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Discussion Starter #1
My 929 throttle body assemblies should be here tomorrow and I should have them road ready by the end of the week. The track opens on the 6th and I want to compare them to my edlebrock performer x intake.

I know alpha-n is the way to go below a certain rpm but how do I know when I cross over to map reading? Also how do I know what mbar to set the tps percentages to for low rpm stuff? Im hoping to get them fairly dialed in next week so I don't spend all day at the track not getting anything done with them.

Any help, info, or insight on tuning this would be much appreciated!
 

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Discussion Starter #3
I have the 600s but they are too close and you need to space them to have them line up better. So I bought the 929s and they come with the factory air box which I plan on running because I want a air filter if I decide to leave them on.
 

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Discussion Starter #9
Can you explain the alpha-n...you know, I get it, just for everyone else...


(secretly I don't know lol)
Its tuning by tps only it doesnt use the map sensor. In ectune it looks like you can set the a certain tps voltage to equal a certain map sensor voltage.

What tuning software are you using?
Ectune with a ostrich and hulog

use full alpha-n. don't waste time tuning with map.

if your tuner is good enough alpha-n will drive like stock on the street.
Well I would like to tune it myself to keep the cost down on this project just in case I dont find them to be better than a intake manifold.

A well setup Edelbrock will make more power than ITBs.
My findings. Feel free to disagree.
Im not expecting to see a huge change at wot actually but mpgs and drivability Im expecting to be worse.
 

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Discussion Starter #10
Got some beginning pics with the 600 itbs and you can see how the outer two throttle bodies are way too far in.



If you split the itb assembly into two pieces they actually line up really well. Just have to modify the throttle linkage and the fast idle linkage. I also measured from the flange to the firewall and I have about 13 inches to work with so hopefully they will fit or I might have to angle the runners to make more room.
 

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i was just looking around in CROME ITB, it gives you the lower half of a normal fuel map so that the idle is a little bit easier to tune with the IACV, then for everything over something like 30% throttle it switches to alpha n to give you maps with throttle % instead of vacuum. I'm not sure if that is what they mean by just strictly alpha n but it seems like it would work very well, just take a lot of time to tune.

also i noticed on one of the b series throttle bodies i have around they actually use a cam style throttle to open slowly for small throttle movement then then really fast for the last part.

if you somehow use that sort of a design i could see part throttle driving being much more enjoyable and smooth.
 

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How do you hook up and use the IACV with ITBs?
you can make a small vacuum chamber that has a tube from behind each of the throttle bodies to get a signal source. then you can hook up your iacv to that with the one end from a filtered atmospheric source then the other side to the vacuum block.

from what i have found there is a bit of a trick in getting the hoses and the block the right size so that you can get a steady signal and so that it's not too big to reduce the advantage of the ITB's

i even read about one person tunning a f20c this way with ITB's only using vacuum. i think he was using megasquirt. but the same principals apply.

i havn't done it my self but idle tunning seems like it would be much easier this way and that seems to be the place that people have the most trouble with, claiming that they loose fuel efficiency.
 

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From what I've read you don't use the iacv you just plug it in. The itbs run such low vac that its unable to do anything. When I start putting this together I'll start a thread in the showcase section.

Lost Internet today. Neighbors I've been stealing it from must have moved out so I'll make a phone call in the morning. Lol

I'm thinking I will just use my current map but switch it to alpha n and save it as a new one for hopefully a good base map. I will play with the alpha settings to maybe get a better idea of how exactly it works.
 

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From what I've read you don't use the iacv you just plug it in. The itbs run such low vac that its unable to do anything. When I start putting this together I'll start a thread in the showcase section.

Lost Internet today. Neighbors I've been stealing it from must have moved out so I'll make a phone call in the morning. Lol

I'm thinking I will just use my current map but switch it to alpha n and save it as a new one for hopefully a good base map. I will play with the alpha settings to maybe get a better idea of how exactly it works.
if you aren't using the iacv there is absolutely no reason to plug it in. just disable it in the your programs features.

that sounds a little bit suspicious to me. you may want to do more reading on why someone would do that.
 

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Discussion Starter #18
I have seen one set up with the iacv hooked up and the rest with out it. There is a very good itb DIY thread on d-series and they explained it in there.

Found this to be a good read for how alpha-n works. The first reply is where the good stuf was at I didn't look much further past it.
http://www.redpepperracing.com/forums/index.php?showtopic=45504
 

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I used an IACV with my setup. No reason not to. A little bit of fab work is needed to make an adapter that outputs 2 nipples. Then one goes into the intake area which has a filter around it and the other one goes into the vac manifold.
 

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use full alpha-n. don't waste time tuning with map.

if your tuner is good enough alpha-n will drive like stock on the street.
I'll disagree, since I live in an area closer to sea-level, but with enough changes in air pressure to make a difference in AFR on a straight TPS tune.

A well setup Edelbrock will make more power than ITBs.
My findings. Feel free to disagree.
ITBs are being replaced with better manifolds in all forms of motorsports, or, there are plenums being used to harness reflected waves to supercharge the intake tracts on well tuned ITBs cars. ITBs used to be king, but, along came CFD and fast computers.
 
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