Thanks F20, a friend of mine has ITBs, he gives me the same response over and over that its not worth it. as for getting air to the air horns those tie on filters are not efficient at all(according to the guys at Evolutions autosport)

people say that throttle response is improved by the amount of air sucked in, but is it work sucking in all that hot air from the engine bay along with dirt over an intake?

 

Tuning is very controversial, to say best is really an opinion, I talked to the guy who tunes for Mazda's race teams and he's run ITBs on his own cars including a Porsche and he believes the best way to tune is using TPS only. Now the guys has years of experience tuning full fledge race cars for a major manufacturer, who am I to argue?

When we tuned with an without the filters the only differnce we saw was 2hp and 2lbs of torque repeatedly. Not much of a difference, remember you can't compare every car to each other. Every car reacts differently to different kinds of tune. So making a blanket statement isn't correct. It's more of a reference from your experience. Just to clarify, I am not disputing your results, just telling you what we experienced on my car.

 

you have no idea what a relief that is to hear. I kinda figured after checkin out my engine bay today. Only vacume line I saw was for the brakes. Thank you though the lil info def helps out....

What are anyones thoughts on the spoon headgasket to raise the comp?

Any thoughts of race gas comming into play with these setups?

 

That's what support my statement. Sorry I wasn't clear on my original statement. I meant to say that MAP with TPS-blend is the best for a STREET CAR.

I've no doubt TPS-only is the best for race cars. The reason is that they don't run A/C or any unnecessary accessories or idle the car much in races. IOW, their working environment is relatively more constant compare to that for a street car. TPS doesn't "measure" air flow. It "assumes" air flow at a certain throttle opening angle. On a race car that spends most of the time at high rpm and high throttle opening angle, the assumption is accurate enough.

MAP sensor on the other hand measures vein pressure generated by the air flow thru' the throttle bodies. Yes, the vein pressure on the ITB is not as inversely proportional to air flow but at least it's more than "assumption". Yes, TPS-only tuning still takes into account intake air temp, water temp, etc. to fine-tune mixture/ignition, but there's still environmental variance that TPS-only tuning doesn't take into account. For example, when you're at WOT for some time, exhaust header is hotter than normal and helps pulling out exhaust gas from the head and eventually helps pulling in more air at the same throttle opening angle. Also, when the car picks up speed, airflow thru' the radiator can easily pressurize the engine compartment (and intake pressure) to .5psi or more. In both cases, the airflow difference is picked up by the MAP reading.

Idle speed and quality is much more important in a street car than in a race car. With TPS-only tuning, anything that causes an idle droop will have to be detected by rpm change before the ECU can do anything (that's if the ECU can detect a different between 800rpm and 750rpm). With MAP tuning, in most case an idle droop would've been seen by a moderate MAP signal change before engine speed even drops. The MAP signal change will let the ECU correct fuel mixture and more importantly ignition timing to compensate the drop.

I've tried TPS-only tuning with my ITB miata. Although plausible, it'd never give the idle quality and fuel economy of my MAP with TPS-blend tuning. My miata with +50% rwhp from stock with all kinds of N/A mods that have been "widely-claimed" to hurt emission passed emission sniffing tests every year. That's without a separate program to run thru' sniffing test. Just drive thru' with my street/race program. Furthermore, fuel mileage on that car was still much better than a stock S2000.

 

Like I said, a huge airbox with plumbing for cold air, and a single cone filter makes a big difference in ITB setup.

Throttle response is improved not because of the amount of air sucked in, but by the lack of "throttled volume" of air between the throttle bodies and the intake valves. Whether an ITB setup is worth it depends on your goal. Like I said, if it's just for ultimate N/A hp, you'll most likely be disappointed.

 

[QUOTE=GDM S2K,Dec 14 2005, 09:50 AM] I

 

[QUOTE=turbo_pwr,Dec 14 2005, 04:24 PM]Every car reacts differently to different kinds of tune.