stevieturbo

You'd have to ask the supporters of the FAST in this thread... can they actually show any proof, that it will offer any benefits ?
Because any I have read over the years, says it doesnt. Some even lost power on their FI setups.

hell, people are even making 1000+ on a stock LS6, Stock TB too. If your IC plumbing is 3", whats the point in having a TB much larger than say 85mm ?? ( to account for the area the blade takes up )
I really dont see the point in 3" plumbing, with say a 4" TB. The plumbing/bends will ultimately be the restriction at WOT, not the TB itself.

As for the carb intake debate. In my own experience, and I posted it before, my datalogs showed a very very slight, but repeatable increase in boost, when I switched to the Carb/Elbow/85mm TB
Same engine, same pulleys etc etc

geeteego

iTrader: (1)

I certainly didn't swap over to a carb-style solely for the marginal, if at all, increase in power. I wanted an intake that would stay down when screwed down. No warping, lifting, or distorting under high pressure. It's like a big, warm, aluminum security blanket for me.

SUPERBOOST

iTrader: (11)

I don't think this discussion can be over or end until someone actually compares the different intakes on a level playing field.Most input so far is opinon and theory,some very good ones and a few facts thrown in too. But this can't put it to rest,only a fair comparison can do this.I know there probably is not enough difference between them to warrant all this discussion or trouble but isn't that what it's all about,to find the best parts for a given combination that makes the most power?I think its a very interesting discussion no matter what the results are.

427

iTrader: (3)

Some interesting points in this thread, but from testing I have done different engines like certain intakes. A 34X engine under 7000 rpm with a street type power adder has not seen gain with a FAST in any testing we have tried. I have also never seen a pressure drop across a stock throttlebody with a street type forced induction engine. Now if you do a race type engine that spins 9000 rpm and makes 1400+ hp, the air needed will dictate the higher flowing intake.
Now on na engines, the FAST has always shown some power increase when we bolt it on. The most gains come on the larger cube engines running in the upper rpm bands, where you are moving large amounts of air.


Kurt

kp

iTrader: (34)

Thats all engines are, big air pumps, but under double atmospheric pressure subtle differences just get lost. it also depends on what you consider a significant difference to warrant a change. I never said that on an engine dyno maybe the FAST could have picked up 10hp over the LS6. But 10hp is most likely not going to show up as much if anything on a dragstrip with a 800rwhp car.

So in reality even if it picked up only 5hp the FAST 90/90 is in fact a 'better' intake. So that should make everyone happy.

As far as the VJ is concerned the main reason people use it supposedly better distribution since the runners are equal. Well the runners arent exactly equal, kind of hard to do with a single carb intake. I ahve one but never tried it, I dont think anyone one else has ever directly A-B'd one against a FAST or LS6 but there certainly fast cars out there using one, as well as fast cars with LS6 and FAST intakes as well..

Bottom line is its your money, if you truly think any intake is better for your application just buy it and dont look back and enjoy your purchase. Sometimes you just cant have your internet free advise to building a 1000hp cake and eat it too

stevieturbo

Sounds like a stock LS6 intake would be ideal then

FieroZ34

iTrader: (1)

Optimum intake manifolds for a forced induction application are simple. They are a box that bolts to the heads, with a throttle body. Runner length is as little as possible, even nothing, and plenum volume is as small as possible without creating a pressure difference before and after.

However the best intake manifolds for a N/A car aren't so simple. They require precise dimensions of runners and plenum volumes, trumpeting intake tracts, velocity stacks into the plenum, and much more.

Why such a huge difference on two very similar things (Air pumps)? Because on a N/A motor, the intake manifold's design can aid in RPM/acoustic tuning. This essentially times the pressure waves created by the valves so that they reflect back into the cylinder when the valve is opening, thus maximizing your actual intake volume. This is why short runner intakes help high RPM engines, and visa versa.

Well once we go forced induction, these pressure waves don't matter, and are no longer present. So the people that tune for them are only doing one thing--reducing flow. All a FI engine wants is FLOW. The more your intake flows, the more power you will make, the less boost you can run to make the same amount of power. Acoustically tuned intakes do not flow as good as they can, because of their design.

So why do people still use plenum style tuned intakes on FI cars? Why not make a box with a throttle body? Because boosted engines aren't under pressure all of the time. Turbos have to spool, and superchargers need enough air to overcome the engine's flow. So for the turbo, an acoustically tuned intake will help it spool faster, a lot faster in fact. A LS6 intake is going to drive and spool MUCH better than just a box. But once boost does come on, they are a flow restriction, thus you get a pressure loss across them, and need more boost to get the same amount of air into the cylinder.

My preference? I like my turbo cars to respond very well, and have great drivability and spool. In my kits, I spend an amazing amount of time on things the LS1 kits don't even consider. My charge piping length/size, properly sized turbochargers, intercooler location and size, and my hotside. Not saying these LS1 kits are bad, it's kind of had to make a slow LS1 with 10psi (Well, STS finds a way...). Point being, they are starting with a magnificent platform. And an LS1 naturally spools turbos very quickly, call it that American V8 torque. So they are going to spool any system pretty decently. My engine is not so magnificent, and getting that spool takes some work. The kits I build use stock intake manifolds. I want the spool/drivability they offer. To overcome this once boost comes on, I need to run more boost. But my components are such that running more boost does not hurt anything. I have a turbo good for 3 times the boost/flow levels, an intercooler good for double the power I've got, and every other part of the kit is over engineered. So I spend a lot of money to get what a LS1 does naturally. Good spool, and great numbers once they are spooled.

stevieturbo

So can you explain why I seen MORE boost in the intake, with direct back to back testing with my supercharged setup.

