Brainstorming a new intake build

[DesertSasquatchXploration]

If the type 1 dual port castings on a center mount carb setup are the bottle neck why not use different manifolds? Stock type 3 are available 60 bucks on ebay I wont be using the carbs of course but... do the manifolds themselves clear a factory dog house shroud? Sure would be nice to have a solid steel intake that bolts on. 34MM is real close to the ID of my 1.5 inch intake.

If that wont work Dual IDF manifolds. The whole setup would be on top of the Generator Hang way out and four runners would be way over kill for my needs but could be done I think. You would be looking at the carb in the back window.

I'm guessing VW did the dual port end casting the way they did with the separate runners for a reason. I could see a dead spot in air speed once the intake tube dumps into the Plenum of the type 3 manifold.
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Key is to have downward travel Preload keep both wheels on the ground at all times once you lift a tire your DONE. Guys worry about clearance instead think of the opposite you want the suspension to drop that tire in the hole and keep you going. A spider for example they keep their body low but their legs can reach pretty far so they don't (bottom out)

[modok]

Type 3 fi manifolds are about 28/29mm I'd
The bends are about right, I make some into sp manifolds.
It might be able to fit with a Mexican fi alternator stand.
Dp end castings ate actually a bit larger.
If the are a bottleneck, that depends what heads you bolts them on.
Larger ones do exist but you best have a 82 stroke to need them.

Watch this
https://youtu.be/zgUHxirCos0?si=o0HLnAWLSY3ewbzG

[DesertSasquatchXploration]

That was great. I wondered about the exhaust ports on a stock heads they (step) open inside. I've heard you don't want to mess with the exhaust ports it will flow worse now that makes sense
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Key is to have downward travel Preload keep both wheels on the ground at all times once you lift a tire your DONE. Guys worry about clearance instead think of the opposite you want the suspension to drop that tire in the hole and keep you going. A spider for example they keep their body low but their legs can reach pretty far so they don't (bottom out)

[rayjay]

Steel kadron manifolds are readily available. I bought a set for a future FI setup with a central single throttle body. Steel fuel injector bungs are available.

[chrisflstf]

With those kadron steel manifolds, you could design a center section that went up , instead of flat to the center section to help avoid pooling in the center section, but if you had FI on the ends, it would not matter if horiz or not.

Sounds like a future project for my side draft DCOE

[NJ John]

I remember seeing drag cars In the 80’s-90’s magazines with probably hilborn injection and a turbo. With Ida or idf intakes and custom piping bolted to the top of them.
Start with Dcnf intakes and make a bolt on transition.
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1973 standard, yellow, lowered, 3” narrowed front, 1600 blo-thru turbo w/single dell 15.4@86, so far
11.41 et buggy. Long gone
Let’s go O’s! Let’s go O’s!
https://www.youtube.com/@AirSpooledGarage

[DesertSasquatchXploration]

OK??? I was asking if the type 3 manifold's fit the type 1 with a full width doghouse shroud. Ill just ask Danpa thanks a ton.

So the 34 EPC empi kits use the type 3 manifolds?

_________________
Key is to have downward travel Preload keep both wheels on the ground at all times once you lift a tire your DONE. Guys worry about clearance instead think of the opposite you want the suspension to drop that tire in the hole and keep you going. A spider for example they keep their body low but their legs can reach pretty far so they don't (bottom out)

[modok]

Oh, I'm sorry I thought you were discussing the type-3 FI manifold parts
Yes those PDSIT manifolds will fit on a type 1

[DesertSasquatchXploration]

[SGKent]

you want to tune the intake length to the RPM you plan to run your engine at. The higher the RPM the shorter the resonance length.

VW used long manifolds probably for 2 reasons - (1) the carb would be cooler the farther it got from the head, and (2) VW was not after a high RPM engine - they were after a moderate torque engine for daily street use.

Many modern high performance engines use variable length intake systems. A longer path is used at low rpm and a shorter one at higher rpm. There are technical papers out there how to tune the length to the rpm and displacement etc.. Same for the exhaust.
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"Most people don't know what they're doing, and a lot of them are really good at it." - George Carlin

[modok]

Well....that hardly does it justice.....
just read some books eh?
I read perhaps half of the literature on the subject, at least what was available before about 2005, and I still have many questions.
Many mysteries, and every year or two I learn the answer to one.

Like, why dual runner length intake manifolds aren't used more often......
(tho miata and a famous honda v6 did have them for a year or two) well heres a clue
If you BOOST low rpm torque on a FINELY tuned engine.....it would just get into knock at lower rpm..... so what's the point? They already have that problem in a lot of racing engines, it would just make it worse. So Lets have variable CR too, and varaible duration, it's too complex for my taste.
Your CR isn't variable, the port sizes and valve sizes aren't variable.
I think variable length intake is...... a solution looking for a problem.
The only problem I found that actually makes sense, is to boost low RPM torque until the turbo spools, so switching to the short runners would be boost activated, not RPM activated. IMO it's a no brainer. short runner manifolds work GOOD with boost, long runner manifolds work good NA to boost torque........
But as of now, not enough people have tried it to find out how useful that would be and sing the praises or lament the.....whyever it maybe doesen't work.
of course just slight telescoping trumpets controlled by servo to stay in the harmonic would work, F1 tech, but......it's not huge, but I guess that's a good idea.

Most really good manifolds are discovered on accident or by intuition, and then we figure out later why they work good, if ever.

Why are the best ones made like they are made.
becase it works.

But why does it work? Well.....Darren Morgan did a great job of answering a few riddles. But you'll miss the answer if you don't understand the question. the first 45 minutes is devoted to why usually the manifold hole is bigger than the carb, which is a question asked hear several times a year, (people wanting the IDF manifold to exactly match the carb)

He said in most good systems the carb is 5-6 inches above the runners and I'll never forget that, because I've been observing/wondering the same thing myself for many years, it got sucked into my brain.
It really appears to me the best design practice, when you have something besides a straight shot after the carb, is to turn 6-7 inches below the venturi, OR if that is not possible, just turn directly under the carb. There should be no advantage to be had in the middle or with a swoopy turn or any other way. And the turn should probably be a converging turn........

Now maybe you you never asked the question..... but now think about it, no matter if it is Torben modifying kadron manifolds to get more height between carb and where it splits, or why IDAs and tall IDF manifolds work good, or why berg manifolds work good, or why the CB low profile manifold works good, go ahead, look now you'll see it. It's the same thing
Find me a book that explains why

Well, some of us hope that....once you know how/why it works then that might give you an idea or another to try.

We HAVE to learn a little, rather than testing the same thing over and over and another guy asking the same question every year.

the last guy from Japan looking for manifolds to match the 36IDF carbs......somehow ended up just going right to berg manifolds....and honestly I'm jealous, jealous of these guys that just have no opinion and JUST go with what works.
But also I bet they rarely invent anything, so it's us stubborn blockheads actually inventing the stuff that works, tho mostly by accident.

I could go on.....but, like I said about questions......