Wet 1

iTrader: (4)

I know to really get the most out of a hot NA engine you need a good set heads that really flow, but with FI do you get the same gains as you would with NA engines? Say you gain 60 hp by bolting on a great set of monster heads on a NA engine, what would be gained on the same engine with FI??? Would you gain say 90 hp or do you not gain as much since the air charge is being forced in (meaning flow numbers aren't as critical with FI)?

What about the TB and intake? Is there much of a gain going with the 90mm/FAST with FI? Does it make any sense at all spending $3k+ on awesome heads and using a stock LS6 intake/TB, or is it a MUST to upgrade these as well if you're going with big heads?

Please give any real-world experience and feedback you might have... numbers would be great!

Got Me SOM

iTrader: (2)

in forced induction app's heads are not as critical. A set of valvesprings and a good cam are really all that's needed. If you want to make as much power as possible sure go ahead and get the heads done.

TB and intake are not needed. Going to a 90 slows down the velocity of the air.

Don't be so concerned with dyno numbers, see what it does at the racetrack.

You seem like newbie (not necessarily a bad thing) use the search button and look at the stickies on the top of this forum and just read, read , read. Lots of good information here.

ls1290

iTrader: (20)

I disagree. Well flowing heads, throttle body, intake, and matched cam are very important. The easier the air flows into the cylinders the more power will be created.

Trying to overcome poor flowing components by increasing the boost is not the answer. Built up air in the intake( aka boost ) is wasted because it is not getting into the cylinders.

I would rather have a well flowing system making only 2 psi of boost rather than one with the same blower setup making 15 psi of boost.

Keith

ddnspider

iTrader: (26)

thats also in an ideal setup which obviously doesnt happen....a stock setup you may have 12#'s whereas some head work intake etc you'd have 10#s.someone just had a thread that theyre only seeing 5#s with their 8#setup...but they have exhaust and intake mods to help the flow.if youre on a stock motor anyways youre limited hp wise at it is.If you have a forged motor with all sorts of upgrades then it already makes sense to get hood heads and intake.

Zombie

iTrader: (2)

The HP per dollar is not worth it when you can gain the same HP by simply turning a ****. It all comes down to your wallet.

FastKat

iTrader: (10)

A general rule is that (holding other things constant, except fuel) the more air you can flow through your engine, the more HP you will have. Better heads, intake manifold and throttle body will help you flow more air, even if it is being forced through the engine by a turbo or supercharger... but what I think you're really asking is if this is the right move for your setup??

That depends... what are your goals??

LSs1Power

iTrader: (5)

The HP/$ ratio for doing heads/90mm TB/90mm Manifold is not worth it unless you maxed out the setup and u wanted the last 20-30HP's. If a set of good heads/TB/Manifold gave a N/A setup 60HP i think it will only show 20-30HP on a FI setup. Air is being forced in the engine when running a FI setup while air is being sucked into the engine with a N/A setup so it really needs better flowing Heads/TB/Manifold to get more air in.

Same thing goes with the exhaust setup even though the exhaust setup will give larger gains to a FI setup than Heads/TB/Manifold.... Keep in mind I'm running 1 3/4 headers/3" Y-pipe/Hooker Catback. I gained 10rwhp 7rwtq with a cutout on my car N/A and only 5rwhp 2rwtq with the cutout and boost.b Gains would have been alot more if i were running stock headers with stock exhaust, but what im trying to say is that its not worth it going with a 1 7/8 4" exhaust over the current setup.

So if you have a good base (LS1 Heads/Stock TB/LS6 Manifold) to start with keep it and use it until you max all the possible cheaper mods and then dig into the uptapped more expensive less HP/$ mods.

Good luck

Pro Stock John

iTrader: (34)

My research tells me that if I could find a set of heads that flow better than my current ones that I would make some more power.

My research also says that my current LS6 intake/ported OEM TB setup works really well... But that a swap to a 90 mm TB and a different intake might benefit too.

I'm waiting on a custom sheetmetal intake that will fit a 90mm TB. I plan to just change those items sometime in the fall and dyno the changes.

Wet 1

iTrader: (4)

To answer some questions about MY engine... I ask the question because I'm going to build another engine over the winter to replace my stock 02 LS6. The new engine may very well have more ci (402 or possibly 427 ci). I already have a SC, so this basic system will be used. Before I build the short block I'd like to know what I'll be using for heads... (11* or 15* heads etc.). If heads make a major difference with FI, I'll spend the money and get the huge 2.100 valved 11* heads and intake (but I'd need to have the pistons built cut for them).

