ZR8ED

I'm still on the hunt for a n/a intake, but I went ahead on the work on the turbo manifold while I wait. Hopefully I will find another intake soon.

I matched the throttle body to the intake, and then polished pre throttle plate and post throttle plate. It is pretty rough from the factory. I removed the rough casting marks as far into the intake runners as I could reach (approx 3 inches.) some of the casting marks intrude into the runner tubes more than 1mm. I'm now looking for someone to extrude/hone the manifold, to smooth out further in. That may take some time, and I want to take the n/a manifold as well and have them both done at the same time. With another tool, I may be able to reach a bit further, but I will do the best I can with what I have until I can determine another option.

It was a very productive weekend working in the garage on this stuff. I've had a few "resources" stop by to guide my work and make suggestions on how to proceed with the cyl head work as well.

V2Rocket

what people do sometimes with the 951 mani is cutting the plenum down the middle, polishing all the runners and then welding the cutout back on lol

blown 944

One other idea I got from Dave McGrath with CEP is to cut a slot a few inches behind the tb and weld in an air diverted to equalize flow to the #4 cylinder. I have done this on mine and with the same tune the egts dropped about 75degrees on that cylinder. I dont have a 4 channel to measure consistency across cylinders but I can't see it hurting. Something to think about during your testing.

ZR8ED

I've seen that done before, but its beyond my current equipment and ability. Not to mention totally not worth the effort unless I was trying to build some crazy motor.
I'm still not sure I will use this manifold at all. I won't decide until I see the n/a manifold up close. I may end up trying them both. Maybe I'll test the turbo manifold first, and use my own manifold, If I don't like the new one.

Blown 44: Thanks for the tip, but I don't think it is worth the effort as this is only for my n/a.

Paulyy

Sid, You have any pictures of that?

ZR8ED

I've been doing some more searching for info that I had hoped would be already available, and so far I have not been able to find any concrete source that can tell me the volume of the plenums on each manifold. I can obviously measure the turbo manifold, since I have one sitting on the bench, but has anyone accurately measured the plenum volume of an n/a? Anything less than 100% of the displacement of the engine is not ideal. It seems 150% is a typical goal for a performance engine.

V2Rocket

if you can wait a few days, i have a NA intake mani that i cut apart to re-use the runners and i could measure it or just send it to you. plenum didnt get touched

ZR8ED

Measuring the plenum would be awsome! I'm in no rush. Finding a manifold is proving to be a bit more difficult than planned.

Ok onward and upward. Here are a couple of pics illustrating the roughness inside the runners. Yes some roughness is required to promote smoother airflow (lots of info on this out there) BUT it does not have to be 5 o'clock shadow kind of rough! The first pic is of a runner with the roughest casting mark 75% removed. This mark is throughout the entire manifold and is approx 1mm thick. The second photo is of the first major pass of the die grinder. There is still plenty of sanding to do, and I am going to match the cyl head and intake runner to the gasket (not the old gasket in the picture) to make the smoothest transition possible. I'm not out to "hog" the head, the ports or the manifold. Just clean it up, smooth, and port match, and remove any obvious obstructions. I will get more detailed with the head. All the runners look like the last picture as of tonight.

V2Rocket

i may run to the junkyard this week, there is a 924S there i could snag the mani off of for you if you really want. otherwise ill have to dig out my cut-up one.

333pg333

I assume Sid is talking about this.

btw, why would you want to put a turbo intake on an n/a? The intake is crucial on an n/a where on a turbo...not so much. For high performance turbo motors the intake is substandard but for most cars in here it is sufficient. It was never designed for a high output motor. Not sure that you'd sacrifice equal length runners on an n/a though.

ZR8ED

Cool pic patrick! I stumbled upon the turbo manifold before I found an n/a one, so I've just gone ahead and started working on it, Once I find a non turbo manifold, I will do the same thing to it. It is looking more and more like I will sell off the turbo manifold once complete. The head I MAY keep for one day if I need it, as it will be a huge improvement over the stock head. I have no intention of taking apart my running car to swap a head so late in the driving season. I want to drive it as much as I can until winter.

I posted an ad for a manifold on Kijiji.ca to help my search.

As a side note, you should see the pile of aluminum fillings that has come from the intake! Its a heck of a way to shed weight! I have removed approx 1mm off the walls. I am working on getting some better tools to reach all the way into the intake so I don't have to mess with extrude honing. Through the main throttle body port, I was able to reach 75% of the way in last night, so it is coming along very nicely! I'll get to that last part. There are some cool micro tools out there!

North Coast Cab

Been there done this.
Going from memory since the data is at home. The turbo runners are almost the same diameter and length as the NA. The NA plenum is bigger which helps feed the motor at higher RPM's. Swapping them made very little performance difference, as measured on a Dynojet.
Plenum size, runner diameter, and runner length all control the peak HP and Tq points, but do not necessarily raise the peaks.
I made a custom short runner, large plenum NA intake and it moved the Hp and Tq peaks up about 4-500RPM's which was desirable. It was not huge but every little bit counts when raicng. If this is for a street/track application it is not worth the effort. That was with a straight through "ram air" type filter set-up.
Speedforce Racing has some really nice custom intakes if you want to pick-up an off the shelf model too. the barn door is still the weak link so if you can MAF around that it may increase the performance.

Amber Gramps

Oh, Spencer..... Are you sure it was a 24S and not 44S.

No, it has to have been a 924S. I do remember that it had 4 bolt hubs soooo close.

V2Rocket

24S would have had 5-bolt hubs. 24 has 4-bolt.

Amber Gramps

I'm so confused.

You are gonna make me go back over there, aren't you?