Toyotec presents...the effect of ITBs on a bone stock 16V 29/11/11

Introduction



Discussion along these lines are nothing new on Club GTI, and have been taking place for years:
In the past, people have grown an acceptance that noise and adverse fuel economy is all that can be expected from fitting ITBs to a standard 16v. As a result, the idea was commonly rejected.
Today many fit bike itbs or even more expensive components to the 16v engine with varying success.


The project and background

Recently I have been steering a project to adapt a set of Toyota 42mm throttle bodies from a 4AGE 20v "silver top" engine, as found in JDM Corolla based models from AE101 to AE111 i.e Ceres, Mario, Corolla and Levin, both AT and MT. The throttle build thread will be added soon in a separate thread, but the testing here demonstrates what happens when 42mm ITBs are fitted on a 2.0 ABF 16v.
What this report does is explode a myth.
The background is Ben S's Mk2 which has been in various stages of published development, most recently here with a modified inlet plenum. Ben kindly allowed his car to be used as a test mule for this ITB exercise, and with this car, we already had a lot of testing data for comparisons to be made. Being the same engine, this increases the value of the R&D exercise immeasurably.

Firstly, the definition of 'bone stock' in these results involves standard hardware i.e base engine head and block. The vehicle's engine is controlled by a Megasquirt ECU, used universally to control the engine to optimum operating conditions, whether with a standard plenum, a modified plenum or ITBs.


Cost and special test conditions

This exercise cost ~ 300 in parts, including cooling components, albeit fitted to a vehicle already running Megasquirt. If this sounds like interesting stuff, read on

Please note in order to keep test consistency, these additional controls were implemented.

• The tyre size was 195 45 R15.
• The vehicle was run with 1/4 tank of fuel.
• The location of test and direction was always the same.
• The driver was the same
• The vehicle always had the same two occupants.
• The calibration was optimised to LBT and MBT for each test subject.
• Tests are run in second gear as in most NASP cars this is a good compromise between wheel slip and rolling/aero drag

Validating the drive and test results

Track day and general driving impressions with the Toyotecwerke throttles

The car was tested at the season closing trackday on >>Nov 5<<

Ben later reported that the car:

• Had no reduction in fuel economy i.e up to ~40mpg during cruising and general driving.
• On a full MK2 Golf 45 litre tank, some 10 miles from the the track venue, the car was able to run approximately 90 miles on the track at mostly full loads, then drove some 95 miles back to Essex followed by G meter tests where it had a 1/4 tank remaining.
• The cold start calibration was very robust during crank, run up, warm up and pull away.
• Transient response through throttle angles/engine speeds was very progressive, helped by a throttle cam designed for a family car.
• Low to part load driveablity as good as the plenum/speed density calibration.
• Brake servo vaccum not affected using runner 1 and 4.

He also said, "No need for a radio with those trumpets in front!"


Comparison Gs OE intake vs ITBs

Here is the result of a G-meter test, comparing base ABF w/MS1v3 on a standard plenum and the Toyotecwerke ITBs:



As posted elsewhere on Club GTI, the G-meter plot represents the actual clutch torque from a= F/m where:

F= Force at the wheels derived from clutch torque, after frictional losses.

m= mass or vehicle inertia weight.

a = axial acceleration in Gs.

The G-meter result shows a clear increase in acceleration (more wheel torque) from fitting the ITBs. The vehicle has seen no loss of low down torque and has gained significantly from 4,000 rpm. As power is a function of torque, should the vehicle have been rolling roaded, it would show an increase in power.


Comparing the throttle system vs the Ben S optmised Big plenum/ short runners vs OEM

This graph shows the difference between a standard inlet manifold, Ben's modified manifold and the ITBs. Clearly improvments have already been made with the inlet manifold modifications:



In spite of the improvements that were achieved with the optimised "big plenum/short runner" system, the ITBs still demonstrate an advantage at higher engine speeds.

Conclusions and thoughts

These ITBs, show an obvious benefit at higher engine speed ranges vs a std intake manifold. Where these ITBs may differ from others is in the tuned length, position of throttle flaps and injector position (OEM in this case). However, I would see no reason for off the shelf ITBs not to deliver a similar pattern of improvements when installed and properly calibrated.

My subjective comments and thoughts when the car was driven after each manifold change was.

• OE manifold - car felt "flat". Induction noise makes engine feel as if it lacks character. Still a quick car though.
• Big PL/SR - car felt much more urgent and quite responsive from part loads to WOT. Makes a pleasing intake noise but runs out of puff at around 7200 rpm.
• ITBs - urgent everywhere and really gets going around 5000 rpm and reving to 7500 rpm. A bit boomy at 6000 rpm.
• Intake note changes from harking to brraaappp! @ 1000-3000 rpm to melody from 3500-5000 rpm, then all 4 throttle get very raspy at 5000-6000 rpm before it gets very vocal and boomy to the new 7500 rpm cut out.
• Calibration philosophy for alpha-N different to speed density

This is an interim report on a project. Stay tuned. All being well this is just the start

Many thanks to all who took part in making this happen.


