My NEW fiero turbo setup

[Shaun41178(2)]

If you block the throttles, can your idle air system control the idle?

I am finding out that no it can not. I am not sure of this as I am not setting an iac code at all. I haven't pulled the iac out either to see if its moving. I do have vacuum like the brake booster and the map, running off of the iac distribution block, I am not sure if this is affecting anything or not.

When I pull the 3/8th rubber line off of the iac, one would think the idle would kick way up because there is a large vacuum leak. I am finding this not to be the case. The idle barely changes if at all.

Here is the routing. its the remote iac, to a 3/8ths line, to a small distribution block. I have 1 port on the block going to the brake booster, one to the map sensor, then 2 are coming out that are feeding the two banks. So essentially one line out of the distribution block feeds the trunk side, and one feeds the firewall side. They are T'd off to feed the 3 cylinders on each side. I am using 3/16th line to feed each cylinder. I don't think this is too small however, I would imagine the iac can open enough to keep the thing running.

Maybe the distribution block is the choke point? Not sure.

[ericjon262]

what are you using for air lines? maybe collapsing?

[Shaun41178(2)]

I got a reinforced 3/16 fuel line because I thought this might happen. Pretty sure they aren't collapsing, I just think they are too small to feed the air this motor needs to each cylinder when each blade is blocked off.

There is about a 2-3 second delay from the time I uncap the main feedline to the distribution block, to the time the idle goes up. I can feel the vacuum on the main line but its not that strong which my vacuum gauge confirms. Its only around 10in vacuum max and it fluctuates between 0-10.

I should prob get a distribution block, and run each individual line to it, instead of combining cylinders.

Blocking all the runners with a plastic bag will kill the engine. The iac might be able to adapt fast enough, but the air has to travel too far, or the small lines just can't feed enough

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[ericjon262]

I plan to use aluminum fuel line for all of my vacuum and boost lines so that I don't have to worry about collapsing or bursting.

[The Dark Side of Will]

I should prob get a distribution block, and run each individual line to it, instead of combining cylinders.

That should be step 1. A 3/16 line *might* supply enough air for one cyinder, but three cylinders T'd into one 3/16 line is probably too much.

There is about a 2-3 second delay from the time I uncap the main feedline to the distribution block, to the time the idle goes up. I can feel the vacuum on the main line but its not that strong which my vacuum gauge confirms. Its only around 10in vacuum max and it fluctuates between 0-10.

I just think they are too small to feed the air this motor needs to each cylinder when each blade is blocked off.

Sounds like it. You may need to go up 1-2 sizes with the hose and have one feeding each cylinder.

Blocking all the runners with a plastic bag will kill the engine. The iac might be able to adapt fast enough, but the air has to travel too far, or the small lines just can't feed enough

If you open the IAC line completely, does the engine still die when you block the stacks?

[Shaun41178(2)]

If you open the IAC line completely, does the engine still die when you block the stacks?

Yes. Because the idle drops so quick. if I have the iac main feed wide open to the vacuum block, and I block off 5 cylinders with plastic bags, it will stay running. It idles at like 900rpm or so, so as soon as I block the last one, the one that leaks the most through the blade, the engine rpms drops too quickly, and the engine dies.

Once again I believe this is due to each bank of cylinders, being fed off one 3/16 line, which is then split. I think that single line just isn't enough. I have ordered a new vacuum block designed for 6 ports so each runner can have its own iac source.

I also remeasured the tb blades and they are 50mm if not a shade under. Crazy, each cylinder has nearly as large a tb as a stock 2.8 tb feeding the whole motor.

[The Dark Side of Will]

Yes. Because the idle drops so quick. if I have the iac main feed wide open to the vacuum block, and I block off 5 cylinders with plastic bags, it will stay running. It idles at like 900rpm or so, so as soon as I block the last one, the one that leaks the most through the blade, the engine rpms drops too quickly, and the engine dies.

How quickly the RPM drops isn't relevant... it just isn't getting enough air.
The rate of RPM drop is important when the IAC is in the loop, because it has to open wide enough fast enough to give the engine enough air to stay running. When the IAC is removed and the IAC port is wide open, that's not a factor.

Be ready to go bigger on the hoses in case 3/16 per cylinder isn't big enough.

