New Acquisition: dohc turbo

Shaun41178(2) · Post by **Shaun41178(2)** » Sat Sep 13, 2008 4:21 pm

fabbing up the external wastegate dump.

http://www.shaun.saturnet.net/pics/dohc/100_1526.JPG

http://www.shaun.saturnet.net/pics/dohc/100_1527.JPG

http://www.shaun.saturnet.net/pics/dohc/100_1529.JPG

http://www.shaun.saturnet.net/pics/dohc/100_1528.JPG

Aaron · Post by **Aaron** » Sat Sep 13, 2008 7:19 pm

Shaun41178(2) wrote:http://www.shaun.saturnet.net/pics/dohc/100_1525.JPG

So I am guessing that these are routed wrong then. The one you say is supposed to go to the intake is actually going to the catch can.

I looked pretty closely at it, and I'm pretty sure that that nipple is for the IAC, in which case, the way it's routed, would fuck with the idle. Just pull the line off, leave the nipple open, and see if that helps.

Billybo455 · Post by **Billybo455** » Sat Sep 13, 2008 7:20 pm

we need to teach you how to weld!!!

Aaron · Post by **Aaron** » Sat Sep 13, 2008 7:25 pm

WG looks good Shaun!

As for the welds, it looks like that pipe is the generic exhaust pipe you buy from like an auto parts store. If so, it has this shitty coating that makes welding to it very difficult. I had this problem on my Maroon DOHC car. But the welds are fine, function before form.

Billybo455 · Post by **Billybo455** » Sat Sep 13, 2008 10:03 pm

a simple wire wheel cleans the surface pretty well before you weld. i guess form over function, but your welds look like you are welding a little cold. up your heat range just a fuzz and give it another go. either that or you are welding away from your heat source. always make sure to weld which ever way the torch or wire is feeding.

Shaun41178(2) · Post by **Shaun41178(2)** » Sat Sep 13, 2008 11:48 pm

wastegate pipe isn't welded yet. I just cut it for fitment today. I don't have a welder. The crossover looks to me like a gassless mig was used on it originally so the welds are pretty bad looking. They don't leak but look bad. Where there were pinholes I ground down those welds and had them tigged. Not sure if those show up well in the pics or not.

All the future welds will be tigged

Pulled the trunk side exhaust manifold, didn't have to do much gasket matching on them. Just a smidge at the ports needed to be taken off. Ground all the rust off, and painted with 2k degree vht header paint. Its curing in the oven now. I did this just to keep the rust from forming on them since you can't really see the exhaust manifolds all that well. So aesthetics wasn't on my mind for this.

Sent the old turbo exh housing back on fri as I got the wrong size so they will correct that and hopefully I will have that back by the end of next week, by then I should have the crossover pipe done, painted and heat wrapped.

fieromadman · Post by **fieromadman** » Sun Sep 14, 2008 9:05 am

Aaron is wrong about the t-body. None of those vaccue lines have ANYTHING to do with the IACV. Yeah... thats all I have to say about that. Mine were all blocked off with no problems.

Aaron · Post by **Aaron** » Sun Sep 14, 2008 1:26 pm

fieromadman wrote:Aaron is wrong about the t-body. None of those vaccue lines have ANYTHING to do with the IACV. Yeah... thats all I have to say about that. Mine were all blocked off with no problems.

I may be. But I have it right in front of me, and I am examining it closely.

The port before the throttle body is not inline with the TB, it is perfectly inline with the vacuum port on the left side (The one blocked off on Shaun's engine). And when I blew into that vacuum port, I felt the pressure ont he port before the plate (The only port before the plate). Once I blocked the port off with my finger, I could not blow into the nipple. So unless the port before the plate feeds both the valve cover breather and IAC, there's no other way.

I could very well be wrong, but I don't think so. Is it that hard to have Shaun just pull off that vacuum line, see if it makes a difference? If the car jumps up to a 2000rpm idle, then we know it's just a vac port. If the car idles normal, then we know it is the IAC port. Like I said, it doesn't make sense that GM would do it that way, frankly it'd be a retarded setup, but looking at the TB, that's how it appeared to work.

