Dat sound - ITBs

[Genomaxter]

Drive a broken in car. I have 9200miles on my car and the pull from 3k on is much better than new.

[Turdinator]

Hypothetically, if you overcame the issues drive by wire presents, could you run a manifold over the ITBs and ducting utilising the factory MAF? If this were doable you could still use something like Ecutek to manage the motor as it seems to be the only thing that will run the D4S as its meant to be...

[Coheed]

The simplest tuning solution for the Direct injection is easy. Just don't use them. Port injection on ITB works just fine with proper tuning. Hope you got good gas where you're at though. The car won't like any less than 93 without the DI, if it even works on 93 that is. I think you could do it.

[serialk11r]

Originally Posted by Torquemaster

Next advantage: With ITBs you can fit race cams with a duration of more than 300°/1mm lift without any idling issues or part throttle hopping.

Uh, I think you're making it sound too easy. What's happening is that between intake events the runner is filling with quite a bit of air, and you end up blowing air (and exhaust) back and forth across the valve. This happens with all engines but the throttle being so close to the intake port means the pressure fluctuations are bigger. This makes it harder to get it to idle consistently, and have low speed low load driveability. All engines have phasable cams anyways, you just crank it to maximum retarded position at idle on a normal engine. With ITBs that would increase your idle troubles.

Not to mention needing speed density tuning is not a good thing at all.

Originally Posted by Turdinator

Hypothetically, if you overcame the issues drive by wire presents, could you run a manifold over the ITBs and ducting utilising the factory MAF? If this were doable you could still use something like Ecutek to manage the motor as it seems to be the only thing that will run the D4S as its meant to be...

I don't think drive by wire causes any issues in itself when using it with ITBs, it's that ITBs pose a low speed driveability problem by nature. In fact having an ECU be able to control the throttle bodies might even be better since they would at least be able to adjust throttle position in conjuction with valve timing and not have to react to a throttle input. You can tell the ECU to modulate the ITBs and eliminate some of the lag that arghx7 mentioned is programmed in to account for the plenum filling time, but that doesn't make it any easier.

For fun, a few possible ideas that I think could possibly work without too much trouble and make the driveability better: One solution could be an upstream common throttle body that's used only for low speed, and open up the ITBs a bit. Another is to try to get the individual throttle bodies to seal nearly completely and control idle with vacuum lines going to each intake tract (which you need anyways for "manifold" pressure sensor I think, along with the usual obvious vacuum accessories). Basically move the idle air controller to where the pressure sensor goes and make sure the throttle bodies don't leak much air.

But really now, the speed of sound is over 300m/s, you only shave a couple thousands of a second off the actual theoretical best possible response time. I think dialing out the typical built in throttle input dulling/lag should yield stellar throttle response with much less hassle. Ideally of course you have output control right at the intake valve a la Valvematic/Valvetronic with zero lag but those particular systems are not suited for high rpm.

[Torquemaster]

Originally Posted by serialk11r

Uh, I think you're making it sound too easy. What's happening is that between intake events the runner is filling with quite a bit of air, and you end up blowing air (and exhaust) back and forth across the valve. This happens with all engines but the throttle being so close to the intake port means the pressure fluctuations are bigger. This makes it harder to get it to idle consistently, and have low speed low load driveability. All engines have phasable cams anyways, you just crank it to maximum retarded position at idle on a normal engine. With ITBs that would increase your idle troubles.

@serialk11r
with respect,please don`t misunderstand me, but what you state is a completly abstract consideration. Poor idle on plenum engines with big overlapping valve lifts is affected by re-sucking exhaust gas into the inlet tract, this causes too lean mixture for combustion. This is not a solid condition and varies from one ign. to the next.With ITBs this appearence is almost completly fixed.I don`t assume this, I know it by doing such engines for more than 20 years. We startet in 1986 with the first Weber Alpha injection systems with ITBs, a friend of me was the head of Sorg Motorsport in Germany, most famous VW Tuner in the south,he died unfourtunatly 3 years ago.
I was developing the first reliable Opel Omega racing engine in 1990, the first engine has had an overlapping lift of 6.3 mm, the engine had similar to ITBs a flat plate throttle and ran smooth idling with 900 rpms if I would so (dangerous in terms of cam wear of course).

But not just me, in Germany (as well west Europe) are ITBs state of the art if you have not too much trouble with emission tests, a race rule which forbids ITBs or - of course - charged engine which doesn`t need them. In Germany theres actually a race series with 2 L-engines where ITBs are forbidden, max. 8500 rpm, cams are widly free. The inlet tract with 4 runners, no ITBs, one big plenum with a single- I guess - 65mm throttle. This engines are idling as a bag of coconuts, terrible to look at. You have to enrich the CO up to 6% to get them run. Power is about 260 hp. In 1998 I did the Opel STW-engines for Roland Asch,he`s a well know german driver, with 4 barrels ( similar to ITBs) 312 bhp@8400, N/A of course. Idling smooth as a sewing-machine.

Thats why I love this technologies. The BMW M3 engines are featured as well with ITBs, BMW knows whats to do for a successfully racefeeling sportscar with an amazing throttle response. As well Porsche makes currently the most powerful N/A engine with ITBs: the GT 3 RS makes 500bhp out of 4 Litres for street use, f***ing hell But I admit: it was alot developping expense to make ITBs customer-suitable with long term working emission control, the requirements in our half-light surroundings might be much less critical.

