engine and drivetrain intake manifold issues

[nbristow01]

I was looking at my intake, factory one, and realized that it is not really designed well. Like you will see on many engines the plenums, runs, are equal length. On the 02 mainfold the inner two are substantially shorter than the outer 2. As we all know, the more identical we can get each cylinder to operate, ie temp, mass(balance) etc the more hp and better overall operation. The inner 2 on a stock manifold look to get a more dense mixture and the outer 2 a bit leaner.

i thought about making a new manifold then i saw what i think is called a megasquirt manifold? All runs the same length etc. It looked almost identical to the manifold I was drawing up. It is for injection and can very easily have a carb mount welded on, vacuum lines added etc.

before I reinvent the wheel, has anyone ever tried this?

[slash02]

Not that I am aware of.

You would have to weld up the injector bungs, put a plate on the bottom in place of the throttle body, and the carb would probably have to be a sidedraft, that intake sits pretty high up compared to the 2002 one..

Anything's possible.

I was looking at my intake, factory one, and realized that it is not really designed well. Like you will see on many engines the plenums, runs, are equal length. On the 02 mainfold the inner two are substantially shorter than the outer 2. As we all know, the more identical we can get each cylinder to operate, ie temp, mass(balance) etc the more hp and better overall operation. The inner 2 on a stock manifold look to get a more dense mixture and the outer 2 a bit leaner.

i thought about making a new manifold then i saw what i think is called a megasquirt manifold? All runs the same length etc. It looked almost identical to the manifold I was drawing up. It is for injection and can very easily have a carb mount welded on, vacuum lines added etc.

before I reinvent the wheel, has anyone ever tried this?

[nbristow01]

It looks like the perfect basis for building a manifold. The hard part of getting the pipes matched is done. Just basic stuff. I may give it a whirl.

Once I get this engine built and running in a car. Will be a very fun experiment

Thanks for the picture by the way.

[mossyboy6]

If you spengine any time and effort, might as well go to dual sidedraft or dual downs.

[nbristow01]

I'm trying to make this engine a very streetable one so i am steering clear of duals. I love how they look and perform when set right but keeping them synched and being in stop and go traffic makes them get nfum quickly for me

[eurotrash]

What about an adaptor plate for a Tii manifold to accept a single side draft?! At least we know it fits under the hood and its horozontal..?!

Or crazier yet, slice that 318 piece off about 2 inches in, roll the thing over and weld it back together. Then massage the TB side to accept a 32/36 or better..?? This seems doable and the design isn't too far off, plenum-wise, from the 2bbl manifold..?? Clearance could be an issue I suppose..

[aa/fd]

I think you have the right idea, this manifold like the Tii has a significant equal runner length (longer), which in my mind equals a way better power curve. Adapting a carburetor to it and closing the hood might be a issue. The obvious choice would be a down draft Weber, Holley etc, a lot would depend on the plenum area beneath the logo. It might be wise just to go the megasquirt or 318i Bosch route just because it puts you closer to this century on engine control systems and would just run better. There is a good article in the FAQ engine section on the 318i system adaptation which this manifold is used.

[BillWilliams]

I am not a carb guy, but wasn't there a Linyx manifold made a few years back that did or try to do this?

[eurotrash]

I am not a carb guy, but wasn't there a Linyx manifold made a few years back that did or try to do this?

Yes sir.. And I heard it works well. But this sure is a fun conversation..

[bluedevils]

The 318i manifold as shown above has equal length runners, just check the bottom of the manifold. Don't know about carb manifolds, but they are probably as close as possible to equal length, I am sure BMW knew what they were doing when they built these engines.

[nbristow01]

Well first step is getting this engine built then finding a car to put it in, after that I am going to go for it and do the megasquirt to carb manifold endeavor.

I know fuel injection is current but one of the reasons I want an older BMW is because the pleasure I derive from modifying it, no smog, no electronics, just me and the car. I have enough electronic in my life with my Audi A3 and Mercedes C350.....get this, I had to take the Mercedes in for a software download...what the!!!!!

man I grew up on Jags and MGs with Solex and Webers. I just like the simplicity of it I guess....jeeez, a freakin software update?? Man thats just wrong haha

[bluedevils]

I feel your pain and agree on the simplicity of carbs. Come to think of it, carbed cars are the cars for the 21st century, you can fix them with a set of screw driver and pliers, on the fly.I wish I knew more about them. Time to take the Solex apart to learn.

[Guest Anonymous]

I know fuel injection is current but one of the reasons I want an older BMW is because the pleasure I derive from modifying it, no smog, no electronics, just me and the car. I have enough electronic in my life with my Audi A3 and Mercedes C350.....get this, I had to take the Mercedes in for a software download...what the!!!!!

man I grew up on Jags and MGs with Solex and Webers. I just like the simplicity of it I guess....jeeez, a freakin software update?? Man thats just wrong haha

Which Jags?

[Preyupy]

One of the problems you will have modifying the E30 318i or Tii manifolds to use a carburetor will be they were never designed to flow air AND fuel through the plenum and runners (other than the fuel from the cold start injectors on start up only). I believe the plenum on both manifolds are so big that the velocity of the air/fuel mixture will slow down so much that the fuel will baiscly fall out of the air. They will both be horrible when they are cold as the fuel will condense inside the manifold and you will have to run horribly rich to just get it to run at all. At wide open throttle with the engine fully warm I suspect you might make a bit more power than the stock 2bbl manifold with the same carburetor but I will bet the low end torque and fuel mileage will suffer a lot. This is why the V8 guys run a single plenum intake with a spacer on race engines that don't run worth a damn below 3000 rpm and the ones that run really well on the street run a dual plenum to keep the low RPM air/fuel velocity up so they run below 3000 rpm.

[eurotrash]

I once joked about rolling that e30 manifold over and bolting on a carb..