http://tdi-plc.com/blog/category/japan/lexus-is200/is200-supercharged-stage-2/

We are mighty proud that our client chose us to deliver his dream of owning the worlds most powerful supercharged Lexus is200 using the original 1G-FE engine. There are more powerful cars around using a different engine or using a turbocharger, but this car really is something very special.

Although we have more experience with Lexus cars than any other company in the UK, when commissioned we knew that we were charting completely new and unexplored territory and so this project was going to be a challenge.

The engine and engine control functions had already been previously uprated as can be seen on the previous blog, so all we had to do was to adapt the Rotrex – Antonov supercharger to the Lexus iS200 and deal with any issues as they arise.

The Rotrex supercharger is a very efficient and compact centrifugal supercharger. The Antonov conversion introduces a 2 speed internal transmission to increase the boost pressure at low engine speeds.

Although Rotrex offer larger superchargers, Antonov had developed their technology only on Rotrex superchargers rated up to 400hp.

Our design brief was to get as close to 400hp with compromising the “Lexusness” of the car, which means that could not produce a car with too much intake or exhaust noise, and we had to retain the smoothness for which Lexus is renowned.

Here are some pictures of the Rotrex – Antonov supercharger installation:

Rotrex supercharger with the compressor housing removed.

Rotrex compressor housing

Rotrex – Antonov supercharger retention cradle manufactured by us.

Another part of the cradle.

Here’s the Rotrex – Antonov supercharger during mock up.

The Rotrex – Antonov supercharger runs on special traction fluid in it’s own remote reservoir.

Here are the mounting brackets after final treatment and installation:

Here’s the final completed installation:

Here’s a short video of supercharged engine with disconnected pressure pipes:

http://www.youtube.com/watch?v=P5jHgLbVUbM

We were very pleased with the final outcome but went onto deal with some normal development and teething issues which are to be expected when breaching new frontiers by creating something that has never been done before.

The first thing we found was that because we had to retain the standard TTE air filter box to minimise the induction noise (which was totally unacceptable with an open induction kit), there was an enormous depression inside the air box (caused by it’s own restriction) which was trying to suck the K&N filter into the supercharger!

This issue was relatively easy to resolve by manufacturing a filter retention mechanism inside the air box.

The next issue became apparent at a Lexus Owners Club day meeting here at Torque Developments. After several hard runs loaded with passengers, the car developed a misfire at full throttle.

The cause of this issue was located after undertaking an exhaust back pressure test on our Rototest chassis dyno. We found that we had 2.5 bar (absolute) of back pressure in the exhaust system!!

This was then quickly tracked down to the catalytic converter which had melted and blocked the exhaust system. Although it was a hi flow racing cat, it was too small for this application, and the standard front pipes were still being used which were too restrictive and generating excessive heat.

Here’s the melted cat internals

This issue was resolved by installing a larger catalytic converter and hi flow down pipes.

The next issue that came to light during daily use of the car was a failure of the standard crankshaft pulley which sheared. Subsequent dyno testing showed that the parasitic losses of the supercharger were significantly higher than we were led to believe, so in hind site the failure of the standard pulley was to be expected.

This issue was resolved by manufacturing a new crankshaft pulley

This is the extent of our development of the Rotrex – Antonov supercharged Lexus iS200 to date.

There was some contention with some people in the UK Lexus Owners Club over our Clients requirement for discretion on the power figure. Of course we intend to honour our clients wishes on this matter but i don’t think he will mind if we reveal that it will produce close to the limitations of the supercharger when the restrictions that provide it’s “Lexusness” are removed.

All in all this is a fantastic car, and we would like to thank our client for choosing us help build it.

The weakest link is the fragility of the connect rods so these must be replaced as a matter of priority.

We use forged steel connecting rods with high tensile bolts.

These can be viewed and purchased at

www.tdi-plc.com/catalog/product_info.php?cPath=107_197_214_384_389&products_id=4103

These are 4 of the 6 forged steel uprated connecting rods for Lexus is200

We also install lower compression forged aluminium racing pistons. It is important to realise that there are significant variations in piston design and qualities, even from the same manufacture. We always specificy the very best materials which have a low expansion rate. This means that we can use a tighter bore clearance which provides quieter operation and low oil consumption. Also of high significance is our design piston crown. When compared to inferior designs you can see that we have retained the squish band to maintain maximum combustion efficiency.

Here’s a picture of a piston the we use.

The forged alloy pistons for Lexus iS200 can be purchased at www.tdi-plc.com/catalog/index.php?cPath=107_197_214_384_389

Here’s a couple of pictures of the engine during the course of the rebuild

Heres the stage 2 supercharger pulley kit installed

This car has automatic transmission so you can see that getting the Katana intercooler, TDI oil cooler and TDI transmission cooler requires a fair amount of work as there isn’t much room in front!

Here’s the Katana high performance exhaust manifold installed

Here’s the finished article

We use 550cc fuel injectors with an HKS FCON V Pro engine control unit which is one of the worlds finest ECU’s, of which we are an authorised Power Writer and have a considerable amount of experience.

