CopMagnet

Look for a bullseye stamping as well. It's visible from the top through all the other junk. Bullseye stamp denotes LS1. Or get one of those mechanic mirrors to check the block code. I couldn't wait to look at mine last year when I came across a car mag online article on the subject. One thing to consider with intakes, if you go boost, is the 2 part design of a fast.

Paul Bell

iTrader: (9)

The LS6 engine block installed in a F-body car offered ZERO horsepower gains over a LS1 engine block.

The LS6 intake manifold that came in the F-body cars did offer a bit of improvement but was negated by a slightly milder cam in those years.

The real LS6 power gains were realized from the LS6 heads and cam. However, as stated above, there are much better options available on the market today.

The LS6 engine block had improved bay-to-bay windows in the block which slightly reduced oil windage but offered nothing in power.

CopMagnet

^^ Some guys swear there's more power, but personally I don't see how with the same 241 heads, bore and stroke.

RJDio

This is an edited quote from an article and interview of John Douro, GM's Gen III/IV block staff engineer: "First, the LS6 casting was much stronger....and the LS1 block had a 28.5mm vent hole drilled through the center of all 5 bulkheads. Engineers deemed this insufficient for the LS6 block, so a new design with a much larger, cast-in hone-over travel vent window thorugh the 2,3, and 4 bulkheads toward the bottom of the cylinder bores on both sides was created. The results were impressive. Created 87 percent more ventilation on the LS6 block, less pumping loss at higher rpm's. NO OFFICIAL reports of hp gains, but the engineers were optimistic about gains.

I edited about a 6 paragraph article since I'm tight on time and don't feel like typing all day. Fact is; the LS6 block was an improvement. I have no idea if my block is a LS6, but I'm curious to find out.

john.kiley

Exactly, I can 100% confirm that not all ls6 intakes are without egr because my 2000 z/28 has one, and it came like that, was not added on at a later date.

RPM WS6

iTrader: (3)

There were no LS6 intakes in regular production for the 2000 F-body model year, so it would not have come with one from the factory and was definitely added post-production if it has one.

As for the LS6 intakes themselves, as mentioned in the post you quoted above, there was a time when SLP was selling them with an EGR provision already added (for fitment on 2000 and earlier cars). But the intakes didn't originally come that way from GM, nor were they an SLP option for new production vehicles (this was aftermarket only, via SLP Online, not any sort of original "Y2Y" option).

john.kiley

How do u know forsure there were none? Mine was a late 2000, also it is a Canadian car maybe there is a difference? Anyhow the guy I bought it from was the second owner, can’t be sure it wasn’t added on later but I would be surprised considering how « factory » it looks and just overall patena of everything looks equal in the engine bay.

RPM WS6

iTrader: (3)

They were all (4th gen F-bodies) built in Canada - but are you saying yours is a Canadian-spec car (meaning originally sold new in Canada)? Even still, the LS6 intake was not issued from the factory on 2000 model year F-bodies, even the late ones that might have received the upcoming 241 heads (of which there were a few). GM did not issue EGR with the LS6 manifold but, again, at least one company (SLP) did sell them (aftermarket) with this provision many years ago, for easier retro-fit onto the older models. No telling what might have been added to your car earlier in its life by owner #1 or #2.

john.kiley

yes sorry it’s a canadian spec car. I know for a fact the second owner didn’t add anything to the car, maybe the first owner got the stuff added then...

440_Stroker

Yup. The LS6 intake wasn't available on any car till 2001.

john.kiley

Any difference from conventional 01+ ls6 intake cars? This is my 2000 w/ ls6 intake and egr

RPM WS6

iTrader: (3)

That looks exactly like the SLP-modified LS6 intakes that were sold (obviously by SLP) back in the early '00s for cars that needed the EGR provision (such as those which needed to pass visual emissions inspection). That brass piece is not a GM/factory EGR provision, therefore certainly not stock/original. We put one of those intakes on a friend's '00 Z28 back in 2002 or '03.

So I think we have solved the mystery - either the first owner bought that intake from SLP many years ago when these were still sold (or bought it used), or he modified an LS6 intake in the same way that SLP did for their aftermarket version.

john.kiley

right on thanks for the info, very interesting

RevGTO

iTrader: (12)

Yes, this has been verified once again and as RPMWS6 pointed out, the EGR connector at the manifold is a dead giveaway.

The reason this was never done was that it was not just a matter of using one intake versus the other. The change to the LS6 manifold in MY 2001 was coupled with a cam change, all of which required the Federal emissions and fuel economy certifications. This was done on a model year basis, so no new intakes with the old cam on 2000's.

So my 2000 FB is late production - June 2000 - and has the 241 heads and other running changes made late in that model year. Yet it had the LS1 intake. Replacing it with the LS6 back in the day gave me a nice bump in mid-range torque, probably about 15 rwhp, and knocked .15 off my 1/4 time