Improved Iron Head Intake

[1QUICKHATCH]

The lx5 TB (3.5l dohc found in the olds intrigue ) uses the same iac, tps connectors as a 3.4 iron head tb from what I can remember. You are going custom anyway so I would not worry about throttle cable placement too much. You can look into the late 90's 4.3 tb, or a LS throttle body from a truck but you don't need that much air with iron heads.

Years ago people on here used F*rd tbs for upgrades!

[34blazer]

Yeah I was thinking in the future chopping up a lower all the way up to the valve covers and starting from there.


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Could do that, and the injector placement is already there too.

[ericjon262]

you could also make an ITB setup that bolts to the lower...

[camaroyoungster]

About that ITB plenum that eric was talking about. Just drew up some Basic images of what it could look like. Might be angled up a little more to clear the valve covers but same basic idea. Sadly enough no one really make ITB's in three's so I sought to find a solution. Here is what I found. Polaris has the 650 triple and would be just 5mm off which is fine because they mount to rubber boots and the way I made all the runners the exact length to make sure that they run fine. Now in the drawing, thats not how the throttle bodies will be mounted, just didn't have enough time to draw the boots and stuff on CAD. I also didn't want to just leave you with a blank manifold.

1.Now if I go this route which sounds like it could be pretty awesome or painful ill need to figure out mechanisms to get both sets to open and close. I also have to figure out a throttle position sensor too. The polaris TB's have a 3 wire sensor like the 3.1's and 2.8's but I am not exactly sure if they run from 0-5 volts and I have been digging around to find out but not much.

2. I really dont know much about ITB's like idle control or how to hook up speed density or MAF. I was thinking that maybe if I went with speed density I could use the cold start injector bung because that is all plumed to each runner which would also help equalize pressure unless I am wrong on that. The throttle bodies also have vaccuum lines that I could possibly tie into their.

3. Right now I am currently waiting for my dad's friend from work to get some bases flanges back to me so I can start ordering tubing and get going on this project. He is cutting them out with a CNC plasma cutter which is real cool and stuff

[Superdave]

ITB's are fun but don't expect to daily drive it... ask me how I know

[camaroyoungster]

Could you possibly tune it to run well on the street though?


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[robertisaar]

i don't think it is going to be an issue of tuning so much as it's going to be...... finicky when not driven full tilt. you could probably sabotage parts of the main spark map to make throttle transitions less jumpy, but that's kind of the point of ITBs, super responsiveness(and how they effect the powerband).

if you had something neat like DBW ITBs that you could adjust throttle pedal sensitivity to suit conditions, that would be interesting. I believe BMW started doing that in the mid-late 90s for their M engines.

[1988GTU]

didnt the SHO have something of the sort? Six ITB's and one main TB?

[ericjon262]

you could also use an eccentric throttle.

[camaroyoungster]

How would responsiveness change with like a turbo to have some lag added to it?


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[ericjon262]

How would responsiveness change with like a turbo to have some lag added to it?


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turbo lag refers to boost pressure, not really the engine's response.

[Guest]

About that ITB plenum that eric was talking about. Just drew up some Basic images of what it could look like. Might be angled up a little more to clear the valve covers but same basic idea. Sadly enough no one really make ITB's in three's so I sought to find a solution. Here is what I found. Polaris has the 650 triple and would be just 5mm off which is fine because they mount to rubber boots and the way I made all the runners the exact length to make sure that they run fine. Now in the drawing, thats not how the throttle bodies will be mounted, just didn't have enough time to draw the boots and stuff on CAD. I also didn't want to just leave you with a blank manifold.

1.Now if I go this route which sounds like it could be pretty awesome or painful ill need to figure out mechanisms to get both sets to open and close. I also have to figure out a throttle position sensor too. The polaris TB's have a 3 wire sensor like the 3.1's and 2.8's but I am not exactly sure if they run from 0-5 volts and I have been digging around to find out but not much.

2. I really dont know much about ITB's like idle control or how to hook up speed density or MAF. I was thinking that maybe if I went with speed density I could use the cold start injector bung because that is all plumed to each runner which would also help equalize pressure unless I am wrong on that. The throttle bodies also have vaccuum lines that I could possibly tie into their.

3. Right now I am currently waiting for my dad's friend from work to get some bases flanges back to me so I can start ordering tubing and get going on this project. He is cutting them out with a CNC plasma cutter which is real cool and stuff

Buying a Ryan Falconer ITB setup from a member on here will be cheaper than building your own.

[ericjon262]

Buying a Ryan Falconer ITB setup from a member on here will be cheaper than building your own.

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I don't think that was the point though, the OP has said he wants to do this as a learning project.

[Superdave]

Could you possibly tune it to run well on the street though?


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With a mild cam sure, you could probably get it to be decent on the street sometimes. Like Robert said, it's finicky. Some days mine would be great and others it would do random weird stuff.

If you could get a bin file that had a really huge VE table and maybe with a ton of work it would do ok. The instant throttle response was really nice but even I threw in the towel and went back to a 3500 UIM with a 75mm LS1 throttle body. I saw no change in trap times at the track so there really wasn't much if any power difference between the 2.


Here was mine: http://www.sdsgarage.com/Misc/Camaro...e/SDC12674.JPG



I still think that making something like the attached pic is your best bet.