Shaun41178(2) · Post by **Shaun41178(2)** » Sun Sep 14, 2008 1:30 pm

doesn't anyone have a vacuum diagram from a 97 lumina or something?

Aaron · Post by **Aaron** » Sun Sep 14, 2008 1:32 pm

Just start the car and disconnect the damn vacuum line.

Shaun41178(2) · Post by **Shaun41178(2)** » Sun Sep 14, 2008 1:54 pm

in case you haven't been paying attention, I have the crossover and turbo off the car not to mention the exhaust manifolds.

Aaron · Post by **Aaron** » Sun Sep 14, 2008 2:01 pm

That's right. If I get around to it, I'll pull off the IAC today and look inside.

Aaron · Post by **Aaron** » Sun Sep 14, 2008 2:14 pm

fieromadman wrote:Aaron is wrong about the t-body. None of those vaccue lines have ANYTHING to do with the IACV. Yeah... thats all I have to say about that. Mine were all blocked off with no problems.

No, you're wrong.

I just went down and checked the TB. I pulled it off the intake arm, and pulled the IAC off.

The casted port before the throttle plate goes to, and only to, the nipple on the far left, as a vacuum source for the breather line. It is the only port before the throttle plate, and it only goes to that nipple. With the IAC removed, I blew into the nipple, while plugging the port before the plate with my finger. I could not blow through it, it was sealed.

The very top nipple, pointing to the trunk, like I said, is the feed for the IAC. With the IAC removed, and my fingers plugging the IAC outlet on the backside of the TB, and my fingers plugging the IAC port, I could not blow through the top nipple, it was sealed. Thus it is not a vacuum nipple. It is the inlet for the IAC valve, and should have a hose to the intake (Or can be left open to get unfiltered air).

So Shaun, the line going to the catch can needs to instead go to the intake. Then run a line from the catch can, to the nipple that was blocked off on your TB (The left side one for the breather line).

Shaun41178(2) · Post by **Shaun41178(2)** » Sun Sep 14, 2008 2:40 pm

are the intake gaskets reusable? Mainly the lower to the upper intake gasket.

Aaron · Post by **Aaron** » Mon Sep 15, 2008 2:38 am

Technically, no. However, I've reused them plenty of times without any problems. So make sure it is in good shape, and the plenum is torqued well, and it'll be fine. By well, I don't mean a lot, as they strip even when torqueing to the factory specs. But evenly.

p8ntman442 · Post by **p8ntman442** » Mon Sep 15, 2008 6:27 am

yeah, I have reused them as well with no issues

Kohburn · Post by **Kohburn** » Mon Sep 15, 2008 8:30 am

that line off the back of the IAC cavity is not needed on this setup. I can't access my photobucket from work, but if i remember right the IAC feed through the hole infront of the throttle plate, into the vaccuum well behind the plate. the same vacuum well that the breather and vac lines are hooked into.

I'll double check when i get home if i remember.

fieromadman · Post by **fieromadman** » Mon Sep 15, 2008 11:02 am

God I hate prooving people on the internet wrong...

Here's pictures to show you why your wrong:

Start off with a basic Diagram. This shows that none of the Vac lines are for "IAC feed."

Here is a shot to show you what is what.

Here is a side shot through the IAC of the same things, just a different view

Another view of the same damn thing.

Here is a side view to sho that the vaccume line has nothing to do with the IAC passage so you can see the hole going from one passageway to the other.

And in case you guys are wondering where the other two vaccue ports on the t-body lead to (they are just going into the manifold passage after the IAC plunger):

Now, who's the bitch?

Aaron · Post by **Aaron** » Mon Sep 15, 2008 11:50 am

Dude, I fucking took apart the throttle body.

That top vacuum line IS NOT a vacuum port. Breathe into it. I did. It did not put air into the manifold. It put air into the IAC outlet. Cover the IAC outlet, and the IAC bore, and it seals, you can't blow into it.

The nipple on the left for the breather, is direct, for the only port before the plate. That port goes to, AND ONLY TO, the breather nipple.

p8ntman442 · Post by **p8ntman442** » Mon Sep 15, 2008 12:36 pm

I know on the quad 4 the IAC gets air through the large nipple attached to the breather box.