Guys, we have to solve the OBD-problem in conjunction with stand-alone ECU + ITBs, don`t we have the experts with good ideas? I admit I´m no electronic junkie at all, just doing mechanics...

Cheers

Udo

[serialk11r]

@Torquemaster

Okay so the thing is the idle is better because the large pressure changes make it so that the pressure is higher during overlap phase and doesn't draw as much exhaust into the intake. The problem is that the way ITBs "fix" this problem is by virtue of incurring greater pumping losses.

To really fix the issue with idle on big cams, you should have a good cam phasing system with very wide range of adjustment. The FA20 I believe has a rather big range of adjustment and has quite a bit of room to "spare" if I'm not mistaken. In fully retarded position, the intake valve can open something like 10 degrees ATDC. Thus, it's reasonable to conclude that a bigger intake cam with up to 10 degrees overlap increase or whatever would be something the engine can handle well given that the valves aren't hitting the piston yet.

[wparsons]

Originally Posted by Torquemaster

Thats why I love this technologies. The BMW M3 engines are featured as well with ITBs, BMW knows whats to do for a successfully racefeeling sportscar with an amazing throttle response. As well Porsche makes currently the most powerful N/A engine with ITBs: the GT 3 RS makes 500bhp out of 4 Litres for street use, f***ing hell

If you really want the most efficient system, look at the BMW Valvetronic system, WAY more efficient than any TB, single or individual.

http://en.wikipedia.org/wiki/Valvetronic

No pumping losses, just smooth and instant response. Double VANOS + Valvetronic means you can put in a bigger "cam" simply by tuning the software running the systems since timing, lift and duration are all infinitely variable.

[ame="http://www.youtube.com/watch?v=rEELtXVTymU"]BMW Valvetronic - YouTube[/ame]

Not really possible to add as an after thought, but still an awesome system!

[nashsnazzy]

Don't many BMWs have ITB from the factory? I read about how finicky aftermarket ITBs are so I'm wondering why they are and the BMW ITBs aren't. I'm an ITB noob so please be kind with your response.

[serialk11r]

Originally Posted by wparsons

If you really want the most efficient system, look at the BMW Valvetronic system, WAY more efficient than any TB, single or individual.

Not really possible to add as an after thought, but still an awesome system!

Well, there is one drawback to Valvetronic...ever wonder why all BMWs have it except the ITBed M series cars? Ever noticed how most of these bimmer engines have a pretty low rev limit? The extra rocker becomes a high rpm liability, and the increase in friction is definitely a problem. I heard that VQ37VHRs have oil overheating issues because the valvetrain friction is so high, but I might be misinformed.

Ideally we'd want full control over duration and lift, but such a mechanism is guaranteed to be complicated. Fully electronic or hydraulic actuation is a possibility but at that point you start consuming incredible amounts of power just running the valves.

Luckily, there are "external" (TGV, closing 1 intake port, multiple injectors per cylinder, etc.) ways of dealing with the lift compromise, so there is a nearly ideal solution, which is to have a cam with infinitely many profiles on it that slides along. Ferrari has this but I think they use it to bias lift and have moderate duration control, which is great if you're only operating at full power. The "well rounded" approach is this:
http://en.wikipedia.org/wiki/Helical_camshaft

The "helical" nature of that particular design means you can't really do much lift adjustment but you have a huge range of duration adjustment. If you just ditch the helical setup and grind one fat cam lobe that slides around it should be possible to accomplish the same thing.

Now the obvious drawback is that it costs far more to machine a cam lobe like that, and if the camshaft wears significantly it could completely throw off everything.

Originally Posted by nashsnazzy

Don't many BMWs have ITB from the factory? I read about how finicky aftermarket ITBs are so I'm wondering why they are and the BMW ITBs aren't. I'm an ITB noob so please be kind with your response.

This is pretty obvious, would you buy a car from the factory that has driveability problems, especially for 60000 dollars? I think you know the answer. They spend $$$$$$ to get it working right, that's how.

[soros151]

Oh HOW MUCH DO I MISS THEM!!! That whistling sound.

[slava]

Reviving this thread. Skimmed through the last 3 pages. Has anyone successfully made this happen yet?

[SirBrass]

So, ITB means Individual Throttle Body?

From what folks are saying, there's a performance increase with these that would rival a supercharged or turbo'd engine without them. How so? What does one throttle body per cylinder do better that a single throttle body for all 4 cylinders does not do?

[civicdrivr]

Originally Posted by SirBrass

So, ITB means Individual Throttle Body?

From what folks are saying, there's a performance increase with these that would rival a supercharged or turbo'd engine without them. How so? What does one throttle body per cylinder do better that a single throttle body for all 4 cylinders does not do?

I think that is a bit of a bold statement.

You get two things with ITBs - direct airflow and response. They will definitely gain power, but they are a pain to tune and you really won't get the most out of them unless you do head work + cams. I've seen K20s put down 300whp with ITBs + head work + cams, and the sound is amazing.

[SirBrass]

What do you mean by "direct airflow response"?