A couple of things:

First, I'm not buying the "more flow is bad for smallish motors" argument because if that were the case then (A): there wouldn't have ever been any justification for GM to build an LT4 intake in the first place, and (B) LSx guys wouldn't be kicking our asses by running 60cfm MORE and 4 LESS cubes than we are.

Second, it's time to think outside the box and get creative. If GM proved anything with the LS1 engine, it's that how much air you flow is only as important as HOW you flow it. Any LTx intake can be made to flow as much air as an LSx, but it's the difference in power curves and driveability as a result of HOW each intake delivers the air that makes the Lsx come out on top. Is it any wonder that an LT4 intake isn't just a hogged out version of an LT1? Could it be that GM took things other than just flow #'s into consideration when they designed it? When doing a compare/contrast, do you notice a trend that formed between the evolution of the LT1 to the LT4 to the LS1 intake?

Third, and I don't mean to offend anyone by this statement because I'm an LT1 owner myself, but it's this dangerously old fashioned thinking that "big flow #'s only belong on big engines" that is keeping the LT1 guys firmly locked into "underdog" status.

 

Flow is not stready in an engine, but rather elastic and too large a port volume can and will lead to a slower start on airflow due to greater mass of air having to be accelerated, not saying the LT4 stuff is in that catagory, just pointing out how very flawed your logic is.
The LT4 intake is not very different nor does it flow more than an LT1 intake it has more material on top of the ports to help in allowing it to be made to match the raised ports on the LT4 heads.

People such as yourself are the problem the LT1 has. With your "LS1s rule" mentality and thought that we have to copy as much as we can from them. That is why the comparatively weak aftermarket for the LT1 even LT1 owners worship the LS1. Furthermore it is people like you and the magazines that keep the LT1 an "underdog". Everyone is so brainwashed of the LT1s inferiority that few show up at the local track though the few that do seem to get attention after they run, mph might not be real high but the ETs are quite good. Before my headers this last summer I actually had someone ask if I was spraying my Caprice, another local stroker LT1 runs deep in the 12s with a driver who sees little track time and was actually built by a basically unemployed mechanic.

 

Are talking about some of us saying that the LT1 heads are a better choice for a 350"? If so, it is not a matter of big flow numbers at all. It is a matter of big cross sections/lower velcity intake ports that make the LT1 heads quicker on a foot braked, low RPM (like a 3500/3600 converter & 6500/6600 RPM shift points) 350" A4 car like most guys have. I'm not talking dyno numbers, we don't race dynos. If you have an aftermarket engine management system, enough cam to make power well past 7000 RPM and enough gear to operate there, then well ported LT4 heads & intake (or other larger aftermarket set ups) would be a better choice.

One of the top cylinder head men on the planet told me there is not as much difference in CFM between the two ported factory castings when flow tested with the the factory intake manifolds in place, as you would expect. There is much more to it than CFM.

 

Actually, I guess I'm one of those "LT1 ownning LS1 worshipers". I work with many people racing both, and think the LS1 is a better deal. Much easier to make go fast. Hard to overcome the weight advantage of an aluminum block out front in drag racing. That and a factory computer that does not limit you to 7300 RPM.

I didn't start out just wanting to modify an LT1, I was just going to fix a couple of oil leaks in an old car that was leaving spots in the garage floor at my new home. Kinda got out of hand. My wife thinks I should have just put a drip pan under it.

I get that "How much you sprayin' it?" question a lot.

Not a whole lot of same-sized LS1 cars can beat up all of "us".

 

The point I'm trying to make about the LT4 intake is that if it was in fact as useless a gain as alot of people make it out to be then there would have been no justification for it to exist. The fact that it DOES exist means that there IS the possibility for an improvement to be made somewhere. I think people tend to get too caught up in peak hp #'s and track times when considering whether an aftermarket intake would be an "improvement" over a stock LT1 intake. This I think is where their logic is flawed. The reason that so many people are defecting to LS1's is not because LS1's have the ability to make more power than LT1's, it's that you have to sacrifice so much more in the way of driveability, gas mileage, idle quality, etc. with an LT1 to achieve the same #'s as an LS1. These are the things that don't get mentioned too much when somebody posts a thread about their new and improved track times. Does this make them any less worthy of consideration though?
The fundamental difference between how each of these engines behaves in relation to whatever mods are thrown at them is HOW they deliver airflow. Really, that's all it is. I'm not talking just peak cfm flow capability either, but: runner length, runner shape, plenum volume, port dimensions, port SHAPE, etc. All of these issues are not something that can be easily addressed by a guy hacking up LT1 intakes in his shop and taking a shot in the dark that his hunches are correct and hoping for the best. It's gonna take alot of R&D $$$ for something like this to happen, and the only way I see it coming to light is if an aftermarket company decides to get behind it.
Once again for the LS1 haters: the improvement the LT1 needs is NOT in it's ability to make peak power #'s, but HOW it gets there.

 

Here is the point flat plain and simple. IF you REALLY want to make the power an LS1 does out of an LT1. PUT 15* heads on it that the Taller deck and a few other minor things make the LS1 a much better platform then the LT1. THAT is where all the power comes from not the intake

Then again the four bolts per cylinder seem to be holding the LSx engines back just a hair at the moment

BTW ALL the LT4 intakes I have "Hacked" up were pretty much Identical internaly to a LT1 intake save for a Dip at the bottom of each port where the gasket meets(that needs filled) and some extra material over the port to seal to the higher port heads. It is easer and cheaper now just to buy a LT1 intake and weld it up to be port for the LT4 heads

THE ONLY Reason it exist is because the LT1 intake would not seal to the heads. GM was releasing the LS1 the next model year and dropped any plans for a better intake on the LT4. Sorry...sad but true

Good luck on your search!

 

I'm sure you have direct personal experience with converting a stock LTx intake to fit on 15 degree heads right?

 

As a matter of fact

 

Was it a pretty easy operation? What were some of the issues you ran into?

 

you build spacers after the heads are converted.

MindGame on CZ28 made 565 or so with his 15 degree heads and LTx intake.

I must admit mine are 18* Brodix heads not 15*. then again they use the same parts

BACK to the original idea here. The LT4 intake was NOT really any different then the LT1 and as far as we can measure it was NOT any bigger. I have 'hacked' a few of them up just to be sure