The engine's firing order is 1-2-3-4-5-6, so in each bank, the cylinders fire 240 degrees apart. What's your intake duration? 260? The cylinders are probably only overlapping for a very short period of time, so I no longer think it's because the lines are T'd together... they'd just not big enough. You could run 3 vacuum lines with 1/4, 2/5 and 3/6 paired. That would completely eliminate the overlap period, yet not go all the way to 6 connections.

Now there could be some burglary by each cylinder of the one next in line, but the period of overlap of the intake valve events isn't very much, so I would expect that to be pretty minimal.

[Shaun41178(2)]

Cam specs:

280.6/283.8 duration seat to seat
225/227.6 duration .050"
.565/.526" lift
111 ICL
111 LSA

Lift is with 1.5 rockers

I ordered a dist block with more ports and more volume so we will see if that fixes the issue.

[The Dark Side of Will]

Lou Dias over on Pfiffle has been quoting this document for ever regarding how awesomezors the iron heads are: http://www.gafiero.org/docs/60V6Pwr.pdf

I hadn't looked at it until now. Check out figure 3. Look familiar?

[Shaun41178(2)]

I have studied that pic as I have the same book in paperback form. It appears fig 3 is a different intake entirely then from what we have. Its close but either what we have was modified by gm, or its different altogethor.

[Shaun41178(2)]

Got this in. This should help out.

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Oh and fyi, in case anyone was wondering, you can run the iac valve on the same lines as the vacuum ports but I would not recommend it. At idle, it will screw with things as of course the iac does create a vacuum leak when its open.

So since I don't have any extra places tapped to run lines for idle control, I am going to try to adjust it by slightly having the butterflys open at idle. its either that, or pull the whole intake off and modify it further for those.

[The Dark Side of Will]

I have studied that pic as I have the same book in paperback form. It appears fig 3 is a different intake entirely then from what we have. Its close but either what we have was modified by gm, or its different altogethor.

What do you see that's different?
I haven't looked at mine in a while since it's been at ALLTRBO's place.

Cool new toy.

[Shaun41178(2)]

The entry ports on the intake are round and have what look like silicone couplers on them. They way the intake is shaped, there is no way to put couplers on it in those locations unless the runners have been modified. Thats what it looks like to me anyways.

Sell me one of your butterflys from your intake One of mine is warped a bit and won't seal right.

[The Dark Side of Will]

Sell me one of your butterflys from your intake One of mine is warped a bit and won't seal right.

I think this is a better idea:

The GM TBI throttle bores from the 305/350 trucks are 1.68" = 42.7mm. Might be able to hone them for a tight fit.

Should be able to find 6 of those pretty easily. I can help with the machine work to install, if needed.

You may need to go to 3/8 or bigger lines to have enough air for the engine to idle.
BMW uses close to 3/4" interconnects on the S62, but that is a production engine that doesn't have much valve overlap.

[Shaun41178(2)]

I remeasured and the blades are just under 50mm so those other ones are way too small

1.964 in to be exact

[The Dark Side of Will]

Ahh... That's pretty darn big for a single cylinder. I'm sure there's something OE on the market at that diameter which would be cheap and easy to get.

Googled "50mm throttle plate": http://dodgeforum.com/forum/2nd-gen-ram ... y-mod.html

[Shaun41178(2)]

50mm is still just a tad bit too big. I would have to sand it down, which i would prob lose the bevel on the edge to allow it to seal tight. Might be worth a shot though if trying to fix what I have doesn't work.

[The Dark Side of Will]

I was thinking that you could get high quality throttle blades, use them as-is and have a machine shop bore the stacks precisely to match the throttle blades. There would be a slight edge at the bottom of the bore, but you could blend that with a flapper wheel easily enough.

[The Dark Side of Will]

How's this coming?

Ninja Edit: I hadn't seen your May '13 edits on your first post

[Shaun41178(2)]

Butterflys appear to be sealing much better now. Before you could see a slight gap between the bores and the butterflys on all 3 trunk side cylinders. I used a light under each blade and made adjustments until nearly no light could be seen.

Pouring water down into the bores now, they hold the water instead of just leaking out.

I am working on finding a better way to seal the brass injector bungs to the braided lines as i am Leary on trusting them to not leak with the fuel pressures i plan to run. Once the plenum goes on seeing leaks will be near impossible so i want to make sure i don't have to do it again.

Don't have any pics to show.