My Edlebrock, Elbow and 85MM TB consistently showed more boost, over the stock LS6 Intake and TB.

You are making a lot of claims in your post. I'll only pick on the one I have direct experience with myself, even if I dont necessarily agree with other bits.

Patrick G

iTrader: (14)

I have not been impressed with the Victor Jr. manifold in the NA world. The runners are too short for good power under the curve and the cross sectional area is too small to make big power gains over a properly ported FAST. It's basically a lose-lose proposition. In a forced induction application, the relatively small CS area keeps it from being head and shoulders better than the LS6 manifold under boost.

All this may change with Edelbrock's introduction of the LS1 Super Victor intake manifold. Now we have a short runner intake with a generous CS area. This should be a good thing for FI and a good thing for large displacement engines running high rpm NA. Can't wait to see some tests.

FieroZ34

iTrader: (1)

I'll assume you are measuring boost before the throttle body.

The only answer to this is that the Edelbrock intake/elbow/85mm don't flow as good as the stock LS6 TB/intake. I'm not familiar with the Edelbrock intakes, but I would expect them to flow more than the LS6 intake just by their design, which I assume is aiming for a larger cube/higher VE engines. I just spent a few minutes looking at a VJ intake again, as I'll be honest I haven't spent much time looking at them. Like Patrick says, the runners do appear to be awfully small. I wouldn't be surprised if the LS6's are quite a bit larger. Also remember the LS6 runners trumpet, at the plenum they are large and they gradually fade to match the head--This of course helps flow. It doesn't appear that the VJ runners do this, at least not noticeably like the internals of an LS6.

stevieturbo

So your post is full of assumptions rather than any fact.

TAQuickness

iTrader: (28)

How do you figure?

Patrick - As far as comparing the Fast90 to LS6, to definatively judge any advantage, you would need to have a fixed mass flow output from the turbo. This becomes a bit of a challange because of the nature of a wastegate. The wastegate regulates boost, not compressor mass flow output.

Assuming the Fast would be the better flowing manifold, if you were to keep 10 psi of boost in each manifold, it's possible you wouldn't measure a gain, or more likely less of a gain, with the Fast due to a lesser charge density caused by higher turbo RPM required to maintain the same 10 psi of boost.

As KP stated earlier, when he swapped the LS6 for Fast90, he experienced no measurable gains. However, after swapping back to the LS6 manifold, a cam and head swap each showed gains while overall measured boost was lower.

When I read into that, the cam & heads presented more of a restriction than the manifold, hence no measurable gain from the manifold swap. Now with free-er flowing heads and cam, there may, or may not, be a measurable gain by swapping manifolds again.

It's all in the recipe.

FieroZ34

iTrader: (1)

The waves that are created by the intake valve closing don't do anything. They are created, but as they are created you have air pressure holding them against the valve. So they don't travel, and thus you can't tune an intake for them, thus runner length and diameter has no affect beyond flow once boost comes on. Whereas N/A, the wave is created, and when it is created there is a vacuum on that specific runner sourced from the plenum. Thus the wave of increased air volume travels up the runner.

I didn't think of this, though it is definitely a valid point.

TAQuickness

iTrader: (28)

That's pretty interesting. I'm still having a bit of trouble getting my mind around it though. For the sake of splitting hairs:

Assuming the motor build is an NA application, and then atmospheric pressure just doubled for no good reason, wouldn't the accoustic wave still exist?

If so, how would that be any different than running 1 bar of boost on the same motor?

stevieturbo

Which is why comparisons on supercharged motors are better.

And Ive yet to see any proof that the LS6 intake poses a restriction, unless perhaps you are making crazy power ( ie well in excess of 1000 )

stevieturbo

And lets not forget...

ALL engines are boosted. They have at least atmospheric pressure acting on them.

FieroZ34

iTrader: (1)

I would like to see the results of just a box plenum bolted to each head, with short velocity stacks maybe 1/2" into the plenum, and a 110mm throttle body would do on the dyno on a supercharged LSX. Would be interesting to see how bad the LS6 next to an optimum intake.

Pro Stock John

iTrader: (34)

Kurt, you guys have seen gains with the single plane intake for race motors spinning over 7000 right? How would you compare say an LS2, LS7 and a single plane for app's spinning 7000 vs. say 8000?

WAHUSKER

iTrader: (4)

One thing I haven't seen discussed in here (tho I've heard about it) is the back cyl(s) starving with the factory style manifold, be it LS6 or FAST, under high loads. And that is why people with boosted engines say good things about the Vic Jrs. Any truth to this?

As for what I've documented with a FAST 78, I gained 15hp NA, and it survived 2 yrs of racing between 12 & 15 psi, but I nver tried dynoing with & without after the S/C went on. I did install the burst panel & blew it once tuning when the engine backfired thru the intake....

427

iTrader: (3)

Never directly compared the single plane and a composite at high rpm, but it would be interesting to try. We use a single plane when the rpm/power start rising, and the street use goes away. If I was building a car for the road, the LS6 would probably get the job. The LS2 is a little weak down low, not sure why but I think the runners seal is suspect. The single plane has distribution issues, but it will move a ton of air and is priced right.
The LS7 intake is very nice for a factory piece, but I have never ran boost on one.
The choice still depends on use, rpm band, weight, ci, type of driving and cost. No one intake stands out as perfect for all that I have seen.

Kurt