Has anyone measured the differences in the flow characteristics of the turbo intake manifold versus the n/a intake? I searched through pages of pictures, but no side by side comparisons.

I'm pretty sure that it will "bolt" to the head, but that it will require fabrication to work with the afm and throttle body (are the tb's the same size?). It sure looks like it would have less bends, thus a more direct path for atmosphere to get pulled into the engine.

I have never seen the two manifolds compared together, and I'm deciding which one I should get as a spare for me to modify for improved n/a breathing. I don't want to break out the die grinder to an n/a manifold just to make it as good as a turbo one if the turbo manifold is already better. I'm interested in runner lengths and diameters, and throttle body diameters primarily.

Spare me the "its not worth it to mod an n/a" This is a "just for fun/the little engine that could" kind of project.

Cheers.

 

tb's are not the same bolt pattern. the 951 one is rectangular. 944na is square. u'll also need a new (prob custom) throttle cable.


i've thrown the idea around. but routing the AFM + TB + filter and not hitting the fenderwell is an issue.

 

bolts right on- you can use a turbo throttle cable... but would need some kind of tube to go from the tb to the afm. Nine-44 has all these parts and is planning on doing this to his n/a but it looks to me like it would be about the same lengths, you may loose alittle bottom end.

 

i believe in terms of actual airflow the stock 951 mani is a chunk of **** compared to an NA mani for an NA application

 

Interesting. Other than it being designed for turbo use, and likely packaging issues (underhood room) why do you believe this? Are the runner diameters significantly different, or is it just the general shape of the tubes?

I'm hoping I can at least find one to look at side by side and take some measurements. An n/a should be easier to find than the turbo one.

Anyone near Toronto with both that I could have a look at?

Cheers!

 

The shape of the tubes. You want as few bends as possible, wiht the largest radii as possible (2*ID or greater is ideal), S bends are a big no-no, and if you have to do it, you need a straigth length 4 times the inner diameter of the runner. And last but not least, you want your runners to be as symmetrical as possible.

 

Thanks for the info!
I still would like to see one side by side for comparisons. It's pretty hard to see just from pictures, but it looks like I'm off to find a spare N/A manifold.

A part of me would love to go wild with some Webers or better yet ITB's, but I've been there and done that before. Too easy to get crazy expensive. Modding a stock part = free.

 

i can take some side by side pics when i get home tonite.

 

Ok. So I found a turbo manifold before I could find a n/a one..go figure. I am going to pick it up anyways to have a look. If I don't like it, I'm going to mod it anyways, clean it, coat it, and will sell it to a turbo guy. It will be a learning experience. I will of course respond to this post with some results.

 

Success! I got a bit carried away though.

The guy I visited today has a wild ls6 powered 944. He was selling off some turbo parts, so I snatched a cyl head/cam, the turbo intake and throttle body, and scored a front strut bar.

Before I get ahead of myself, I have a question. Is a turbo cyl head the same as an NA head? I also got a spare junk head so I can experiment with it.

I started to measure the ports on the intake and cyl head, and I found right away that the intake manifold has a slightly larger diameter than the head. Approx 1mm average diameter. Both the head and intake had passageways that were quite rough and had even rougher casting marks. I don't want to turn this into a cyl head thread, So I will start one just for that. I see increased flow potential. Once I determine if I can use the turbo head on my n/a, I'll get it checked out, and I will be able to begin some p&p work and port matching.

I still need an n/a intake so I can compare for myself, but this will be a part time project so I'm in no hurry.

Now back to the turbo intake manifold.
Lots of internal roughness and casting marks. I also saw that the throttle body appears to be 1mm step down where it mates to the manifold. (The manifold is at least 1-2mm in inside diameter LARGER than the inside diameter of the throttle body behind the throttle plate.

Like I said already. I am going to source an n/a manifold so I can compare it for n/a use. I will likely mod the turbo manifold and port match the throttle body and then sell it.

I'm off to find a manifold, and restock my supply of die grinding tools.

 

It wouldn't be to hard to make a manifold to carry some motorcycle carburators as independant throttle bodies. Figuring out the right size, linkage and tuning could be a real pain.

 

Below are pics of the stock 944 and 951 intake in the same car. A friend of mine converted his stock intake manifold to a 951 one with a K&N air intake. It significantly opened up the engine bay. I am planning to do the same conversion this winter. With the straighter runners on the 951 intake manifold and the K&N air intake filter set up it appears that the path for the air is more direct. My friend's car feel much more alive in the high rpms comparing to mine with the 951 intake manifold.

 

Thanks for the pics! Hey that strut bar in the second photo looks just like my new one! I was wondering which way it bolted on.

Is the TPS the same turbo to n/a? or did he need to switch it?

 

the turbo head will work- it has more desireable exhaust valves and springs- the exh. ports are ceramic lined so normally when they start flaking they are junk because the ceramic gets into the turbo- but for n/a it just goes out the exh-or into your converter. Most people w/ turbos that want to port the head use an n/a head and have it ceramic coated in the ports.

 

those looooong runners and the big plenum on the NA manifold are for torque...which the 944 desperately needs as much of as it can get. let us know how the swap works out.