C20XE ITB

derost · Post by **derost** » Sat Dec 31, 2005 12:18 am

These guys in the UK make throttlebody kits for the C20XE, as well as fuel rails, flywheels, cams, programmable ecu's and some other stuff.

http://www.sbdev.co.uk

They also have a nice writeup on building up C20XE's

http://www.sbdev.co.uk/History_files/Hi ... epower.htm

Post by **PrecisionBoost** » Sat Dec 31, 2005 12:53 am

Ya... SBD has some really nice stuff.... but very expensive to get the parts to North America.

It's been a year or two since I've been on their site.... seems they have some nice pictures of the flywheels and clutches.

jonlint · Post by **jonlint** » Sat Dec 31, 2005 5:43 am

QED is another company in England that does ITBs - the put together our 230BHP XE engine - highly recommend them!

http://www.qednet.demon.co.uk/

Jonathan Linton

DArkstalker · Post by **DArkstalker** » Sat Dec 31, 2005 6:58 am

I don't understand ITB's what makes them so great.

Audacity Racing · Post by **Audacity Racing** » Sat Dec 31, 2005 7:01 am

DArkstalker wrote:I don't understand ITB's what makes them so great.

the airflow into the engine is smooth. in a standard setup there is lots of restriction and pockets and other things that aren't really efficient, but work well.

itb's send a column of air directly into the cylinder and it's quite a nice power gain over stock

DArkstalker · Post by **DArkstalker** » Sat Dec 31, 2005 7:18 am

Audacityracing wrote:
DArkstalker wrote:I don't understand ITB's what makes them so great.

the airflow into the engine is smooth. in a standard setup there is lots of restriction and pockets and other things that aren't really efficient, but work well.

itb's send a column of air directly into the cylinder and it's quite a nice power gain over stock

Is there some kind of filter or no?

Audacity Racing · Post by **Audacity Racing** » Sat Dec 31, 2005 7:19 am

nope, that's part of the racing appeal only

itb's are notriously a pain in butt to tune. if the plenum is too long or too short (by fractions of an inch) you get erratic results, but the power gains are well worth it (if going all motor)

DArkstalker · Post by **DArkstalker** » Sat Dec 31, 2005 7:22 am

Can this easily be done to the 2.2L engine or would it be a lot of money. This is something I would like to instead of turbo.

derost · Post by **derost** » Sat Dec 31, 2005 6:37 pm

ITB's also give much better throttle response, as they do not have to expend pumping power on the plenum.

Some of the problems -- as far as I am aware -- are bypassing the MAF. From what I remember, this makes idle really rough because you have to tune it for the power-band and end up rich at idle. (right?)

Audacity Racing · Post by **Audacity Racing** » Sat Dec 31, 2005 6:42 pm

derost wrote:ITB's also give much better throttle response, as they do not have to expend pumping power on the plenum.

Some of the problems -- as far as I am aware -- are bypassing the MAF. From what I remember, this makes idle really rough because you have to tune it for the power-band and end up rich at idle. (right?)

correct. to properly tune itb's your engine managememt has to be switched out to a system that defines the fuel map based on throttle position and O2 readings... which makes high end efficiency great, but down low it's not so great... read below

One of the things people don't think about when they consider engine designs is the sonics -- sound/pressure wave pulses -- in intake and exhaust systems.

Air going into, and exhaust cominng out of, an engine does not come as a steady flow -- it comes in pulses that travel through the pipes like sound waves. A curious property of sound in a tube is, it will reflect off the open end of the tube. If the wave length of the sound is equal to the length of the tube, then as the wave is reflected, it reinforces itself. This is what makes flutes, organ pipes, whistles, etc., work. It will always resonate at only one frequency, and thus the pitch of the tube will never change.

In engines, the tuned length of a tube can affect how well air or exhaust flows through it. If the wave length is just right, then an exhaust pulse that leaves the valve will be reflected back to the valve again just as it opens. And be reflected out the tube again, dragging the gas leaving the cylinder along with it. This makes the engine breath easier.

Exhaust pulses can even go down one pipe and up another, so the pulse from one cylinder can scavange exhaust from another, if their resonant lengths are right. This is why the Ford V-8 powered Indy cars of the early to mid 1960s had such convoluted, "basket of snakes" exhaust systems.

You can also tune an exhaust system for a specific rpm rage, which is why higher-revving engines (higher frequency equals shorter wave length) have shorter header pipes than low-revving ones.

The same effect works for intake trumpets. Here, air that is drawn into the engine flows until the valve shuts, thus interrupting the flow, and sending a sound/pressure pulse back up the manifold and intake trumpet. As with exhaust, if you get the wave length right, the reflected pulse will draw more air into the cylinder, or at least let air flow more easily.

And, as with a whistle or an organ pipe, this works best at only one resonant frequency. Engine designers know this, so they tune their intake manifolds and trumpets to take advantage of it. The problem is, an intake of a given length works best at only one rev range. Above or below that rev range, and its resonant frequency, you either get no boost, or an active hinderance of intake flow.

If you look at Can-Am cars of the early 1970s, you'll see they have intake trumpets of two distinctly different lengths. This was a compromise that let some of the cylinders breath well at the lower part of the rev range, and others at the higher end. The result was somewhat better breathing, and thus a better torque curve and more power.

The ideal solution is variable-length intake trumpets. That allows the resonant length of the intake track to be near optimum over a broad rev range, which gives better breathing, more and better power over a wider power band.

this is essentially the VGIS on the lanos... though variable runner ITB's are THE SEX!

jonlint · Post by **jonlint** » Sun Jan 01, 2006 3:48 am

I would not recommend ITBs for street. We have them for ultimate power, but as other say, on part throttle they are very erratic. Some ECUs allow closed-loop lambda control which would smoothen it out a bit, and our ECU allows you to set a throttle position above which it switches out of closed-loop control.

As an example of what ITBs can do, there is a German company called DBILIAS (available at http://www.regal-shop.co.uk/asps/Search ... &types=yes) that make a ITB kit for the 2.0L XE that uses the standard air filter housing, ECU and injectors and they get 25BHP increase.

mister_g · Post by **mister_g** » Fri Jan 13, 2006 7:12 pm

jonlint wrote:I would not recommend ITBs for street.

How come, it's impossible to do itb for street on c20xe, and honda has it in serial production on integra type R, 1.8 190hp?!

Dame, that's why honda is honda.... And opel will never be honda, alto c20xe is close...

derost · Post by **derost** » Sun Jan 15, 2006 9:10 pm

Not impossible. Just not recommended.

Keep in mind that the ITB's we're refering to is just the TB's and velocity stacks, and do not use a plenum or MAF.

The Honda method uses the plenum and MAF and therefore is reliable for street. It sacrifices a little of the top end efficiency of the 'naked' counterpart mentioned above, but it's way better than a single TB.

jonlint · Post by **jonlint** » Mon Jan 16, 2006 2:56 pm

mister_g wrote:
jonlint wrote:I would not recommend ITBs for street.

How come{/quote]

defrost took the words out of my mouth. I would recommend the DIBILAS system is it retains the MAF and other stuff to make the car more drivable.