Question about ITB's
 

I've been trying to read up on Individual Throttle Bodies. And have been wondering, why is it that when using ITB's there is no need for an air filter? Does doing an ITB conversion hurt the engine because of not having air filters?

And since using ITB's can go with no filter, why is it that a car without it needs an air filter at all?

If this is in the wrong forum I apologize, but I figured I'd find a more knowledgeable respone than any of the other forums.

yup exactly what he said!!!!

If that's the case, then why does everyone go crazy over the idea of ITB's if in reality it hurts your engine?

Is the damage caused really that minimal compared to the gains received?

Thank you for that amazing post. A+, would read again :rolleyes:

noobs...
It doesn't hurt your engine if you use filters. You can either build a common plenum for them with a single filter, or put what they refer to as a "sock" filter over each throttlebody.

Also, I'm not sure if you've picked up on this or not in your research, but you'll need something like the Emanage with MAP functionality because you won't be able to use your current MAF unless you build a common plenum for the throttlebodies.

Yeah I've read into that about the MAP functionality, I don't fully understand it just yet but I'm still learning.

In using a common plenum though, wouldn't you lose effectiveness of the ITB's seeing as the common plenum is similar to an intake manifold with a single TB? Or is the absence of a common TB what makes the difference in power?

You wouldn't get the 100% benefit, but it would still have the same throttle response as without, I would imagine.

Also, keep in mind the powerband. Switching to ITB's, even with a common plenum, is going to shift your powerband more towards the higher RPM range.

and he means much more. but with a common plenum, i think youd find a slightly lower RPM powerband, with probly just slightly less power made. in reality, its probly better to have a common plenum if you plan to drive anywhere other than the track, you can get a better filter and lower RPM power

Kinda like this?


http://i109.photobucket.com/albums/n...3/IMG_0237.jpg

and this:

http://i109.photobucket.com/albums/n...3/IMG_0225.jpg

think about cutting off the long runners, and using the short ones - maybe with the existing butterflies? :nervous:

I've got one..... and it does bolt right on the 3.0 LIM..

Lower im from a swirl valve 00....... :wall:

On my setup im going to make fairly long runners (because of retarded aftermarket cams) but 6 small filters is muuuuuch better than a common plenum. Thats the point. Absolutely equal air in all cylinders.

Why is it that the power band shifts so high in the RPM's? Does anyone have any examples of dynos to show this shift? I'm going to search online to find some. When I find some I'll post them in this thread.

Interesting thought - would that matter with a nitrous car? Since much of the charge is sprayed, not sucked, into the cylinder???

And if you're running boost, won't the pressure force air into each cylinder more or less equally??

Which leaves a N/A car having the greatest need for equal air into each cylinder, I guess..

Appreciate the viewpoint.... What runner length would be best for 5000-6000 RPM power peak?

Not sure but theres a formula for that. Equal air in all cylinders is better no matter what induction you are running. With a common manifold some cylinders obviously get more air than others. If they are all seperated and symetrical, they will get equal air.

But to be fair, boost or nitrous is trickier to combine with ITBs. I think the RB26 comes stock with ITBs AND a common plenum.

You're right about the RB26 intake manifold layout, individual throttle boddies and a common manifold. Some people tend to convert them to a 100mm surge tank by veilside or the new trend, virtualworks intake manifold, this is a monster of an intake!!!

Can someone explain how the MAP function on the EU can be used to get rid of the MAF.

You would tie a port into each runner on the engine side of the butterfly plates and hook up a vacuum log. The pressure sensor would be there and you could tune according to that pressure. On a n/a car, the incoming air would be related to how close the pressure is to ambient and rpm.
A lot of cars use to just use a map for engine management.

Let's theorize and say I cut off the plenum of the stock IM and was able to get everything figured out as far as TB's and all the like.

Without having 6 built-in ports (like most TB's do) to tie into for the MAP sensor, what would be the best way to go about drilling the holes and creating ports for the vacuum lines without terribly effecting airflow?

