cablebandit

iTrader: (37)

fast 90/90 slowed my pig down in the 60'....maybe different for lighter cars but it didnt pick up on top either though the ls2 DID!!

ddnspider

iTrader: (26)

but i thought youre maxing out the incons? if you had like a thumper setup wouldnt you then be able to take advantage of the 90/90 because you can flow more air?

cablebandit

iTrader: (37)

ls2 trapped 137....ls6 trapped 137.....Fast trapped 134-135...ls2 was fastest mph in the 1/8

ddnspider

iTrader: (26)

wouldnt you make less boost with the FAST since it flows more thought?you'd need the psi that each of those runs were with.

Draco

This is wrong. Air is always pushed into the engine regardless of whether the engine is naturally aspirated or boosted. With an N/A engine, atmospheric pressure pushes air in at 1 bar of pressure. With an engine running 1 bar of boost, air is being pushed into the engine at 2 bar of pressure.

Reference:
http://courses.washington.edu/engr10...%20Engines.htm

More available upon request.

If a pipe flows a certain amount of air, and you double the pressure, then you roughly double the mass flow of air through the pipe. Of course temperature will be higher with the higher pressure, so this has an offsetting affect on the net mass flow. More mass flow allows more power (assuming this isn't offset by higher temps). Anyway the point is that if you gain say 10% massflow by improving the intake on a N/A engine, you will see additional improvement beyond that of the N/A setup in a forced induction setup.

69firebird

iTrader: (14)

Everyone on the board seems to think that head flow numbers are all important.
If you have a set of heads that flow 350cfm, and an intake that flows 270 (ala ls6) then your head flow is not as important.

the 90/90 can flow more but if you cant take full advantage of the flow whats the point, so conversly if you have an intake thatll flow 350cfm per runner, and heads that are stock what good will that do?

setups need to be matched get things that will compliment each other

I have a GMPP intake, and heads that flow 320cfm, so with any luck i am rather closly matched, now if I was running stock heads, i prolly loose a ton of power with the intake.(low end)

Slowhawk

iTrader: (12)

The only way to know is to do it.If your going 402+ the current LS6 head/Cam setup would bo no good for high HP.
Now I would expect a properly built 402+ with the motive you have to hit 900-1000hp.Of course an upgrade is in order for everything else in the car.

So far we've hit 700hp on a 346,AFR205 headed,220 Cam,D1 Vette on pump gas fairly easy.
New project currently being built 346ci,AFR225,224 Cam ,F1 Corvette I'm expecting 800-900rwhp on pump gas.We'll see

LSs1Power

iTrader: (5)

1 bar is what all N/A engines run at anyways. How is air then forced in the engine if its running at 1 bar since its the atmospheric pressue (I'm assuming a vacum created by the combustion?)? If there is air around which is anywhere in this world it will be around 1 bar right? A N/A engine can't pull more than 1 bar of air because thats the atmospheric pressure we live in right? That is why 1 Bar reads 0 in boost gauges because N/A engines can't pull more air than that. So when you have a device (SC or Turbo) that force more than 1 Bar of atmospheric pressure then i would call that Force Air in and anything that can't Force more than 1 Bar is Sucking air in not Forcing air in.

TTSSZ

iTrader: (8)

well Im still kinda new to the FI game, so here is the kinder-garden version
fwiw.

I think good heads and cam make a huge difference.
For instance;
If you run the stock short block at its limit, 600, 650rwhp, it is much better to run a good head/cam with it.
For one you can do it with a lot less boost. This makes it easer to tune and cuts down on your chances of detonation.
Don’t forget if your air flow is restricted its also building a lot more heat.
Heat kills power in FI motors and greatly increases the chance of detonation.
If I could do it over, I might have done the forged short block first before the h/c;
but just for piece of mind.

- I really don’t want to blow my mill.-

But I’m from the old school where a grate set of heads and beefy cam are everything,
and I think even though I dropped the compression 1 point w/ 6.0 heads, I have not noticed a difference on the low end when cruzing.
Also grate flow will get you up to full boost on turbo cars faster.
I still have stock intake and tb, have stage 2 heads and a mild cam made for boost.
At 8.5# of boost and a good tune, I’m really not pushing the stock short block to hard, and 572 at the wheels is good for a low boost daily driver.

Well well see…

cant afford a forged setup yet so well see If i can make another 11,000mi

Wet 1

iTrader: (4)

There's some good discussion in here, please keep it coming...

lock down

it looks like the heads do help but for the money you might want to forge the engine n run a higher boost.

