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Gollum

180 Degree L28ET Intake

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I need to measure my valve cover, but I think these specs are close:

 

L28etIntake006.jpg

 

I'd changed the radius of the 180 degree bend to 4", just to find that the metal suppliers websites I have bookmarked don't carry that radius for the pipe size range I'm looking at. So it'll have to be changed back to 6" for all of it.

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Latest Render.

 

L28etIntake008.jpg

 

I checked the dimensions of the valve cover last night so my guess would be a bit more accurate.

 

Front height = 5"

Overal Length = 26.6"

Distance down to intake port from lower portion = 7"

 

The new render reflects those changes. I have a bar shown that's where the intake port should be. The tube in the render ends about .5" away from the bar to give room for grafting into the stock intake.

 

My estimated overall length is 17.98". (that's with the extra .5" added to get to the head). Should I be adding some distance for the actual head port?

 

Well, at 17.98" my peaks are as follows

 

2 waves - 8880 RPM

3 waves - 5920 RPM

4 waves - 4440 RPM

5 waves - 3550 RPM

 

 

Cam duration is 240 (stock L28ET cam) and runner diameter is 1.37", or 34.8mm. This is slightly larger than stock, but I don't have much of an option when you're shopping by price.

 

Maybe I'll port the head a taste when I do this. I don't think I'd be removing that much material to get it to match.

 

Today after work I'm going to go buy some play-doh at the $1 store and check my hood clearences.

 

EDIT: 14 guage 1.5" OD comes out to 1.334", which is much closer. It would cost about $130 before shipping. I think I could manage that. I'll be changing my drawings to reflect that change.

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I don't know how it took me this long, but this is why I'm glad I've started modeling this NOW, instead of just a month or less before I plan on building it...

 

 

But my current idea of how to build it to clear the hood is wrong. The engine is angled, so while I'm trying to wrap around the valve cover I have to make the lowest point off axis from the valve cover.

 

Here's my latest attempt to get it to a dimension that looks like it might clear:

 

L28etIntake009_front.jpg

 

L28etIntake009_Right.jpg

 

L28etIntake009_Left.jpg

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One quick update before the insane business of the weekend comes.

 

L28etIntake010.jpg

 

This is starting to look really good to me. If the hood clearence is good enough I don't think I'll change this too much from here on out, except maybe some plenum design.

 

Runner length = 15.532"

 

2nd wave = 10250 RPM (way too high to be seen... EVER)

3rd wave = 6820 RPM

4th wave = 5115 RPM

5th wave = 4093 RPM

6th wave = 3410 RPM

 

I must admit... I don't know how much each resonate wave will help power. I'd assume that the lower waves, like 2nd and 3rd will show much stronger peaks, but I'm completely uneducated in this field... Just a wild guess on my part. I figure the numbers might still mean something though.

 

You can't see it in the picture, but I've also radiused the inside of the plenum/runner transition to .50. Looks pretty neat.

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I think its really cool and all and I too like to desgin stuff like this but I dont see the benefit or gains this would provide..

 

It would help w/ intercooler plumbing, however, the effort to build this far outways anywork associated w/ the plumbing itself.

 

From my understanding, a longer Runner length should help out top end RPMs, but to long will kill the low end.

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It would help w/ intercooler plumbing, however, the effort to build this far outways anywork associated w/ the plumbing itself.

 

From my understanding, a longer Runner length should help out top end RPMs, but to long will kill the low end.

 

I think that's backwards actually. Trucks and other heavy vehicles tend to have long runners to provide strong low end torque, while small displacement engines with high redlines have very short runners.

 

And lengthing the runner lowers the RPM at which the 2nd, 3rd, 4th, and so on waves occure.

 

Though if someone wants to explain why I'm wrong, feel free.

 

The real benefit to this design is that you'll be able to get as much as intake as possible away from the turbo AND it REALLY simplifies the intercooler plumbing.

 

If I'm going to make an intake from scratch (which I wanted to anyways, just for the fabrication explerience) then why not do something different than most people and see how my theories work? This isn't going to be a race oriented manifold. I'm not increasing the runner diameter much (I'd leave it stock if I could, just so I didn't have to mess with the head), so this is really just about an idea and what comes of it.

