circuiticon

Hi guys,
I'm new to the platform. I built a car with an LS1 swap, and it appears to have an LS2 intake manifold with a 92mm aftermarket throttle body. From everything I've read, the LS2 intake manifold is not very good.

I tried to find dynos that compare the original LS1 intake manifold (not the LS6 manifold) to the LS2 manifold, but I couldn't find anything. I'd be really curious to know.

Everyone is telling me to upgrade to 243 heads, but before I do, I'd like to start simple and get a better intake manifold.

So here are the options I'm finding:

1. Find a used LS6 intake manifold for around $350 and bolt on the smaller throttle body
2. Pick up a Dorman intake manifold (615-901) for around $300 and use my 92mm throttle body with it. I found a dyno chart that compares the 615-900 manifold with the LS6 manifold and it was about 7whp lower. I'm not sure what the difference is between the 900 and the 901, but my guess is the inlet size. I also found this thread which has some flow numbers.
3. Get a FAST 92mm intake manifold (54039B?) for around $900 and call it a day.

My ultimate goal is around 450hp.

G Atsma

The 243(or 799 which is an identical later version that comes on late 5.3 truck engines) would be your best move. The LS2 manifold, though not great, is still better than the LS1. I would get the Dorman LS2 manifold so you can use the 92mm throttle body. A little work with a Dremel is known to really wake up the Dorman. Mainly cleaning up casting flash or other hiccups near the ports.

HCI2000SS

iTrader: (2)

450 at the motor or wheel?

circuiticon

So those heads look like they go for $300-$450 per pair used. That's not much more than the Dorman intake mani. Hmm, should I do the heads first? Besides gaskets and head bolts, what else will I need to do the heads? Rockers? Pushrods? Springs? I wouldn't mind a higher rev limit.

From what I'm reading, I'd be expecting a 25whp gain from swapping to those heads. Not bad, but not as much as i would have hoped for.

I'm guessing I'll need a cam to really wake it up?

circuiticon

At the crank.

I don't know much about the LS, but I'm hoping some 243 heads (possibly ported), maybe the FAST intake manifold, and a decent cam will get me there.

HCI2000SS

iTrader: (2)

If all you are looking to do is 450 at the crank just the typical bolt ons and cam will do that, even with the stock heads and intake

circuiticon

Really?? What are the "typical bolt ons"?

I should mention that due to fitment, I'm stuck with using 1 5/8" headers unless i feel like spending a lot and doing a lot of fab work, so that will limit me.

HCI2000SS

iTrader: (2)

Ok I didn't know about the header issue, but even those should get you to that goal. Typical bolt ons include a full exhaust system, some type of cold air or ram air induction, underdrive pulley, ported throttle body, tune, etc...Even with those headers and the LS2 intake making close to 450 at the crank shouldn't be much of a problem with the right cam and a good tune

big hammer

Fast. Ls6 intake is a turd.

G Atsma

LOL Where have I heard this before??? Deja vu.....

omc8

iTrader: (7)

I don't think you going to see 25 hp at the wheel from stock 243s alone. As far as LS1 vs LS2 there is conflicting reports, on those heads up there shootouts that LS1 beats the LS2 intake. I believe the the LS2 shows an advantage over the LS1 at .600 but around I'd probably go with LS1 .But if talking about a full ported LS2 then that's different story.

circuiticon

Just an update - the car looks like it has injector adapters on it which convert from the rectangular style jetronic on the harness side to a more oval style for the injector. The injectors are black with a blue band at the top, and appear to be stock LS2 injectors.

So if I had to guess, it seems like someone took a stock LS1 and bolted an LS2 intake manifold with injectors to it.

It looks like the LS2 injector is about 32-34 lbs/hr

It looks like the LS1 injector is about 28lbs/hr

Is this correct?

If this is the case, I want to keep my (what I assume to be) LS2 injectors?

G Atsma

What is it tuned for?

circuiticon

I'm in the process of tuning it now, and I'm looking for scaling data.

SLP IROC-Z

iTrader: (14)

there should be a part number on the injector you can look up. 98 had 28s, 99-00 had 26s, 01-02 had 28s

circuiticon

2569113

Apparently that's a 32# injector.

circuiticon

I downloaded a stock 2006 GTO ROM which should use those injectors. I copied and pasted the values from "Flow Rate vs KPA" into my 2004 ROM. It still feels like it has 100hp.

omc8

iTrader: (7)

There is an old Hot Rod article where they tested all the oem intakes at the time. In that test the LS2 only gained 1 hp and 4 tq over the LS1 intake . And the LS6 only gained 2hp over the truck intake. Here is a part of it ....... " Duttweiler tested the original stepped-floor LS1 intake (stock on ’97-’01 Corvettes and ’98-’01 F-cars), the flat-floor LS6 manifold (also used on most LS1 builds from late ’01 and up), and the Generation IV LS2 intake. Compared to the LQ9 truck long-runner design, the LS1 intake lost 9 hp and 11 lb-ft. The LS6 intake was a hair better, but certainly not enough to justify the complexity of the changeover unless you had a hood-clearance issue. As for the LS2 configuration-fahgetaboutit! Despite a larger 90mm throttle body, when compared to the best headers/cats/truck intake configuration the LS2 manifold was down nearly 8 hp and 7 lb-ft at the peak and 6.7 hp and 9 lb-ft on average."

Bill00Formula

iTrader: (4)

I would go with a FAST. A long time ago I added an LS6 to my bolt on car and saw no improvement. I would think that would change as you modify your car. I have a fast 90mm if your interested.

circuiticon

Thanks!