is apparently, but on a turned up engine it is a phenomenal experience. It slips different from a stop and you learn it in 5 lights or less. It is that basic. To the many who say to stick to factory LS7/LUK clutches and flywheels..... I honestly judge them for putting "Truck" clutches in their sports cars. To those who complain I then also ask them if they'd complain about driving a Ferrari or not. I have happily used Fidanza lightweight flies almost exclusively. Their rebuild plate only costs $75 should you ever need to while you own the car. Further, Tick sells an adjustable master and grab yourself a remote bleeder and a Russell 641370 to mount the end to the bolt at the brake master to keep the line cleanly out of the way.

Good tires.

Good brake pads.

Good shifter with a TMODcustoms tub. And if you do the clutch ever, plan the 3+ day turnaround to grab the TMOD linkage mod. Yes. Both products are fully worth the price on a stick car.

A lot of peripherals there, but not a lot required. Trans mount. Fuel pump. Valve springs. Are the keys in my head. The rest is optional or when needed.

***** THE ONE KEY TO SUPERCHARGING *****
IT does not matter if you run 3psi, 10psi (about the max I'd choose on a stock bottom end), or 16psi.... if your tune is not done well you absolutely can nuke your engine.

WHO you go to for tuning is absolutely essential to the process. A clean tune is a safe tune. Much as I know, I am only wise enough to be dangerous in this category. And so going to a proven, known specialist in the LS / Corvette platform and boost is the one and only thing you need to worry about. Tell them you want the full send, all day, pump gas tune and you will have all the power you may want but able to be used where you don't aerate the block because you chose Jimothy the Enchanter who every local guy says is "the one." No. Come here and we will let you know. If this is the Long Island thread, then Trevor Timpone all day. Or if you buy ECS then go the extra fifty miles and have Doug Ring and his team install and tune it for you in NJ.

 

Its not exactly a truly fair comparison, but I have a 268k Tahoe that has had ~20k mi of centri boost put thru her. 5.3 with 218 cam, LS6 valve springs and heads that have never been removed

She used to tow, boosted. She goes offroad. She parties hard at almost 6000lb curb weight and 12psi/477rwhp thru the stock exhaust. Only problem Ive had was the fuel pump dying. She doesn't even leak oil

I would ABSOLUTELY boost a completely stock LS1 in a car 1/2 the weight with tires for fuses

I would do it today and never look back

 

A forced induction engine is more reliable than a factory engine if done correctly. If I installed the supercharger with my experience and tuned it myself it would be so.

But this is not true for random installations. Stuff gets done wrong. Dirty. Bad tuning. A stock engine is a 1-mistake engine. One mistake its done, get a new engine. There are so many mistakes you can make. I could make a list here of about fifty mistakes people make, including 'professionals' and shops with 50 years of experience. Sorry thats just how it is.

Modifying engines is always a risk unless you've done it yourself for decades and have the necessary education and experience to practically guarantee success with a historical reference of successful engines that achieved high mileage already. The supercharger can reduces the number of risks significantly(as opposed to say, bottom end and head/valvetrain mods) and makes a more specific set of risks to watch out for that are easier to manage with a factory engine that started out as a reliable engine in the first place. Keeping dirty mechanic hands out of the engine is part of that limiting ability a supercharger has which is highly beneficial to a novice.