Custom Intake Manifold Design ?

[Roadkill]

A little way off yet but I've been chatting to a guy who will be supplying the parts and info when it comes to building-up the Cadillac's new motor.

He's answered all my questions thus far but there's one thing he can't do and that's provide an intake manifold I want to use.

When it comes to B.B.Cads' there's basically three . . . Edelbrock dual plane and a choice of two single planes . . all of which are 1 x 4BBL.

I've always wanted a multi-carb set-up (don't ask why) but understand that setting all those up is gonna be a PITA . . . . So I've allowed myself to potentially use FI.

Specifically I want to use 8 x Single injectors hidden in period-style Throttle bodies (as posted in a thread a while back).

My problem is there's no such manifold available, or ever likely to be available.  

That doesn't stop me thinking though.

The design below is a simplistic representation of what I have in mind . . . . One injector/T.B directly feeding one cylinder . . . An ECU controls everything so it should (I'm guessing) iron-out any anomalies between cylinders.

Lugs on the front of each stack is for sensors / future NO2 provision.

Stacks, due to their simplistic design could easily be modified with extensions to achieve the ideal length.



Questions are :

Main issue I see here is complete lack of vacuum - How's best to get it ?

Secondly, this is not my forte so what else am I missing ?

This is how another guy achieved a similar set-up starting from 1 dual-quad adapter, adding 2x 1x4BBL-to-2x2BBL, then adding 4x 2BBL-to-2x2BBL "Y" splitters !!

Unfortunately a dual-quad isn't available for my required application.

[philoldsmobile]

with 8 cylinders running at low rpm on an 8 litre engine, you may find bike throttle bodies suitable, certainly the ducati throttle bodies are going to flow more than enough air (2 cylinders, 904cc revving to 9000, so peak CFM is going to be very similar)

finding four decent affordable used sets may prove more of an issue though. The ducati injection runs without an o2 sensor, so that may simplify things somewhat?

T meister may be able to shed some light?

[Titsy]

Home-brew injection will be a mistake IMHO. Unless you can buy an off-the-shelf solution it will turn into a ridiculous amount of effort for a compromised setup. If you're going to go injection it has to be done right.

If your wanting to go down this route then I would say Webbers or bike carbs are the way to go. I don't mind helping you out with some 3D design tips if you want to model a manifold; I can even throw some software your way... But injection from scratch, I'm running away waving my hands in the air... Ask Edge, that's his department.

[FUBAR]

what happened to that Tri-Carb manifold you have?  is that no longer suitable?  cos that will still look very

[EDGE]

Quoting: Titsy

Ask Edge, that's his department

Hi

[Roadkill]

Quoting: Titsy

Home-brew injection

Not my idea - I said to PhilO yesterday I plan an "out-of-the-box" kit, complete with ECU.

Eg. :

http://www.retrotekspeed.com/products/nostalgia-throttle-bodies/8x2-tb-kit/8x2-throttle-bodies-1-inj.html

Quoting: FUBAR

what happened to that Tri-Carb manifold you have?

That's for a 331/365/390 family Caddy engine.

I'm combining two project ideas into one and going big block (hopefully) on the '58.  The motor I have is a 472/500 family block.

Quoting: EDGE

Hi

Comments on the Manifold please, Mr Edge.

Found this interesting site last night . . .

http://www.hogansracingmanifolds.com/index.aspx

[Jamieg285]

Random idea, no idea if it's feasible, but could you make some sort of adapter to fit the tri-carb setup to the big block?

I'm sure that with less than 5 mins thought you could work out if it's a good or totally stupid idea.

[FUBAR]

Aah ok, didn't realise it was for a diff sized block, shame because that looked cool.

[Roadkill]

Quoting: Jamieg285

Random idea, no idea if it's feasible, but could you make some sort of adapter to fit the tri-carb setup to the big block

Anything's possible but I think that could end up being even more costly and time consuming.



Apparently the sketch I've shown above is an "Isolated Runner Manifold".

"The Isolated Runner manifold is not standard equipment on any domestic V8, but common on earlier high- performance 4, 6, 8 and 12 cylinder imports and racing Cobras (289 & 427), typically using dual-throat Weber, Dell’Orto, Solex or Mikuni PHH carburetors. These are not true manifolds, as their only function is to connect 1 intake port to 1 throttle disc or slide. There is no commonality or sharing (except for a vacuum balance hose or passage for idle quality).
IR manifolds, where each cylinder can only draw from one barrel, offer the absolute best idle quality, throttle response, tolerance of high-overlap cams timing, and allow accurate tuning of intake length for maximum torque. The disadvantages are higher mechanical complexity, synchronization problems, limited under-hood space for intake stacks, and much higher manufacturing costs.

Larger motors will develop less power than with conventional tunnel-ram set-ups, due to inadequate flow capacity - each cylinder only “sees” 1 throat or barrel. There is no carburetor currently available large enough for 1 barrel to supply enough air for a 70” cylinder.

Most port fuel injection, such as traditional Hilborn, Enderle, Lucas, etc. “stack” injectors are isolated runner types. Stack fuel injection does not have the same maximum engine size limitation, as each throttle can be as large as 2.90” diameter! This is only possible with injection, as the low vacuum would produce inadequate signals for accurate carburetion."

http://www.strokerengine.com/IntakeManifolds.html