On top of that if you ever compared a LT4 to a LT1 in cross section you would be scared.

The stock LT1 intake is not half bad, and only if you are really twisting the motor are you going to find lots of power on stock cubes, more cubes the more you need to fix the intake.

Bret

 

So you are saying the LT4 in stock form is worse as far as cross section?



Nick

 

I was hinting at that ;-)

 

That's why I had a professional port mine I figured that I would do more harm than good if I tried it myself.

 

If your question was asked, with your concern pertaining to the oem LT1 intake, for the vehicle,
in your signature in particular, then no, the ports of the two intakes, would be virtually identical internally. In this case, unfortunately, you need to be more specific.

If you look at it from a positive viewpoint, at least the later model intakes line up better (less mismatch) with ports in heads.

 

Be more specific about what? I asked Bret if the LT4 intake is worse compared to an LT1 intake as far as cross section and he said yes. I believe in his earlier post he said "you would be scared", and "thats what I was hinting at". As far as my application goes, my LT4 intake has been welded up by the injector bungs, then fully ported. With out all of that weld there would be no way to raise the roofs far enough to get the cross section even close. I was amazed to see the before and after, not to mention to see a mountian of aluminum shavings on the bench. My injectors are right up against the intake/weld, you cant even get light to pass behind them. In my opinion, this is a VERY important step in getting these intakes to work right, especially on stroker motors. With all of the talk around here about so and so heads flow 2 more CFM more than the other guys heads, a very important piece of the puzzle is being overlooked.



Nick

 

Apparently you didn't read MY post, very well. I stated, not all LT1 intakes are cast the same. I did NOT state what Bret posted, is in error. But, I did state, that it can be/is model year sensitive. I'm not stating, I've a problem with that. In the past, I've stated info, that was model year sensitive, as well. I'm actually in agreement with Bret. What Bret has posted, and more, has been posted by me, a few times, a long time ago. Have no idea how much is still available in archives. Alot of regurgitated material gets discussed on this forum.

My injectors are right up against the intake/weld, you can't even get light to pass behind them.

This should be a clue, this is not the correct/professional approach to correcting the 'flaw' of this design intake, IMO. It IS popular, however, and has been accomplished by some, this board respects, along with other 'so called' professional porters, in the past. Course, utilizing the extra as cast material in/on the port roof, of the LT4 intake, is neither. That is just taking advantage of a GM 'band-aid'. But that is a separate/different issue.

 

Then what is the correct/professional approach? My engine builder that has been building competition racing engines for over 33 years begs to differ on your opinion, as do I. We both felt for the time and money spent its the best way to go, after that, start modifying a single plane or go the sheet metal route. If there is a such a thing as a correct/professional approach to modifying a LT1/4 intake, please post this information and eduacte us all. I wish I could have taken before and after pics of my intake work, as I would have been more than happy to share them with CZ28.com.



Nick

 

I am not an engine builder, so I don't know the ins and outs of manifold design. I did however, clean up my intake manifold ports. I didn't reshape them much, I just used some cartridge rolls to smooth them out. I can't see how it would hurt. It doesn't take too long. I don't know how much this will help, but the ports do look nice...

 

I'm confident, that he is confident he knows what he is talking about, so you are probably better off listening to him. 33 years is alot of experience. Besides, appears your mind is already made up.
I'm refering to raising the intake.

 

Hey Arnie, yes, in a sense it was made up, because for the money invested into what I did it was the best way to go, and did help out with a major "pinch" or restriction in the factory configuration. Like I said, any more $$$ and I would have been on the phone with Hogans or Wilsons. I completely understand about what you are saying with raising the intake, as a few inches more in the runner area would certianly help, as 3 isnt enough. I would love the idea of using a modified Victor Jr, or some type of tunnel ram with a box on top, but I have a feeling my next phase for this motor in a year or two will not include my AFR's, or any other 23* head.


Nick

 

Based on your 'few extra inches' comment, is clear to me, that no, you do not understand. The extra runner length would also help, but for different reasons, however no bearing on what the intent is, or purpose here, for which raising the intake would be done for. Hopefully, rereading my previous posts will be of aid here. If not, here is an opportunity for your 33 year man to make use of his experience, to explain it in more detail. If not, maybe his 33 years of experience in engine building, in which he is probably proficient in, did not include subject of airflow, and how the manifold/plenum ports are but extensions of the ports in the heads. How they direct flow into heads, has a bearing on how effective the head port contour can be. Either they can work with head ports, or work in spite of.

The LT4 manifold porting (a good example) that is popular on this site, even though gains are recorded, AFAIC, causes the manifold ports to work in spite of.

 

Well Arnie, according to you it seems like I dont, and neither does my "33 year man". I guess when you look at AFR's website, under dyno tests, and look at 406ci Chevy Dyno Packages Power at Flywheel, seems like he doesnt have a clue (by the way, AFR low balled his dyno figures by about 30, in the event other shops couldnt duplicate his package/figures). Runner lenght is just one thing that I mentioned, as plenum volume is also needed, as well as other areas need to be addressed. As I stated earlier, for the money and time invested, it was the best route to go. If had about 3 grand laying around, I would have something from Hogans under my hood, along with heads that have less than 23* of valve angle. How about posting the links to these post so I can read up on them, as I do not understand to even use the search feature. And please post in English, as wording your post that read like the fine print of the bottom of a legal contract is really a waste of time, please, just facts on what work and what doesnt. Look at some post from fellow board members like Bret, his father, Mindgame, you will get the point.


Nick

 

from what ive seen on the dyno, i think it has less to do with the differences in port cross section area and more to do with the plenum volume of the LT1 intake not being able to support a larger displacement shortblock above a certain rpm.