WRT to the LS1 and injector positioning, it’s really all about that funky opening that the ports have. That tall, pointy shape is what allows the injectors to be positioned and aimed well at the backs of the heads.

I’m not sure that I see the difference in the positioning with the MM sheet metal intake and the stock intake…

 

Good points about the viscosity... I was thinking openly (mentioned in the thread) but it is good to correct the wrong statement. Thanks.

I thought the injectors were 5v injectors that were ground side controlled. My mistake. Thanks again.

 

Wild1, if I gave you the impression that I was picking on you I didn’t mean it that way, I was just trying to get correct info out.

And yes, they are switched on the ground side of the circuit.

 

No worries... it's been hell on the homefront. I just wanted the correct data too. Thanks.

 

Actually, if one would look closely at the oem as cast opening of the intake ports, in the LT4 heads, a subtle and very diminished dimple can be observed at the top of the port. This is to allow clearance for the injector spray as well. I did state subtle however, for it is obviously not the dedicated/serious 'tall pointy' inverted V shaped clearance that can be observed in the LSx intake ports.

I may have implied the superior injector/port angle relationship of the LSx heads was entirely the result of an improved intake port angle alone, but I agree with you, the oem did what they could, within space constraints, to change the angle of the injector itself, in the intake manifold as well.

 

does anybody have a link to good pictures of the LS1 intake and head?

 

Has anyone thought about producing that same dimple in the LT4 heads as the LS heads have to get better injector positioning? I should really look at this at the shop. It seems that it would help the fow along the top part of the head and intake port is you could physically move the injector up in the intake manifold and still give it a good shot down the head port.

Somewhere around here I have the angles of the injector holes. I know the LT stuff is angled about 5degs or so in at the inside of the port and rolled about 7 or so back (if I remeber right) and the LS stuff is much more drastic than that. It's like 23 degs toward the inside of the port, and 11 or so back.

Don't quote me on that but that's about what I came up with.

Bret

 

Check out SkarodoM's AI site for some head shots.

 

Donno about you guys, but I'm about ready to pull the injectors out of one of the LT1's sitting in the garage and take a really serious look at what I see wrt to all this...

On that note, anyone know where I can get a relatively cheap LT4 intake?

 

Observation: LSx 13° heads seem to work better than Bowtie 18° heads, both of which do better than any 23° head.

Conclusion: Shallower angles seem to be better for flow or enhance combustion chamber geometry, thus increasing volumetric efficiency, making more power.

Following this conclusion an ideal head would have a 0° angle, meaning the valve would be straight up and down and the combustion chamber roof would be flat. Obviously that's not right, though, but I think it's safe to assume that shallower is better up to a point.

Where I'm going with this is this: shallower angles seem to complicate injector positioning with respect to the intake manifold. Why has no one considered putting the injector bung on the head as opposed to the manifold? Engineering difficulties? I'm not talking about a direct injection setup (although that might be ideal), just simply putting the injector directly on the head, in line with the intake runner, aimed at the back of the intake valve.

Is there some overriding reason this isn't done? Would it offer no benefits? Would it be dangerous? Packaging problems?

 

Heat?

 

GM put injector bosses in some of the later 3.8L V6 heads, but I suspect that they did it for a different reason, to make room for an eaton blower.

Flattening the valve angle results in a number of complications, the biggest of which is it starts making valvetrain geometry much more complicated and the whole engine gets bigger

 

How about putting the injector in the combustion chamber as in a direct injection setup like Audi's R8 race cars. Then all you have to deal with is dry flow. One day this will be common place in street cars.

Bret

 

My guess is packaging. My heads have guideplates and there is less than 2 inches of room between them over the runners.

Could somebody measure the diameter and stuff of a typical injector?

I wonder how modern diesel fuel injectors would work for gasoline? Direct injection diesel is common now. I betcha those injectors ain't cheap though...


I had another idea that might work...
in school we had an early Vortec V6 in a Blazer. I think it only had 1 or 2 injectors. The "spider" injection on it had all the fuel injection stuff inside the upper plenum. Plastic lines ran from the injectors to the head through the ports. Please excuse me if I'm totally wrong on this since it was a few years ago that I looked at it.

I wonder if something like this can be done for the LT1?
Maybe move the injectors away from the intake a bit and have plastic lines (or aluminum tubing) go from the injectors into the runners?

Or go even further by cutting the top off the plenum to increase the size and putting a custom fuel rail and the injectors INSIDE the plenum.

This would let you expand the plenum out sideways because the fuel injectors and rails would no longer be in the way.
This would easily let you double the plenum volume without adding any height or getting into the IAC passages.

I would make it a 2 piece intake so you would be able to get to the bolts that hold the bottom to the heads. Anybody that would go this far would probably have a cam with enough overlap for self-EGR, so that area in the back of the intake could even be used. I would also consider moving the vacuum ports to back there to clean up the looks under the hood.

In another thread I mentioned that I wanted to convert a larger single blade throttle body to the LT1 intake. This intake would make that easy to do.

You might even make a sleeve for the injectors to go in to smooth the airflow around them.

I do plan on doing this for my LT1 if I keep it. It'll be a good while until I have the means to do it. Oh yeah, I'll have another 4-5 inches of hood clearance that I'll be able to take advantage of

 

Hey you ever think what Al Cordas LS1 F-Body must be turning out? You get the LS6 heads on that motor, I figure he could be close to 500rwhp on that combo with those heads.

All of these numbers are pretty crazy when you think about it!

2905lbs full interior, and he ran a 9.9!!!

Bret