Learn me..... ITBs

oldeskewltoy wrote: do some research into helmholtz intake tuning. See what your engine wants, and then see how best you can do it

The factory intake setup on this motor had something to that effect....

Variable Resonance Intake System.

Alpha N pretty much squirts based on only TPS, RPM and coolant temp

Taiden wrote: Alpha N pretty much squirts based on only TPS, RPM and coolant temp

How does it compensate for load differences in different gears?

Or am i stuck in turbo-land?

92CelicaHalfTrac wrote:

Taiden wrote: Alpha N pretty much squirts based on only TPS, RPM and coolant temp

How does it compensate for load differences in different gears? Or am i stuck in turbo-land?

short answer: turbo land

But you're right, it's not very forgiving to changes. Speed density is, IMO, the most forgiving. But it seems to be the hardest to run with ITBs. Mass air meters are big dumb oafs that work. (IMO)

92CelicaHalfTrac wrote: How does it compensate for load differences in different gears? Or am i stuck in turbo-land?

The issue with ITB's, is that for very little throttle movement, you lose pretty much all of your manifold vaccum - the computer cannot really sense "load" when there really isn't much vaccum at anything other than a closed throttle.

The nice thing, is ~because~ of the gratuitous throttle size, load is really more directly related to throttle %, rather than vacuum. Therefore, having the computer read the TPS and "interpret" this as a MAP reading (MegaSquirt has a table for this) works very well.

I tried for a year and a half to get speed-density working with my ITB's. I was stubborn and figured I could do it. I was wrong. Alpha-N works really really well.

BUT, you need a damn good TPS signal. My GSXR TPS was a piece of epileptic poo and I could not filter the wretched signal. I adapted a GM sensor to the ITBs and all was well in my world.

Taiden wrote: But you're right, it's not very forgiving to changes. Speed density is, IMO, the most forgiving. But it seems to be the hardest to run with ITBs. Mass air meters are big dumb oafs that work. (IMO)

See, and I figured MAF was the 'better' way - since it measures actual airflow rather than calculating it based on a VE table. I've been meaning to do some reading on that for nefarious MSII purposes.

I'll bet that v6 sounds alright with those ITB's. ;)

SkinnyG wrote:

92CelicaHalfTrac wrote: How does it compensate for load differences in different gears? Or am i stuck in turbo-land?

The issue with ITB's, is that for very little throttle movement, you lose pretty much all of your manifold vaccum - the computer cannot really sense "load" when there really isn't much vaccum at anything other than a closed throttle. The nice thing, is ~because~ of the gratuitous throttle size, load is really more directly related to throttle %, rather than vacuum. Therefore, having the computer read the TPS and "interpret" this as a MAP reading (MegaSquirt has a table for this) works very well. I tried for a year and a half to get speed-density working with my ITB's. I was stubborn and figured I could do it. I was wrong. Alpha-N works really really well. BUT, you need a damn good TPS signal. My GSXR TPS was a piece of epileptic poo and I could not filter the wretched signal. I adapted a GM sensor to the ITBs and all was well in my world.

Thanks!

These are all questions i'll have to ask the PO. I know he had it running quite well, and i believe the TPS is included.

I appreciate the info on Alpha-N, i'll do some reading.

njansenv wrote:

Taiden wrote: But you're right, it's not very forgiving to changes. Speed density is, IMO, the most forgiving. But it seems to be the hardest to run with ITBs. Mass air meters are big dumb oafs that work. (IMO)

See, and I figured MAF was the 'better' way - since it measures actual airflow rather than calculating it based on a VE table. I've been meaning to do some reading on that for nefarious MSII purposes. I'll bet that v6 sounds alright with those ITB's. ;)

There's a link to a youtube vid on the first page.

It sounds.... unholy.

92CelicaHalfTrac wrote: There's a link to a youtube vid on the first page. It sounds.... unholy.

Where's the link? I can't find it. I wanna hears thems!

I was lying apparently.

http://www.youtube.com/watch?v=toughTZ9PIw

There you go.

Alright, i found some more out about it....

1) It comes with the Gixxer TPS. Unfortunately, it mounted on the OTHER end of the assembly from the throttle cable, which made getting a good tune on there via Alpha-N near impossible. By the time the TPS saw a signal, the throttles closest to the cable end had already blipped a little bit. I'm sure part of this is also because it's a Gixxer TPS like was mentioned before.

2) PO does say that the setup is VERY modular and it should be easy to move the TPS to the other end where the cable is.

3) The setup has huge vacuum runners and it was found to be way easier to tune via MAP using those runners.

I think i need to do more reading, see what my buddy says in terms of which he would be more comfortable with in terms of tuning, and probably give DIYAutotune a call and see what they recommend for all things.

Sounds like it's time to support a site advertiser!!!

This might help:

http://77e21.info/megasquirt.htm

turboswede wrote: This might help: http://77e21.info/megasquirt.htm

I need to learn some terms better....

But i see that there's SD, Alpha-N, "blended," and apparently Megasquirt has a dedicated "ITB" mode now...

I believe my choice has been made for Megasquirt. Thanks! Awesome link! Still much reading to do in there.

I would like to go ITBs on my e30. But mostly for the novelty.

Taiden wrote: I would like to go ITBs on my e30. But mostly for the novelty.

I gotta admit that some of it is novelty...

But this was actually cheaper than the alternative IM i was going to have made, and may actually yield even more power. (The manifold i was going to have made was previously dyno proven at a 27whp peak gain on an otherwise stock motor, let alone mine.)

The stock manifold gives a nice fat powerband which is great for a 2800-3000lb car. Not something i care so much about in a 2100lb car with even tighter gearing. I'm anticipating at least the same gain with the ITB setup, and will probably play nicer when my other set of solid lifter heads w/ custom grind cams get slapped on and i push this sucker to 9000rpms+.

These motors are so cool.

Man, that KL just looks right in that miata.