 

I was kinda hoping someone would have some thoughts on well it'll actually work. A 15" runner isn't THAT long. I think it's not much longer than some of the long runners sceen on this site even (the long ones 1 fast Z/brian makes comes to mind). And on those engines they're going for peak HP numbers well beyond 6000 rpm, and I'm shooting for there or under.

 

Where's braap? I was really hoping he'd comment on what I've got thus far.

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Oops, sorry was drinking last night. :P Yes got it backwards!

 

I think that's backwards actually. Trucks and other heavy vehicles tend to have long runners to provide strong low end torque, while small displacement engines with high redlines have very short runners.

 

And lengthing the runner lowers the RPM at which the 2nd, 3rd, 4th, and so on waves occure.

 

Though if someone wants to explain why I'm wrong, feel free.

 

The real benefit to this design is that you'll be able to get as much as intake as possible away from the turbo AND it REALLY simplifies the intercooler plumbing.

 

If I'm going to make an intake from scratch (which I wanted to anyways, just for the fabrication explerience) then why not do something different than most people and see how my theories work? This isn't going to be a race oriented manifold. I'm not increasing the runner diameter much (I'd leave it stock if I could, just so I didn't have to mess with the head), so this is really just about an idea and what comes of it.

 

I was kinda hoping someone would have some thoughts on well it'll actually work. A 15" runner isn't THAT long. I think it's not much longer than some of the long runners sceen on this site even (the long ones 1 fast Z/brian makes comes to mind). And on those engines they're going for peak HP numbers well beyond 6000 rpm, and I'm shooting for there or under.

 

Where's braap? I was really hoping he'd comment on what I've got thus far.

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Way wicked Gollum!

 

Have you considered putting the injectors on the final turn, on the outside, pointing toward the head?

Might be easier to get at and to fabricate?

 

In my first version I had the injectors up there, but I'm not exactly liking the idea. It really complicates things having them out there. If I just use the stock location it'll be that much less I'd have to fabricate and make sure I engineered correctly.

 

Oops, sorry was drinking last night. :P Yes got it backwards!

 

No harm no foul. ;)

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Hey I was just out looking at my car and I realized that I have a strut bar... it got me thinking of how many other people have strut bars. I have the MSA adjustable one, but there are many others out there. Maybe you should take that into consideration as well.

 

Like I said, I'll buy one, but I don't want to have to lose my strut bar. So if you could design around that too, I'd be happy. LOL.

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Is there going to be enough room for the injectors in the stock position. I understand you left room for the flange in your renderings. But an injector with (I'm guessing) a pallnet style fuel rail may be a tight fit.

 

L28etIntake009_front.jpg

 

 

 

Kevin

 

Yea I've been thinking about that. I could easily make the bend near the hood a few less degrees, then add the same amount to the last one before the injectors, and add any length between the two bends, or after if needed.

 

I'm waiting to get some more dimension estimates to revise the drawings. Once I have a better Idea of how much space needs to be given I'll be able to adjust accordingly.

 

 

Astral Ace ~ I don't think I'll be making these to sell, unless someone want to pay me $600+ for it, as time isn't something I have a ton of lately. I'll gladly make any plans and blueprints availible though, even links to suppliers I go through for the metal.

 

And as far as the strut bar goes, I'm not sure what conflicts there will be yet. I know there will probably guarenteed be SOME issues with most bars, and I just have to figure out where to see what can be done. No worries though, I HAVE thought about that.

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I'd place the injectors on the outside of the radius, you'll be surprised just how long the last part of the runner going to the head will need to be, to clear the injectors and fuel, along with actually being able to service the injectors.

Also the farther up the runner the injector is, the better the atomization can be, at higher RPM. Nearer the head for low RPM and idle. This also seems to efect low RPM emmisions as well.

 

This also seems a LOT more involved than just running that single 3" tube from one side of the car to the other, behind the rad, in front of, where ever. I don't see any real benefit to this other than building some great bottom end torque with the LONG runners. ;) If you're trying to reduce heat soak, the plenum will have less heat soak, possibly, but again, I'm still not sure it would be that much benefit.

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Wait wait wait wait WAIT!!! :)

 

Center the TB flange on the plenum, facing down right in the middle, and make an A frame box tapering to smaller vloume out by cylinders 1 and 6. You want even distribution, there you go. You could PROBABLY even install some air combs similar to what monzter did in his intake plenum.