Another question is should all the vacuum ports connect to a chamber and then to the MAP sensor or would it be just fine teeing all ports into one line and then directly connect to the MAP.

I'm still researching myself, but anyone who can offer insight to my endeavor, I'd greatly appreciate it.

Sorry for bringing up the old thread, just had some more questions.

Obviously you would have idle issues because of need to remove the IACV and EGR, so how would you go about removing the IACV and EGR? Would you be forced to use a stand alone engine management system? Or would there be some way to still use the oem ECU and be able to idle?

IACV and EGR are both an assist not a required part for engine operation.. removing both would throw a code.. but not allow the motor to run.. you would have cold start issues tho.. but nothing drastic.. although it wouldnt be difficuly to tap a fitting into the common plemum for the IACV.. like what they do for the VI swap.. although that depends on your IM setup..

I guess the focus would be more of something along the line of not have a common plenum.

So as far the IACV and the EGR are concerned, you're saying I could unplug both and aside from starting issues the car would idle and drive fine?

But doesn't the ECU need to IACV to idle correctly? If not, then how is idle affected with the IACV disconnected?

You can disconnect the IACV, and if you crack the butterfly in the TB it should idle just fine. EGR is completely unrelated to engine operation, it's purely an emissions device. No worry about ripping it out.

Sorry for the petty questions, I just don't completely understand everything.

How would you go about cracking the TB?

with the idle set screw? :rollsmile:

Indeed, for a more permanent setup. Just to check it out, I'd tighten up the throttle cable a little just to see how much it takes to get it to idle correctly.

Would this mean that you are then forced to have a higher idle than you normally would? I guess it wouldn't be that big of a deal, but I'm just curious.

This may be another stupid question, but are all 4 connectors that are attached to the IACV for the IACV or do some of them function for other things?

Not necessarily, no. Remember, without the IACV the only air you're getting for idle is going to be through the TB.

One of the connectors is just mounted there for the EGR temp sensor, one is the main IACV solenoid connector. I believe the other two are for PS and AC, respectively (if the AC is on or you're turning, the idle is raised to compensate for the added load on the engine).

Before running ITBs you would need to do a MAF to MAP converstion obviously. Im still waiting on those Biki boards from AU to see if they have the resoultion to do the job. I'll back up what I've heard from the pros and say the Emanage does not have the ability to run ITBs on these cars. I've had some talks with ITB makers about a converstion on a VQ30. :shiner:

You could actually still use EGR, EVAP, PCV, and even IACV to an extent. What you would need is a vacuum distrubution box mounted on the engine somewhere. Take all the ancilleries that were attached to the intake manifold and route them into the vacuum box.

Besides with ITBs you lose a common manifold but still need a good steady vacuum for the FPR and power brakes, so a vacuum box is needed anyways.

Tap the intake runners after their throttle plates to get some engine vacuum and run all 6 hoses to the common vacuum box. Then try to start the car and hope for the best. :D

I have the MAF to MAP conversion done. Actually I've found that my car seems to like the MAP better. I used to always have a hard time getting through the REV limiter in 3rd gear with the EU, I would successfully be able to do 1 every 7 or 8 time. But after switching to the MAP sensor, I go through the rev limit with ease everytime.

As far as the vacuum tank is concerned I was thinking that I would need something like that and now you have definitely affirmed that for me. So Thanks.

ITB are very expensive. Someone had did a setup on a 350z and spend close to 20k tuning. You really need a stand alone for ITB as MAF and MAP might be out of the question.

Yup they are. There are alot of problems to overcome and tuning for driveability will be a pain.

Got any links to that 350Z? Id imagine the Z setup would be much more difficult to convert cause of the drive by wire.

For most magizine shoots they take the filter off for looks. Othere wise you can make a plenum which has provisons for a filter or use small conical filters for each tb. For the real world you should always run a filter.



evo