Regards
Toyotecwerke.




Please note some what you see here may involve specialist skills and I cannot accept any responsibility if you underestimate what was done here and damage yourself, your car or others in a similar attempt. This is for information purposes only and use at your own risk.

 

Nice reading & info...

 

Great work, i have been plugging ITB's for years. Well done.

 

Now where did I leave my spanners....

Good work Ed. I really should sort some out for myself too. I could do with some extra Go's topend.

Gurds

 

Very interesting stuff, Eddie, and approached with your usual scientific rigour! Is the wobbly shape of the torque plot an inevitable feature of using a G-meter - road bumps and varying grip maybe?

How did the Toyota ITBs fit to the VW head as standard - did you have to do much re-spacing, or are they about right as standard?

How does the driver experience stand up at light throttle driving - e.g. around town?

 

Cheers happy that you found it useful.

You have indeed and now you have further justification.

Get those spanners out...its cold but you know you want to!

Yes the plot oscillations are attibuted to suspension activity and road surface uneveness. The software in the meter and in the PC GUI does attempt to filter/dampen these noises to display the Gs you see here.

I will demonstrate how the throttles were integrated into the system you see here, in a seperate topic.

I may have been editing the thread when you wrote this. I put that experience under the Ben's feedback after the trackday as no different from a plenum/speed density calibration.

 

Nice stuff. Good to see proper data in regard to the rumours. I guess there will be alot of searching now for ITB's

 

This is a great project. I can confirm the car remained very easy to drive at low speeds. The transformation in the cars character and performance makes it a very worthwhile modification in mu opinion.

 

Nice results Eddie, up to the dyno...

 

Thanks for the answers - really looking forward to see how this develops.

 

Are those run without filters? is there going to be a filter adapted to fit?

 

The system was on Ben S' car only for a short time so yes w/o filter during the above exercise.
However this is the filter that will be fitted to it when it finds its new home soon

 

Nice Thread Eddy

what is the measurement from the valve to the butterfly (300mm) ? and the overall length of the inlet to the valve ?

ITB's are the future

 

Erstwhile-believed myth => bin. And I believed it.

The value of properly-evidenced, documented research. Long may it continue.

Doffs cap

 

What I have never understood is why people would ever think ITB's would have a negative effect. They offer the cleanest, smoothest path for the air to flow, therefore offering the greatest efficiency at higher revs, all revs! Simple straight inlet track over the 90 deg bends in a plenum = ITB Win.

I'm sure there have been many bodged home brews around that have been crap but that is not a fair assessment of ITB's. there are plenty of good of the shelf stuff that is bolt on and enjoy. To all the haters in the years you have been missing out!

 

I will give out more details on this in an upcoming thread. They have been design with a purpose

Many thanks.

Of course and what you are also highlighting is that it takes more than just a "good home brew" (or off the shelf) component to realise a result in certain direction.

 

Just an observation, but from my understanding of the original 'anon' quote it was made in reference to putting ITBs on a completely standard car including standard ECU, we all know that there are gains to be had by fitting a SEM and obtimising this for the induction system fitted, I find the title a little misleading for that reason.

 

Because most of the setups on standard engines are too short on the runner length. Resulting in reduced torque vs. standard setup, making ITBs look bad.

examples:





even this one by mate of KentGTI on here:





^ MS ABF with plenum easily makes over 220Nm, Smudge & Toyo throttles also make way over 220Nm and hold on to the torque long enough to produce over 180bhp. All these engines have ABF cams. Example shown above makes 180bhp but has a reduction in torque in low to mid rpm.

 

The engine is std and was never opened. It was made clear that the SEM allowed all the control conditions to be consistant between manifold steps i.e between speed density mode and alpha-N.
This allowed the improvements as demonstrated numerically, to be short listed toward the test subjects and hence the title.
I would not expect a OEM Digifant 3.X ECU (speed density) to effectively run these throttles without a serious tear up of the calibration ethos.

 

Eddie that is exactly the point I am making......original comments made about benefit of fitting ITBs to a std 16v, I beleive, were based on said vehicle being still fitted with OEM Digi ECU and therefore no real benefit for the money spent!

I understand your approach and agree that benefits can be exploited when fitted in conjunction with SEM but feel that your quoting of the 'anon' post is a little biased and misleading. I am just stating my opinion