I realize the better the heads and intake flow the more power it will make and that you can always just add more boost to over come crap componnents... And yes, I've done plenty of reading and have been playing with FI engines for MANY years. I was just hoping a few people might have some solid #'s/info on this topic.

CHRISPY

Personally I would look at the cam before the heads if you have a street motor and stock cubes.

If you are on a budget a cam selection and exhaust will make the biggest difference within a "street" power range (500-600RWHP or so)

If you keep turning up the boost you will eventually reach a saturation point where you can turn up the boost but not make anymore power.

That is usually (but not always) the result of an intake restriction or moving outside the efficiency range of the blower/turbo.

A good blower cam and set of headers/exhaust can actually lower boost but give an additional 70-100RWHP easily over stock configuration.

LS6 intake has no sealing issues (like some of the FAST intakes) and will not heat up like a sheet metal intake. It'll also support TONS of power.

I would consider LS6 intake, blower cam kit, good exhaust and stock heads.

Cheers,
Chris

99SS-T

iTrader: (5)

I think heads and intake are a waste if you arent going for broke. I mean heads are 2k, or more for the heads you speak of, and the only manifold i would ever consider is one of the carberated manifolds with teh elbow bolted on top. Those make for even distribution of air where as a FAST or LSX intake will still give you the lean 7 and 8 cylinder. But they aint cheap. Once ya get the intake manifold the elbow and have it milled for injectors ya will have 800 or so dollars into it.
So as i see it for the price you spend on the heads ya could forge the bottom end of the engine, and have enough left over for the intake.
Obviously all up to you but i think 2k$ is out of control.
With a 402, or 427, you will be able to make a ton of poweriwith or without heads. Just do a minor port match job on them adn ya are set. GL man


John

jRaskell

iTrader: (1)

An FI setup can benefit just as much from other engine mods as a naturally aspirated setup can. If you're running a supercharger, engine mods will drop boost, thus requiring a pulley swap to get boost back up to it's previous level and get the true benefit. On turbos, you'll see the benefits right away (all assuming proper tuning)

A built engine running 5psi will make quite a bit more power than a stock setup running 5psi.

ls1290

iTrader: (20)

Wrong, wrong, wrong. The reason why one sees a drop in boost, psi in the intake, is that the air is going into the cylinder and not building up in the manifold. Built up pressure in the mainfold is waste, because the air is not going into the cylinders. You will be making more power at a lower boost level.

HORSE POWER != BOOST
HORSE POWER = AIR FLOW

Keith

FastKat

iTrader: (10)

True, because the built engine is flowing more air. But a lot of times you have to make sacrafices... if you have a huge cam and huge valves, you're probably going to sacrafice your low end output, pushing the torque curve (and the horsepower) farther up the RMP range.... good for the 1/4 mile... not so good for daily driving.

It all depends on what your goals are!!

ddnspider

iTrader: (26)

ls11290 i believe thats what russell was trying to say....obviously if you have less restriction youre going to have less boost but make the same hp you would at a higer boost level without those mods...for example....say im making 8#s in a stock motor....now i add an ls6 intake,headers,exhaust and a throttle body....now im only making 5#'s of boost...but still making the same hp.If i get a smaller pully to bring boost back up to 8#'s NOW im making substantially more at 8#'s than i was b4....thats what he was trying to say,which is basically what you said.

ls1290

iTrader: (20)

That is impossible. If you are making 3 pounds less boost, where is that air going? It has to be going into the cylinders. And if it is going into the cylinders, you have to be making more power. Air does not magically disappear

Keith

mahhddgtp

Quick question. This applies to Turbos also, correct? Not just superchargers.

Post noted. I agree with your logic.

ddnspider

iTrader: (26)

OMG!it was an EXAMPLE!theres was a thread with the exact same outcome with a s/c'd camaro.i was pointing out how you end up with less boost....you need to relax and stop jumping all over people.How does Donna Summers name apprear in the Phone book???

Got Me SOM

iTrader: (2)

i dunno but lets order her a pizza.

ddnspider

iTrader: (26)

AH!NO! have you never seen Saturday Night Live about that?NVMD!someone whose seen it knows what im talking about.