Crazy KA24e ITB Turbo idea.....

[hoogin89]

So one of the main problems with ITB's is that you mess up the MAF sensor because you cant have four individual MAFS.  However in a turbo application, you put the MAF at the inlet of the turbo.  So I guess does anyone think it would be possible to run a turbo with a MAF to and intercooler, then have the intercooler quad pipe exit into ITB's?  I know it could be done with a plenum on top of the ITB's but that kind of defeats the purpose of ITB's, however this would be a turbo application so as long as the plenum stayed pressurized would the motor benefit from ITB's?  Obviously a new ECU map would have to be made, but does this seem like a somewhat logical idea or utter stupidity?

[Basic]

not an expert on this, but its my understanding that the benefits of ITBs are an increased throttle response and an improvement in airflow efficiency. Both of these could be achieved with leaving the plenum in place before the ITB. Basically the plenum would also be under pressure (be it boost or atmo). Honestly, this isn't too crazy of an idea - the RB26DETT uses ITB now..

[iceageg]

Yes, your thinking is sound and on paper it can have distinct flow advantages.  The basic idea has been used in aviation for a while and boosted by my company.  I posted some details about it here http://club-s12.org/retro4/index.php?topic=33597.msg349240#msg349240 a few years back.  There is no MAF in this application but there is boost and a single throttle body prior to an equal length intake plenum, simulating an independent throttle body setup with fewer parts.  There are some parts of this design that would not be optimal for a car just because of how/where the engine is operated vs. an airplane but it is very close to your idea already in use and verified as beneficial.  In this application I can tell you that yes, the improvement over a traditional intake setup on the same engine is massive.

That said, there are a few things go consider going this route.  The first is custom fab.  You won't find many (if any) parts available for this, so be prepared to cut/weld/grind/source all sorts of things more than once.  Some consider this the best part, others get discouraged.  Would be a cool looking setup though!  Also, since you will be taking up room on the intake side with more throttle bodies and ducting so potential mounting locations are limited as well.  Another thing, one of the things that make ITB's work as well as they do normally aspirated is tuning the length of the intake tubes to match your desired RPM range.  With boosted applications this is not as critical but still a factor.  Because of all the ducting it can be more difficult to adjust the length on a boosted application and likely not worth the effort unless you have unlimited time and funds for dyno time and extra parts.  Finally, placing all that duct work, intercooler and a turbo in front of the ITB's will eliminate much of the "throttle response" benefit unless you are already spooled up, so don't be surprised if you don't get much instant gratification driving in town or on the freeway.

[Basic]

on a quick search I ran across a non-technical article dicussing ITB over at import tuner - pretty interesting stuff  - http://www.importtuner.com/features/0801_impp_itb_setup/viewall.html

I especially found the fuel injector outside the ITB interesting, using the turbulence around the throttle plate to mix the fuel better, and the additional distance to allow the fuel to expand more before entering the chamber.

[iceageg]

Good article.  For forced induction I don't think horns will benefit you at all but it does offer a lot of flexibility for injector placement with all the extra ducting.  Just remember how the article starts . . . be prepared for failure, followed by retry!  New things don't usually go right the first time and you invariably end up saying, "I wish I had done XXXX a little more YYYY" even if when you do get it right the first time.  If you stick with until it works (or you figure out you were wrong all along) you may find yourself an authority on something without intending to be.