 

Ford Escort, mid 90's, the intake runners are long curves.. you MIGHT be able to get away with using those as stock, but looking at some of your later renderings I don't know. You HAVE seen images of the LD28 intake manifold, right?

 

EDIT Regarding the strut tower bar, I *think* theres a good chance that the spacing between #3 and 4 intake runners (in other words, the spot on the head where the 3&4 exhaust runners are) should provide a spot to run a strut tower brace bar through there. I need to find a picture of the bar I have in mind, but there is one with a C-shape mount, and an ear that comes up on the hind side of the mount. If the bar is mounted on the back side of the ear it should be kosher.. as long as the plenum sits low enough. END EDIT

 

 

 

Now, I have an interesting idea that I am curious to know the impact of....

 

What would the result be if one were to build a manifold along these lines, with a balance tube uniting all six runners near the head? I haven't got a clue, but it was one of my first thoughts when the subject of "how long those runners are!!" came up.. (the better to torque your n*ts off, my dear!!)

 

Me LIKEY this idear!!!! You could possibly even run a set of 45* tubes to a single flange pointing skywards, install the injectors on the fender side of that flange, and have it bolt together so it would be easily removed for valve cover (and spark plug) access.

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I've thought about all that's been brought up, so sorry if I don't adress every little comment.

 

Oil Cap ~ I think it'll be far enough forward to clear. I'm not positive on that yet, But it's a hope...

 

LD28 Intake ~ I've seen the marine one that enters in the middle. Is that what you're talking about Daeron?

 

I'd thought about having the TB flange in the middle, I just wonder if it was worth the extra inches of intercooler piping. Thinking more about it I think it is. Even distrobution will not just help keep the power smooth and safer, but should help low RPM driveability too.

 

Balance tubes ~ I'd thought about this idea too, but I'm hesitant as I'm not sure how that will affect the induction wave runing of the runner length.

 

Six Shooter ~ duh it's more involved. That was never the reason. I didn't think it would be LESS work, just a simpler, cleaner airflow design that reduces heat soak and makes the turbo easier to get to and work on.

 

Remember as I said before, that I think not only will the plenum have less heat, but the turbo will get more air to it. The stock setup leaves very little room for the turbo to breathe. Though some would argue (rightfully so) that a heat blanket on the turbo would see almost all the same benefits.

 

But where's the fun in that?

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Six shooter and others were right about space for the injectors, they just won't really work in the stock location. Oh well.

 

So I modeled an injector that's pretty close to spec I think (going off of specs I got from MSD's website), and also modeled an injector boss. The main reason I didn't want to go this route was cost, but it's cheaper than I thought. I found bosses at many websites for well under $20 a piece, most around $14-$16. Idealy I'd like to find them for less than $10, as even $60 on bosses really hurts the $300 budget.

 

I also modeled a clamp in there so I could get an idea of what clearence would look like. It's not bad. I'm still not sure I like the idea of clamps. Clamps mean that

 

A) More cost

 

B) I HAVE to make a braket to support the plenum side

 

C) One more thing for air to catch on

 

D) More cost!

 

If someone can point me in the direction of a good junkyard clamp around the right size I'll see what I can find. Otherwise I'll be searching the net for something affordable.

 

Oh, I almost forgot. The latest images:

 

L28etIntake011.jpg

L28etIntake011_2.jpg

L28etintake011_3.jpg

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You're going to need to modify the cam cover as well. I looked at my L28 in my car in the driveway, and the oil cap pretty much lines up with the #1 port.

 

Placing a "balance tube" near the head will destroy any resonance function that you are trying to get, essentially it becomes a plenum, a small one, but that's how you would need to think about it. I'm not sure what the purpose of that "balance tube" would be.

 

I would change the location of your TB flange in the last renedering. You would lilkely end up with the TB being VERY close to the engine mount, inner wheel well, wiring, etc. Probably also need a very tight bend to get and intake tubing to mate up. I would place it on the "top", basically 90 degrees from where it is, this will make IC tubing a little easier to connect to, probably also make throttle linkage a little easier as well.

 

I'm still thinking hood clearance is going to be an issue.

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