FRS / BRZ Intake Manifold - Development Thread - FT-86SpeedFactory by Velox

[Draco-REX]

Originally Posted by bur****jp

http://www.scion.com/scionracing/wp-...reet-frs-5.jpg
Hmm. How about that.

Just because it looks good, it doesn't mean it runs good. Take another look and see that this is no street car. If it's more than a show car, it likely operates in a narrow rpm window.

Think about what it would take to tune that. How do you know how much fuel to add to the incoming air? There's no MAF, so grams/sec based measurement is out. There's no MAP, so VE calculations are out. You can only base your tune on a guess of incoming air volume based on throttle opening vs rpm. The tune would have to run essentially in some sort of bastardized open-loop where fueling would be determined by a preset table with an active adjustment based on primary O2 readings, or you'd have to have multiple tunes to handle variances in barometric pressure, ambient temp, and humidity. I'm not even sure if the stock ECU is capable of that sort of fueling model, so a stand-alone ECU might be needed.

This doesn't even take into consideration the countless dyno and track hours needed to nail down that base fueling table. A kit like this would make the Nameless header R&D look like a weekend messing around in the garage.

[gramicci101]

Just curious: how do you keep random shit from getting sucked into an ITB? I know some of them have screens in them, but those don't filter nearly as well as an actual filter does.

[HUNTERANGEL121]

Originally Posted by Draco-REX

Just because it looks good, it doesn't mean it runs good. Take another look and see that this is no street car. If it's more than a show car, it likely operates in a narrow rpm window.

Think about what it would take to tune that. How do you know how much fuel to add to the incoming air? There's no MAF, so grams/sec based measurement is out. There's no MAP, so VE calculations are out. You can only base your tune on a guess of incoming air volume based on throttle opening vs rpm. The tune would have to run essentially in some sort of bastardized open-loop where fueling would be determined by a preset table with an active adjustment based on primary O2 readings, or you'd have to have multiple tunes to handle variances in barometric pressure, ambient temp, and humidity. I'm not even sure if the stock ECU is capable of that sort of fueling model, so a stand-alone ECU might be needed.

This doesn't even take into consideration the countless dyno and track hours needed to nail down that base fueling table. A kit like this would make the Nameless header R&D look like a weekend messing around in the garage.

To tune it, do whatever tuners did on S2000s. And most Hondas.

[HUNTERANGEL121]

Originally Posted by gramicci101

Just curious: how do you keep random shit from getting sucked into an ITB? I know some of them have screens in them, but those don't filter nearly as well as an actual filter does.

Little sock filters.

[OkieSnuffBox]

Originally Posted by gramicci101

Just curious: how do you keep random shit from getting sucked into an ITB? I know some of them have screens in them, but those don't filter nearly as well as an actual filter does.

You use a foam filter.


Or have them fed by a large filtered plenum, like on many BMWs.

[himbo]

Originally Posted by gramicci101

Just curious: how do you keep random shit from getting sucked into an ITB? I know some of them have screens in them, but those don't filter nearly as well as an actual filter does.

They do make filters for itb's and production cars with itb's usually have an airbox over them.

[VerusEric]

Originally Posted by Hyper4mance2k

Looks ready to bolt together. When should I drop by so we can get this testing started?

Still waiting on bell horns .

[mad_sb]

Originally Posted by HUNTERANGEL121

To tune it, do whatever tuners did on S2000s. And most Hondas.

Or something like autronic with an auto mapping feature based on wideband feedback... or megasquirt etc etc. ITB's can work very well over a wide rpm range if designed properly, problem is most people just hack together a kit from available parts and using incorrectly sized runners.

[burdickjp]

Originally Posted by Draco-REX

Think about what it would take to tune that. How do you know how much fuel to add to the incoming air? There's no MAF, so grams/sec based measurement is out. There's no MAP, so VE calculations are out. You can only base your tune on a guess of incoming air volume based on throttle opening vs rpm. The tune would have to run essentially in some sort of bastardized open-loop where fueling would be determined by a preset table with an active adjustment based on primary O2 readings, or you'd have to have multiple tunes to handle variances in barometric pressure, ambient temp, and humidity. I'm not even sure if the stock ECU is capable of that sort of fueling model, so a stand-alone ECU might be needed.

It's not a rhetorical question for me. I've tuned ITBs on several 4A-G 20Vs. Here's the other car in my driveway:


There's nothing to say you can't implement a MAF (or two, or four) and feed the OEM ECU, but I agree that a stand-alone would likely be much more beneficial.

[Kostamojen]

The big problem with ITB's on boxers is the fact they aren't all in a straight line. Older inline motors with wire throttles, pretty easy to design an ITB setup that works. The FA motors have all the elctronic issues with the throttle PLUS having to design basically two separate pieces and all the associated bits to get it to work... Its not cheap, or easy, thats why we probably won't see one for a long time if ever.

[cjd]

In a different direction... Could a dual runner length setup be a possibility here? That seems far more useful if we're going crazy with nonexistent funds to spend squeezing every last ft/lb of torque out of this engine...

I hope the results are as nice as the parts are beautifully machined.

C

[Tim Radley]

Originally Posted by Stumpygt86

So if one was to make ITB's then they would have to have them all as individual components so the runner length would remain constant?

That is ideal for tuned lengths to match but sometimes its advantageous to run a mix of lengths. Plenty of motorcycles have run mixed lengths on inline 4's. You can tune out dips on 2 cylinders with peaks on 2 other cylinders for a straighter power curve. You still ideally need to run individual cylinder maps as front to rear will still be slightly different due to cooling and airflow due to firing orders.

[DustinS]

Originally Posted by Draco-REX

Just because it looks good, it doesn't mean it runs good. Take another look and see that this is no street car. If it's more than a show car, it likely operates in a narrow rpm window.

Think about what it would take to tune that.

For whatever it's worth, this was tuned on a Motec ECU

http://ilovegram.com/m/852481499134803805_192850366

http://ilovegram.com/m/842810462537366722_192850366

Anyway, back on topic. Can't wait to see the final results.

[mid_life_crisis]

So if ITBs are effectively only for looks on a car like this, how long until someone says "screw it" and disables the FI altogether and bolts on some downdraft webers?
Not a sound choice for so many reasons, but it would look amazing.