Kano

iTrader: (3)

I would like to see more information on intake design.
runner length vs rpm max flow that sort of thing



and at what point the intake becomes a restriction.

Here is what Im facing
I have a LQ9 with WCCH heads and F-11 114 camshaft
all bolt ons TD exhaust 2.5" no cats
CR is 10:1
BTW this is with the long runner truck intake

heres my graph


You would think this cam would pull higher than it does
I think the reason its not is due to the intake design

Around 5000 my maf readings jump around like crazy from 42 to 48 lbs

I have a friend with the same setup as mine except cam that does exactly the same up top.
he will chime in also

Any info, thoughts, opinions on this would be appreciated

mattrem

iTrader: (7)

I have the almost same combonation, except the cam. I had a 216/220 Comp with 1.8 Harland Sharp rockers, on the dyno mine fell off at 5200 rpm. I had some valve float I think from the rockers. I have swapped cams again, 220/224 581/581 with the stock rockers, hope to go to the dyno this week with it.
I made 355ftlbs and 350 hp, it stopped pulling at around 5000 rpm.

We are the only 2 truck guys with heads and cams that are N/A. Could the manifold be holding us back? All the truck guys making big power are FI, I know the FI could be helping the truck manifold, but could it be hurting us?

Beast96Z

iTrader: (21)

The trucks are designed to make peak power and TQ early for towing and other things. Changing to a shorter runner will move that power band up and probablly sacrifice some of that mid range TQ. The higher you can rev, the more air that can be moved, equaling more HP. Changing to a LS-6 intake or a FAST will give you a power band that looks more like the cars.

Kano

iTrader: (3)

so this a runner length thing?
What exactly happens inside the intake that causes this?

Im not but theoretically,
What would happen if I went with a larger cam?
Lets say 238/240 114 +0

would top end gain
or is the powerband stuck at a certain RPM?

Kano

iTrader: (3)

How about plenum volume , runner volume, and runner length
differences between the LS6 truck and trailblazerSS intakes?

Beast96Z

iTrader: (21)

If you went with a bigger cam, your power band could gain in the upper rpm's some, but it is still going to be mostly low-end since the intake was designed for truck type duties. If you keep adding camshaft, you'll end up with a cam that makes power outside of your intakes powerband, and then you'll be left with unsettling results. I'm deffinatlly no expert on port volumes vs. legnth and other things, but I do no that longer runners build TQ, wearas shorter runners are better suited for high rpm HP. If you look at some LS6 intake dyno's, you'll see that most of them have a HP that is higher than tq. Wearas yours has a very fat TQ curve, that produces more TQ than HP. You'll have to comprimise somewhere, because you need a fair amount of low-end TQ to keep the heavy truck from being a slug off the line, but you also want to pull up top a bit more.

Sport Side

iTrader: (6)

Ignoring the intake design, it comes to this.

1. Truck Intake + 6000RPM shift point
vs.
2. LS6 Intake + 6500RPM shift point

A 'correctly' cammed 6.0L with supporting gears/stall will
net you the lowest ET.

Like Beast stated, the LS6 intake is going to allow more
RPM travel which will give you more HP.

It's going to take experimentation because it is hard to
say right now 'how much' low end will be lost when and if
you add a new intake.

So, lets recap... How much street-ability are you willing
to give up?
Well, this depends on how much you loose on the low side
from the intake swap. It's going to take testing.

Kano

iTrader: (3)

I understand all that
Im just trying to get a grasp on why

We got 2 applications here one with a 228/230 114 and the other with a 216/220 11?
My understanding is the f11 would pull higher than the 216/220
but we're within 6rwhp and both fall off around 5000.
So I think its best to call the intake... "done for after 5000"

Thanks for the responses beast
Its good to know someone else agrees with us and
this being an intake thing.

Kano

iTrader: (3)

Sending you a PM

oange ss

iTrader: (50)

airflow stallin in the runner at high rpm

mattrem

iTrader: (7)

My cam was on a 114lsa to clear this up. Now the next question, will the LS2 truck manifold, help or hurt in our situation? It looks also to have long runners like the truck manifold.

oange ss

iTrader: (50)

i didnt know there was an LS2 truck manifold

mattrem

iTrader: (7)

Yes its used on the TBSS and SSR, it has a 90mm TB. Scoggin Dickey is testing a harness to go from the 6pin to 8 pin TB. Its tall like the truck manifold, I think it has more volume. If it makes 395hp on that LS2 would it support the same on a LQ9?

Sport Side

iTrader: (6)

I don't think the LS2-Truck will be the answer. It's making
395HP at the motor. Kano and yourself are more than likely
already past this point.

I think it is the design of the intake leaving us RPM limited.
Swap the intakes, and cam/stall/gear occordingly and you
will go quicker down the 1320.

Sport Side

iTrader: (6)

Here are some examples.
Some look better than others but, the 6200-6400RPM peak that the LS6 intake usually shows does not appear in these graphs.

6.0L + 228/230-110ICL + Truck Intake


6.0L + 224/224-108ICL + Truck Intake


5.3L + 220/220-108ICL + Truck Intake


5.7L + 224/224-108ICL + Truck Intake

mattrem

iTrader: (7)

So I quess a manifold with a shorter runner? How about if the mainfold had more volume? And use a 90 mm TB for more air?

Sport Side

iTrader: (6)

Is anyone positive on the runner lengths of the Truck intake?
I heard it was very similar in length to the LS6 intake so, it
may just simply be the design of the thing that is holding us
back. I truly do not know. All I see is proof that something
is wrong. Best thing to do from here is try the swap and see
what happens.

mattrem

iTrader: (7)

I think the runner length is just hear say, Not sure myself. If someone could make a harness to adapt the LS2 TB(6 pin) to the truck (8 pin) I would try this, I mean I will just about try anything, just not changing everything for the LS6 manifold.

Sport Side

iTrader: (6)

That could very well be possible. Look at what has been said
over in the truck sections for the past 2 years. Everyone
thought the LS6 intake would be a waste and that they had
very similar operating ranges.

mattrem

iTrader: (7)

I quess some flow bench work would help also?