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180 Degree L28ET Intake


Gollum

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Kinda Reminds me of the P65 Nissan Intakes on JDM vehicles like the Leopard and Cedric. They were on both L20E and L28E's.

 

Runners wrapped around under the plenum, around the outside, and actually airflow entered the runner on the top or on the valve cover side of the plenum. Someone posted some photos here, I'm sure. There is a removable piece on the plenum.

 

Awesome, I found the pictures. I'm going to post them here as well. Thanks for the heads up tony. Some good reading in that thread.

 

p651.jpg

 

p652.jpg

 

It's a nice and compact little manifold. I'm amazed at how sharp those bends are though!

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Here's another mockup/new design. This is probably a bit closer in design to what would actually get built for these reasons:

 

1: Easier to work with assembling panels vs round plenum

 

2: Multi curve runners to keep the runners close to the valve cover without making contact.

 

My runner length is 29.0465, darn close to 2nd wave calculations for 5500rpm

 

1st bend is 4" radius, 2nd is 6" radius.

 

L28etIntake004.jpg

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A thought I had was to do just the oposite, make the turbo header go over the valve cover and keep the intake lower. This way the heat is rising away from the intake.

 

Of course, a custom intake would also be necessary. Not exactly sure if it would work, but was just a thought.

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That thought hadn't crossed my mind... sounds extremely complicated if you ask me. You'd end up with the manifolds crossing and things might get messy. Not much space to cross them.

 

If you're trying to move the turbo... you could move it to the wheel well... :D

 

I'm on a tight budget though, so a custom exhaust manifold hasn't been in the budget from the get go. As soon as I started learning about the torchable aluminum solder ideas started racing through my head....

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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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