FastKat

iTrader: (10)

$$$$$$$$$$$$$$

Dollar for dollar you need to decide where your money is best spent. If you have the extra $$$ money spend it how you want. Sure, better heads and an intake/throttle body are going to give you more power.... but it's gonna cost you a lot of money. Your cash will prob be better spent elsewhere FIRST for ex: a forged low comp shortblock, a cam, springs and pushrods, ARM studs, better turbo and intercooler, etc.

If you're breakin the bank, go for the heads, intake and tb!

Draco

Atmospheric pressure at different points on this planet depends on several things - altitude especially. Air pressure is lower at the top of Mt Everest then it is at sea level. Within a 4-stroke engine, Atmospheric pressure pushes air into the low pressure zone created as the piston travels down the cylinder during the intake stroke. A supercharger merely adds on to the existing atmospheric pressure (effectively simulating a lower altitude, or living on a planet with higher atmospheric pressure). Unfortunately a supercharger also adds heat, which partially offsets the increase in pressure.

Think about this... if you could get high enough to drop the atmospheric pressure to 1/2 bar (about 7PSI) and you ran 5 PSI of "boost", your net manifold pressure would be below atmoshperic pressure at sea level.... so whats the deal now is the engine still sucking the air in?

Pro Stock John

iTrader: (34)

I'm making 680-754rwhp thru some very average ported 6.0 heads. Would killer ported AFR 225's help? I bet they would not hurt. Might make the same power with less boost too. I have no idea.

I bet the sheetmetal intake and the 90mm TB would help but only above 5500 rpms or something.

LSs1Power

iTrader: (5)

We know that SC or Turbo adds heat, but this is not the point here.
Can any N/A engine "AT SEA LEVEL" take more than 1 bar of air in the engine? Answer is "NO"
Then SC or Turbo forces more than 1 Bar of air in the engine. Do u get it now?

Draco

Sorry man... I hate to correct you twice in one thread but you are also wrong about N/A engines being limited to 1 bar at sea level (do a google search for "interial supercharging"). N/A engines are capable of exceeding 100% VE (and thus more then 1 bar within the cylinder if outside pressure is 1 bar or higher) . You didnt reiterate your previous statement about engines sucking air so I will assume that you allowed that information to soak in.

And no, just because a supercharger is installed and is adding to atmospheric pressure, doesnt necessarily mean there is more then 1 bar of pressure in the manifold. I explained why in the last thread and will not do so again.

I gave you a reference from an academic source earlier but here is another:

http://online.physics.uiuc.edu/cours...5.ppt#287,13,1. Induction Stroke

And if you don't care what engineering or physics professors have to say, here is Chevy high performance on the topic:

http://www.chevyhiperformance.com/techarticles/49378/
http://www.chevyhiperformance.com/te...98/index1.html

Enjoy your weekend!

LSs1Power

iTrader: (5)

As i said before N/A engines suck air. In the article u listed it said "The pressure differential is created by pistons generating a vacuum in the cylinders."
Im no engineer, but when u have a vacuum created it will SUCK in. I said it before somewhere that there will be a vacuum created in the engine when the combustion happen which will result in sucking air in for the next cycle.
I would like to see engines running at more than 100% VE. I bet all N/A engines do huh. Just say u don't like Boosted application and u rather have your 150% VE N/A engine that makes more than 1 bar lol.
One more thing.....We are going off topic big time here.

Richiec77

iTrader: (3)

If you have a Low pressure Front vs. a Higher pressure front, The Higher pressure will Move into the opposing Weaker area. Thus it MOVES itself in. It depends on how you want to look at it. Potato/Toamato.

I look at as being moved in. Pressure Differential is what it is about. A Vacumm is only a Vacum @ a specific A/D value. 12.7ps in 14.7 PSI attmosphere is considered a vacum. In 10 PSI Atmospher it would be Boost!??

Yeah Off topic.

Lasershop

iTrader: (2)

Wonder how an LS1 would perform in a submarine!!! That was a joke. Dude, if you have the money... get the heads. If you dont, do them yourself.

jRaskell

iTrader: (1)

An SC, running at a certain speed is going to flow a certain amount of air. The level of boost generated by the flow of this air is determined by how restricted the motor that SC is strapped to. When you remove those restrictions, the boost drops, but the SC is still flowing the same amount of air. The mass of air getting pumped into the cylinders is relatively unchanged. It just requires less push(boost) on a freer flowing motor. You may get some nominal increase in power due to better efficiencies, but that's it.

You're absolutely right, boost != power. But that's why you can end up with the same hp #s on one engine running 5psi boost and then the same engine with free flowing mods (but no changes to the SC) only running 3psi. It's all about air flow, and until you do something to the SC to flow more air, the power you make is going to be limited to how much that SC is flowing.