Here is a picture of the HKS FCON V Pro.

Unfortunately HKS do not make a pre-manufactured wiring harness for the Lexus is200 so have to custom wire each car.

The way this is done on a supercharged car is to increase the speed of the supercharger by changing it’s drive ratio.

The standard TTE supercharger system normally produces 1.35bar of boost pressure (absolute). Our stage 1 boost upgrade pulley kit produces 1.5 bar (absolute), and our stage 2 boost upgrade kit produces 1.7 bar (absolute).

Here is a picture of the stage 1 and stage 2 pulleys for comparison purposes

Here’s a picture of our stage 2 boost upgrade pulley kit (including belt)

When air is compressed (such as by a supercharger or turbocharger) it’s temperature increases (see BoylesLaw) and loses density thereby reducing the amount of oxygen available to produce power, so we can see that reducing the air temperature at the back of the intake valve is crucial for increasing engine performance.

This is why intercoolers are used in an attempt to reduce and control intake temperatures. Unfortunately the presence of an intercooler also creates a restriction to airflow which in turn reduces power so we therefore have a bit of a paradox which is generally dealt with by compromising the airflow efficiency in an effort to keep the temperatures down.

The two critical design features of an an intercooler are it’s thermal efficiency (how good it is at reducing temperatures) and it’s air flow efficiency (how good it is at transferring air with minimal internal losses).

Having very good airflow testing facilities in-house, we were able to test all of the branded intercoolers on the market and found that they varied dramatically in terms of air flow efficiency so we decided to think about how we could improve this without reducing the size of the intercooler core.

Traditionally, a larger core gives a cooler charge but more resistance to flow, so we designed an aerodynamic and plate for the core which significantly increases the air flow through the core.

We also wanted to increase the volume of intercooler core to maximise the cooling capacity so we designed a intercooler which is around 250% larger than standard. We paid particular attention to the quality so we ensured that the end tanks were properly cast and aerodynamic shaped too. We increased the size of connector spigots from 50mm to 60mm so that the Katana intercooler can be used on very high power applications. We also considered the packaging to ensure that the intercooler could be installed without cutting the body work and with minimal fuss.

The end result was an increase from the standard TTE intercooler of 123CFM to the uprated Katana intercooler of 161CFM which is an increase of 30% !!!

On the chassis dyno we found that with no other modifications, changes or tuning, we saw an increase of 0.1 bar of boost pressure (due to the aerodynamic end plates) and a substantial increase in torque throughout the power band (see graph below).

We are very pleased with the results of an additional 20 lb-ft at the hubs, and the Katana high performance uprated intercooler for the supercharged Lexus iS200 can now be bought at www.tdi-plc.com/catalog/product_info.php?cPath=107_197_214_384_392&products_id=4117

Here’s a picture of the intercooler in place

Here is the performance certificate without any tuning or adjustments being made. Very impressive!

because of the science and technology deployed in the Katana intercooler, we are confident that it is currently the best in terms of effectiveness and quality.

The standard manifold has exceptionally small primary pipe diameters (probably to assist a fast warm up of the pre-catalytic converters), and the primary pipe lengths are too short (probably due to packaging concerns) for optimum torque. The manifold also includes pre-catalytic converters which are restrictive and known to fail internally.

The first stage of our development process was to accurately measure the camshaft timing so that we could run some calculations through our modelling programme to determine the ideal theoretical primary lengths and diameters, the secondary lengths and diameters, and the collector lengths and divergence angles.

Because of the packaging issues and design of the downpipe/main cat pipe, we could not implement the ideal secondary collector length so we chose to introduce pulse tuning loops in the desired location of a secondary collector. This proved to be an acceptable solution because it provided easy interchangeability with the standard manifold and gave us a good performance increase.

Dyno testing was carried out with various combinations of pipe lengths and pulse tuning loop locations, and the final design was signed off.

The improvements in power and torque makes it ideal for all fast road applications, and for any intended race use where uprated engine internals are deployed.

Benchmark testing was carried out competitive products, and we were pleased to note that the Katana exhaust manifold outperformed the other manifolds by a very significant degree.

We were not surprised by this as the Katana manifold was (and still is) the only high performance exhaust manifold for the Lexus iS200 which has had some science applied to it’s development.

Other concerns were raised about the other manifold such as incorrect pipe dimensions, quality of manufacture, slip joints instead of being a one piece construction, the collector pipes being squashed together instead of having the correct divergence angle.

The Katana exhaust manifold can be purchased at www.tdi-plc.com/catalog/index.php?cPath=107_197_214_384_385

Here is the Katana manifold for the Lexus iS200 showing the pule tuning loop pipe

Here you can see the difference between the standard manifold and the Katana exhaust manifold for Lexus iS200.

Here you can see the difference in collector design between the Katana manifold and that of a competitor. Note the poor design of the competitor.

Here you can see the difference between the Katana and the competitors manifold. Note the sharp change in in primary pipe direction which slows gas speed.

The Katana manifold can also be heat wrapped for thermal insulation

Here’s a picture of the Katana high performance exhaust manifold installed on a Lexus is200